A Study of ALRN-6924 for Protection of Chemotherapy-Induced Side Effects in Patients With TP53-Mutant Breast Cancer

This is a Phase 1b, open-label, single-arm, multicenter clinical trial for evaluation of safety, tolerability and chemoprotection effects of ALRN-6924 combined with chemotherapy in patients with TP53-mutated, HER2 negative breast cancer without distant organ metastases. All patients will receive the neoadjuvant or adjuvant chemotherapy regimen known as TAC. TAC consists of doxorubicin 50 mg/m2 IV infusion, docetaxel 75mg/m2 IV infusion and cyclophosphamide 500 mg/m2 IV infusion, given on Day 1 of every 3-week cycle for a total of 4-6 treatment cycles according to each patient's individual needs, individual institutional policies and standards of care, as well as investigator discretion. ALRN-6924 1.2 mg/kg will be administered on 3 consecutive days in each treatment cycle, Days 0-2. Prophylactic administration of G-CSF prior to the first instance of Grade 4 neutropenia is not allowed in Cycle 1. Myeloid growth factor support with filgrastim should be administered immediately if a patient is diagnosed with Grade 4 neutropenia.