Tiragolumab, Atezolizumab and Chemotherapy in Triple Negative Breast Cancer

This is a phase II study, preceded by a safety run-in, with two independent cohorts (cohort A in early Triple Negative Breast Cancer (TNBC) patients and cohort B in late in metastatic TNBC patients) designed to evaluate the efficacy of atezolizumab, tiragolumab and chemotherapy.

In the early TNBC setting (cohort A) dedicated to patients with newly diagnosed, previously untreated, non-metastatic disease (tumor stage T1c, nodal stage N1-2, or tumor stage T2-4, nodal stage N0-2), the treatment will consist in: First part: Nab-paclitaxel administered weekly in combination with atezolizumab, tiragolumab and carboplatin, administered every 3 weeks over 12 weeks Second part: Atezolizumab, tiragolumab, doxorubicin and cyclophosphamide, administered every 3 weeks over 12 weeks Patients will undergo surgery of the primary disease 3 to 6 weeks after last neoadjuvant treatment dose, followed by 9 cycles of atezolizumab and tiragolumab administered every 3 weeks. Treatment efficacy will be assessed early on, through 18F-FDG PET/CT during the first two cycles. Patients whose tumor shows no sign of response after two cycles (i.e. no partial or complete metabolic response of the breast tumor according to 18F-FDG PET/CT by PERCIST criteria) would then be switched to standard treatment, per investigator decision. Tiragolumab 600 mg and Atezolizumab 1200 mg administered by IV infusion every 3 weeks after surgery for a total of 9 cycles. In the metastatic TNBC setting (cohort B) dedicated to patients with locally recurrent inoperable or metastatic disease eligible to first line treatment, patients will be included regardless of their PD-L1 tumor expression defined by immunohistochemistry (Ventana SP142) at baseline, but no more than 40% of PD-L1 negative (i.e \<1%) will be included. The treatment will consist in nab-paclitaxel administered at d1, d8, d15 of every 28-day cycle, combined with atezolizumab and tiragolumab administered every 3 weeks until disease progression or limiting toxicity. Treatments will be administered until disease progression or limiting toxicity. As the the combination Atezolizumab + Tiragolumab + chemotherapy has never been tested, a safety run-in phase of 10 patients is planned in each cohort to verify the tolerance of the combination