A Study Evaluating the Safety and Efficacy of BEAM-201 in Relapsed/Refractory T-Cell Acute Lymphoblastic Leukemia (T-ALL) or T-Cell Lymphoblastic Lymphoma (T-LL)

Key Inclusion Criteria:

• Ages 18 to ≤ 50 years.
• Ages ≥ 1 year to < 18 years, after health authority approval.
• T-ALL/T-LL that is CD7-positive (defined as at least 20% of blasts positive for CD7 by flow cytometry or immunohistochemistry based on assessment of the study site's CLIA [Clinical Laboratory Improvement Amendments of 1988] certified facility) in second or greater relapse, first relapse post-transplant relapse, or chemotherapy-refractory disease. Specifically:

• Second or greater relapse or post-transplant relapse, defined as:

• BM with ≥ 5% lymphoblasts by morphologic assessment or evidence of extramedullary disease at screening after second documented CR; OR
• Flow cytometric confirmation of relapsed T-ALL of at least 0.1% after second CR documented to have been MRD negative < 0.1%; OR
• Any detectable relapsed disease post-allogeneic HSCT with flow cytometric confirmation of T-ALL of at least 0.1%; OR
• Biopsy confirmed evidence of relapsed T-LL on lymph node biopsy after second CR; OR
• Any detectable disease post-allogeneic transplant with biopsy confirmed evidence of T-LL on lymph node biopsy
• Refractory disease, defined as:

• Primary refractory T-ALL or T-LL, defined as failure to achieve CR after induction chemotherapy, per investigator assessment and based on biopsy-confirmed evidence of residual T-ALL or T-LL; OR
• Relapsed, refractory disease, defined as > 5% BM blasts or biopsy-confirmed evidence of residual TLL after 1 course of re-induction chemotherapy for patients who have relapsed after previously achieving a CR NOTE: Patients with mixed phenotype acute leukemia with T-cell dominant phenotype may be enrolled if the aforementioned criteria are met.
• Eligible for myeloablative conditioning for and allogeneic HSCT based on the investigator's assessment with an available donor identified by a FACT accredited transplant center.

Key Exclusion Criteria:

• CNS involvement meeting any of the following criteria: CNS-3 disease, progressive CNS involvement despite therapy, CNS parenchymal or cranial nerve lesions on imaging.
• Clinically active CNS dysfunction or known history of irreversible neurological toxicity related to prior antileukemic therapy.
• Receipt of prior CD7 targeted therapy.
• Systemic antileukemic therapy intended to induce or maintain remission within 14 days prior to completion of screening.