OncoSec announced the first patient has been treated in KEYNOTE-890, a Phase 2 clinical trial for the treatment of late-stage triple negative breast cancer (TNBC) with TAVO (intratumoral plasma encoded IL-12, or tavokinogene telseplasmid, plus electroporation) in combination with Merck's Keytruda (pembrolizumab).

KEYNOTE-890 is designed as a multicenter Phase 2 open-label trial focusing on patients with a histologically confirmed diagnosis of inoperable locally advanced or metastatic TNBC and at least 1 prior line of approved systemic chemotherapy or immunotherapy. Twenty five patients are expected to be enrolled. Each patient will undergo 3-week treatment cycles with pembrolizumab administered as a 30-minute IV infusion day 1 of every cycle (flat dose of 200 mg) and treated with TAVO on days one, five and eight every six weeks.

"Treating the first patient in our KEYNOTE-890 clinical trial is an important milestone for OncoSec as we seek to rapidly advance this program," said Kellie Malloy Foerter, Chief Clinical Development Officer of OncoSec. "Additionally, this study is important for patients with metastatic triple negative breast cancer given the lack of treatment options currently available. Prior clinical observations suggest that TAVO in combination with pembrolizumab is a valid therapeutic approach for TNBC. Based on the outcome of the study and feedback from FDA, we may choose to expand the study and seek accelerated approval with the FDA for this patient population."

Breast cancer cells that test negative for estrogen receptors (ER-), progesterone receptors (PR-), and HER2 (HER2-) means the cancer is triple negative. Approximately 10-20 percent of U.S. breast cancer cases are triple negative breast cancer (TNBC), which disproportionately affects younger women, as well as African-American women, followed by Hispanic women.

TNBC remains a poor-prognosis breast cancer subtype, with limited treatment options for patients with advanced, recurrent disease. In the recurrent disease setting, chemotherapy remains the standard of care, and median survival is approximately 13 months from the time of disease recurrence. Emerging evidence shows immunotherapy options may play an important role in the treatment paradigm for TNBC. Preliminary data from early-phase studies demonstrated the anti-PD-1 antibody pembrolizumab led to an objective response in 18 to 19 percent of TNBC patients; and median overall survival was 8.9 months in a pretreated cohort. The anti-PD-L1 antibody atezolizumab (MPDL3280A) achieved an objective response in 25 percent of patients in the first-line and 11 percent of patients in the second-line setting. There is increasing evidence that tumors need TILs for anti-PD-1/PD-L1 therapies to be most effective. Data also show TILs promote better responses to chemotherapy and improve clinical outcomes in breast cancer, including TNBC.