OncoSec Medical Incorporated announced early clinical data from an investigator-sponsored trial (IST) conducted by Dr. Ahmad Tarhini at the H. Lee Moffit Cancer Center & Research Institute. This IST is evaluating TAVO™, OncoSec's proprietary interleukin 12 (IL-12) encoding plasmid delivered by intratumoral electroporation (TAVO™-EP), in combination with intravenous nivolumab. The trial enrolled patients with high-risk operable locoregional advanced stage IIIB-D or stage IVA melanoma.

By the time of data cutoff, 10 of 12 patients had completed the neoadjuvant phase of up to three 4-week cycles of TAVO™-EP on days 1 and 8 (with an optional third treatment on day 15) concurrently with 480 mg nivolumab administered every 4 weeks. Following the neoadjuvant treatment period, surgery was performed and adjuvant nivolumab was continued for up to 1 year. A preoperative overall response rate (ORR) by RECIST v1.1 was observed in 7 of 10 patients (70%) consisting of 4 patients with complete response (CR) and 3 patients with partial response (PR).

Two patients had stable disease (SD) and 1 patient showed progressive disease (PD). One patient with a RECIST v1.1 PR declined surgery due to significant response after neoadjuvant treatment. At time of surgery, 8 of 9 (88.9%) evaluated patients had a major pathologic response (pMR; =10% viable tumor cells in the analyzed surgical specimen), 6 of 9 patients (66.7%) had a pathological CR (pCR).

No disease recurrence has been observed at a median follow up of 7 months from the date of surgery. Tumor-relevant immune biomarkers, analyzed pre-treatment for 6 patients, included CD8+ tumor infiltrating lymphocytes (TILs), PD-L1 expression levels and tumor inflammation signature (TIS) in the tumor lesions. This analysis identified four patients with low CD8+ TIL, low PD-L1 and low TIS; a biomarker signature that is negative predictive for response to immunotherapy.

Of note, all four of these patients achieved pCR. Among the 12 patients with safety data, there were no grade 4/5 treatment-related adverse events; 1 patient experienced a grade 3 event of hyponatremia. Overall, the combination treatment was well tolerated, and no patient discontinued neoadjuvant treatment due to toxicity.

Patients continue to enroll.