A CDx for onapristone

Arno Therapeutics Selects Leica Biosystems to develop companion diagnostic for targeted oncology therapy

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FLEMINGTON, N.J.—Arno Therapeutics Inc., a clinical-stage biopharmaceutical company focused on the development of oncology therapeutics, and Leica Biosystems, a global leader in pathology workflow solutions and automation, announced in early January that the companies have entered into a co-development agreement to produce a companion diagnostic (CDx) for Arno’s lead compound and personalized therapy, onapristone.
Onapristone is an oral, anti-progestin hormone blocker that has been shown to have antitumor activity in breast cancer, and Arno notes that onapristone appears to selectively block the activation of the progesterone receptor (APR). This is believed to inhibit the growth of APR-driven breast, endometrial and other tumors.
The companion diagnostic will be an immunohistochemical (IHC) in-vitro diagnostic test used to detect APR in various women’s cancers, including endometrioid and breast cancer. This CDx test will help to identify patients who are APR positive and therefore most likely to respond to treatment with onapristone.
According to the company, there may also be an application for this companion diagnostic in the treatment of castration-resistant prostate cancer (CRPC). In preclinical work sponsored by Arno, IHC testing on archived specimens has shown that approximately 40 percent of archived endometrioid cancer specimens and approximately 25 percent of archived breast cancer specimens were APR positive. Initial findings by Arno indicate that the progesterone receptor was present in CRPC specimens and potentially active in a subset of tumors. Further investigation is underway to determine the frequency of APR-positive tumors in CRPC specimens.
“This agreement with Leica Biosystems is a significant milestone for Arno and an important step forward in the development of onapristone,” said Glenn Mattes, CEO of Arno Therapeutics. “We believe that partnering with a world-class organization such as Leica will enable us to quickly and effectively get to reliable, reproducible and practical APR-positive tumor detection. This will help identify the patients most likely to benefit from treatment with onapristone. We are excited about what the future holds for Arno as we enter a critical period for the company with the commencement of our first Phase 1 trial, which will evaluate onapristone in progesterone receptor-positive tumors.”
Under the terms of the co-development agreement, Arno will sponsor and conduct clinical trials for onapristone. Leica will develop and validate the CDx for APR with responsibility for ensuring the investigational CDx kit is ready, available and meets U.S. Food and Drug Administration and other health authority standards for a planned Phase 2 trial of onapristone in endometrioid cancer. The co-development program aims to achieve simultaneous approval and launch of onapristone and the in-vitro CDx for APR.
 “We are pleased to partner with Arno to co-develop this companion diagnostic for onapristone,” said Dr. Matthias Weber, president of Leica Biosystems. “Personalized medicine is a key development in oncology. We believe that diagnostics such as the APR test will play a critical role in the broader effort to improve quality of care for patients.”
Leica Biosystems is a global leader in pathology workflow solutions and automation, striving to advance cancer diagnostics to improve lives, and the company provides anatomical pathology laboratories and researchers a comprehensive product range for each step in the pathology process, from sample preparation and staining to imaging and reporting.
Arno Therapeutics is a clinical-stage biopharmaceutical company developing innovative products for the treatment of cancer, and it has exclusive worldwide rights to develop and market three innovative anticancer product candidates. These compounds are in clinical or preclinical development as product candidates to treat hematologic malignancies and solid tumors.
Arno enrolled the first patient in its Phase 1 dose escalation study evaluating onapristone in post-menopausal women with progesterone receptor-positive tumors on Jan. 21.
According to Mattes, the enrollment of the first patient in the Phase 1 trial “is a tremendous milestone for Arno and is testament to the considerable strides we have made in the past year. We are focused on driving forward the development of onapristone in the most efficient and cost-effective manner and believe it could fill a unique position in the market as there is significant potential for it be the first approved anti-progestin in oncology. We are at the forefront of establishing a genuine appreciation for the role of the progesterone receptor in cancer and the activated form as a biomarker, and we look forward to successfully developing our program.”
“Through a clearly defined development pathway, our initial strategy is to target the activated form of progesterone receptor positive cancers in two indications with high unmet medical need: endometrioid cancer and castration-resistant prostate cancer,” noted Dr. Alex Zukiwski, chief medical officer of Arno Therapeutics. “Through preclinical work, we've established that a significant percentage of endometrioid cancer tumor specimens are APR positive. The goal of the Phase 1 study underway is to determine the recommended dose for onapristone that we can utilize for a Phase 2 trial of patients with recurrent or metastatic endometrioid cancer.”

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