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, study of ALRN-6924 as a chemoprotection agent in patients with TP53-mutated HER2- breast cancer (stages IIa to IIIb) receiving neoadjuvant or adjuvant chemotherapy with doxorubicin, docetaxel, and cyclophosphamide (TAC). Chemotherapy affects cells that are dividing, whether they are tumor cells or healthy cells (including, bone marrow cells, hair follicle cells, and epithelial cells lining the gastrointestinal tract). ALRN-6924 is designed to stop cell division in healthy cells but not in tumor cells because they have a mutation of the TP53 gene. When this happens, tumor cells will still be destroyed by the chemotherapy but healthy cells that are not dividing may be spared from chemotherapy damage and the patient should have less side effects.

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.