On June 5, 2017 MabVax Therapeutics Holdings, Inc. (Nasdaq: MBVX), a clinical-stage biotechnology company with a fully human antibody discovery platform focused on the rapid translation into clinical development of products to address unmet medical needs in the treatment of cancer, reported results from its Phase I clinical trial of MabVax’s therapeutic antibody MVT-5873, being evaluated to treat patients with advanced pancreatic cancer and other CA19-9 positive cancers in a poster presentation at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting on June 3, 2017 (Press release, MabVax, JUN 5, 2017, View Source [SID1234519443]). The Company highlighted that the single agent MVT-5837 appears safe and well tolerated in patients at biologically active doses. Further, all patients were evaluated by RECIST 1.1 for tumor response, and the Company reported one patient achieved a complete response and 11 more patients achieved stable disease in this dose escalation safety trial of 32 patients. Schedule your 30 min Free 1stOncology Demo!
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"The results of our Phase Ia trial with MVT-5873 indicate that we have a fully-human antibody targeting CA19-9 cancers that can be administered at doses with acceptable safety and with a potentially positive impact on disease. CA19-9 is broadly expressed in various cancers including pancreatic, colon, and small cell lung cancer making this antibody potentially useful for a larger patient population. The early efficacy signals from an identifiable subset of subjects has enabled us to understand those patients most likely to respond to MVT-5873 based therapy. At the maximum tolerated dose (MTD) we have established in this trial, we have demonstrated an acceptable safety margin and have cleared the way for MVT-5873 in combination with our immunoPET imaging agent (MVT-2163) and Radioimmunotherapy (MVT-1075) which are currently in phase I clinical trials," said David Hansen, President and CEO of MabVax.
The recently completed Phase Ia trial was an open-label, dose-escalation study evaluating the safety, tolerability and pharmacokinetics of MVT-5873 as a single-agent in patients with locally advanced or metastatic pancreatic or colon cancer who had failed all prior therapies and regressed into progressive disease. Secondary endpoints included evaluation of tumor response by RECIST 1.1 and duration of response. A second arm of the Company’s MVT-5873 Phase Ia trial is actively evaluating MVT-5873 in combination with gemcitabine plus nab-paclitaxel in newly diagnosed pancreatic cancer patients. Dr. Eileen O’Reilly, Associate Director of the David M. Rubenstein Center for Pancreatic Cancer Research, attending physician, member at Memorial Sloan Kettering Cancer Center and Professor of Medicine at Weill Cornell Medical College is the lead investigator in the MVT-5873 Phase I clinical trial.
Safe and Tolerable Dose Established
MVT-5873 was administered in both weekly and every other week dosing schedules. A maximum tolerated dose (MTD) was determined at 1 mg/kg with both dosing schedules. Dose limiting toxicities (DLTs) with single-agent MVT-5873 were reversible increases in liver function tests, that occurred early in Cycle 1 of therapy and typically resolved within a week. Most patients experiencing DLT events were able to continue therapy at a reduced dose. Infusion reactions were mitigated with the use of premedication and extended infusion times. To date, there has been no evidence that MVT-5873 induces antibody-drug-antibodies (ADA) in treated patients.
Potential Efficacy Signal Observed in Patients
The levels of serum tumor marker CA19-9 are considered a valuable adjunct in the diagnosis, prognosis and monitoring of treatment of pancreatic cancer. Treatment with MVT-5873 normally results in a decrease in the serum tumor marker CA19-9 levels immediately following administration. After completing the first treatment Cycle, lasting 28 days, forty percent of patients had a sustained decrease in CA19-9 levels of greater than or equal to 50%. Patients with a greater than or equal to 50% reduction in CA19-9 levels continued treatment for a median of four cycles (range 2 to 9.75+), compared to one cycle (range 0.25 to 3) for patients with less than 50% decrease. Twelve of thirty-two patients achieved a stable disease (SD) response as determined by RECIST 1.1 measurements made every second cycle of therapy. One patient achieved a complete response (CR) by the first RECIST 1.1 time point at the end of the second cycle.
"Combining the results from our MVT-5873 single agent trial and our MVT-2163 immunoPET trial, whose Phase 1a results will be announced at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) annual meeting held June 10-14, 2017, gives us an opportunity to enrich patient selection for our upcoming clinical trials. We think there is a place for MVT-5873 in the treatment of CA19-9 expressing cancers including in combination with a standard of care chemotherapy for newly diagnosed treatment naïve patients. MVT-5873 is being evaluated in combination with gemcitabine and nab-paclitaxel in a second arm of this Phase I trial and we anticipate results to be available later this year. We continue to be focused on bringing more potent MVT-5873-based products into the clinic. The first of these more potent products is our radioimmunotherapy agent MVT-1075 for which we plan to initiate the Phase I trial this month," continued Mr. Hansen.