Aranesp (darbepoetin alfa) Safety

Oncologic Drugs Advisory Committee

4 May 2004

Submitted: 31 March 2004

Amgen Inc.\
One Amgen Center Drive\
Thousand Oaks‚ CA 91320-1799

Table of Contents

[1 EXECUTIVE SUMMARY 7](#executive-summary)

[2 BACKGROUND 10](#background)

[2.1 Epoetin Therapeutics 10](#epoetin-therapeutics)

[2.2 Epoetin alfa and Epoetin beta: Recent Analyses
10](#epoetin-alfa-and-epoetin-beta-recent-analyses)

[2.3 Clinical Syndromes Associated with Increased EPO Levels
11](#clinical-syndromes-associated-with-increased-epo-levels)

[2.4 Framework for Safety Analyses 12](#framework-for-safety-analyses)

[3 ARANESP PROPERTIES 14](#aranesp-properties)

[3.1 Erythropoietic Protein Super-Family
14](#erythropoietic-protein-super-family)

[3.2 Aranesp is a Distinct Molecular Entity
14](#aranesp-is-a-distinct-molecular-entity)

[3.3 Aranesp Receptor Binding 14](#aranesp-receptor-binding)

[3.4 Aranesp Signaling 15](#aranesp-signaling)

[3.5 EPO-R Expression and Tumor Biology Considerations
16](#epo-r-expression-and-tumor-biology-considerations)

[4 ARANESP PRECLINICAL OBSERVATIONS
18](#aranesp-preclinical-observations)

[4.1 Aranesp Pharmacokinetics and Pharmacodynamics
18](#aranesp-pharmacokinetics-and-pharmacodynamics)

[4.2 Genotoxicity and Mutagenesis 18](#genotoxicity-and-mutagenesis)

[4.3 Human Tissue Binding 18](#human-tissue-binding)

[4.4 Thrombotic Events 18](#thrombotic-events)

[4.5 Tumor Initiation and Tumor Progression
18](#tumor-initiation-and-tumor-progression)

[5 ARANESP CLINICAL EXPERIENCE 20](#aranesp-clinical-experience)

[6 Thrombotic Events 21](#thrombotic-events-1)

[6.1 Literature Review 21](#literature-review)

[6.2 Background Epidemiology 22](#background-epidemiology)

[6.3 Aranesp Clinical Trial Experience
24](#aranesp-clinical-trial-experience)

[6.4 Proactive Aranesp Labeling 25](#proactive-aranesp-labeling)

[7 PROGRESSION-FREE SURVIVAL AND OVERALL Survival
27](#progression-free-survival-and-overall-survival)

[7.1 Individual Double-blind, Placebo-controlled Trials
28](#individual-double-blind-placebo-controlled-trials)

[7.1.1 Study 980297 28](#study-980297)

[7.1.2 Study 20000161 32](#study-20000161)

[7.2 Pooled Randomized, Double-blind, Placebo-controlled Trials
37](#pooled-randomized-double-blind-placebo-controlled-trials)

[7.2.1 Study 980291 38](#study-980291)

[7.2.2 Study 990114 39](#study-990114)

[7.2.3 Pooled Analyses 39](#pooled-analyses)

[7.3 Relationship Between Hemoglobin Metrics and Survival
41](#relationship-between-hemoglobin-metrics-and-survival)

[7.4 Tumor Types 44](#tumor-types)

[7.5 Summary of Aranesp Clinical Trial Findings
46](#summary-of-aranesp-clinical-trial-findings)

[8 OVERALL BENEFIT/RISK ASSESSMENT 47](#overall-benefitrisk-assessment)

[9 Ongoing Studies and Pharmacovigilance Program
48](#ongoing-studies-and-pharmacovigilance-program)

[9.1 Pharmacovigilance Program Analyses
51](#pharmacovigilance-program-analyses)

[9.2 Amgen Study 20010145: Study in Small-cell Lung Cancer
52](#amgen-study-20010145-study-in-small-cell-lung-cancer)

[9.3 Study FR-2003-3005: Study in Diffuse Large B-cell Lymphoma
52](#study-fr-2003-3005-study-in-diffuse-large-b-cell-lymphoma)

[9.4 Study SE-2002-9001: Study in Head-and-Neck Cancer
53](#study-se-2002-9001-study-in-head-and-neck-cancer)

[9.5 Study DE-2001-0033: Study in Neoadjuvant Breast Cancer
53](#study-de-2001-0033-study-in-neoadjuvant-breast-cancer)

[9.6 Study DE-2002-0015: Study in Adjuvant Breast Cancer
54](#study-de-2002-0015-study-in-adjuvant-breast-cancer)

[10 SUMMARY 55](#summary)

[11 REFERENCES 58](#references)

List of Tables

[Table 1. Thrombotic Event Risk Pooled Trials
24](#__RefHeading___Toc68443239)

[Table 2. Relationship Between Thrombotic Event History and Treatment
25](#__RefHeading___Toc68443240)

[Table 3. Study 980297: Baseline Demographics
29](#__RefHeading___Toc68443241)

[Table 4. Study 20000161: Baseline Demographics
33](#__RefHeading___Toc68443242)

[Table 5. Study 980291 (Schedule 1): Baseline Demographics
38](#OLE_LINK2)

[Table 6. Study 980291 (Schedule 2): Baseline Demographics
38](#__RefHeading___Toc68443244)

[Table 7. Study 990114: Baseline Demographics
39](#__RefHeading___Toc68443245)

[Table 8. Treatment Endpoint Summaries by Study
40](#__RefHeading___Toc68443246)

[Table 9. Pooled Analysis: Cox Regression Models for
42](#__RefHeading___Toc68443247)

[Table 10. Aranesp Pharmacovigilance Program Trials: Power and
Sensitivity Calculations 50](#_Ref66945216)

[Table 11. Amgen Trials and Investigator-sponsored Trials:
Pharmacovigilance Program Patient-years 52](#__RefHeading___Toc68443249)

List of Figures

[Figure 1. Patients and Patient-years of Aranesp Therapy Over Time
20](#__RefHeading___Toc68443250)

[Figure 2. Age- and Sex-adjusted Relative Incidence of Venous Thrombotic
Events Among Cancer Chemotherapy Patients Compared With the General
Population in the General Practice Research Database
23](#__RefHeading___Toc68443251)

[Figure 3. Study 980297: Progression-free Survival (Non-small Cell Lung
Cancer) 30](#_Ref68437017)

[Figure 4. Study 980297: Progression-free Survival (Small-cell Lung
Cancer) 30](#__RefHeading___Toc68443253)

[Figure 5. Study 980297: Overall Survival (Non-small Cell Lung Cancer)
31](#__RefHeading___Toc68443254)

[Figure 6. Study 980297: Overall Survival (Small-cell Lung Cancer)
31](#_Ref68444456)

[Figure 7. Study 20000161: Progression-free Survival (Aggressive
Non-Hodgkin's Lymphoma) 34](#__RefHeading___Toc68443256)

[Figure 8. Study 20000161: Progression-free Survival (Indolent
Non-Hodgkin's Lymphoma) 34](#__RefHeading___Toc68443257)

[Figure 9. Study 20000161: Progression-free Survival (Multiple Myeloma)
35](#__RefHeading___Toc68443258)

[Figure 10. Study 20000161: Progression-free Survival (Chronic
Lymphocytic\
Leukemia) 35](#__RefHeading___Toc68443259)

[Figure 11. Study 20000161: Overall Survival (Aggressive Non-Hodgkin's\
Lymphoma) 36](#__RefHeading___Toc68443260)

[Figure 12. Study 20000161: Overall Survival (Indolent Non-Hodgkin's\
Lymphoma) 36](#__RefHeading___Toc68443261)

[Figure 13. Study 20000161: Overall Survival (Multiple Myeloma)
37](#_Ref68437138)

[Figure 14. Study 20000161: Overall Survival (Chronic Lymphocytic
Leukemia) 37](#__RefHeading___Toc68443263)

[Figure 15. Pooled Data Set: Progression-free Survival
41](#__RefHeading___Toc68443264)

[Figure 16. Pooled Data Set: Overall Survival
41](#__RefHeading___Toc68443265)

[Figure 17. Pooled Analysis: Progression-free Survival for Patients with
Baseline Hemoglobin 43](#__RefHeading___Toc68443266)

[Figure 18. Pooled Analysis: Overall Survival for Patients by Baseline
Hemoglobin 44](#__RefHeading___Toc68443267)

[Figure 19. Progression-free Survival Hazard Ratios Associated With
Aranesp\
Versus Placebo Therapy 45](#__RefHeading___Toc68443268)

[Figure 20. Overall Survival Hazard Ratios Associated With Aranesp
Versus\
Placebo Therapy 45](#__RefHeading___Toc68443269)

List of Abbreviations and Glossary

  -----------------------------------------------------------------------
  **Abbreviation or Term**       **Definition/Explanation**
  ------------------------------ ----------------------------------------
  c                              common chain

  CHOP                           chemotherapy with cyclophosphamide,
                                 doxorubicin, vincristine, and prednisone

  CI                             confidence interval

  CLL                            chronic lymphocytic leukemia

  CMF                            chemotherapy with cyclophosphamide,
                                 methotrexate, and fluorouracil

  DA                             darbepoetin alfa

  ECOG                           Eastern Cooperative Oncology Group

  EFS                            event-free survival

  EGF-R                          epidermal growth factor receptor

  EPO                            (endogenous) erythropoietin

  epoetin                        Epoetin alfa and/or Epoetin beta

  EPO-R                          erythropoietin receptor

  GM-CSF                         granulocyte-macrophage
                                 colony-stimulating factor

  GPRD                           General Practice Research Database

  HER2                           human epidermal growth receptor 2

  hgb                            hemoglobin

  HR                             hazard ratio

  IL                             interleukin

  JAK-STAT                       Janus kinase/signal transducer and
                                 activator of transcription

  Kd                             dissociation constant

  kDa                            kilodalton
  -----------------------------------------------------------------------

continued

List of Abbreviations and Glossary (continued)

  ------------------------ ----------------------------------------------
  **Abbreviation or Term** **Definition/Explanation**

  Max                      maximum

  Min                      minimum

  NCCN                     National Comprehensive Cancer Network

  NE                       not estimable

  NHDS                     National Hospital Discharge Survey

  NHL                      non-Hodgkin's lymphoma

  NSCLC                    non-small cell lung cancer

  ODAC                     Oncologic Drugs Advisory Committee

  PL                       placebo

  PY                       patient-years

  R-CHOP                   chemotherapy with rituximab and
                           cyclophosphamide, doxorubicin, vincristine,
                           and prednisone

  RFS                      relapse-free survival

  RR                       relative risk

  SCLC                     small-cell lung cancer

  VEGF                     vascular endothelial growth factor
  ------------------------ ----------------------------------------------

# EXECUTIVE SUMMARY

Aranesp (darbepoetin alfa) is a unique erythropoietic molecule that
differs from other erythropoietic-stimulating proteins with regard to
amino acid sequence, glycosylation, receptor affinity, and
pharmacokinetic/pharmacodynamic profile. It is considered distinct from
other erythropoetic molecules from scientific, clinical, legal, and
regulatory perspectives. Aranesp is licensed for the treatment of anemia
in patients with chronic renal failure and patients with non-myeloid
malignancies receiving chemotherapy. Aranesp reduces fatigue and the
need for transfusions and improves quality of life for patients with
grievous illnesses. Aranesp has a favorable benefit/risk profile for the
treatment of chemotherapy-induced anemia when used in accord with
approved product labeling and published guidelines. Amgen fully supports
hemoglobin targets and dosing adjustment regimens recommended in the
approved package insert and in the National Comprehensive Cancer Network
(NCCN) guidelines. Through December 2003, more than 427,000 patients
have received Aranesp therapy, representing more than
268,000 patient-years of experience.

As the company that was first to clone erythropoietin (EPO) and was the
original developer of Epoetin alfa and the creator, developer, and
marketer of darbepoetin alfa, Amgen's central mission is to improve
patients' lives while sustaining patient safety. No signal suggesting
tumor progression or survival impairment has been observed in
preclinical or clinical studies with Aranesp. In this document, we show
that no findings from preclinical genotoxicity, mutagenicity, or chronic
toxicity studies suggest that this agent initiates tumors or promotes
tumor proliferation. In addition, we provide updated experience from
long-term follow-up in Aranesp oncology clinical trials (Hedenus et al,
2003; Vansteenkiste et al, 2002) that indicates no tumor-promoting or
detrimental effect on survival in patients with cancer.

Theoretical concerns regarding the potential for tumor progression by
erythropoietic-stimulating proteins have been present since the original
Epoetin alfa approval in 1988 for chemotherapy-induced anemia, and were
represented in the initial product labeling. Erythropoietin receptors
(EPO-R) have been reported to be present on a variety of normal
non-hematopoietic cells and tumor cells, and the functional significance
of these receptors remains the subject of ongoing investigation. The
clinical relevance of EPO-R expression on different tumor types remains
uncertain. Epoetins do not cause increased proliferation of most tumor
cell lines in vitro, even at supra-pharmacologic doses. More
importantly, no evidence exists that treatment with
erythropoietic-stimulating proteins, including Aranesp, increases tumor
progression or decreases survival in tumor xenograft models. Epoetin
receptors are not amplified or overexpressed in tumor cells, unlike
other receptors that are clearly associated with tumor growth, including
epidermal growth factor receptor (EGF-R) and human epidermal growth
receptor 2 (HER2).

The 2 controlled trials published by Leyland-Jones et al (INT-76;
Leyland-Jones, 2003) and Henke and colleagues (ENHANCE; Henke et al,
2003) were performed with Epoetin alfa (Eprex) and Epoetin beta
(NeoRecormon), and resulted in safety observations that have led to the
current review. These studies had significant design and conduct
challenges that limit interpretation of their findings (Blumberg and
Heal, 2004; Freidlin and Korn, 2004; Haddad and Posner, 2004; Kaanders
and van der Kogel, 2004; Leyland-Jones and Mahmud, 2004). Reduced
survival or increased tumor progression have not been observed in
association with Aranesp therapy.

These studies have raised many unanswered questions: Is any
erythropoietic-stimulating protein (at approved doses for approved
indications) associated with a deleterious effect on survival in
patients with cancer? Are there, in fact, safety profile differences
between the different erythropoietic-stimulating proteins? If impaired
survival is attributable to any erythropoietic therapies, what are the
relative contributions of thrombotic events, tumor progression, and
other adverse events; and are these events related to pretreatment
hemoglobin or target hemoglobin concentration, hemoglobin rate of rise,
dosing frequency, maximum concentration of or exposure to the
erythropoietic agent, associated chemoradiotherapy regimens, cancer type
or stage, or specific type of erythropoietic agent administered?

Amgen has been proactive in addressing safety concerns through product
labeling, responsible clinical trial design, and active
pharmacovigilance. Summarized in this document are analyses of more than
1100 patients receiving Aranesp therapy from 4 randomized, double-blind,
placebo-controlled trials. These analyses reveal a stable rate of
thrombotic events as expressed in the product label and reveal no
evidence for increased tumor progression or reduced survival among
patients receiving Aranesp.

Amgen has initiated the Aranesp Pharmacovigilance Program that includes
a large, randomized, controlled study in patients with small-cell lung
cancer receiving placebo or Aranesp in which survival is the primary
outcome measure. An early interim analysis has been incorporated into
this study to strengthen patient safety monitoring. In addition, Amgen
is collaborating with oncologists conducting large
investigator-sponsored trials evaluating survival outcomes in multiple
oncology patient populations, including patients with lymphoma, patients
with head-and-neck malignancies receiving radiotherapy, and 2 studies in
patients with breast cancer.

Amgen believes that full disclosure and publication of trial details is
warranted for the INT-76 trial and the ENHANCE trial in order that a
more complete understanding of the results of these trials can be
achieved. Amgen believes that erythropoietic treatment of non-anemic
patients or treatment regimens with higher-than-approved target
hemoglobin concentrations should be performed only in the setting of
well-designed and well‑executed clinical trials with careful safety
monitoring and sufficient patient numbers to permit meaningful safety
assessments.

Amgen respects the prudence of the FDA and the Oncologic Drugs Advisory
Committee (ODAC) in looking across erythropoietic therapies. At present,
no evidence suggests that Aranesp is associated with impaired survival
in patients with cancer. Amgen believes that the current Aranesp
prescribing information accurately reflects the experience with this
product and is committed to ongoing studies that will provide additional
insights. Product-specific risk assessment should be evidence-based and
driven, in large part, by product-specific observations.

Amgen is pleased to be able to share observations with the FDA and ODAC
from both preclinical and clinical Aranesp experience and welcomes the
opportunity to engage the committee to frame hypotheses for future
investigation.

# BACKGROUND

## Epoetin Therapeutics

Amgen was the first to clone Epoetin alfa and is the sponsor of the
Epoetin alfa Biologics License Application. In the United States,
Epoetin alfa is marketed under the trade names Epogen and Procrit. Amgen
clinically develops, markets, and distributes Epogen, which is indicated
for the treatment of anemia associated with chronic renal failure,
including patients who are receiving dialysis. Ortho Biotech Products,
L.P., a subsidiary of Johnson & Johnson, is responsible for the clinical
development, marketing, and distribution of Procrit in the United States
under license from Amgen. Amgen manufactures both Procrit and Epogen.
Procrit is approved for a number of indications, including the treatment
of anemia in patients with non-myeloid malignancies where anemia is due
to the effect of chemotherapy. Amgen also created and developed
Aranesp(darbepoetin alfa), which is approved in many parts of the world
for patients with non-myeloid malignancies who have chemotherapy-induced
anemia, and for patients with anemia of chronic renal disease.

Epogen/Procrit is distinct from EPREX, which is another Epoetin alfa
manufactured by Johnson & Johnson and marketed in Europe, Australia, and
Canada by Johnson & Johnson subsidiaries. Eprex is indicated for
patients with the anemia of chronic renal disease and
chemotherapy-induced anemia in patients with non-myeloid malignancies.
Eprex is the medication that was employed in the INT-76 (BEST) trial
described by Leyland-Jones (2003). Epoetin beta (NeoRecormon) is
manufactured by Roche and marketed outside the United States.
NeoRecormon is the medication that was employed in the ENHANCE trial in
head-and-neck cancer described by Henke et al (2003).

## Epoetin alfa and Epoetin beta: Recent Analyses 

The recent INT-76 and ENHANCE studies have been extensively discussed
(Blumberg and Heal, 2004; Freidlin and Korn, 2004; Haddad and Posner,
2004; Kaanders and van der Kogel, 2004; Leyland-Jones and Mahmud, 2004),
and Amgen will defer to the sponsors responsible for those studies to
represent their experience. These studies employed treatment regimens
that were outside the currently-approved labeling and guidelines. The
results from these studies are not in keeping with previous epoetin
oncology studies that have examined survival outcomes, and such findings
have not been observed with Aranesp therapy.

Bohlius and colleagues from the Cochrane Hematological Malignancies
Group (Bohlius et al, 2003) presented a comprehensive meta-analysis of
randomized, controlled oncology trials examining the effects of epoetin
therapy on tumor response and survival. The studies chosen were required
to meet the following criteria: malignancy diagnosed by histologic or
cytologic criteria; anemia or risk for anemia from chemotherapy,
radiotherapy, or underlying malignancy; therapy with Epoetin alfa or
Epoetin beta versus placebo or no additional therapy; red blood cell
transfusions as necessary in both epoetin and placebo groups;
conventional-dose cancer therapy in both epoetin and placebo groups;
randomization with or without blinding; and a minimum of 10 patients per
study group. Outcomes included overall survival and tumor response.

The Cochrane Group's search yielded 27 published studies with
3284 patients. The meta-analysis reveals no effect with regard to tumor
response (relative risk \[RR\] = 1.4 \[95% CI: 1.1, 1.7\], 7 evaluable
studies, n = 1150) and a trend toward favorable epoetin effect with
regard to overall survival (hazard ratio \[HR\] = 0.80 \[95% CI: 0.65,
1.00\], 8 evaluable trials, n = 1624). The authors conclude that more
clinical trials are needed to test the hypothesis that erythropoietic
therapies may improve overall survival.

## Clinical Syndromes Associated with Increased EPO Levels

Clinical syndromes of altered human EPO physiology may provide insights
into the potential role of erythropoietic-stimulating proteins in tumor
initiation. Primary congenital disorders associated with increased EPO
production, or mutations in the EPO-R leading to EPO hypersensitivity,
are associated with erythrocytosis in humans. Prchal and Sokol (1996)
have written a comprehensive review of primary familial and congenital
polycythemias, including EPO overexpression and EPO-R mutations, in
approximately 100 individuals in several families. In these families, no
increased cancer incidence or leukemic transformation has been observed.
A more recent publication further explored the genotype and phenotype of
individuals with Chuvash polycythemias (Prchal, 2003). These patients
have high EPO levels and polycythemia as a result of altered regulation
of the HIF-1 protein. Affected individuals develop peripheral vein
varicosities, hypertension, an increased incidence of strokes, and
increased serum levels of vascular endothelial growth factor (VEGF).
These patients do not have an increased incidence of cancer, suggesting
that increased EPO concentrations alone are not causally associated with
tumors (Pastore et al, 2003).

## Framework for Safety Analyses

In approaching the safety signals that have emerged from the INT-76 and
ENHANCE trials, 3 distinct safety outcomes are under review: survival,
tumor progression, and thrombotic events. Most observers agree that
additional preclinical studies with cells in culture or with animals may
be of interest but are unlikely to be conclusive in clarifying the
clinical impact of erythropoietic-stimulating protein therapies in
oncology patients. Discussions with investigators and regulatory
authorities have been useful in framing oncology study design elements
required to evaluate survival and tumor progression outcomes. These
elements include a patient population with uniform tumor type,
randomization of patients to erythropoietic-stimulating protein therapy
versus control therapy, prospective design, stratification of important
prognostic features for the type of tumor being studied, and sufficient
size to permit detection of small differences in safety signals.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Amgen originally cloned and developed Epoetin alfa (Procrit,      |
|     Epogen) and created and developed darbepoetin alfa (Aranesp).     |
+-----------------------------------------------------------------------+
| -   A recent meta-analysis of oncology trials has shown no signal for |
|     decreased tumor responses or reduced survival.                    |
+-----------------------------------------------------------------------+
| -   The clinical trials that have raised concerns over tumor          |
|     progression and survival have been performed with Epoetin alfa    |
|     and Epoetin beta. Such findings have not been observed with       |
|     Aranesp and, thus, do not constitute a class effect.              |
+-----------------------------------------------------------------------+
| -   Well-designed, prospective, randomized, controlled clinical       |
|     trials with oncology patient populations that have the same tumor |
|     type, and stratification by prognostic factors, are required to   |
|     evaluate tumor progression and survival signals.                  |
+-----------------------------------------------------------------------+

#  ARANESP PROPERTIES

## Erythropoietic Protein Super-Family

The nucleotide and amino acid sequence of human EPO was first determined
in 1983 (Lin et al, 1985), and several epoetin molecules subsequently
were developed and approved for clinical use (Epoetin alfa, Epoetin
beta, and Epoetin omega). These epoetins have in common the same amino
acid sequence and similar, if not identical, physicochemical properties,
EPO-R affinities, half-lives, and pharmacologic effects. Although
manufacturing differences can substantially alter product quality and
immunogenicity, the fundamental biologic and physicochemical properties
of each epoetin molecule are dictated in large part by the common amino
acid sequence.

## Aranesp is a Distinct Molecular Entity

Aranesp represents a significant advance in the development of
erythropoietic-stimulating protein therapy. Amgen engineered more than
450 epoetin glycosylation analogs containing altered amino acid
sequences, and each of the molecules was evaluated for structural
stability, biologic activity, and half-life. Five amino acid changes
were combined into 1 distinct molecule to enable the addition of 2 new
carbohydrate chains at unique sites on the protein backbone. The
resulting molecule is distinct from epoetin with regard to physical
size, proportion of molecular weight as carbohydrate, number of sialic
acid moieties, and amino acid sequence. It has a longer terminal
half‑life (25.3 hours vs 8.5 observed with Epoetin alfa \[Macdougall et
al, 1999\]), an approximately 5-fold reduction in EPO-R affinity, and a
higher concentration is required to activate multiple in vitro assays
(12-fold increase required for half-maximal activity in assays of
hematopoietic cell growth \[Amgen, data on file\]. Therefore, Aranesp is
considered a distinct molecular entity from scientific (Egrie et al,
2003; Elliott et al, 2003), clinical (Macdougall et al, 1999), legal,
and regulatory perspectives.

## Aranesp Receptor Binding

A higher Aranesp concentration is required to achieve maximal
intracellular signaling in hematopoietic cells compared with epoetins.
Similarly, the threshold concentration for activation of erythropoiesis
in vitro is higher for Aranesp than for epoetins. The reduction in in
vitro activity is likely because the EPO-R:epoetin-binding interface
involves positive charges on epoetins and negative charges on the
receptor (Syed et al, 1998; Elliott et al, 1997). This finding is
consistent with the observation that sialic acid (a negatively charged
sugar) reduces the on-rate of Aranesp binding to EPO-R through
electrostatic charge shield effects (Darling et al, 2002). The lower
receptor-binding affinity is associated with significant biologic
activity in part due to the longer Aranesp half-life in vivo (Egrie et
al, 2003).

## Aranesp Signaling

Aranesp works through interaction with EPO-R to promote proliferation,
survival, and differentiation of hematopoietic cells in a manner
consistent with the activity of endogenous EPO. It is not known whether
Aranesp binding to EPO-R in other tissues results in different
intracellular signaling from that observed with epoetins.

EPO-R proteins involved in hematopoiesis exist on the cell surface
(Livnah et al, 1999; Remy et al, 1999) and activation occurs when 1
erythropoietic-stimulating protein binds 2 EPO-R molecules (Syed et al,
1998; Youssoufian et al, 1993). EPO-R signaling in hematopoietic cells
predominately occurs though phosphorylation of JAK2, and subsequent
activation of STAT5, PI3 kinase, and MAP kinase pathways. These and
possibly other pathways are believed to produce the downstream effects
of cellular proliferation, survival (anti-apoptosis), and
differentiation although the criticality and redundancy of these and
other intracellular pathways are still the subject of research. Although
some of these pathways appear to be active in non-hematopoietic and
tumor cell lines, other pathways have been identified as well, and it is
unclear if these pathways lead to the proliferative effects or survival
effects observed in hematopoietic cells.

Other components in addition to EPO-R may contribute to signaling in
different non‑hematopoietic cell types. The GM-CSF/IL-3/IL-5 receptor
-common chain (c) has been found to associate with EPO-R (Jubinsky et
al, 1997) and erythropoietic-stimulating proteins induce modification of
the c (Chin et al, 1997), which, in turn, promotes modification of EPO-R
(Blake et al, 2002). Data suggest that EPO-R may also interact with the
receptor for another regulatory molecule, stem cell factor (Wu et al,
1997; Wu et al, 1995). These interactions suggest functional "cross
talk" between receptors and receptor complexes that contain EPO-R, and
accessory receptors may affect epoetin downstream signaling differently
in different cell types.

The relationships among receptor affinity, receptor number, tissue
specificity, potential accessory molecules, receptor cross-talk, and
signal transduction are not fully understood, particularly in the
context of non-hematopoietic cell types. The down-stream consequences of
signaling by EPO through EPO-R in non-hematopoietic cells in vivo likely
further alters the relationship between these variables and biologic
response. It is inappropriate to assume that different
erythropoietic-stimulating proteins with different amino acid sequences
and different receptor affinities have similar biologic effects on all
cell types.

## EPO-R Expression and Tumor Biology Considerations

Based on EPO-R detection on tumors and the biologic functions of EPO,
concerns have been raised regarding a potential role for
erythropoietic-stimulating proteins in tumor progression. The role of
erythropoietic-stimulating proteins and EPO-R in hematopoietic cell
differentiation and survival is well defined. Erythropoietic-stimulating
proteins, including darbepoetin alfa, work through interaction with
EPO-R to normally promote the differentiation, proliferation, and
survival of hematopoietic cells. EPO-R appears to be expressed on a wide
range of normal non-hematopoietic tissues and malignancies, although its
role in these tissues is less understood. In most cases where EPO-R has
been detected on malignant tissue, EPO-R has been found on the tissue of
origin as well. Although EPO-R can be detected by multiple methods,
expression may not correspond with function.

In tumors, expression of known oncogenic growth factor receptors, such
as EGF-R and HER2, can be increased as much as a 100-fold over normal
cells. EGF-R and HER2 receptor overexpression is clearly associated with
clinical outcomes. In contrast, tumor cell lines do not appear to have
increased numbers of EPO-R on their surface. Where EPO-R affinity has
been measured, major differences in receptor affinity on hematopoietic,
non-hematopoietic, and tumor cell lines are not apparent.

The effect of epoetin in tumor cell line proliferation has been
investigated in cell culture studies. In 5 published studies, with \> 50
tumor cell lines, epoetin did not increase tumor cell proliferation even
at supra-pharmacologic doses (Westphal et al, 2002; Rosti et al, 1993;
Berdel et al, 1992; Mundt et al, 1992; Berdel et al, 1991). In the
3 studies in which epoetin appears to have increased tumor cell
proliferation in vitro, epoetin exposure was associated with only a
marginal proliferative signal (Acs et al, 2001; Takeshita et al, 2000;
Westenfelder and Baranowski, 2000). Amgen is not aware that such studies
have been performed with Aranesp.

In summary, the evidence that EPO-R and erythropoietic-stimulating
proteins play a significant role in tumor progression is weak, and there
is no evidence that Aranesp has a role in tumor initiation or
progression.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Aranesp is considered a distinct molecular entity from            |
|     scientific, clinical, legal, and regulatory perspectives.         |
+-----------------------------------------------------------------------+
| -   There is no evidence that Aranesp promotes tumor progression in   |
|     preclinical studies.                                              |
+-----------------------------------------------------------------------+
| -   EPO-R detection on non-hematopoietic cells and tumor cells does   |
|     not correlate well with EPO-R function.                           |
+-----------------------------------------------------------------------+
| -   The observation that EPO-R is detected on tumor cell lines and    |
|     tissues does not mean that erythropoietic-stimulating proteins    |
|     are drivers for tumor progression.                                |
+-----------------------------------------------------------------------+
| -   EPO-R is expressed at similar levels and affinity in malignant    |
|     tissues and in normal non-hematopoietic tissue of origin.         |
+-----------------------------------------------------------------------+
| -   EPO-R is not an established oncogene like HER2 or EGF-R.          |
+-----------------------------------------------------------------------+

#  ARANESP PRECLINICAL OBSERVATIONS

## Aranesp Pharmacokinetics and Pharmacodynamics

The pharmacokinetic and pharmacodynamic properties of Aranesp and
epoetin have been determined in a range of animal species. The data
consistently indicate that Aranesp is cleared more slowly (generally
3-fold) than epoetin, has a similar volume of distribution (slightly
larger than plasma volume), and has a longer terminal half-life
(approximately 3-fold longer) (Egrie et al, 2003).

## Genotoxicity and Mutagenesis

Aranesp is not mutagenic or genotoxic. It produces negative results in
the bacterial reverse mutation assay, the Chinese hamster ovary cell
gene mutation assay, and the mouse bone marrow micronucleus assay.

## Human Tissue Binding

In a tissue-binding study performed with Aranesp and a panel of 23
normal human tissues, bone marrow was the only tissue that demonstrated
Aranesp binding. These findings suggest that other tissues do not
express EPO-R at sufficient density or affinity to result in detectable
Aranesp binding.

## Thrombotic Events

Preclinical studies with rats, dogs, and monkeys have been performed to
evaluate the relationship between thrombus formation and exposure to
epoetin and Aranesp. Studies performed with rats and dogs treated with
Aranesp for up to 6 months and a single-dose study in monkeys examined
toxicities related to hemoglobin rate of rise and sustained high
hematocrit. Animals were treated with supra-pharmacologic doses (up to
100 µg/kg \[rats\] or 50 µg/kg \[dogs\]) of Aranesp 3 times per week).
These treatment schedules resulted in rates of hemoglobin rise that were
at least 2.5 times greater than the rate recommended in the approved
prescribing information for patients. This rapid rate of hemoglobin rise
was not associated with mortality or other adverse events. As expected,
thrombotic events were noted when hemoglobin levels were sustained above
physiologic levels.

## Tumor Initiation and Tumor Progression

Several toxicology studies have been conducted in rats and dogs with
supra‑pharmacologic doses of Aranesp, all of which included extensive
histologic investigations. Examination of numerous tissue types,
including those commonly associated with spontaneous or inducible
cancers, revealed no evidence of abnormal mitogenic or tumorigenic
responses. With the exception of tissue changes normally associated with
the pharmacologic effect of Aranesp (ie, Kupffer cell hyperplasia
associated with removal of degenerated erythrocytes), no evidence of
hyperplasia, proliferation, abnormal tissue architecture, or increased
tissue mitotic indices were observed. The long-term toxicology studies
(up to 6 months) in which normal animals were exposed to very high
levels of Aranesp provide preclinical evidence that chronic exposure to
Aranesp is not associated with tumorigenesis.

Two studies have evaluated the impact of Aranesp in rodent tumor
xenograft models (Kirkpatrick et al, 2003; Ning and Knox, 2004). Ning
and Knox administered 30 µg/kg Aranesp every 1 or 2 weeks after
induction of anemia by total body irradiation in tumor-bearing mice.
Aranesp effectively corrected anemia, increased tumor oxygenation, and
increased the radiosensitivity of established squamous cell carcinoma
and fibrosarcoma to fractionated radiotherapy. The authors also reported
a significant radiosensitivity increase in Aranesp-treated animals
before anemia correction was evident and these beneficial effects of
Aranesp occurred in a dose-dependent manner. In non-anemic rats bearing
R3230 mammary carcinoma xenografts, administration of Aranesp at 3 g/kg
subcutaneously 3 times per week for 18 days significantly increased
oxygen tension in the tumor but did not alter tumor growth or increase
tumor response to radiation therapy (Kirkpatrick et al, 2003). This
tumor cell line is known to express EPO-R as assessed by Western
blotting (Arcasoy et al, 2002) and Aranesp exposure did not lead to
increased tumor growth.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   There is no evidence from preclinical studies that Aranesp        |
|     initiates tumors or promotes more rapid growth of pre-existing    |
|     tumors.                                                           |
+-----------------------------------------------------------------------+
| -   In some animal studies, Aranesp appears to increase the           |
|     beneficial effects of radiotherapy.                               |
+-----------------------------------------------------------------------+

# ARANESP CLINICAL EXPERIENCE

Through December 2003, more than 427,000 patients have received Aranesp
therapy, representing more than 268,000  patient-years of experience
(Figure 1). Oncology patients represent a substantial proportion of this
experience, and constitute 133,000 patients and 65,000 patient-years.
The Aranesp clinical trial database for Amgen-sponsored trials through
December 2003 includes more than 20,000 patients and represents more
than 9700 patient-years of experience.

[]{#__RefHeading___Toc68443250 .anchor}Figure 1. Patients and
Patient-years of Aranesp Therapy Over Time

![](media/image2.wmf){width="4.126388888888889in"
height="3.7916666666666665in"}

> Amgen, data on file.

The efficacy of Aranesp at the licensed dose (2.25 µg/kg weekly) and the
commonly used dosing regimen in the United States \[200 µg every other
week\] has been well established (Hedenus et al, 2003; Schwartzberg et
al, 2003; Vadhan Raj et al, 2003; Vansteenkiste et al, 2002).
Significant reductions in transfusion requirements, and improvements in
patients reporting fatigue have been demonstrated with both dosing
regimens. In general, more than 70% of anemic cancer patients achieve
the target hemoglobin range of 11 to 12 g/dL specified by the NCCN
anemia guidelines (NCCN, 2003). In these clinical trials, subsequent
maintenance of hemoglobin at approximately 12 g/dL on average was
observed (Schwartzberg et al 2003; Amgen, data on file).

# Thrombotic Events

An association between Aranesp therapy and thrombotic events was
described in the original licensing application and proactively
represented in product labeling. More recently, Amgen has performed a
comprehensive review of the medical literature regarding thrombotic
events in malignancy, and performed multiple epidemiologic analyses to
evaluate the background incidence rates of thrombotic events in patients
with cancer. An analysis also has been updated regarding thrombotic
event rates and risk factors from pooled Aranesp oncology trials, which
includes studies performed before and after product approval.

## Literature Review

Patients with cancer are at a higher risk for thrombotic events than
individuals without cancer (Lee and Levine, 2003). The incidence of
thrombotic events in patients with cancer in modern prospective studies
has ranged from 13.1/1000 patient-years (PY) (Joung and Robinson, 2002)
to 109/1000 PY (Otten et al, 2004), and thrombotic events contribute
substantially to cancer patients' morbidity and mortality (Ambrus et al,
1975).

The etiology of thrombotic events in oncology patients is thought to be
multifactorial (Kwaan et al, 2003; Caine et al, 2002). Hypercoagulable
states, direct injury to the vascular endothelium, and inflammation may
all predispose patients with cancer to thrombotic events (Falanga and
Donati, 2001; Kakkar et al, 1995; Bevilacqua et al, 1986). Cancer type
and stage (Lee and Levine, 2003; Levitan et al, 1999), indwelling
catheters, surgery, and chemotherapy all contribute to the increased
risk of developing thrombotic events observed in cancer patients (Otten
et al, 2004; Verso and Agnelli, 2003; Heit et al, 2002; Lee and Levine,
1999; Pritchard et al, 1996; Clahsen et al, 1994; Levine et al, 1988).

A systematic review of the published literature from January 1990 to
July 2003 was performed, selecting publications pertaining to epoetin or
Aranesp in cancer anemia published in any of 5 languages (English,
French, German, Italian, or Spanish). All randomized, controlled trials
and prospective interventions were identified and examined for
thrombotic events risk factors and the calculation of thrombotic event
incidence rates. Studies that only appeared to report "drug-related"
events or appeared to selectively report safety events were not included
in statistical analyses. The review identified 63 studies that were
included in the final study set for analysis. All studies included
patients treated with epoetin, Aranesp, or iron treatment with
extractable (or logically imputable) numbers of safety events.

In this review, 70% of patients had solid tumors, 28% had hematologic
cancer, and the remaining patients had unknown/mixed tumors. In studies
reporting deep vein thrombosis as an outcome, the overall mean incidence
of deep vein thrombosis was 37/1000 PY and the incidence among patients
receiving epoetin was 46/1000 PY. The mean incidence of pulmonary
embolism was 23/1000 PY, and patients receiving epoetin treatment had a
mean incidence of 30/1000 PY. Few factors appeared to have significant
impact on the incidence rate, but data for this evaluation were limited.

## Background Epidemiology

Because of the limited information in the published literature, Amgen
investigated the incidence of thrombotic events in several primary data
analyses. The incidence in the general population was estimated using
data from the National Hospital Discharge Survey (NHDS) and the United
Kingdom General Practice Research Database (GPRD). Thrombotic event
incidence in patients with cancer who were receiving chemotherapy was
investigated using data from the GPRD and 2 large, nationwide
claims-based databases: the UnitedHealth/Ingenix database, and the
Medstat Marketscan database. The Medstat database offered the
opportunity to investigate the incidence of thrombotic events among
cancer chemotherapy patients with anemia.

The incidence rates of thrombotic events estimated in the NHDS United
States population and GPRD United Kingdom population, when standardized
to the age distribution of the Ingenix study population, were similar:
2.5/1000 PY for the NHDS (based on the 2001 United States population)
and 2.7/1000 PY for the GPRD (based on approximately 35,000,000 PY). The
incidence of thrombotic events among the cancer chemotherapy populations
was substantially increased, ranging from 13.7/1000 PY in GPRD (based on
approximately 108,000 PY) to 34.5 in Medstat (based on approximately
7000 PY) and 59.2 in Ingenix (based on approximately 4000 PY).

In the GPRD analysis, the rate of thrombotic events varied greatly by
type of cancer (Figure 2). Patients with cancer of the central nervous
system and those with metastatic disease had the highest rate of
thrombotic events and patients with breast and head-and-neck cancers had
the lowest rate. Similar trends were seen in the Medstat and Ingenix
databases, although with more variability due to the smaller number of
thrombotic events.

[]{#__RefHeading___Toc68443251 .anchor}Figure 2. Age- and Sex-adjusted
Relative Incidence of Venous Thrombotic Events Among Cancer Chemotherapy
Patients Compared With the General Population in the General Practice
Research Database

![](media/image3.wmf){width="4.7659722222222225in"
height="3.238888888888889in"}

> Low-grade lymphoma includes non-Hodgkin's lymphoma and cutaneous
> T-cell lymphoma, and high-grade lymphoma includes Hodgkin's disease,
> mantle cell, and non-cutaneous T-cell lymphoma. Metastatic tumors
> include patients who had metastases of their primary cancer. 95%
> confidence interval are shown in error bars.

The Medstat database allows for assessment of subsets of oncology
patients receiving chemotherapy. Patient subsets include those with and
without anemia, and the anemic patient subset can be further analyzed
based on exposure to erythropoietic-stimulating protein. The cutoff for
this database is 1999 and, therefore, all erythropoietic-stimulating
protein treatment represents Epoetin alfa (Procrit) exposure. When
stratifying the Medstat data by anemia, we found that anemic cancer
chemotherapy patients had a substantially higher incidence of thrombotic
events compared with patients without reports of anemia. The crude
incidence rate among those with anemia was 120/1000 PY (based upon
831 PY) while the crude rate among those without anemia was 69/1000 PY
(based upon 6013 PY), giving a crude relative hazard of 1.67 (95% CI:
1.34, 2.07). After adjusting for age, sex, cancer type, and
comorbidities, the incidence of thrombotic events in the anemic group
remained significantly increased compared with those patients without
anemia (HR = 1.35; 95% CI: 1.08, 1.68). The higher risk for thrombotic
events in anemic patients may reflect the independent association of
both anemia and thrombotic risk with underlying disease severity.

The incidence rate in anemic patients after erythropoietic-stimulating
protein exposure (176/1000 PY) also was greater than the incidence rate
in anemic patients before or without erythropoietic-stimulating protein
exposure (101/1000 PY). After adjusting for age, sex, cancer type, and
comorbidities, a similar multivariate comparison of the incidence before
or after erythropoietic-stimulating protein exposure continued to
suggest a higher rate in the erythropoietic-stimulating protein group,
but was not statistically significant (HR = 1.40, 95% CI: 0.90, 2.16).

## Aranesp Clinical Trial Experience

Thrombotic event risk was evaluated using data from 11 studies,
including all clinical development Aranesp oncology chemotherapy studies
with a final (locked) database as of November 2003. These studies
included placebo and non-placebo controls. All patients who received at
least 1 dose of study drug are included. A total of 2251 patients were
evaluated (1807 Aranesp and 444 placebo). Overall, 6% (111/1807) of
Aranesp and 3% (15/444) of placebo patients reported thrombotic events.

Patients in the Aranesp group had a higher risk of any thrombotic event
compared with patients in the placebo group (p = 0.02 by log-rank test).
Univariate analysis revealed 3 factors (Aranesp treatment, prior
thrombotic event, and poor Eastern Cooperative Oncology Group \[ECOG\]
performance status) with an unadjusted log-rank p-value \< 0.05. Sex,
age, prior cardiovascular events, race, obesity, baseline hemoglobin,
dose schedule, baseline platelet counts, platinum chemotherapy, and
baseline serum EPO concentration were not statistically associated with
thrombotic event risk.

A Cox regression analysis was performed with the 3 significant risk
factors (treatment, thrombotic event history, and ECOG performance
status) identified by univariate log-rank tests. In this multivariate
analysis, each effect remained significant predictors of thrombotic
events (Table 1).

[]{#__RefHeading___Toc68443239 .anchor}Table 1. Thrombotic Event Risk
Pooled Trials

+-----------------------------+--------------+--------------+---------+
|                             | Hazard Ratio | 95% CI       | p-value |
+-----------------------------+--------------+--------------+---------+
| History of thrombotic       | 2.70         | 1.64, 4.45   | \       |
| events                      |              |              | < 0.001 |
+-----------------------------+--------------+--------------+---------+
| Treatment                   | 1.97         | 1.15, 3.39   | 0.014   |
|                             |              |              |         |
| (Aranesp vs Placebo)        |              |              |         |
+-----------------------------+--------------+--------------+---------+
| ECOG Performance Status     | 1.64         | 1.04, 2.59   | 0.033   |
|                             |              |              |         |
| (2 or 3 vs 0 or 1)          |              |              |         |
+-----------------------------+--------------+--------------+---------+

No interactions among these variables were statistically significant at
the 0.05 level, although the number of patients with a history of
thrombotic events was low (Table 2).

[]{#__RefHeading___Toc68443240 .anchor}Table 2. Relationship Between
Thrombotic Event History and Treatment

+---------------------------------+-----------------+-----------------+
| Percentage of Patients with     | Aranesp         | Placebo         |
| On-study Thrombotic Event       |                 |                 |
|                                 | \% (n)          | \% (n)          |
+---------------------------------+-----------------+-----------------+
| No history of thrombotic event  | 6% (97/1703)    | 3% (11/412)     |
+---------------------------------+-----------------+-----------------+
| History of thrombotic event     | 13% (14/104)    | 13% (4/32)      |
+---------------------------------+-----------------+-----------------+

The effects of time-varying hemoglobin changes were examined by Cox
analyses, adjusted by the significant risk factors (treatment,
thrombotic event history, and ECOG performance status). No association
was found between thrombotic event risk and hemoglobin thresholds of 11,
12, 13, and 14 g/dL. The hazard ratio (p-values) were 1.11 (0.626), 1.34
(0.182), 1.09 (0.747), and 1.19 (0.635), respectively. No association
was observed between thrombotic event risk and increasing hemoglobin.
The hazard ratio associated with a 1-g/dL hemoglobin increase in any 14
days was 1.04; 95% CI: 0.66, 1.62; p = 0.878). While the hazard ratio
associated with a 2-g/dL hemoglobin increase in 28 days was 1.5, it was
not statistically significant (95% CI: 0.97, 2.24; p = 0.07).

## Proactive Aranesp Labeling

Amgen proactively addressed thrombotic events at the time of the
original Biologic License Supplement for the Aranesp oncology
indication, which is reflected in the warning section of the product
labeling. A comprehensive review of thrombotic events described in the
medical literature and an examination of multiple population databases
and the Aranesp clinical trials confirms the thrombotic event rates are
similar to those represented in the product label. Therefore, the low
risk of thrombotic events associated with Aranesp therapy is
appropriately reflected in current product label language and the rate
of thrombotic events has remained stable over time.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Patients with cancer have a higher background incidence of        |
|     thrombotic events than the general public.                        |
+-----------------------------------------------------------------------+
| -   Risk factors for thrombotic events include the underlying type of |
|     malignancy, stage of disease, prior thrombotic events,            |
|     performance status, and anemia.                                   |
+-----------------------------------------------------------------------+
| -   Clinical trials and epidemiologic studies show that thrombotic    |
|     events are associated with currently available                    |
|     erythropoietic-stimulating therapy.                               |
+-----------------------------------------------------------------------+
| -   Thrombotic events are appropriately addressed in the Aranesp      |
|     product label.                                                    |
+-----------------------------------------------------------------------+

# PROGRESSION-FREE SURVIVAL AND OVERALL Survival

Subsequent to the reports describing findings from the INT-76 and
ENHANCE studies, Amgen initiated a review of completed oncology clinical
trials to determine whether similar survival observations were
associated with Aranesp therapy. Studies primarily designed for the
purpose of assessing tumor outcomes and survival in oncology patients
should include the following design elements: randomized, controlled,
homogenous tumor population; stratification for predictors of tumor
response; collection of appropriate endpoint data; and adequate duration
of follow-up. Many of the Aranesp trials were not appropriate for this
kind of analysis, reflecting their focus on treatment of anemia, with
short-term endpoints related to hemoglobin level and number of
transfusions. All randomized, double-blind, placebo-controlled trials
were selected and evaluated both as individual studies and as a pooled
dataset. The analysis includes 2 trials (Studies 980297 and 20000161)
conducted in patients with lung cancer and lymphoid malignancies,
respectively, in which patients were followed after the treatment
interval to evaluate prospectively defined progression-free survival and
overall survival endpoints (Hedenus et al, 2003; Vansteenkiste et al,
2002). The same endpoints were analyzed using data from these 2 clinical
trials combined with the data from 2 smaller, dose-finding,
placebo-controlled studies (Studies 980291 and 990114) enrolling
patients with mixed tumor types and lymphoid malignancies, respectively
(Kotasek et al, 2003; Hedenus et al, 2002). Although the latter two
16-week, dose-finding studies did not contain a long-term follow-up
phase, they were included in the pooled analysis because the safety
signals observed in the INT-76 and ENHANCE trials were observed during
the initial months in those studies, and these trials allowed
comparative observation of survival over a similar time frame.

As noted, the 4 double-blind, placebo-controlled studies were designed
to study the benefits of anemia therapy in the setting of
chemotherapy-induced anemia, and therefore contain specific on-study
design features (endpoints, patient population, sample size, treatment
duration, and stratification factors) that differ from those included in
classic cancer therapeutic studies. The duration of Aranesp therapy in
all trials was at least 12 weeks, similar to the average duration of
anemia treatment for patients receiving chemotherapy of 12 to 16 weeks.
Although these studies are heterogeneous for some important factors used
to assess the benefits of oncology therapeutics, including tumor
histology, disease stage, chemotherapy treatment, method and timing of
tumor assessment, and duration of follow-up, they did have uniform
design elements (including double-blind, placebo-controlled groups),
inclusion criteria, trial endpoints, and trial methodologies. These
studies constitute an appropriate data set to evaluate progression-free
survival and overall survival outcomes. The sample size of the pooled
analysis (n = 1129) allows detection of relatively small differences in
overall mortality risk. The hazard ratio for mortality was 0.97 with a
95% confidence interval of 0.79 to 1.18.

In addition, we considered the possibility that the safety observations
from the INT-76 trial and ENHANCE trial may have been related to design
features unique to those studies, such as the inclusion of patients with
high baseline hemoglobin levels, the effect of rapid hemoglobin
increases and the inclusion of selected tumor types. Parallel analyses
of Aranesp trials were limited by the fact that Amgen trials restricted
baseline hemoglobin, hemoglobin rate of rise, and maximum hemoglobin
concentrations.

## Individual Double-blind, Placebo-controlled Trials 

###  Study 980297

Study 980297 was a multicenter, double-blind, placebo-controlled study
designed to evaluate the effects of Aranesp at a dose of 2.25 g/kg once
weekly on anemia endpoints in patients with both non-small cell lung
cancer and small-cell lung cancer receiving platinum-containing
chemotherapy (Vansteenkiste et al, 2002). A total of 314 anemic patients
(hemoglobin concentration  11 g/dL) were randomly assigned to receive
Aranesp or placebo administered weekly as a subcutaneous injection for
12 weeks, followed by a 4-week observation period. Baseline demographics
and disease characteristics were similar between treatment groups (Table
3). Subsequent to the end of the study period, patients entered a
long-term, open-label follow-up for tumor progression and survival
status. The median follow-up in this study is 16 months.

[]{#__RefHeading___Toc68443241 .anchor}Table 3. Study 980297: Baseline
Demographics

+---------------------------------------+--------------+--------------+
|                                       | Placebo      | Aranesp      |
|                                       |              |              |
|                                       | N = 159      | N = 155      |
+---------------------------------------+--------------+--------------+
| Sex (n/%)                             | 117 (74)     | 110 (71)     |
|                                       |              |              |
| Men                                   | 42 (26)      | 45 (29)      |
|                                       |              |              |
| Women                                 |              |              |
+---------------------------------------+--------------+--------------+
| Age (yr)                              | 61           | 62           |
|                                       |              |              |
| Median                                | 36 - 79      | 39 - 80      |
|                                       |              |              |
| Min - Max                             |              |              |
+---------------------------------------+--------------+--------------+
| Small-cell lung cancer (n/%)          | 45 (28)      | 47 (30)      |
|                                       |              |              |
| Limited disease^a^                    | 19 (12)      | 16 (10)      |
|                                       |              |              |
| Extensive disease^b^                  | 26 (16)      | 31 (20)      |
+---------------------------------------+--------------+--------------+
| Non-small cell lung cancer (n/%)      | 114 (72)     | 108 (70)     |
|                                       |              |              |
| Stage I                               | 2 (1)        | 2 (1)        |
|                                       |              |              |
| Stage II                              | 2 (1)        | 2 (1)        |
|                                       |              |              |
| Stage III                             | 48 (30)      | 29 (19)      |
|                                       |              |              |
| Stage IV                              | 62 (39)      | 75 (48)      |
+---------------------------------------+--------------+--------------+
| Performance status                    | 23 (14)      | 22 (14)      |
|                                       |              |              |
| 0                                     | 99 (62)      | 108 (70)     |
|                                       |              |              |
| 1                                     | 37 (23)      | 24 (15)      |
|                                       |              |              |
| 2                                     | 0            | 1 (1)        |
|                                       |              |              |
| \>2                                   |              |              |
+---------------------------------------+--------------+--------------+

> ^a^ Limited disease refers to disease within the thoracic cavity
>
> ^b^ Extensive disease refers to disease extending beyond the thoracic
> cavity
>
> Min = minimum; Max = maximum

Three hundred and fourteen patients were treated (155 receiving Aranesp
and 159 receiving placebo). Overall survival and progression-free
survival for the non‑small cell lung cancer and small-cell lung cancer
histologies is shown in Figure 3 to Figure 6. No statistically
significant differences between groups were seen at the 0.05 level when
examining the individual tumor histologies or the overall groups.

[]{#_Ref68437017 .anchor}

Figure 3. Study 980297: Progression-free Survival\
(Non-small Cell Lung Cancer)

![](media/image4.wmf){width="6.079861111111111in" height="2.5875in"}

[]{#__RefHeading___Toc68443253 .anchor}Figure 4. Study 980297:
Progression-free Survival\
(Small-cell Lung Cancer)

![](media/image5.wmf){width="6.069444444444445in"
height="2.5722222222222224in"}

[]{#__RefHeading___Toc68443254 .anchor}Figure 5. Study 980297: Overall
Survival\
(Non-small Cell Lung Cancer)

![](media/image6.wmf){width="6.079861111111111in"
height="2.6770833333333335in"}

[]{#_Ref68444456 .anchor}Figure 6. Study 980297: Overall Survival\
(Small-cell Lung Cancer)

![](media/image7.wmf){width="6.25in" height="2.654861111111111in"}

###  Study 20000161

In Study 20000161 (Hedenus et al, 2003), a randomized, double-blind,
placebo-controlled study, 344 anemic patients (hemoglobin concentration
 11 g/dL) with lymphoid malignancies and chemotherapy-induced anemia
received Aranesp 2.25 g/kg once weekly or placebo as a subcutaneous
injection for 12 weeks followed by a 4-week observation period. No
restrictions on prior chemotherapy were included in this study, and
patients were allowed to enter the study at any point during their
course of therapy. Baseline demographics and disease characteristics in
general were similar between treatment groups; however, in some tumor
subsets, such as chronic lymphocytic leukemia, some imbalances were
seen, such as more patients with indolent lymphoma being randomly
assigned to placebo and more patients with a higher stage of disease
being randomly assigned to treatment with Aranesp (Table 4). Subsequent
to the end of the study period, patients entered a long-term, open-label
follow-up for tumor progression and survival status. The median
follow-up is 27 months.

[]{#__RefHeading___Toc68443242 .anchor}Table 4. Study 20000161: Baseline
Demographics

+--------------------------------------+---------------+---------------+
|                                      | Placebo       | Aranesp       |
|                                      |               |               |
|                                      | N = 169       | N = 175       |
+--------------------------------------+---------------+---------------+
| Sex (n/%)                            | 78 (46)       | 87(50)        |
|                                      |               |               |
| Men                                  | 91 (54)       | 88 (50)       |
|                                      |               |               |
| Women                                |               |               |
+--------------------------------------+---------------+---------------+
| Age (yr)                             | 67            | 68            |
|                                      |               |               |
| Median                               | 18 -87        | 20 - 86       |
|                                      |               |               |
| Min - Max                            |               |               |
+--------------------------------------+---------------+---------------+
| Hodgkin's disease (n/%)              | 9 (5)         | 12 (7)        |
+--------------------------------------+---------------+---------------+
| Non-Hodgkin's lymphoma (n/%)         | 45 (27)       | 39 (22)       |
|                                      |               |               |
| Indolent                             | 29 (64)       | 20 (51)       |
|                                      |               |               |
| Aggressive                           | 16 (36)       | 17 (44)       |
+--------------------------------------+---------------+---------------+
| Multiple myeloma^a^ (n/%)            | 83 (49)       | 90 (51)       |
|                                      |               |               |
| Stage I                              | 5 (3)         | 15 (9)        |
|                                      |               |               |
| Stage II                             | 23 (14)       | 21 (12)       |
|                                      |               |               |
| Stage IIIA                           | 50 (30)       | 52 (30)       |
|                                      |               |               |
| Stage IIIB                           | 5 (3)         | 2 (1)         |
+--------------------------------------+---------------+---------------+
| Chronic lymphocytic leukemia^b^      | 26 (15)       | 29 (17)       |
| (n/%)                                |               |               |
|                                      | 7 (4)         | 5 (3)         |
| Stage A                              |               |               |
|                                      | 7 (4)         | 6 (3)         |
| Stage B                              |               |               |
|                                      | 11 (7)        | 17 (10)       |
| Stage C                              |               |               |
+--------------------------------------+---------------+---------------+
| Waldenstrom's macroglobulinaemia     | 6 (4)         | 5 (3)         |
| (n/%)                                |               |               |
+--------------------------------------+---------------+---------------+

> ^a^ Durie and Salmon staging system of multiple myeloma
>
> ^b^ International Workshop on chronic lymphocytic leukemia
>
> Min = minimum; Max = maximum

Figure 7 to Figure 14 show overall survival and progression-free
survival for specific disease types. In all histologies, the results
were similar for the Aranesp-treated patients and placebo patients.

[]{#__RefHeading___Toc68443256 .anchor}Figure 7. Study 20000161:
Progression-free Survival\
(Aggressive Non-Hodgkin's Lymphoma)

![](media/image8.wmf){width="6.059722222222222in" height="2.5125in"}

[]{#__RefHeading___Toc68443257 .anchor}Figure 8. Study 20000161:
Progression-free Survival\
(Indolent Non-Hodgkin's Lymphoma)

![](media/image9.wmf){width="6.029861111111111in"
height="2.4972222222222222in"}

[]{#__RefHeading___Toc68443258 .anchor}Figure 9. Study 20000161:
Progression-free Survival\
(Multiple Myeloma)

![](media/image10.wmf){width="6.2in" height="2.7375in"}

[]{#__RefHeading___Toc68443259 .anchor}Figure 10. Study 20000161:
Progression-free Survival\
(Chronic Lymphocytic Leukemia)

![](media/image11.wmf){width="6.169444444444444in"
height="2.6020833333333333in"}

[]{#__RefHeading___Toc68443260 .anchor}Figure 11. Study 20000161:
Overall Survival\
(Aggressive Non-Hodgkin's Lymphoma)

![](media/image12.wmf){width="6.279861111111111in"
height="2.5944444444444446in"}

[]{#__RefHeading___Toc68443261 .anchor}Figure 12. Study 20000161:
Overall Survival\
(Indolent Non-Hodgkin's Lymphoma)

![](media/image13.wmf){width="6.169444444444444in"
height="2.6395833333333334in"}

[]{#_Ref68437138 .anchor}

Figure 13. Study 20000161: Overall Survival\
(Multiple Myeloma)

![](media/image14.wmf){width="6.089583333333334in"
height="2.6319444444444446in"}

[]{#__RefHeading___Toc68443263 .anchor}Figure 14. Study 20000161:
Overall Survival\
(Chronic Lymphocytic Leukemia)

![](media/image15.wmf){width="6.239583333333333in"
height="2.729861111111111in"}

## Pooled Randomized, Double-blind, Placebo-controlled Trials

As the safety signals observed in the INT-76 trial were observed during
the first 4 months on study, evaluation of survival and disease
progression endpoints within the first 16 weeks of exposure to
erythropoietic therapies is appropriate. In addition to the two phase 3
studies already discussed, data from 2 other placebo-controlled studies
in anemic cancer patients who were receiving concurrent chemotherapy are
available and can be included in a pooled analysis of survival and
disease progression. The controlled portion of the randomized,
controlled trials included a follow-up of 16 weeks.

###  Study 980291

[]{#OLE_LINK2 .anchor}Study 980291 (Kotasek et al, 2003) was a
dose-finding, double-blind, placebo-controlled study that evaluated the
safety and efficacy of Aranesp administered once every 3 weeks
(Schedule 1) or once every 4 weeks (Schedule 2) in patients with mixed
solid tumors and chemotherapy-induced anemia (hemoglobin concentration
≤ 11 g/dL). Four hundred five patients were randomly assigned on a 1:4
ratio to Aranesp or placebo. Baseline demographics are shown in Table 5
and Table 6. []{.mark}

Table 5. Study 980291 (Schedule 1):\
Baseline Demographics

+------------------------+----------------------+----------------------+
|                        | Placebo              | Aranesp              |
|                        |                      |                      |
|                        | N = 51               | N = 198              |
+------------------------+----------------------+----------------------+
| Sex (n/%)              | 16 (31)              | 56 (28)              |
|                        |                      |                      |
| > Men                  | 35 (69)              | 142 (72)             |
| >                      |                      |                      |
| > Women                |                      |                      |
+------------------------+----------------------+----------------------+
| Age (yr)               | 56                   | 58                   |
|                        |                      |                      |
| > Median               | 22 - 77              | 29 - 84              |
| >                      |                      |                      |
| > Min - Max            |                      |                      |
+------------------------+----------------------+----------------------+

> Min = minimum; Max = maximum

[]{#__RefHeading___Toc68443244 .anchor}Table 6. Study 980291 (Schedule
2):\
Baseline Demographics

+------------------------+----------------------+----------------------+
|                        | Placebo              | Aranesp              |
|                        |                      |                      |
|                        | N = 31               | N = 125              |
+------------------------+----------------------+----------------------+
| Sex (n/%)              | 7 (23)               | 44 (35)              |
|                        |                      |                      |
| > Men                  | 24 (77)              | 81 (65)              |
| >                      |                      |                      |
| > Women                |                      |                      |
+------------------------+----------------------+----------------------+
| Age (yr)               | 58                   | 63                   |
|                        |                      |                      |
| > Median               | 34 - 74              | 33 - 83              |
| >                      |                      |                      |
| > Min - Max            |                      |                      |
+------------------------+----------------------+----------------------+

> Min = minimum; Max = maximum

Patients who completed the blinded treatment phase and continued to
receive chemotherapy were given the option to receive open-label Aranesp
for an additional 12 weeks. As patients receiving placebo during the
blinded treatment phase were allowed to receive Aranesp during the
open-label phase, for the analysis of progression-free and overall
survival, patients were censored at the time they received their first
dose of Aranesp treatment in the open-label phase. No long-term
information was collected for patients in this study.

###  Study 990114

Study 990114 (Hedenus et al, 2002) was a randomized, double-blind,
placebo‑controlled study in which 66 patients with lymphoid malignancies
and chemotherapy-induced anemia (hemoglobin concentration 11 g/dL) were
randomly assigned to receive Aranesp at 1 of 3 dose levels or placebo
for 12 weeks, followed by a 4-week observation period. Baseline
demographics and disease characteristics were similar between treatment
groups (Table 7). No long-term information was collected for patients in
this study.

[]{#__RefHeading___Toc68443245 .anchor}Table 7. Study 990114: Baseline
Demographics

+-------------------------------------+---------------+---------------+
|                                     | Placebo       | Aranesp       |
|                                     |               |               |
|                                     | N = 11        | N = 55        |
+-------------------------------------+---------------+---------------+
| Sex (n/%)                           | 2 (18)        | 35(64)        |
|                                     |               |               |
| Men                                 | 9 (82)        | 20 (36)       |
|                                     |               |               |
| Women                               |               |               |
+-------------------------------------+---------------+---------------+
| Age (yr)                            | 63            | 68            |
|                                     |               |               |
| Median                              | 25 -80        | 20 - 84       |
|                                     |               |               |
| Min -Max                            |               |               |
+-------------------------------------+---------------+---------------+
| Disease type (n/%)                  | 3 (27)        | 8 (15)        |
|                                     |               |               |
| Hodgkin's disease                   | 3 (27)        | 11 (20)       |
|                                     |               |               |
| Non-Hodgkin's lymphoma              | 2 (18)        | 10 (18)       |
|                                     |               |               |
| Chronic lymphocytic leukemia        | 0             | 11 (20)       |
|                                     |               |               |
| Waldenstrom's macroglobulinaemia    | 3 (27)        | 15 (27)       |
|                                     |               |               |
| Multiple myeloma                    |               |               |
+-------------------------------------+---------------+---------------+
| ECOG Performance status (n/%)       | 5 (45)        | 16 (29)       |
|                                     |               |               |
| 0                                   | 6 (55)        | 32 (58)       |
|                                     |               |               |
| 1                                   | 0             | 7 (13)        |
|                                     |               |               |
| 2                                   |               |               |
+-------------------------------------+---------------+---------------+

> Min = minimum; Max = maximum

### Pooled Analyses

The pooled analyses of 1129 patients in the 4 double-blind,
placebo-controlled studies are consistent with the observations within
each individual phase 3 study (Table 8). The progression-free survival
and overall survival were similar between the treatment and the
no-treatment groups. The estimated hazard ratios related to Aranesp use
were 0.93 (95% CI: 0.79, 1.09) and 0.97 (0.79, 1.18), for
progression-free and overall survival, respectively (Figure 15 and
Figure 16). In particular, there was no difference between groups over
the first 16 weeks of treatment.

[]{#__RefHeading___Toc68443246 .anchor}Table 8. Treatment Endpoint
Summaries by Study

  ------------- ------------- ----------- ---------- ------------------ ----------
                              Overall                Progression-free   
                              Survival               Survival           

                              Hazard      95% CI     Hazard Ratio:      95% CI
                              Ratio:                 Aranesp to Placebo 
                              Aranesp to                                
                              Placebo                                   

  Study 980297  NSCLC         0.85        0.62, 1.17 0.91               0.69, 1.21

                SCLC          0.62        0.38, 1.01 0.59               0.38, 0.93

                All           0.77        0.59, 1.01 0.79               0.62, 1.00
                Histologies                                             

  []{.mark}                                                             

  Study         Aggressive    0.95        0.36, 2.53 0.80               0.34, 1.89
  20000161      NHL                                                     

                Indolent NHL  1.41        0.51, 3.90 1.04               0.52, 2.09

                Multiple      1.22        0.79, 1.89 1.08               0.76, 1.54
                Myeloma                                                 

                CLL           1.84        0.76, 4.43 1.18               0.66, 2.12

                All           1.36        0.98, 1.90 1.06               0.82, 1.38
                Histologies                                             

                                                                        

  Study         All           0.50        0.17, 1.46 0.72               0.39, 1.32
  980291^a^     Histologies                                             

  Study         All           NE                     1.07               0.49, 2.35
  980291^b^     Histologies                                             

                                                                        

  Study 990114  All           NE                     NE                 
                Histologies                                             

                                                                        

  Pooled        All           0.97        0.79, 1.18 0.93               0.79, 1.09
  Analysis      Histologies                                             
  ------------- ------------- ----------- ---------- ------------------ ----------

CLL = chronic lymphocytic leukemia; NE = not estimable because of too
few events; NHL = non-Hodgkin's lymphoma; NSCLC = non-small cell lung
cancer; SCLC = small-cell lung cancer

^a^ Schedule 1

^b^ Schedule 2

[]{#__RefHeading___Toc68443264 .anchor}Figure 15. Pooled Data Set:
Progression-free Survival

![](media/image16.wmf){width="5.789583333333334in"
height="2.6395833333333334in"}

[]{#__RefHeading___Toc68443265 .anchor}Figure 16. Pooled Data Set:
Overall Survival

![](media/image17.wmf){width="5.8694444444444445in"
height="2.6319444444444446in"}

## Relationship Between Hemoglobin Metrics and Survival

Individual, double-blind, placebo-controlled studies in
chemotherapy-induced anemia and the pooled analysis revealed no
suggestion of an adverse effect of Aranesp on progression-free or
overall survival. Given the lack of any previous suggestion of survival
issues despite the substantial patient-year experience with
erythropoietic-stimulating proteins in both clinical research and
oncology-practice settings, Amgen considered that the signals observed
in the INT-76 and ENHANCE trials could have been related to unique
design features of those studies. Therefore, we investigated our
clinical trial database, using the pooled clinical trial database
previously described (Section 7.2), for factors included in the design
of the INT-76 and ENHANCE trials, namely high baseline hemoglobin
levels, rapid hemoglobin increases (as a result of
higher-than-recommended doses, and the use of non-myelosuppressive
radiation therapy in the case of the ENHANCE trial), as well as the
inclusion of selected tumor types that could theoretically represent
malignancies susceptible to proliferation through EPO-R engagement. Cox
regression models stratified by study protocol were used to examine the
relationship between treatment and baseline hemoglobin. In addition,
time-dependent hemoglobin-related covariates, patients reaching
hemoglobin thresholds, and rates of hemoglobin increase with time on
study were used to examine the potential effect of changes in hemoglobin
concentrations and their relationship to progression-free survival and
overall survival. In these analyses, to exclude an effect of hemoglobin
increases due to transfusions for patients receiving a transfusion,
hemoglobin measurements on the day of a transfusion and for the next
28 days after a transfusion were excluded.

An association was observed between both improved survival and
progression-free survival and a on-study increase in hemoglobin
concentration of ≥ 1 g/dL in 14 days. Similar associations were seen
with achieving an on-study hemoglobin concentration of ≥ 13 g/dL (Table
9).

[]{#__RefHeading___Toc68443247 .anchor}Table 9. Pooled Analysis: Cox
Regression Models for

Progression-free Survival and Overall Survival

  --------------------- -------------------- --------- --------- ----------
  Model^a^              Endpoint             p-value   Hazard\   95% CI
                                                       ratio     

  ≥ 1 g/dL hgb increase Survival             0.001     0.43      0.34, 0.56
  in 14 days                                                     

  ≥ 1 g/dL hgb increase Progression-free     0.001     0.51      0.42, 0.62
  in 14 days            Survival                                 

                                                                 

  Achieved hgb of ≥ 13  Survival             0.001     0.56      0.40, 0.79
  g/dL                                                           

  Achieved hgb of ≥ 13  Progression-free     0.001     0.66      0.51, 0.84
  g/dL                  Survival                                 
  --------------------- -------------------- --------- --------- ----------

^a^ Models stratified by study; adjusted for Aranesp versus placebo and
baseline hemoglobin value

CI = confidence interval; hgb = hemoglobin

Comparisons of progression-free and overall survival between patients
receiving Aranesp and placebo are shown by baseline hemoglobin
categories in Figure 17 and Figure 18. These analyses suggest a benefit
of Aranesp administration relative to placebo in terms of
progression-free survival and overall survival for patients with severe
anemia (baseline hemoglobin concentration \< 9 g/dL), with a relative
risk (95% CI) of 0.62 (0.45, 0.86) and 0.69 (0.46, 1.02), respectively.
No significant differences between Aranesp and placebo were observed for
the other baseline hemoglobin categories for either endpoint.

[]{#__RefHeading___Toc68443266 .anchor}Figure 17. Pooled Analysis:
Progression-free Survival for\
Patients with Baseline Hemoglobin

![](media/image18.wmf){width="6.25in" height="5.2125in"}

[]{#__RefHeading___Toc68443267 .anchor}Figure 18. Pooled Analysis:
Overall Survival for\
Patients by Baseline Hemoglobin

![](media/image19.wmf){width="6.039583333333334in"
height="5.842361111111111in"}

These observations do not support the concept that the adverse outcomes
observed by Leyland-Jones (2003) and Henke et al (2003) were the results
of a high hemoglobin (baseline or target) and hemoglobin rate of rise.
However, firm conclusions regarding the effects of epoetin
pharmacodynamics on progression and survival cannot be drawn from these
results, as very high targets and rates of hemoglobin increases could
not be studied given the original design of the Aranesp trials.
Responsiveness to erythropoietic therapy may be a marker of general
health rather than a reason for improved outcomes.

## Tumor Types

To explore whether particular tumor types may be more susceptible to
tumor stimulation by Aranesp, we examined progression-free survival and
overall survival by histology. We did not observe a significant risk for
overall survival or progression-free survival in any malignancy type
analyzed (Figure 19 and Figure 20). For breast cancer, the tumor type
studied in the INT-76 trial, no statistically significant increase in
mortality was observed. The ENHANCE trial included patients with
head-and-neck cancer. In the pooled analysis, only 1 patient had
head-and-neck cancer and was classified as "GI Other".

[]{#__RefHeading___Toc68443268 .anchor}Figure 19. Progression-free
Survival Hazard Ratios\
Associated With Aranesp Versus Placebo Therapy

![](media/image20.wmf){width="5.75in" height="2.6770833333333335in"}

> CLL = chronic lymphocytic leukemia; DA = darbepoetin alfa; GI =
> gastrointestinal; NSCLC = non-small cell lung cancer; PL = placebo;
> SCLC = small-cell lung cancer

[]{#__RefHeading___Toc68443269 .anchor}Figure 20. Overall Survival
Hazard Ratios\
Associated With Aranesp Versus Placebo Therapy

![](media/image21.wmf){width="5.879861111111111in"
height="2.6020833333333333in"}

> CLL = chronic lymphocytic leukemia; DA = darbepoetin alfa; GI =
> gastrointestinal; NSCLC = non-small cell lung cancer; PL = placebo;
> SCLC = small-cell lung cancer

## Summary of Aranesp Clinical Trial Findings

In summary, findings from analyses of the Aranesp clinical trial
database indicate that, when prescribed in accord with the approved
dosing regimens, Aranesp treatment is not associated with an increased
risk of tumor progression and mortality in patients with
chemotherapy-induced anemia in multiple different types of cancer.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Data from Aranesp oncology clinical trials do not reveal a        |
|     significant effect on tumor progression or survival after         |
|     short-term treatment (12 weeks) or in long‑term follow-up (up to  |
|     2 years).                                                         |
+-----------------------------------------------------------------------+
| -   Achieving a hemoglobin level of 13 g/dL is associated with        |
|     improved survival in cancer patients.                             |
+-----------------------------------------------------------------------+
| -   The clinical trials that have raised concerns over tumor          |
|     progression and survival have been performed with Epoetin alfa    |
|     and Epoetin beta. Such findings have not been observed with       |
|     Aranesp and, thus, do not constitute a class effect.              |
+-----------------------------------------------------------------------+

[]{.mark}

[]{.mark}

# OVERALL BENEFIT/RISK ASSESSMENT

Aranesp therapy improves chemotherapy-induced anemia and fatigue,
reduces the need for transfusions, and enhances the quality of life for
oncology patients afflicted with a variety of malignancies. Significant
reductions in transfusion requirements are associated with Aranesp
therapy (Hedenus et al, 2003; Vansteenkiste et al, 2002). The reduction
of transfusions has many benefits, including reductions in the risk of
transfusion reactions and transmission of infectious diseases. Patients
treated with Aranesp also experience significant improvement in fatigue
(Hedenus et al, 2003; Vansteenkiste et al, 2002).

Although safety observations have been reported from both Aranesp
clinical trials and Aranesp practice experience, these events are
uncommon and have been proactively communicated in the package insert.
When prescribed in accord with approved product labeling and guidelines,
Aranesp substantially improves the lives of patients with grievous
illnesses. No evidence from either preclinical or clinical analyses
suggests that Aranesp promotes tumor progression or reduces survival.
The benefit/risk profile for Aranesp remains very favorable.

# Ongoing Studies and Pharmacovigilance Program

As discussed, Aranesp has had no detrimental effect on disease
progression or overall survival in completed oncology placebo-controlled
trials evaluating anemia outcomes. In order to more rigorously evaluate
relevant cancer endpoints such as tumor response, time to tumor
progression, and survival, oncology studies are typically randomized,
controlled trials in patient populations with a uniform tumor type,
stage, and treatment history. Treatment groups are balanced for
important outcome predictors for specific malignancies. In addition,
they contain prospective inclusion of survival as an endpoint; and
adequate sample size, follow-up, and power to detect a clinically
meaningful effect (Nottage and Siu, 2002). Amgen has initiated one large
oncology trial and is supporting investigators conducting additional
trials as part of the ongoing Aranesp Pharmacovigilance Program.

Amgen believes that most studies designed to investigate anemia outcomes
do not provide definitive information on tumor progression or survival
endpoints. Amgen further does not believe that it is helpful to append
survival outcomes to short chemotherapy-induced anemia studies that,
although designed rigorously for hematologic and patient-reported
outcome endpoints, do not contain essential design elements to allow
conclusive assessment of cancer outcomes.

To more formally and prospectively address disease progression and
survival endpoints in patients who are receiving Aranesp therapy, the
Aranesp Pharmacovigilance Program includes 5 randomized, prospective
clinical trials designed to evaluate specific cancer endpoints in a
variety of malignancies (Table 10). These clinical trials include both
investigator-sponsored studies (FR-2003-3005, DE-2001-0033,
DE-2002-0015, and SE-2002-9001) and an Amgen-sponsored study (20010145).
The investigator-sponsored trials are open-label, randomized studies of
Aranesp versus observation, and Amgen is collaborating with the
investigators to support optimum study design, study conduct, and safety
monitoring. As described below (Section 9.2), the Amgen-sponsored study
(20010145) is randomized, double-blind, and placebo-controlled.
Endpoints include event-free survival, relapse, overall survival, and
locoregional control in patients receiving combination chemotherapy for
extensive small-cell lung cancer.

The pharmacovigilance program includes large trials in patients with
breast cancer and head-and-neck cancer (DE-2001-0033, DE-2002-0015, and
SE-2002-9001), the 2 tumor types included in the INT-76 and ENHANCE
trials (Table 10). As Aranesp has received marketing approval for the
treatment of chemotherapy-induced anemia in all non‑myeloid
malignancies, studies also were included in patients with small-cell
lung cancer (20010145) and non-Hodgkin's lymphoma
(FR-2003-3005).[]{#_Ref66945216 .anchor}

Table 10. Aranesp Pharmacovigilance Program Trials:\
Power and Sensitivity Calculations

+---------+--------+----------+--------+-------+------+------+------+
|         |        |          |        | P     |      | Surv |      |
|         |        |          |        | rogre |      | ival |      |
|         |        |          |        | ssion |      | Sens |      |
|         |        |          |        | Se    |      | itiv |      |
|         |        |          |        | nsiti |      | ity\ |      |
|         |        |          |        | vity\ |      | 80%  |      |
|         |        |          |        | 80%   |      | P    |      |
|         |        |          |        | Power |      | ower |      |
+---------+--------+----------+--------+-------+------+------+------+
| Study   | Tumor  | Design   | Ac     | \%    | Ha   | \%   | Ha   |
| ID      | Type   |          | crual\ |       | zard |      | zard |
|         |        |          | J      |       | R    |      | R    |
|         |        |          | anuary |       | atio |      | atio |
|         |        |          | 2004   |       |      |      |      |
+---------+--------+----------+--------+-------+------+------+------+
| FR-20   | N      | R-CHOP   | 12/600 | EFS   | 1.45 | 65%  | 1.53 |
| 03-3005 | on-Hod | 14 or    |        | 55% ± |      | ±    |      |
|         | gkin's |          |        | 11%   |      | 11%  |      |
|         | ly     | R-CHOP   |        | at    |      | at   |      |
|         | mphoma | 21       |        | 3     |      | 3 y  |      |
|         |        |          |        | years |      | ears |      |
|         |        | ±        |        |       |      |      |      |
|         |        | Aranesp  |        |       |      |      |      |
+---------+--------+----------+--------+-------+------+------+------+
| DE-20   | Breast | Se       | 3      | RFS   | 1.53 | 80%  | 1.70 |
| 01-0033 |        | quential | 00/720 | 70% ± |      | ±    |      |
|         |        | or       |        | 10%   |      | 10%  |      |
|         |        | dose-int |        | at    |      | at   |      |
|         |        | ensified |        | 5     |      | 5 y  |      |
|         |        | chem     |        | years |      | ears |      |
|         |        | otherapy |        |       |      |      |      |
|         |        | ±        |        |       |      |      |      |
|         |        | Aranesp  |        |       |      |      |      |
+---------+--------+----------+--------+-------+------+------+------+
| DE-20   | Breast | Adjuvant | 1      | EFS   | 1.35 | 75%  | 1.48 |
| 02-0015 |        | chem     | 0/1000 | 60% ± |      | ±7%\ |      |
|         |        | otherapy |        | 9% at |      | at   |      |
|         |        | ±        |        | 5     |      | 5 y  |      |
|         |        | Aranesp  |        | years |      | ears |      |
+---------+--------+----------+--------+-------+------+------+------+
| SE-20   | Head   | Radi     | 2      | Local | 1.42 | 60%  | 1.49 |
| 02-9001 | and    | otherapy | 26/600 | Co    |      | ±    |      |
|         | neck   | ±        |        | ntrol |      | 11%  |      |
|         |        | Aranesp  |        | 50% ± |      | at   |      |
|         |        |          |        | 11%   |      | 5 y  |      |
|         |        |          |        | at    |      | ears |      |
|         |        |          |        | 5     |      |      |      |
|         |        |          |        | years |      |      |      |
+---------+--------+----------+--------+-------+------+------+------+
| 2       | Small  | C        | 1      | EFS   | 1.32 | 50%  | 1.42 |
| 0010145 | cell   | isplatin | 70/600 | 25% ± |      | ±    |      |
|         | lung   | /        |        | 9%    |      | 10%  |      |
|         |        | Carbopla |        | at\   |      | at\  |      |
|         |        | tin/VP16 |        | 6     |      | 6    |      |
|         |        | ±        |        | m     |      | mo   |      |
|         |        | Aranesp  |        | onths |      | nths |      |
+---------+--------+----------+--------+-------+------+------+------+

> ± indicates detectable difference; EFS = event-free survival; RFS =
> relapse-free survival

These investigator-sponsored studies are being conducted in conjunction
with data safety monitoring boards and interim safety analyses to ensure
careful monitoring. One trial being conducted in patients with
head-and-neck cancer receiving curative radiotherapy includes patients
with hemoglobin concentrations up to 14.5 g/dL and has a hemoglobin
target of 15.5 g/dL (SE-2002-9001). This trial has been the subject of a
recent interim safety analysis, and the monitoring committee has
recommended continuation of the trial as planned. All studies directly
sponsored by Amgen are conducted in accord with the approved product
labeling for both dosing and hemoglobin targets.

Three of the European trials (20010145, DE-2001-0033 and DE-2002-0015)
use a target hemoglobin value of 14 g/dL, which corresponds to approved
label upper limit for dosing in the European Aranesp Summary of Product
Characteristics. Although this number differs from that outlined in the
United States package insert (13 g/dL), it was also the target selected
for pivotal trials 980297 and 20000161, studies that revealed no
increase in tumor progression or survival in conjunction with Aranesp
therapy.

## Pharmacovigilance Program Analyses

A summary of the power and sensitivity of the Aranesp Pharmacovigilance
Program is provided in Table 10. Individually, these trials have 80%
power to rule out an increase in risk of 32% to 53% for disease
progression and of 42% to 70% for survival with Aranesp, which include
the magnitude of the risk observed in the ENHANCE and INT-76 studies. In
combination with clinical experience derived from Amgen-sponsored trials
containing long-term follow-up, the total patient exposure in the
Aranesp Pharmacovigilance Program is 4176 patients, representing
1266 patient-years through March 2004 and increasing to
8503 patient-years in 2008 (Table 11). When pooled in a meta-analysis,
they collectively represent the opportunity to detect a considerably
smaller safety signal across a broader range of tumors.

[]{#__RefHeading___Toc68443249 .anchor}Table 11. Amgen Trials and
Investigator-sponsored Trials:\
Pharmacovigilance Program Patient-years

  --------------- -------- --------------- --------- --------- --------- ---------
                           Cumulative and                                
                           projected                                     
                           patient-years                                 
                           of follow-up^a^                               

  Study ID        N        Q1 2004         Q1 2005   Q1 2006   Q1 2007   Q1 2008

  980297          312      360             368       372       374       374

  20000161        344      638             791       920       1015      1145

  20010145        600      88              263       473       613       700

  FR-2003-3005    600      0               59        243       529       899

  DE-2001-0033    720      67              354       852       1480      2074

  DE-2002-0015    1000     0               99        409       894       1527

  SE-2002-9001    600      113             405       857       1344      1784

  Total           4176     1266            2339      4126      6249      8503
  --------------- -------- --------------- --------- --------- --------- ---------

> ^a^ Assumes exponential survival, uniform accrual, and all patients
> followed until death

## Amgen Study 20010145: Study in Small-cell Lung Cancer

Study 20010145 is a randomized, double-blind, placebo-controlled study
to evaluate the effects on survival of increasing or maintaining
hemoglobin with Aranesp in patients receiving chemotherapy for
previously untreated, extensive-stage small-cell lung cancer.
Approximately 600 patients will be followed until death or until all
patients have completed their end-of-study treatment visit and 496
deaths have occurred.

The co-primary endpoints for this study are change in hemoglobin from
baseline to the end of the chemotherapy treatment period and survival
time. In addition, the safety of Aranesp will be further evaluated based
on the incidence and severity of adverse events, changes in laboratory
results, changes in vital signs, and the incidence of concomitant
medication use. This study includes a data monitoring committee.

## Study FR-2003-3005: Study in Diffuse Large B-cell Lymphoma

The FR-2003-3005 study is an open-label, randomized, multicenter,
phase 3 investigator-sponsored trial being run by Groupe d'Etude des
Lymphomes de l'Adulte (Randomized Study of Intensified CHOP plus
Rituximab Given Every 14 days \[R-CHOP 14\] versus CHOP plus Rituximab
Given Every 21 Days \[R-CHOP 21\] and Randomized Study of
Frontline/Prophylactic Darbepoetin alfa Treatment versus Usual
Symptomatic Treatment of Anemia in Untreated Patients with Diffuse Large
Cell Lymphoma). It is anticipated that 600 patients will be enrolled.
The study evaluates the efficacy of rituximab plus CHOP chemotherapy
given every 14 days (R-CHOP 14) compared with the standard R‑CHOP 21
regimen, with and without Aranesp in previously untreated patients aged
66 to 80 years with diffuse large B-cell lymphoma. The primary endpoint
is event-free survival. Aranesp will be administered weekly for patients
with hemoglobin concentrations \< 13 g/dL. An interim analysis for
safety and for the primary efficacy endpoint is planned after 2 years.

## Study SE-2002-9001: Study in Head-and-Neck Cancer

This study is an open-label, randomized, multicenter, phase 3
investigator-sponsored trial to evaluate the effects of Aranesp in
patients with head-and-neck cancer receiving primary curative
radiotherapy (Study of the Importance of Novel Erythropoiesis
Stimulating Protein \[Aranesp\] for the Effect of Radiotherapy in
Patients with Primary Squamous Cell Carcinoma of the Head and Neck). It
is anticipated that 600 patients will be accrued. The clinical
hypothesis is that the addition of Aranesp to standard curative
radiotherapy treatment of head-and-neck cancer will increase the
locoregional disease control rate. The study is being performed by the
Danish Head and Neck Cancer Study Group.

The primary endpoint of this study is loco-regional control (T+N
localization). Secondary endpoints include local control
(T-localization), overall survival, disease-specific survival, and
hemoglobin concentrations during radiotherapy, and acute toxicity. A
formal interim analysis will be performed after the observation of 150
locoregional failures.

## Study DE-2001-0033: Study in Neoadjuvant Breast Cancer

This study is an open-label, randomized, multicenter, phase 3 trial to
evaluate the effects of preoperative chemotherapy using a sequential
dose-dense and dose-intensified regimen of epirubicin, paclitaxel, and
CMF compared with preoperative sequential administration of epirubicin
and cyclophosphamide followed by paclitaxel in patients with breast
cancer (Randomized, Preoperative Epirubicin Paclitaxel Aranesp Study
Comparing Sequential versus Dose Intensified Chemotherapy in Breast
Cancer Patients and Randomized to Darbepoetin alfa versus Usual Anemia
Therapy). The study is being conducted by the German Gynecological
Oncology Study group. Seven hundred twenty patients are planned to be
accrued to this study.

The primary endpoint of this study is the effect of dose-dense,
dose-intense preoperative chemotherapy on relapse-free survival.
Secondary endpoints are the effects of preoperative dose-dense,
dose-intense preoperative chemotherapy on clinical and pathological
remission rates and the effects of Aranesp on remission rate and quality
of life. An interim analysis at 3 years is planned for safety and for
the primary endpoint. This study includes a data monitoring committee.

## Study DE-2002-0015: Study in Adjuvant Breast Cancer

This study is an open-label, randomized, multicenter, phase 3 trial to
evaluate the effects of adjuvant chemotherapy with and without Aranesp
on event-free survival rates in patients with breast cancer who have
\> 3 positive lymph nodes (Adjuvant Therapy of Breast Cancer: Relevance
of Erythropoiesis-stimulating Factors for Survival in High-risk Breast
Cancer). One thousand patients will be accrued to this study. Patients
will receive local radiotherapy at the completion of chemotherapy. The
study is being conducted by the West German Study Group.

The primary endpoint is event-free survival, defined as relapse (local
or distant), deaths from any cause, or second primaries. The secondary
endpoints are overall survival, local relapse rate, toxicity, cognitive
function, and severity of patient-reported anemia symptoms. This study
includes a data monitoring committee.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Chemotherapy-induced anemia studies often have design elements    |
|     that preclude meaningful assessment of survival and               |
|     tumor-progression outcomes.                                       |
+-----------------------------------------------------------------------+
| -   Amgen has proactively developed a robust Aranesp                  |
|     Pharmacovigilance Program that includes epidemiologic studies,    |
|     appropriately well-designed oncology clinical trials, and careful |
|     safety data monitoring.                                           |
+-----------------------------------------------------------------------+
| -   With over 8500 patient-years of follow-up, the Aranesp            |
|     Pharmacovigilance Program will have significant sensitivity to    |
|     detect potential signals regarding survival and tumor progression |
|     in multiple oncology populations.                                 |
+-----------------------------------------------------------------------+

# SUMMARY

Aranesp is a unique erythropoietic molecule that is distinct from other
erythropoietic-stimulating proteins in terms of amino acid sequence,
glycosylation, receptor affinity, and pharmacokinetic/pharmacodynamic
profile. Aranesp is licensed for the treatment of anemia in patients
with non-myeloid malignancies receiving chemotherapy. Aranesp reduces
fatigue and the need for transfusions, and improves quality of life for
patients with grievous illnesses. Aranesp has a favorable benefit/risk
profile for the treatment of chemotherapy-induced anemia when used in
accord with approved product labeling and published guidelines. Through
December 2003, more than 427,000 patients have received Aranesp therapy,
representing more than 268,000 patient-years of experience.

The clinical trials that have raised concerns over tumor progression and
survival were performed with Eprex and NeoRecormon. No such findings
have been observed with Aranesp and, thus, do not suggest a class
effect. The unique attributes of Aranesp may be relevant to the
differences in the safety profile observed with these different
erythropoietic-stimulating proteins.

EPO-R are expressed on hematopoietic tissues, other non-hematopoietic
normal tissues and on a variety of tumors of different tissue origins.
However, the presence of EPO-R, as measured by mRNA, protein, or
receptor binding, does not always correlate with functional EPO-R on
cells. These receptors are typically of lower affinity than those
expressed in hematopoietic tissues and are of uncertain clinical
relevance for cancer patients. Observations of in vitro proliferation of
tumor cells with epoetins are mixed and are of uncertain relevance. No
such in vitro studies have been reported with Aranesp. Aranesp therapy
in tumor-bearing animals have shown benefit in conjunction with
radiotherapy.

No reports suggest that EPO-R is amplified or constitutively activated
in human tumors of non-hematopoietic origin. No animal models, or
clinical syndromes, have been found in which prolonged exposure to EPO
increases the incidence of tumors. No evidence suggests that EPO-R
undergoes oncogenic transformation in solid tumors.

Amgen has proactively addressed safety observations. The Aranesp label
already represents the low potential for oncology patients to experience
thrombotic events in conjunction with erythropoietic-stimulating
proteins. Analysis of more than 1100 patients receiving Aranesp in
randomized, blinded, placebo-controlled trials reveal no evidence for
increased tumor progression or reduced survival. Furthermore, Amgen is
sponsoring a large randomized, placebo-controlled trial in patients with
small-cell lung cancer and is collaborating with investigators
conducting 4 large randomized, controlled trials in patients with
lymphoma and breast cancer receiving chemotherapy, and in patients with
head-and-neck cancer receiving radiotherapy. These studies should permit
further definition of Aranesp benefit/risk in cancer patients with a
range of malignancies. In addition, in response to the INT-76 and
ENHANCE trial results, Amgen has proactively contacted all worldwide
investigators using Aranesp in investigator-sponsored oncology trials to
review protocols and dosing regimens, in order to confirm rigor in trial
design and conduct and to strengthen support for patient safety.

Amgen believes that erythropoietic treatment of non-anemic patients, or
treatment regimens with higher-than-approved target hemoglobin values,
should be evaluated in the setting of well-designed and executed
clinical trials sufficiently powered to permit safety assessments. The
results of such trials should be fully publicly disclosed. Amgen
respects the prudence of the FDA and ODAC in weighing observations from
all erythropoietic therapies but also believes that product assessments
should be evidence-based and driven, in large part, by product specific
observations.

+-----------------------------------------------------------------------+
| **Key Points:**                                                       |
+-----------------------------------------------------------------------+
| -   Amgen originally cloned and developed Epoetin alfa (Procrit,      |
|     Epogen) and created and developed darbepoetin alfa (Aranesp).     |
+-----------------------------------------------------------------------+
| -   Aranesp is considered a distinct molecular entity from            |
|     scientific, clinical, legal, and regulatory perspectives.         |
+-----------------------------------------------------------------------+
| -   Aranesp has a favorable benefit/risk profile for the treatment of |
|     chemotherapy-induced anemia when used in accord with approved     |
|     product labeling and published guidelines. Aranesp reduces both   |
|     fatigue and the need for transfusions and improves quality of     |
|     life for patients with grievous illnesses.                        |
+-----------------------------------------------------------------------+
| -   Cancer patients have an increased risk of thrombotic events; risk |
|     factors include the underlying type of malignancy, stage of       |
|     disease, prior thrombotic events, performance status, anemia, and |
|     exposure to erythropoietic-stimulating proteins. Thrombotic       |
|     events are appropriately represented in the Aranesp prescribing   |
|     information.                                                      |
+-----------------------------------------------------------------------+
| -   The clinical trials that have raised concerns over tumor          |
|     progression and survival have been performed with Epoetin alfa    |
|     and Epoetin beta. Such findings have not been observed with       |
|     Aranesp and, thus, do not constitute a class effect.              |
+-----------------------------------------------------------------------+
| -   There is no preclinical or clinical evidence that Aranesp         |
|     promotes cancer cell proliferation, tumor progression, or reduced |
|     oncology patient survival.                                        |
+-----------------------------------------------------------------------+
| -   With more than 8500 patient years of follow-up, the Aranesp       |
|     Pharmacovigilance Program will have significant power and         |
|     sensitivity to detect potential signals regarding survival and    |
|     tumor progression in multiple oncology populations.               |
+-----------------------------------------------------------------------+

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