CAR T-Cell Expansion Predicts Toxicity, But Not Always Efficacy

At the 2026 National ICE-T Conference in Orlando, a session titled “Thresholds and Therapeutics: A Precision Approach to CAR T Toxicity Management” examined how biomarkers, including CAR T-cell expansion, may help clinicians anticipate toxicity risk with anti-BCMA CAR T-cell products.¹

Presenter Tiba Al Sagheer, PharmD, BCOP, BCACP, pharmacy quality improvement coordinator for transplant and cellular therapy at Miami Cancer Institute of Baptist Health South Florida, spoke with CancerNetwork^® about how balancing early toxicity intervention against the risk of blunting efficacy differs by CAR T-cell product.

Transcript:

CancerNetwork: Speaking as a pharmacist, how do you balance early aggressive intervention against the risk of blunting CAR T-cell efficacy by dampening the immune response too soon?

When we say CAR T, there are many products and many targets. We have the CD19 products and the anti-BCMA CAR products. One of the topics I went over is that with the anti-BCMA CAR products—ciltacabtagene autoleucel [cilta-cel; Carvykti] and idecabtagene vicleucel [ide-cel; Abecma]—and CAR expansion, meaning how quickly or robustly the CAR expands in the body, there was no correlation between the efficacy of the CAR product and its expansion for cilta-cel, but there was a correlation between expansion and toxicity. Bigger expansion, more toxicity. But that is not the story with ide-cel; [with] larger expansions, we saw better clinical outcomes.

That is why it is important for us to know whether we are going to restrict the expansion of both products by looking at markers like the absolute lymphocyte count [ALC], which can tell us a patient is going to have greater toxicity. It is not just 1 thing we want to look at; it is multifactorial. There is a model called the NEMO model—just like Finding Nemo—developed by a group in Seattle that takes into account ALC in addition to CRP, platelets, and ferritin at that time point, and stratifies patients to know if they will develop higher-grade toxicities and need treatment.²

References

1. Sagheer TA. Thresholds and therapeutics: a precision approach to CAR T toxicity management. Presented at the 2026 National ICE-T Conference; July 18, 2026; Orlando, FL.
2. Jeon Y, Wu X, Khouderchah C, et al. NEMO: a novel prognostic model of non-ICANS neurotoxicities associated with ciltacabtagene autoleucel. Transplantation and Cellular Therapy. 2026;32(2):S12-S13. doi:10.1016/j.jtct.2025.12.028