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Tumor-associated glycolipids such as NeuGc GM3 are auspicious molecular targets in antineoplastic therapies and vaccine strategies. 14F7 is a monoclonal IgG1 with high clinical potential in cancer immunotherapy as it displays extraordinary specificity for NeuGc GM3, while it does not recognize the very similar, ubiquitous NeuAc GM3. Here we present the 2.3 Å crystal structure of the 14F7 antigen-binding domain (14F7 scFv) in complex with the NeuGc GM3 trisaccharide. Modeling analysis and previous mutagenesis data suggest that 14F7 may also bind to an alternative NeuGc GM3 conformation, not observed in the crystal structure. The most intriguing finding, however, was that a water molecule centrally placed in the complementarity-determining region directly mediates the specificity of 14F7 to NeuGc GM3. This has profound impact on the complexity of engineering in the binding site and provides an excellent example of the importance in understanding the water structure in antibody-antigen interactions., (© The Author(s) 2021. Published by Oxford University Press.)

Background: Daratumumab (DARA) is a monoclonal antibody for treatment of plasma cell myeloma targeting CD38, a surface molecule expressed on plasma cells and red blood cells (RBCs). This complicates blood bank testing, requiring dithiothreitol (DTT) to remove DARA interference. A simple in-house method of removing DARA interference without use of DTT, a potentially hazardous chemical, is desirable. We demonstrate a trypsin-based method to remove interference in antibody testing at a medical center (MC), with parallel testing at an immunohematology reference laboratory (IRL)., Study Design and Methods: Pre-DARA type and screen (T&S) samples were obtained from 61 patients for antibody testing and RBC phenotyping using untreated reagent RBCs. Subsequent post-DARA T&S testing was performed with untreated reagent RBCs to demonstrate interference and repeated after trypsin treatment. Positive trypsin-treated antibody screens were reflexed to antibody identification using trypsin-treated panel cells. Parallel testing was performed on the same post-DARA samples at IRL., Results: DARA interference was detected in 61/61 (100%) samples by MC and IRL. After trypsin treatment, DARA interference was eliminated in 60/61 (98.4%) antibody screens by both institutions with an overall percent agreement of 96.7% (95% confidence interval [CI] 88.7%-99.6%). Identification of known alloantibodies was confirmed in 3/3 patients with 100% concordant results between MC and IRL. There were no false-negative results demonstrated by IRL's functionally CD38-negative controls., Conclusion: Our in-house trypsin-based method enables pretransfusion testing of patients receiving DARA in an accurate and cost-effective manner without missing clinically significant alloantibodies. This presents an additional testing option where DTT use is undesirable., (© 2021 AABB.)

Early success with brentuximab vedotin in treating classical Hodgkin lymphoma spurred an influx of at least 20 monomethyl auristatin E (MMAE) antibody-drug conjugates (ADCs) into clinical trials. While three MMAE-ADCs have been approved, most of these conjugates are no longer being investigated in clinical trials. Some auristatin conjugates show limited or no efficacy at tolerated doses, but even for drugs driving initial remissions, tumor regrowth and metastasis often rapidly occur. Here we describe the development of second-generation therapeutic ADCs targeting Lymphocyte antigen 6E (Ly6E) where the tubulin polymerization inhibitor MMAE (Compound 1 ) is replaced with DNA-damaging agents intended to drive increased durability of response. Comparison of a seco -cyclopropyl benzoindol-4-one (CBI)-dimer (compound 2 ) to MMAE showed increased potency, activity across more cell lines, and resistance to efflux by P -glycoprotein, a drug transporter commonly upregulated in tumors. Both anti-Ly6E-CBI and -MMAE conjugates drove single-dose efficacy in xenograft and patient-derived xenograft models, but seco- CBI-dimer conjugates showed reduced tumor outgrowth following multiple weeks of treatment, suggesting that they are less susceptible to developing resistance. In parallel, we explored approaches to optimize the targeting antibody. In contrast to immunization with recombinant Ly6E or Ly6E DNA, immunization with virus-like particles generated a high-affinity anti-Ly6E antibody. Conjugates to this antibody improve efficacy versus a previous clinical candidate both in vitro and in vivo with multiple cytotoxics. Conjugation of compound 2 to the second-generation antibody results in a substantially improved ADC with promising preclinical efficacy.

PD-1/PD-L1 pathway plays a role in inhibiting immune response. Therapeutic antibodies aimed at blocking the PD-1/PD-L1 interaction have entered clinical development and have been approved for a variety of cancers. However, the clinical benefits are reduced to a group of patients. The research in combined therapies, which allow for a greater response, is strongly encouraging. We previously characterized a polyphenol-rich extract from Caesalpinia spinosa (P2Et) with antitumor activity in both melanoma and breast carcinoma, as well as immunomodulatory activity. We hypothesize that the combined treatment with P2Et and anti-PD-L1 can improve the antitumor response through an additive antitumor effect. We investigated the antitumor and immunomodulatory activity of P2Et and anti-PD-L1 combined therapy in B16-F10 melanoma and 4T1 breast carcinoma. We analyzed tumor growth, hematologic parameters, T cell counts, cytokine expression, and T cell cytotoxicity. In the melanoma model, combined P2Et and anti-PD-L1 therapy has the following effects: decrease in tumor size; increase in the number of activated CD4 + and CD8 + T cells; decrease in the number of suppressor myeloid cells; increase in PD-L1 expression; decrease in the frequency of CD8 + T cell expressing PD-1; improvement in the cytotoxic activity of T cells; and increase in the IFN γ secretion. In the breast cancer model, P2Et and PD-L1 alone or in combination show antitumor effect with no clear additive effect. This study shows that combined therapy of P2Et and anti-PD-L1 can improve antitumor response in a melanoma model by activating the immune response and neutralizing immunosuppressive mechanisms., (Copyright © 2020 Lasso, Gomez-Cadena, Urueña, Donda, Martinez-Usatorre, Romero, Barreto and Fiorentino.)

Antibody-drug conjugates (ADCs) are novel drugs that exploit the specificity of a monoclonal antibody (mAb) to reach target antigens expressed on cancer cells for the delivery of a potent cytotoxic payload. ADCs provide a unique opportunity to deliver drugs to tumor cells while minimizing toxicity to normal tissue, achieving wider therapeutic windows and enhanced pharmacokinetic/pharmacodynamic properties. To date, nine ADCs have been approved by the FDA and more than 80 ADCs are under clinical development worldwide. In this paper, we provide an overview of the biology and chemistry of each component of ADC design. We briefly discuss the clinical experience with approved ADCs and the various pathways involved in ADC resistance. We conclude with perspectives about the future development of the next generations of ADCs, including the role of molecular imaging in drug development.

Supraphysiological levels of IL-7 induce increase counts of pre-B cells, naive T cells and memory phenotype CD8 + T cells. Immunocomplexes of IL-7 and αIL-7 mAb M25 (IL-7/M25) were described as IL-7 superagonist in vivo. Thus, treatment of mice with IL-7/M25 remarkably increases the size of the T cell pool. We decided to use IL-7/M25 in order to expand the T cell population prior to the administration of αCTLA-4 and αPD-1 mAbs in tumor-bearing mice and in turn boost the immunotherapy based on a combination of CTLA-4 and PD-1 blockage. We found that just four doses of IL-7/M25 increased the absolute numbers of splenocytes approximately fivefold and significantly shifted the CD4 + :CD8 + T cell ratio in favor of CD8 + T cells. There was also a substantive increase in relative counts of memory phenotype CD8 + T cells (approximately threefold) within CD8 + T cells but a significant decrease (approximately 30%) in relative counts of Treg cells within CD4 + T cells. All these data suggest that IL-7/M25 offer a suitable approach to potentiate tumor immunotherapy through CTLA-4 and PD-1 blockage. Unexpectedly, IL-7/M25 significantly abrogated the antitumor activity of αCTLA-4 plus αPD-1 mAbs in the following mouse tumor models: MC-38 and CT26 colon carcinoma and B16F10 melanoma. This paradoxical effect of IL-7/M25 on the antitumor activity of CTLA-4 and PD-1 blockage was not mediated via either increased levels of IL-10 or TGF-β in the sera or increased counts of IL-10-producing B or T cells in the spleen of mice injected with IL-7/M25. Thus, our work shows that caution should be exercised when combining two immunotherapy approaches together., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Locally advanced or metastatic urothelial cancer is an aggressive form of cancer with high recurrence rates and low survival. Nectin-4 is a cell adhesion molecule commonly expressed in several tumors, including high expression in urothelial cancer. Enfortumab vedotin is an antibody-drug conjugate composed of an anti-Nectin-4 humanized monoclonal antibody linked to the microtubule disrupting agent, monomethyl auristatin E. In this phase I study (NCT03070990), Japanese patients with locally advanced/metastatic urothelial cancer treated with prior chemotherapy, or ineligible for cisplatin, were randomized 1:1 to receive 1.0 mg/kg (Arm A) or 1.25 mg/kg (Arm B) enfortumab vedotin on Days 1, 8, and 15 of each 28-day cycle. Assessing the pharmacokinetic and safety/tolerability profiles of enfortumab vedotin were primary objectives; investigator-assessed antitumor activity (RECIST v1.1) was a secondary objective. Seventeen patients (n = 9, Arm A; n = 8, Arm B) received treatment. Pharmacokinetic data suggest a dose-dependent increase in enfortumab vedotin maximum concentration and area under the concentration-time curve at Day 7. Enfortumab vedotin was well tolerated across both doses. Dysgeusia and alopecia (n = 9 each) were the most common treatment-related adverse events. Regardless of attribution, grade ≥ 3 adverse events occurring in ≥2 patients were anemia and hypertension (n = 2 each). One patient achieved a confirmed complete response (Arm A) and five achieved confirmed partial responses (n = 3, Arm A; n = 2, Arm B). Objective response and disease control rates were 35.3% and 76.5%, respectively. In Japanese patients with locally advanced/metastatic urothelial cancer, enfortumab vedotin is well tolerated with preliminary antitumor activity and a pharmacokinetic profile consistent with prior reports.

In recent years, antibody-drug conjugates (ADCs) have become promising antitumor agents to be used as one of the tools in personalized cancer medicine. ADCs are comprised of a drug with cytotoxic activity cross-linked to a monoclonal antibody, targeting antigens expressed at higher levels on tumor cells than on normal cells. By providing a selective targeting mechanism for cytotoxic drugs, ADCs improve the therapeutic index in clinical practice. In this review, the chemistry of ADC linker conjugation together with strategies adopted to improve antibody tolerability (by reducing antigenicity) are examined, with particular attention to ADCs approved by the regulatory agencies (the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA)) for treating cancer patients. Recent developments in engineering Immunoglobulin (Ig) genes and antibody humanization have greatly reduced some of the problems of the first generation of ADCs, beset by problems, such as random coupling of the payload and immunogenicity of the antibody. ADC development and clinical use is a fast, evolving area, and will likely prove an important modality for the treatment of cancer in the near future.

Chimeric molecules which effect intracellular degradation of target proteins via E3 ligase-mediated ubiquitination (e.g., PROTACs) are currently of high interest in medicinal chemistry. However, these entities are relatively large compounds that often possess molecular characteristics which may compromise oral bioavailability, solubility, and/or in vivo pharmacokinetic properties. Accordingly, we explored whether conjugation of chimeric degraders to monoclonal antibodies using technologies originally developed for cytotoxic payloads might provide alternate delivery options for these novel agents. In this report we describe the construction of several degrader-antibody conjugates comprised of two distinct ERα-targeting degrader entities and three independent ADC linker modalities. We subsequently demonstrate the antigen-dependent delivery to MCF7-neo/HER2 cells of the degrader payloads that are incorporated into these conjugates. We also provide evidence for efficient intracellular degrader release from one of the employed linkers. In addition, preliminary data are described which suggest that reasonably favorable in vivo stability properties are associated with the linkers utilized to construct the degrader conjugates., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Human epidermal growth factor receptor 2 (HER2) is an attractive target for cancer therapy, although a large fraction of tumors that express HER2 may still resist first-line therapies. Immunotoxins with antibodies that are armed with extremely potent cytotoxic toxin molecules may provide an important solution to this problem. In this work, we constructed three new anti-HER2 immunotoxins by using single-domain antibody (sdAb) molecules as the targeting moiety and the improved toxin PE24X7 as the effector with the aim of simplifying the preparation and reducing the off-target toxicity of the immunotoxins. Due to the beneficial outcomes of sdAb molecules, the synthesized immunotoxins were efficiently expressed in soluble form, avoiding the refolding process required by the common immunotoxin design and having high solubility and stability. Cell toxicity experiments showed that they have high cytotoxicity against various HER2-positive tumor cells and good selectivity (more than 1000-fold) towards HER2-positive rather than HER2-negative cells. Importantly, in vivo treatment experiments showed that one of the new immunotoxins could efficiently halt tumor growth at doses lower than 0.75 mg/kg, and it had a maximum tolerated dose (MTD) higher than 8.0 mg/kg, showing a substantially improved MTD and a broadened therapeutic window than the previously reported anti-HER2 immunotoxins. Given that PE toxin-based immunotoxins have been approved for clinical cancer therapy, the unique characteristics of the immunotoxins presented here make them promising for use in the development of anti-HER2 cancer therapeutics., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Mesothelin (MSLN) is a cell surface glycoprotein overexpressed in several solid malignancies, including gastric, lung, mesothelioma, pancreatic and ovarian cancers. While several MSLN-targeting therapeutic approaches are in development, only limited efficacy has been achieved in patients. A potential shortcoming of several described antibody-based approaches is that they target the membrane distal region of MSLN and, additionally, are known to be handicapped by the high levels of circulating soluble MSLN in patients. We show here, using monoclonal antibodies (mAbs) targeting different MSLN-spanning epitopes, that the membrane-proximal region resulted in more efficient killing of MSLN-positive tumor cells in antibody-dependent cell-mediated cytotoxicity (ADCC) assays. Surprisingly, no augmented killing was observed in antibody-dependent cellular phagocytosis (ADCP) by mAbs targeting this membrane-proximal region. To further increase the ADCP potential, we, therefore, generated bispecific antibodies (bsAbs) coupling a high-affinity MSLN binding arm to a blocking CD47 arm. Here, targeting the membrane-proximal domain of MSLN demonstrated enhanced ADCP activity compared to membrane-distal domains when the bsAbs were used in in vitro phagocytosis killing assays. Importantly, the superior anti-tumor activity was also translated in xenograft tumor models. Furthermore, we show that the bsAb approach targeting the membrane-proximal epitope of MSLN optimized ADCC activity by augmenting FcγR-IIIA activation and enhanced ADCP via a more efficient blockade of the CD47/SIRPα axis.

The importance of monoclonal antibodies in oncology has increased drastically following the discovery of Milstein and Kohler. Since the first approval of the monoclonal antibody, i.e. Rituximab in 1997 by the FDA, there was a decline in further applications but this number has significantly increased over the last three decades for various therapeutic applications due to the lesser side effects in comparison to the traditional chemotherapy methods. Presently, numerous monoclonal antibodies have been approved and many are in queue for approval as a strong therapeutic agent for treating hematologic malignancies and solid tumors. The main target checkpoints for the monoclonal antibodies against cancer cells include EGFR, VEGF, CD and tyrosine kinase which are overexpressed in malignant cells. Other immune checkpoints like CTLA-4, PD-1 and PD-1 receptors targeted by the recently developed antibodies increase the capability of the immune system in destroying the cancerous cells. Here, in this review, the mechanism of action, uses and target points of the approved mAbs against cancer have been summarized., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Antibody-drug conjugates (ADCs), which consist of three components, antibody, linker, and payload, can function as "magic bullets". These conjugates offer the ability to target drug delivery to specific cells, based on cell-specific recognition and the binding of an antigen by a monoclonal antibody (mAb). In particular, by delivering a cytotoxic payload to cancer cells, ADCs are expected to provide a breakthrough in oncology treatments by providing a way to increase efficacy and decrease toxicity, in comparison with traditional chemotherapeutic treatments. The development of ADC therapeutics has dramatically progressed in the past decade and two ADCs have been approved and used as anticancer drugs in the clinic. However, several critical issues regarding the performance of ADCs are still being discussed and investigated. Indeed, in the past few years, several groups have reported that, changing the number and position of the drug payloads in the ADCs, affects the pharmacokinetics, drug release rates, and biological activity. The use of conventional heterogeneous conjugation methods for ADC preparation results in the drug/antibody ratio and connecting position of the payload having stochastic distributions. Therefore, it is important to investigate how these potential problems can be circumvented through site-specific conjugation. Herein, various site-specific chemical conjugation strategies with native mAbs that are currently used for the production of ADCs, including residue-selective labeling for generating ADCs, disulfide rebridging, and affinity-peptide-mediated site-specific chemical conjugation technologies, are reviewed and described., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background and Purpose: Polatuzumab vedotin is an antibody-drug conjugate (ADC) being developed for non-Hodgkin's lymphoma. It contains a humanized anti-CD79b IgG1 monoclonal antibody linked to monomethyl auristatin E (MMAE), an anti-mitotic agent. Polatuzumab vedotin binds to human CD79b only. Therefore, a surrogate ADC that binds to cynomolgus monkey CD79b was used to determine CD79b-mediated pharmacological effects in the monkey and to enable first-in-human clinical trials., Experimental Approach: Polatuzumab vedotin, the surrogate ADC, and the corresponding antibodies were evaluated in different assays in vitro and in animals. In vitro assessments included binding to peripheral blood mononuclear cells from different species, binding to a human and monkey CD79b-expressing cell line, binding to human Fcγ receptors, and stability in plasma across species. In vivo, ADCs were assessed for anti-tumour activity in mice, pharmacokinetics/pharmacodynamics in monkeys, and toxicity in rats and monkeys., Key Results: Polatuzumab vedotin and surrogate ADC bind with similar affinity to human and cynomolgus monkey B cells, respectively. Comparable in vitro plasma stability, in vivo anti-tumour activity, and mouse pharmacokinetics were also observed between the surrogate ADC and polatuzumab vedotin. In monkeys, only the surrogate ADC showed B-cell depletion and B-cell-mediated drug disposition, but both ADCs showed similar MMAE-driven myelotoxicity, as expected., Conclusions and Implications: The suitability of the surrogate ADC for evaluation of CD79b-dependent pharmacology was demonstrated, and anti-tumour activity, pharmacokinetics/pharmacodynamics, and toxicity data with both ADCs supported the entry of polatuzumab vedotin into clinical trials., (© 2019 Genentech Inc. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Purpose This Phase I trial evaluated the maximum tolerated dose, safety, pharmacokinetics, pharmacodynamics and preliminary efficacy of tarextumab (OMP-5948), a novel cross-reactive antibody which binds and selectively inhibits signaling via both Notch2 and Notch3, in adult patients with advanced malignancies. Methods Standard 3 + 3 design with tarextumab 0.5, 1, 2.5, or 5 mg/kg weekly, or 5, 7.5, or 10 mg/kg every other week, or 7.5 mg every 3 weeks. Dose-limiting toxicities (DLT) were assessed during the first 28 days. Results Forty-two patients received tarextumab (21 weekly, 15 every other week, 6 every three weeks). 2/6 subjects at the 5 mg/kg weekly dose, 2/3 at 10 mg/kg every other week, and 0/6 at 7.5 mg/kg every three weeks had a DLT. The maximum tolerated dose (MTD) was 2.5 mg/kg weekly, and 7.5 mg/kg on the every other and every three week schedules. Gastrointestinal (GI) toxicity was the most common adverse event with diarrhea (81%), fatigue (48%), nausea (45%), anorexia (38%), and vomiting (38%) and abdominal pain and constipation (24% each). Biomarker analysis showed regulation of stem cell and Notch gene signaling. Conclusion Tarextumab was generally well-tolerated at doses <2.5 mg weekly and 7.5 mg/kg every other and every third week. Diarrhea was dose-limiting above these levels, but relatively easily managed at lower doses. Inhibition of Notch pathway signaling was demonstrated at these doses. ClinicalTrials.gov Identifier: NCT01277146.

Purpose Navicixizumab (OMP-305B83) is a bispecific antibody that inhibits delta-like ligand 4 and vascular endothelial growth factor. This Phase 1a trial assessed escalating doses of navicixizumab in refractory solid tumors patients. Design A 3 + 3 dose escalation design was used followed by the treatment of additional patients in an expansion cohort. Study objectives were determination of the maximum tolerated dose, safety, pharmacokinetics, pharmacodynamics, immunogenicity and efficacy. Results Sixty-six patients were treated once every 3 weeks in 8 dose-escalation cohorts (0.5, 1, 2.5, 3.5, 5, 7.5, 10, and 12.5 mg/kg) and an expansion cohort (7.5 mg/kg). The median age was 60 years and 68% of the patients were female. The most commonly enrolled tumor types were ovarian (12), colorectal (11) and breast, pancreatic, uterine and endometrial (4 each) cancers. As only 1 dose limiting toxicity occurred, the maximum tolerated dose was not reached, but 7.5 mg/kg was chosen as the dose for the expansion cohort. The treatment related adverse events (≥15% of patients) were hypertension (57.6%), headache (28.8%), fatigue (25.8%), and pulmonary hypertension (18.2%). Pulmonary hypertension was mostly asymptomatic at doses ≤5 mg/kg (6 Gr1, 1 Gr2), but was more severe at higher doses (4 Gr2, 1 Gr3). Navicixizumab's half-life was 11.4 days and there was a moderate (29%) incidence of anti-drug antibody formation. Four patients (3 ovarian cancer, 1 uterine carcinosarcoma) had a partial response and 17 patients had stable disease. Nineteen patients had a reduction in the size of their target lesions including 7/11 patients with ovarian cancer. Four patients remained on study for >300 days and 2 of these patients were on study for >500 days. Conclusions Navicixizumab can be safely administered with manageable toxicities and these data showed preliminary signs of antitumor activity in multiple tumor types, but was most promising in ovarian cancer. As a result these data justify its continued development in combination Phase 1b clinical trials.

Neuroblastoma (NB) is a common and deadly malignancy mostly observed in children. Evolution of therapeutic options for NB led to the addition of immunotherapeutic modalities to the previously recruited chemotherapeutic options. Molecular studies of the NB cells resulted in the discovery of many tumor-associated genes and antigens such as MYCN gene and GD2. MYCN  gene and GD2 surface antigen are two of the most practical discoveries regarding immunotherapy of neuroblastoma. The GD2 antigen has been targeted in many animal and human studies including Phase III clinical trials. Even though these antigens have changed the face of pediatric neuroblastoma, they do not take as much credit in immunotherapy of adult-onset neuroblastoma. Monoclonal antibodies have been designed to detect this antigen on the surface of NB tumor cells. Despite bettering the outcomes for NB patients, current therapies still fail in many cases. Studies are underway to discover more specific tumor-associated antigens and more effective treatment options. In the current narrative, immunotherapy of NB - from emerging of this therapeutic backbone in NB to the latest discoveries regarding this malignancy - has been reviewed.

The remarkable clinical success of immune-checkpoint inhibitors for the treatment of a growing number of cancer types has sparked interest in the discovery of novel forms of immunotherapy, which may be used alone or in combination. In this context, cytokine-based therapeutics are well poised to play a role in modern cancer therapy. This article focuses on antibody-cytokine fusion proteins (also called "immunocytokines") as one class of biopharmaceuticals that can substantially improve the therapeutic index and, thus, the applicability of cytokine products. In many preclinical settings, antibodies can be used to preferentially deliver many (but not all) types of cytokines to primary and metastatic tumor lesions. The antibody-based delivery of certain proinflammatory payloads (such as IL2, IL12, and TNF) to the tumor microenvironment can lead to a dramatic potentiation of their anticancer activity. However, although some fusion proteins have advanced to late-stage clinical trials, much work remains to be done in order to fully characterize the mechanism of action and the pharmaceutical potential of immunocytokines in the clinical setting. Various factors contribute to in vivo performance, including the target antigen, the antibody properties, the nature of the payload, the format of the fusion protein, the dose, and schedule, as well as their use in combination with other therapeutic modalities. Protein engineering opportunities and insights in cancer immunology are contributing to the development of next-generation immunocytokine products and of novel therapeutic concepts, with the goal to increase antitumor activity and reduce systemic toxicity (a common problem for cytokine-based biopharmaceuticals)., (©2019 American Association for Cancer Research.)

Glioblastoma is the most common malignant brain tumor. Efficient delivery of drugs targeting glioblastomas remains a challenge. Ephrin type-A receptor 3 (EPHA3) tyrosine kinase antibody-modified polylactide-co-glycolide (PLGA) nanoparticles (NPs) were developed to target glioblastoma via nose-to-brain delivery. Anti-EPHA3-modified, TBE-loaded NPs were prepared using an emulsion-solvent evaporation method, showed a sustained in vitro release profile up to 48 h and a mean particle size of 145.9 ± 8.7 nm. The cellular uptake of anti-EPHA3-modified NPs by C6 cells was significantly enhanced compared to that of nontargeting NPs (p < .01). In vivo imaging and distribution studies on the glioma-bearing rats showed that anti-EPHA3-modified NPs exhibited high fluorescence intensity in the brain and effectively accumulated to glioma tissues, indicating the targeting effect of anti-EPHA3. Glioma-bearing rats treated with anti-EPHA3-modified NPs resulted in significantly higher tumor cell apoptosis (p < .01) than that observed with other formulations and prolonged the median survival time of glioma-bearing rats to 26 days, which was 1.37-fold longer than that of PLGA NPs. The above results indicated that anti-EPHA3-modified NPs may potentially serve as a nose-to-brain drug carrier for the treatment of glioblastoma.

Although initially responsive to androgen signaling inhibitors (ASIs), metastatic castration-resistant prostate cancer (mCRPC) inevitably develops and is incurable. In addition to adenocarcinoma (adeno), neuroendocrine prostate cancer (NEPC) emerges to confer ASI resistance. We have previously combined laser capture microdissection and phage antibody display library selection on human cancer specimens and identified novel internalizing antibodies binding to tumor cells residing in their tissue microenvironment. We identified the target antigen for one of these antibodies as CD46, a multifunctional protein that is best known for negatively regulating the innate immune system. CD46 is overexpressed in primary tumor tissue and CRPC (localized and metastatic; adeno and NEPC), but expressed at low levels on normal tissues except for placental trophoblasts and prostate epithelium. Abiraterone- and enzalutamide-treated mCRPC cells upregulate cell surface CD46 expression. Genomic analysis showed that the CD46 gene is gained in 45% abiraterone-resistant mCRPC patients. We conjugated a tubulin inhibitor to our macropinocytosing anti-CD46 antibody and showed that the resulting antibody-drug conjugate (ADC) potently and selectively kills both adeno and NEPC cell lines in vitro (sub-nM EC50) but not normal cells. CD46 ADC regressed and eliminated an mCRPC cell line xenograft in vivo in both subcutaneous and intrafemoral models. Exploratory toxicology studies of the CD46 ADC in non-human primates demonstrated an acceptable safety profile. Thus, CD46 is an excellent target for antibody-based therapy development, which has potential to be applicable to both adenocarcinoma and neuroendocrine types of mCRPC that are resistant to current treatment.

Over the recent decades, the use of antibody-drug conjugates (ADCs) has led to a paradigm shift in cancer chemotherapy. Antibody-based treatment of various human tumors has presented dramatic efficacy and is now one of the most promising strategies used for targeted therapy of patients with a variety of malignancies, including hematological cancers and solid tumors. Monoclonal antibodies (mAbs) are able to selectively deliver cytotoxic drugs to tumor cells, which express specific antigens on their surface, and has been suggested as a novel category of agents for use in the development of anticancer targeted therapies. In contrast to conventional treatments that cause damage to healthy tissues, ADCs use mAbs to specifically attach to antigens on the surface of target cells and deliver their cytotoxic payloads. The therapeutic success of future ADCs depends on closely choosing the target antigen, increasing the potency of the cytotoxic cargo, improving the properties of the linker, and reducing drug resistance. If appropriate solutions are presented to address these issues, ADCs will play a more important role in the development of targeted therapeutics against cancer in the next years. We review the design of ADCs, and focus on how ADCs can be exploited to overcome multiple drug resistance (MDR)., (© 2018 Wiley Periodicals, Inc.)

Fibroblast growth factor receptor 1 (FGFR1) is a plasma membrane protein that transmits signals from the extracellular environment, regulating cell homeostasis and function. Dysregulation of FGFR1 leads to the development of human cancers and noncancerous diseases. Numerous tumors overproduce FGFR1, making this receptor a perspective target for cancer therapies. Antibody-drug conjugates (ADCs) are highly potent and selective anticancer agents. ADCs are composed of antibodies (targeting factors) fused to highly cytotoxic drugs (warheads). The efficiency of ADC strategy largely depends on the internalization of cytotoxic conjugate into cancer cells. Here, we have studied an interplay between affinity of anti-FGFR1 antibodies and efficiency of their cellular uptake. We have developed a unique set of engineered anti-FGFR1 antibodies that bind the same epitope in the extracellular part of FGFR1, but with different affinities. We have demonstrated that these antibodies are effectively taken up by cancer cells in the FGFR1-dependent manner. Interestingly, we have found that efficiency, defined as rate and level of antibody internalization, largely depends on the affinity of engineered antibodies towards FGFR1, as high affinity antibody displays fastest internalization kinetics. Our data may facilitate design of therapeutically relevant targeting molecules for selective treatment of FGFR1 overproducing cancers.

Purpose of Review: The unleashing of the immune system in an effort to fight cancer has proven to be an incredible advance in the war on cancer. However that breakthrough has come with a price in the form of serious and potentially fatal immune-related adverse events (irAEs)., Recent Findings: Rapid recognition and early intervention is imperative to avoid significant morbidity and mortality. Additionally, providers need to be aware that there are still new, rare, and long-term emerging irAEs that were not previously reported in clinical trials. Because of the significant difference between irAEs and those caused by chemotherapy and/or targeted therapy, providers must have a thorough understanding of which events would be considered immune related and require treatment. This review will cover descriptions of the most common and uncommon but serious irAEs experienced by patients on immunotherapy, as well as management of these irAEs.

Background: Mucin1 (MUC1) is a highly glycosylated transmembrane protein that has gained attention because of its overexpression in various cancers. However, MUC1-targeted therapeutic antibodies have not yet been approved for cancer therapy. MUC1 is cleaved to two subunits, MUC1-N and MCU1-C. MUC1-N is released from the cell surface, making MUC1-C a more reasonable target for cancer therapy. Therefore, we produced a monoclonal antibody (anti-hMUC1) specific to the extracellular region of MUC1-C and evaluated its effects in vitro and in vivo . Methods : We produced a monoclonal antibody (anti-hMUC1) using a purified recombinant human MUC1 polypeptide and our novel immunization protocol. The reactivity of anti-hMUC1 was characterized by ELISA, western blotting and immunoprecipitation analyses. The localization of the antibody in the breast cancer cells after binding was determined by confocal image analysis. The effects of the antibody on the growth of cells were also investigated. We injected anti-hMUC1 and performed in vivo tracing analysis in xenograft mouse models. In addition, expression of MUC1 in tissue sections from patients with breast cancer was assessed by immunohistochemistry with anti-hMUC1. Results : The anti-hMUC1 antibody recognized recombinant MUC1 as well as native MUC1-C protein in breast cancer cells. Anti-hMUC1 binds to the membrane surface of cells that express MUC1 and is internalized in some cancer cell lines. Treatment with anti-hMUC1 significantly reduced proliferation of cells in which anti-hMUC1 antibody is internalized. Furthermore, the anti-hMUC1 antibody was specifically localized in the MUC1-expressing breast cancer cell-derived tumors in xenograft mouse models. Based on immunohistochemistry analysis, we detected significantly higher expression of MUC1 in cancer tissues than in normal control tissues. Conclusion : Our results reveal that the anti-hMUC1 antibody targets the extracellular region of MUC1-C subunit and may have utility in future applications as an anti-breast cancer agent., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Immunotherapy has recently catapulted to the forefront of treatments for patients with solid tumors. Given its inherent immunogenic properties, renal cell carcinoma (RCC) has historically responded to immunotherapy and remains primed for further development. Although immunotherapy with high-dose interleukin 2 was a primary treatment for advanced RCC (aRCC), recent discoveries of key molecular and immunological alterations have led to the FDA-approval of nivolumab, an antiprogrammed cell death inhibitor, which has demonstrated an overall survival in patients with previously treated aRCC. However, despite recent therapeutic advances, aRCC remains an incurable disease for most patients. In this review, we assess the current landscape and future developments of immunotherapy in aRCC., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The proto-oncogene tyrosine kinase ROS1 plays a key role in carcinogenesis through gene rearrangement to form a fusion protein with other genes, in which the C-terminal intracellular region of ROS1 participates. The possibility of wild type ROS1 overexpression through epigenetic regulation has been proposed. Here, we generated an antibody, 3B20, reactive to the N-terminal region of ROS1 to use it for the detection of wild type ROS1 in cancerous tissues. Using immunoblot and immunoprecipitation analyses, we found that 3B20 also reacted with heat shock proteins (Hsp)70s. Using homology searching, ROS1 and Hsp70s were found to share an identical amino acid sequence: DLGT. Using alanine mutagenesis of ROS1, the epitope was found to harbor this sequence. To modify the idiotope with the aim of selecting more specific antibodies, we introduced random mutations into the heavy chain complementarity-determining region 3 and successfully generated an antibody clone, 3B20-G1K, with a point mutation that only reacted with ROS1 in enzyme-linked immunosorbent assays, and in immunoblot and immunoprecipitation analysis. In immunohistochemical analysis using 3B20-G1K, ROS1 was found to be absent in normal lung tissues and was overexpressed in a case of lung adenocarcinoma., (Copyright © 2017 Elsevier Inc. All rights reserved.)

MP0250 is a multi-domain drug candidate currently being tested in clinical trials for the treatment of cancer. It comprises one anti-vascular endothelial growth factor-A (VEGF-A), one anti-hepatocyte growth factor (HGF), and two anti-human serum albumin (HSA) DARPin® domains within a single polypeptide chain. While there is first clinical validation of a single-domain DARPin® drug candidate, little is known about DARPin® drug candidates comprising multiple domains. Here, we show that MP0250 can be expressed at 15 g/L in soluble form in E. coli high cell-density fermentation, it is stable in soluble/frozen formulation for 2 years as assessed by reverse phase HPLC, it has picomolar potency in inhibiting VEGF-A and HGF in ELISA and cellular assays, and its domains are simultaneously active as shown by surface plasmon resonance. The inclusion of HSA-binding DARPin® domains leads to a favorable pharmacokinetic profile in mouse and cynomolgus monkey, with terminal half-lives of ∼ 30 hours in mouse and ∼ 5 days in cynomolgus monkey. MP0250 is thus a highly potent drug candidate that could be particularly useful in oncology. Beyond MP0250, the properties of MP0250 indicate that multi-domain DARPin® proteins can be valuable next-generation drug candidates.

Hepatocyte growth factor receptor (HGFR, c-Met) is an essential member of the receptor tyrosine kinase (RTK) family that is often dysregulated during tumor progression, driving a malignant phenotypic state and modulating important cellular functions including tumor growth, invasion, metastasis, and angiogenesis, providing a strong rationale for targeting HGF/c-Met signaling axis in cancer therapy. Based on its protumorigenic potentials, we developed IRCR201, a potent antagonistic antibody targeting the plexin-semaphorin-integrin (PSI) domain of c-Met, using synthetic human antibody phage libraries. We characterized and evaluated the biochemical properties and tumor inhibitory effect of IRCR201 in vitro and in vivo. IRCR201 is a novel fully-human bivalent therapeutic antibody that exhibits cross-reactivity against both human and mouse c-Met proteins with high affinity and specificity. IRCR201 displayed low agonist activity and rapidly depleted total c-Met protein via the lysosomal degradation pathway, inhibiting c-Met-dependent downstream activation and attenuating cellular proliferation in various c-Met-expressing cancer cells. In vivo tumor xenograft models also demonstrated the superior tumor inhibitory responsiveness of IRCR201. Taken together, IRCR201 provides a promising therapeutic agent for c-Met-positive cancer patients through suppressing the c-Met signaling pathway and tumor growth., Competing Interests: The authors declare no conflict of interest.

We developed a homogeneous bridging anti-drug antibody (ADA) assay on an electro chemiluminescent immunoassay (ECLIA) platform to support the immunogenicity evaluation of a dimeric domain antibody (dAb) therapeutic in clinical studies. During method development we evaluated the impact of different types of acid at various pH levels on polyclonal and monoclonal ADA controls of differing affinities and on/off rates. The data shows for the first time that acids of different pH can have a differential effect on ADA of various affinities and this in turn impacts assay sensitivity and drug tolerance as defined by these surrogate controls. Acid treatment led to a reduction in signal of intermediate and low affinity ADA, but not high affinity or polyclonal ADA. We also found that acid pretreatment is a requisite for dissociation of drug bound high affinity ADA, but not for low affinity ADA-drug complexes. Although we were unable to identify an acid that would allow a 100% retrieval of ADA signal post-treatment, use of glycine pH3.0 enabled the detection of low, intermediate and high affinity antibodies (Abs) to various extents. Following optimization, the ADA assay method was validated for clinical sample analysis. Consistencies within various parameters of the clinical data such as dose dependent increases in ADA rates and titers were observed, indicating a reliable ADA method. Pre- and post-treatment ADA negative or positive clinical samples without detectable drug were reanalyzed in the absence of acid treatment or presence of added exogenous drug respectively to further assess the effectiveness of the final acid treatment procedure. The overall ADA results indicate that assay conditions developed and validated based on surrogate controls sufficed to provide a reliable clinical data set. The effect of low pH acid treatment on possible pre-existing ADA or soluble multimeric target in normal human serum was also evaluated, and preliminary data indicate that acid type and pH also affect drug-specific signal differentially in individual samples. The results presented here represent the most extensive analyses to date on acid treatment of a wide range of ADA affinities to explore sensitivity and drug tolerance issues. They have led to a refinement of our current best practices for ADA method development and provide a depth of data to interrogate low pH mediated immune complex dissociation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Despite recent advances in treatment for melanoma patients through using immune checkpoint inhibitors, these monotherapies have limitations and additional treatments have been explored. Type I IFNs have been used to treat melanoma and possess immunomodulatory effects including enhancement of T-cell infiltration. T-cell plays a critical role in immune checkpoint therapies via restoration of effector functions and tumor infiltration by T-cells predicts longer survival in a variety of cancer types. Moreover, tumor-infiltrating T-cells are associated with the expression of chemokines such as CCL5 and CXCR3 ligands in tumor tissues. We therefore investigated whether intratumoral injection of IFN-β induces the expression of CCL5 and CXCR3 ligands in melanoma cells and has additional antitumor effects when combined with anti-PD-L1 mAb treatment. IFN-β treatment enhanced CD8 + T-cell infiltration into tumors and CCL5 and CXCR3 ligand expression. In vivo studies using a mouse model showed that monotherapy with IFN-β, but not with anti-PD-L1 mAb, inhibited tumor growth in comparison to control. However, the therapeutic efficacy of IFN-β was significantly enhanced by the addition of anti-PD-L1 mAb. This antitumor response of combination therapy was abrogated by anti-CD8 mAb and IFN-β augmented the neoantigen-specific T-cell response of anti-PD-L1 mAb. Our findings suggest that IFN-β induces the expression of CCL5 and CXCR3 ligands in melanoma, which could play a role in T-cell recruitment, and enhances the efficacy of anti-PD-L1 mAb treatment in a CD8-dependent manner., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose of Review: This review discusses novel immunotherapeutic approaches to treat Hodgkin lymphoma (HL), specifically PD-1 inhibitors and cellular immunotherapy., Recent Findings: PD-1 inhibitors have shown promising results in the treatment of relapsed or refractory HL, leading to FDA approval of nivolumab and pembrolizumab, although complete remissions are rare. Chimeric antigen receptor T cells directed against CD30 have been investigated with preliminary clinical trials showing minimal toxicities and some responses in heavily pre-treated patients with HL. HL is unique as it consists of a small percentage of malignant cells (Hodgkin Reed Sternberg cells) surrounded by an inflammatory microenvironment which promotes tumor growth and suppresses immune responses, making it an ideal target for immunotherapeutic approaches, such as PD-1 inhibitors and cellular immunotherapy. Current research is focused on overcoming barriers to efficacy via rational combinations that overcome resistance to therapy.

Introduction: Soft tissue sarcomas (STS) are rare malignant tumors. Unfortunately, the first-line doxorubicin-based treatment has not been improved since the 1970s. Platelet-derived growth factor (PDGF) receptor alpha (PDGFR-α) and its ligands are co-expressed in many types of cancer, including sarcomas. They are involved in stimulating growth and regulating stromal-derived fibroblasts and angiogenesis. PDGFR-α and its ligand may play an important role in tumorigenesis and be a potential target in the treatment of sarcomas. Olaratumab is a fully human IgG1-type anti-PDGFR-α monoclonal antibody with a high affinity and a low 50% inhibitory concentration (IC50). Areas covered: The authors review the role of olaratumab in the treatment of STS by focusing on the recent, randomized Phase II JDGD trial that challenged patients with unresectable or metastatic STS with doxorubicin in the presence or absence of olaratumab. This trial showed a great improvement in overall survival (OS), with an increase in survival from 14.7 months to 26.5 months for patients in the experimental arm and showed acceptable toxicity. Expert opinion: Results seem promising. However, it must be qualified, as the study includes several uncertainties. These uncertainties should be addressed by the ongoing Phase 3 JGDJ confirmatory trial, for which the final efficacy analysis is expected by 2019.

Podoplanin is expressed in many cancers, including oral cancers and brain tumors. The interaction between podoplanin and its receptor C-type lectin-like receptor 2 (CLEC-2) has been reported to be involved in cancer metastasis and tumor malignancy. We previously established many monoclonal antibodies (mAbs) against human podoplanin using the cancer-specific mAb (CasMab) technology. LpMab-23 (IgG 1 , kappa), one of the mouse anti-podoplanin mAbs, was shown to be a CasMab. However, we have not shown the usefulness of LpMab-23 for antibody therapy against podoplanin-expressing cancers. In this study, we first determined the minimum epitope of LpMab-23 and revealed that Gly54-Leu64 peptide, especially Gly54, Thr55, Ser56, Glu57, Asp58, Arg59, Tyr60, and Leu64 of podoplanin, is a critical epitope of LpMab-23. We further produced human-mouse chimeric LpMab-23 (chLpMab-23) and investigated whether chLpMab-23 exerts antibody-dependent cellular cytotoxicity (ADCC) and antitumor activity. In flow cytometry, chLpMab-23 showed high sensitivity against a podoplanin-expressing glioblastoma cell line, LN319, and an oral cancer cell line, HSC-2. chLpMab-23 also showed ADCC activity against podoplanin-expressing CHO cells (CHO/podoplanin). In xenograft models with HSC-2 and CHO/podoplanin, chLpMab-23 exerts antitumor activity using human natural killer cells, indicating that chLpMab-23 could be useful for antibody therapy against podoplanin-expressing cancers.

Antibody-drug conjugates (ADCs), which combine the exquisite specificity of antibodies with the cell-killing ability of cytotoxic drug payloads, have emerged as an attractive means for treating cancers. All (pre)clinical ADCs employ biosynthesized cytotoxins as their ADC payload precursors (APPs). The cost-effective bioproduction of APPs is receiving great interest from both academia and industry. Given the lack of systematic overviews of the topic, we provide the current status of APPs and focus on their state-of-the-art bioproduction strategies, illustrated with typical examples and critical analyses. Challenges in further enhancing the bioproduction efficiency of APPs and other cytotoxins are also discussed. This research has implications for bioprocess and metabolic engineering, systems and synthetic biology, and biopharmaceutical drug discovery, development, and industrialization., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. Despite this curative approach, a significant subset of these patients will develop locoregional failure and/or distant metastases. Despite significant progress in the treatment and subsequent prognosis of locally advanced HNSCC, the prognosis of those patients with recurrent and/or metastatic (R/M) HNSCC is poor, with short-lived responses to palliative chemotherapy and few therapeutic agents available. The discovery of the integral role of epidermal growth factor receptor overexpression in the pathogenesis of HNSCC, coupled with emerging data on the role of tumor evasion of the immune system, has opened new pathways in the development of novel therapeutic agents for the treatment of R/M HNSCC. As a result, cetuximab, a monoclonal antibody targeting epidermal growth factor receptor, as well as pembrolizumab and nivolumab, monoclonal antibodies targeting programmed cell death 1 (PD-1), are now US Food and Drug Administration approved for the treatment of R/M HNSCC. This review will detail the data supporting the use of these agents, as well as clinical trials evaluating the efficacy of other novel and promising drugs.

Background: Avelumab (MSB0010718C) is a human IgG1 monoclonal antibody that binds to PD-L1, inhibiting its binding to PD-1, which inactivates T cells. We aimed to establish the safety and pharmacokinetics of avelumab in patients with solid tumours while assessing biological correlatives for future development., Methods: This open-label, single-centre, phase 1a, dose-escalation trial (part of the JAVELIN Solid Tumor trial) assessed four doses of avelumab (1 mg/kg, 3 mg/kg, 10 mg/kg, and 20 mg/kg), with dose-level cohort expansions to provide additional safety, pharmacokinetics, and target occupancy data. This study used a standard 3 + 3 cohort design and assigned patients sequentially at trial entry according to the 3 + 3 dose-escalation algorithm and depending on the number of dose-limiting toxicities during the first 3-week assessment period (the primary endpoint). Patient eligibility criteria included age 18 years or older, Eastern Cooperative Oncology Group performance status 0-1, metastatic or locally advanced previously treated solid tumours, and adequate end-organ function. Avelumab was given as a 1-h intravenous infusion every 2 weeks. Patients in the dose-limiting toxicity analysis set were assessed for the primary endpoint of dose-limiting toxicity, and all patients enrolled in the dose-escalation part were assessed for the secondary endpoints of safety (treatment-emergent and treatment-related adverse events according to National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0), pharmacokinetic and pharmacodynamic profiles (immunological effects), best overall response by Response Evaluation Criteria, and antidrug antibody formation. The population for the pharmacokinetic analysis included a subset of patients with rich pharmacokinetic samples from two selected disease-specific expansion cohorts at the same study site who had serum samples obtained at multiple early timepoints. This trial is registered with ClinicalTrials.gov, number NCT01772004. Patient recruitment to the dose-escalation part reported here is closed., Findings: Between Jan 31, 2013, and Oct 8, 2014, 53 patients were enrolled (four patients at 1 mg/kg, 13 at 3 mg/kg, 15 at 10 mg/kg, and 21 at 20 mg/kg). 18 patients were analysed in the dose-limiting toxicity analysis set: three at dose level 1 (1 mg/kg), three at dose level 2 (3 mg/kg), six at dose level 3 (10 mg/kg), and six at dose level 4 (20 mg/kg). Only one dose-limiting toxicity occurred, at the 20 mg/kg dose, and thus the maximum tolerated dose was not reached. In all 53 enrolled patients (the safety analysis set), common treatment-related adverse events (occurring in >10% of patients) included fatigue (21 patients [40%]), influenza-like symptoms (11 [21%]), fever (8 [15%]), and chills (6 [11%]). Grade 3-4 treatment-related adverse events occurred in nine (17%) of 53 patients, with autoimmune disorder (n=3), increased blood creatine phosphokinase (n=2), and increased aspartate aminotransferase (n=2) each occurring in more than one patient (autoimmune disorder in two patients at 10 mg/kg and one patient at 20 mg/kg, increased blood creatine phosphokinase in two patients at 20 mg/kg, and increased aspartate aminotransferase in one patient at 1 mg/kg, and one patient at 10 mg/kg). Six (11%) of 53 patients had a serious treatment-related adverse event: autoimmune disorder (two [13%]), lower abdominal pain (one [7%]), fatigue (one [7%]), and influenza-like illness (one [7%]) in three patients treated at 10 mg/kg dose level, and autoimmune disorder (one [5%]), increased amylase (one [5%]), myositis (one [5%]), and dysphonia (one [5%]) in three patients who received the 20 mg/kg dose. We recorded some evidence of clinical activity in various solid tumours, with partial confirmed or unconfirmed responses in four (8%) of 53 patients; 30 (57%) additional patients had stable disease. Pharmacokinetic analysis (n=86) showed a dose-proportional exposure between doses of 3 mg/kg and 20 mg/kg and a half-life of 95-99 h (3·9-4·1 days) at the 10 mg/kg and 20 mg/kg doses. Target occupancy was greater than 90% at doses of 3 mg/kg and 10 mg/kg. Antidrug antibodies were detected in two (4%) of 53 patients. No substantial differences were found in absolute lymphocyte count or multiple immune cell subsets, including those expressing PD-L1, after treatment with avelumab. 31 (58%) of 53 patients in the overall safety population died; no deaths were related to treatment on study., Interpretation: Avelumab has an acceptable toxicity profile up to 20 mg/kg and the maximum tolerated dose was not reached. Based on pharmacokinetics, target occupancy, and immunological analysis, we chose 10 mg/kg every 2 weeks as the dose for further development and phase 3 trials are ongoing., Funding: National Cancer Institute and Merck KGaA., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Introduction: Immune checkpoint inhibition holds great promise for selected tumors. The human monoclonal antibody (mAB) avelumab is directed to programmed death ligand-1 (PD-L1) and is supposed to inhibit the immunosuppressive PD-L1/PD-1 interaction and, furthermore, effect antibody-dependent cytotoxicity (ADCC) lysis of tumor cells. Areas covered: This article presents an overview of the current means to activate the antitumor immune defense by targeting PD-1 or PD-L1 with mABs and their possible role in ADCC-mediated tumor cell elimination. Expert opinion: Avelumab contains a Fc region which can bind cognate receptors on immune effector cells and induce ADCC-mediated tumor cell lysis, in contrast to other mABs directed to PD-1/PD-L1 which lack the ability to trigger ADCC due to belonging to the IgG4 subclass or possessing a mutated Fc region. Preclinical and clinical data indicate that avelumab can be safely administered to cancer patients with a toxicity profile comparable to other mABs and without lysis of PD-L1-positive activated immune cells. This antibody yielded durable responses in a phase II trial in advanced Merkel cell carcinoma patients. Tumor cell lysis by avelumab prevents cells from resorting to alternative checkpoints as shown by targeting PD-1 and the upregulation of TIM-3.

Nivolumab is a fully human IgG4 monoclonal antibody targeting the programmed death-1 (PD-1) receptor that blocks interactions between PD-1 and its ligands on tumor cells to prevent T-cell exhaustion in patients with cancer. It has demonstrated efficacy in multiple tumor types, including melanoma, non-small-cell lung cancer, and renal cell carcinoma. This analysis assessed the immunogenicity of nivolumab and its impact on pharmacokinetics, safety, and efficacy in patients with solid tumors enrolled in 6 clinical studies. The incidence and prevalence of antidrug antibodies (ADAs) were determined by validated electrochemiluminescence assays in samples collected during nivolumab treatment and up to 100 days after the last dose. Confirmed positive samples from the 6 studies were also tested for presence of neutralizing antibodies (NAbs). Among 1086 nivolumab-treated patients, 138 patients (12.7%) were ADA positive (relative to baseline), only 3 (0.3%) of whom were persistently positive for ADA, and 9 (0.8%) were NAb positive at 1 time point. The presence of ADAs was not associated with hypersensitivity, infusion reactions, or loss of efficacy and had minimal impact on nivolumab clearance. Additionally, the presence of NAbs was not associated with loss of efficacy. In conclusion, immunogenicity of nivolumab is not clinically meaningful., (© 2016, The American College of Clinical Pharmacology.)

The interaction between podoplanin (PDPN) and C-type lectin-like receptor 2 (CLEC-2) is involved in tumor malignancy. We have established many monoclonal antibodies (mAbs) against human podoplanin using the cancer-specific mAb (CasMab) technology. LpMab-21, one of the mouse antipodoplanin mAbs, is of the IgG 2a subclass, and its minimum epitope was determined to be Thr76-Arg79 of the human podoplanin. Importantly, sialic acid is linked to Thr76; therefore, LpMab-21 is an antiglycopeptide mAb (GpMab). In this study, we investigated whether LpMab-21 shows antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) against human podoplanin-expressing cancer cell lines in vitro and also studied its antitumor activities using a xenograft model. LpMab-21 showed high ADCC and CDC activities against not only podoplanin-expressing Chinese hamster ovary cells but also LN319 glioblastoma cells and PC-10 lung cancer cells, both of which endogenously express podoplanin. Furthermore, LpMab-21 decreased tumor growth in vivo, indicating that LpMab-21 could be useful for antibody therapy against human podoplanin-expressing cancers.

Background: Multiple Myeloma (MM) cells inhibit the development of an effective anti- MM immune response via defects in T cell function, ineffective antigen presentation; reduced phagocytic capacity; natural killer and dendritic cell dysfunction; decreased responsiveness to IL-2 and defects in B cell immunity; upregulation of inhibitory pathways; and production of excessive proinflammatory cytokines. Moreover, immune cells including plasmacytoid dendritic cells and macrophages trigger tumor cell proliferation, survival, and drug resistance. The usefulness of immunotherapies in MM patients has first been supported by the identification of the graft-versus-myeloma effect in the context of allogeneic bone marrow (BM) transplantation. Subsequently, the inclusion of thalidomide and its derivatives, the Immunomodulatory Drugs (IMiDs) as well as of (immuno) proteasome inhibitors into MM regimens dramatically improved MM patients outcome during the last 15 years. Despite these unprecedented therapeutic advances MM remains an incurable disease., Objective: This article reviews novel immunotherapeutic approaches, which aim to restore the balance within the immunologic niche of the MM BM microenvironment., Method: A systematic search was conducted of the Pubmed Medline, Embase, and Cochrane Library databases for primary articles, as well as of conference abstracts (e.g., of the American Society of Hematology, the American Society of Clinical Oncology, the American Association of Cancer Research, the European Hematology Association, and the Multiple Myeloma Workshop), practice guidelines, and registries of clinical trials., Results: The inclusion of monoclonal antibodies, immune checkpoint inhibitors, chimeric antigen receptor-engineered (CAR) T cells, genetically engineered T cells, and vaccination, dendritic cellbased cancer vaccines in particular, into existing regimens is likely to significantly improve MM patient outcome in the near future., Conclusion: Given continuing efforts to target the immune niche within the bone marrow microenvironment we are confident that the rise of immunotherapies in MM will result in long-lasting responses in many of our patients within the next decade., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

The programmed cell death-1 receptor (PD-1) is an immune checkpoint inhibitor which is expressed on the surface of immune effector cells. It is activated mainly by PD-L1 which can be expressed by all human cells. The PD-1/PD-L1 pathway plays a subtle role in maintaining peripheral T-lymphocyte tolerance and regulating inflammation. In cancer, the expression of PD-L1 seems to be one of the major immune escape mechanisms. Many studies have shown efficacy of blocking PD-1 or PD-L1 with specific antibodies like pembrolizumab or atezulizumab. In breast cancer, potential response was demonstrated in metastatic triple-negative breast cancers., (© 2017 S. Karger GmbH, Freiburg.)

Monoclonal antibody-based treatment of cancer has been established as one of the most successful therapeutic strategies for both hematologic malignancies and solid tumors. In addition to targeting cancer antigens antibodies can also modulate immunological pathways that are critical to immune surveillance. Antibody therapy directed against several negative immunologic regulators (checkpoints) is demonstrating significant success in the past few years. Immune checkpoint inhibitors, ipilimumab, pembrolizumab and nivolumab, have shown significant clinical benefit in several malignancies and are already approved for advanced melanoma and squamous NSCLC. Based on their mechanism of action, these agents can exert toxicities that are unlike conventional cytotoxic chemotherapy, whose nature is close to autoimmune diseases - immune related adverse events (irAEs). In this review we focus on the spectrum of irAEs associated with immune checkpoint antibodies, discussing the pharmacological treatment strategy and possible clinical impact.

Purpose: Nivolumab, an anti-PD-1 immune checkpoint inhibitor, improved overall survival versus everolimus in a phase 3 trial of previously treated patients with metastatic renal cell carcinoma (mRCC). We investigated immunomodulatory activity of nivolumab in a hypothesis-generating prospective mRCC trial., Experimental Design: Nivolumab was administered intravenously every 3 weeks at 0.3, 2, or 10 mg/kg to previously treated patients and 10 mg/kg to treatment-naïve patients with mRCC. Baseline and on-treatment biopsies and blood were obtained. Clinical activity, tumor-associated lymphocytes, PD-L1 expression (Dako immunohistochemistry; ≥5% vs. <5% tumor membrane staining), tumor gene expression (Affymetrix U219), serum chemokines, and safety were assessed., Results: In 91 treated patients, median overall survival [95% confidence interval (CI)] was 16.4 months [10.1 to not reached (NR)] for nivolumab 0.3 mg/kg, NR for 2 mg/kg, 25.2 months (12.0 to NR) for 10 mg/kg, and NR for treatment-naïve patients. Median percent change from baseline in tumor-associated lymphocytes was 69% (CD3 + ), 180% (CD4 + ), and 117% (CD8 + ). Of 56 baseline biopsies, 32% had ≥5% PD-L1 expression, and there was no consistent change from baseline to on-treatment biopsies. Transcriptional changes in tumors on treatment included upregulation of IFNγ-stimulated genes (e.g., CXCL9). Median increases in chemokine levels from baseline to C2D8 were 101% (CXCL9) and 37% (CXCL10) in peripheral blood. No new safety signals were identified., Conclusions: Immunomodulatory effects of PD-1 inhibition were demonstrated through multiple lines of evidence across nivolumab doses. Biomarker changes from baseline reflect nivolumab pharmacodynamics in the tumor microenvironment. These data may inform potential combinations. Clin Cancer Res; 22(22); 5461-71. ©2016 AACR., (©2016 American Association for Cancer Research.)

Immunocytokines (antibody-cytokine fusions) have been proved to be a promising class of therapeutic agents for tumors. Anti-PD-L1 antibodies or IL-2 have been used to treat a variety of cancers. Here, in order to remove T cell inhibition and increasing the IL-2 concentration in the tumor microenvironment, we engineered a novel anti-PD-L1 antibody based immunocytokine by fusing hIL-2 to the C-Term of atezolizumab, denoted as BIPI. Our results revealed that BIPI was effective in stimulating T cell activation in vitro and could selectively localize to the tumor. Furthermore, tumor regression and prolonged survival were also observed in the metastatic colorectal cancer mouse model. The obviously longer survival mice in BIPI treatment group turned out depending on the function of CD8 + T cells. The IFN- secreted from CD8 + T cells in the spleen also contributed to the better tumor inhibition profile in BIPI treatment group than in anti-PD-L1 or IL-2 treatment alone. Taken together, our data evidenced the enhanced antitumor potency of BIPI, suggesting its potential use for cancers with a low response to the anti-PD-L1 or IL-2 treatment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The anti-ErbB2 humanized antibody trastuzumab was approved for ErbB2-positive metastatic gastric and gastro-esophageal junction cancer in 2010. Despite the effectiveness of trastuzumab, its efficacy remains variable and often modest. Thus, there is an urgent need to improve ErbB2-targeting therapy. Down-regulation of surface receptors induced by monoclonal antibody (mAb) contributes to its antitumor efficacy. Previous studies have demonstrated that if two anti-ErbB2 mAbs did not compete with each other for binding to ErbB2, the combination of them can enhance ErbB2 internalization. In the present study, we investigated ErbB2 internalization-inducing ability of non-competitive anti-ErbB2 mAb combinations and surprisingly found that most of the mAb combinations tested did not down-regulate ErbB2. Only 4 of 18 non-competitive mAb pairs efficiently induced ErbB2 internalization. Interestingly, although the non-competitive anti-ErbB2 mAbs trastuzumab and pertuzumab, either alone or in combination, were ineffective at inducing ErbB2 internalization, TPL, a bispecific antibody engineered from trastuzumab and pertuzumab, potently down-regulated the ErbB2 molecule. Importantly, TPL exhibited a far greater antitumor effect on ErbB2-overexpressing gastric cancer cell line than trastuzumab plus pertuzumab, suggesting that it may be a promising agent for the treatment of gastric cancer., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Galectins are carbohydrate binding proteins that function in many key cellular processes. We have previously demonstrated that galectins are essential for tumor angiogenesis and their expression is associated with disease progression. Targeting galectins is therefore a potential anti-angiogenic and anti-cancer strategy. Here, we used a rational approach to generate antibodies against a specific member of this conserved protein family, i.e. galectin-1. We characterized two novel mouse monoclonal antibodies that specifically react with galectin-1 in human, mouse and chicken. We demonstrate that these antibodies are excellent tools to study galectin-1 expression and function in a broad array of biological systems. In a potential diagnostic application, radiolabeled antibodies showed specific targeting of galectin-1 positive tumors. In a therapeutic setting, the antibodies inhibited sprouting angiogenesis in vitro and in vivo, underscoring the key function of galectin-1 in this process., (© 2016 UICC.)

Checkpoint inhibitors such as nivolumab represent a novel class of agents that are being increasingly used in the treatment of various cancers. Their toxicities represent unique challenges to the oncologists prescribing them, patients' primary care physicians and other specialists who may encounter these patients during consultations. It is important for physicians to remain vigilant and include autoimmune toxicities in the list of potential differential diagnoses in patients receiving novel cancer therapeutics who present with unusual toxicities. We report the unusual case of a 68-year-old woman with advanced lung cancer on the novel chemotherapeutic Nivolumab whom we suspect developed autoimmune myocarditis with significant cardiac conduction disease as an unintended, and as of yet unrecognised, side effect from this medication., (2016 BMJ Publishing Group Ltd.)

Purpose: CEA TCB is a novel IgG-based T-cell bispecific (TCB) antibody for the treatment of CEA-expressing solid tumors currently in phase I clinical trials (NCT02324257). Its format incorporates bivalent binding to CEA, a head-to-tail fusion of CEA- and CD3e-binding Fab domains and an engineered Fc region with completely abolished binding to FcγRs and C1q. The study provides novel mechanistic insights into the activity and mode of action of CEA TCB., Experimental Design: CEA TCB activity was characterized on 110 cell lines in vitro and in xenograft tumor models in vivo using NOG mice engrafted with human peripheral blood mononuclear cells., Results: Simultaneous binding of CEA TCB to tumor and T cells leads to formation of immunologic synapses, T-cell activation, secretion of cytotoxic granules, and tumor cell lysis. CEA TCB activity strongly correlates with CEA expression, with higher potency observed in highly CEA-expressing tumor cells and a threshold of approximately 10,000 CEA-binding sites/cell, which allows distinguishing between high- and low-CEA-expressing tumor and primary epithelial cells, respectively. Genetic factors do not affect CEA TCB activity confirming that CEA expression level is the strongest predictor of CEA TCB activity. In vivo, CEA TCB induces regression of CEA-expressing xenograft tumors with variable amounts of immune cell infiltrate, leads to increased frequency of activated T cells, and converts PD-L1 negative into PD-L1-positive tumors., Conclusions: CEA TCB is a novel generation TCB displaying potent antitumor activity; it is efficacious in poorly infiltrated tumors where it increases T-cell infiltration and generates a highly inflamed tumor microenvironment. Clin Cancer Res; 22(13); 3286-97. ©2016 AACR., (©2016 American Association for Cancer Research.)

Purpose of Review: The aim of this review is to draw the attention of the physicians and oncologists on the rare side-effects of checkpoint inhibitors not usually reported in clinical trials to treat them quickly and render their prognosis better., Recent Findings: Rare side-effects of checkpoint inhibitors are mainly neurologic, haematologic, rheumatologic, renal, and cardiac. The majority of reported side-effects are consequent of the treatment by ipilimumab in patients diagnosed with melanomas. Neurologic side-effects have poorer prognosis compared with other rare side-effects. There is no relationship between developing rare side-effects and the outcome of the disease., Summary: It is important to be aware, when treating patients with checkpoint inhibitors, to detect as early as possible the unpredictable and uncontrollable rare side-effects of these agents. The large spectrum of these rare side-effects should be well documented and reported to assure to the physicians a road map for the diagnosis and the management of these toxicities.