Peripheral Blood CD4 / CD8 Ratio Predicts Out‐of‐Specification Products in Lisocabtagene Maraleucel Manufacturing

Background Lisocabtagene maraleucel (liso‐cel) is a CD19‐directed chimeric antigen receptor T‐cell therapy for patients with relapsed or refractory large B‐cell lymphoma. Methods In this retrospective study involving 22 patients, we evaluated the association between peripheral blood CD4/CD8 ratios and the occurrence of out‐of‐specification (OOS) products during manufacturing. Expanded access protocols have permitted the infusion of OOS products, despite their failure to meet commercial release criteria, under close regulatory oversight. Results Five patients who received OOS products had significantly lower CD4/CD8 ratios (median 0.22 vs. 0.46; p = 0.008). Conclusion Our findings suggest that a low CD4/CD8 ratio (below one‐third) may be a predictive marker for OOS outcomes, potentially supporting patient selection and treatment planning. Therefore, prospective validation using a larger cohort is warranted.