Oncternal presents interim data from Phase 1b clinical study of cirmtuzumab
Oncternal Therapeutics announced the presentation of interim data from the ongoing, investigator-sponsored Phase 1b clinical study of cirmtuzumab, its investigational anti-ROR1 monoclonal antibody, in combination with paclitaxel in patients with HER2-negative, metastatic or locally-advanced unresectable breast cancer. The results were presented at the San Antonio Breast Cancer Symposium in San Antonio, TX. As of the data cut-off date of November 27, 2019, a total of eight patients with HER2-negative, metastatic or locally-advanced unresectable breast cancer were enrolled in the study. Seven of the eight patients were evaluable for safety and efficacy. Four of the patients had triple negative breast cancer at study enrollment. Four of the seven evaluable patients achieved a partial response, for an objective response rate of 57%, including one partial response that continued on cirmtuzumab alone for 30 weeks after discontinuing paclitaxel. The combination of cirmtuzumab and paclitaxel has been well tolerated in this trial, with no study discontinuations for toxicity and no dose-limiting toxicities observed to date. Adverse events have been consistent with the known safety profile of paclitaxel alone. Pharmacokinetic analysis of serial plasma samples for free unbound antibody from two patients provided results similar to those observed in previous studies of chronic lymphocytic leukemia patients, consistent with a projected half-life of 30 days. No decline in antibody concentration over time was observed, consistent with the absence of neutralizing antibodies. "It is encouraging to see that cirmtuzumab in combination with paclitaxel has been well tolerated and is active. Future studies will determine whether cirmtuzumab is contributing to the known activity of paclitaxel. Advanced breast cancer patients are in need of improved treatment options with acceptable side effects. We look forward to completing enrollment and treating additional patients in this study," said Rebecca Shatsky, M.D., Assistant Clinical Professor, Medicine at University of California San Diego School of Medicine, lead investigator.