On June 9, 2020 OncoSec Medical Incorporated (NASDAQ:ONCS) (the "Company" or "OncoSec"), a company developing late-stage intratumoral cancer immunotherapies, reported that, based upon tumor regression and associated clinical responses observed in the heavily pretreated Cohort 1 of the KEYNOTE-890 study, the Company plans to expand into earlier first-line treatment to investigate the combination of OncoSec’s lead product candidate TAVO (plasmid-based interleukin-12 or pIL-12) and Merck’s KEYTRUDA (pembrolizumab) plus chemotherapy in patients with inoperable locally advanced or metastatic triple negative breast cancer (mTNBC) (Press release, OncoSec Medical, JUN 9, 2020, View Source [SID1234560939]). Cohort 2 will be added as a second arm to the ongoing KEYNOTE-890 study.

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Merck’s Phase 3 KEYNOTE-355 trial evaluating KEYTRUDA in combination with chemotherapy in first-line mTNBC recently reported a statistically significant and clinically meaningful improvement in progression free survival (PFS) with the combination of KEYTRUDA plus chemotherapy versus chemotherapy alone for first-line treatment of patients with PD-L1 positive (CPS ≥10) mTNBC. Safety was consistent with known profiles of each regimen. These findings, as well as the strong signal, even in patients with PD-L1 negative tumors, and excellent safety profile observed in KEYNOTE-890 Cohort 1, served as the basis for OncoSec’s decision to move into first-line mTNBC.

Specifically, Cohort 2 of the KEYNOTE-890 study will evaluate the addition of TAVO in combination with KEYTRUDA and chemotherapy in the first-line setting in approximately 40 patients with mTNBC. The primary endpoint will be overall responder rate (ORR) by blinded independent central review (BICR) based on RECIST v1.1. Should positive results from the KEYNOTE 890 Cohort 2 be observed, the Company plans to expand it and utilize the results from the expansion to seek accelerated approval.

In December 2019, OncoSec presented interim data of 28.6% ORR from Cohort 1 at the San Antonio Breast Cancer Symposium. These data included four confirmed partial responses, as assessed by the investigator, in 14 patients who were refractory to chemotherapy and had progressed after an average of three prior lines of therapy. Three of the four responding patients’ lesions were PD-L1 negative by IHC analysis before treatment (the fourth patient was undetermined). Importantly, TAVO and pembrolizumab were well tolerated.

"TAVO and KEYTRUDA have already demonstrated strong clinical data in heavily pretreated metastatic TNBC patients and we, along with our partners at Merck, recognize a compelling opportunity to improve response rates in a much larger overall patient population by moving into first-line metastatic TNBC where there remains a high unmet medical need," said Daniel J. O’Connor, President and Chief Executive Officer at OncoSec. "We are optimistic about the potential for TAVO to improve progression free survival and overall survival for metastatic TNBC patients. We expect to begin enrollment in KEYNOTE-890 Cohort 2 next quarter and, if successful, intend to expand Cohort 2 into a registration directed study."

For more information about the KEYNOTE-890 study, click here.

About Triple Negative Breast Cancer (TNBC)

TNBC is an aggressive type of breast cancer that characteristically has a high recurrence rate within the first five years after diagnosis. While some breast cancers may test positive for estrogen receptor, progesterone receptor, or human epidermal growth factor receptor 2 (HER2), TNBC tests negative for all three. As a result, TNBC does not respond to therapies targeting these markers, making it more difficult to treat. Approximately 10-20% of patients with breast cancer are diagnosed with TNBC.