Context Therapeutics and Memorial Sloan Kettering Cancer Center Announce a Phase 2 Basket Trial for Apristor in PR+ Gynecological Cancers

  • Apristor®, an oral progesterone receptor antagonist, is being studied in patients with gynecological cancers who are progesterone receptor positive (PR+)

  • Up to 84 PR+ patients will be enrolled across three groups: Low Grade Serous Ovarian Cancer (LGSOC), Granulosa Cell Tumor of the Ovary, Endometrioid Endometrial Cancer

(Philadelphia, PA), May 2, 2019:   Context Therapeutics, a clinical-stage biopharmaceutical company dedicated to advancing medicines for hormone driven cancers, today announced the start of an open-label (NCT03909152) basket study to evaluate the efficacy and safety of Apristor (onapristone extended release) in advanced gynecological tumors that are progesterone receptor positive (PR+). Rachel N. Grisham, MD of Memorial Sloan Kettering Cancer Center is the study’s Primary Investigator.

The Phase 2 trial will include patients who have different PR+ solid tumors in advanced stages, including low grade serous ovarian, granulosa cell, and endometrioid endometrial cancer, who have received prior chemotherapy treatment. The progesterone receptor antagonist Apristor will be assessed in up to 84 cancer patients. The primary endpoint will be overall response rate (ORR), which is the proportion of patients who have either a complete or partial response. To further characterize the activity of Apristor, secondary endpoints will include duration of response, clinical benefit rate, and progression-free survival (PFS). In addition, this study will evaluate the safety and pharmacological profile of Apristor in these patients, as well as biomarker analyses to explore predictive factors of response to Apristor. Preliminary trial results are expected in mid-2020.

“Currently, there are limited therapeutic options to treat these cancers in the advanced setting. Recent preclinical findings, together with Phase 1 study results in patients with advanced PR+ ovarian and endometrial cancers, give us reason to believe that Apristor can help these women with PR+ gynecological cancers,” said Tarek Sahmoud, MD, PhD, Chief Medical Officer of Context Therapeutics. [1],[2]. “We believe Apristor can make a meaningful difference for patients in the trial.” 

For more information about the trial being conducted, please visit:

About Apristor
Apristor (onapristone extended release) is an investigational new drug that is an orally administered full progesterone receptor antagonist. Currently, there are no approved therapies that selectively target PR+ cancers. In a recent Phase 1 trial, Apristor was well tolerated and exhibited clinical benefit in heavily pretreated patients with PgR+ endometrial, ovarian and breast cancer. Preclinical data suggest that Apristor has anticancer activity by blocking the activation of progesterone receptor signaling by progesterone and/or mitogenic growth factors, inhibiting mammosphere formation, and downregulating gene signatures associated with cancer stem cell mobilization and metastasis [3],[4].

About Context Therapeutics
Context Therapeutics is empowering people with cancer to take back their lives.

Context is a clinical-stage biopharmaceutical company advancing medicines to treat hormone driven cancers. Context’s lead program is Apristor, an investigational Phase 2 drug that is being developed for progesterone receptor positive (PR+) metastatic breast, ovarian, and endometrial cancers. In addition, Context is advancing CTX-30916, a preclinical progesterone receptor agonist, and a discovery-stage program targeting Sigma1.  For more information on Context, visit

Contact Information

Company Contact:
Martin Lehr
Co-Founder & Chief Executive Officer


Investor Contact:
Solebury Trout
Michael Levitan

[1] Huang, Y, et al. (2018) Inhibiting nuclear phospho-progesterone receptor enhances antitumor activity of onapristone in uterine cancer. Molecular cancer therapeutics17(2), 464-73. 

[2] Cottu PH, et al. (2018) Phase I study of onapristone, a type I antiprogestin, in female patients with previously treated recurrent or metastatic progesterone receptor-expressing cancers. PLoS ONE 13(10): e0204973.

[3] Knutson TP et al. (2017) Posttranslationally modified progesterone receptors direct ligand-specific expression of breast cancer stem cell-associated gene programs. Journal of Hematology & Oncology 10:89.

[4] Truong TH et al. (2019) Phosphorylated progesterone receptor isoforms mediate opposing stem cell and proliferative breast cancer cell fates. Endocrinology 160:430–46.

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