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ASTRO 2022: Using PET/CT Parameters to Predict Response to Immunotherapy for Diffuse Large B-Cell Lymphoma

By: Gavin Calabretta, BS
Posted: Friday, November 11, 2022

Hazim Ababneh, MD, of Massachusetts General Hospital, Boston, and colleagues analyzed a database of patients with diffuse large B-cell lymphoma to define the prognostic value of different PET/CT parameters. These findings, which the researchers presented at the 2022 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 251), suggested that disease features including metabolic tumor volume may predict patients’ response to chimeric antigen receptor (CAR) T-cell therapy.

The study enrolled 63 patients who had PET/CT scans before beginning CD19-targeted CAR T-cell therapy. The investigators analyzed the predictive and prognostic value of metabolic tumor volume, total lesion glycolysis, and standardized uptake value. A disease burden–based response evaluation was conducted after CAR T-cell therapy.

After a median follow-up of 10.7 months, the best objective overall and complete response rates were respectively 78% (n = 49) and 54% (n = 34) after CAR T therapy. The investigators reported that low metabolic tumor volume (odds ratio [OR] = 8.03; P = .001) and tumor lesion glycolysis (OR = 4.7; P =.01), before CAR T-cell therapy, were predictive of a complete response afterward; conversely, patients with a high metabolic tumor volume before therapy (OR = 4.04; P = .02) or tumor lesion glycolysis (OR = 3.6; P = .03) had an increased mortality risk. In addition, bulky disease (≥ 5 cm; hazard ratio [HR] = 6.08; 95% confidence interval [CI] = 2.6–14.2; P < .001), high metabolic tumor volume (HR = 2.4; 95% CI = 1.13–4.9; P = .022), and high tumor lesion glycolysis (HR = 2.35; 95% CI = 1.1–5.0; P = .026) were associated with inferior overall survival.

“There may be a role for pre–CAR T radiation therapy targeting bulky site(s) with high [fluorodeoxyglucose] avidity, regardless of symptoms, thereby reducing disease burden prior to CAR T-cell therapy,” the researchers commented. “[This] may lead to improved efficacy and reduced CAR T–related adverse events.”

Disclosure: Dr. Ababneh reported no conflicts of interest.

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