A Study of Bosmolisib (BR101801) in Participants With R/R PTCL.

Key Inclusion Criteria: 1. The ECOG performance status ≤ 2. 2. Life expectancy more than 3 months. 3. Patients with relapsed and/or refractory to standard therapy or are intolerance to standard therapy diagnosed with 2022 World Health Organization (WHO) classification * Peripheral T-cell lymphoma, not otherwise specified * Nodal TFH cell lymphoma, angioimmunoblastic-type * Nodal TFH cell lymphoma, follicular-type * Nodal TFH cell lymphoma, NOS 4. Patients currently requiring systemic therapy at the investigator's discretion. 5. Patients with a lesion measuring 1.5 cm or more in its longest transverse diameter, as determined by CT, PET/CT or MRI scans according to the 2014 Lugano criteria. Key Exclusion Criteria: 1. The presence of overt leptomeningeal or active central nervous system (CNS) metastases, or CNS metastases that require local CNS-directed therapy or increasing doses of corticosteroids within the prior 2 weeks. 2. Impaired cardiac function or clinically significant cardiac disease. 3. Patients with interstitial pneumonia or history of drug-induced interstitial pneumonia/pneumonitis. 4. For patients with lymphoma: * Systemic antineoplastic therapy (including cytotoxic chemotherapy, alfa-interferon \[INF\], and toxin immunoconjugates) or any experimental therapy within 3 weeks or 5 half lives, whichever is shorter, before the first dose of study treatment. * Therapy with tyrosine kinase inhibitor within 5 half-lives before the first dose of study treatment. * Unconjugated monoclonal antibody therapies \< 6 weeks before the first dose of study treatment. 5. Patients receiving systemic chronic steroid therapy or any immunosuppressive therapy (\>20 mg/day prednisone or equivalent).