EAGAN, Minn., Dec. 11, 2019 (GLOBE NEWSWIRE) -- Biothera Pharmaceuticals, Inc. announced today that updated response and clinical benefit data from its ongoing Phase 2 study in chemo-refractory metastatic triple negative breast cancer (mTNBC) patients were presented during a Spotlight Session at the 2019 San Antonio Breast Cancer Symposium (SABCS).

The study is evaluating Biothera’s Imprime PGG, a systemically delivered dectin receptor agonist that triggers anti-cancer immune responses, in combination with Merck’s anti-PD-1 therapy, KEYTRUDA^® (pembrolizumab).  Study participants had not been previously treated with immune checkpoint inhibitors and were identified as biomarker positive for Imprime PGG therapy.

“The maturing clinical data show compelling evidence for the clinical benefit from the combination of Imprime PGG and KEYTRUDA in chemo-refractory metastatic TNBC patients,” said Jeremy Graff, Ph.D., President and Chief Scientific Officer, Biothera Pharmaceuticals.  “Importantly, the translational data not only provide proof of concept at the molecular and cellular level, but also provide incredibly valuable insight that informs the next steps for Imprime PGG’s clinical development.”

Latest Data from IMPRIME 1 in mTNBC
IMPRIME 1 data presented at SABCS (as of November 11, 2019) showed an Overall Response Rate of 15.9% (n=7/44) among all mTNBC patients treated with the combination of Imprime PGG and KEYTRUDA, with one confirmed complete response (CR) (2.3%, n=1/44) and confirmed partial responses in six additional patients (13.6%, n=6/44).  An additional 38.6% (n=17/44) of patients had stable disease (SD) as best response.  The disease control rate (CR + PR + SD > 24 weeks) was 25% (11/44 patients).  Median Overall Survival (OS) is currently 16.4 months by Kaplan-Meier estimation with a median time to follow-up of 19.1 months.  The 12-month OS rate is 57.6%. Patients continue to be monitored for survival.

A majority of patients (62.5%) showed target lesion reduction or stabilization.  Treatment discontinuation often resulted from new lesions or non-target lesion increases, even while target lesions were shrinking or stable (22/41, 53.7%).  Patients with this mixed response pattern showed increased overall survival.

At baseline, patients were largely devoid of activated T cells.  Analyses of peripheral blood showed activated CD8 T cells as early as three weeks on therapy.  Tumor biopsies showed profound infiltration of activated myeloid and T cells into tumor tissue after six weeks of therapy.  These immune pharmacodynamic changes correlated with significantly greater OS.

“Patient response patterns and clinical benefit revealed extended OS even in those patients not classified as responders by RECIST criteria,” said Dr. Graff.  “The extended OS was most evident in patients with any reduction in target tumor burden.”

The Biothera Pharmaceuticals poster presentation at SABCS is number PD1-02, “Response and clinical benefit assessment of the combination of the dectin-1 agonist imprime PGG and anti-PD-1 pembrolizumab in chemotherapy-resistant metastatic triple negative breast cancer (TNBC).”

About Biothera Pharmaceuticals, Inc.
Biothera Pharmaceuticals is a privately held biotechnology company developing Imprime PGG, a novel dectin receptor agonist that reverses tumor-mediated immunosuppression while promoting antigen presentation to drive T cell activation and infiltration into tumors and to enhance clinical benefit from immune checkpoint inhibitors.  Biothera Pharmaceuticals is currently developing this platform drug through clinical research collaborations with Merck, Genentech, Dana Farber Cancer Institute and the Big Ten Cancer Research Consortium in cancers that include triple negative breast cancer, advanced melanoma, colorectal cancer and non-small lung cell cancer.

Contact:
Jeremy Graff, Ph.D.
President and Chief Scientific Officer
Biothera Pharmaceuticals, Inc.
651-675-0300
jgraff@biothera.com