Patient Enrollment Expands in Trial Evaluating Novel Drug in Breast Cancer

Enrollment is underway in a phase 2 clinical trial evaluating the novel drug OP-1250, a complete estrogen receptor (ER) antagonist (CREAN) and a selective ER degrader, in patients with ER-positive, HER2-negative metastatic breast cancer.

“We are excited about the potential of OP-1250 and are expeditiously advancing the development program as we work to further position OP-1250 as a differentiated CERAN and potential endocrine therapy of choice for ER-positive breast cancer,” said Dr. Naseem Zojwalla, chief medical officer of Olema Oncology, the drug’s manufacturer, in a press release. “Enrollment is underway in phase 2 monotherapy, and we look forward to further evaluating OP-1250’s benefit in treating ER-positive, HER2-negative breast cancer patients.”

The decision to advance the therapy at a 120 milligram (mg) dosage to a phase 2 trial comes based off safety, tolerability and encouraging results from a previous phase 1b trial. That trial compared two doses of the therapy in 50 patients (60 mg versus 120 mg).

The phase1b trial demonstrated encouraging early anti-tumor activity with four patients achieving a partial response (a decrease in tumor size or the amount of cancer in the body as a response to treatment) in 31 evaluable patients.

Most of the patient-reported side effects in the early-phase trial were moderate and included nausea, vomiting, fatigue and headache. Three patients experienced severe or worse neutropenia (what a person has too few neutrophils, which are a type of white blood cell).

The phase 2 enrollment will continue and include three groups of patients: 50 with measurable disease, 15 with non-measurable disease and 15 with CNS metastasis (disease that has spread from its primary site to the central nervous system).

In total, the expected patient enrollment across the phase 1 and phase 2 portion of the trial is 94 patients.

Patients enrolled onto the trial are not allowed to have received oral endocrine therapy more than two weeks prior to receiving their first dose of OP-1250. Moreover, patients cannot have received Faslodex (fulvestrant); or any chemotherapy, antibody therapy or investigational therapy within four weeks of receiving their first treatment with OP-1250.

Patients with ER-positive, HER2-negative metastatic breast cancer must also have an adequate liver and kidney function to be enrolled onto the trial.

Patients who present with gastrointestinal disease, significant kidney disease or cardiovascular disease will be excluded from the trial.

This study is expected to be complete by December 2023 and the manufacturer noted in the release that it plans to launch another trial assessing single-agent OP-1250 next year.

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