Pilot Clinical Trial of Treatment With LY3023414 and Prexasertib to Inhibit Homologous Recombination (HR) in Patients With Chemotherapy-Pretreated Metastatic Triple Negative Breast Cancer (Amendment 1)

Metastatic TNBC patients will consent to and undergo core needle biopsies of a metastatic lesion for NGS, RPPA, and other molecular analyses at study entry. Patients will then be treated with 150 mg LY3023414 PO BID and prexasertib 80 mg/m\^2 IV administered every 2 weeks until disease progression or unacceptable toxicity. Any time after the completion of Cycle 2 of the treatment combination, or at the physician's discretion, a second core needle biopsy of the same metastatic lesion (or different metastases if the initial metastasis has regressed) will be performed for RPPA and other molecular analyses. If a research biopsy from a patient's metastatic disease cannot be safely obtained, a skin biopsy is permitted. Treatment will be discontinued in patients who achieve a confirmed clinical complete response, and these patients will be followed to document the durability of the complete responses.