SELLAS Life Sciences Group Inc. (NASDAQ: SLS) dropped 15.07% after the company released initial immunobiological and clinical data from the phase1/2 clinical study with its flagship candidate galinpepimut-S (GPS) in combination with pembrolizumab. GPS is the SELLAS’ Wilms Tumor-1 targeting peptide treatment.
The study conducted in collaboration with Merck
The company conducted the study under the Clinical Trial Collaboration and Supply Agreement with Merck & CO. The study evaluated GPS and pembrolizumab’s combination in treating second or third-line WT1 refractory or relapsed platinum-resistant advanced metastatic ovarian cancer patients. Interestingly, the WT1 antigen is among the commonly expressed cancer antigens in various malignancies. The National Cancer Institute has ranked it as a top priority in immunotherapy cancer antigens.
The study evaluated eleven patients that had received GPS doses combined with pembrolizumab for clinical responses, and three patients were evaluated to immune responses. Around 67% of the study patients had refractory or relapsed in second-line therapies, with 233.3% of the patients failing third-line therapy. However, the median overall survival is not known since all patients in the study are still alive as of the time of analysis.
GPS and pembrolizumab combination promising
Angelos Stergio, SELLAS CEO and President said, “Considering the overall poor prognosis in this particular clinical setting and based on the observed median PFS, overall survival and DCR in this study, combining GPS with the PD1 inhibitor pembrolizumab appears to be clinically promising as compared to bevacizumab-free salvage chemotherapy regimens and without the toxicity burden associated with the latter.”
Stergio explained that the patients who received GPS combined with pembrolizumab maintained a significant level of stable disease. The company will continue to review the data to determine the value of the combination in fighting the disease.