Oncternal Therapeutics launches Phase 1b trial of Cirmtuzumab in combination with Paclitaxel in breast cancer

Oncternal Therapeutics, a leading U.S. oncology company, has announced the dosing of the first patient in a phase 1b trial of its investigational drug cirmtuzumab, used in combination with the standard-of-care chemotherapy drug paclitaxel. This trial marks a significant step in evaluating the potential of cirmtuzumab for treating patients with advanced stages of breast cancer.

The trial is being conducted in collaboration with the University of California San Diego (UC San Diego) School of Medicine. It targets breast cancer patients who are HER2/neu negative and have either metastatic or locally advanced unresectable cancer. The phase 1b trial aims to enroll up to 15 patients, who will undergo treatment protocols involving intravenous infusions of cirmtuzumab biweekly for the first two doses and then once every 28 days. Concurrently, patients will receive weekly doses of paclitaxel for up to six 28-day cycles.

The primary goals of this trial are to assess the safety, tolerability, time to progression, objective response rate, and ROR1 expression and activity measures. ROR1, a cell-surface receptor, has been identified as a critical marker in the progression and metastasis of several cancers, including breast cancer.

James Breitmeyer, President and CEO of Oncternal, provided insights into the trial’s foundation, “Expression of ROR1 on primary breast cancers has been associated with a higher risk of relapse over time, and is correlated with markers of EMT (epithelial-mesenchymal transition). Treatment of breast cancer cells in the laboratory with cirmtuzumab, which binds with high affinity to ROR1, inhibits tumor growth and metastasis.”

Breitmeyer further highlighted encouraging results from preclinical studies, stating, “In further preclinical studies, our collaborators showed that no tumors formed when cells harvested from breast cancer tumors treated with cirmtuzumab and paclitaxel were implanted into new animals. These data validate the rationale for combining cirmtuzumab with paclitaxel.”

Besides breast cancer, cirmtuzumab is also under investigation as a potential therapy for chronic lymphocytic leukemia and mantle cell lymphoma. A phase 1b/2 trial combining cirmtuzumab with ibrutinib in treating B-cell malignancies was initiated by Oncternal in May 2018, reflecting the broad applicability of this investigational therapy across different cancer types.

The initiation of this phase 1b trial by Oncternal Therapeutics represents an essential step in exploring advanced therapeutic options for breast cancer, with the potential to significantly impact patient outcomes and expand treatment paradigms in oncology.