Context Therapeutics Announces New Preclinical Data on Apristor at San Antonio Breast Cancer Symposium

Apristor® Shows Synergistic Activity in Combination with a SERD or Cdk4/6 Inhibitor in Preclinical Models of Breast Cancer

Supports Planned Phase 2 Clinical Trial of Apristor plus Faslodex®

Philadelphia, PA, December 8, 2018 – Context Therapeutics, a clinical-stage biotechnology company, today announced new preclinical data on Apristor® (onapristone extended release), its first-in-class full progesterone receptor (PR) antagonist, showing that the investigational medicine inhibits tumor cell line growth in hormone receptor positive (HR+) breast cancer cell lines. Additionally, it was shown that Apristor is additive with current standard of care therapies for HR+ metastatic breast cancer, including the Cdk4/6 inhibitor Ibrance® (palbociclib) and the selective estrogen receptor degrader Faslodex® (fulvestrant).

“Progesterone receptors are under appreciated as potent stimulators of breast cancer growth”, said Carol Lange, PhD, Professor of Medicine at the University of Minnesota and principal investigator of the research presentation. “HR+ breast cancer is driven by two hormones, estrogen and progesteroneand the PRs have not been fully leveraged as important estrogen receptor (ER) partners in the treatment of breast cancer. While there are over half a dozen approved medicines to block ER and estrogen-related signaling, there are no FDA approved medicines in cancer that block PR. The data presented shows blocking progesterone-related signaling via Apristor is not only active alone in tumor models but it also enhances the activity of medicines that either directly or indirectly target estrogen-driven pathways.”

The data presented shows that:

  • The progesterone receptor pathway is a unique target,distinct from the estrogen receptor pathway 

  • PR in addition to ER is critical for in vitro growth and survival of HR+ breast cancer cells

  • PR antagonism via Apristor reduces the expression of cancer promoting genes

  • PR antagonism enhances the inhibitory effects of Cdk4/6 inhibitors and Fulvestrant on HR+ breast cancer cells

“We are encouraged by these new preclinical data, which speak to the important role PR plays in facilitating HR+ breast cancer disease progression,” said Deepak Lala, PhD, Chief Technology Officer of Context. “This is the first study to show that PR antagonism provides greater inhibition of breast cancer cell proliferation and survival when combined with new treatment modalities, including Cdk4/6 inhibition.”

About Apristor

Apristor® (onapristone extended release) is Context’s wholly owned, first-in-class, orally active extended release formulation of onapristone, a full progesterone receptor antagonist.  Progesterone receptor [PR] plays a critical role in facilitating breast cancer disease progression as well as therapeutic resistance to first line antiestrogen and/or Cdk4/6 inhibitor therapies. Apristor is the only full PR antagonist that is being developed to target breast cancer. Apristor has the potential to transform the treatment of breast cancer, through the potent inhibition of PR signaling thereby blocking breast cancer cell proliferation and overcoming resistance to first line antiestrogen and Cdk4/6 inhibitor therapy.

About Context Therapeutics

Context Therapeutics is a clinical-stage biopharmaceutical company dedicated to creating new medicines to treat hormone-responsive cancers. Context’s lead program is Apristor® (onapristone extended release), an investigational Phase 2 drug that is being developed for progesterone receptor positive (PR+) cancers. In addition, Context is advancing CTX-30916, a preclinical progesterone receptor antagonist, and a discovery-stage program targeting Sigma1. For more information on Context, visit


Context Contact

Context Therapeutics
Deepak Lala, PhD
Chief Technology Officer


Investor Contact

Solebury Trout
Michael Levitan

Faslodex® is a registered trademark of AstraZeneca

Ibrance® is a registered trademark of Pfizer Inc.

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