While in vivo CAR-T therapies eliminate complex ex vivo manufacturing, they introduce a new critical variable: the patient's own immune system. The therapy's efficacy relies on modifying T-cells within the body, but each patient's immune status is different, especially after prior treatments. This makes optimizing and standardizing the dose a significant challenge compared to engineered cell therapies.

In follicular lymphoma, the treatment goal is durable remission with manageable toxicity, not necessarily a cure. Therefore, clinicians frequently prefer using a bispecific antibody first, reserving the more complex and toxic CAR-T cell therapy for transformed disease or after a bispecific fails.

Experts now view a patient's response to bridging therapy as a key predictor of CAR T outcomes. A patient who fails to respond or progresses during bridging has a much higher risk of toxicity and poor efficacy and should be considered for alternative treatments.

Clinical trials for second-line DLBCL used a 12-month relapse cutoff for eligibility, but this shouldn't be interpreted rigidly in practice. A patient relapsing at 13 months is biologically similar to one at 11 months and should still be strongly considered for CAR T-cell therapy over salvage chemotherapy and transplant.

Clinicians should not be deterred from using CD19 CAR T-cell therapy in patients who have previously received other CD19-targeting agents like tafasitamab. Preclinical and retrospective clinical data suggest prior exposure does not impair CAR T efficacy, and therefore re-testing for CD19 expression is unnecessary.

For mantle cell lymphoma patients on a BTK inhibitor who are progressing, the drug should be continued until immediately before leukapheresis for CAR T-cell therapy. Abruptly stopping the BTKi can lead to an explosive disease flare, potentially making the patient too unstable to proceed with T-cell collection.

Using a BCMA bispecific antibody first can exhaust a patient's T-cells or cause tumors to lose the BCMA target, rendering a subsequent BCMA-targeted CAR-T therapy ineffective. The optimal sequence is CAR-T first, which preserves T-cell function and BCMA expression, leaving bispecifics as a viable later-line option.

The TRANSFORM study quantifies the critical importance of therapy timing. DLBCL patients receiving Liso-cel CAR-T as a second-line treatment had a 95% two-year overall survival, which dropped significantly to 78% for patients who received it third-line after crossover from the standard-of-care arm.

Current CAR-T therapy for CLL requires a complete response (CR) for long-term benefit. A partial response provides only about two years of disease control, an outcome similar to the oral drug pirtobrutinib but with significantly more toxicity, complexity, and logistical burden for the patient.