MOR209/ES414, a Novel Bispecific Antibody Targeting PSMA for the Treatment of Metastatic Castration-Resistant Prostate Cancer.

Treatment of metastatic, castration-resistant prostate cancer (mCRPC) remains a highly unmet medical need and current therapies ultimately result in disease progression. Immunotherapy is a rapidly growing approach for treatment of cancer but has shown limited success to date in the treatment of mCRPC. We have developed a novel humanized bispecific antibody, MOR209/ES414, built on the ADAPTIR (modular protein technology) platform, to redirect T-cell cytotoxicity toward prostate cancer cells by specifically targeting T cells through CD3ε to prostate cancer cells expressing PSMA (prostate-specific membrane antigen). In vitro cross-linking of T cells with PSMA-expressing tumor cells by MOR209/ES414 triggered potent target-dependent tumor lysis and induction of target-dependent T-cell activation and proliferation. This activity occurred at low picomolar concentrations of MOR209/ES414 and was effective at low T-effector to tumor target cell ratios. In addition, cytotoxic activity was equivalent over a wide range of PSMA expression on target cells, suggesting that as few as 3,700 PSMA receptors per cell are sufficient for tumor lysis. In addition to high sensitivity and in vitro activity, MOR209/ES414 induced limited production of cytokines compared with other bispecific antibody formats. Pharmacokinetic analysis of MOR209/ES414 demonstrated a serum elimination half-life in NOD/SCID γ (NSG) mice of 4 days. Administration of MOR209/ES414 in murine xenograft models of human prostate cancer significantly inhibited tumor growth, prolonged survival, and decreased serum prostate-specific antigen levels only in the presence of adoptively transferred human T cells. On the basis of these preclinical findings, MOR209/ES414 warrants further investigation as a potential therapeutic for the treatment of CRPC. Mol Cancer Ther; 15(9); 2155-65. ©2016 AACR.

A phase 1 study evaluating the safety and tolerability of otlertuzumab, an anti-CD37 mono-specific ADAPTIR therapeutic protein in chronic lymphocytic leukemia.

Otlertuzumab is a novel humanized anti-CD37 protein therapeutic. This study evaluated the safety of otlertuzumab administered intravenously to patients with chronic lymphocytic leukemia (CLL). Otlertuzumab was administered weekly for up to 8 weeks followed by 1 dose per month for 4 months ranging from 0.03 to 20 mg/kg in the dose-escalation phase and 10 to 30 mg/kg in the dose-expansion phase. Responses were determined by using the 1996 National Cancer Institute (NCI-96) and 2008 International Workshop on Chronic Lymphocytic Leukaemia (IWCLL) criteria. Fifty-seven patients were treated in the dose-escalation phase and 26 in the dose-expansion phase. A maximum-tolerated dose was not identified. Response occurred in 19 (23%) of 83 treated patients by NCI-96 criteria. All responses were partial and occurred more commonly in patients with symptomatic untreated CLL (6/7) or 1 to 2 prior therapies (12/28) vs 3 or more therapies (1/48). Twenty percent (12/61) with serial computed tomography scan assessment had a response per IWCLL criteria. The most frequent adverse events were infusion reactions, fatigue, nausea, and diarrhea and were not dose related. Otlertuzumab was well tolerated, and modest clinical activity was observed. Otlertuzumab warrants further evaluation in combination with other agents for the treatment of CLL. This trial was registered at www.clinicaltrials.gov as #NCT00614042.

Pharmacokinetic and pharmacodynamic properties of TRU-015, a CD20-directed small modular immunopharmaceutical protein therapeutic, in patients with rheumatoid arthritis: a Phase I, open-label, dose-escalation clinical study.

BACKGROUND: TRU-015 is a small modular immunopharmaceutical protein drug that binds to CD20 and effectively depleted B cells in nonhuman primates. OBJECTIVE: The aim of this clinical study was to determine the pharmacokinetic (PK) and pharmacodynamic (PD) properties, immunogenicity, and tolerability of TRU-015 in patients with rheumatoid arthritis (RA). METHODS: This Phase I, open-label, dose-escalation clinical study was conducted at 4 medical centers in the United States. Patients with RA who were receiving stable-dose methotrexate were enrolled in 1 of 8 dose groups and received TRU-015 as a single IV dose of 0.015, 0.05, 0.15, 0.5, 1.5, 5, or 15, or 2 IV doses of 15 mg/kg, administered 7 days apart (30 mg/kg). Patients were enrolled in the next higher dose cohort based on the tolerability observed in the prior cohort. Prior to TRU-015 infusion, patients were premedicated with an antihistamine and acetaminophen and may have received a corticosteroid at the investigator's discretion. Serum samples were collected for analysis of PK properties (serum t((1/2))) and neutralizing antibodies to TRU-015; enzyme-linked immunosorbent assays and a cell-based neutralizing assay were used to evaluate samples from patients. PD response was measured using B-cell (CD19(+)-cell) count using flow cytometry at prespecified time points. Tolerability was assessed during drug infusion and at prespecified time points after infusion using physical examination and laboratory analysis. Patients were followed for >or=4 weeks and until B-cell recovery. RESULTS: Thirty-seven patients were enrolled. Most were female (81%) and white (95%); the mean age was 53 years. Serum t((1/2)) ranged from 12 to 19 days. B-cell depletion generally increased in degree and duration with increasing doses. No neutralizing antibodies to TRU-015 were detected. Mild adverse events (AEs) included back pain, headache, peripheral edema, and upper respiratory infection (5 patients each). Mild urticaria occurred in 1 patient. Grade 3 AEs included hypertension, arthralgia, and urticaria and bronchospasm (1 patient each). No dose-limiting toxicity was found. CONCLUSIONS: In this small population of patients with RA, the C(max) and the AUC appeared to increase in a dose-proportional manner. The mean t((1/2)) ranged from 12 to 19 days. TRU-015 was associated with dose-dependent B-cell depletion and an acceptable tolerability profile.

Characterization of a proapoptotic antiganglioside GM2 monoclonal antibody and evaluation of its therapeutic effect on melanoma and small cell lung carcinoma xenografts.

Monoclonal antibodies have begun to show great clinical promise for the treatment of cancer. Antibodies that can directly affect a tumor cell's growth and/or survival are of particular interest for immunotherapy. Previously, we described monoclonal antibody DMF10.62.3 that had antiproliferative and proapoptotic effects when it bound an antigen of unknown identity on tumor cells in vitro. In this report, we determined that DMF10.62.3 and a clonally related antibody DMF10.167.4 recognize the ganglioside GM2. These antibodies react with a GM2 epitope that is expressed on a large number of tumor cell lines, including human melanoma and small cell lung carcinoma, but not on normal primary lines or most normal tissues. Interestingly, this pattern of cellular reactivity is distinct from that reported for other previously described GM2 antibodies, a difference that is presumably due to DMF10.167.4's binding to a unique GM2-associated epitope. Additional characterization of DMF10.167.4 revealed that this antibody was able to induce apoptosis and/or block cellular proliferation when cultured in vitro with the human Jurkat T lymphoma, CHL-1 melanoma, and SBC-3 small cell lung carcinoma lines. In vivo, DMF10.167.4 antibody was well tolerated in mice and did not detectably bind to or damage normal tissues. However, this antibody was able to prevent murine E710.2.3 lymphoma, human CHL-1 melanoma, and SBC-3 small cell lung carcinoma lines from establishing tumors in vivo and blocked progression of established CHL-1 and SBC-3 tumors in vivo. Therefore, monoclonal antibody DMF10.167.4 has immunotherapeutic potential.