MEN1309/OBT076, a First-In-Class Antibody-Drug Conjugate Targeting CD205 in Solid Tumors.

CD205 is a type I transmembrane glycoprotein and is a member of the C-type lectin receptor family. Analysis by mass spectrometry revealed that CD205 was robustly expressed and highly prevalent in a variety of solid malignancies from different histotypes. IHC confirmed the increased expression of CD205 in pancreatic, bladder, and triple-negative breast cancer (TNBC) compared with that in the corresponding normal tissues. Using immunofluorescence microscopy, rapid internalization of the CD205 antigen was observed. These results supported the development of MEN1309/OBT076, a fully humanized CD205-targeting mAb conjugated to DM4, a potent maytansinoid derivate, via a cleavable N-succinimidyl-4-(2-pyridyldithio) butanoate linker. MEN1309/OBT076 was characterized in vitro for target binding affinity, mechanism of action, and cytotoxic activity against a panel of cancer cell lines. MEN1309/OBT076 displayed selective and potent cytotoxic effects against tumor cells exhibiting strong and low to moderate CD205 expression. In vivo, MEN1309/OBT076 showed potent antitumor activity resulting in durable responses and complete tumor regressions in many TNBC, pancreatic, and bladder cancer cell line-derived and patient-derived xenograft models, independent of antigen expression levels. Finally, the pharmacokinetics and pharmacodynamic profile of MEN1309/OBT076 was characterized in pancreatic tumor-bearing mice, demonstrating that the serum level of antibody-drug conjugate (ADC) achieved through dosing was consistent with the kinetics of its antitumor activity. Overall, our data demonstrate that MEN1309/OBT076 is a novel and selective ADC with potent activity against CD205-positive tumors. These data supported the clinical development of MEN1309/OBT076, and further evaluation of this ADC is currently ongoing in the first-in-human SHUTTLE clinical trial.

Considerations for the nonclinical safety evaluation of antibody drug conjugates for oncology.

Antibody drug conjugates (ADCs) include monoclonal antibodies that are linked to cytotoxic small molecules. A number of these agents are currently being developed as anti-cancer agents designed to improve the therapeutic index of the cytotoxin (i.e., cytotoxic small molecule or cytotoxic agent) by specifically delivering it to tumor cells. This paper presents primary considerations for the nonclinical safety evaluation of ADCs and includes strategies for the evaluation of the entire ADC or the various individual components (i.e., antibody, linker or the cytotoxin). Considerations are presented on how to design a nonclinical safety assessment program to identify the on- and off-target toxicities to enable first-in-human (FIH) studies. Specific discussions are also included that provide details as to the need and how to conduct the studies for evaluating ADCs in genetic toxicology, tissue cross-reactivity, safety pharmacology, carcinogenicity, developmental and reproductive toxicology, biotransformation, toxicokinetic monitoring, bioanalytical assays, immunogenicity testing, test article stability and the selection of the FIH dose. Given the complexity of these molecules and our evolving understanding of their properties, there is no single all-encompassing nonclinical strategy. Instead, each ADC should be evaluated on a case-by-case scientifically-based approach that is consistent with ICH and animal research guidelines.

CYP3A-mediated drug-drug interaction potential and excretion of brentuximab vedotin, an antibody-drug conjugate, in patients with CD30-positive hematologic malignancies.

Brentuximab vedotin is an antibody-drug conjugate (ADC) that selectively delivers monomethyl auristatin E (MMAE) into CD30-expressing cells. This study evaluated the CYP3A-mediated drug-drug interaction potential of brentuximab vedotin and the excretion of MMAE. Two 21-day cycles of brentuximab vedotin (1.2 or 1.8 mg/kg intravenously) were administered to 56 patients with CD30-positive hematologic malignancies. Each patient also received either a sensitive CYP3A substrate (midazolam), an effective inducer (rifampin), or a strong inhibitor (ketoconazole). Brentuximab vedotin did not affect midazolam exposures. ADC exposures were unaffected by concomitant rifampin or ketoconazole; however, MMAE exposures were lower with rifampin and higher with ketoconazole. The short-term safety profile of brentuximab vedotin in this study was generally consistent with historic clinical observations. The most common adverse events were nausea, fatigue, diarrhea, headache, pyrexia, and neutropenia. Over a 1-week period, ∼23.5% of intact MMAE was recovered after administration of brentuximab vedotin; all other species were below the limit of quantitation. The primary excretion route is via feces (median 72% of the recovered MMAE). These results suggest that brentuximab vedotin (1.8 mg/kg) and MMAE are neither inhibitors nor inducers of CYP3A; however, MMAE is a substrate of CYP3A.

Brentuximab vedotin (SGN-35) for relapsed CD30-positive lymphomas.

BACKGROUND: Hodgkin's lymphoma and anaplastic large-cell lymphoma are the two most common tumors expressing CD30. Previous attempts to target the CD30 antigen with monoclonal-based therapies have shown minimal activity. To enhance the antitumor activity of CD30-directed therapy, the antitubulin agent monomethyl auristatin E (MMAE) was attached to a CD30-specific monoclonal antibody by an enzyme-cleavable linker, producing the antibody-drug conjugate brentuximab vedotin (SGN-35). METHODS: In this phase 1, open-label, multicenter dose-escalation study, we administered brentuximab vedotin (at a dose of 0.1 to 3.6 mg per kilogram of body weight) every 3 weeks to 45 patients with relapsed or refractory CD30-positive hematologic cancers, primarily Hodgkin's lymphoma and anaplastic large-cell lymphoma. Patients had received a median of three previous chemotherapy regimens (range, one to seven), and 73% had undergone autologous stem-cell transplantation. RESULTS: The maximum tolerated dose was 1.8 mg per kilogram, administered every 3 weeks. Objective responses, including 11 complete remissions, were observed in 17 patients. Of 12 patients who received the 1.8-mg-per-kilogram dose, 6 (50%) had an objective response. The median duration of response was at least 9.7 months. Tumor regression was observed in 36 of 42 patients who could be evaluated (86%). The most common adverse events were fatigue, pyrexia, diarrhea, nausea, neutropenia, and peripheral neuropathy. CONCLUSIONS: Brentuximab vedotin induced durable objective responses and resulted in tumor regression for most patients with relapsed or refractory CD30-positive lymphomas in this phase 1 study. Treatment was associated primarily with grade 1 or 2 (mild-to-moderate) toxic effects. (Funded by Seattle Genetics; ClinicalTrials.gov number, NCT00430846.).

Practical considerations for nonclinical safety evaluation of therapeutic monoclonal antibodies.

Monoclonal antibodies (mAbs) are a well established class of therapeutics as evidenced by a large number of FDA approved mAbs for the treatment of cancers and autoimmune diseases. Monoclonal antibodies that are molecularly engineered for enhanced functions and pharmacokinetic properties are routinely being considered for development by many biotechnology companies. Safety evaluation of current generation of mAbs poses new challenges due to the highly complex nature of engineering aspects and variability induced by the diverse recombinant cell systems to generate them. This review provides a basic outline for nonclinical safety evaluation of therapeutic antibodies. Important considerations for planning a preclinical program, the types of nonclinical safety studies, and a general timeline for their conduct in relation to clinical trials are described. A list of relevant regulatory documents issued by government agencies is also provided. Adoption of these principles will greatly enhance the quality and relevance of the nonclinical safety data generated and will facilitate future development of mAb therapeutics.