Remission Assessment by Circulating Tumor DNA in Large B-cell Lymphoma.

PURPOSE

Large B-cell lymphomas (LBCL) are curable, but patients with residual disease after therapy invariably experience progression. Ultrasensitive methods to detect circulating tumor DNA (ctDNA) as minimal measurable residual disease (MRD) may improve the determination of remission.

METHODS

We integrated data from five prospective studies of frontline anthracycline-based chemotherapy in patients with LBCL. Tumor-specific phased variants were identified from pretreatment samples and monitored at landmark timepoints. Serial plasma specimens were blindly analyzed for detectable ctDNA as MRD. MRD status was compared to conventional response criteria for prognosis of progression-free survival (PFS).

RESULTS

We studied ctDNA-MRD in 137 patients by monitoring 409 plasma specimens over time. Detectable ctDNA rates decreased during therapy with 55% and 78% of patients achieving undetectable ctDNA after 2 cycles and at end of therapy, respectively. After a median follow-up of 37 months, the 2-year PFS for patients with detectable vs undetectable ctDNA after 2 cycles was 67% vs 96% (p=0.0025, hazard ratio 6.9) and after therapy was 29% vs 97% (p<0.0001, hazard ratio 28.7), respectively. Ninety-two (94%) patients with undetectable ctDNA at end of therapy remained alive without progression, while 19 (68%) patients with detectable ctDNA progressed or died. MRD status at end of therapy had greater prognostic utility than conventional lymphoma response criteria using PET scans (hazard ratio 3.6 for positive PET, and 28.3 for detectable ctDNA).

CONCLUSION

Ultrasensitive circulating tumor DNA detection after frontline LBCL therapy is more prognostic than conventional radiographic response criteria. A refined definition of remission with ctDNA-MRD may improve clinical and psychological outcomes for patients with LBCL (Funded by the National Cancer Institute and others; ClinicalTrials.gov numbers, NCT04002947; NCT00398177; NCT02529852; NCT04231877; NCT04134936).