PHILADELPHIA--(BUSINESS WIRE)--Context Therapeutics, a clinical stage biopharmaceutical company dedicated to the treatment of hormone driven cancers, today announces it has signed multiple research collaborations to further understand the role of progesterone receptor (PR) signaling and its blockade to overcome resistance mechanisms underlying metastatic breast cancer (mBCa). These collaborations are with key leaders in the progesterone and breast cancer fields and include Dr. Carol Lange, PhD at University of Minnesota and Dr. Suzanne Fuqua, PhD at Baylor College of Medicine, both of whom also serve as Scientific Advisory Board members at Context. Additional academic collaborations include the laboratories of Dr. Sarat Chandarlapaty, MD, PhD at Memorial Sloan Kettering Cancer Center, Dr. Geoffrey Greene, PhD at University of Chicago and Dr. Seema Khan, MD at Northwestern University.

Breast cancer is the most commonly diagnosed cancer and the second leading cause of cancer related death in women. Approximately 155,000²women in the United States have mBCa and the median overall survival in this setting is three years³. Three primary mBCa subtypes exist: hormone receptor positive (HR+) that express estrogen receptor (ER) and/or progesterone receptor (70-80% of patients)⁴; human epidermal growth factor receptor 2 (HER2)-positive (10-15%)⁵; and triple negative (10-17%)⁶. For patients with HR+ mBCa, antiestrogen blockade is the backbone therapy across first (1L) and second (2L) treatment lines. Unfortunately, current treatments in 1L and 2L are not curative and only delay progression to chemotherapy. Therefore, there is a critical need for targeting additional mechanisms alone or in combination with antiestrogens to enhance therapeutic response and provide these patients with better outcomes.

Progesterone, a major mitogen in the adult human mammary epithelium, is also a key driver of breast cancer cell proliferation. Context Therapeutics is pursuing an innovative approach to the treatment of advanced breast cancer by blocking both ER and PR, the primary drivers of HR+ mBCa disease progression, through the combination of Apristor, a unique PR full antagonist⁷, with the antiestrogen Falsodex^®8 (fulvestrant). Apristor has established efficacy as an antitumor agent in the clinical setting, as well as in multiple preclinical breast cancer models and exhibits additive/synergistic effects with antiestrogens, providing a strong rationale for this combination.

A Phase 2 clinical trial in advanced breast cancer patients with Apristor in combination with Fulvestrant in 2L therapy is planned for early 2019. The randomized, double-blind, placebo-controlled study will be powered to show efficacy with Apristor added to the standard of care (Fulvestrant) versus the standard of care alone.

The research at the above academic centers will focus on expanding the understanding of mechanisms underlying resistance in breast cancer and novel therapeutic combinations that could be useful in treating advanced breast cancer with Apristor.

Under the terms of the collaborations, Context will provide Apristor and collaborate with the research groups. While it is well known that Apristor is a unique PR antagonist that inhibits both ligand-dependent and growth factor induced PR activities, access to the drug for basic research purposes has been historically limited. Context is providing the compound to key interested academic partners with the aim of advancing breast cancer research and understanding the role of PR signaling in mammary tumors and other indications.

About Progesterone Receptor Antagonism

Context is developing Apristor, a first-in-class orally-bioavailable progesterone receptor (PR) antagonist for PR+ breast cancer. Up to 60% of breast cancer patients are believed to be PR+⁹. Apristor is an investigational medicine that has completed Phase 1 development and will be further evaluated in an upcoming randomized, placebo-controlled Phase 2 trial in second-line metastatic breast cancer patients who are PR+ and have failed prior antiestrogen therapeutic with or without the addition of a Cdk4/6 inhibitor.

¹ When discussing historical trials, references to Apristor include both onapristone immediate release and onapristone extended release; all current and future trials will consist solely of onapristone extended release.

² Cancer Epidemiol Biomarkers Prev. 2017 26(6): 809–815

³ Breast. 2012; Vol 21, Issue 3, pages 242–252

^4,5,6 American Cancer Society. Breast Cancer Facts & Figures 2017-2018. Atlanta: American Cancer Society, Inc. 2017

⁷ Steroid Biochem. Molec. Biol. Vol. 53, No. 1-6, pp. 449-458, 1995; Journal of Hematology & Oncology (2017) 10:89; Molecular Cellular Biology, Mar. 1998, p. 1369–1378; Oncogene (2014), 1–10

⁸ Falsodex^® is a registered trademark of the Astra Zeneca group of companies

⁹ www.breastcancer.org