TREATING PROSTATE CANCER WITH ANTI-ErbB2 ANTIBODIES

Abstract: The present application discloses treatment of prostate cancer with anti-ErbB2 antibodies.

Description: TREATING PROSTATE CANCER WITH ANTI-ErbB2 ANTIBODIES Field of the Invention The present invention concerns the treatment of prostate cancer with antι-ErbB2 antibodies Background of the Invention The ErbB family of receptor tyrosine kinases are important mediators of cell growth, differentiation and survival The receptor family includes four distinct members including epidermal growth factor receptor (EGFR or ErbBl ), HER2 (ErbB2 or pi 85 '), HER3 (ErbB3) and HER4 (ErbB4 or tyro2) EGFR, encoded by the erbB gene, has been causally implicated in human malignancy In particular, increased expression of EGFR has been observed in breast, bladder, lung, head, neck and stomach cancer as well as glioblastomas Increased EGFR receptor expression is often associated with increased production ol the EGFR hgand, transforming growth tactor alpha (TGF-α), by the same tumor cells resulting in receptor activation by an autocπne stimulatory pathway Baselga and Mendelsohn Pharmac Ther 64 127-154 ( 1994) Monoclonal antibodies directed against the EGFR or its hgands, TGF-α and EGF, have been evaluated as therapeutic agents in the treatment of such malignancies See, e g , Baselga and Mendelsohn , supra, Masui et al Cancer Research 44 1002-1007 (1984), and Wu ef α/ J Chn Invest 95 1897-1905 (1995) The second member of the ErbB family, pi 85 , was originally identified as the product of the transforming gene from neuroblastomas of chemically treated rats The activated form of the neu proto-oncogene results from a point mutation (vahne to glutamic acid) in the transmembrane region of the encoded protein Amplification of the human homolog of neu is observed in breast and ovarian cancers and correlates with a poor prognosis (S amon et al , Science, 235 177-182 (1987), Slamon etal , Scιence, 244 707 712 (1989), and US Pat No 4,968,603) To date, no point mutation analogous to that in the neu proto-oncogene has been reported for human tumors Overexpression of ErbB2 (frequently but not uniformly due to gene amplification) has also been observed in other carcinomas including carcinomas of the stomach, endometπum, salivary gland, lung, kidney, colon, thyroid, pancreas and bladder See, among others, King et al , Science, 229 974 (1985), Yokota et al , Lancet 1 765-767 (1986), Fukushigi et al , Mol Cell Biol , 6 955-958 ( 1986), Geuπn et l , Oncogene Res , 3 21-31 (1988), Cohen et al , Oncogene, 4 81-88 (1989), Yonemura et al , Cancer Res , 51 1034 (1991), Borst et al , G necol Oncol 38 364 ( 1990), Werner et al , Cancer Res , 50 421-425 (1990), Kern et al , Cancer Res , 50 5184 (1990), Park et al , Cancer Res , 49 6605 (1989), Zhau et al , Mol Carctnog , 3 354-357 (1990), Aasland et al Br J Cancer 57 358-363 (1988), Williams et al 59 46-52 (1991), and McCann et al , Cancer, 65 88-92 (1990) ErbB2 may be overexpressed in prostate cancer (Gu et al Cancer Lett 99 185-189 (1996), Ross et al Hum Pathol 28 827-833 (1997), Ross et al Cancer 79 2162-2170 (1997), and Sadasivan et al J Urol 150 126-131 -neu (1993)) Antibodies directed against the rat pl85 and human ErbB 2 protein products have been described Drebin and colleagues have raised antibodies against the rat neu gene product, pi 85 See, for example, Drebin et al , Cell 41 695-706 (1985), Myers et al , Meth Enz i 198 277-290 (1991 ), and W094/22478 Drebin et al Oncogene ! 273-277 (1988) report that mixtures of antibodies reactive with two distinct regions of pi 85 result in synergistic anti-tumor effects on new-transformed NIH-3T3 cells implanted into nude mice See also U S Patent 5,824,31 1 issued October 20, 1998 Hudziak et al , Mol Cell Biol 9(3) 1165-1 172 (1989) describe the generation of a panel of anti ErbB2 antibodies which were characterized using the human breast tumor cell line SKBR3 Relative cell proliferation of the SKBR3 cells following exposure to the antibodies was determined by crystal violet staining of the monolayers after 72 hours Using this assay, maximum inhibition was obtained with the antibody called 4D5 which inhibited cellular proliferation by 56% Other antibodies in the panel reduced cellular proliferation to a lesser extent in this assay The antibody 4D5 was further found to sensitize ErbB2-overexpressιng breast tumor cell lines to the cytotoxic effects of TNF-α See also U S Patent No 5,677,171 issued October 14, 1997 The anti ErbB2 antibodies discussed in Hudziak et al are further characterized in Fendly et al Cancer Research 50 1550-1558 (1990), Kotts et al In Vitro 26(3) 59A (1990), Sarup et al Growth Regulation 1 72-82 (1991 ), Shepard et al J Clin Immunol 1 1 (3) 1 17-127 (1991 ), Kumar et al Mol Cell Biol 1 1 (2) 979-986 (1991), Lewis et al Cancer Immunol Immunother 37 255-263 (1993), Pietras et al Oncogene 9 1829-1838 (1994), Vitetta et al Cancer Research 54 5301-5309 (1994), S wkowski etal J Biol Chem 269(20) 14661-14665 (1994), Scott et al J Biol Chem 266 14300-5 (1991), D'souza et al Proc Natl Acad Set 91 7202-7206 (1994), Lewis et al Cancer Research 56 1457-1465 (1996), and Schaefer et al Oncogene 15 1385-1394 (1997) A recombinant humanized version of the muπne antι-ErbB2 antibody 4D5 (huMAb4D5-8, rhuMAb HER2 or HERCEPTIN ® , U S Patent No 5,821 ,337) is clinically active in patients with ErbB2-overexpressιng metastatic breast cancers that have received extensive prior anti-cancer therapy (Baselga et al , J Clin Oncol \A 1 1-1 A (1996)) HERCEPTIN® received marketing approval from the Food and Drug Administration September 25, 1998 for the treatment of patients with metastatic breast cancer whose tumors overexpress the ErbB2 protein Other antι-ErbB2 antibodies with various properties have been described in Tag abue e? α/ Int J Cancer 47 933-937 (1991), McKenzie ef α/ Oncogene 4 543-548 (1989), Maier e/ α/ CancerRes 51 5361-5369 ( 1991 ), Bacus et al Molecular Carcinogenests 3 350-362 (1990), Stancovski et al PNAS (USA) 88 8691-8695 (1991), Bacus et al Cancer Research 52 2580-2589 (1992), Xu et al Int J Cancer 53 401 -408 (1993), WO94/00136, Kasprzyk erα/ Cancer Research 52 2771-2776 ( 1992), Hancock ef α/ CancerRes 51 4575-4580 (1991 ), Shawver et al Cancer Res 54 1367-1373 (1994), Arteaga et al CancerRes 54 3758-3765 (1994), Harwerth et al J Biol Chem 267 15160-15167 (1992), U S Patent No 5,783,186, and Klapper ef α/ Oncogene 14 2099-2109 (1997) Homology screening has resulted in the identification of two other ErbB receptor family members, ErbB3 (US Pat Nos 5,183,884 and 5,480,968 as well as Kraus et al PNAS (USA) 86 9193-9197 (1989)) and ErbB4 (EP Pat Appln No 599,274, Plowman etal , Proc Natl Acad Set USA, 90 1746-1750 (1993), and Plowman et al , Nature, 366 473-475 (1993)) Both of these receptors display increased expression on at least some breast cancer cell lines The ErbB receptors are generally found in various combinations in cells and heterodimeπzation is thought to increase the diversity of cellular responses to a variety of ErbB ligands (Earp et al Breast Cancer Research and Treatment 35 115-132 (1995)) EGFR is bound by six different ligands, epidermal growth factor (EGF), transforming growth factor alpha (TGF-α), amphireguhn, hepaπn binding epidermal growth factor (HB-EGF), betacellu n and epireguhn (Groenen et al Growth Factors 1 1 235-257 (1994)) A family of heregulin proteins resulting from alternative splicing of a single gene are ligands for ErbB3 and ErbB4 The heregulin family includes alpha, beta and gamma heregulins (Holmes etal , Science, 256 1205-1210 (1992), U S Patent No 5,641 ,869, and Schaefer ef α/ Oncogene 15 1385-1394 (1997)), neu differentiation factors (NDFs), glial growth factors (GGFs), acetylcholine receptor inducing activity (ARIA), and sensory and motor neuron derived factor (SMDF) For a review, see Groenen et al Growth Factors 1 1 235-257 (1994), Lemke, G Molec & Cell Neurosci 1 247-262 (1996) and Lee et al Pharm Rev 47 51-85 (1995) Recently three additional ErbB ligands were identified, neureguhn-2 (NRG-2) which is reported to bind either ErbB3 or ErbB4 (Chang et al Nature 387 509-512 (1997), and Carraway et al Nature 387 512-516 ( 1997)), neuregulιn-3 which binds ErbB4 (Zhang et al PNAS (USA) 94( 18) 9562-7 (1997)), and neuregulιn-4 which binds ErbB4 (Harari et al Oncogene 18 2681-2689 (1999)) HB- EGF, betacelluhn and epireguhn also bind to ErbB4 While EGF and TGFα do not bind ErbB2, EGF stimulates EGFR and ErbB2 to form a heterodimer, which activates EGFR and results in transphosphorylation of ErbB 2 in the heterodimer Dimeπzation and/or transphosphorylation appears to activate the ErbB2 tyrosine kinase See Earp et al , supra Likewise, when ErbB3 is co-expressed with ErbB2, an active signaling complex is formed and antibodies directed against ErbB2 are capable of disrupting this complex (S wkowski etal , J Biol Chem , 269(20) 14661 -14665 ( 1994)) Additionally, the affinity of ErbB3 for heregulin (HRG) is increased to a higher affinity state when co-expressed with ErbB2 See also, Lew et al , Journal of Neuroscience 15 1329-1340 (1995), Mornssey et al , Proc Natl Acad Set USA 92 1431-1435 (1995), andLewιs erα/ , Cancer Res , 56 1457-1465 (1996) with respect to the ErbB2-ErbB3 protein complex ErbB4, like ErbB3, forms an active signaling complex with ErbB2 (Carraway and Cantley, Cell 78 5-8 (1994)) Summary of the Invention In a first aspect, the present invention provides a method of treating prostate cancer (e g androgen independent prostate cancer) in a human comprising administering to the human a therapeutically effective amount of an antibody which binds ErbB2 and blocks hgand activation of an ErbB receptor Preferably, the antibody blocks binding of monoclonal antibody 2C4 to ErbB2 and or blocks TGF-α activation of mitogen-activated protein kinase (MAPK) The invention further provides a method of treating prostate cancer in a human comprising administering to the human therapeutically effective amounts of achemotherapeutic agent (e g a taxane) and of an antibody which binds ErbB2 and blocks hgand activation of an ErbB receptor In another aspect, the invention pertains to an article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antibody which binds ErbB2 and blocks hgand activation of an ErbB receptor, and further comprising a package insert indicating that the composition can be used to treat prostate cancer In addition, the invention pertains to a method of treating androgen dependent prostate cancer in a human comprising administering to the human a therapeutically effective amount of an antibody which binds ErbB2 The method optionally results in an increased prostate specific antigen (PSA) index in the human In one embodiment, the antibody is one, such as monoclonal antibody 4D5 (e g humanized 4D5), which inhibits the growth of cancer cells overexpressing ErbB2 In another embodiment, the antibody is one, like monoclonal antibody 2C4 (e g humanized 2C4), which blocks hgand activation of an ErbB2 receptor The method optionally further comprises administering a chemotherapeutic agent, preferably a taxane, to the human The invention, in a further, aspect, provides an article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antibody which binds ErbB2, and further comprising a package insert indicating that the composition can be used to treat androgen dependent prostate cancer The package insert optionally further indicates treating the patient with a chemotherapeutic agent, such as taxane Brief Description of the Drawings Figures 1 A and IB depict epitope mapping of residues 22-645 within the extracellular domain (ECD) of ErbB2 (ammo acid sequence, including signal sequence, shown in Fig 1A, SEQ ID NO 13) as determined by truncation mutant analysis and site-directed mutagenesis (Nakamura etal J of Virology 67(10) 6179-6191 ( 1993), and Renz et al J Cell Biol 125(6) 1395-1406 (1994)) The various ErbB2-ECD truncations or point mutations were prepared from cDNA using polymerase chain reaction technology The ErbB2 mutants were expressed as gD fusion proteins in a mammalian expression plasmid This expression plasmid uses the cytomegalovirus promoter/enhancer with SV40 termination and polyadenylation signals located downstream of the inserted cDNA Plasmid DNA was transfected into 293 cells One day following transfection, the cells were metabohcally labeled overnight in methionine and cysteine-free, low glucose DMEM containing 1% dialyzed fetal bovine serum and 25 35 35 μCi each of S methionine and S cysteine Supernatants were harvested and either the antι-ErbB2 monoclonal antibodies or control antibodies were added to the supernatant and incubated 2-4 hours at 4 C The complexes were precipitated, applied to a 10-20% Tπcine SDS gradient gel and electrophoresed at 100 V The gel was electroblotted onto a membrane and analyzed by autoradiography As shown in Fig IB, the antι-ErbB2 antibodies 7C2, 7F3, 2C4, 7D3, 3E8, 4D5, 2H1 1 and 3H4 bind various ErbB2 ECD epitopes Figures 2A and 2B show the effect of antι-ErbB2 monoclonal antibodies 2C4 and 7F3 on rHRGβl activation of MCF7 cells Fig 2A shows dose-response curves for 2C4 or 7F3 inhibition of HRG stimulation of 125 tyrosine phosphorylation Fig 2B shows dose-response curves for the inhibition of I-labeled rHRGβl [77 4 binding to MCF-7 cells by 2C4 or 7F3 125 Figure 3 depicts inhibition of specific I-labeled rHRGβ 1 j 77 24 binding to a panel of human tumor cell lines by the antι-ErbB2 monoclonal antibodies 2C4 or 7F3 Monoclonal antibody-controls are isotype-matched 125 muπne monoclonal antibodies that do not block rHRG binding Nonspecific I-labeled rHRGβl )77 2 4 binding was determined from parallel incubations performed in the presence of 100 nM rHRGβl Values for 125 nonspecific I-labeled rHRGβl 177-2 binding were less than 1% of the total for all the cell lines tested Figures 4A and 4B show the effect of monoclonal antibodies 2C4 and 4D5 on proliferation of MDA-MB- 175 (Fig 4A) and SK-BR-3 (Fig 4B) cells MDA-MB-175 and SK-BR-3 cells were seeded in 96 well plates and allowed to adhere for 2 hours Experiment was carried out in medium containing 1 % serum Antι-ErbB2 antibodies or medium alone were added and the cells were incubated for 2 hours at 37°C Subsequently rHRGβl ( InM) or medium alone were added and the cells were incubated for 4 days Monolayers were washed and stained/fixed with 0 5% crystal violet To determine cell proliferation the absorbance was measured at 540 nm Figures 5 A and 5B show the effect of monoclonal antibody 2C4, HERCEPTIN® antibody or an anti-EGFR antibody on heregulin (HRG) dependent association of ErbB2 with ErbB3 in MCF7 cells expressing low/normal levels of ErbB2 (Fig 5 A) and SK-BR-3 cells expressing high levels of ErbB2 (Fig 5B), see Example 2 below Figures 6A and 6B compare the activities of intact muπne monoclonal antibody 2C4 ( u 2C4) and a 125 chimeπc 2C4 Fab fragment Fig 6A shows inhibition of I-HRG binding to MCF-7 cells by chimeπc 2C4 Fab or intact muπne monoclonal antibody 2C4 MCF7 cells were seeded in 24- well plates (1 10 cells/well) and grown to about 85% confluency for two days Binding experiments were conducted as described in Lewis et al Cancer Research 56 1457-1465 (1996) Fig 6B depicts inhibition of rHRGβl activation of pi 80 tyrosine phosphorylation in MCF-7 cells performed as described in Lewis et al Cancer Research 56 1457-1465 (1996) Figures 7A and 7B depict alignments of the amino acid sequences of the variable light (V L ) (Fig 7A) and variable heavy (V H ) (Fig 7B) domains of muπne monoclonal antibody 2C4 (SEQ ID Nos 1 and 2, respectively), V L and V H domains of humanized Fab version 574 (SEQ ID Nos 3 and 4, respectively), and human V L and V H consensus frameworks (hum κl , light kappa subgroup I, humlll, heavy subgroup III) (SEQ ID Nos 5 and 6, respectively) Asterisks identify differences between humanized Fab version 574 and muπne monoclonal antibody 2C4 or between humanized Fab version 574 and the human framework Complementarity Determining Regions (CDRs) are in brackets Figures 8A to C show binding of chimeπc Fab 2C4 (Fab v 1 ) and several humanized 2C4 variants to ErbB2 extracellular domain (ECD) as determined by ELISA in Example 3 Figure 9 is a ribbon diagram of the V L and V H domains of monoclonal antibody 2C4 with white CDR backbone labeled (LI , L2, L3, HI , H2, H3) V H side chains evaluated by mutagenesis during humanization (see Example 3, Table 2) are also shown Figure 10 depicts the effect of monoclonal antibody 2C4 or HERCEPTIN® on EGF, TGF-α, or HRG- mediated activation of mitogen-activated protein kinase ( MAPK) Figures 1 1 A to H depict response of xenograft tumors to HERCEPTIN® (H,β), control (C, o), TAXOL® (T, A) and combination HERCEPTINΘ/TAXOL® (H/T, 0) treatment The response of the androgen independent tumors CWR22R and CWRSA6 (Figs 1 1 A and B, respectively) and the androgen dependent tumors CWR22 and LNCaP (Figs 11C and D, respectively) to HERCEPTIN® and control are shown The response of the tumors to HERCEPTIN®, TAXOL®, HERCEPTIN®/TAXOL® and control are shown in Fig 1 IE (CWR22), Fig 1 IF (LNCaP), Fig 1 1G (CWR22R), and Fig 11H (CWRSA6) Results are given as mean tumor volume +/- SE Figures 12A and 12B depict relative prostate specific antigen (PSA) index response of animals with androgen dependent prostate cancer xenografts treated with HERCEPTIN® In Fig 12A, PSA index was measured in the LNCaP xenograft model prior to treatment and at days 9 and 21 after initiating treatment and expressed as relative to pretreatment values In Fig 12B, PSA index was measured in the CWR22 xenograft model prior to treatment and at days 9 and 21 after initiating treatment and expressed as relative to pretreatment values Results are given as mean relative PSA +/- SE Figure 13 depicts response of the androgen dependent tumor CWR22 to therapy with control antibody (C, A), HERCEPTIN® (H, o) or monoclonal antibody 2C4 (2, ■) Administration of 2C4 designated by *, administration of HERCEPTIN® designated by + Figure 14 depicts response of the androgen dependent tumor CWR22 to therapy with TAXOL® alone (T, o), monoclonal antibody 2C4 alone (2, ■) or a combination of monoclonal antibody 2C4 and TAXOL® (2/T, A) Administration of 2C4 designated by *, administration of TAXOL® (6 25 mg/kg) designated by + Figure 15 depicts response of the androgen independent tumor CWR22R to therapy with control antibody (C, A), HERCEPTIN® (H, o) or monoclonal antibody 2C4 (2, ■) Administration of monoclonal antibody 2C4 designated by +, administration of HERCEPTIN® designated by + Figure 16 depicts response of the androgen independent tumor CWR22R to therapy with TAXOL® alone (T, o), monoclonal antibody 2C4 alone (2, ■) or a combination of monoclonal antibody 2C4 and TAXOL® (2 T, A) Administration of 2C4 designated by *, administration of TAXOL® (6 25 mg/kg) designated by + Figure 17 depicts response of the androgen independent tumor CWRS A6 to therapy with control antibody (C, A), HERCEPTIN® (H, o) or monoclonal antibody 2C4 (2, ■) Administration of monoclonal antibody 2C4 designated by +, administration of HERCEPTIN® designated by + Figure 18 depicts response of the androgen independent tumor CWRS A6 to therapy with TAXOL® alone (T, o), monoclonal antibody 2C4 alone (2, ■) or a combination of monoclonal antibody 2C4 and TAXOL® (2/T, A) Administration of 2C4 designated by *, administration of TAXOL® (6 25 mg/kg) designated by + Figure 19 depicts relative TGF-α mRNA expression by CWR22R or CWR22 cells as determined by Real Time Quantitative PCR Figure 20 depicts relative HB-EGF mRNA expression by CWR22R or CWR22 cells as determined by Real Time Quantitative PCR Figure 21 depicts the effect of antι-ErbB2 monoclonal antibody treatment on the growth of prostate cancer xenograf ts Tumor growth is normalized to control tumors at the end of each experiment when control animals were sacrificed The values shown for CWR22 correspond to day 23 after the formation of a palpable tumor, for LNCaP, to day 51 , for CWR22R, to day 22, for CWR22SA6, to day 33 Figure 22 shows the effect of antι-ErbB2 monoclonal antibody treatment on PSA index PSA index is defined as the amount of serum PSA normalized to tumor volume Figure 23 evaluates the activity of recomb ant humanized monoclonal antibody (rhuMAb 2C4), a pegylated Fab fragment thereof, and munne 2C4, on the CWR22R androgen independent prostate xenograft Figure 24 depicts dose response of rhuMAb 2C4 on the CWR22R androgen independent prostate xenograft Figure 25 depicts dose response of rhuMAb 2C4 on the MSKPC6 androgen independent prostate xenograft Figure 26 depicts 2C4 and 7C2 dose response in androgen dependent prostate xenograft (CWR22) Figure 27 depicts tumor volume in CWR22R xenografts treated with TAXOL® and antι-ErbB2 antibodies 2C4 and 7C2 Detailed Description of the Preferred Embodiments I. Definitions An "ErbB receptor" is a receptor protein tyrosine kinase which belongs to the ErbB receptor family and includes EGFR, ErbB2, ErbB3 and ErbB4 receptors and other members of this family to be identified in the future The ErbB receptor will generally comprise an extracellular domain, which may bind an ErbB hgand, a lipophilic transmembrane domain, a conserved intracellulartyrosine kinase domain, and a carboxyl-terminal signaling domain harboring several tyrosine residues which can be phosphorylated The ErbB receptor may be a "native sequence" ErbB receptor or an "amino acid sequence variant" thereof Preferably the ErbB receptor is native sequence human ErbB receptor The terms "ErbB 1 ", "epidermal growth factor receptor" and "EGFR" are used interchangeably herein and refer to EGFR as disclosed, for example, in Carpenter et al Ann Rev Biochem 56 881-914 (1987), including naturally occurring mutant forms thereof (e g a deletion mutant EGFR as in Humphrey etal PNAS (USA) ST 4207- 421 1 (1990)) erbB\ refers to the gene encoding the EGFR protein product The expressions "ErbB2 " and "HER2 " are used interchangeably herein and refer to human HER2 protein described, for example, in Semba et al , PNAS (USA) 82 6497-6501 (1985) and Yamamoto et al Nature 319 230- 234 (1986) (Genebank accession number X03363) The term ' erbB2 " refers to the gene encoding human ErbB2 and "neu " refers to the gene encoding rat pi 85 Preferred ErbB2 is native sequence human ErbB2 "ErbB3 ' and "HER3 " refer to the receptor polypeptide as disclosed, for example, in US Pat Nos 5,183,884 and 5,480,968 as well as Kraus et al PNAS (USA) 86 9193-9197 (1989) The terms "ErbB4 " and "HER4 " herein refer to the receptor polypeptide as disclosed, for example, in EP Pat Appln No 599,274, Plowman et al , Proc Natl Acad Sci USA, 90 1746-1750 (1993), and Plowman et al Nature, 366 473-475 ( 1993), including isoforms thereof, e g , as disclosed in W099/19488 published April 22, 1999 By "ErbB gand" is meant a polypeptide which binds to and or activates an ErbB receptor The ErbB hgand of particular interest herein is a native sequence human ErbB hgand such as epidermal growth factor (EGF) (Savage et al , J Biol Chem 247 7612-7621 (1972)), transforming growth factor alpha (TGF-α) (Marquardt et al , Science 223 1079-1082 (1984)), amphireguhn also known as schwanoma or keratinocyte autocπne growth factor (Shoyab etal Science lM, 1074-1076 (1989), Kimura etal Nature 348 257-260(1990), and Cook etal Mol Cell Biol 1 1 2547-2557 (1991)), betacelluhn (Shing et al , Science 259 1604-1607 (1993), and Sasada et al Biochem Btophys Res Commun 190 1173 (1993)), heparin-binding epidermal growth factor (HB-EGF) (Higashiyama etal , Science 251 936-939 (1991)), epireguhn (Toyoάa etal , J Biol Chem 270 7495-7500 (1995), and Komurasaki et al Oncogene 15 2841-2848 (1997)), a heregulin (see below), neureguhn-2 (NRG-2) (Carraway et al , Nature 387 512-516 (1997)), neureguhn-3 (NRG-3) (Zhang et al , Proc Natl Acad Set 94 9562-9567 (1997)), neureguhn-4 (NRG-4) (Haraπ ef α/ Oncogene 18 2681-2689 (1999)), or cπpto (CR-l) (Kannan erα/ J Biol Chem 272(6) 3330-3335 (1997)) ErbB ligands which bind EGFR include EGF, TGF-α, amphireguhn, betacelluhn, HB-EGF and epireguhn ErbB ligands which bind ErbB3 include heregulins ErbB ligands capable of binding ErbB4 include betacelluhn, epireguhn, HB-EGF, NRG-2, NRG-3, NRG-4 and heregulins "Heregulin" (HRG) when used herein refers to a polypeptide encoded by the heregulin gene product as disclosed in U S Patent No 5,641, 869 or Marchionm etal , Nature, 362 312-318 (1993) Examples of heregulins include hereguhn-α, hereguhn-βl , heregulιn-β2 and hereguhn-β3 (Holmes et al , Science, 256 1205-1210 (1992), and U S Patent No 5,641,869), neu differentiation factor (NDF) (Peles et al Cell 69 205-216 (1992)), acetylcholine receptor-inducing activity (ARIA) (Falls etal Cell 72 801-815 (1993)), ghal growth factors (GGFs) (Marchionm et al , Nature, 362 312-318 (1993)), sensory and motor neuron derived factor (SMDF) (Ho et al J Biol Chem 270 14523-14532 (1995)), γ-hereguhn (Schaefer et al Oncogene 15 1385-1394 (1997)) The term includes biologically active fragments and/or amino acid sequence variants of a native sequence HRG polypeptide, such as an EGF-hke domain fragment thereof (e g HRGβl j7 _ 24 ) An "ErbB hetero-ohgomer" herein is a noncovalently associated o gomer comprising at least two different ErbB receptors Such complexes may form when a cell expressing two or more ErbB receptors is exposed to an ErbB hgand and can be isolated by immunoprecipitation and analyzed by SDS-PAGE as described in Shwkowski etal , J Biol Chem , 269(20) 14661-14665 (1994), for example Examples of such ErbB hetero-o gomers include EGFR-ErbB2, ErbB2-ErbB3 and ErbB3-ErbB4 complexes Moreover, the ErbB hetero-ohgomer may comprise two or more ErbB2 receptors combined with a different ErbB receptor, such as ErbB3, ErbB4 or EGFR Other proteins, such as a cytokine receptor subunit (e g gpl30) may be included in the hetero-ohgomer By "hgand activation of an ErbB receptor" is meant signal transduction (e g that caused by an intracellular kinase domain of an ErbB receptor phosphorylating tyrosine residues in the ErbB receptor or a substrate polypeptide) mediated by ErbB hgand binding to a ErbB hetero-ohgomer comprising the ErbB receptor of interest Generally, this will involve binding of an ErbB hgand to an ErbB hetero-ohgomer which activates a kinase domain of one or more of the ErbB receptors in the hetero-ohgomer and thereby results in phosphorylation of tyrosine residues in one or more of the ErbB receptors and or phosphorylation of tyrosine residues in additional substrate polypeptides's) ErbB receptor activation can be quantified using various tyrosine phosphorylation assays A "native sequence" polypeptide is one which has the same amino acid sequence as a polypeptide (e g , ErbB receptor or ErbB hgand) derived from nature Such native sequence polypeptides can be isolated from nature or can be produced by recombinant or synthetic means Thus, a native sequence polypeptide can have the amino acid sequence of naturally occurring human polypeptide, muπne polypeptide, or polypeptide from any other mammalian species The term "amino acid sequence variant" refers to polypeptides having amino acid sequences that differ to some extent from a native sequence polypeptide Ordinarily, amino acid sequence variants will possess at least about 70% homology with at least one receptor binding domain of a native ErbB hgand or with at least one hgand binding domain of a native ErbB receptor, and preferably, they will be at least about 80%, more preferably at least about 90% homologous with such receptor or hgand binding domains The amino acid sequence variants possess substitutions, deletions, and or insertions at certain positions within the amino acid sequence of the native amino acid sequence "Homology" is defined as the percentage of residues in the amino acid sequence variant that are identical after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent homology Methods and computer programs for the alignment are well known in the art One such computer program is "Align 2", authored by Genentech, Inc , which was filed with user documentation in the United States Copyright Office, Washington, DC 20559, on December 10, 1991 The term "antibody" herein is used in the broadest sense and specifically covers monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e g bispecific antibodies) formed from at least two intact antibodies, and antibody fragments, so long as they exhibit the desired biological activity The term ' monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, j e , the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts Monoclonal antibodies are highly specific, being directed against a single antigenic site Furthermore, in contrast to polyclonal antibody preparations which include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen In addition to their specificity, the monoclonal antibodies are advantageous in that they may be synthesized uncontaminated by other antibodies The modifier "monoclonal' indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method For example, the monoclonal antibodies to be used in accordance with the present invention may be made by the hybπdoma method first described by Kohler et al , Nature, 256 495 (1975), or may be made by recombinant DNA methods (see, e g , U S PatentNo 4,816,567) The "monoclonal antibodies" may also be isolated from phage antibody libraries using the techniques described in Clackson etal , Nature, 352 624-628 ( 1991 ) and Marks etal , J Mol Biol , 222 581 -597 (1991 ), for example The monoclonal antibodies herein specifically include "chimeπc' antibodies in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chaιn(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U S Patent No 4,816,567, and Morrison et al , Proc Natl Acad Sci USA, 81 6851-6855 ( 1984)) Chimeπc antibodies of interest herein include "pπmatized" antibodies comprising vanable domain antigen- binding sequences derived from a non-human primate (e g Old World Monkey, Ape etc) and human constant region sequences "Antibody fragments" comprise a portion of an intact antibody, preferably comprising the antigen-binding or variable region thereof Examples of antibody fragments include Fab, Fab', F(ab') 2 , and Fv fragments, diabodies, linear antibodies, single-chain antibody molecules, and multispecific antibodies formed from antibody fragment(s) An "intact" antibody is one which comprises an antigen-binding variable region as well as a light chain constant domain (C L ) and heavy chain constant domains, C H 1 , C H 2 and C H 3 The constant domains may be native sequence constant domains (e g human native sequence constant domains) or amino acid sequence variant thereof Preferably, the intact antibody has one or more effector functions Antibody "effector functions" refer to those biological activities attributable to the Fc region (a native sequence Fc region or amino acid sequence variant Fc region) of an antibody Examples of antibody effector functions include Clq binding, complement dependent cytotoxicity, Fc receptor binding, antibody-dependent cell- mediated cytotoxicity (ADCC), phagocytosis, down regulation of cell surface receptors (e g B cell receptor, BCR), etc Depending on the amino acid sequence of the constant domain of their heavy chains, intact antibodies can be assigned to different "classes" There are five major classes of intact antibodies IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into "subclasses" (isotypes), e g , IgGl, IgG2, IgG3, IgG4, IgA, and IgA2 The heavy-chain constant domains that correspond to the different classes of antibodies are called α, δ, ε, γ, and μ, respectively The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known "Antibody-dependent cell-mediated cytotoxicity" and "ADCC" refer to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e g Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell The primary cells for mediating ADCC, NK cells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII and FcγRIII FcR expression on hematopoietic cells in summarized is Table 3 on page 464 of Ravetch and Kmet, Annu Rev Immunol 9 457-92 ( 1991 ) To assess ADCC activity of a molecule of interest, an in vitro ADCC assay, such as that described in US Patent No 5,500,362 or 5,821 ,337 may be performed Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e g , in a animal model such as that disclosed in Clynes et al PNAS (USA) 95 652-656 ( 1998) "Human effector cells" are leukocytes which express one or more FcRs and perform effector functions Preferably, the cells express at least FcγRIII and perform ADCC effector function Examples of human leukocytes which mediate ADCC include peripheral blood mononuclear cells (PBMC), natural killer (NK) cells, monocytes, cytotoxic T cells and neutrophils, with PBMCs and NK cells being preferred The effet tor ceils may be isolated from a native source thereof, e g from blood or PBMCs as described herein The terms "Fc receptor" or "FcR" are used to describe a receptor that binds to the Fc region of an antibody The preferred FcR is a native sequence human FcR Moreover, a preferred FcR is one which binds an IgG antibody (a gamma receptor) and includes receptors of the FcγRI, FcγRII, and Fcγ RIII subclasses, including allehc variants and alternatively spliced forms of these receptors FcγRII receptors include FcγRIIA (an "activating receptor ') and FcγRIIB (an "inhibiting receptor"), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof Activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif (IT AM) in its cytoplasmic domain Inhibiting receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibition motif (IΗM) in its cytoplasmic domain (see review M in Daeron, Annu Rev Immunol 15 203-234 (1997)) FcRs are reviewed in Ravetch and Kinet, Annu Rev Immunol 9 457-92 (1991), Capel et al Immunomethods 4 25-34 (1994), and de Haas etal , J Lab Clin Med 126 330-41 (1995) Other FcRs, including those to be identified in the future, are encompassed by the term "FcR" herein The term also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al , J Immunol 1 17 587 (1976) and Ki et al . J Immunol 24 249 (1994)) "Complement dependent cytotoxicity" or "CDC" refers to the ability of a molecule to lyse a target in the presence of complement The complement activation pathway is initiated by the binding of the first component of the complement system (Clq) to a molecule (e g an antibody) complexed with a cognate antigen To assess complement activation, a CDC assay, e g as described in Gazzano-Santoro et al , J Immunol Methods 202 163 ( 1996), may be performed "Native antibodies" are usually heterotetrameπc glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chains of different immunoglobulin isotypes Each heavy and light chain also has regularly spaced intrachain disulfide bridges Each heavy chain has at one end a variable domain (V H ) followed by a number of constant domains Each light chain has a variable domain at one end (V L ) and a constant domain at its other end The constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light-chain variable domain is aligned with the variable domain of the heavy chain Particular amino acid residues are believed to form an interface between the light chain and heavy chain variable domains The term "variable" refers to the fact that certain portions of the variable domains differ extensively in sequence among antibodies and are used in the binding and specificity of each particular antibody for its particular antigen However, the variability is not evenly distributed throughout the variable domains of antibodies It is concentrated in three segments called hypervaπable regions both in the light chain and the heavy chain variable domains The more highly conserved portions of variable domains are called the framework regions (FRs) The variable domains of native heavy and light chains each comprise four FRs, largely adopting a β-sheet configuration, connected by three hypervaπable regions, which form loops connecting, and in some cases forming part of, the β- sheet structure The hypervaπable regions in each chain are held together in close proximity by the FRs and, with the hypervaπable regions from the other chain, contribute to the formation of the antigen-binding site of antibodies (see Kabat et al , Sequences of Proteins of Immunological Interest, 5th Ed Public Health Service, National Institutes of Health, Bethesda, MD ( 1991 )) The constant domains are not involved directly in binding an antibody to an antigen, but exhibit various effector functions, such as participation of the antibody in antibody dependent cellular cytotoxicity (ADCC) The term "hypervaπable region" when used herein refers to the amino acid residues of an antibody which are responsible for antigen-binding The hypervaπable region generally comprises amino acid residues from a "complementarity determining region" or "CDR" (e g residues 24-34 (LI), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35 (HI ), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain, Kabat et al , Sequences of Proteins of Immunological Interest, 5th Ed Public Health Service, National Institutes of Health, Bethesda, MD (1991)) and/or those residues from a "hypervaπable loop" (e g residues 26-32 (LI), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (HI ). 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain, Chothia and LeskJ Mol Biol 196 901-917 (1987)) "Framework Region" or "FR" residues are those variable domain residues other than the hypervariable region residues as herein defined Papain digestion of antibodies produces two identical antigen-binding fragments, called "Fab" fragments, each with a single antigen-binding site, and a residual "Fc" fragment, whose name reflects its ability to crystallize readily Pepsin treatment yields an F(ab') 2 fragment that has two antigen-binding sites and is still capable of cross- linking antigen "Fv" is the minimum antibody fragment which contains a complete antigen-recognition and antigen- binding site This region consists of a dimer of one heavy chain and one light chain variable domain in tight, non- covalent association It is in this configuration that the three hypervaπable regions of each variable domain interact to define an antigen-binding site on the surface of the V H -V L dimer Collectively, the six hypervanable regions confer antigen-binding specificity to the antibody However, even a single variable domain (or half of an Fv comprising only three hypervanable regions specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site The Fab fragment also contains the constant domain of the light chain and the first constant domain (CH 1 ) of the heavy chain Fab' fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy chain CHI domain including one or more cysteines from the antibody hinge region Fab'-SH is the designation herein for Fab' in which the cysteine resιdue(s) of the constant domains bear at least one free thiol group F(ab ) 2 antibody fragments originally were produced as pairs of Fab' fragments which have hinge cysteines between them Other chemical couplings of antibody fragments are also known The "light chains" of antibodies from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (K) and lambda (λ), based on the amino acid sequences of their constant domains "Single-chain Fv" or "scFv" antibody fragments comprise the V H and V L domains of antibody, wherein these domains are present in a single polypeptide chain Preferably, the Fv polypeptide further comprises a polypeptide linker between the V H and V L domains which enables the scFv to form the desired structure for antigen binding For a review of scFv see Pluckthun in 77ιe Pharmacology of Monoclonal Antibodies, vol 1 13, Rosenburg and Moore eds , Spπnger-Verlag, New York, pp 269-315 ( 1994) Antι-ErbB2 antibody scFv fragments are described in W093/16185, U S Patent No 5,571 ,894, and U S Patent No 5,587,458 The term "diabodies" refers to small antibody fragments with two antigen-binding sites, which fragments comprise a variable heavy domain (V H ) connected to a variable light domain (V L ) in the same polypeptide chain (V H - V L ) By using a linker that is too short to allow pairing between the two domains on the same chain, the domains are forced to pair with the complementary domains of another chain and create two antigen-binding sites Diabodies are described more fully in, for example, EP 404,097, WO 93/1 1 161 , and Holhnger et al , Proc Natl Acad Set USA, 90 6444-6448 (1993) "Humanized" forms of non-human (e g rodent) antibodies are chimeπc antibodies that contain minimal sequence derived from non-human lmmunoglobu n For the most part, humanized antibodies are human lmmunoglobuhns (recipient antibody) in which residues from a hypervanable region of the recipient are replaced by residues from a hypervanable region of a non-human species (donor antibody) such as mouse, rat, rabbit or nonhuman primate having the desired specificity, affinity, and capacity In some instances, framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues Furthermore, humanized antibodies may comprise residues that are not found in the recipient antibody or in the donor antibody These modifications are made to further refine antibody performance In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervanable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin For further details, see Jones et al , Nature 321 522-525 (1986), Riechmann etal , Nature 332 323-329 (1988), and Presta, Curr Op Struct Biol 2 593-596 ( 1992) Humanized antι-ErbB2 antibodies include huMAb4D5 1 , huMAb4D5-2, huMAb4D5-3, huMAb4D5-4, huMAb4D5-5, huMAb4D5-6, huMAb4D5-7 and huMAb4D5-8 (HERCEPTIN®) as described in Table 3 of U S Patent 5,821 ,337 expressly incorporated herein by reference, humanized 520C9 (W093/21319) and humanized 2C4 as described hereinbelow An ' isolated" antibody is one which has been identified and separated and/or recovered from a component of its natural environment Contaminant components of its natural environment are materials which would interfere with diagnostic or therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or nonproteinaceous solutes In preferred embodiments, the antibody will be purified (1 ) to greater than 95% by weight of antibody as determined by the Lowry method, and most preferably more than 99% by weight, (2) to a degree sufficient to obtain at least 15 residues of N-teπrunal or internal amino acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-PAGE under reducing or nonreducing conditions using Coomassie blue or, preferably, silver stain Isolated antibody includes the antibody in situ within recombinant cells since at least one component of the antibody's natural environment will not be present Ordinarily, however, isolated antibody will be prepared by at least one purification step An antibody "which binds" an antigen of interest, e g ErbB2 antigen, is one capable of binding that antigen with sufficient affinity such that the antibody is useful as a therapeutic agent in targeting a cell expressing the antigen Where the antibody is one which binds ErbB2, it will usually preferentially bind ErbB2 as opposed to other ErbB receptors, and may be one which does not significantly cioss-react with other proteins such as EGFR, ErbB3 or ErbB4 In such embodiments, the extent of binding of the antibody to these non-ErbB2 proteins (e g cell surface binding to endogenous receptor) will be less than 10% as determined by fluorescence activated cell sorting (FACS) analysis or radioimmunoprecipitation (RIA) Sometimes, the antι-ErbB2 antibody will not significantly cross-react with the rat neu protein, e g , as described in Schecter et al Nature 312 513 (1984) and Drebin et al , Nature 312 545-548 (1984) An antibody which "blocks" hgand activation of an ErbB receptor is one which reduces or prevents such activation as hereinabove defined, wherein the antibody is able to block hgand activation of the ErbB receptor substantially more effectively than monoclonal antibody 4D5, e g about as effectively as monoclonal antibodies 7F3 or 2C4 or Fab fragments thereof and preferably about as effectively as monoclonal antibody 2C4 or a Fab fragment thereof For example, the antibody that blocks hgand activation of an ErbB receptor may be one which is about 50-100% more effective than 4D5 at blocking formation of an ErbB hetero-ohgomer Blocking of hgand activation of an ErbB receptor can occur by any means, e g by interfering with gand binding to an ErbB receptor, ErbB complex formation, tyrosine kinase activity of an ErbB receptor in an ErbB complex and/or phosphorylation of tyrosine kinase resιdue(s) in or by an ErbB receptor Examples of antibodies which block hgand activation of an ErbB receptor include monoclonal antibodies 2C4 and 7F3 (which block HRG activation of ErbB2/ErbB3 and ErbB2/ErbB4 hetero-ohgomers, and EGF, TGF-α, amphireguhn, HB-EGF and/or epireguhn activation of an EGFR/ErbB2 hetero-ohgomer), and L26, L96 and L288 antibodies (Klapper et al Oncogene 14 2099-2109 (1997)), which block EGF and NDF binding to T47D cells which express EGFR, ErbB2, ErbB3 and ErbB4 An antibody having a "biological characteristic" of a designated antibody, such as the monoclonal antibody designated 2C4, is one which possesses one or more of the biological characteristics of that antibody which distinguish it from other antibodies that bind to the same antigen (e g ErbB2) For example, an antibody with a biological characteristic of 2C4 may block HRG activation of an ErbB hetero-ohgomer comprising ErbB2 and ErbB3 or ErbB4, block EGF, TGF-α, HB-EGF, epireguhn and or amphireguhn activation of an ErbB receptor comprising EGFR and ErbB2, block EGF, TGF-α and/or HRG mediated activation of MAPK, and/or bind the same epitope in the extracellular domain of ErbB2 as that bound by 2C4 (e g which blocks binding of monoclonal antibody 2C4 to ErbB2) Unless indicated otherwise, the expression "monoclonal antibody 2C4" refers to an antibody that has antigen binding residues of, or derived from, the muπne 2C4 antibody of the Examples below For example, the monoclonal antibody 2C4 may be muπne monoclonal antibody 2C4 or a variant thereof, such as a humanized 2C4, possessing antigen binding amino acid residues of muπne monoclonal antibody 2C4 Examples of humanized 2C4 antibodies are provided in Example 3 below Unless indicated otherwise, the expression "rhuMAb 2C4" when used herein refers to an antibody comprising the variable light (V L ) and variable heavy (V H ) sequences of SEQ ID Nos 3 and 4, respectively, fused to human light and heavy IgG l (non-A allotype) constant region sequences optionally expressed by a Chinese Hamster Ovary (CHO) cell Unless indicated otherwise, the term "monoclonal antibody 4D5" refers to an antibody that has antigen binding residues of, or derived from, the muπne 4D5 antibody (ATCC CRL 10463) For example, the monoclonal antibody 4D5 may be muπne monoclonal antibody 4D5 or a variant thereof, such as a humanized 4D5, possessing antigen binding residues of muπne monoclonal antibody 4D5 Exemplary humanized 4D5 antibodies include huMAb4D5-l , huMAb4D5-2, huMAb4D5-3, huMAb4D5-4, huMAb4D5-5, huMAb4D5-6, huMAb4D5-7 and huMAb4D5-8 (HERCEPTIN®) as in US Patent No 5,821 ,337, with huMAb4D5-8 (HERCEPTIN®) being a preferred humanized 4D5 antibody A "growth inhibitory agent" when used herein refers to a compound or composition which inhibits growth of a cell, especially an ErbB expressing cancer cell either in viti o or in vivo Thus, the growth inhibitory agent may be one which significantly reduces the percentage of ErbB expressing cells in S phase Examples of growth inhibitory agents include agents that block cell cycle progression (at a place other than S phase), such as agents that induce Gl aπest and M-phase arrest Classical M-phase blockers include the vincas (vincπstine and vinblastine), taxanes, and topo II inhibitors such as doxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin Those agents that arrest Gl also spill over into S-phase arrest, for example, DNA alkylating agents such as tamoxifen, prednisone, dacarbazine, mechlorethamine, cisplatin, methotrexate, 5-fluorouracιl, and ara-C Further information can be found in The Molecular Basis of Cancer, Mendelsohn and Israel, eds , Chapter 1, entitled "Cell cycle regulation, oncogenes, and antineoplastic drugs" by Murakami etal (WB Saunders Philadelphia, 1995), especially P 13 Examples of "growth inhibitory" antibodies are those which bind to ErbB2 and inhibit the growth of cancer cells overexpressing ErbB2 Preferred growth inhibitory antι-ErbB2 antibodies inhibit growth of SK-BR-3 breast tumor cells in cell culture by greater than 20%, and preferably greater than 50% (e g from about 50% to about 100%) at an antibody concentration of about 0 5 to 30 μg/ml, where the growth inhibition is determined six days after exposure of the SK-BR-3 cells to the antibody (see U S Patent No 5,677,171 issued October 14, 1997) The SK-BR-3 cell growth inhibition assay is described in more detail in that patent and hereinbelow An antibody which "induces cell death" is one which causes a viable cell to become nonviable The cell is generally one which expresses the ErbB2 receptor, especially where the cell overexpresses the ErbB2 receptor Preferably, the cell is a cancer cell, e g a breast, ovarian, stomach, endometπal, salivary gland, lung, kidney, colon, thyroid, pancreatic or bladder cell In vitro, the cell may be a SK-BR-3, BT474, Calu 3, MDA-MB-453, MDA-MB- 361 or SKOV3 cell Cell death in vitro may be determined in the absence of complement and immune effector cells to distinguish cell death induced by antibody-dependent cell-mediated cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) Thus, the assay for cell death may be performed using heat inactivated serum (t e in the absence of complement) and in the absence of immune effector cells To determine whether the antibody is able to induce cell death, loss of membrane integrity as evaluated by uptake of propidium iodide (PI), trypan blue (see Moore et αl Cytotechnology 17 1 -1 1 (1995)) or 7AAD can be assessed relative to untreated cells Preferred cell death-inducing antibodies are those which induce PI uptake in the PI uptake assay in BT474 cells (see below) An antibody which "induces apoptosis" is one which induces programmed cell death as determined by binding of annexin V, fragmentation of DNA, cell shrinkage, dilation of endoplasmic reticulum, cell fragmentation, and/or formation of membrane vesicles (called apoptotic bodies) The cell is usually one which overexpresses the ErbB2 receptor Preferably the cell is a tumor cell, e g abreast, ovarian, stomach, endometπal, salivary gland, lung, kidney, colon, thyroid, pancreatic or bladder cell In vitro, the cell may be a SK-BR-3, BT474, Calu 3 cell, MDA- MB-453, MDA-MB-361 orSKOV3 cell Various methods are available for evaluating the cellular events associated with apoptosis For example, phosphatidyl seπne (PS) translocation can be measured by annexin binding, DNA fragmentation can be evaluated through DNA laddering, and nuclear/chromatin condensation along with DNA fragmentation can be evaluated by any increase in hypodiploid cells Preferably, the antibody which induces apoptosis is one which results in about 2 to 50 fold, preferably about 5 to 50 fold, and most preferably about 10 to 50 fold, induction of annexin binding relative to untreated cell in an annexin binding assay using BT474 cells (see below) Sometimes the pro-apoptotic antibody will be one which further blocks ErbB hgand activation of an ErbB receptor (e g 7F3 antibody), t e the antibody shares a biological characteristic with monoclonal antibody 2C4 In other situations, the antibody is one which does not significantly block ErbB hgand activation of an ErbB receptor (e g 7C2) Further, the antibody may be one like 7C2 which, while inducing apoptosis, does not induce a large reduction in the percent of cells in S phase (e g one which only induces about 0-10% reduction in the percent of these cells relative to control) The "epitope 2C4" is the region in the extracellular domain of ErbB2 to which the antibody 2C4 binds In order to screen for antibodies which bind to the 2C4 epitope, a routine cross-blocking assay such as that described in Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988), can be performed Alternatively, epitope mapping can be performed to assess whether the antibody binds to the 2C4 epitope of ErbB2 (e g any one or more residues in the region from about residue 22 to about residue 584 of ErbB2, inclusive, see Figs 1A-B) The "epitope 4D5" is the region in the extracellular domain of ErbB2 to which the antibody 4D5 (ATCC CRL 10463) binds This epitope is close to the transmembrane domain of ErbB2 To screen for antibodies which bind to the 4D5 epitope, a routine cross-blocking assay such as that described in Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988), can be performed Alternatively, epitope mapping can be performed to assess whether the antibody binds to the 4D5 epitope of ErbB2 (e g any one or more residues in the region from about residue 529 to about residue 625, inclusive, see Figs 1 A-B) The "epitope 3H4" is the region in the extracellular domain of ErbB2 to which the antibody 3H4 binds This epitope includes residues from about 541 to about 599, inclusive, in the amino acid sequence of ErbB2 extracellular domain, see Figs 1 A-B The ' epitope 7C2/7F3" is the region at the N terminus of the extracellular domain of ErbB2 to which the 7C2 and/or 7F3 antibodies (each deposited with the ATCC, see below) bind To screen for antibodies which bind to the 7C2/7F3 epitope, a routine cross-blocking assay such as that described in Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988), can be performed Alternatively, epitope mapping can be performed to establish whether the antibody binds to the 7C2/7F3 epitope on ErbB2 (e g any one or more of residues in the region from about residue 22 to about residue 53 of ErbB2, see Figs 1 A-B) "Treatment" refers to both therapeutic treatment and prophylactic or preventative measures Those in need of treatment include those already with the disorder as well as those in which the disorder is to be prevented Hence, the mammal to be treated herein may have been diagnosed as having the disorder or may be predisposed or susceptible to the disorder "Mammal" for purposes of treatment refers to any animal classified as a mammal, including humans, domestic and farm animals, and zoo, sports, or pet animals, such as dogs, horses, cats, cows, etc Preferably, the mammal is human The term "therapeutically effective amount" refers to an amount of a drug effective to treat a disease or disorder in a mammal In the case of cancer, the therapeutically effective amount of the drug may reduce the number of cancer cells, reduce the tumor size, inhibit (i e , slow to some extent and preferably stop) cancer cell infiltration into peripheral organs, inhibit (t e , slow to some extent and preferably stop) tumor metastasis, inhibit, to some extent, tumor growth, and/or relieve to some extent one or more of the symptoms associated with the cancer To the extent the drug may prevent growth and/or kill existing cancer cells, it may be cytostatic and/or cytotoxic For cancer therapy, efficacy can, for example, be measured by assessing the time to disease progression ( I IP) and/or determining the response rate (RR) The terms "cancer" and "cancerous" refer to or describe the physiological condition in mammals that is typically characterized by unregulated cell growth Examples of cancer include, but are not limited to, carcinoma, lymphoma, blastoma, sarcoma, and leukemia or lymphoid malignancies More particular examples of such cancers include squamous cell cancer (e g epithelial squamous cell cancer), lung cancer including small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung and squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer, colon cancer, rectal cancer, colorectal cancer, endometrial or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma, as well as head and neck cancer An "ErbB-expressing cancer" is one comprising cells which have ErbB protein present at their cell surface An "ErbB2-expressιng cancer" is one which produces sufficient levels of ErbB2 at the surface of cells thereof, such that an antι-ErbB2 antibody can bind thereto and have a therapeutic effect with respect to the cancer A cancer "characterized by excessive activation" of an ErbB receptor is one in which the extent of ErbB receptor activation in cancer cells significantly exceeds the level of activation of that receptor in non-cancerous cells of the same tissue type Such excessive activation may result from overexpression of the ErbB receptor and/or greater than normal levels of an ErbB hgand available for activating the ErbB receptor in the cancer cells Such excessive activation may cause and/or be caused by the malignant state of a cancer cell In some embodiments, the cancer will be subjected to a diagnostic or prognostic assay to determine whether amplification and/or overexpression of an ErbB receptor is occurring which results in such excessive activation of the ErbB receptor Alternatively, or additionally, the cancer may be subjected to a diagnostic or prognostic assay to determine whether amplification and/or overexpression an ErbB hgand is occurring in the cancer which attributes to excessive activation of the receptor In a subset of such cancers, excessive activation of the receptor may result from an autocπne stimulatory pathway In an "autocπne" stimulatory pathway, self stimulation occurs by virtue of the cancer cell producing both an ErbB hgand and its cognate ErbB receptor For example, the cancer may express or overexpress EGFR and also express or overexpress an EGFR hgand (e g EGF, TGF-α or HB-EGF) In another embodiment, the cancer may express or overexpress ErbB2 and also express or overexpress a heregulin (e g γ-HRG) A cancer which "overexpresses" an ErbB receptor is one which has significantly higher levels of an ErbB receptor, such as ErbB2, at the cell surface thereof, compared to a noncancerous cell of the same tissue type Such overexpression may be caused by gene amplification or by increased transcription or translation ErbB receptor overexpression may be determined in a diagnostic or prognostic assay by evaluating increased levels of the ErbB protein present on the surface of a cell (e g via an immunohistochemistry assay, IHC) Alternatively, or additionally, one may measure levels of ErbB-encoding nucleic acid in the cell, e g via fluorescent in situ hybridization, (FISH, see W098/45479 published October, 1998), southern blotting, or polymerase chain reaction (PCR) techniques, such as real time quantitative PCR (RT-PCR) One may also study ErbB receptor overexpression by measuring shed antigen (e g , ErbB extracellular domain) in a biological fluid such as serum (see, e g , U S Patent No 4,933,294 issued June 12, 1990, W091/05264 published April 18, 1991 , U S Patent 5,401 ,638 issued March 28, 1995, and Sias et al J Immunol Methods 132 73-80 (1990)) Aside from the above assays, various in vivo assays are available to the skilled practitioner For example, one may expose cells within the body of the patient to an antibody which is optionally labeled with a detectable label, e g a radioactive isotope, and binding of the antibody to cells in the patient can be evaluated, e g by external scanning for radioactivity or by analyzing a biopsy taken from a patient previously exposed to the antibody Conversely, a cancer which is "not characterized by overexpression of the ErbB2 receptor" is one which, in a diagnostic assay, does not express higher than normal levels of ErbB 2 receptor compared to a noncancerous cell of the same tissue type A cancer which "overexpresses" an ErbB hgand is one which produces significantly higher levels of that hgand compared to a noncancerous cell of the same tissue type Such overexpression may be caused by gene amplification or by increased transcription or translation Overexpression of the ErbB hgand may be determined diagnostically by evaluating levels of the hgand (or nucleic acid encoding it) in the patient, e g in a tumor biopsy or by various diagnostic assays such as the IHC, FISH, southern blotting, PCR or in vivo assays described above A "hormone-independent" cancer is one in which proliferation thereof is not dependent on the presence of a hormone which binds to a receptor expressed by cells in the cancer Such cancers do not undergo clinical regression upon administration of pharmacological or surgical strategies that reduce the hormone concentration in or near the tumor Examples of hormone-independent cancers include androgen-independent prostate cancer, estrogen-independent breast cancer, endometrial cancer and ovarian cancer. Such cancers may begin as hormone- dependent tumors and progress from a hormone-sensitive stage to a hormone-refractory tumor following anti- hormonal therapy The ter ' cytotoxic agent' as used herein refers to a substance that inhibits or prevents the function of cells 21 1 131 125 90 and/or causes destruction of cells The term is intended to include radioactive isotopes (e g At , 1 , 1 , Y , 186 188 153 212 32 Re , Re , Sm , Bι , P and radioactive isotopes ofLu), chemotherapeutic agents, and toxins such as small molecule toxins or enzymatically active toxins of bacterial, fungal, plant or animal origin, including fragments and/or variants thereof A "chemotherapeutic agent" is a chemical compound useful in the treatment of cancer Examples of chemotherapeutic agents include alkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN™), alkyl sulfonates such as busulfan, improsulfan and piposulfan, aziπdines such as benzodopa, carboquone, meturedopa, and uredopa, ethylenimines and methylamelamines including altretamine, tπethylenemelamine, tπetylenephosphoramide, rπethyienethiophosphaoramide and tπmethylolomelamine, nitrogen mustards such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, lfosfamide, mechlorethamine, mechlorethamine oxide hydrochloπde, melphalan, novembichin, phenesteπne, prednimustine, trofosfamide, uracil mustard, nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine, antibiotics such as aclacinomysins, actmomycin, authramycin, azaseπne, bleomycins, cactinomycin, cahcheamicin, carabicin, carminomycin, carzinophi n, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-dιazo-5-oxo-L-norleucιne, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins, mycophenohc acid, nogalamycin, o vomycins, peplomycm, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigπn, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin, anti-metabolites such as methotrexate and 5-fluorouracιl (5-FU), fohc acid analogues such as denopteπn, methotrexate, pteropteπn, tπmetrexate, puπne analogs such as fludarabine, 6- mercaptopuπne, thiamipπne, thioguanine, pyπmidine analogs such as ancitabine, azacitidine, 6-azauπdιne, carmofur, cytarabine, dideoxyuπdine, doxifluπdine, enocitabine, floxuπdine, 5-FU, androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone, anti-adrenals such as aminoglutethimide, mitotane, tπlostane, fohc acid reple sher such as fro nic acid, aceglatone, aldophosphamide glycoside, aminolevuhnic acid, amsacπne, bestrabucil, bisantrene, edatraxate, defofarmne, demecolcine, diaziquone, elfornithine, elhptinium acetate, etoglucid, gallium nitrate, hydroxyurea, lentinan, lonidamine, mitoguazone, mitoxantrone, mopidamol, nitracπne, pentostatin, phenamet, pirarubicin, podophylhnic acid, 2-ethylhydrazιde, procarbazine, PSK®, razoxane, sizofiran, spirogermanium, tenuazonic acid, tπaziquone, 2, 2', 2"- tπchlorotπethylamine, urethan, vindesine, dacarbazine, mannomustine, mitobronitol, mitolactol, pipobroman, gacytosine, arabinoside ("Ara-C ), cyclophosphamide, thiotepa, taxanes, e g paclitaxel (TAXOL ® , Bristol-Myers Squibb Oncology, Princeton, NJ) and docetaxel (TAXOTERE®, Rhόne-Poulenc Rorer, Antony, France), chlorambucil, gemcitabine, 6-thιoguanιne, mercaptopunne, methotrexate, platinum analogs such as cisplatin and carboplatin, vinblastine, platinum, etoposide (VP-16), lfosfamide, mitomycin C, mitoxantrone, vincπstine, vinorelbine, navelbine, leucovoπn (LV), novantrone, teniposide, daunomycin, aminopteπn, xeloda, ibandronate, CPT-1 1 , topoisomerase inhibitor RFS 2000, difluoromethylornithine (DMFO), retinoic acid, esperamicins, capecitabine, and pharmaceutically acceptable salts, acids or derivatives of any of the above Also included in this definition are anti-hormonal agents that act to regulate or inhibit hormone action on tumors such as anti-estrogens including for example tamoxiten, raloxifene, aromatase inhibiting 4(5)-ιmιdazoles, 4-hydroxytamoxιfen, tπoxifene, keoxifene, LY1 17018, onapπstone, and toremifene (Fareston), and anti-androgens such as flutamide, nilutamide, bicalutamide, leuprohde, and goserehn, and pharmaceutically acceptable salts, acids or derivatives of any of the above The term "cytokine" is a generic term for proteins released by one cell population which act on another cell as intercellular mediators Examples of such cytokines are lymphokines, monokines, and traditional polypeptide hormones Included among the cytokines are growth hormone such as human growth hormone, N-methionyl human growth hormone, and bovine growth hormone, parathyroid hormone, thyroxine, insulin, proinsuhn, relaxin, prorelaxin, glycoprotein hormones such as follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH), hepatic growth factor, fibroblast growth factor, prolactin, placenta! lactogen, tumor necrosis factor-α and -β, mulleπan-inhibiting substance, mouse gonadotropin-associated peptide, inhibin, activin, vascular endothehal growth factor, lntegπn, thrombopoietin (TPO), nerve growth factors such as NGF-β, platelet- growth factor, transforming growth factors (TGFs) such as TGF-α and TGF-β, insulin-like growth factor-I and -II, erythropoietin (EPO), osteoinductive factors, mterferons such as interferon-α, -β, and -γ, colony stimulating factors (CSFs) such as macrophage-CSF (M-CSF), granulocyte-macrophage-CSF (GM-CSF), and granulocyte-CSF (G- CSF), interleukins (ILs) such as IL-1 , IL-l α, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-1 1 , IL-12, a tumor necrosis factor such as TNF-α or TNF-β, and other polypeptide factors including LIF and kit hgand (KL) As used herein, the term cytokine includes proteins from natural sources or from recombinant cell culture and biologically active equivalents of the native sequence cytokines As used herein, the term "EGFR-targeted drug" refers to a therapeutic agent that binds to EGFR receptor and, optionally, inhibits EGFR receptor activation Examples of such agents include antibodies and small molecules that bind to EGFR Examples of antibodies which bind to EGFR include MAb 579 (ATCC CRL HB 8506), MAb 455 (ATCC CRL HB8507), MAb 225 (ATCC CRL 8508), MAb 528 (ATCC CRL 8509) (see, US Patent No 4,943, 533, Mendelsohn et al ) and variants thereof, such as chimeπzed 225 (C225) and reshaped human 225 (H225) (see, WO 96/40210, Imclone Systems Inc ), antibodies that bind type II mutant EGFR (US Patent No 5,212,290), humanized and chimenc antibodies that bind EGFR as described in US Patent No 5,891 ,996, and human antibodies that bind EGFR (see WO98/50433, Abgenix) The anti-EGFR antibody may be conjugated with a cyotoxic agent, thus generating an immunoconjugate (see, e g , EP659,439A2, Merck Patent GmbH) Examples of small molecules that bind to EGFR include ZD1839 (Astra Zeneca), CP-358774 (OSI/Pfizer) and AG1478 An "anti-angiogenic agent" refers to a compound which blocks, or interferes to some degree, the development of blood vessels The anti-angiogenic factor may, for instance, be a small molecule or antibody that binds to a growth factor or growth factor receptor involved in promoting angiogenesis The preferred anti- angiogenic factor herein is an antibody that binds to Vascular Endothe al Growth Factor (VEGF) The term "prodrug" as used in this application refers to a precursor or derivative form of a pharmaceutically active substance that is less cytotoxic to tumor cells compared to the parent drug and is capable of being enzymatically activated or converted into the more active parent form See, e g , Wilman, ' Prodrugs in Cancer Chemotherapy" Biochemical Society Transactions, 14, pp 375-382, 615th Meeting Belfast (1986) and Stella et al , "Prodrugs A Chemical Approach to Targeted Drug Delivery," Directed Drug Delivery, Borchardt et al , (ed ), pp 247-267, Humana Press (1985) The prodrugs of this invention include, but are not limited to, phosphate-containing prodrugs, thiophosphate-containing prodrugs, sultate-containing prodrugs, peptide-containing prodrugs, D-amino acid-modified prodrugs, glycosylated prodrugs, β-lactam-containing prodrugs, optionally substituted phenoxyacetamide-containing prodrugs or optionally substituted phenylacetamide-containing prodrugs, 5-fluorocytosιne and other 5-fluorouπdιne prodrugs which can be converted into the more active cytotoxic free drug Examples of cytotoxic drugs that can be deπvatized into a prodrug form for use in this invention include, but are not limited to, those chemotherapeutic agents described above A "liposome" is a small vesicle composed of various types of hpids, phosphohpids and or surfactant which is useful for delivery of a drug (such as the antι-ErbB2 antibodies disclosed herein and, optionally, a chemotherapeutic agent) to a mammal The components of the liposome are commonly arranged in a bilayer formation, similar to the pid arrangement of biological membranes The term "package insert" is used to refer to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, contraindications and/or warnings concerning the use of such therapeutic products A "cardioprotectant" is a compound or composition which prevents or reduces myocardial dystunction (i e cardiomyopathy and/or congestive heart failure) associated with administration of a drug, such as an anthracychne antibiotic and or an antι-ErbB2 antibody, to a patient The cardioprotectant may, for example, block or reduce a free-radical-mediated cardiotoxic effect and/or prevent or reduce oxidative-stress injury Examples of cardioprotectants encompassed by the present definition include the iron-chelating agent dexrazoxane (ICRF- 187) (Seifert et al The Annals of Pharmacotherapy 28 1063-1072 (1994)), a hpid-loweπng agent and or anti-oxidant such as probucol (Singal et al J Mol Cell Cardiol 27 1055-1063 (1995)), amifostine (aminothiol 2-[(3- amιnopropyl)arrano]ethanethιol-dιhydrogen phosphate ester, also called WR-2721 , and the dephosphorylated cellular uptake form thereof called WR-1065) and 5-3-(3-methylamιnopropylamιno)propylphosphorothιoιc acid (WR-151327), see Green etal Cancer Research 54 738-741 (1994), digoxin (Bπstow, M R In Bπstow MR, ed Drug-Induced Heart Disease New York Elsevier 191-215 (1980)), beta-blockers such as metoprolol (Hjalmarson et al Drugs 47 Suppl 4 31-9 (1994), and Shaddy et al Am Heart J 129 197-9 (1995)), vitamin E, ascorbic acid (vitamin C), free radical scavengers such as oleanohc acid, ursolic acid and N-acetylcysteine (NAC), spin trapping compounds such as alpha-phenyl-tert-butyl nitrone (PBN), (Paracchini etal ,AntιcancerRes 13 1607-1612 (1993)), selenoorganic compounds such as P251 (Elbesen), and the like II. Production of anti-ErbB2 Antibodies A description follows as to exemplary techniques for the production of the antibodies used in accordance with the present invention The ErbB2 antigen to be used for production of antibodies may be, e g , a soluble form of the extracellular domain of ErbB2 or a portion thereof, containing the desired epitope Alternatively, cells expressing ErbB2 at their cell surface (e g NIH-3T3 cells transformed to overexpress ErbB2, or a carcinoma cell line such as SKBR3 cells, see Stancovski et al PNAS (USA) 88 8691-8695 (1991 )) can be used to generate antibodies Other forms of ErbB2 useful for generating antibodies will be apparent to those skilled in the art (i) Polyclonal antibodies Polyclonal antibodies are preferably raised in animals by multiple subcutaneous (sc) or lntrapeπtoneal (φ) injections of the relevant antigen and an adjuvant It may be useful to conjugate the relevant antigen to a protein that is lmmunogenic in the species to be immunized, e g , keyhole limpet hemocyanin, serum albumin, bovine thyroglobu n, or soybean trypsin inhibitor using a bifunctional or den vatizing agent, for example, maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N-hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCl 2 , or R N=C=NR, where R and R are different alkyl groups Animals are immunized against the antigen, lmmunogenic conjugates, or derivatives by combining, e g , 100 μg or 5 μg of the protein or conjugate (for rabbits or mice, respectively) with 3 volumes of Freund s complete adjuvant and injecting the solution intradermally at multiple sites One month later the animals are boosted with 1/5 to 1/10 the original amount of peptide or conjugate in Freund's complete adjuvant by subcutaneous injection at multiple sites Seven to 14 days later the animals are bled and the serum is assayed for antibody titer Animals are boosted until the titer plateaus Preferably, the animal is boosted with the conjugate of the same antigen, but conjugated to a different protein and or through a different cross- nking reagent Conjugates also can be made in recombinant cell culture as protein fusions Also, aggregating agents such as alum are suitably used to enhance the immune response (u) Monoclonal antibodies Monoclonal antibodies are obtained from a population of substantially homogeneous antibodies, i e , the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts Thus, the modifier "monoclonal" indicates the character of the antibody as not being a mixture of discrete antibodies For example, the monoclonal antibodies may be made using the hybπdoma method first described by Kohler etal Nature, 256 495 (1975), or may be made by recombinant DNA methods (U S Patent No 4,816,567) In the hybπdoma method, a mouse or other appropriate host animal, such as a hamster, is immunized as hereinabove described to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the protein used for immunization Alternatively, lymphocytes may be immunized in vitro Lymphocytes then are fused with myeloma cells using a suitable fusing agent, such as polyethylene glycol, to form a hybπdoma cell (Goding, Monoclonal Antibodies Principles and Practice, pp 59-103 (Academic Press, 1986)) The hybπdoma cells thus prepared are seeded and grown in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells For example, if the parental myeloma cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT), the culture medium for the hybridomas typically will include hypoxanthine, aminoptenn, and thymidine (HAT medium), which substances prevent the growth of HGPRT-deficient cells Preferred myeloma cells are those that fuse efficiently, support stable high-level production of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium Among these, preferred myeloma cell lines are muπne myeloma lines, such as those derived from MOPC-21 and MPC-11 mouse tumors a\ ailable from the Salk Institute Cell Distribution Center, San Diego, California USA, and SP-2 or X63-Ag8- 653 cells available from the American Type Culture Collection, Rockville, Maryland USA Human myeloma and mouse-human heteromyeloma cell lines also have been described for the production of human monoclonal antibodies (Kozbor,7 Immunol , 133 3001 (1984), andBrodeure?α/ Monoclonal Antibody Production Techniques and Applications, pp 51-63 (Marcel Dekker, Inc , New York, 1987)) Culture medium in which hybπdoma cells are growing is assayed for production of monoclonal antibodies directed against the antigen Preferably, the binding specificity of monoclonal antibodies produced by hybπdoma cells is determined by lmmunoprecipitation or by an in vitro binding assay, such as radioimmunoassay (RIA) or enzyme-linked immunoabsorbent assay (ELISA) The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson et al Anal Biochem , 107 220 ( 1980) After hybπdoma cells are identified that produce antibodies of the desired specificity, affinity, and/or activity, the clones may be subcloned by limiting dilution procedures and grown by standard methods (Goding, Monoclonal Antibodies Principles and Practice, pp 59-103 (Academic Press, 1986)) Suitable culture media for this purpose include, for example, D-MEM or RPMI- 1640 medium In addition, the hybπdoma cells may be grown in vivo as ascites tumors in an animal The monoclonal antibodies secreted by the subclones are suitably separated from the culture medium, ascites fluid, or serum by conventional antibody purification procedures such as, for example, protein A-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography DNA encoding the monoclonal antibodies is readily isolated and sequenced using conventional procedures {e g , by using ohgonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of muπne antibodies) The hybπdoma cells serve as a preferred source of such DNA Once isolated, the DNA may be placed into expression vectors, which are then transfected into host cells such as E colt cells, simian COS cells, Chinese Hamster Ovary (CHO) cells, or myeloma cells that do not otherwise produce antibody protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells Review articles on recombinant expression in bacteria of DNA encoding the antibody include Skerra et al , Curr Opinion in Immunol , 5 256-262 (1993) and Pluckthun, Immunol Revs , 130 151-188 (1992) In a further embodiment, monoclonal antibodies or antibody fragments can be isolated from antibody phage libraries generated using the techniques described in McCafferty et al , Nature, 348 552-554 (1990) Clackson et al , Nature, 352 624-628 (1991) and Marks et al , J Mol Biol , 222 581-597 (1991) describe the isolation of murine and human antibodies, respectively, using phage libraries Subsequent publications describe the production of high affinity (nM range) human antibodies by chain shuffling (Marks et al , Bio/Technology, 10 779-783 ( 1992)), as well as combinatorial infection and in vivo recombination as a strategy for constructing very large phage libraries (Waterhouse etal , Nuc Acids Res , 21 2265-2266 (1993)) Thus, these techniques are viable alternatives to traditional monoclonal antibody hybπdoma techniques for isolation of monoclonal antibodies The DNA also may be modified, for example, by substituting the coding sequence for human heavy chain and light chain constant domains in place of the homologous murine sequences (U S Patent No 4,816,567, and Morπson, efα/ Proc Natl Acad Sci USA, SI 6851 (1984)), or by covalentlyjoining to the immunoglobulin coding sequence all or part of the coding sequence for a non-immunoglobu n polypeptide Typically such non-immunoglobuhn polypeptides are substituted for the constant domains of an antibody, or they are substituted for the variable domains of one antigen-combining site of an antibody to create a chimenc bivalent antibody comprising one antigen-combining site having specificity for an antigen and another antigen- combining site having specificity for a different antigen (ιιι) Humanized antibodies Methods for humanizing non-human antibodies have been described in the art Preferably, a humanized antibody has one or more amino acid residues introduced into it from a source which is non-human These non- human amino acid residues are often referred to as ' import" residues, which are typically taken from an "import" variable domain Humanization can be essentially performed following the method of Winter and co-workers (Jones et al , Nature, 321 522-525 (1986), Riechmann et al , Nature, 332 323-327 (1988), Verhoeyen et al , Science, 239 1534-1536 (1988)), by substituting hypervanable region sequences for the corresponding sequences of a human antibody Accordingly, such ' humanized" antibodies are chimenc antibodies (U S Patent No 4,816,567) wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species In practice, humanized antibodies are typically human antibodies in which some hypervanable region residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies The choice of human variable domains, both light and heavy, to be used in making the humanized antibodies is very important to reduce antigenicity According to the so-called "best-fit" method, the sequence of the variable domain of a rodent antibody is screened against the entire library of known human variable-domain sequences The human sequence which is closest to that of the rodent is then accepted as the human framework region (FR) for the humanized antibody (Sims et al , J Immunol , 151 2296 ( 1993), Chothia et al , J Mol Biol , 196 901 (1987)) Another method uses a particular framework region derived from the consensus sequence of all human antibodies of a particular subgroup of light or heavy chains The same framework may be used for several different humanized antibodies (Carter etal , Proc Natl Acad Sci USA, 89 4285 (1992), Presta era/ , / Immunol , 151 2623 (1993)) It is further important that antibodies be humanized with retention of high affinity for the antigen and other favorable biological properties To achieve this goal, according to a preferred method, humanized antibodies are prepared by a process of analysis of the parental sequences and various conceptual humanized products using three- dimensional models of the parental and humanized sequences Three-dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences Inspection of these displays permits analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i e , the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen In this way, FR residues can be selected and combined from the recipient and import sequences so that the desired antibody characteristic, such as increased affinity for the target antιgen(s), is achieved In general, the hypervanable region residues are directly and most substantially involved in influencing antigen binding Example 3 below describes production of exemplary humanized antι-ErbB2 antibodies which bind ErbB2 and block hgand activation of an ErbB receptor The humanized antibody of particular interest herein blocks EGF, TGF-α and/or HRG mediated activation of MAPK essentially as effectively as muπne monoclonal antibody 2C4 (or a Fab fragment thereof) and/or binds ErbB2 essentially as effectively as murine monoclonal antibody 2C4 (or a Fab fragment thereof) The humanized antibody herein may, for example, comprise nonhuman hypervanable region residues incorporated into a human variable heavy domain and may further comprise a framework region (FR) substitution at a position selected from the group consisting of 69H, 71H, and 73H, utilizing the variable domain numbering system set forth in Kabat et al , Sequences of Proteins of Immunological Interest, 5th Ed Public Health Service, National Institutes of Health, Bethesda, MD ( 1991 ) In one embodiment, the humanized antibody comprises FR substitutions at two or all of positions 69H, 71 H and 73H An exemplary humanized antibody of interest herein comprises variable heavy domain complementarity determining residues GFTFTDYTMX, where X is preferably D or S (SEQ ID NO 7), DVNPNSGGSIYNQRFKG (SEQ ID NO 8), and/or NLGPSFYFDY (SEQ ID NO 9), optionally comprising amino acid modifications of those CDR residues, e g where the modifications essentially maintain or improve affinity of the antibody For example, the antibody variant of interest may have from about one to about seven or about five amino acid substitutions in the above variable heavy CDR sequences Such antibody variants may be prepared by affinity maturation, e g , as described below The most preferred humanized antibody comprises the variable heavy domain amino acid sequence in SEQ ID NO 4 The humanized antibody may comprise variable light domain complementarity determining residues KASQDVSIGVA (SEQ ID NO 10), SASYX^X 3 , where X 1 is preferably R or L, X 2 is preferably Y or E, and X 3 is preferably T or S (SEQ ID NO 1 1), and QQYYIYPYT (SEQ ID NO 12), e g in addition to those variable heavy domain CDR residues in the preceding paragraph Such humanized antibodies optionally comprise amino acid modifications of the above CDR residues, e g where the modifications essentially maintain or improve affinity of the antibody For example, the antibody variant of interest may have from about one to about seven or about five amino acid substitutions in the above variable light CDR sequences Such antibody variants may be prepared by affinity maturation, e g , as described below The most preferred humanized antibody comprises the variable light domain amino acid sequence in SEQ ID NO 3 The present application also contemplates affinity matured antibodies which antibodies which bind ErbB2 and block ligand activation of an ErbB receptor The parent antibody may be a human antibody or a humanized antibody, e g , one comprising the variable light and/or heavy sequences of SEQ ID Nos 3 and 4, respectively (i e variant 574) The affinity matured antibody preferably binds to ErbB2 receptor with an affinity superior to that of murine 2C4 or variant 574 (e g from about two or about four fold, to about 100 fold or about 1000 fold improved affinity, e g as assessed using a ErbB2-extracellular domain (ECD) ELISA) Exemplary variable heavy CDR residues for substitution include H28, H30, H34, H35, H64, H96, H99, or combinations of two or more (e g two three, four, five, six or seven of these residues) Examples of variable light CDR residues for alteration include L28, L50, L53, L56, L91 , L92, L93, L94, L96, L97 or combinations of two or more (e g two to three, four, five or up to about ten of these residues) Various forms of the humanized or affinity matured antibody are contemplated For example, the humanized or affinity matured antibody may be an antibody fragment, such as a Fab, which is optionally conjugated with one or more cytotoxic agent(s) in order to generate an immunoconjugate Alternatively, the humanized or affinity matured antibody may be an intact antibody, such as an intact IgGl antibody (iv) Human antibodies As an alternative to humanization, human antibodies can be generated For example, it is now possible to produce transgenic animals (e g , mice) that are capable, upon immunization, of producing a full repertoire of human antibodies in the absence of endogenous immunoglobulin production For example, it has been described that the homozygous deletion of the antibody heavy-chain joining region (J H ) gene in chimenc and germ-line mutant mice results in complete inhibition of endogenous antibody production Transfer of the human germ-line immunoglobulin gene aπay in such germ-line mutant mice will result in the production of human antibodies upon antigen challenge See, e g , Jakobovits et al , Proc Natl Acad Sci USA, 90 2551 (1993), Jakobovits et al , Nature, 362 255-258 (1993), Bruggermann et al , Year in Immuno , 7 33 (1993), and U S Patent Nos 5,591 ,669, 5,589,369 and 5,545,807 Alternatively, phage display technology (McCafferty et al , Nature 348 552-553 ( 1990)) can be used to produce human antibodies and antibody fragments in vitro, from immunoglobulin variable (V) domain gene repertoires from unimmu zed donors According to this technique, antibody V domain genes are cloned in-frame into either a major or minor coat protein gene of a filamentous bacteπophage, such as M 13 or fd, and displayed as functional antibody fragments on the surface of the phage particle Because the filamentous particle contains a single-stranded DNA copy of the phage genome, selections based on the functional properties of the antibody also result in selection of the gene encoding the antibody exhibiting those properties Thus, the phage mimics some of the properties of the B-cell Phage display can be performed in a variety of formats, for their review see, e g , Johnson, Kevin S and Chiswell, David J , Current Opinion in Structural Biology 3 564-571 (1993) Several sources of V-gene segments can be used for phage display Clackson et al , Nature, 352 624-628 ( 1991 ) isolated a diverse array of anti-oxazolone antibodies from a small random combinatorial library of V genes derived from the spleens of immunized mice A repertoire of V genes from unimmunized human donors can be constructed and antibodies to a diverse array of antigens (including self-antigens) can be isolated essentially following the techniques described by Marks et al , J Mol Biol 222 581-597 (1991 ), or Griffith et al , EMBO J 12 725-734 (1993) See, also, U S Patent Nos 5,565,332 and 5,573,905 As discussed above, human antibodies may also be generated by in vitro activated B cells (see U S Patents 5,567,610 and 5,229,275) Human antι-ErbB2 antibodies are described in U S Patent No 5,772,997 issued June 30, 1998 and WO 97/00271 published January 3, 1997 (v) Antibody fragments Various techniques have been developed for the production of antibody fragments Traditionally, these fragments were derived via proteolytic digestion of intact antibodies (see, e g , Monmoto et al , Journal of Biochemical and Biophysical Methods 24 107-1 17 (1992), and Brennan etal , Science, 229 81 (1985)) However, these fragments can now be produced directly by recombinant host cells For example, the antibody fragments can be isolated from the antibody phage libraries discussed above Alternatively, Fab'-SH fragments can be directly recovered from E coh and chemically coupled to form F(ab') 2 fragments (Carter etal , Bio/Technology 10 163- 167 ( 1992)) According to another approach, F(ab fragments can be isolated directly from recombinant host cell culture Other techniques for the production of antibody fragments will be apparent to the skilled practitioner In other embodiments, the antibody of choice is a single chain Fv fragment (scFv) See WO 93/16185, U S Patent No 5,571 ,894, and U S Patent No 5,587,458 The antibody fragment may also be a "linear antibody", e g , as described in U S Patent 5,641 ,870 for example Such linear antibody fragments may be monospecific or bispecific (vή Bispecific antibodies Bispecific antibodies are antibodies that have binding specificities for at least two different epitopes Exemplary bispecific antibodies may bind to two different epitopes of the ErbB2 protein Other such antibodies may combine an ErbB2 binding site with binding sιte(s) for EGFR, ErbB3 and/or ErbB4 Alternatively, an anti- ErbB2 arm may be combined with an arm which binds to a triggering molecule on a leukocyte such as a T-cell receptor molecule (e g CD2 or CD3), or Fc receptors for IgG (FcγR), such as FcγRI (CD64), FcγRII (CD32) and FcγRIII (CD 16) so as to focus cellular defense mechanisms to the ErbB2-expressιng cell Bispecific antibodies may also be used to localize cytotoxic agents to cells which express ErbB2 These antibodies possess an ErbB2- binding arm and an arm which binds the cytotoxic agent (e g sapoπn, anti-interferon-α, vinca alkaloid, πcin A chain, methotrexate or radioactive isotope hapten) Bispecific antibodies can be prepared as full length antibodies or antibody fragments (e g F(ab') 2 bispecific antibodies) WO 96/16673 describes a bispecific antι-ErbB2/antι-FcγRIII antibody and U S Patent No 5,837,234 discloses a bispecific antι-ErbB2/antι -FcγRI antibody A bispecific antι-ErbB2/Fcα antibody is shown in WO98/02463 U S Patent No 5,821,337 teaches a bispecific antι-ErbB2/antι-CD3 antibody Methods for making bispecific antibodies are known in the art Traditional production of full length bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two chains have different specificities (Millstein et al , Nature, 305 537-539 (1983)) Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure Purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low Similar procedures are disclosed in WO 93/08829, and in Traunecker et al , EMBO 7 , 10 3655-3659 (1991) According to a different approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions It is preferred to have the first heavy-chain constant region (CHI) containing the site necessary for light chain binding, present in at least one of the fusions DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain- light chain pair (providing a second binding specificity) in the other arm It was found that this asymmetric structure facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglobulin light chain in only one half of the bispecific molecule provides for a facile way of separation This approach is disclosed in WO 94/04690 For further details of generating bispecific antibodies see, for example, Suresh et al , Methods in Enzymology, 121 210 (1986) According to another approach described in U S Patent No 5,731 ,168, the interface between a pair of antibody molecules can be engineered to maximize the percentage of heterodimers which are recovered from recombinant cell culture The preferred interface comprises at least a part of the C H 3 domain of an antibody constant domain In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e g tyrosine or tryptophan) Compensatory "cavities" of identical or similar size to the large side chaιn(s) are created on the interface of the second antibody molecule by replacing large am o acid side chains with smaller ones (e g alanine or threonine) This provides a mechanism for increasing the yield of the heterodimer over other unwanted end-products such as homodimers Bispecific antibodies include cross-linked or "heteroconjugate' antibodies For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U S Patent No 4,676,980), and for treatment of HIV infection (WO 91/00360, WO 92/200373, and EP 03089) Heteroconjugate antibodies may be made using any convenient cross-linking methods Suitable cross-linking agents are well known in the art, and are disclosed in U S Patent No 4,676,980, along with a number of cross-linking techniques Techniques for generating bispecific antibodies from antibody fragments have also been described in the literature For example, bispecific antibodies can be prepared using chemical linkage Brennan et al , Science, 229 81 (1985) describe a procedure wherein intact antibodies are proteolytically cleaved to generate F(ab)2 fragments These fragments are reduced in the presence of the dithiol complexing agent sodium arsenite to stabilize vicinal dithiols and prevent mtermolecular disulfide formation The Fab' fragments generated are then converted to thionitrobenzoate (TNB) derivatives One of the Fab -TNB derivatives is then reconverted to the Fab -thiol by reduction with mercaptoethylamine and is mixed with an equimolar amount of the other Fab'-TNB derivative to form the bispecific antibody The bispecific antibodies produced can be used as agents for the selective immobilization of enzymes Recent progress has facilitated the direct recovery of Fab -SH fragments from E colt which can be chemically coupled to form bispecific antibodies Shalaby et al , J Exp Med , 175 217-225 (1992) describe the production of a fully humanized bispecific antibody F(ab 2 molecule Each Fab' fragment was separately secreted from E coh and subjected to directed chemical coupling in vitro to form the bispecific antibody The bispecific antibody thus formed was able to bind to cells overexpressing the ErbB2 receptor and normal human T cells, as well as trigger the lytic activity of human cytotoxic lymphocytes against human breast tumor targets Various techniques for making and isolating bispecific antibody fragments directly from recombinant cell culture have also been described For example, bispecific antibodies have been produced using leucine zippers Kostelny et al , J Immunol , 148(5) 1547-1553 (1992) The leucine zipper peptides from the Fos and Jun proteins were linked to the Fab' portions of two different antibodies by gene fusion The antibody homodimers were reduced at the hinge region to form monomers and then re-oxidized to form the antibody heterodimers This method can also be utilized for the production of antibody homodimers The diabody" technology described by Hollinger et al , Proc Natl Acad Set USA, 90 6444-6448 (1993) has provided an alternative mechanism for making bispecific antibody fragments The fragments comprise a heavy-chain variable domain (V H ) connected to a light- chain variable domain (V L ) by a linker which is too short to allow pairing between the two domains on the same chain Accordingly, the V H and V L domains of one fragment are forced to pair with the complementary V and V H domains of another fragment, thereby forming two antigen-binding sites Another strategy for making bispecific antibody fragments by the use of single-chain Fv (sFv) dimers has also been reported See Gruber et al , J Immunol , 152 5368 (1994) Antibodies with more than two valencies are contemplated For example, tπspecific antibodies can be prepared Υ U et al J Immunol 147 60 (1991 ) (vn) Other amino acid sequence modifications Amino acid sequence modιfιcatιon(s) of the antι-ErbB2 antibodies described herein are contemplated For example, it may be desirable to improve the binding affinity and or other biological properties of the antibody Amino acid sequence variants of the antι-ErbB2 antibody are prepared by introducing appropriate nucleotide changes into the antι-ErbB2 antibody nucleic acid, or by peptide synthesis Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of, residues within the amino acid sequences of the antι-ErbB2 antibody Any combination of deletion, insertion, and substitution is made to arrive at the final construct, provided that the final construct possesses the desired characteristics The amino acid changes also may alter post-translational processes of the antι-ErbB2 antibody, such as changing the number or position of glycosylation sites A useful method for identification of certain residues or regions of the antι-ErbB2 antibody that are preferred locations for mutagenesis is called "alanine scanning mutagenesis" as described by Cunningham and Wells Science, 244 1081-1085 (1989) Here, a residue or group of target residues are identified (e g , charged residues such as arg, asp, his, lys, and glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine) to affect the interaction of the amino acids with ErbB 2 antigen Those amino acid locations demonstrating functional sensitivity to the substitutions then are refined by introducing further or other variants at, or for, the sites of substitution Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined For example, to analyze the performance of a mutation at a given site, ala scanning or random mutagenesis is conducted at the target codon or region and the expressed antι-ErbB2 antibody variants are screened for the desired activity Amino acid sequence insertions include amino- and/or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues Examples of terminal insertions include an antι-ErbB2 antibody with an N-terminal methionyl residue or the antibody fused to a cytotoxic polypeptide Other insertional variants of the antι-ErbB2 antibody molecule include the fusion to the N- or C-terminus of the antι-ErbB2 antibody to an enzyme (e g for ADEPT) or a polypeptide which increases the serum half-life of the antibody Another type of variant is an amino acid substitution variant These variants have at least one amino acid residue in the antι-ErbB2 antibody molecule replaced by a different residue The sites of greatest interest for substitutional mutagenesis include the hypervanable regions, but FR alterations are also contemplated Conservative substitutions are shown in Table 1 under the heading of "preferred substitutions" If such substitutions result in a change in biological activity, then more substantial changes, denominated ' exemplary substitutions" in Table 1 , or as further described below in reference to amino acid classes, may be introduced and the products screened Table 1 Substantial modifications in the biological properties of the antibody are accomplished by selecting substitutions that differ significantly in their effect on maintaining (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a sheet or helical conformation, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chain Naturally occurring residues are divided into groups based on common side-chain properties (1 ) hydrophobic norleucine, met, ala, val, leu, lie, (2) neutral hydrophilic cys, ser, thr, (3) acidic asp, glu, (4) basic asn, gin, his, lys, arg, (5) residues that influence chain orientation gly, pro, and (6) aromatic trp, tyr, phe Non-conservative substitutions will entail exchanging a member of one of these classes for another class Any cysteine residue not involved in maintaining the proper conformation of the antι-ErbB2 antibody also may be substituted, generally with seπne, to improve the oxidative stability of the molecule and prevent aberrant crosshnking Conversely, cysteine bond(s) may be added to the antibody to improve its stability (particularly where the antibody is an antibody fragment such as an Fv fragment) A particularly preferred type of substitutional variant involves substituting one or more hypervanable region residues of a parent antibody (e g a humanized or human antibody) Generally, the resulting vaπant(s) selected for further development will have improved biological properties relative to the parent antibody from which they are generated A convenient way for generating such substitutional variants involves affinity maturation using phage display Briefly, several hypervanable region sites (e g 6-7 sites) are mutated to generate all possible amino substitutions at each site The antibody variants thus generated are displayed in a monovalent fashion from filamentous phage particles as fusions to the gene III product of M 13 packaged within each particle The phage - displayed variants are then screened for their biological activity (e g binding affinity) as herein disclosed In order to identify candidate hypervanable region sites for modification, alanine scanning mutagenesis can be performed to identify hypervanable region residues contributing significantly to antigen binding Alternatively, or additionally, it may be beneficial to analyze a crystal structure of the antigen-antibody complex to identify contact points between the antibody and human ErbB2 Such contact residues and neighboring residues are candidates for substitution according to the techniques elaborated herein Once such variants are generated, the panel of variants is subjected to screening as described herein and antibodies with superior properties in one or more relevant assays may be selected for further development Another type of amino acid variant of the antibody alters the original glycosylation pattern of the antibody By altering is meant deleting one or more carbohydrate moieties found in the antibody, and/or adding one or more glycosylation sites that are not present in the antibody Glycosylation of antibodies is typically either N-hnked or O-hnked N-hnked refers to the attachment of the carbohydrate moiety to the side chain of an asparagine residue The tπpeptide sequences asparagine-X-seπne and asparagine-X-threonine, where X is any amino acid except prohne, are the recognition sequences for enzymatic attachment of the carbohydrate moiety to the asparagine side chain Thus, the presence of either of these tπpeptide sequences in a polypeptide creates a potential glycosylation site O-hnked glycosylation refers to the attachment of one of the sugars N-aceylgalactosamine, galactose, or xylose to a hydroxyamino acid, most commonly seπne or threonine, although 5-hydroxyprohne or 5-hydroxylysιne may also be used Addition of glycosylation sites to the antibody is conveniently accomplished by altering the amino acid sequence such that it contains one or more of the above-described tπpeptide sequences (for N-hnked glycosylation sites) The alteration may also be made by the addition of, or substitution by, one or more seπne or threonine residues to the sequence of the original antibody (for O-hnked glycosylation sites) Nucleic acid molecules encoding amino acid sequence variants of the antι-ErbB2 antibody are prepared by a variety of methods known in the art These methods include, but are not limited to, isolation from a natural source (in the case of naturally occurring amino acid sequence variants) or preparation by ohgonucleotide-mediated (or site-directed) mutagenesis, PCR mutagenesis, and cassette mutagenesis of an earlier prepared variant or a non- variant version of the antι-ErbB2 antibody It may be desirable to modify the antibody of the invention with respect to effector function, e g so as to enhance antigen-dependent cell-mediated cyotoxicity (ADCC) and or complement dependent cytotoxicity (CDC) of the antibody This may be achieved by introducing one or more amino acid substitutions in an Fc region of the antibody Alternatively or additionally, cysteine resιdue(s) may be introduced in the Fc region, thereby allowing interchain disulfide bond formation in this region The homodimeπc antibody thus generated may have improved lnternahzation capability and/or increased complement-mediated cell killing and antibody-dependent cellular cytotoxicity (ADCC) See Caron et al , J Exp Med 176 1 191 -1 195 (1992) and Shopes, B J Immunol 148 2918- 2922 (1992) Homodimeπc antibodies with enhanced anti-tumor activity may also be prepared using heterobifunctional cross-linkers as described in Wolff etal Cancer Research 53 2560-2565 ( 1993) Alternatively, an antibody can be engineered which has dual Fc regions and may thereby have enhanced complement lysis and ADCC capabilities See Stevenson et al Anti-Cancer Drug Design 3 219-230 (1989) To increase the serum half life of the antibody, one may incorporate a salvage receptor binding epitope into the antibody (especially an antibody fragment) as described in U S Patent 5,739,277, for example As used herein, the term "salvage receptor binding epitope" refers to an epitope of the Fc region of an IgG molecule (e g , IgG j , IgG 2 , IgG 3 , or IgG 4 ) that is responsible for increasing the in vivo serum half-life of the IgG molecule (viu) Screening for antibodies with the desired properties Techniques for generating antibodies have been described above One may further select antibodies with certain biological characteristics, as desired To identify an antibody which blocks ligand activation of an ErbB receptor, the ability of the antibody to block ErbB hgand binding to cells expressing the ErbB receptor (e g in conj ugation with another ErbB receptor with which the ErbB receptor of interest forms an ErbB hetero-ohgomer) may be determined For example, cells naturally expressing, or transfected to express, ErbB receptors of the ErbB hetero-ohgomer may be incubated with the antibody and then exposed to labeled ErbB ligand The ability of the antι-ErbB2 antibody to block ligand binding to the ErbB receptor in the ErbB hetero-ohgomer may then be evaluated For example, inhibition of HRG binding to MCF7 breast tumor cell lines by antι-ErbB2 antibodies may be performed using monolayer MCF7 cultures on ice in a 24-well-plate format essentially as described in Example 125 1 below Antι-ErbB2 monoclonal antibodies may be added to each well and incubated for 30 minutes I-labeled rHRGβl 177 224 (25 pm) may then be added, and the incubation may be continued for 4 to 16 hours Dose response curves may be prepared and an IC 50 value may be calculated for the antibody of interest In one embodiment, the antibody which blocks ligand activation of an ErbB receptor will have an IC 50 for inhibiting HRG binding to MCF7 cells in this assay of about 50nM or less, more preferably lOnM or less Where the antibody is an antibody fragment such as a Fab fragment, the IC 50 for inhibiting HRG binding to MCF7 cells in this assay may, for example, be about 1 OOnM or less, more preferably 50nM or less Alternatively, or additionally, the ability of the antι-ErbB2 antibody to block ErbB hgand-stimulated tyrosine phosphorylation of an ErbB receptor present in an ErbB hetero-ohgomer may be assessed For example cells endogenously expressing the ErbB receptors or transfected to expressed them may be incubated with the antibody and then assayed for ErbB hgand-dependent tyrosine phosphorylation activity using an anti- phosphotyrosine monoclonal (which is optionally conjugated with a detectable label) The kinase receptor activation assay described in U S Patent No 5,766,863 is also available for determining ErbB receptor activation and blocking of that activity by an antibody In one embodiment, one may screen for an antibody which inhibits HRG stimulation of pi 80 tyrosine phosphorylation in MCF7 cells essentially as described in Example 1 below For example, the MCF7 cells may be plated in 24-well plates and monoclonal antibodies to ErbB2 may be added to each well and incubated lor 30 minutes at room temperature, then rHRGβl 177 2 may be added to each well to a final concentration of 0 2 nM and the incubation may be continued for 8 minutes Media may be aspirated from each well, and reactions may be stopped by the addition of 100 μl of SDS sample buffer (5% SDS, 25 mM DTT, and 25 mM Tπs-HCl, pH 6 8) Each sample (25 μl) may be electrophoresed on a 4-12% gradient gel (Novex) and then electrophoretically transferred to polyviny dene difluoπde membrane Antiphosphotyrosine (at 1 μg/ml) immunoblots may be developed, and the intensity of the predominant reactive band at M r - 180,000 may be quantified by reflectance densitometry The antibody selected will preferably significantly inhibit stimulation of pi 80 tyrosime phosphorylation to about 0-35% of control in this assay A dose-response curve for inhibition of HRG stimulation of pi 80 tyrosine phosphorylation as determined by reflectance densitometry may be prepared and an IC 50 for the antibody of interest may be calculated In one embodiment, the antibody which blocks ligand activation of an ErbB receptor will have an IC 50 for inhibiting HRG stimulation of pi 80 tyrosine phosphorylation in this assay of about 50nM or less, more preferably lOnM or less Where the antibody is an antibody fragment such as a Fab fragment, the IC 50 for inhibiting HRG stimulation of pi 80 tyrosine phosphorylation in this assay may, for example, be about lOOnM or less, more preferably 50nM or less One may also assess the growth inhibitory effects of the antibody on MDA-MB-175 cells, e g, essentially as described in Schaefer et al Oncogene 15 1385-1394 (1997) According to this assay, MDA-MB-175 cells may treated with an antι-ErbB2 monoclonal antibody (lOμg/mL) for 4 days and stained with crystal violet Incubation with an antι-ErbB2 antibody may show a growth inhibitory effect on this cell line similar to that displayed by monoclonal antibody 2C4 In a further embodiment, exogenous HRG will not significantly reverse this inhibition Preferably, the antibody will be able to inhibit cell proliferation of MDA-MB-175 cells to a greater extent than monoclonal antibody 4D5 (and optionally to a greater extent than monoclonal antibody 7F3), both in the presence and absence of exogenous HRG In one embodiment, the antι-ErbB2 antibody of interest may block heregulin dependent association of ErbB2 with ErbB3 in both MCF7 and SK-BR-3 cells as determined in a co-immunoprecipitation experiment such as that described in Example 2 substantially more effectively than monoclonal antibody 4D5 and, optionally, substantially more effectively than monoclonal antibody 7F3 Alternatively, or additionally, one may determine the ability of the antibody to block EGF, TGF-α and/or HRG mediated activation of mitogen-activated protein kinase (MAPK), e g , as shown in Example 4 below An antibody which blocks EGF, TGF-α and/or HRG mediated activation of mitogen-activated protein kinase (MAPK) to a greater extent than HERCEPTIN® or monoclonal antibody 4D5 may be selected Moreover, the antibody of interest may block EGF, TGF-α and/or HRG mediated activation of mitogen-activated protein kinase (MAPK) to a greater extent than monoclonal antibody 7F3 To identify growth inhibitory antι-ErbB2 antibodies, one may screen for antibodies which inhibit the growth of cancer cells which overexpress ErbB2 In one embodiment, the growth inhibitory antibody of choice is able to inhibit growth of SK-BR-3 cells in cell culture by about 20-100% and preferably by about 50-100% at an antibody concentration of about 0 5 to 30 μg/ml To identify such antibodies, the SK-BR-3 assay described in U S Patent No 5,677,171 can be performed According to this assay, SK-BR-3 cells are grown in a 1 1 mixture of F12 and DMEM medium supplemented with 10% fetal bovine serum, glutamine and penicillin streptomycin The SK- BR-3 cells are plated at 20,000 cells in a 35mm cell culture dish (2mls/35mm dish) 0 5 to 30 μg/ml of the anti- ErbB2 antibody is added per dish After six days, the number of cells, compared to untreated cells are counted using an electronic COULTER™ cell counter Those antibodies which inhibit growth of the SK-BR-3 cells by about 20-100% or about 50-100% may be selected as growth inhibitory antibodies To select for antibodies which induce cell death, loss of membrane integrity as indicated by, e g , PI, trypan blue or 7AAD uptake may be assessed relative to control The preferred assay is the PI uptake assay using BT474 cells According to this assay, BT474 cells (which can be obtained from the American Type Culture Collection (Rockville, MD)) are cultured in Dulbecco's Modified Eagle Medium (D-MEM) Ham's F-12 (50 50) supplemented with 10% heat-inactivated FBS (Hyclone) and 2 mM L-glutamine (Thus, the assay is performed in the absence of complement and immune effector cells) The BT474 cells are seeded at a density of 3 x 10 per dish in 100 x 20 mm dishes and allowed to attach overnight The medium is then removed and replaced with fresh medium alone or medium containing lOμg/ml of the appropriate monoclonal antibody The cells are incubated for a 3 day time period Following each treatment, monolayers are washed with PBS and detached by trypsinization Cells are then centπfuged at 1200rpm for 5 minutes at 4"C, the pellet resuspended in 3 ml ice cold Ca binding buffer (10 mM Hepes, pH 7 4, 140 mM NaCl, 2 5 mM CaCl 2 ) and a quoted into 35 mm strainer-capped 12 x 75 tubes (1ml per tube, 3 tubes per treatment group) for removal of cell clumps Tubes then receive PI (lOμg/ml) Samples may be analyzed using a FACSCAN™ flow cytometer and FACSCONVERT™ CellQuest software (Becton Dickinson) Those antibodies which induce statistically significant levels of cell death as determined by PI uptake may be selected as cell death-inducing antibodies In order to select for antibodies which induce apoptosis, an annexin binding assay using BT474 cells is available The BT474 cells are cultured and seeded in dishes as discussed in the preceding paragraph The medium is then removed and replaced with fresh medium alone or medium containing 1 Oμg ml of the monoclonal antibody Following a three day incubation period, monolayers are washed with PBS and detached by trypsinization Cells are then centrifuged, resuspended in Ca binding buffer and ahquoted into tubes as discussed above for the cell death assay Tubes then receive labeled annexin (e g annexin V-FTIC) ( 1 μg/ml) Samples may be analyzed using a FACSCAN™ flow cytometer and FACSCONVERT™ CellQuest software (Becton Dickinson) Those antibodies which induce statistically significant levels of annexin binding relative to control are selected as apoptosis-inducing antibodies In addition to the annexin binding assay, a DNA staining assay using BT474 cells is available In order to perform this assay, BT474 cells which have been treated with the antibody of interest as described in the preceding two paragraphs are incubated with 9μg/ml HOECHST 33342™ for 2 hr at 37°C, then analyzed on an EPICS ELITE™ flow cytometer (Coulter Corporation) using MODFIT LT™ software (Verity Software House) Antibodies which induce a change in the percentage of apoptotic cells which is 2 fold or greater (and preferably 3 fold or greater) than untreated cells (up to 100% apoptotic cells) may be selected as pro-apoptotic antibodies using this assay To screen for antibodies which bind to an epitope on ErbB2 bound by an antibody of interest, a routine cross-blocking assay such as that described in Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane ( 1988), can be performed Alternatively, or additionally, epitope mapping can be performed by methods known in the art (see, e g Figs 1 A and IB herein) (ιx) Immunoconjugates The invention also pertains to therapy with immunoconjugates comprising an antibody conjugated to a cytotoxic agent such as a chemotherapeutic agent, toxin (e g a small molecule toxin or an enzymatically active toxin of bacterial, fungal, plant or animal origin, including fragments and/or variants thereof), or a radioactive isotope (i e , a radioconjugate) Chemotherapeutic agents useful in the generation of such immunoconjugates have been described above Conjugates of an antibody and one or more small molecule toxins, such as a caliche amicin, a maytansine (U S Patent No 5,208,020), a tπchothene, and CC1065 are also contemplated herein In one preferred embodiment of the invention, the antibody is conjugated to one or more maytansine molecules (e g about 1 to about 10 maytansine molecules per antibody molecule) Maytansine may, for example, be converted to May-SS-Me which may be reduced to May-SH3 and reacted with modified antibody (Chan et al Cancer Research 52 127-131 (1992)) to generate a maytansinoid-antibody immunoconjugate Another immunoconjugate of interest comprises an antι-ErbB2 antibody conjugated to one or more calicheamicin molecules The cahcheamicin family of antibiotics are capable of producing double-stranded DNA breaks at sub-picomolar concentrations Structural analogues of calicheamicin which may be used include, but are not limited to, y i , α 2 , α 3 , N-acetyl-γ [ , PSAG and θ , ( mman et al Cancer Research 53 3336-3342 (1993) and Lode et al Cancer Research 58 2925-2928 (1998)) Enzymatically active toxins and fragments thereof which can be used include diphtheria A chain, nonbinding active fragments of diphtheria toxin, exotoxin A chain (from Pseudomonas aeruginosa), πcin A chain, abπn A chain, modeccin A chain, alpha-sarcin, Aleuntes fordu proteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII, and PAP-S), momordica charantia inhibitor, curcin, crotin, sapaonaπa off lcinahs inhibitor, gelonin, mitogelhn, restnctocin, phenomycin, enomycin and the tricothecenes See, for example, WO 93/21232 published October 28, 1993 The present invention further contemplates an immunoconjugate formed between an antibody and a compound with nucleolytic activity (e g a πbonuclease or a DNA endonuclease such as a deoxyπbonuclease, DNase) A variety of radioactive isotopes are available for the production of radioconjugated antι-ErbB2 antibodies c Examp iles incl _ud Ae A Λ .t 2 1 1 , τ1 1 3 1 , τ1 1 25 , v Y 90 , r R>e 1 86 , n Re 1 88 , S cm 1 53 , r B>i 2 I 2 , r P> 32 and A rad Aioactive iso .topes o f f ι Lu Conjugates of the antibody and cytotoxic agent may be made using a variety of bifunctional protein coupling agents such as N-succιnιmιdyl-3-(2-pyπdyldιthιol) propionate (SPDP), succιnιmιdyl-4-(N- maleimidomethyl) cyclohexane-1-carboxylate, lminothiolane (IT), bifunctional derivatives of lmidoesters (such as dimethyl adipimidate HCL), active esters (such as disuccinimidyl suberate), aldehydes (such as glutareldehyde), bis- azido compounds (such as bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (such as bιs-(p- diazoniumbenzoy -ethylenediamine), dnsocyanates (such as tolyene 2,6-dnsocyanate), and bis-active fluorine compounds (such as l ,5-dιfluoro-2,4-dιnιtrobenzene) For example, a πcin lmmunotoxin can be prepared as described in Vitettaefα/ Scιe«ce238 1098 (1987) Carbon- 14-labeled l-ιsothιocyanatobenzyl-3-methyldιethylene tπaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent for conjugation of radionucleotide to the antibody See W094/11026 The linker may be a "cleavable linker" facilitating release of the cytotoxic drug in the cell For example, an acid-labile linker, peptidase-sensitive linker, dimethyl linker or disulfide-containing linker (Chan et al Cancer Research 52 127-131 (1992)) may be used Alternatively, a fusion protein comprising the antι-ErbB2 antibody and cytotoxic agent may be made, e g by recombinant techniques or peptide synthesis In yet another embodiment, the antibody may be conjugated to a "receptor" (such streptavidin) for utilization in tumor pretargeting wherein the antibody-receptor conjugate is administered to the patient, followed by removal of unbound conjugate from the circulation using a clearing agent and then administration of a ' hgand" (e g avidin) which is conjugated to a cytotoxic agent (e g a radionucleotide) (x) Antibody Dependent Enzyme Mediated Prodrug Therapy (ADEPT) The antibodies of the present invention may also be used in ADEPT by conjugating the antibody to a prodrug-activating enzyme which converts a prodrug (e g a peptidyl chemotherapeutic agent, see W081/01 145) to an active anti-cancer drug See, for example, WO 88/07378 and U S Patent No 4,975,278 The enzyme component of the immunoconjugate useful for ADEPT includes any enzyme capable of acting on a prodrug in such a way so as to covert it into its more active, cytotoxic form Enzymes that are useful in the method of this invention include, but are not limited to, alkaline phosphatase useful for converting phosphate-containing prodrugs into free drugs, arylsulfatase useful for converting sulfate- containing prodrugs into free drugs, cytosine deaminase useful for converting non-toxic 5-fluorocytosιne into the anti-cancer drug, 5-fluorouracil, proteases, such as serratia protease, thermolysin, subtihsin, carboxypeptidases and cathepsins (such as cathepsins B and L), that are useful for converting peptide-containing prodrugs into free drugs, D-alanylcarboxypeptidases, useful for converting prodrugs that contain D-amino acid substituents, carbohydrate- cleaving enzymes such as β-galactosidase and neuraminidase useful for converting glycosylated prodrugs into free drugs, β-lactamase useful for converting drugs deπvatized with β-lactams into free drugs, and penicillin amidases, such as penicillin V amidase or penicillin G amidase, useful for converting drugs deπvatized at their amine nitrogens with phenoxyacetyl or phenylacetyl groups, respectively, into free drugs Alternatively, antibodies with enzymatic activity, also known in the art as "abzymes", can be used to convert the prodrugs of the invention into free active drugs (see, e g , Massey, Nature 328 457-458 (1987)) Antibody-abzyme conjugates can be prepared as described herein for delivery of the abzyme to a tumor cell population The enzymes of this invention can be covalently bound to the antι-ErbB2 antibodies by techniques well known in the art such as the use of the heterobifunctional crosshnking reagents discussed above Alternatively, fusion proteins comprising at least the antigen binding region of an antibody of the invention linked to at least a functionally active portion of an enzyme of the invention can be constructed using recombinant DNA techniques well known in the art (see, e g , Neuberger et al , Nature, 312 604-608 ( 1984) (xι) Other antibody modifications Other modifications of the antibody are contemplated herein For example, the antibody may be linked to one of a variety of nonproteinaceous polymers, e g , polyethylene glycol, polypropylene glycol, polyoxyalkylenes, or copolymers of polyethylene glycol and polypropylene glycol The antibody also may be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization (for example, hydroxymethylcellulose or gelatin-microcapsules and poly-(methylmethacylate) microcapsules, respectively), in colloidal drug delivery systems (for example, hposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules), or in macroemulsions Such techniques are disclosed in Remington 's Pharmaceutical Sciences, 16th edition, Oslo, A , Ed , (1980) The antι-ErbB2 antibodies disclosed herein may also be formulated as immunoliposomes Liposomes containing the antibody are prepared by methods known in the art, such as described in Epstein et al , Proc Natl Acad Set f/& , 82 3688 (1985), Hwang et al , Proc Natl Acad Set USA, 11 4030 (1980), U S Pat Nos 4,485,045 and 4,544,545 , and W097/38731 published October 23 , 1997 Liposomes with enhanced circulation time are disclosed in U S Patent No 5,013,556 Particularly useful liposomes can be generated by the reverse phase evaporation method with a pid composition comprising phosphatidylcho ne, cholesterol and PEG-deπvatized phosphatidylethanolamine (PEG- PE) Liposomes are extruded through filters of defined pore size to yield liposomes with the desired diameter Fab' fragments of the antibody of the present invention can be conjugated to the hposomes as described in Martin et al J Biol Chem 257 286-288 (1982) via a disulfide interchange reaction A chemotherapeutic agent is optionally contained within the liposome See Gabizon et al J National Cancer Inst 81 (19)1484 (1989) III. Pharmaceutical Formulations Therapeutic formulations of the antibodies used in accordance with the present invention are prepared for storage by mixing an antibody having the desired degree of purity with optional pharmaceutically acceptable carriers, excipients or stabilizers (Remington 's Pharmaceutical Sciences 16th edition, Osol, A Ed (1980)), in the form of lyophihzed formulations or aqueous solutions Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids, antioxidants including ascorbic acid and methionine, preservatives (such as octadecyldimethylbenzyl ammonium chloride, hexamethonium chloride, benzalkonium chloride, benzethonium chloride, phenol, butyl or benzyl alcohol, alkyl parabens such as methyl or propyl paraben, catechol, resorcinol, cyclohexanol, 3-pentanol, and m-cresol), low molecular weight (less than about 10 residues) polypeptides, proteins, such as serum albumin, gelatin, or lmmunoglobuhns, hydrophihc polymers such as polyvinylpyrrohdone, ammo acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine, monosacchaπdes, disacchaπdes, and other carbohydrates including glucose, mannose, or dextπns, chelating agents such as EDTA, sugars such as sucrose, mannitol, trehalose or sorbitol, salt-forming counter-ions such as sodium, metal complexes (e g Zn-protein complexes), and or non- lonic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG) Prefeπed lyophihzed anti- ErbB2 antibody formulations are described in WO 97/04801 , expressly incorporated herein by reference The formulation herein may also contain more than one active compound as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other For example, it may be desirable to further provide antibodies which bind to EGFR, ErbB2 (e g an antibody which binds a different epitope on ErbB2), ErbB3, ErbB4, or vascular endothehal factor (VEGF) in the one formulation Alternatively, or additionally, the composition may further comprise a chemotherapeutic agent, cytotoxic agent, cytokine, growth inhibitory agent, anti-hormonal agent, and or cardioprotectant Such molecules are suitably present in combination in amounts that are effective for the purpose intended The active ingredients may also be entrapped in microcapsules prepared, tor example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly- (methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions Such techniques are disclosed in Remington 's Pharmaceutical Sciences 16th edition, Osol, A Ed (1980) Sustained-release preparations may be prepared Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing the antibody, which matrices are in the form of shaped articles, e g films, or microcapsules Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vιnylalcohol)), polylactides (U S Pat No 3,773,919), copolymers of L-glutamic acid and γ ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycohc acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid-glycohc acid copolymer and leuprohde acetate), and poly-D-(-)-3-hydroxybutyπc acid The formulations to be used for in vivo administration must be sterile This is readily accomplished by filtration through sterile filtration membranes IV. Treatment with the Anti-ErbB2 Antibodies According to the present invention, the antι-ErbB2 antibody is used to treat prostate cancer, such as androgen independent prostate cancer or androgen dependent prostate cancer Where the cancer to be treated is androgen independent or dependent prostate cancer, expression of the androgen (e g andosterone or testosterone) and/or its cognate receptor in the tumor may be assessed using any of the various assays available, e g as described above Alternatively, or additionally, a patient may be diagnosed as having androgen independent prostate cancer in that they no longer respond to anti-androgen therapy and the patient diagnosed as having androgen dependent prostate cancer may be one who responds to anti-androgen therapy The cancer will generally comprise ErbB2- expressing cells, such that the antι-ErbB2 antibody is able to bind thereto While the cancer may be characterized by overexpression of the ErbB2 receptor, the present application further provides a method for treating cancer which is not considered to be an ErbB2-overexpressιng cancer To determine ErbB2 expression in the cancer, various diagnostic/prognostic assays are available In one embodiment, ErbB2 overexpression may be analyzed by IHC, e g using the HERCEPTEST® (Dako) Parrafin embedded tissue sections from a tumor biopsy may be subjected to the IHC assay and accorded a ErbB2 protein staining intensity criteria as follows Score 0 no staining is observed or membrane staining is observed in less than 10% of tumor cells Score 1+ a faint/barely perceptible membrane staining is detected in more than 10% of the tumor cells The cells are only stained in part of their membrane Score 2+ a weak to moderate complete membrane staining is observed in more than 10% of the tumor cells Score 3+ a moderate to strong complete membrane staining is observed in more than 10% of the tumor cells Those tumors with 0 or 1+ scores for ErbB2 overexpression assessment may be characterized as not overexpressing ErbB2, whereas those tumors with 2+ or 3+ scores may be characterized as overexpressing ErbB2 Alternatively, or additionally, FISH assays such as the INFORM™ (sold by Ventana, Arizona) or PATHVISION™ (Vysis, Illinois) may be carried out on formalin-fixed, paraffin-embedded tumor tissue to determine the extent (if any) of ErbB2 overexpression in the tumor The prostate cancer to be treated herein may be one characterized by excessive activation of an ErbB receptor, e g EGFR Such excessive activation may be attributable to overexpression or increased production of the ErbB receptor or of an ErbB ligand In one embodiment of the invention, a diagnostic or prognostic assay will be performed to determine whether the patient's cancer is characterized by excessive activation of an ErbB receptor For example, ErbB gene amplification and/or overexpression of an ErbB receptor in the cancer may be determined Various assays for determining such amphfication/overexpression are available in the art and include the IHC, FISH and shed antigen assays described above Alternatively, or additionally, levels of an ErbB ligand, such as TGF-α, in or associated with the tumor may be determined according to known procedures Such assays may detect protein and or nucleic acid encoding it in the sample to be tested In one embodiment, ErbB ligand levels in the tumor may be determined using lmmunohistochemistry (IHC), see, for example, Scher et al Clin Cancer Research 1 545-550 ( 1995) Alternatively, or additionally, one may evaluate levels of ErbB ligand-encoding nucleic acid in the sample to be tested, e g via FISH, southern blotting, or PCR techniques Moreover, ErbB receptor or ErbB ligand overexpression or amplification may be evaluated using an in vivo diagnostic assay, e g by administering a molecule (such as an antibody) which binds the molecule to be detected and is tagged with a detectable label (e g a radioactive isotope) and externally scanning the patient for localization of the label In certain embodiments, an immunoconjugate comprising the antι-ErbB2 antibody conjugated with a cytotoxic agent is administered to the patient Preferably, the immunoconjugate and/or ErbB2 protein to which it is bound is/are internalized by the cell, resulting in increased therapeutic efficacy of the immunoconjugate in killing the cancer cell to which it binds In a preferred embodiment, the cytotoxic agent targets or interferes with nucleic acid in the cancer cell Examples of such cytotoxic agents include maytansinoids, cahcheamicins, πbonucleases and DNA endonucleases The antι-ErbB2 antibodies or immunoconjugates are administered to a human patient, in accord with known methods, such as intravenous administration, e g , as a bolus or by continuous infusion over a period of time, by intramuscular, lntrapeπtoneal, intracerobrospinal, subcutaneous, intra-articular, intrasynovial, intrathecal, oral, topical, or inhalation routes Intravenous or subcutaneous administration of the antibody is preferred Other therapeutic regimens may be combined with the administration of the antι-ErbB2 antibody The combined administration includes coadministration, using separate formulations or a single pharmaceutical formulation, and consecutive administration in either order, wherein preferably there is a time period while both (or all) active agents simultaneously exert their biological activities In one preferred embodiment, the patient is treated with two different antι-ErbB2 antibodies For example, the patient may be treated with a first antι-ErbB2 antibody which blocks ligand activation of an ErbB receptor or an antibody having a biological characteristic of monoclonal antibody 2C4 as well as a second anti- ErbB2 antibody which is growth inhibitory (e g HERCEPTIN®) or an antι-ErbB2 antibody which induces apoptosis of an ErbB2-overexpressιng cell (e g 7C2, 7F3 or humanized variants thereof* Preferably such combined therapy results in a synergistic therapeutic effect It may also be desirable to combine administration of the antι-ErbB2 antibody or antibodies, with administration of an antibody directed against another tumor associated antigen The other antibody in this case may, for example, bind to EGFR, ErbB3, ErbB4, or vascular endothehal growth factor (VEGF) In one embodiment, the treatment of the present invention involves the combined administration of an antι-ErbB2 antibody (or antibodies) and one or more chemotherapeutic agents or growth inhibitory agents, including coadministration of cocktails of different chemotherapeutic agents Preferred chemotherapeutic agents include taxanes (such as paclitaxel and docetaxel) and or anthracychne antibiotics Preparation and dosing schedules for such chemotherapeutic agents may be used according to manufacturers' instructions or as determined empirically by the skilled practitioner Preparation and dosing schedules for such chemotherapy are also described in Chemotherapy Service Ed , M C Perry, Williams & Wilkins, Baltimore, MD (1992) The antibody may be combined with an anti-hormonal compound, e g , an anti-estrogen compound such as tamoxifen, an anti-progesterone such as onapπstone (see, EP 616 812), or an anti-androgen such as flutamide, in dosages known for such molecules Where the cancer to be treated is androgen independent cancer, the patient may previously have been subjected to anti-androgen therapy and, after the cancer becomes androgen independent, the antι-ErbB2 antibody (and optionally other agents as described herein) may be administered to the patient Sometimes, it may be beneficial to also coadminister a cardioprotectant (to prevent or reduce myocardial dysfunction associated with the therapy) or one or more cytokines to the patient In addition to the above therapeutic regimes, the patient may be subjected to surgical removal of cancer cells and/or radiation therapy Suitable dosages for any of the above coadministered agents are those presently used and may be lowered due to the combined action (synergy) of the agent and antι-ErbB2 antibody For the prevention or treatment of disease, the appropriate dosage of antibody will depend on the type of disease to be treated, as defined above, the severity and course of the disease, whether the antibody is administered for preventive or therapeutic purposes, previous therapy, the patient's clinical history and response to the antibody, and the discretion of the attending physician The antibody is suitably administered to the patient at one time or over a series of treatments Depending on the type and severity of the disease, about 1 μg/kg to 15 mg/kg (e g 0 1- 20mg/kg) of antibody is an initial candidate dosage for administration to the patient, whether, for example, by one or more separate administrations, or by continuous infusion A typical daily dosage might range from about 1 μg/kg to 100 mg/kg or more, depending on the factors mentioned above For repeated administrations over several days or longer, depending on the condition, the treatment is sustained until a desired suppression of disease symptoms occurs A preferred dosing regimen comprises administering an initial loading dose of about 4 mg/kg, followed by a weekly maintenance dose of about 2 mg/kg of the antι-ErbB2 antibody However, other dosage regimens may be useful The progress of this therapy is easily monitored by conventional techniques and assays Aside from administration of the antibody protein to the patient, the present application contemplates administration of the antibody by gene therapy Such administration of nucleic acid encoding the antibody is encompassed by the expression "administering a therapeutically effective amount of an antibody" See, for example, WO96/07321 published March 14, 1996 concerning the use of gene therapy to generate intracellular antibodies There are two majc-r approaches to getting the nucleic acid (optionally contained in a vector) into the patient s cells, in vivo and e;c vivo For in vivo delivery the nucleic acid is injected directly into the patient, usually at the site where the antibody is required For ex vivo treatment, the patient s cells are removed, the nucleic acid is introduced into these isolated cells and the modified cells are administered to the patient either directly or, tor example, encapsulated within porous membranes which are implanted into the patient (see, e g U S Patent Nos 4,892,538 and 5,283, 187) There are a variety of techniques available for introducing nucleic acids into viable cells The techniques vary depending upon whether the nucleic acid is transferred into cultured cells in vitro, or in vivo in the cells of the intended host Techniques suitable for the transfer of nucleic acid into mammalian cells in vitro include the use of liposomes, electroporation, microinjection, cell fusion, DEAE-dextran, the calcium phosphate precipitation method, etc A commonly used vector for ex vivo delivery of the gene is a retrovirus The currently preferred in vivo nucleic acid transfer techniques include transfection with viral vectors (such as adenovirus, Herpes simplex I virus, or adeno-associated virus) and hpid-based systems (useful hpids for hpid- mediated transfer of the gene are DOTMA, DOPE and DC-Choi, for example) In some situations it is desirable to provide the nucleic acid source with an agent that targets the target cells, such as an antibody specific for a cell surface membrane protein or the target cell, a ligand for a receptor on the target cell, etc Where hposomes are employed, proteins which bind to a cell surface membrane protein associated with endocytosis may be used for targeting and or to facilitate uptake, e g capsid proteins or fragments thereof tropic for a particular cell type, antibodies for proteins which undergo internalization in cycling, and proteins that target intracellular localization and enhance intracellular half-life The technique of receptor-mediated endocytosis is described, for example, by Wu et al , J Biol Chem 262 4429-4432 (1987), and Wagner et al , Proc Natl Acad Sci USA SI 3410-3414 (1990) For review of the currently known gene marking and gene therapy protocols see Anderson et al , Science 256 808-813 (1992) See also WO 93/25673 and the references cited therein V. Articles of Manufacture In another embodiment of the invention, an article of manufacture containing materials useful for the treatment of prostate cancer is provided The article of manufacture comprises a container and a label or package insert on or associated with the container Suitable containers include, for example, bottles, vials, syringes, etc The containers may be formed from a variety of materials such as glass or plastic The container holds a composition which is effective for treating the condition and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle) At least one active agent in the composition is the antι-ErbB2 antibody The label or package insert indicates that the composition is used for treating prostate cancer, androgen independent prostate cancer, or androgen dependent prostate cancer Moreover, the article of manufacture may comprise (a) a first container with a composition contained therein, wherein the composition comprises a first antibody which binds ErbB2 and inhibits growth of cancer cells which overexpress ErbB2, and (b) a second container with a composition contained therein, wherein the composition comprises a second antibody which binds ErbB2 and blocks ligand activation of an ErbB receptor The article of manufacture in this embodiment of the invention may turther comprises a package insert indicating that the first and second antibody compositions can be used to treat prostate cancer Alternatively, or additionally, the article of manufacture may further comprise a second (or third) container comprising a pharmaceut'cally-acceptable buffer, such as bacteπostatic water for injection (BWFI), phosphate-buffered saline, Ringer's solution and dextrose solution It may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes VI. Deposit of Materials The following hybπdoma cell lines have been deposited with the American Type Culture Collection, 10801 University Boulevard, Manassas, V A 201 10-2209, USA (ATCC) Antibody Designation ATCC No Deposit Date 7C2 ATCC HB-12215 October 17, 1996 7F3 ATCC HB-1221 October 17, 1996 4D5 ATCC CRL 10463 May 24, 1990 2C4 ATCC HB12697 April 8, 1999 Further details of the invention are illustrated by the following non-limiting Examples The disclosures of all citations in the specification are expressly incorporated herein by reference Example 1 Production and Characterization of Monoclonal Antibody 2C4 The murine monoclonal antibodies 2C4, 7F3 and 4D5 which specifically bind the extracellular domain of ErbB2 were produced as described in Fendly et al , Cancer Research 50 1550-1558 (1990) Briefly, NIH 3T3/HER2-3 400 cells (expressing approximately 1 x 10 ErbB2 molecules/cell) produced as described in Hudziak et al Proc Natl Acad Sci (USA) 84 7158-7163 (1987) were harvested with phosphate buffered saline (PBS) containing 25mM EDTA and used to immunize BALB/c mice The mice were given injections I p of 10 cells in 32 0 5ml PBS on weeks 0, 2, 5 and 7 The mice with antisera that lmmunoprecipitated P-labeled ErbB2 were given i p injections of a wheat germ agglutinin-Sepharose (WGA) purified ErbB2 membrane extract on weeks 9 and 13 This was followed by an l v injection ofO 1 ml ofthe ErbB2 preparation and the splenocytes were fused with mouse myeloma line X63-Ag8 653 Hybπdoma supernatants were screened for ErbB2-bιndιng by ELISA and radioimmunoprecipitation The ErbB2 epitopes bound by monoclonal antibodies 4D5, 7F3 and 2C4 were determined by competitive binding analysis (Fendly et al Cancer Research 50 1550-1558 (1990)) Cross-blocking studies were done on antibodies by direct fluorescence on intact cells by using the PANDEX™ Screen Machine to quantitate fluorescence Each monoclonal antibody was conjugated with fluorescein isothiocyanate (FITC), using established procedures (Wofsy et al Selected Methods in Cellular Immunology, p 287, Mishel and Schngi (eds ) San Francisco W J Freeman Co ( 1980)) Confluent monolayers of NIH 3T3/HER2-3 400 cells were trypsinized, washed once, and resuspended at 1 75 x 10 cell/ml in cold PBS containing 0 5% bovine serum albumin (BSA) and 0 1 % NaN 3 A final concentration of 1 % latex particles (IDC, Portland, OR) was added to reduce clogging of the PANDEX™ plate membranes Cells in suspension, 20 μl, and 20 μl of purified monoclonal antibodies ( lOOμg/ml to 0 1 μg/ml) were added to the PANDEX™ plate wells and incubated on ice for 30 minutes A predetermined dilution of FITC-labeled monoclonal antibodies in 20 μl was added to each well, incubated tor 30 minutes, washed, and the fluorescence was quantitated by the PANDEX™ Monoclonal antibodies were considered to share an epitope if each blocked binding of the other by 50% or greater in comparison to an irrelevant monoclonal antibody control In this experiment, monoclonal antibodies 4D5, 7F3 and 2C4 were assigned epitopes I, G F and F, respectively The growth inhibitory characteristics of monoclonal antibodies 2C4, 7F3 and 4D5 were evaluated using the breast tumor cell line, SK-BR-3 (see Hudziak etal Molec Cell Biol 9(3) 1 165-1 172 (1989)) Briefly, SK-BR-3 cells were detached by using 0 25% (vol/vol) trypsin and suspended in complete medium at a density of 4 x 10 cells 4 per ml Ahquots of 100 μl (4 x 10 cells) were plated into 96-well microdilution plates, the cells were allowed to adhere, and 100 μl of media alone or media containing monoclonal antibody (final concentration 5 μg/ml) was then added After 72 hours, plates were washed twice with PBS (pH 7 5), stained with crystal violet (0 5% in methanol), and analyzed tor relative cell proliferation as described in Sugarman et al Science 230 943-945 (1985) Monoclonal antibodies 2C4 and 7F3 inhibited SK-BR-3 relative cell proliferation by about 20% and about 38%, respectively, compared to about 56% inhibition achieved with monoclonal antibody 4D5 Monoclonal antibodies 2C4, 4D5 and 7F3 were evaluated for their ability to inhibit HRG-stimulated tyrosine phosphorylation of proteins in the M x 180,000 range from whole-cell lysates of MCF7 cells (Lewis et al Cancer Research 56 1457-1465 (1996)) MCF7 cells are reported to express all known ErbB receptors, but at relatively low levels Since ErbB2, ErbB3, and ErbB4 have nearly identical molecular sizes, it is not possible to discern which protein is becoming tyrosine phosphorylated when whole-cell lysates are evaluated by Western blot analysis However, these cells are ideal for HRG tyrosine phosphorylation assays because under the assay conditions used, in the absence of exogenously added HRG, they exhibit low to undetectable levels of tyrosine phosphorylation proteins in the M 180,000 range MCF7 cells were plated in 24-well plates and monoclonal antibodies to ErbB2 were added to each well and incubated for 30 minutes at room temperature, then rHRGβl 1 - 44 was added to each well to a final concentration of 0 2 nM, and the incubation was continued for 8 minutes Media was carefully aspirated from each well, and reactions were stopped by the addition of 100 μl of SDS sample buffer (5% SDS, 25 mM DTT, and 25 mM Tπs-HCl, pH 6 8) Each sample (25 μl) was electrophoresed on a 4-12% gradient gel (Novex) and then electrophoretically transferred to polyvinyhdene difluoπde membrane Antiphosphotyrosine (4G10, from UBI, used at 1 μg ml) immunoblots were developed, and the intensity of the predominant reactive band at r ~ 180,000 was quantified by reflectance densitometry, as described previously (Holmes etal Science 256 1205-1210 (1992), Shwkowski et al J Biol Chem 269 14661-14665 (1994)) Monoclonal antibodies 2C4, 7F3, and 4D5, significantly inhibited the generation of a HRG- mduced tyrosine phosphorylation signal at M τ 180,000 In the absence of HRG, none of these antibodies were able to stimulate tyrosine phosphorylation of proteins in the M, 180,000 range Also, these antibodies do not cross-react with EGFR (Fendly et al Cancer Research 50 1550-1558 (1990)), ErbB3, or ErbB4 Antibodies 2C4 and 7F3 significantly inhibited HRG stimulation of pi 80 tyrosine phosphorylation to <25% of control Monoclonal antibody 4D5 was able to block HRG stimulation of tyrosine phosphorylation by -50% Fig 2A shows dose- response curves for 2C4 or 7F3 inhibition of HRG stimulation of pi 80 tyrosine phosphorylation as determined by reflectance densitometry Evaluation of these inhibition curves using a 4-parameter fit yielded an IC 50 of 2 8 ± 0 7 nM and 29 0 ± 4 1 nM for 2C4 and 7F3, respectively Inhibition of HRG binding to MCF7 breast tumor cell lines by antι-ErbB2 antibodies was performed with monolayer cultures on ice in a 24-well-plate format (Lewis et al Cancer Research 56 1457-1465 ( 1996)) 125 Antι-ErbB2 monoclonal antibodies were added to each well and incubated for 30 minutes I-labeled rHRGβl 177-2?4 (25 pm) was added, and the incubation was continued for 4 to 16 hours Fig 2B provides dose- response curves for 2C4 or 7F3 inhibition of HRG binding to MCF7 cells Varying concentrations of 2C4 or 7F3 125 were incubated with MCF7 cells in the presence of I-labeled rHRGβl , and the inhibition curves are shown in Fig 2B Analysis of these data yielded an IC 50 of 2 4 ± 0 3 nM and 19 0 ± 7 3 nM for 2C4 and 7F3, respectively A maximum inhibition of -74% for 2C4 and 7F3 were in agreement with the tyrosine phosphorylation data To determine whether the effect of the antι-ErbB2 antibodies observed on MCF7 cells was a general 125 phenomenon, human tumor cell lines were incubated with 2C4 or 7F3 and the degree of specific I-labeled rHRGβl binding was determined (Lewis etal Cancer Research 56 1457 1465 (1996)) The results from this study 121 are shown in Fig 3 Binding of I-labeled rHRGβl could be significantly inhibited by either 2C4 or 7F3 in all cell lines, with the exception of the breast cancer cell line MDA-MB-468, which has been reported to express little or no ErbB2 The remaining cell lines are reported to express ErbB2, with the level of ErbB2 expression varying widely among these cell lines In fact, the range of ErbB2 expression in the cell lines tested varies by more than 2 4 orders of magnitude For example, BT-20, MCF7, and Caov3 express - 10 ErbB2 receptors/cell, whereas BT-474 and SK-BR-3 express - 10 ErbB2 receptors/cell Given the wide range of ErbB2 expression in these cells and the data above, it was concluded that the interaction between ErbB2 and ErbB3 or ErbB4, was itself a high-affinity interaction that takes place on the surface of the plasma membrane The growth inhibitory effects of monoclonal antibodies 2C4 and4D5 on MDA-MB-175 and SK-BR-3 cells in the presence or absence of exogenous rHRGβl was assessed (Schaefer et al Oncogene 15 1385-1394 (1997)) ErbB2 levels in MDA-MB-175 cells are 4-6 times higher than the level found in normal breast epithelial cells and the ErbB2-ErbB4 receptor is constitutively tyrosine phosphorylated in MD A-MB- 175 cells MDA-MB- 175 cells were treated with an antι-ErbB2 monoclonal antibodies 2C4 and 4D5 (l Oμg/mL) for 4 days In a crystal violet staining assay, incubation with 2C4 showed a strong growth inhibitory effect on this cell line (Fig 4A) Exogenous HRG did not significantly reverse this inhibition On the other hand 2C4 revealed no inhibitory effect on the ErbB2 overexpressing cell line SK-BR-3 (Fig 4B) Monoclonal antibody 2C4 was able to inhibit cell proliferation of MDA-MB-175 cells to a greater extent than monoclonal antibody 4D5, both in the presence and absence of exogenous HRG Inhibition of cell proliferation by 4D5 is dependent on the ErbB2 expression level (Lewis et al Cancer Immunol Immunother 37 255-263 (1993)) A maximum inhibition of 66% in SK-BR-3 cells could be detected (Fig 4B) However this effect could be overcome by exogenous HRG Example 2 HRG Dependent Association of ErbB2 with ErbB3 is Blocked by Monoclonal Antibody 2C4 The ability of ErbB3 to associate with ErbB2 was tested in a co-immunoprecipitation experiment 1 0 x 10 MCF7 or SK-BR-3 cells were seeded in six well tissue culture plates in 50 50 DMEM/Ham's F12 medium containing 10% fetal bovine serum (FBS) and 10 mM HEPES, pH 7 2 (growth medium), and allowed to attach overnight The cells were starved for two hours in growth medium without serum prior to beginning the experiment The cells were washed briefly with phosphate buffered saline (PBS) and then incubated with either 100 nM of the indicated antibody diluted in 0 2% w/v bovine serum albumin (BSA), RPMI medium, with 10 mM HEPES, pH 7 2 (binding buffer), or with binding buffer alone (control) After one hour at room temperature, HRG was added to a final concentration of 5 nM to half the wells (+) A similar volume of binding buffer was added to the other wells (-) The incubation was continued for approximately 10 minutes Supernatants were removed by aspiration and the cells were lysed in RPMI, 10 mM HEPES, pH 7 2, 1 0% v/v TRITON X-100™, 1 0% w/v CHAPS (lysis buffer), containing 0 2 mM PMSF, 10 μg ml leupeptin, and 10 TU/ml aprotinin The lysates were cleared of insoluble material by centπfugation ErbB2 was immunoprecipitated using a monoclonal antibody covalently coupled to an affinity gel (Affi- Prep 10, Bio-Rad) This antibody (Ab 3, Oncogene Sciences) recognizes a cytoplasmic domain epitope Immunoprecipitation was performed by adding 10 μl of gel slurry containing approximately 8 5 μg of immobilized antibody to each lysate, and the samples were allowed to mix at room temperature for two hours The gels were then collected by centπfugation The gels were washed batchwise three times with lysis buffer to remove unbound material SDS sample buffer was then added and the samples were heated briefly in a boiling water bath Supernatants were run on 4-12% polyacrylamide gels and electroblotted onto nitrocellulose membranes The presence of ErbB3 was assessed by probing the blots with a polyclonal antibody against a cytoplasmic domain epitope thereof (c-17, Santa Cruz Biotech) The blots were visualized using a chemiluminescent substrate (ECL, Amersham) As shown in the control lanes of Figs 5A and 5B, for MCF7 and SK-BR-3 cells, respectively, ErbB3 was present in an ErbB2 immunoprecipitate only when the cells were stimulated with HRG If the cells were first incubated with monoclonal antibody 2C4, the ErbB3 signal was abolished in MCF7 cells (Fig 5A, lane 2C4 +) or substantially reduced in SK-BR-3 cells (Fig 5B, lane 2C4+) As shown in Figs 5A-B, monoclonal antibody 2C4 blocks heregulin dependent association of ErbB3 with ErbB2 in both MCF7 and SK-BR-3 cells substantially more effectively than HERCEPTIN® Preincubation with HERCEPTIN® decreased the ErbB3 signal in MCF7 lysates but had little or no effect on the amount of ErbB3 co-precipitated from SK-BR-3 lysates Preincubation with an antibody against the EGF receptor (Ab-1 , Oncogene Sciences) had no effect on the ability of ErbB3 to co- lmmunoprecipitate with ErbB2 in either cell line Example 3 Humanized 2C4 Antibodies and Affinity Matured 2C4 Antibody Variants The variable domains of murine monoclonal antibody 2C4 were first cloned into a vector which allows production of a mouse/human chimenc Fab fragment Total RNA was isolated from the hybπdoma cells using a Stratagene RNA extraction kit following manufacturer's protocols The variable domains were amplified by RT- PCR, gel purified, and inserted into a derivative of a pUCl 19-based plasmid containing a human kappa constant domain and human C H 1 domain as previously described (Carter et al PNAS (USA) 89 4285 (1992), and U S Patent No 5,821 ,337) The resultant plasmid was transformed into E coh strain 16C9 for expression of the Fab fragment Growth of cultures, induction of protein expression, and purification of Fab fragment were as previously described (Werther et al J Immunol 157 4986-4995 (1996), Presta et al Cancer Research 51 4593- 4599 ( 1997)) Purified chimenc 2C4 Fab fragment was compared to the muπne parent antibody 2C4 with respect 125 to its ability to inhibit I-HRG binding to MCF7 cells and inhibit rHRG activation of pi 80 tyrosine phosphorylation in MCF7 cells As shown in Fig 6A, the chimenc 2C4 Fab fragment is very effective in disrupting the formation of the high affinity ErbB2-ErbB3 binding site on the human breast cancer cell line, MCF7 The relative IC 50 value calculated for intact murine 2C4 is 4 0 ± 04nM, whereas the value for the Fab fragment is 7 7 + 1 InM As illustrated in Fig 6B, the monovalent chimenc 2C4 Fab fragment is very effective in disrupting HRG-dependent ErbB2-ErbB3 activation The IC 50 value calculated for intact murine monoclonal antibody 2C4 is 6 0 ± 2nM, whereas the value for the Fab fragment is 15 0 ± 2nM DNA sequencing of the chimenc clone allowed identification of the CDR residues (Kabat etal , Sequences of Proteins of Immunological Interest, 5 lh Ed Public Health Service, National Institutes of Health, Bethesda, MD (1991)) (Figs 7 A and B) Using o gonucleotide site-directed mutagenesis, all six of these CDR regions were introduced into a complete human framework (V L kappa subgroup I and V H subgroup III) contained on plasmid VX4 as previously described (Presta et al , Cancer Research 57 4593-4599 ( 1997)) Protein from the resultant "CDR-swap" was expressed and purified as above Binding studies were performed to compare the two versions Briefly, a NUNC MAXISORP™ plate was coated with 1 microgram per ml of ErbB2 extracellular domain (ECD, produced as described in WO 90/14357) in 50 mM carbonate buffer, pH 9 6, overnight at 4 C C, and then blocked with ELISA diluent (0 5% BSA, 0 05% polysorbate 20, PBS) at room temperature for 1 hour Serial dilutions of samples in ELISA diluent were incubated on the plates for 2 hours After washing, bound Fab fragment was detected with biotinylated murine anti-human kappa antibody (ICN 634771 ) followed by streptavidin-conjugated horseradish peroxidase (Sigma) and using 3,3',5,5 -tetramethyl benzidine (Kirkegaard & Perry Laboratories, Gaithersburg, MD) as substrate Absorbance was read at 450 nm As shown in Fig 8A, all binding was lost on construction of the CDR-swap human Fab fragment To restore binding of the humanized Fab, mutants were constructed using DNA from the CDR-swap as template Using a computer generated model (Fig 9), these mutations were designed to change human framework region residues to their murine counterparts at positions where the change might affect CDR conformations or the antibody-antigen interface Mutants are shown in Table 2 Table 2 Designation of Humanized 2C4 FR Mutations Binding curves for the various mutants are shown in Figs 8A-C Humanized Fab version 574, with the changes ArgH71Val, AspH73Arg and IleH69Leu, appears to have binding restored to that of the original chimenc 2C4 Fab fragment Additional FR and or CDR residues, such as L2, L54, L55, L56, H35 and/or H48, may be modified (e g substituted as follows - IleL2Thr, ArgL54Leu, TyrL55Glu, ThrL56Ser, AspH35Ser, and ValH48Ile) in order to further refine or enhance binding of the humanized antibody Alternatively, or additionally, the humanized antibody may be affinity matured (see above) in order to further improve or refine its affinity and/or other biological activities Humanized 2C4 version 574 was affinity matured using a phage-display method Briefly, humanized 2C4 574 Fab was cloned into a phage display vector as a genelll fusion When phage particles are induced by infection with M13K07 helper phage, this fusion allows the Fab to be displayed on the N-terminus of the phage tail-fiber protein, genelll (Baca et al J Biol Chem 272 10678 (1997)) Individual libraries were constructed for each of the 6 CDRs identified above In these libraries, the amino acids in the CDRs which were identified using a computer generated model (Fig 9) as being potentially significant in binding to ErbB2 were randomized using oligos containing "NNS" as their codons The libraries were then panned against ErbB2 ECD coated on NUNC MAXISORP™ plates with 3% dry milk in PBS with 0 2% TWEEN 20® (MPBST) used in place of all blocking solutions In order to select for phage with affinities higher than that of 2C4 574, in panning rounds 3, 4, and 5, soluble ErbB2 ECD or soluble Fab 2C4 574 was added during the wash steps as competitor Wash times were extended to 1 hour at room temperature After 5 rounds of panning, individual clones were again analyzed by phage-ELISA Individual clones were grown in Costar 96-well U-bottomed tissue culture plates, and phage were induced by addition of helper phage After overnight growth, E colt cells were pelleted, and the phage-containing supernates were transfered to 96-well plates where the phage were blocked with MPBST for 1 hr at room temperature NUNC MAXISORP™ plates coated with ErbB2 ECD were also blocked with MPBST as above Blocked phage were incubated on the plates for 2 hours After washing, bound phage were detected using horseradish-peroxidase-conjugated anti-Mi 3 monoclonal antibody (Amersham Pharmacia Biotech, Inc 27-9421-01 ) diluted 1 5000 in MPBST, followed by 3,3',5,5',-tetramefhyl benzidine as substrate Absorbance was read at 450 nm The 48 clones from each library which gave the highest signals were DNA sequenced Those clones whose sequences occurred the most frequently were subcloned into the vector described above which allows expression of soluble Fabs These Fabs were induced, proteins purified and the purified Fabs were analyzed for binding by ELISA as described above and the binding was compared to that of the starting humanized 2C4 574 version After interesting mutations in individual CDRs were identified, additional mutants which were various combinations of these were constructed and tested as above Mutants which gave improved binding relative to 574 are described in Table 3 Table 3 Designation of mutants derived from affinity maturation of 2C4.574 Mutant Name Change from 574 Mutant/574* H3 Al serH99trp, metH341eu 0 380 L2 F5 serL50trp, tyrL53gly, mefH341eu 0 087 HI 3 B3 thrH28gln,thrH30ser, metH341eu 0 572 L3 G6 tyrL92pro, ιleL931ys, metH341eu 0 569 L3 G1 1 tyrL92ser, ιleL93arg, tyrL94gly, metH341eu 0 561 L3 29 tyrL92phe, tyrL96asn, mefH341eu 0 552 L3 36 tyrL92phe, tyrL941eu, tyrL96pro, metH341eu 0 215 654 serL50trp, metH341eu 0 176 655 metH34ser 0 542 659 serL50trp, mefH34ser 0 076 L2 F5 H3 A1 serL50trp, tyrL53gly, metH341eu, serH99trp 0 175 L3G6 H3 Al tyrL92pro, ιleL931ys, metH341eu, serH99trp 0 218 HI 3 B3 H3 A1 thrH28gln, thrH30ser, mefH341eu, serH99trp 0 306 L3 G11 H3 A1 tyrL92ser, ιleL93arg, tyrL94gly, metH341eu, serH99trp 0 248 654 H3 Al serL50trp, metH341eu, serH99trp 0 133 654 L3 G6 serL50trp, metH341eu, tyrL92pro, ιleL931ys 0 213 654 L3 29 serL50trp, metH341eu, tyrL92phe, tyrL96asn 0 236 654 L3 36 serL50trp, metH351eu, tyrL92phe, tyrL941eu, tyrL96pro 0 141 *Ratιo of the amount of mutant needed to give the mid-OD of the standard curve to the amount of 574 needed to give the mid-OD of the standard curve in an Erb2-ECD ELISA A number less than 1 0 indicates that the mutant binds Erb2 better than 574 binds The following mutants have also been constructed, and are currently under evaluation 659 L3 G6 serL50trp, metH34ser, tyrL92pro, ιleL931ys 659 L3 Gl 1 serL50trp, mefH34ser, tyrL92ser, ιleL93arg, tyrL94gly 659 L3 29 serL50trp, metH34ser, tyrL92phe, tyrL96asn 659 L3 36 serL50trp, metH34ser, tyrL92phe, tyrL941eu, tyrL96pro L2F5 L3G6 serL50trp, tyrL53gly, metH341eu, tyrL92pro, ιleL931ys L2F5 L3G11 serL50trp, tyrL53gly, metH341eu, tyrL92ser, ιleL93arg, tyrL94gly L2F5 L29 serL50trp, tyrL53gly, metH341eu, tyrL92phe, tyrL96asn L2F5 L36 serL50trp, tyrL53gly, metH341eu, tyrL92phe, tyrL941eu, tyrL96pro L2F5 L3G6 655 serL50trp, tyrL53gly, metH35ser, tyrL92pro, ιleL931ys L2F5 L3G1 1 655 serL50trp, tyrL53gly, metH34ser, tyrL92ser, ιleL93arg, tyrL94gly L2F5 L29 655 serL50trp, tyrL53gly, metH34ser, tyrL92phe, tyrL96asn L2F5 L36 655 serL50trp, tyrL53gly, metH34ser, tyrL92phe, tyrL941eu, tyrL96pro The following mutants, suggested by a homology scan, are currently being constructed 678 thrH30ala 679 thrH30ser 680 lysH64arg 681 leuH96val 682 thrL97ala 683 thrL97ser 684 tyrL96phe 685 tyrL96ala 686 tyrL91phe 687 thrL56ala 688 glnL28ala 689 glnL28glu The preferred amino acid at H34 would be methionine A change to leucine might be made if there were found to be oxidation at this position AsnH52 and asnH53 were found to be strongly preferred for binding Changing these residues to alanine or aspartic acid dramatically decreased binding An intact antibody comprising humanized Fab version 574 with a human IgGl heavy chain constant region has been prepared (see U S Patent No 5,821,337) The intact antibody is produced by Chinese Hamster Ovary (CHO) cells Example 4 Monoclonal Antibody 2C4 Blocks EGF. TGF-α or HRG Mediated Activation of MAPK Many growth factor receptors signal through the mitogen-activated protein kinase (MAPK) pathway These dual specificity kinases are one of the key endpoints in signal transduction pathways that ultimately triggers cancer cells to divide The ability of monoclonal antibody 2C4 or HERCEPΗN® to inhibit EGF, TGF-α or HRG activation of MAPK was assessed in the following way MCF7 cells (10 cells/well) were plated in serum containing media in 12-well cell culture plates The next day, the cell media was removed and fresh media containing 0 1 % serum was added to each well This procedure was then repeated the following day and prior to assay the media was replaced with serum-free binding buffer (Jones et al J Biol Chem 273 1 1667-74 (1998), and Schaefer et al J Biol Chem 274 859-66 (1999)) Cells were allowed to equilibrate to room temperature and then incubated for 30 minutes with 0 5 mL of 200 nM HERCEPΗN® or monoclonal antibody 2C4 Cells were then treated with 1 nM EGF, 1 nM TGF-α or 0 2 nM HRG for 15 minutes The reaction was stopped by aspirating the cell medium and then adding 0 2 mL SDS-PAGE sample buffer containing 1 % DTT MAPK activation was assessed by Western blotting using an anti-active MAPK antibody (Promega) as described previously (Jones et al J Biol Chem 273 1 1667-74 (1998)) As shown in Fig 10, monoclonal antibody 2C4 significantly blocks EGF, TGF α and HRG mediated activation of MAPK to a greater extent than HERCEPΗN® These data suggest that monoclonal antibody 2C4 binds to a surface of ErbB2 that is used for its association with either EGFR or ErbB3 and thus prevents the formation of the signaling receptor complex Example 5 Effect of HERCEPTIN® on the Growth of Androgen Dependent and Androgen Independent Human Prostate Cancer The effect of HERCEPΗN® monotherapy in androgen dependent and androgen independent prostate cancer xenograft models and the combination of HERCEPΗN® with paclitaxel were studied in prec nical models of human prostate cancer The androgen dependent CWR22 and LNCaP human prostate cancer xenograft models and androgen independent subhnes of CWR22 were used (Nagabhushan et al Cancer Res 56 3042-3046 ( 1996), Wainstein et al Cancer Res 54 6049-6052 ( 1994), and Stearns et al Prostate 36 56-58 ( 1998)) MATERIALS AND METHODS Animal studies Four to six week old nude athymic BALB/c male and female mice were obtained from the National Cancer Institute-Frederick Cancer Center and maintained in pressurized ventilated caging at the Sloan- Ketteπng Institute Male animals were inoculated s c with 1 x 10 LNCaP cells or minced tumor tissue from the androgen dependent CWR22, and females received the androgen independent subhnes CWR22R, or CWR22SA1 , CWRSA4, CWRSA6 which were obtained by selecting tumors for regrowth and increased serum PSA after androgen withdrawal All lines were injected together with reconstituted basement membrane (Matπgel, Collaborative Research, Bedford, MA) as described previously (Nagabhushan et al Cancer Res 56 3042-3046 (1996), Wainstein etal CancerRes 54 6049-6052 (1994), and Sato et al CancerRes 57 1584-1589 (1997)) To maintain serum testosterone levels, male mice were implanted with 12 5-mg sustained release testosterone pellets (Innovative Research of America, Sarasota, FL) s c before receiving the tumor cell inoculation Treatments consisted of twice weekly I p injection of 20 mg/kg HERCEPΗN® in PBS for no less than 3 weeks and/or paclitaxel (TAXOL ® , Bristol Myers-Squibb Company, Princeton, NJ) s c low dose (6 25mg kg s c , 5x/week x 3 weeks) or high dose (12 5 mg/kg s c , 5x/week x 2 weeks) in sterile saline Control mice were given vehicle alone Tumors were measured every 3-4 days with vernier calipers, and tumor volumes were calculated by the formula 2 3 p/6 x larger diameter x (smaller diameter) Animals with palpably established tumors of at least 65mm in volume were designated to treatment groups Determination of the ErbB2 status of the xenografts Xenografts were assayed for ErbB2 expression by immunohistochemistry using the DAKO ErbB2 kits (HERCEPTEST®, DAKO Corporation, Carpintena, CA) The samples were scored blindly by comparison with standard controls in the DAKO kit standards and scored as follows 0 (no staining, or membrane staining in less than 10% of the tumor cells), 1 + (faint membrane staining in more than 10% of the tumor cells), 2 + (weak to moderate complete membrane stain in >10% of cells), or 3 + (moderate to strong complete membrane staining in >10% of cells) A score of 0 or 1 + was considered negative for ErbB2 overexpression, whereas 2 + or 3 + indicated ErbB2 overexpression FISH analysis was done using the Oncor kits (INFORM® ErbB2 gene detection system, Oncor Inc , Gaithersburg, MD) A minimum of 100 tumor cells in each tumor was evaluated for nuclear ErbB2 gene copy number (Ross et al Hum Pathol 28 827-833 ( 1997)) Determination of Serum PSA Values Blood samples (-50 ml) from male mice collected in microtainer serum separator tubes (Becton Dickinson, Franklin Lakes, NJ) by superficial incision of the dorsal tail vein were taken prior to therapy, and on days 9 and 21 of treatment PSA values were then determined from serum using the Tandem-R PSA lmmunoradiometπc assay (Hybπtech, San Diego, CA) Statistical Analysis Pairwise differences between the tumor volumes of the treatment groups were compared over time using a permutation test The null hypothesis for this test is that treatment has no differential effect on the tumor volumes over time The statistic used to test the hypothesis was the sum of the squared differences between mean tumor volume summed over all time points SS_Dev was used in order to capture average differences between treatment groups at each time point This statistic reflects the amount by which the trajectories of average tumor volume of the two treatment groups are different RESULTS ErbBl immunohistochemtcal staining andErbB2 gene copy number of the prostate xenografts The ErbB2 expression patterns of the androgen dependent and androgen independent prostate xenografts were examined by immunohistochemistry (IHC) and FISH The parental androgen dependent CWR22 tumors demonstrated 2+ ErbB2 staining and the LNCaP tumors 3 + ErbB2 staining The androgen independent subhnes of CWR22 demonstrate 2 + (CWRSA1), 3+ (CWRSA4), 2+ (CWRSA6) and 1+ (CWR22R) staining for ErbB2 All tumors had a 2-4 ErbB2 gene copy (normal range) number by FISH Effects of HERCEPTIN® on established prostate cancer xenografts Animal experiments were preformed to evaluate the efficacy of HERCEPΗN® in well-established androgen dependent and androgen independent prostate cancer xenografts The CWR22, LNCaP, CWR22R and CWRSA6 models were used for these experiments because they provided reproducible growth curves HERCEPΗN® was administered lntrapeπtoneally (I p ) at a dose of 20 mg/kg twice weekly after the xenograft had been established No effect of HERCEPTIN® on tumor growth was observed in any of the androgen independent tumors when compared to controls (CWR22R, p=0 60, n=10, Fig HA, CWRSA6, p=0 63, n=10, Fιg 11B) The murine antι-ErbB2 antibody, 4D5, also had no effect on tumor growth in the CWR22R androgen independent line (p=0 21 , n=10) In contrast, HERCEPΗN® did show significant growth inhibition in both of the androgen dependent xenograft models, CWR22 (68% growth inhibition, p<0 03, n=12, Fig 1 1C) and LNCaP (89% growth inhibition, p=0 002, n=12, Fig 11D) Effects of HERCEPTIN® combined with TAXOL® on established tumor xenografts When paclitaxel and HERCEPΗN® were co-administered to animals there was a marked reduction in tumor volume versus control for both androgen dependent and androgen independent tumors (CWR22 98% growth inhibition, p<0 01 , Fig 1 IE, CWR22R 92% growth inhibition, p<0 01 , Fig 1 1G, LNCaP 94% growth inhibition, p=0 006, Fig 1 IF, CWRSA6 77% growth inhibition, p<0 01 , Fig 1 IH) Increased growth inhibition was observed with the combination of HERCEPΗN® and paclitaxel as compared to each agent alone at the end of the treatment period in the animals with androgen dependent xenografts (Figs 1 1E-H) the CWR22 group (mean tumor volumes, n=6 in each group, paclitaxel 408 mm 3 , HERCEPΗN® 520 mm 3 , paclitaxel and HERCEPΗN® 76 mm 3 , p<003 paclitaxel versus paclitaxel and HERCEPΗN®) and the LNCaP group (mean tumor volumes, n=6 in each group, paclitaxel 233 mm 3 , HERCEPΗN® 163 mm 3 , paclitaxel and HERCEPΗN® 82 mm 3 , p<0 03 paclitaxel versus paclitaxel and HERCEPΗN®) In addition, there was increased growth inhibition with the combination of HERCEPΗN® and paclitaxel versus each agent alone at the end of the treatment period in the animals with androgen independent xenografts (Figs 1 1 E-H) the CWRSA6 group (mean tumor volumes, n=5 in each group, paclitaxel 1 ,496 mm , HERCEPΗN® 2.941 mm 3 , paclitaxel and HERCEPΗN® 687 mm 3 , p<0 001 paclitaxel versus paclitaxel and HERCEPΗN®) and the CWR22R group (mean tumor volumes, n=5 in each group, paclitaxel 1 ,273 mm 3 , HERCEPΗN® 3,81 1 mm 3 , paclitaxel and HERCEPΗN® 592 mm 3 , p=0 095 paclitaxel versus paclitaxel and HERCEPΗN®) Effects of HERCEPTIN® on PSA index in the treated animals with androgen dependent xenografts As shown in Figs 12A and B, there was a significant increase in prostate specific antigen (PSA) index (ng PSA ml 3 serum/mm tumor) in HERCEPTIN®-treated androgen dependent groups compared with control (CWR22, 1864% versus -4%, p<00001, Fig 12A, LNCaP, 232% versus -68%, p<00001 , Fig 12B) There was also an increase in the PSA index after combination treatment with HERCEPΗN® and paclitaxel when compared with pretreatment values CONCLUSIONS In these prostate cancer model systems, HERCEPΗN® alone has clinical activity only in the androgen dependent tumors and has at least an additive effect on growth, in combination with paclitaxel, in both androgen dependent and androgen independent tumors Response to HERCEPΗN® did not correlate with the PSA levels, as the PSA index markedly increased in the HERCEPTIN®-treated group, while remaining constant in the control group Example 6 Effect of Monoclonal Antibody 2C4 on the Growth of Androgen Dependent and Androgen Independent Human Prostate Cancer The effect of an antibody, which blocks ligand activation of an ErbB receptor, on human prostate cancer was assessed In particular, response of xenograft tumors to HERCEPΗN®, monoclonal antibody 2C4, paclitaxel and combination 2C4/paclιtaxel treatment was determined using the androgen dependent tumor CWR22 and androgen independent tumors CWR22R and CWRSA6 described in Example 5 above The antibodies and paclitaxel were administered as described in Example 5 The response of the androgen dependent tumor CWR22 to therapy is shown in Figs 13 and 14 Results are given as mean tumor volume ± SE The tumor volumes of the animals depicted in Fig 13 demonstrate that HERCEPTIN® has clinical activity in this androgen dependent model, as does monoclonal antibody 2C4 The combination of monoclonal antibody 2C4 and TAXOL® demonstrates increased growth inhibition when compared with either 2C4 or TAXOL® alone (Fig 14, p=0 003) The response of the androgen independent tumors CWR22R and CWRSA6 to therapy with HERCEPΗN®, monoclonal antibody 2C4, paclitaxel or combination 2C4/pachtaxel treatment is shown in Figs 15-18 Results are given as mean tumor volume ± SE The tumor volumes of the animals depicted in Figs 15 and 17 demonstrate that HERCEPΗN® has little or no clinical activity in these androgen independent models, while monoclonal antibody 2C4 has clinical activity in these models The combination of monoclonal antibody 2C4 and TAXOL® demonstrates increased growth inhibition when compared with either monoclonal antibody 2C4 or TAXOL® alone (Figs 16 and 18, p=0 002) A Fab' fragment of rhuMAb 2C4 was expressed in E colt and conjugated to 20kD branched polyethylene glycol (PEG) as described in WO98/37200 , expressly incorporated herein by reference The ability of the murine 2C4 antibody (20mg/kg), rhuMAb 2C4 (20mg/kg), and the pegylated Fab fragment (PEG-Fab, 20 or 40mg/kg) to treat androgen independent prostate cancer in vivo was assessed using the above CWR22R xenograft All injections were given IP (N=5) The results of these studies are shown in Fig 23 These data demonstrate that the tumor inhibition seen with 2C4 in the CWR22R model does not require an intact, bivalent antibody Since these Fab fragments do not contain Fc, an immunological mechanism such as ADCC can likely be ruled out These results are consistent with that shown in Fig 6 utilizing an in vitro system and chimenc versions of the 2C4 Fab The observation that 2C4 inhibits tumor growth as a monovalent fragment also lends credence to the notion that this inhibition is a result of blocking ErbB2 ability to heterodimeπze with other ErbB family members and thus inhibits initiation of downstream signaling events Dose response studies were carried out using rhuMAb 4D5 in the CWR22R and MSKPC6 (Agus et al Cancer Research 59 4761-4764 (1999)) androgen independent prostate xenografts Animals were dosed IP with control, 6mg/kg loading dose then 3mg/kg twice weekly, 20mg/kg loading dose then lOmg/kg twice weekly, or 60mg/kg loading dose then 30mg/kg twice weekly The results of these studies are shown in Figs 24 and 25 These data demonstrate that 2C4 suppresses the growth of androgen-independent tumor xenografts in a dose dependent manner Furthermore, these results further confirm that this inhibition of tumor growth is due to 2C4 treatment and not an experimental artifact A summary of typical results from the studies in Examples 5 and 6 is shown in Fig 21 Example 7 TGF-α and HB-EGF levels in Androgen Dependent and Androgen Independent Human Prostate Cancer TGF-α and HB-EGF mRNA levels in CWR22 cells (androgen dependent) and CWR22R cells (androgen independent) were evaluated in this example MATERIALS AND METHODS mRNA Preparation Frozen tumor tissue was processed according to the Qiagen protocol (Qiagen Maxi Kit #75163) Briefly, homogenization of tissue was accomplished with a Bπnkman Polytron (Pt- 3000) homogenizer equipped with the PT-DA 3012/2 TS generator using 15 second pulses and then pausing for 30 seconds This process was repeated three times and the extract was loaded on to a Qiagen column and washed according to the manufacturer's specifications Columns were eluted with 1 mL of RNAse-free water and RNA content was determined by absorbance at 260 nm Since TGF-α and HB-EGF are expressed in the cell line MDA- MB-231 , total RNA from these cells was used as a standard for TGF-α and HB-EGF quantification Real Time Quantitative PCR TGF-α and HB-EGF mRNA was quantified using real time quantitative PCR or TaqMan technique as previously described (Gibson et al Genome Research 6 986-994 ( 1996) , and Held etal Genomic Research 6 986-994 (1996)) The sequence of the primer/probe sets used for this analysis are shown below TGF-α F 5 -GGACAGCACTGCCAGAGA -3' (SEQ ID NO 14) R 5'-CAGGTGATTACAGGCCAAGTAG -3' (SEQ ID NO 15) P 5'FAM-CCTGGGTGTGCCACAGACCTTCA-TAMRA-p-3' (SEQ ID NO 16) HB-EGF F 5'-TGAAGTTACCTCCAGGTTGGT-3' (SEQ ID NO 17) R 5'-AGACACATTCTGTCCATTTTCAA-3' (SEQ ID NO 18) P 5'-FAM-CAAGCTGCAAAGTGCCTTGCTCAT-TAMRA-p-3' (SEQ ID NO 19) where F and R are the forward and reverse primers respectively, and P is the flourescent labeled probe β-actin was used as a housekeeping gene Primer/probe sets for β-actin are β-actin F 5'-ATGTATCACAGCCTGTACCTG-3' (SEQ ID NO 20) R 5'-TTCTTGGTCTCTTCCTCCTTG-3' (SEQ ID NO 21 ) P 5'FAM-AGGTCTAAGACCAAGGAAGCACGCAA-TAMRA-p-3' (SEQ ID NO 22) TaqMan analysis was performed in a standard 96-well plate format Standard curves were constructed using 0 6-150 ng of mRNA for TGF-α and HB-EGF analysis and 9 4-150 ng for β-actin Each dilution was run in duplicate For tumor samples, lOOng was used for all genes analyzed RESULTS As shown in Figs 19-20, the androgen independent prostate tumor line, CWR22R, expressed significantly greater levels of the EGFR ligands TGF-α and HB-EGF in comparison to the androgen dependent cell line, CWR22 Specifically, TGF-α was expressed at levels 8-9 higher in the CWR22R tumor relative to the CWR22 tumor In a similar fashion, HB-EGF was expressed -19 fold higher in CWR22R versus CWR22 Example 8 Effect of 2C4 or HERCEPTIN ® on PSA Index in Animals With Androgen-Dependent Xenografts As shown in Fig 22, the PSA index (defined as ng PSA/mL serum/mm 1 tumor) was measured in the androgen-dependent animals at day 21 near the end of treatment There was a significant increase in the PSA index in HERCEPTIN®-treated, androgen-dependent animals, while the control animals showed a decrease in the PSA index (LNCaP control=0 6 relative to pretreatment value, HERCEPTIN® group=2 35 relative to pretreatment value at day 21, CWR22 control=l 0 relative to pretreatment value, HERCEPΗN® group=18 relative to pretreatment value at day 21 ) Relative PSA index decreased in the LNCaP untreated group, presumably secondary to increased necrosis with increasing tumor size In contrast, there was no significant effect of 2C4 on the PSA index of treated tumors compared with controls Without being limited to any one theory, a possible explanation for this phenomenon might be related to the degree of ErbB2 activation in prostate cancer cells ErbB2 activation may cause androgen-independent growth by crosstalk with the androgen receptor signaling pathway (Craft et al Nature Med 5 280-285 (1999)) In our model systems, HERCEPΗN® binding to ErbB2 led to increased cellular secretion of PSA in an androgen-independent fashion (Agus etal CancerRes 59 4761-4764 (1999)) This result further supports the notion of crosstalk between the ErbB2 and androgen receptor signaling pathways Example 9 Effect of 7C2 anti-ErbB2 Antibody on Androgen Dependent and Independent Xenografts The effect of monoclonal antibody 7C2 (ATCC HB-12215) which induces apoptosis of ErbB2 overexpressing cells was compared to that of monoclonal antibody 2C4 in the androgen dependent CWR22 xenograft Both antibodies were dosed at 20mg/kg twice per week As shown in Fig 26, like 2C4 and HERCEPTIN®, 7C2 is also effecu ve in treating androgen dependent prostate cancer The effect of 7C2 on androgen independent prostate cancer was also assessed using the CWR22R xenograft Fig 27 shows that 7C2 alone was not effective in this model, but was effective when combined with TAXOL® Example 10 Therapy of Relapsed or Refractory Metastatic Prostate Cancer RhuMAb 2C4 is a full-length, humanized monoclonal antibody (produced in CHO cells) directed against ErbB2 RhuMAb 2C4 blocks the associated of ErbB2 with other ErbB family members thereby inhibiting intracellular signaling through the ErbB pathway In contrast to HERCEPTIN®, rhuMAb 2C4 not only inhibits the growth of ErbB2 overexpressing tumors but also blocks growth of tumors that require ErbB hgand-dependent signaling RhuMAb 2C4 is indicated as a single agent for treatment of hormone-refractory (androgen independent) prostate cancer patients Primary endpoints for efficacy include overall survival compared to best available care (Mitoxantrone/Prednisone), when used as a single agent, and safety Secondary efficacy endpoints include time to disease progression, response rate, quality of life, pain and/or duration of response RhuMAb 2C4 is administered intravenously (IV) weekly or every three weeks at 2 or 4 mg/kg, respectively, until disease progression The antibody is supplied as a multi-dose liquid formulation (20mL fill at a concentration of 20mg/mL or higher concentration) RhuMAb 2C4 is also indicated in combination with chemotherapy for treatment of hormone-refractory (androgen independent) prostate cancer patients Primary endpoints for efficacy include overall survival compared to chemotherapy, and safety Secondary efficacy endpoints include time to disease progression, response rate, quality of life, pain and/or duration of response RhuMAb 2C4 is administered intravenously (IV) weekly or every three weeks at 2 or 4 mg/kg, respectively, until disease progression The antibody is supplied as a multi-dose liquid formulation (20mL fill at a concentration of 20mg/mL or higher concentration) Examples of drugs that can be combined with the antι-ErbB2 antibody (which blocks ligand activation of an ErbB 2 receptor) to treat prostate cancer (e g androgen independent prostate cancer) include a farnesyl transferase inhibitor, an anti-angiogenic agent (e g an anti-VEGF antibody), an EGFR-targeted drug (e g C225 or ZD1839), another antι-ErbB2 antibody (e g a growth inhibitory antι-ErbB2 antibody such as HERCEPTIN®, or an anti ErbB2 antibody which induces apoptosis such as 7C2 or 7F3, including humanized and/or affinity matured variants thereof), a cytokine (e g IL-2, IL-12, G-CSF or GM-CSF), an anti-androgen (such as flutamide or cyproterone acetate), leupro de, suramin, a chemotherapeutic agent such as vinblastine, estramustine, mitoxantrone, harozole (a retinoic acid metabolism-blocking agent), cyclophosphamide, anthracychne antibiotics such as doxorubicin, a taxane (e g paclitaxel or docetaxel), or methotrexate, or any combination of the above, such as vinblastine/estramustine or cyclophosphamide/doxorubicin/methotrexate, prednisone, hydrocortizone, or combinations thereof Standard doses for these various drugs can be administered, e g 40 mg/m 2 /wk docetaxel (TAXOTERE®), 6 (AUC) carboplatin, and 200mg/m 2 paclitaxel (TAXOL®)

Claims: What is claimed is I A method of treating prostate cancer in a human comprising administering to the human a therapeutically effective amount of an antibody which binds ErbB2 and blocks ligand activation of an ErbB receptor 2 The method of claim 1 wherein the prostate cancer is androgen independent prostate cancer 3 The method of claim 1 wherein the antibody blocks binding of monoclonal antibody 2C4 to ErbB2 4 The method of claim 1 wherein the antibody blocks TGF-α activation of mitogen-activated protein kinase (MAPK) 5 The method of claim 1 wherein the antibody has a biological characteristic of monoclonal antibody 2C4 6 The method of claim 5 wherein the antibody comprises monoclonal antibody 2C4 or humanized 2C4 7 The method of claim 1 wherein the antibody is an antibody fragment 8 The method of claim 7 wherein the antibody fragment is a Fab fragment 9 The method of claim 1 wherein the antibody is not conjugated with a cytotoxic agent 10 The method of claim 7 wherein the antibody fragment is not conjugated with a cytotoxic agent I I The method of claim 1 wherein the antibody is conjugated with a cytotoxic agent 12 A method of treating prostate cancer in a human comprising administering to the human therapeutically effective amounts of a chemotherapeutic agent and of an antibody which binds ErbB2 and blocks ligand activation of an ErbB receptor 13 The method of claim 12 wherein the chemotherapeutic agent is a taxane 14 An article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antibody which binds ErbB2 and blocks ligand activation of an ErbB receptor, and further comprising a package insert indicating that the composition can be used to treat prostate cancer 15 The article of manufacture of claim 14 wherein the prostate cancer is androgen independent prostate cancer The article of manufacture of claim 14 wherein the package insert further indicates treating the patient with a chemotherapeutic agent The article of manufacture of claim 16 wherein the chemotherapeutic agent is a taxane A method of treating androgen dependent prostate cancer in a human comprising administering to the human a therapeutically effective amount of an antibody which binds ErbB2 The method of claim 18 further comprising administering a therapeutically effective amount of a taxane to the human The method of claim 18 which results in an increased prostate specific antigen (PSA) index in the human The method of claim 18 wherein the antibody comprises monoclonal antibody 4D5 or humanized 4D5 The method of claim 18 wherein the antibody comprises monoclonal antibody 2C4 or humanized 2C4 An article of manufacture comprising a container and a composition contained therein, wherein the composition comprises an antibody which binds ErbB2, and further comprising a package insert indicating that the composition can be used to treat androgen dependent prostate cancer

Inventors: AGUS DAVID B, SCHER HOWARD I, SLIWKOWSKI MARK X, AGUS, DAVID, B., SCHER, HOWARD, I., SLIWKOWSKI, MARK, X.
Applicants: GENENTECH INC, SLOAN KETTERING INST CANCER, GENENTECH, INC., SLOAN-KETTERING INSTITUTE FOR CANCER RESEARCH
Application year: 2000
Main classification: A61K39
IPC codes: A61K31, A61K39, A61K47, A61P35, C07K16