Abstract 774P
Background
Previous studies have identified prognostic factors before lymphodepleting chemotherapy in patients with relapsed/refractory large B-cell lymphoma (r/r LBCL) undergoing chimeric antigen receptor (CAR) T-cell therapy, including metabolic tumor volume (MTV) and CD4/CD8 ratio. However, there are limited reports on prognostic factors before apheresis. This study evaluated the prognostic impact of MTV and CD4/CD8 ratio prior to apheresis. Additionally, we assessed the influence of bridging therapy (BT) on prognosis according to pre-apheresis risk status.
Methods
We retrospectively studied r/r LBCL patients who received CAR T-cell therapy at our institution from October 2020 to March 2024. All patients had FDG-PET/CT scans and CD4/CD8 ratio before apheresis. SUVmax was measured, and MTV was summed using 41% of SUVmax as the threshold.
Results
43 patients were analyzed with a median follow-up of 12.4 months for survivors (IQR: 6.6–20.6 months). The overall response rate was 70%. At the last follow-up, 16 patients (37%) had experienced progression and 12 (28%) had died. The median progression-free survival (PFS) was 26.6 months (95% confidence interval [CI]: 11.8–not reached). Using a median MTV cutoff value of 26.62mL (IQR; 1.74–93.3), patients were divided into high and low MTV groups. Patients with low MTV had significantly superior PFS (hazard ratio [HR], 0.25; 95% CI, 0.09–0.70). Based on a median CD4/CD8 ratio cutoff value of 0.64 (IQR: 0.31–0.84), patients were divided into high and low CD4/CD8 groups. Those with high CD4/CD8 had significantly superior PFS (HR, 0.37; 95% CI, 0.14–0.96). A new prognostic model combining MTV and CD4/CD8 ratio stratified patients into low risk (zero or one risk factor) and high risk (two risk factors) subgroups. The low-risk group (n = 30) had significantly superior PFS (HR, 0.14; 95% CI, 0.05–0.37). The response to BT was not significant for PFS in low-risk patients but was significant in high-risk patients (HR,0.19; 95% CI, 0.04–0.83).
Conclusions
High MTV and low CD4/CD8 ratio before apheresis correlated with poorer prognosis in CAR T-cell therapy for r/r LBCL. Effective BT improved outcomes in high-risk patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.