Article

Phase I/II Clinical Trial of the Anti-Podoplanin
Monoclonal Antibody Therapy in Dogs with
Malignant Melanoma
Satoshi Kamoto 1,†, Masahiro Shinada 1,†, Daiki Kato 1,*, Sho Yoshimoto 1, Namiko Ikeda 1,
Masaya Tsuboi 2, Ryohei Yoshitake 1, Shotaro Eto 1, Yuko Hashimoto 2, Yosuke Takahashi 2,James Chambers 3, Kazuyuki Uchida 3, Mika K. Kaneko 4, Naoki Fujita 1, Ryohei Nishimura 1,
Yukinari Kato 4,5 and Takayuki Nakagawa 1
Laboratory of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, The University ofTokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; veteronut@gmail.com (S.K.);
ms003_shina@yahoo.co.jp (M.S.); syoshimo@g.ecc.u-tokyo.ac.jp (S.Y.); tsubaki5228@gmail.com (N.I.);
g050446@gmail.com (R.Y.); shotaro.nyantaro@gmail.com (S.E.); apom@g.ecc.u-tokyo.ac.jp (N.F.);
surgspartan@g.ecc.u-tokyo.ac.jp (R.N.); anakaga@g.ecc.u-tokyo.ac.jp (T.N.)
2 Veterinary Medical Center, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan;
atsuboi@g.ecc.u-tokyo.ac.jp (M.T.); yuko14hashi@gmail.com (Y.H.);
yousuke1982_root_story@yahoo.co.jp (Y.T.)
3 Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University ofTokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; achamber@g.ecc.u-tokyo.ac.jp (J.C.);
auchidak@g.ecc.u-tokyo.ac.jp (K.U.)
4 Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1,
Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan; k.mika@med.tohoku.ac.jp (M.K.K.);
yukinarikato@med.tohoku.ac.jp (Y.K.)
5 New Industry Creation Hatchery Center, Tohoku University, 2-1, Seiryo-machi, Aoba-ku,
Sendai 980-8575, Japan* Correspondence: adk@g.ecc.u-tokyo.ac.jp; Tel.: +81-03-5841-5405† These authors contributed equally to this work.
1

Received: 29 September 2020; Accepted: 19 November 2020; Published: 23 November 2020

Abstract: Podoplanin (PDPN), a small transmembrane mucin-like glycoprotein, is ectopically
expressed on tumor cells. PDPN is known to be linked with several aspects of tumor malignancies
in certain types of human and canine tumors. Therefore, it is considered to be a novel therapeutictarget. Monoclonal antibodies targeting PDPN expressed in human tumor cells showed obvious
anti-tumor effects in preclinical studies using mouse models. Previously, we generated a cancerspecific mouse–dog chimeric anti-PDPN antibody, P38Bf, which specifically recognizes PDPN
expressed in canine tumor cells. In this study, we investigated the safety and anti-tumor effects of
P38Bf in preclinical and clinical trials. P38Bf showed dose-dependent antibody-dependent cellularcytotoxicity against canine malignant melanoma cells. In a preclinical trial with one healthy dog,
P38Bf administration did not induce adverse effects over approximately 2 months. In phase I/II
clinical trials of three dogs with malignant melanoma, one dog vomited, and all dogs had increased
serum levels of C-reactive protein, although all adverse effects were grade 1 or 2. Severe adverse
effects leading to withdrawal of the clinical trial were not observed. Furthermore, one dog had stabledisease with P38Bf injections. This is the first reported clinical trial of anti-PDPN antibody therapy
using spontaneously occurring canine tumor models.
Keywords: podoplanin; dog; antibody therapy; tumor; melanoma

Cells 2020, 9, 2529; doi:10.3390/cells9112529

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1. Introduction
Podoplanin (PDPN), also known as PA2.26, gp38, T1α, and Aggrus, is a type I transmembranesialoglycoprotein expressed in various types of tissues, including renal podocytes, pulmonary type I
alveolar cells, and lymphatic endothelial cells [1–4]. PDPN plays an essential role in the developmentof the lymphatic system in the embryo and in platelet aggregation [1,2]. In human medicine, PDPN
has been reported to be overexpressed in various types of tumors, including squamous cell carcinoma[5], astrocytoma [6], malignant mesothelioma [7], hemangiosarcoma [8], osteosarcoma [9],germinoma [10], and cancer-associated fibroblasts (CAFs) [11–13]. Similar to humans, PDPN has beenreported to be expressed in renal podocytes, alveolar epithelial cells, and lymphatic endothelial cellsof dogs, and in various types of canine tumors, including malignant melanoma and squamous cell
carcinoma [14–18]. Many reports have demonstrated that PDPN expressed on human and canine
tumors is associated with tumor malignancy through the promotion of malignant proliferation andepithelial–mesenchymal transition (EMT), and that it promotes metastasis by enhancing tumor cell
migration and platelet aggregation [1,2,18–21]. These reports promoted the further evaluation of
PDPN as a therapeutic target.
Immunotherapy using therapeutic antibodies, which have blocking activity between a receptor
and ligand, or antibody-dependent cellular cytotoxic (ADCC) activity, have become the predominantclass of new drugs developed in recent years for various tumors [22–27]. Recently, PDPN has
attracted attention as a novel target antigen for the development of antibody therapy because PDPN
is expressed on various refractory tumors. As a blocking antibody, the anti-PDPN neutralizing
antibodies MS-1 and SZ168, which inhibit the binding of PDPN expressed on tumor cells and C-type
lectin-like receptor 2 expressed on platelets, decreased tumor growth and metastasis in PDPNoverexpressed Chinese hamster ovary (CHO)-K1 cells and human melanoma cell lines xenografted
onto mouse models [28,29]. Furthermore, the anti-human PDPN antibody, NZ-12, showed an
obvious anti-tumor effect against human malignant pleural mesothelioma in an orthotopic xenograftmodel by inducing ADCC activity [30]. However, it is expected that anti-PDPN cytotoxic antibodies
might cause adverse effects because the antibodies could bind to both PDPN-expressing tumors andnormal tissues. To solve this issue, we have established a cancer-specific monoclonal antibody(CasMab) against human PDPN, which recognizes the cancer-specific aberrant glycosylation ofhuman PDPN [31]. By using anti-PDPN CasMab, it is possible to specifically target PDPN expressedon tumor tissues but not on normal tissues. Furthermore, anti-PDPN CasMab inhibited the growthand pulmonary metastasis of human-PDPN-expressing tumors in vivo [32]. Based on these strategies,
immunotherapy using a therapeutic antibody targeting PDPN expressed on tumor cells is considered
to be a promising therapy for patients with PDPN-positive tumors. However, an anti-tumor effect ofanti-PDPN antibody therapy has so far been proven only in mouse models, and evaluation of thesafety of PDPN-targeting therapies is required before first-in-human clinical trials.
Dogs with tumors are often used as research models of human patients with tumors because
dogs live in close proximity to humans. They are influenced by similar environmental factors thatcan lead to cancer development, and many features of spontaneously occurring canine tumors are
similar to those of human tumors in terms of histological morphology, biological behavior, molecularmechanisms, and response to conventional therapy [33–35]. To perform clinical trials using
spontaneously occurring canine tumor models, we developed a cancer-specific anti-canine PDPN
(dPDPN) monoclonal antibody (mAb), PMab-38, which recognizes only dPDPN expression in canine
tumor tissues without recognizing normal canine tissues [16]. Immunohistochemical evaluation
demonstrated 90% of canine melanoma, 83% of canine squamous cell carcinoma, and 82% of canine
pulmonary adenocarcinoma cells, and CAFs were positively stained with PMab-38, while normal
canine tissues were hardly stained by PMab-38 [17,18]. Furthermore, a cancer-specific mouse–dog
chimeric anti-PDPN antibody (P38Bf) originating from mouse monoclonal PMab-38 were shown to
reduce immunological reactions, and P38Bf demonstrated strong anti-tumor effects in a PDPNoverexpressed CHO-K1 cell xenograft mouse model [36,37].
The objective of this study was to evaluate the efficacy and safety of a cancer-specific antidPDPN chimeric antibody: P38Bf. The ADCC activity of the antibody against endogenously dPDPN-

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expressing canine tumor cells was evaluated in vitro. The safety and efficacy of the antibody inclinical cases was evaluated in a phase I/II clinical trial.
2. Materials and Methods
2.1. Cell Culture
Five canine melanoma cell lines (CMM1, CMM2, CMM8, CMM11, and KMeC) were used [38–41]. CMM1, CMM2, and KMeC were maintained in RPMI-1640 medium (FUJIFILM Wako Pure
Chemical Corporation, Osaka, Japan) supplemented with 10% fetal bovine serum (FBS; Cosmo BioCo., Tokyo, Japan) and 50 mg/L gentamicin sulfate (Sigma Chemical Co., St Louis, MO, USA). CMM8
and CMM11 were maintained in D-MEM/Ham’s F-12 medium (FUJIFILM Wako Pure Chemical
Corporation) supplemented with 10% FBS, 100 U/mL penicillin, 100 μg/mL streptomycin, and 250
ng/mL amphotericin B suspension (PSA; FUJIFILM Wako Pure Chemical Corporation). Chinese
hamster ovary (CHO)-K1 and canine PDPN (dPDPN)-expressing CHO-K1 with N-terminal PA tag(CHO/dPDPN) cell lines were also used [15]. CHO-K1 and CHO/dPDPN were cultured in RPMI1640 medium supplemented with 10% FBS and PSA. All cell lines were incubated at 37 °C in a humid
atmosphere with 5% CO2. These conditions were used in the following experiments, unless otherwise
stated.
2.2. Antibody
PMab-38, a mouse anti-dPDPN mAb (ImmunoglobulinG1 (IgG1), kappa), was developed aspreviously described [15]. To generate P38B, a mouse-canine (subclass B) chimeric antibody, theappropriate VH and VL cDNAs of mouse PMab-38 and the CH and CL of canine IgG subclass B were
subcloned into pCAG-Ble and pCAG-Neo vectors (FUJIFILM Wako Pure Chemical Corporation) [36].
To generate a cancer-specific mouse–dog chimeric anti-PDPN antibody (P38Bf), antibody expression
vectors were transfected into BINDS-09 (FUT8-knocked out ExpiCHO-S cells; http://www.medtohoku-antibody.com/topics/001_paper_cell.htm) using the ExpiCHO-S Expression System (Thermo
Fisher Scientific, Waltham, MA, USA). P38Bf was purified using Protein G-Sepharose (GE Healthcare
Bio-Sciences, Pittsburgh, PA, USA).
2.3. Enzyme-Linked Immunosorbent Assay (ELISA)
The concentration of P38Bf in canine serum was measured by a direct ELISA that assayed forbinding to canine PDPN. Canine PDPN protein was prepared from the detergent-soluble membrane
fraction of canine CHO/dPDPN cells, as previously described [15]. After solubilization, we used the
PA tag system for the purification of canine PDPN from cell extracts [42]. Purified proteins were
immobilized on Nunc Maxisorp 96-well immunoplates (Thermo Fisher Scientific) at 1 μg/mL for 30
min. After blocking with SuperBlock T20 Blocking Buffer (Thermo Fisher Scientific), the plates wereincubated with serially diluted serum samples followed by 1:5000 diluted peroxidase-conjugatedanti-dog IgG (Thermo Fisher Scientific). Linear standard curves of P38Bf were generated from 3.9 to
125 ng/mL. The enzymatic reaction was produced with a 1-Step Ultra 3,3′,5,5′-tetramethylbenzidineELISA (Thermo Fisher Scientific). The optical density was measured at 655 nm using an iMark
microplate reader (Bio-Rad Laboratories, Hercules, CA, USA). All measurements were performed intriplicate, and each reaction was conducted at 37 °C with a total sample volume of 50 μL.
2.4. Flow Cytometry
Cells were harvested after a brief exposure to 0.25% trypsin/1 mM ethylenediaminetetraacetic
acid (EDTA; Nacalai Tesque, Inc., Kyoto, Japan). After 3 washes in fluorescence-activated cell sorting(FACS) buffer (phosphate buffered saline (PBS) containing 5% FBS and 0.1% sodium azide), cells
were incubated with 5 μg/mL mouse-canine chimeric anti-dPDPN antibody (P38Bf) for 30 min at 4
°C, followed by 3 washes in FACS buffer and incubation with a 1:800 dilution of Alexa Fluor® 647conjugated anti-dog IgG antibodies (Jackson ImmunoResearch Inc., West Grove, PA, USA) for 30 min

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at 4 °C. Whole molecule dog IgG (Jackson ImmunoResearch) was used as an isotype control. All flow
cytometric analyses were performed with BD FACSverse (BD, Franklin Lakes, NJ, USA) and data
were analyzed using BD FACSuite software (BD, ver. 8.0).
2.5. Evaluation of Antibody-Dependent Cellular Cytotoxicity (ADCC)ADCC was examined using a calcein-acetyoxymethyl (Calcein-AM; Cayman Chemical Co., Ann
Arbor, MI, USA) release assay. Canine lymphokine-activated killer (LAK) cells were prepared byculturing canine peripheral blood mononuclear cells from a healthy beagle dog in the presence of1000 IU/mL of human recombinant interleukin-2 (IL-2) (Novartis, East Hanover, NJ, USA) for 1 week,
as previously reported [36]. CMM2 and KMeC cells were used as target cells. The target cells werelabeled with Calcein-AM for 30 min, washed 3 times with PBS containing 5% FBS, and plated onto
96-well plates at a density of 1 × 104 cells/well. P38Bf or whole molecule dog IgG was added at various
concentrations from 0.01 to 10 μg/mL for 15 min on ice. Next, the LAK cells were added as effector
cells at an effector (E)/target (T) ratio of 10:1. Then, the plates were incubated for 4 h at 37 °C, and therelative light units (RLU) of the supernatants were analyzed using fluorometry to measure calcein
release (cell death). For maximal release, the cells were lysed with 2% Triton X-100. Fluorescence was
detected using the ARVO X4 system (PerkinElmer, Waltham, MA, USA). ADCC activity wascalculated using the following formula:
Cytotoxicity (%) = (test RLU − spontaneous death RLU)/(maximal deathRLU −spontaneous death RLU) × 100.
For each experiment, measurements were conducted in quadruplicate using four replicate wells.
Each experiment was repeated at least 3 times.
2.6. P38Bf Injection into a Healthy Dog
To examine the safety of anti-dPDPN treatment in dogs, P38Bf (2 mg/kg) was intravenously
administrated into one healthy beagle (female, 1.2 years old) once every 2 weeks for a total of four
administrations. The study was approved by the University of Tokyo Animal Care and Use
Committee (P18-021). A thorough physical examination, complete blood count (CBC) (IDEXX
ProCyte Dx, IDEXX Lab., ME, USA), serum chemistry (albumin (ALB), alkaline phosphatase (ALP),
blood urea nitrogen (BUN), calcium (Ca), creatinine (CRE), C-reactive protein (CRP), electrolytes (Na,K, Cl), glomerular filtration rate (GFR), γ-glutamyltransferase (GGT), glucose (GLU), glutamic
oxaloacetic transaminase; glutamic-oxaloacetic transaminase (GOT), glutamic pyruvic transaminase(GPT), total bilirubin (TBIL), total cholesterol (TCHO), triglycerides (TG), total protein (TP), lipase(vLIP), and inorganic phosphorus (iP)) (Fuji DRI-CHEM 7000V, FUJIFILM Co., Tokyo, Japan), andurinalysis (Thinka Urine Test Strip and Urine Analyzer Thinka RT-4010, Arkray Co., Kyoto, Japan)
were performed to determine general health status. To evaluate the acute adverse effects, bodytemperature, heart rate, respiratory rate, and percutaneous oxygen saturation (SpO2) were recorded
at baseline and every 30 min after the administration of P38Bf for 5 h. SpO2 was monitored using a
bedside monitor (LifeScope, NIHON KOHDEN Co., Tokyo, Japan). To evaluate chronic adverse
effects, blood tests were repeated every day for 7 days following antibody administration andrepeated every week thereafter. Body temperature, heart rate, and respiratory rate were monitored
at the same time as the blood test. Since PDPN is expressed in the kidney glomerulus, plasma
clearance of intravenously administered inulin was evaluated for estimating the glomerular filtration
rate to obtain detailed information on kidney function (FUJIFILM Monolith Co). Computed
tomography (CT) was performed to evaluate structural abnormalities in the whole body at the timingof, before 7 days, and after 56 days of antibody administration. Before and after injection of theantibody, concentrations of serum P38Bf were measured by direct ELISA, as mentioned above. The
dog was sacrificed 2 weeks after the last administration for gross necropsy and histopathologicalanalysis. The pathological evaluation was performed by a single veterinary pathologist. Adverse
events were assessed and classified according to the Veterinary Cooperative Oncology Group—
Common Terminology Criteria for Adverse Events (VCOG-CTCAE) v 1.1 criteria [43].

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2.7. Immunohistochemistry
Immunohistochemical staining was performed using primary antibodies specific for dPDPN todetermine the eligibility for enrollment in the clinical trial of P38Bf treatment. All tumor tissues were
fixed in 10% neutral buffered formalin, embedded in paraffin wax, and cut into 4 µm serial sections.
Paraffin-embedded tumor sections were dewaxed and rehydrated in xylene and graded ethanol,
followed by antigen retrieval using 10 mM Tris-HCl 1 mM EDTA buffer pH 9.0 at 100 °C for 30 min
in boiling water. After washing with Tris-buffered saline with 0.1% Tween® 20 (Sigma Chemical Co)
detergent (TBST), endogenous peroxidase was blocked with 3% H2O2 in methanol for 10 min at room
temperature. Then, specimens were washed with TBST and incubated in 8% skim milk for 1 h at room
temperature to reduce nonspecific binding before overnight incubation with primary antibodies,including mouse IgG1 anti-dPDPN mAb (PMab-38) diluted 1:200 at 4 °C in a humidified chamber. A
negative control was incubated with the purified mouse IgG1 κ isotype antibody (Clone: MG1-45,
BioLegend, San Diego, CA, USA) under identical conditions. After washing with TBST, sections wereincubated with a horseradish peroxidase-conjugated anti-mouse antibody (EnVision™+ System, ahorseradish peroxidase (HRP) labeled polymer; K4001; Agilent Technologies, Santa Clara, CA, USA)for 30 min at room temperature. Thereafter, the sections were washed with TBST, incubated with 3,3′
diaminobenzidine (Dojindo Laboratories, Kumamoto, Japan) solution for 3 min, and counterstainedwith Mayer’s hematoxylin. ALP staining was performed in melanoma tissues with numerous
melanin granules. In this method, ALP-conjugated streptavidin (diluted to 1:400; Innova Biosciences,
Cambridge, UK) and an ALP substrate kit (VECTOR Laboratories, Burlingame, CA, USA) were usedin place of HRP-conjugated streptavidin and 3,3′-diaminobenzidine. Sections of canine squamous cell
carcinoma tissues were used as positive controls for dPDPN. The specimens were considered positivefor dPDPN if histological evidence of cell staining was present in five independent high-power (400×magnification) fields.
2.8. Clinical Trial in Dogs with Malignant Tumors
To evaluate the clinical safety and efficacy of P38Bf, a clinical trial was conducted at theVeterinary Medical Center (VMC), University of Tokyo. The study was approved by the Animal Careand Clinical Research Committees of the VMC, University of Tokyo (VMC2018-4). The inclusion
criteria for the clinical trial were dogs with dPDPN positive malignant melanoma and tumors
resistant to standard therapies (e.g., surgery, radiation therapy, and chemotherapy). dPDPN
expression was confirmed by immunohistochemical analysis of the tumor tissues obtained bysurgical excision prior to surgery or biopsy. After written informed consent was obtained from theowners, P38Bf was intravenously administered every 2 weeks at 2 mg/kg, at a rate of 1 mL/min or
below, except for the indicated case. During the treatment period, the dogs were monitored byphysical examination, CBC, and serum chemistry at least every 2 weeks. The monitoring time course
was the same as that of the safety evaluation using a healthy dog (2.4.). The tumor size was measured
using a caliper and recorded every 2 weeks if measurable lesions were present on the body surface.
At baseline (within 2 weeks prior to the first P38Bf administration), the day of the thirdadministration, and 2 weeks after the fourth administration, thoracic radiography or CT were
performed to evaluate the tumor burden in the whole body. The tumor burden was calculated as thesum of the longest diameters of all measurable target lesions. Tumors ≥ 10 mm through the longest
diameter were considered measurable lesions. A maximum of five target lesions were chosen frommeasurable lesions at baseline, with a maximum of two lesions per organ. Tumor response to P38Bf
treatment was defined as follows: complete response (CR) was disappearance of all detectable tumor;
partial response (PR) was at least 30% reduction in the sum of the diameters of target lesions; stabledisease (SD) was less than 20% increase or 30% reduction in the sum of diameters, and progressive
disease (PD) was at least a 20% increase in the sum of diameters. The longest diameters of new
measurable lesions (up to five lesions in total and up to two lesions per organ) were included in thesum. The clinical responses were evaluated for each administration of P38Bf according to response
evaluation criteria for solid tumors (RECIST) in dogs (v1.0) [44]). Adverse events were assessed andCells 2020, 9, 2529

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2.9. Statistics
All data are shown as the mean ± standard error (SE). For the evaluation of ADCC activity,
Tukey–Kramer’s test was performed using R software (ver. 3.6.1, R Development Core Team, 2019).
For the evaluation of acute and chronic adverse effects, a one-way ANOVA test was performed using
R software. Values of p < 0.05 were considered statistically significant.
3. Results
3.1. Antibody-Dependent Cellular Cytotoxicity (ADCC) Induced by a Cancer-Specific Mouse–Dog Chimericanti-PDPN Antibody (P38Bf) against Canine Melanoma Cells
The reactivity of P38Bf against canine podoplanin (dPDPN) expression on the cell surface of
canine melanoma cell lines was evaluated using flow cytometric analysis. Chinese hamster ovary(CHO)-K1 and canine PDPN-expressing CHO-K1 with N-terminal PA tag (CHO/dPDPN) cells wereused as negative and positive controls, respectively. dPDPN expression on CHO/dPDPN, CMM2,
and CMM11 cells were clearly detected by P38Bf (Figure 1A and Figure S1). CHO-K1 cells showedno fluorescence, and KMeC, CMM1, and CMM8 showed low fluorescence intensity (Figure 1B and
Figure S1).

Figure 1. Flow cytometric analysis of CMM2 (A) and KMeC (B) cells treated with isotype control(black line) and a cancer-specific mouse–dog chimeric anti-PDPN antibody (P38Bf) (red line). P38Bf
showed a higher reaction against CMM2 cells compared with KMeC cells. Antibody-DependentCells 2020, 9, 2529

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Cellular Cytotoxicity (ADCC) activity of P38Bf against CMM2 (C) and KMeC cells (D) at various
antibody concentrations determined by calcein release assay show significant ADCC activity against
CMM2 cells in a dose-dependent manner. Values presented are the mean ± SEM. ** p < 0.01.

From the results of the flow cytometric analysis, CMM2 and KMeC were selected as dPDPNhigh and dPDPN-low expressing cells, respectively. Using CMM2 and KMeC cells, the ADCC activity
induced by P38Bf was evaluated. P38Bf showed strong cytotoxicity against CMM2 at antibody
concentrations of 1 and 10 µg/mL compared to the control isotype antibody (p < 0.01, Figure 1C). In
contrast, no significant ADCC activity of P38Bf was measured in KMec cells (Figure 1D).
3.2. Safety and Toxicity of P38Bf
As P38Bf showed significant in vitro anti-tumor activity, we next evaluated the detailed adverse
effects of P38Bf in an experimental healthy beagle dog. P38Bf (2.0 mg/dog) was intravenously injected
into a healthy beagle dog once every 2 weeks for a total of four administrations. The maximum
plasma concentration of P38Bf was 23.09 µg/mL and P38Bf was detected even after 168 h (4.72 µg/mL)of administration (Figure S2). After 336 h of P38Bf administration, P38Bf was no longer detectable in
the plasma (below detection threshold of 3.9 µg/mL).
Acute adverse effects were evaluated at each administration (4 times) for 5 h after P38Bf
administration. Body temperature (mean: 38.6 °C, range: 37.8–39.3 °C), heart rate (mean: 96/min,range: 84–108/min), respiratory rate (mean: 18/min, range: 12–24/min), and percutaneous oxygen
saturation (SpO2) (mean: 99%, range: 97–100%) were within normal range during the 5 h period(Figure S3). Chronic adverse effects were evaluated for 8 weeks after the P38Bf administration byphysical tests (body temperature, heart rate, respiratory rate, and SpO 2) and blood tests (complete
blood count (CBC), albumin (ALB), alkaline phosphatase (ALP), blood urea nitrogen (BUN), calcium(Ca), creatinine (CRE), C-reactive protein (CRP), electrolytes (Na, K, Cl), glomerular filtration rate
(GFR), γ-glutamyltransferase (GGT), glucose (GLU), glutamic oxaloacetic transaminase; glutamicoxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT)), total bilirubin (TBIL), totalcholesterol TCHO), triglycerides (TG), total protein (TP), lipase (vLIP), inorganic phosphorus (iP)).
All evaluated parameters were within the normal range during the observation period (Figure S4 andTable S1). Body weight did not change substantially (mean: 9.8 kg, range: 9.4–10.3 kg) (Figure S4). No
abnormal changes were found by urinalysis (data not shown). After 56 days of antibody
administration, computed tomography (CT) examination was performed to evaluate organic changes
by P38Bf between pre-first administration and post-last administration, and there was no detectablechange including inflammation or necrosis in systemic organs (Movie S1 (pre-first) and S2 (postlast)). After 8 weeks of administration, the dog was euthanized, and adverse histological effects ineach organ were evaluated, including kidney, lung, small intestine, stomach, bladder, spleen, bonemarrow, and lymph node. No adverse events or abnormalities in histological findings were found in
the systemic organs (Figure S5).
Following the data of the preclinical study using the experimental healthy dog, we conducted aphase I/II clinical trial for the evaluation of clinical safety and potential efficacy of anti-PDPN
antibody therapy in dogs with dPDPN-positive malignant melanoma. Three dogs with malignant
melanoma that diffusely expressed dPDPN were enrolled in the clinical trial, and the clinicalcharacteristics of each dog are shown in Table 1. The representative images of dPDPN expression ineach tumor tissue are shown in Figure S6. Breeds of included dogs were mixed breed, miniaturedachshund, and beagle, respectively, and their ages ranged from 13.7 to 14.8 years (median: 14.7
years) at the time of enrollment. All dogs were resistant to conventional therapies including surgery,chemotherapy, and radiation therapy. Detailed clinical histories of each case are summarized in Table
1. The dogs were intravenously injected with P38Bf at 2 mg/kg. Dog#2 received 4 injections of P38Bf
with a two-week interval, except for the fourth administration, which was performed 3 weeks after
the third administration for reasons pertaining to the owner. Dog#1 and #3 received a single
administration.

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Table 1. Characteristics of dogs treated with P38Bf.

Case #Breed

Age(Years)

1

Mix

14.7

2

Miniaturedachshund

13.7

3

Beagle

14.8

Sex
Male,
castrated
Female,spayedMale

Body
Weight (kg)
15.5
4.9
11

Diagnosis
Malignantmelanoma
Malignantmelanoma
Malignantmelanoma(amelanotic)

Primary Site

WHO
Stage

Prior Therapy

TongueIV

Surgery, radiation,
chemotherapy

Hard plate

III

Surgery

Gingiva

I

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For the evaluation of acute adverse effects, changes in body temperature, heart rate, andrespiratory rate were monitored for up to 3 h after the intravenous administration of P38Bf. Body
temperature (mean: 38.3 °C, range: 37.6–39.4 °C), heart rate (mean: 118/min, range: 57–152/min), andrespiratory rate (mean: 21/min, range: 16–32/min) were within the normal range during the 3 hperiod, and there was no significant change (Figure 2A–C). Since grade 2 vomiting was observed indog#2 within 3 h of administration, maropitant (1 mg/kg, s.c.) was administered as an anti-emetic
drug (Table 2). Vomiting could be controlled by a single anti-emetic drug administration, andtreatment was not withdrawn. On the day after the first administration, the observed treatmentrelated adverse events were all grade 1 or 2 and did not cause treatment withdrawal. During theobservation period, chronic adverse effects were evaluated, including the monitoring of symptoms,
physical tests, and blood tests. The evaluated parameters showed no significant change orabnormality except for CRP increase in the blood chemistry tests of all dogs (Table 2 and Figure S7).
All dogs showed mild CRP increases without any symptoms. The maximum of the CRP level ofdog#1 was 7.0 pg/mL. The maximum of the CRP level of dog#2 was also 7.0 pg/mL at 70 days after
antibody administration. After 70 days, the CRP level gradually decreased, and the CRP level was
4.2 pg/mL at 84 days after antibody administration. The maximum of the CRP level of dog#3 was also
7.0 pg/mL after 8 days of antibody administration, and the CRP level was 0.8 pg/mL at 14 days after
antibody administration.

Figure 2. Evaluation of acute adverse effects of P38Bf administration in three dogs. Effects of P38Bf
administration on body temperature (A), heart rate (B) and respiratory rate (C). Each dot represents
an individual subject at one P38Bf administration and horizontal bars indicate the mean value for all
patients at each time point. Significant changes in each parameter were not observed. One-way
ANOVA test was performed and p values were 0.77, 0.98, and 0.85, respectively.
Table 2. Treatment-related adverse events of P38Bf administration.

EventsGeneral disorders
Vomiting
Biochemical parameters
Increased CRP

Number of Cases
Grade 3
Grade 4

Grade 1

Grade 2

0

1

0

3

0

0

Grade 5

Total

0

0

1

0

0

3

3.3. Clinical Response of P38Bf
The overall responses were stable disease (SD) in one dog (#3) and progressive disease (PD) in
two dogs (#1 and #2) (Table 3).

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Table 3. Results of dogs treated with P38Bf.

Case #

Dosage12
3

2 mg/kg
2 mg/kg
2 mg/kg

Times Given
P38Bf
1
4
1

Treatment
Duration
2 weeks
9 weeks
2 weeks

Best overall
Response
PD *
PD
SD

* Part of the lesion showed growth inhibition.

Dog#1 was categorized as WHO stage IV and had metastatic lesions in the lung and skin, which
expanded rapidly even with some conventional therapies before inclusion in this clinical trial. The
primary tumor in the oral cavity was a microscopic lesion after palliative surgery and was notmeasurable during the evaluated period. Dog#1 showed a new metastatic tumor lesion in the skinafter 7 days of antibody administration and was diagnosed with PD. Four lesions of skin metastasis
existed before inclusion in the study. Tumor growth of one lesion in skin was stopped, and one lesionin skin was decreased after P38Bf administration (Figure 3A). Although part of the lung metastasis
showed growth inhibition, the majority of the metastatic lesions of the lung tended to develop evenafter P38Bf administration (Figure S8).

Figure 3. Evaluation of P38Bf efficiency in the clinical trial. Measurement and evaluation of the skinmetastasis of Dog #1 (A), the oral primary tumor of Dog#2 (B), and the oral primary tumor of Dog#3(C). The tumor burden of Dog#1, Dog#2, and Dog#3 was evaluated by measuring the diameter of theCells 2020, 9, 2529

11 of 19long axis. The day of first antibody administration is shown as Day 0, and black arrows indicate thetiming of P38Bf administration.

Dog#2 was categorized as WHO stage Ш and had a 31.1 mm primary tumor in the oral cavity
without metastatic lesions. The long axis diameter of the primary tumor in the oral cavity wasmeasured using a CT exam at the day of antibody administration and after 49 days of antibody
administration. Dog#2 received antibody administration four times. Although the metastatic lesion
was not detected during the observation period, 49 days after first administration, the tumor diameter
had increased by about 40% compared to the time of first administration (Figure 3B and Figure S9).
Thus, dog#2 was categorized as PD.
Dog#3 was categorized as WHO stage I and had a 13.5 mm primary tumor in the oral cavity
without metastatic lesions. The long diameter of the primary tumor in the oral cavity was measured.
Dog#3 was categorized as SD because the tumor burden of the primary tumor increased by less than
20%, and new metastatic lesions were not detected during the observation period (Figure 3C). Thelong diameter increased by only 2% and 8% at 2 and 4 weeks after P38Bf administration, respectively,
compared to the time of first administration, although it increased by 14% during the 2 weeks before
P38Bf administration.
4. Discussion
This is the first report of a clinical trial using anti-podoplanin (PDPN) mAb in canine models.
We first demonstrated that a cancer-specific mouse–dog chimeric anti-PDPN antibody (P38Bf)
induces antibody-dependent cellular cytotoxicity (ADCC) by recognizing endogenously expressedcanine podoplanin (dPDPN) on canine malignant melanoma cells. In this clinical trial, we evaluatedthe acute and chronic adverse effects of P38Bf in one healthy experimental dog and three dogs withcanine malignant melanoma, and we did not find any serious adverse effects during the experimental
periods. Furthermore, P38Bf might have delayed tumor growth in several dogs.
In this study, the reactivity and ADCC of P38Bf were evaluated using canine malignant
melanoma cell lines. This study targets canine malignant melanoma because it was reported that 80%
of canine malignant melanomas express dPDPN on tumor cells [18,45]. P38Bf clearly recognizedendogenously expressed dPDPN on canine malignant melanoma cell lines and showed significant
and dose-dependent ADCC activity on CMM2 at antibody concentrations of 1 and 10 µg/mL. The
specificity of ADCC activity against dPDPN expression induced by P38Bf was originallydemonstrated using anine PDPN-expressing chinese hamster ovary (CHO)-K1 with N-terminal PA
tag (CHO/dPDPN) cells (dPDPN overexpressing cells) and CHO-K1 cells (dPDPN negative cells)[36], and therefore, these cell lines were included in the current study as positive and negative
controls. [36]. Therefore, it is suggested that an induction of ADCC against CMM2 was specific todPDPN expression, and the Fc region of P38Bf significantly activated canine natural killer (NK) cells
in a target antibody-dependent manner. However, ADCC was not induced against KMeC cells,
although KMeC cells were weakly recognized by P38Bf. It was reported that the lack of sufficientantigen density on target cells and insufficient antibody–antigen density lead to insufficient ADCC
[46–48]. Since dPDPN expression on KMeC cells was weaker than that of CMM2, it was consideredthat dPDPN expression on KMeC cells was not sufficient to induce ADCC by P38Bf and canine
natural killer (NK) cells. These results indicated that P38Bf could recognize dPDPN expressed on
canine tumor cells at the endogenous expression level and induce ADCC against dPDPN positive
canine malignant melanoma.
A preclinical safety trial was performed using only one healthy beagle dog due to animal ethics.
Since immunological adverse effects against injected antibodies derived from other species have beenreported, chimeric antibodies have been developed and have successfully inhibited immunologicaladverse effects in human medicine (e.g., Rituximab) [49,50]. Based on these reports, in this study, weused mouse-canine chimeric anti-dPDPN antibody to suppress immunological adverse effects indogs. Even when injected antibodies were chimeric antibodies, some reports described chimericantibody-related infusion reactions, which are acute adverse effects and often occur within 30 min toCells 2020, 9, 2529

12 of 192 h after administration [49–52]. Common symptoms and signs are dyspnea, nausea, headache, andabdominal pain [49–52]. Most reactions were reported to be mild, and it was also reported that only
approximately 0.3% of patients have serious infusion reactions with features of anaphylaxis(bronchospasm, hypotension, and angioedema) [49–52]. In this preclinical safety trial, we carefully
evaluated acute adverse effects after four injections of the antibody for 5 h after antibody
administration in one experimental beagle dog. There were no symptomatic acute adverse effects oranaphylaxis signs, including abnormality of circulation and respiration (i.e., body temperature, heartrate, respiratory rate, and percutaneous oxygen saturation (SpO2)). These findings indicate that theminimum safety of the infusion reaction with P38Bf. Since the rate of infusion-related adverse effects
varies among different monoclonal antibodies (rituximab: 77%; trastuzumab: 40%; cetuximab: 15%–20%; bevacizumab: <3%; and panitumumab: 3%) [53], the rate of infusion-related reactions inducedby P38Bf administration should be investigated in a large-scale clinical trial.
Considering the chronic adverse effects caused by on-target/off-tumor cytotoxity, no obvious
chronic adverse effects were observed by physical examination, blood tests, urinary analysis,computed tomography (CT) analysis, or histopathological analysis in this preclinical safety trial. We
hypothesize several mechanisms for the expropriation of this phenomenon. First, P38Bf recognizes
dPDPN expressed on tumor cells but not on normal cells. Since PDPN is a glycoprotein that causes
tumor-specific aberrant glycosylation in tumor cells [17,31], a cancer-specific anti-PDPN antibody
could specifically recognize cancer-specific aberrant glycosylation. P38Bf was designed to recognize
only dPDPN expressed on tumor cells but not dPDPN expressed in normal tissues by recognizing
cancer-specific aberrant glycosylation [17,36]. In fact, although it has been reported that dPDPN isexpressed in various normal tissues, including the kidney, lung, and lymphatic vessels, PMab-38, theoriginal form of P38Bf, did not recognize dPDPN expression in any canine normal tissues [17].
Second, P38Bf might recognize dPDPN expressed on tumor cells and normal cells, but ADCC wasonly induced against tumor cells that overexpressed dPDPN due to sufficient antibody density. We
previously reported that the expression density of dPDPN in tumor cells was stronger than that on
normal cells [17]. In addition, it was demonstrated that P38Bf could induce ADCC in dPDPN highexpression canine melanoma cells but not against dPDPN low-expression canine melanoma cells. As
another possible mechanism, P38Bf might recognize dPDPN expressed on tumor cells and normal
cells, but NK cells were not able to infiltrate into normal tissues and therefore could not be activatedthere. This hypothesis is supported by many reports that have demonstrated that more NK cells weregathered and activated in canine and human melanoma tissues compared to normal tissues [54]. In
this study, we could not clarify the specific mechanism of this phenomenon, and further evaluationis needed.
In the phase I/II clinical trial, three dogs with malignant melanoma were included in this study.
Canine melanoma is the most common tumor in canine oral tumors. It accounts for 3% of all
neoplasms and up to 7% of all malignant tumors [55–58]. Generally, complete surgical removal is
performed for the management of local tumor control, but almost all dogs with advanced melanoma
will progress to lung and lymph node metastasis and death within one year because of resistance tochemotherapy and radiotherapy [55–58]. A new and effective therapeutic approach for canine
malignant melanoma is required. We conducted a phase I/II clinical trial to evaluate the clinical safety
and potential efficacy of P38Bf. All treatment-related acute and chronic adverse events were grade 1
or 2 out of 5. Although the acute adverse effect of grade 2 vomiting was observed in one dog, vomiting
was transient and manageable with anti-emetic treatment alone. In humans, grade 1–2 nausea andvomiting are common adverse events with antibody-based therapy, occurring in 9.7–33% of patients
given trastuzumab, and most events were manageable with symptomatic treatments [59–61].
Vomiting induced by P38Bf would also be tolerable and manageable in a clinical setting, and it isconsidered that vomiting induced by P38Bf is not sufficiently serious to withdraw the clinical trial.
In this study, C-reactive protein (CRP), a marker of systemic inflammation, increased mildly in all
dogs. CRP is a substance produced by the liver in response to inflammation and is often used as an
inflammatory marker [62]. CRP increase was often observed as immune-related adverse events; it
has also been reported that approximately 20% of patients show tissue inflammation after rituximab

Cells 2020, 9, 2529

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injection [63,64]. This tissue inflammation is called serum sickness, which is a delayed type 3 allergic
reaction against chimeric antibodies, and the reaction typically develops one to two weeks after
treatment [50,53,64,65]. The increase in CRP in all dogs indicates the occurrence of inflammation due
to disease progression, antibody-induced antitumor responses, and/or serum sickness induced by
P38Bf injection. We could not completely elucidate the specific cause of CRP increase at this time. In
any case, there were no severe treatment-related adverse effects that required withdrawal of theantibody administration in this study, promoting a further investigation of large clinical trials toevaluate the efficacy and safety of P38Bf.
In this study, the responses to P38Bf administration were stable disease (SD) in one dog andprogressive disease (PD) in two dogs. Although one dog (#1) with melanoma that was categorized as
WHO stage IV had PD, a few metastatic skin lesions ceased rapid growth after the administration of
P38Bf. A previous study has reported that PDPN is related to tumor invasion and metastasis, and it
was also reported that the PDPN expression density of tumor cell lines derived from metastatic
lesions was higher than that of the primary tumor [66]. In this case, it is possible that the difference
in responses among metastatic lesions might have caused heterogeneity in PDPN expression density.
The clinical response of dog#3, categorized as WHO stage I, was SD. It is well known that the efficacy
of cytotoxic antibodies depends on the number of tumor-infiltrating effector cells (e.g., NK cells,
macrophages), and cytotoxic antibodies show stronger anti-tumor effects against tumors with alarger number of infiltrating effector cells [67,68]. In canine malignant melanoma, the number of
infiltrating effector cells is inversely correlated with tumor stage [69]. It is possible that P38Bf showedslight anti-tumor effects against the dog with stage I malignant melanoma because the efficacy ofP38Bf also depends on the number of tumor-infiltrating effector cells. Further investigation into theclinical efficacy of P38Bf in dogs with malignant tumors and the factors that affect the efficacy ofP38Bf are needed.
In recent years, new strategies using antibodies, such as antibody–drug conjugate (ADC) andchimeric antigen receptor (CAR) T-cell therapy, have been developed to improve anti-tumor effects.
ADC are antibodies connected with anti-tumor cytotoxic molecules that can specifically kill the target
cells by a specific linkage, such as trastuzumab-emtansine targeting human epidermal growth factor
receptor type2 positive tumors [70,71]. CAR T-cells consist of a single-chain Fab of antibody and T
cells and eliminate target cells by cytotoxic T-cell function, such as CD19 CAR-T cell therapy targeting
lymphoma and leukemia [72–74]. Recently, CAR-T cells targeting PDPN were reported, and antiPDPN CAR-T cells demonstrated strong anti-tumor effects in orthotopic glioblastomas of the mousebrain [75]. Although P38Bf was safely administered to the four dogs, strong anti-tumor effects by
P38Bf were not observed in the phase I/II clinical trial. The anti-PDPN therapy based on ADC and
CAR-T strategies would improve the anti-tumor effects of P38Bf.
The limitation of this study was the small sample size. In this study, a total of four dogs wereadministered P38Bf, but this number was not sufficient for a full evaluation of safety. Antibody
concentration was specified as 2.0 mg/kg in this study. Appropriate antibody concentrations shouldbe optimized in further clinical trials. A long-term administration of P38Bf and long-term observation
in a large clinical cohort would elucidate the detailed clinical efficacy and safety.
In this study, the efficacy and safety of the cancer-specific anti-canine PDPN chimeric antibody,
P38Bf, was evaluated. In the in vitro experiment, our findings suggested that P38Bf has strong ADCC
activity and anti-tumor effects against dPDPN expressing canine melanoma cells. A preclinical safety
trial and phase I/II clinical trial suggested that P38Bf could be safely administered without severe
adverse events, although the observed clinical response was only a potential anti-tumor effect.
Further investigation for large clinical trials is needed to clarify the efficacy and safety of P38Bf.
Supplementary Materials: The following are available online at www.mdpi.com/2073-4409/9/11/2529/s1, Figure
S1: Evaluation of dPDPN expression on canine malignant melanoma cell lines by flow cytometric analysis;
Figure S2: Kinetic of P38Bf in blood serum in one healthy dog; Figure S3: Evaluation of acute adverse effects of
P38Bf administration in one healthy dog; Figure S4: Evaluation of chronic adverse effect of P38Bf administrationin one healthy dog; Figure S5: Whole body histopathological evaluation of chronic adverse effects of P38Bf
administration; Figure S6: Representative images of immunohistochemistry for dPDPN in oral malignant
melanomas of three cases; Figure S7: Serum CRP levels of three cases before and after administration of P38Bf;

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Figure S8: Radiographic evaluation of lung metastasis of Dog#1; Figure S9: Computed tomographic evaluationof the primary tumor at oral cavity of Dog#2; Table S1: Detailed results of the blood tests of one healthy dog;
Video S1: Whole body computed tomographic examination at the time of pre-first P38Bf administration in one
healthy dog; Video S2: Whole body computed tomographic examination at the time of post-last P38Bf
administration in one healthy dog; Supplemental text file: The figure legends of supplemental figure 1 to 9.
Author Contributions: S.K., D.K., R.N. and T.N. conceived and designed the study. S.K., M.S., D.K., Y.H. and
Y.T. performed the experiments. S.K., M.S., D.K., S.Y., N.I., M.T., R.Y., S.E., Y.H., Y.T., J.C., K.U., M.K.K. and N.F.
analyzed the data. S.K., M.S. and D.K. wrote the paper. R.N., Y.K., and D.K. acquired the funding. D.K., R.N.
and T.N. supervised the study. All authors contributed to manuscript revision and read and approved thesubmitted version. All authors have read and agreed to the published version of the manuscript.
Funding: This research was supported in part by AMED (grant numbers: JP20am0401013 (Y.K.), JP20am0101078(Y.K.), and JP20ae0101028 (Y.K.), and JSPS KAKENHI [grant numbers: 19K22361 (RN), 19K23705 (DK), and
20H03141 (DK)].
Acknowledgments: We are grateful to the staff at VMC, The University of Tokyo for support of this study.
Conflicts of Interest: The authors declare no conflicts of interest. The funders had no role in the design of thestudy; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to
publish the results.

Abbreviations(PDPN)(CAFs)(EMT)(ADCC)(CHO)(CasMab)(dPDPN)(mAb)(P38Bf)(FBS)(PSA)(CHO/dPDPN)(IgG)(ELISA)(FACS)(PBS)(LAK)(IL-2)
(RLU)
(CBC)
(ALB)
(ALP)
(BUN)
(Ca)
(CRE)
(CRP)
(Na, K, Cl)
(GFR)
(GGT)
(GLU)
(GOT)
(GPT)
(TBIL)

podoplanincancer-associated fibroblasts
epithelial-mesenchymal transition
antibody-dependent cellular cytotoxic
chinese hamster ovary
cancer-specific monoclonal antibody
canine PDPN
monoclonal antibody
a cancer-specific mouse–dog chimeric anti-PDPN antibody
fetal bovine serum
penicillin, streptomycin, and amphotericin B
canine PDPN-expressing CHO-K1 with N-terminal PA tag
immunoglobulin G
enzyme-linked immunosorbent assay
fluorescence-activated cell sorting
phosphate buffered saline
lymphokine-activated killer
interleukin-2
relative light units
complete blood countalbuminalkaline phosphatase
blood urea nitrogencalcium
creatininec-reactive protein
electrolytes
glomerular filtration rate
γ-glutamyltransferase
glucoseglutamic oxaloacetic transaminase; glutamic-oxaloacetic transaminase
glutamic pyruvic transaminase
total bilirubinCells 2020, 9, 2529

(TCHO)(TG)(TP)(vLIP)(iP)(SpO2)(CT)(VCOG-CTCAE)(TBST)(VMC)(RECIST)
(SE)
(CR)
(PR)
(SD)
(PD)
(NK)
(ADC)
(CAR)

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total cholesterol
triglycerides
total protein
lipaseinorganic phosphorus
percutaneous oxygen saturation
computed tomography
Veterinary Cooperative Oncology Group—Common Terminology Criteria
for Adverse Eventstris-buffered saline with 0.1% Tween® 20 detergent
Veterinary Medical Center
response evaluation criteria for solid tumors
standard error
complete response
partial response
stable diseaseprogressive diseasenatural killer
Antibody–drug conjugate
chimeric antigen receptor

References
1.
2.

3.

4.

5.

6.

7.
8.

9.

10.

11.

Quintanilla, M.; Montero, L.M.; Renart, J.; Villar, E.M. Podoplanin in inflammation and cancer. Int. J. Mol.
Sci. 2019, 20, 707, doi:10.3390/ijms20030707.
Krishnan, H.; Rayes, J.; Miyashita, T.; Ishii, G.; Retzbach, E.P.; Sheehan, S.A.; Takemoto, A.; Chang, Y.W.;
Yoneda, K.; Asai, J.; et al. Podoplanin: An emerging cancer biomarker and therapeutic target. Cancer Sci.
2018, 109, 1292–1299, doi:10.1111/cas.13580.
Zimmer, G.; Oeffner, F.; Von Messling, V.; Tschernig, T.; Gröne, H.J.; Klenk, H.D.; Herrler, G. Cloning andcharacterization of gp36, a human mucin-type glycoprotein preferentially expressed in vascularendothelium. Biochem. J. 1999, 341, 277–284, doi:10.1042/0264-6021:3410277.
Breiteneder-Geleff, S.; Matsui, K.; Soleiman, A.; Meraner, P.; Poczewski, H.; Kalt, R.; Schaffner, G.;
Kerjaschki, D. Podoplanin, novel 43-kd membrane protein of glomerular epithelial cells, is down-regulated
in puromycin nephrosis. Am. J. Pathol. 1997, 151, 1141–1152.
Martín-Villar, E.; Scholl, F.G.; Gamallo, C.; Yurrita, M.M.; Muñoz-Guerra, M.; Cruces, J.; Quintanilla, M.
Characterization of human PA2.26 antigen (T1α-2, podoplanin), a small membrane mucin induced in oral
squamous cell carcinomas. Int. J. Cancer 2005, 113, 899–910, doi:10.1002/ijc.20656.
Mishima, K.; Kato, Y.; Kaneko, M.K.; Nishikawa, R.; Hirose, T.; Matsutani, M. Increased expression of
podoplanin in malignant astrocytic tumors as a novel molecular marker of malignant progression. Acta
Neuropathol. 2006, 111, 483–488, doi:10.1007/s00401-006-0063-y.
Ordóñez, N.G. D2-40 and podoplanin are highly specific and sensitive immunohistochemical markers ofepithelioid malignant mesothelioma. Hum. Pathol. 2005, 36, 372–380, doi:10.1016/j.humpath.2005.01.019.
Kato, Y.; Kaneko, M.K.; Kuno, A.; Uchiyama, N.; Amano, K.; Chiba, Y.; Hasegawa, Y.; Hirabayashi, J.;
Narimatsu, H.; Mishima, K.; et al. Inhibition of tumor cell-induced platelet aggregation using a novel antipodoplanin antibody reacting with its platelet-aggregation-stimulating domain. Biochem. Biophys. Res.
Commun. 2006, 349, 1301–1307, doi:10.1016/j.bbrc.2006.08.171.
Ariizumi, T.; Ogose, A.; Kawashima, H.; Hotta, T.; Li, G.; Xu, Y.; Umezu, H.; Sugai, M.; Endo, N. Expressionof podoplanin in human bone and bone tumors: New marker of osteogenic and chondrogenic bone tumors.
Pathol. Int. 2010, 60, 193–202, doi:10.1111/j.1440-1827.2009.02510.x.
Marks, A.; Sutherland, D.R.; Bailey, D.; Iglesias, J.; Law, J.; Lei, M.; Yeger, H.; Banerjee, D.; Baumal, R.
Characterization and distribution of an oncofetal antigen (M2A antigen) expressed on testicular germ celltumours. Br. J. Cancer 1999, 80, 569–578, doi:10.1038/sj.bjc.6690393.
Kitano, H.; Kageyama, S.I.; Hewitt, S.M.; Hayashi, R.; Doki, Y.; Ozaki, Y.; Fujino, S.; Takikita, M.; Kubo, H.;
Fukuoka, J. Podoplanin expression in cancerous stroma induces lymphangiogenesis and predicts

Cells 2020, 9, 2529

12.

13.

14.
15.

16.

17.

18.

19.

20.

21.
22.

23.
24.
25.

26.

27.
28.

29.

16 of 19

lymphatic spread and patient survival. Arch. Pathol. Lab. Med. 2010, 134, 1520–1527, doi:10.1043/2009-0114OA.1.
Schoppmann, S.F.; Berghoff, A.; Dinhof, C.; Jakesz, R.; Gnant, M.; Dubsky, P.; Jesch, B.; Heinzl, H.; Birner,
P. Podoplanin-expressing cancer-associated fibroblasts are associated with poor prognosis in invasive
breast cancer. Breast Cancer Res. Treat. 2012, 134, 237–244, doi:10.1007/s10549-012-1984-x.
Kan, S.; Konishi, E.; Arita, T.; Ikemoto, C.; Takenaka, H.; Yanagisawa, A.; Katoh, N.; Asai, J. Podoplanin
expression in cancer-associated fibroblasts predicts aggressive behavior in melanoma. J. Cutan. Pathol. 2014,
41, 561–567, doi:10.1111/cup.12322.
Yamada, S.; Itai, S.; Kaneko, M.K.; Kato, Y. PMab-48 Recognizes Dog Podoplanin of Lymphatic Endothelial
Cells. Monoclon. Antib. Immunodiagn. Immunother. 2018, 37, 63–66, doi:10.1089/mab.2017.0053.
Honma, R.; Kaneko, M.K.; Ogasawara, S.; Fujii, Y.; Konnai, S.; Takagi, M.; Kato, Y. Specific Detection of
Dog Podoplanin Expressed in Renal Glomerulus by a Novel Monoclonal Antibody PMab-38 in
Immunohistochemistry.
Monoclon.
Antib.
Immunodiagn.
Immunother.
2016,
35,
212–216,
doi:10.1089/mab.2016.0022.
Kaneko, M.K.; Honma, R.; Ogasawara, S.; Fujii, Y.; Nakamura, T.; Saidoh, N.; Takagi, M.; Kagawa, Y.;
Konnai, S.; Kato, Y. PMab-38 Recognizes Canine Podoplanin of Squamous Cell Carcinomas. Monoclon.
Antib. Immunodiagn. Immunother. 2016, 35, 263–266, doi:10.1089/mab.2016.0036.
Kiname, K.; Yoshimoto, S.; Kato, D.; Tsuboi, M.; Tanaka, Y.; Yoshitake, R.; Eto, S.; Shinada, M.; Chambers,J.; Saeki, K.; et al. Evaluation of immunohistochemical staining with PMab-38, an anti-dog podoplanin
monoclonal antibody, in various canine tumor tissues. Jpn. J. Vet. Res. 2019, 67, 25–34,
doi:10.14943/jjvr.67.1.25.
Shinada, M.; Kato, D.; Kamoto, S.; Yoshimoto, S.; Tsuboi, M.; Yoshitake, R.; Eto, S.; Ikeda, N.; Saeki, K.;
Hashimoto, Y.; et al. PDPN Is Expressed in Various Types of Canine Tumors and Its Silencing Induces
Apoptosis and Cell Cycle Arrest in Canine Malignant Melanoma. Cells 2020, 9, 1136,
doi:10.3390/cells9051136.
Martín-Villar, E.; Megías, D.; Castel, S.; Yurrita, M.M.; Vilaró, S.; Quintanilla, M. Podoplanin binds ERM
proteins to activate RhoA and promote epithelial-mesenchymal transition. J. Cell Sci. 2006, 119, 4541–4553,
doi:10.1242/jcs.03218.
Wicki, A.; Lehembre, F.; Wick, N.; Hantusch, B.; Kerjaschki, D.; Christofori, G. Tumor invasion in theabsence of epithelial-mesenchymal transition: Podoplanin-mediated remodeling of the actin cytoskeleton.
Cancer Cell 2006, 9, 261–272, doi:10.1016/j.ccr.2006.03.010.
Miyata, K.; Takemoto, A.; Okumura, S.; Nishio, M.; Fujita, N. Podoplanin enhances lung cancer cell growthin vivo by inducing platelet aggregation. Sci. Rep. 2017, 7, 4059, doi:10.1038/s41598-017-04324-1.
Sun, L.; Zhang, L.; Yu, J.; Zhang, Y.; Pang, X.; Ma, C.; Shen, M.; Ruan, S.; Wasan, H.S.; Qiu, S. Clinicalefficacy and safety of anti-PD-1/PD-L1 inhibitors for the treatment of advanced or metastatic cancer: A
systematic review and meta-analysis. Sci. Rep. 2020, 10, 2083, doi:10.1038/s41598-020-58674-4.
Dougan, M.; Dranoff, G.; Dougan, S.K. Cancer immunotherapy: Beyond checkpoint blockade. Annu. Rev.
Cancer Biol. 2019, 3, 55–75, doi:10.1146/annurev-cancerbio-030518-055552.
Lu, R.M.; Hwang, Y.C.; Liu, I.J.; Lee, C.C.; Tsai, H.Z.; Li, H.J.; Wu, H.C. Development of therapeutic
antibodies for the treatment of diseases. J. Biomed. Sci. 2020, 27, 1, doi:10.1186/s12929-019-0592-z.
Esfahani, K.; Roudaia, L.; Buhlaiga, N.; Del Rincon, S.V.; Papneja, N.; Miller, W.H. A review of cancer
immunotherapy: From the past, to the present, to the future. Curr. Oncol. 2020, 27, 87–97,
doi:10.3747/co.27.5223.
Lee, S.; Lee, H.; Kim, E.Y. Comparative Efficacy and Safety of Biosimilar Rituximab and Originator
Rituximab in Rheumatoid Arthritis and Non-Hodgkin’s Lymphoma: A Systematic Review and Metaanalysis. BioDrugs 2019, 33, 469–483, doi:10.1007/s40259-019-00376-z.
Pondé, N.; Aftimos, P.; Piccart, M. Antibody-Drug Conjugates in Breast Cancer: A Comprehensive Review.
Curr. Treat. Options Oncol. 2019, 20, 37, doi:10.1007/s11864-019-0633-6.
Takagi, S.; Sato, S.; Oh-hara, T.; Takami, M.; Koike, S.; Mishima, Y.; Hatake, K.; Fujita, N. Platelets Promote
Tumor Growth and Metastasis via Direct Interaction between Aggrus/Podoplanin and CLEC-2. PLoS ONE
2013, 8, e73609, doi:10.1371/journal.pone.0073609.
Xu, M.; Wang, X.; Pan, Y.; Zhao, X.; Yan, B.; Ruan, C.; Xia, L.; Zhao, Y. Blocking podoplanin suppresses
growth and pulmonary metastasis of human malignant melanoma. BMC Cancer 2019, 19, 599,
doi:10.1186/s12885-019-5808-9.

Cells 2020, 9, 2529

30.

31.
32.

33.
34.
35.
36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

46.

47.

17 of 19

Abe, S.; Kaneko, M.K.; Tsuchihashi, Y.; Izumi, T.; Ogasawara, S.; Okada, N.; Sato, C.; Tobiume, M.; Otsuka,
K.; Miyamoto, L.; et al. Antitumor effect of novel anti-podoplanin antibody NZ-12 against malignant
pleural mesothelioma in an orthotopic xenograft model. Cancer Sci. 2016, 107, 1198–1205,
doi:10.1111/cas.12985.
Kato, Y.; Kaneko, M.K. A cancer-specific monoclonal antibody recognizes the aberrantly glycosylated
podoplanin. Sci. Rep. 2014, 4, 5924, doi:10.1038/srep05924.
Kaneko, M.K.; Yamada, S.; Nakamura, T.; Abe, S.; Nishioka, Y.; Kunita, A.; Fukayama, M.; Fujii, Y.;
Ogasawara, S.; Kato, Y. Antitumor activity of chLpMab-2, a human–mouse chimeric cancer-specificantihuman podoplanin antibody, via antibody-dependent cellular cytotoxicity. Cancer Med. 2017, 6, 768–
777, doi:10.1002/cam4.1049.
Thamm, D.H. Canine Cancer: Strategies in Experimental Therapeutics. Front. Oncol. 2019, 9, 1257,
doi:10.3389/fonc.2019.01257.
Pinho, S.S.; Carvalho, S.; Cabral, J.; Reis, C.A.; Gärtner, F. Canine tumors: A spontaneous animal model ofhuman carcinogenesis. Transl. Res. 2012, 159, 165–172, doi:10.1016/j.trsl.2011.11.005.
Rowell, J.L.; McCarthy, D.O.; Alvarez, C.E. Dog models of naturally occurring cancer. Trends Mol. Med.
2011, 17, 380–388, doi:10.1016/j.molmed.2011.02.004.
Kato, Y.; Mizuno, T.; Yamada, S.; Nakamura, T.; Itai, S.; Yanaka, M.; Sano, M.; Kaneko, M.K. Establishmentof P38Bf, a Core-Fucose-Deficient Mouse-Canine Chimeric Antibody Against Dog Podoplanin. Monoclon.
Antib. Immunodiagn. Immunother. 2018, 37, 218–223, doi:10.1089/mab.2018.0035.
Kato, Y.; Ohishi, T.; Kawada, M.; Maekawa, N.; Konnai, S.; Itai, S.; Yamada, S.; Kaneko, M.K. The mouse–canine chimeric anti-dog podoplanin antibody P38B exerts antitumor activity in mouse xenograft models.
Biochem. Biophys. Rep. 2019, 17, 23–26, doi:10.1016/j.bbrep.2018.11.005.
Yoshitake, R.; Saeki, K.; Watanabe, M.; Nakaoka, N.; Ong, S.M.; Hanafusa, M.; Choisunirachon, N.; Fujita,N.; Nishimura, R.; Nakagawa, T. Molecular investigation of the direct anti-tumour effects of nonsteroidal
anti-inflammatory drugs in a panel of canine cancer cell lines. Vet. J. 2017, 221, 38–47,
doi:10.1016/j.tvjl.2017.02.001.
Uchida, M.; Saeki, K.; Maeda, S.; Tamahara, S.; Yonezawa, T.; Matsuki, N. Apoptosis inhibitor ofmacrophage (AIM) reduces cell number in canine histiocytic sarcoma cell lines. J. Vet. Med. Sci. 2016, 78,
1515–1520, doi:10.1292/jvms.16-0120.
Ohashi, E.; Hong, S.H.; Takahashi, T.; Nakagawa, T.; Mochizuki, M.; Nishimura, R.; Sasaki, N. Effect ofRetinoids on Growth Inhibition of Two Canine Melanoma Cell Lines. J. Vet. Med. Sci. 2001, 63, 83–86,
doi:10.1292/jvms.63.83.
Inoue, K.; Ohashi, E.; Kadosawa, T.; Hong, S.H.; Matsunaga, S.; Mochizuki, M.; Nishimura, R.; Sasaki, N.
Establishment and characterization of four canine melanoma cell lines. J. Vet. Med. Sci. 2004, 66, 1437–1440,
doi:10.1292/jvms.66.1437.
Fujii, Y.; Kaneko, M.; Neyazaki, M.; Nogi, T.; Kato, Y.; Takagi, J. PA tag: A versatile protein tagging systemusing a super high affinity antibody against a dodecapeptide derived from human podoplanin. Protein
Expr. Purif. 2014, 95, 240–247, doi:10.1016/j.pep.2014.01.009.
Reference, Q. Veterinary cooperative oncology group—Common terminology criteria for adverse events(VCOG-CTCAE) following chemotherapy or biological antineoplastic therapy in dogs and cats v1.1. Vet.
Comp. Oncol. 2016, 14, 417–446, doi:10.1111/vco.283.
Nguyen, S.M.; Thamm, D.H.; Vail, D.M.; London, C.A. Response evaluation criteria for solid tumours indogs (v1.0): A Veterinary Cooperative Oncology Group (VCOG) consensus document. Vet. Comp. Oncol.
2015, 13, 176–183, doi:10.1111/vco.12032.
Ogasawara, S.; Honma, R.; Kaneko, M.K.; Fujii, Y.; Kagawa, Y.; Konnai, S.; Kato, Y. Podoplanin Expression
in Canine Melanoma. Monoclon. Antib. Immunodiagn. Immunother. 2016, 35, 304–306,
doi:10.1089/mab.2016.0040.
Abe, S.; Morita, Y.; Kaneko, M.K.; Hanibuchi, M.; Tsujimoto, Y.; Goto, H.; Kakiuchi, S.; Aono, Y.; Huang, J.;
Sato, S.; et al. A Novel Targeting Therapy of Malignant Mesothelioma Using Anti-Podoplanin Antibody. J.
Immunol. 2013, 190, 6239–6249, doi:10.4049/jimmunol.1300448.
Kato, Y.; Kunita, A.; Abe, S.; Ogasawara, S.; Fujii, Y.; Oki, H.; Fukayama, M.; Nishioka, Y.; Kaneko, M.K.
The chimeric antibody chLpMab-7 targeting human podoplanin suppresses pulmonary metastasis via
ADCC and CDC rather than via its neutralizing activity. Oncotarget 2015, 6, 36003–36018,
doi:10.18632/oncotarget.5339.

Cells 2020, 9, 2529

48.

49.
50.
51.
52.

53.
54.
55.

56.

57.
58.

59.

60.

61.
62.
63.

64.
65.
66.

67.

18 of 19

Kaneko, M.K.; Abe, S.; Ogasawara, S.; Fujii, Y.; Yamada, S.; Murata, T.; Uchida, H.; Tahara, H.; Nishioka,
Y.; Kato, Y. Chimeric Anti-Human Podoplanin Antibody NZ-12 of Lambda Light Chain Exerts Higher
Antibody-Dependent Cellular Cytotoxicity and Complement-Dependent Cytotoxicity Compared with NZ8 of Kappa Light Chain. Monoclon. Antib. Immunodiagn. Immunother. 2017, 36, 25–29,
doi:10.1089/mab.2016.0047.
Chames, P.; Van Regenmortel, M.; Weiss, E.; Baty, D. Therapeutic antibodies: Successes, limitations andhopes for the future. Br. J. Pharmacol. 2009, 157, 220–233, doi:10.1111/j.1476-5381.2009.00190.x.
Guan, M.; Zhou, Y.P.; Sun, J.L.; Chen, S.C. Adverse Events of Monoclonal Antibodies Used for Cancer
Therapy. BioMed Res. Int. 2015, 2015, doi:10.1155/2015/428169.
Gharwan, H.; Groninger, H. Kinase inhibitors and monoclonal antibodies in oncology: Clinicalimplications. Nat. Rev. Clin. Oncol. 2016, 13, 209–227, doi:10.1038/nrclinonc.2015.213.
Roselló, S.; Blasco, I.; Garća Fabregat, L.; Cervantes, A.; Jordan, K. Management of infusion reactions tosystemic anticancer therapy: ESMO Clinical Practice Guidelines. Ann. Oncol. 2017, 28, iv100–iv118,
doi:10.1093/annonc/mdx216.
Brain, A.B. Adverse events to monoclonal antibodies used for cancer therapy. Focus on hypersensitivity
responses. Oncoimmunology 2013, 10, e26333, doi:10.4161/onci.26333.
Tarazona, R.; Duran, E.; Solana, R. Natural killer cell recognition of melanoma: New clues for a more
effective immunotherapy. Front. Immunol. 2016, 6, 649, doi:10.3389/fimmu.2015.00649.
Nishiya, A.T.; Massoco, C.O.; Felizzola, C.R.; Perlmann, E.; Batschinski, K.; Tedardi, M.V.; Garcia, J.S.;
Mendonça, P.P.; Teixeira, T.F.; Dagli, M.L.Z. Comparative aspects of canine melanoma. Vet. Sci. 2016, 3, 7,
doi:10.3390/vetsci3010007.
Hernandez, B.; Adissu, H.A.; Wei, B.R.; Michael, H.T.; Merlino, G.; Mark Simpson, R. Naturally occurring
canine melanoma as a predictive comparative oncology model for human mucosal and other triple wildtype melanomas. Int. J. Mol. Sci. 2018, 19, 394, doi:10.3390/ijms19020394.
Prouteau, A.; André, C. Canine melanomas as models for human melanomas: Clinical, histological, andgenetic comparison. Genes 2019, 10, 501, doi:10.3390/genes10070501.
Simpson, R.M.; Bastian, B.C.; Michael, H.T.; Webster, J.D.; Prasad, M.L.; Conway, C.M.; Prieto, V.M.; Gary,
J.M.; Goldschmidt, M.H.; Esplin, D.G.; et al. Sporadic naturally occurring melanoma in dogs as a preclinicalmodel for human melanoma. Pigment Cell Melanoma Res. 2014, 27, 37–47, doi:10.1111/pcmr.12185.
Goldenberg, M.M. Trastuzumab, a recombinant DNA-derived humanized monoclonal antibody, a novel
agent for the treatment of metastatic breast cancer. Clin. Ther. 1999, 21, 309–318, doi:10.1016/S01492918(00)88288-0.
Vogel, C.L.; Cobleigh, M.A.; Tripathy, D.; Gutheil, J.C.; Harris, L.N.; Fehrenbacher, L.; Slamon, D.J.;
Murphy, M.; Novotny, W.F.; Burchmore, M.; et al. Efficacy and safety of trastuzumab as a single agent infirst-line treatment of HER2-overexpressing metastatic breast cancer. J. Clin. Oncol. 2002, 20, 719–726,
doi:10.1200/JCO.20.3.719.
Smith, E. Efficacy and safety of Herceptin in women with metastatic breast cancer: Results from pivotal
clinical studies. Anticancer Drugs 2001, 12 (Suppl. 4), S3–S10, doi:10.1097/00001813-200112004-00002.
Sproston, N.R.; Ashworth, J.J. Role of C-reactive protein at sites of inflammation and infection. Front.
Immunol. 2018, 9, 754, doi:10.3389/fimmu.2018.00754.
Abolhassani, A.R.; Schuler, G.; Kirchberger, M.C.; Heinzerling, L. C-reactive protein as an early marker of
immune-related adverse events. J. Cancer Res. Clin. Oncol. 2019, 145, 2625–2631, doi:10.1007/s00432-01903002-1.
Le Guenno, G.; Ruivard, M.; Charra, L.; Philippe, P. Rituximab-induced serum sickness in refractory
immune thrombocytopenic purpura. Intern. Med. J. 2011, 41, 202–205, doi:10.1111/j.1445-5994.2010.02384.x.
Maker, J.H.; Stroup, C.M.; Huang, V.; James, S.F. Antibiotic Hypersensitivity Mechanisms. Pharmacy 2019,7, 122, doi:10.3390/pharmacy7030122.
Watanabe, M.; Sugimoto, Y.; Tsuruo, T. Expression of a Mr 41,000 Glycoprotein Associated with Thrombinindependent Platelet Aggregation in High Metastatic Variants of Murine B16 Melanoma. Cancer Res. 1990,
50, 6657–6662.
Manuscript, A.; Proximity, I. T-Cell and NK-Cell Infiltration into Solid Tumors: A Key Limiting Factor for
Efficacious
CancerImmunotherapy
Ignacio.
Cancer
Discov.
2011,4,
522–526,
doi:10.1126/scisignal.2001449.Engineering.

Cells 2020, 9, 2529

68.

69.

70.
71.

72.
73.

74.

75.

19 of 19

Ben-Shmuel, A.; Biber, G.; Barda-Saad, M. Unleashing Natural Killer Cells in the Tumor
Microenvironment—The Next Generation of Immunotherapy? Front. Immunol. 2020, 11, 275,
doi:10.3389/fimmu.2020.00275.
Horiuchi, Y.; Tominaga, M.; Ichikawa, M.; Yamashita, M.; Okano, K.; Jikumaru, Y.; Nariai, Y.; Nakajima,Y.; Kuwabara, M.; Yukawa, M. Relationship between regulatory and type 1 T cells in dogs with oralmalignant melanoma. Microbiol. Immunol. 2010, 54, 152–159, doi:10.1111/j.1348-0421.2009.00194.x.
Casi, G.; Neri, D. Antibody-drug conjugates: Basic concepts, examples and future perspectives. J. Control.
Release 2012, 161, 422–428, doi:10.1016/j.jconrel.2012.01.026.
Lewis Phillips, G.D.; Li, G.; Dugger, D.L.; Crocker, L.M.; Parsons, K.L.; Mai, E.; Blättler, W.A.; Lambert,
J.M.; Chari, R.V.J.; Lutz, R.J.; et al. Targeting HER2-positive breast cancer with trastuzumab-DM1, an
antibody-cytotoxic drug conjugate. Cancer Res. 2008, 68, 9280–9290, doi:10.1158/0008-5472.CAN-08-1776.
Sadelain, M.; Brentjens, R.; Riviere, I. The basic principles of chimeric antigen receptor (CAR) design.
October 2008, 141, 520–529, doi:10.1016/j.surg.2006.10.010.Use.
Kochenderfer, J.N.; Dudley, M.E.; Kassim, S.H.; Somerville, R.P.T.; Carpenter, R.O.; Maryalice, S.S.; Yang,
J.C.; Phan, G.Q.; Hughes, M.S.; Sherry, R.M.; et al. Chemotherapy-refractory diffuse large B-cell lymphoma
and indolent B-cell malignancies can be effectively treated with autologous T cells expressing an anti-CD19
chimeric antigen receptor. J. Clin. Oncol. 2015, 33, 540–549, doi:10.1200/JCO.2014.56.2025.
Maude, S.L.; Frey, N.; Shaw, P.A.; Aplenc, R.; Barrett, D.M.; Bunin, N.J.; Chew, A.; Gonzalez, V.E.; Zheng,Z.; Lacey, S.M.; et al. Chimeric antigen receptor T cells for sustained remissions in leukemia. N. Engl. J. Med.
2014, 371, 1507–1517, doi:10.1056/NEJMoa1407222.
Shiina, S.; Ohno, M.; Ohka, F.; Kuramitsu, S.; Yamamichi, A.; Kato, A.; Motomura, K.; Tanahashi, K.;
Yamamoto, T.; Watanabe, R.; et al. CAR T cells targeting Podoplanin reduce orthotopic glioblastomas inmouse brains. Cancer Immunol. Res. 2016, 4, 259–268, doi:10.1158/2326-6066.CIR-15-0060.

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