Can a burst of radiation make CAR t-cells fight cancer harder?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: For Diffuse Large B-Cell Lymphoma (DLBCL) Cohort: * Diagnosis of DLBCL that is refractory to first-line chemoimmunotherapy, relapses within 12 months of first-line chemoimmunotherapy, relapses after 12 months in a transplant-ineligible patient, or is relapsed/refractory after two or more lines of systemic therapy. Eligible histologies include DLBCL not otherwise specified, primary mediastinal large B-cell lymphoma, high-grade B-cell lymphoma, and DLBCL arising from indolent lymphoma (follicular lymphoma, marginal zone lymphoma, or chronic lymphocytic leukemia) * Age ≥18 years * ECOG performance status ≤2 * Measurable disease on PET/CT or CT per Lugano Criteria * Adequate organ function: ANC ≥1000 cells/mm³; platelet count ≥75,000 cells/mm³; creatinine clearance or eGFR ≥45 mL/min; total bilirubin ≤2.0x ULN; AST or ALT ≤3.0x ULN; left ventricular ejection fraction \>40% For Multiple Myeloma (MM) Cohort: * Relapsed or refractory multiple myeloma after ≥1 prior line of therapy, including a proteasome inhibitor and an immunomodulatory agent, with disease refractory to lenalidomide (progression within 60 days of last lenalidomide dose) * Age ≥18 years * ECOG performance status ≤2 * Adequate organ function: ANC ≥1000 cells/mm³; platelet count ≥75,000 cells/mm³; creatinine clearance or eGFR ≥30 mL/min; total bilirubin ≤2.0x ULN; AST or ALT ≤3.0x ULN; left ventricular ejection fraction \>40% Exclusion Criteria: For DLBCL Cohort: * History of previous total body irradiation * Prior CAR T-cell therapy * Clonal cytopenia of uncertain significance (CCUS) * Prior history of myeloid malignancies (MDS/AML or MPN), T-cell lymphoblastic lymphoma/leukemia, or B-cell acute lymphoblastic leukemia * Current or prior CNS involvement by lymphoma * Significant cardiovascular impairment (CHF greater than NYHA Class II, uncontrolled hypertension, unstable angina, MI or stroke within 6 months, or cardiac ventricular arrhythmia) * Decompensated cirrhosis * Active HIV, hepatitis B, or hepatitis C infection * Active uncontrolled systemic fungal, bacterial, or viral infection * Pregnancy For MM Cohort: * History of previous total body irradiation * History of myelodysplastic syndrome, CCUS, or concurrent active hematological malignancy with bone marrow involvement * Active HIV, hepatitis B, or hepatitis C infection * Active uncontrolled systemic fungal, bacterial, or viral infection * Prior CAR T-cell therapy * Active or history of CNS myeloma or leptomeningeal infiltration * Pregnancy