1. Unlocking Predictive Power: Quantitative Assessment of CAR-T Expansion with Digital Droplet Polymerase Chain Reaction (ddPCR)
- Author
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Galli, Eugenio, Viscovo, Marcello, Fosso, F., Pansini, Ilaria, Di Cesare, G., Iacovelli, C., Maiolo, E., Sora, F., Hohaus, Stefan, Sica, S., Bellesi, Silvia, Chiusolo, Patrizia, Galli E., Viscovo M., Pansini I., Hohaus S. (ORCID:0000-0002-5534-7197), Bellesi S., Chiusolo P. (ORCID:0000-0002-1355-1587), Galli, Eugenio, Viscovo, Marcello, Fosso, F., Pansini, Ilaria, Di Cesare, G., Iacovelli, C., Maiolo, E., Sora, F., Hohaus, Stefan, Sica, S., Bellesi, Silvia, Chiusolo, Patrizia, Galli E., Viscovo M., Pansini I., Hohaus S. (ORCID:0000-0002-5534-7197), Bellesi S., and Chiusolo P. (ORCID:0000-0002-1355-1587)
- Abstract
Flow cytometry (FCM) and quantitative PCR (qPCR) are conventional methods for assessing CAR-T expansion, while digital droplet PCR (ddPCR) is emerging as a promising alternative. We monitored CAR-T transcript expansion in 40 B-NHL patients post-infusion of CAR-T products (axi-cel; tisa-cel; and brexu-cel) with both His-Tag FCM and ddPCR techniques. Sensitivity and predictive capacity for efficacy and safety outcomes of ddPCR were analyzed and compared with FCM. A significant correlation between CAR-T counts determined by FCM and CAR transcripts assessed by ddPCR (p < 0.001) was observed. FCM revealed median CD3+CAR+ cell counts at 7, 14, and 30 days post-infusion with no significant differences. In contrast, ddPCR-measured median copies of CAR-T transcripts demonstrated significant lower copy numbers in tisa-cel recipients compared to the other products at day 7 and day 14. Patients with a peak of CAR transcripts at day 7 exceeding 5000 copies/microg gDNA, termed “good CAR-T expanders”, were more likely to achieve a favorable response at 3 months (HR 10.79, 95% CI 1.16–100.42, p = 0.036). Good CAR-T expanders showed superior progression-free survival at 3, 6, and 12 months compared to poor CAR-T expanders (p = 0.088). Those reaching a peak higher than 5000 copies/microg gDNA were more likely to experience severe CRS and ICANS. DdPCR proves to be a practical method for monitoring CAR-T expansion, providing quantitative information that better predicts both treatment outcomes and toxicity.
- Published
- 2024