This study will evaluate the safety and tolerability of PMD-026 using an accelerated titration design to define the MTD in metastatic breast cancer, followed by an expansion at the RP2D in triple negative breast cancer. All patients will receive daily oral doses of PMD-026 until either disease progression or unacceptable toxicity. Patients will have disease assessments initially after 6 weeks of treatment, and every 9 weeks thereafter.~Patients enrolled to the Dose Escalation Phase must have histologically or cytologically diagnosed metastatic breast cancer that has progressed on or after standard of care therapy. Patients enrolled to the Dose Expansion Phase must have histologically or cytologically diagnosed metastatic triple negative breast cancer from initial diagnosis (ER/PgR <1%, HER2 negative) that has progressed on or after standard of care therapy. All patients must provide tumor tissue (archival preferred) prior to study entry.~A subset (N=12) of patients in Part 2 of the study will participate in a 1- week evaluation of the effect of food on PMD-026 oral absorption.~PMD-026 is an oral, reversible small molecule inhibitor of RSK1-4 with high selectivity for RSK2. High levels of RSK2 expression have been associated with worse overall survival in breast cancer. Inhibiting RSK2 may inhibit growth of breast cancer.
The purpose of this study is to test the safety and tolerability of PMD-026 in patients with metastatic breast cancer and triple negative breast cancer. PMD-026 is a targeted oral agent designed to kill tumor cells in metastatic breast cancer and triple negative breast cancer.