A new study suggests that in patients with relapsed/refractory large B-cell lymphoma (LBCL), the early use of fluorodeoxyglucose (FDG)-positron emission tomography (PET) may help predict future failure with chimeric antigen receptor (CAR) T-cell therapy. The study results were published in the journal Blood Advances.

FDG-PET imaging has been used for assessing response or prognosis in patients with LBCL, but this had not previously been evaluated for patients treated with CAR-T therapy, the study authors explained in their report. 

The study was a retrospective analysis of patients with LCBL receiving CAR-T therapy and treated across 3 hospitals in the UK. Evaluable patients had responses assessed at 1 month and a follow-up of 3 or more months. FDG-PET imaging was performed at approximately 1 month, 3 months, and 6 months following infusion of CAR-T cells. Response was evaluated using the 5-point Deauville score (DS) system, with a subcategory of DS4 additionally used for cases involving bridging radiotherapy in which DS4 uptake was restricted to the radiotherapy field, and this category was notated as DS4RT.


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FDG-PET was evaluated in 171 patients at month 1 and in 170 patients at months 3 and 6. At month 1, the overall response rate was 76%, with 42% of patients showing complete response (CR) and 34% showing partial response (PR). With the DS system, DS1-2 responses at 1 month were seen in 31% of patients, DS3 response was seen in 24%, DS4 response was seen in 35%, and a PR DS5 response was seen in 10%.

The risk of progressive disease (PD) at 6 months was 15% for patients with DS1-2 response, 10% for patients with DS4RT response, 32% with DS3 response, 46% for DS4 response (excluding DS4RT), and 100% with a DS5 response. Higher preinfusion lactate dehydrogenase and C-reactive protein levels were associated with having more transient, compared with durable, responses, and lower DS scores were associated with greater durability of response. However, DS status was the only factor significantly associated with time to relapse in multivariable analysis.

DS status at the 1-month evaluation was also linked to progression-free survival (PFS) and overall survival (OS) rates. The 12-month PFS rate was as high as 77.1% with DS1-2/DS4RT status, while for patients with DS5 status it was 0%. The 12-month OS rate for patients with DS1-2/DS4RT status was 87.1%, and for patients with DS5 status it was 38.1%.

“In conclusion, our results indicate that early FDG-PET DS categories provide a standardized, broadly available tool to predict durable remission after CD19 CAR-T and could inform early post-CAR-T management and response-adapted stratification in clinical trials,” the study authors wrote in their report.

Disclosures: Some authors have declared affiliations with or received grant support from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.

Reference

Kuhnl A, Roddie C, Kirkwood AA, et al. Early FDG-PET response predicts CAR-T failure in large B-cell lymphoma. Blood Adv. 2022;6(1):321-326. doi:10.1182/bloodadvances.2021005807