OncoSec Medical Incorporated announced interim results from KEYNOTE-890, an ongoing Phase 2 study of TAVO™ (intratumoral IL-12) in combination with KEYTRUDA® (pembrolizumab), an anti-PD-1 checkpoint inhibitor, in patients with metastatic, chemotherapy-refractory triple negative breast cancer (mTNBC). Patients who previously had progressed after an average of three prior lines of chemotherapy were enrolled in the KEYNOTE-890 study to evaluate if the addition of TAVO could provide meaningful clinical activity when combined with KEYTRUDA®. The interim analysis, presented on December 12, 2019, at the San Antonio Breast Cancer Symposium, included more than half of the patients (14 out of 25) enrolled in the KEYNOTE-890 study evaluating tumor responses, related immunological responses and safety. Four of the 14 patients showed a rapid tumor reduction and had a confirmed partial response by RECIST v1.1 (ORR 28.5%), including a deep partial response in a patient with multiple liver, bone, skin and nodal metastases and a short disease-free interval following neoadjuvant chemotherapy. All responses are ongoing (range: 6 to 9 months) and a median duration of response (DOR) has not yet been reached. Three of the four patients with a partial response experienced deepening tumor shrinkage over six months. These interim findings compare favorably to the response rate (range of 6-10%) observed with KEYTRUDA as a monotherapy in mTNBC patients. Importantly, TAVO and pembrolizumab were well tolerated, with only 3 of 16 patients experiencing grade 3 treatment-related adverse events with combination treatment. Patients demonstrated encouraging immunological responses in tumor and blood consistent with an IL-12-associated mechanism of action, including significantly increased on-treatment proliferating T cell subsets in the periphery and increased gene expression signatures associated with productive immunological responses in the tumor. Biomarker analysis of patient tumor and blood samples are ongoing. To date, the KEYNOTE-890 study has enrolled 24 of the planned 25 patients. OncoSec expects to report the full data results in 2020.