Persistent Overall Response on Early PET/CT Scans during Salvage Therapy for Relapsed or Refractory DLBCL Predicts for Disease Specific Survival

• Published in: Blood 2020-11, Vol.136 (Supplement 1), p.7-8
• Main Authors: Cherng, Hua-Jay J, Steiner, Raphael E, Fayad, Luis, Strati, Paolo, Nair, Ranjit, Hagemeister, F. B.B., Nastoupil, Loretta J., Lee, Hun Ju, Neelapu, Sattva S., Flowers, Christopher, Samaniego, Felipe, Rodriguez, Maria Alma, Feng, Lei, Chuang, Hubert, Westin, Jason R.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2020-134203

Background Patients (pts) with relapsed or refractory (R/R) diffuse large b-cell lymphoma (DLBCL) can achieve cure with platinum-containing chemotherapy (PCC) and autologous stem cell transplant (autoSCT). Only half of pts respond to PCC based on a positron emission tomography/computed tomography (PET/CT) scan after 2 cycles, but most experience significant toxicity. Minimizing exposure to PCC for non-responders in favor of other treatments such as anti-CD19 CAR T-cell therapy (CART19) is important. We hypothesized that PET/CTs performed earlier during salvage therapy could predict end-of-treatment (EOT) response and survival. We conducted an investigator initiated single-institution pilot study (NCT02405078) where 2 early PET/CTs were obtained during cycle 1 (C1) of salvage PCC. Methods Adult R/R DLBCL pts eligible for PCC with a pre-therapy PET/CT were eligible for enrollment. The PCC regimen was selected by the treating physician. The primary endpoint was EOT response. PET/CTs were obtained on D4 and D21 of C1 of PCC, and at EOT after 2-3 cycles. Treating physicians were not blinded to early PET/CT results. Disease-specific survival (DSS) was defined as time from D1 of C1 of salvage PCC to death from DLBCL. Results A total of 25 pts with a median age of 61 years (range 25-82) at relapse treated with PCC between 2/5/2016 and 10/30/2018 were included in the analysis, with data cutoff as of 2/29/2020. Selected baseline pt characteristics are as follows: 68% were GCB cell-of-origin by Hans algorithm, 60% were stage III/IV, 88% had an ECOG PS < 2, 44% an international prognostic index (IPI) ≥3, and 32% double-hit lymphoma. Median time from initial diagnosis to first progression was 5.8 months. Therapies received were R-DHAP (44%), R-ICE (36%), and other regimens (20%). Ten (40%) pts had a therapy change after C1 and before EOT evaluation due to early treatment failure or progression based on early PET/CT result as interpreted by the treating physician. Twelve (48%) continued with a second cycle of the same regimen, and 3 discontinued therapy. Sixteen (64%) pts were evaluable for EOT response by PET/CT, while 7 (28%) pts were missing an EOT PET/CT due to early progression and 2 for other reasons. The only baseline characteristic different between EOT responders, non-responders, and pts missing EOT evaluation due to early progression was time from initial diagnosis to progression (8.6 vs. 5.3 vs. 4.5 months, p=0.035). Overall response (OR; complete or partial