Abstract CT245: Circulating tumor DNA and nivolumab maintenance: A pilot study in diffuse large B cell lymphoma

Abstract Introduction: Molecular minimal residual disease (MRD) status correlates with disease relapse in patients (pts) with diffuse large B cell lymphoma (DLBCL). However, the clinical impact of early treatment intervention a time of detectable MRD (dMRD) prior to clinical relapse is unknown. Checkpoint inhibitor (CPI) therapy has activity in some pts with DLBCL. We hypothesized that early CPI therapy in patients with dMRD without clinical relapse may lower relapse rate. We conducted a pilot study in high risk pts in remission after most recent line of therapy (LOT) in whom maintenance nivolumab (MN) was offered at time of dMRD to assess effect on MRD clearance and relapse rate. Methods: Pts 18 years (yrs) with high-risk DLBCL (ABC-subtype, high grade B cell lymphoma (HGBCL), MYC translocation, relapsed/refractory disease, or Ki67 90%) who had achieved CR on most recent LOT were eligible. Patients were monitored for detectable MRD (dMRD) based on the clonoSEQ assay for circulating tumor DNA (ctDNA). Pts had monthly MRD assessment and every 4 month imaging for 2 yrs. If conversion from uMRD to dMRD without clinical relapse, pts received MN (240 mg IV q2 weeks) for up 2 yrs. Pts with overt relapse at time of dMRD or dMRD at initial MRD assessment were ineligible for MN. The primary endpoint was rate of conversion from dMRD to undetectable MRD (uMRD). Results: 20 pts were screened and 15 pts enrolled between June 2018 and March 2022. 4 had transformed DLBCL (2 from FL, 1 from MZL, and 1 Richter’s transformation from CLL), 2 pts had HGBCL (one of which was also transformed). All pts with dMRD had radiographic relapse within 4 months of molecular relapse. No pts with uMRD by ctDNA had clinical relapse on study during 2 yrs follow up. Of the 8 pts who enrolled after first LOT, none had molecular or clinical relapse. Of the 7 pts with 2+ prior LOT, 3 had dMRD: two had clinical relapse at same time as dMRD and were taken off study (one had dMRD at baseline MRD assessment and the other 135 days post enrollment after initial period of uMRD). In the single patient eligible for MN, dMRD preceded radiographic relapse by 105 days, 410 days after enrollment. The pt received 2 cycles of MN before clinical progression and was taken off study. This pt failed to achieve conversion of dMRD to uMRD. Conclusion: Due to small sample size and lower than expected relapse, we were unable to demonstrate conversion of dMRD to uMRD using MN. However, this pilot study did confirm high correlation of uMRD and dMRD status with disease free survival and clinical relapse within 4 months, respectively. If strong negative predictive value is confirmed in a larger study, ctDNA MRD testing may be used to spare pts from imaging or to guide additional work up in pts with inconclusive findings on scans. Citation Format: Shazia Nakhoda, Tamarrah Sklarz, Cheyenne Pagan, Matthew Matasar, Zachary A. Frosch, Marcus Messmer, Asya Varshavsky Yanovsky, Rashmi Khanal, Carlyn Tan, Eli Mikkelsen, Henry Fung, Eric Ross, Mark Roschewski, Allison Jacob, Nadia Khan. Circulating tumor DNA and nivolumab maintenance: A pilot study in diffuse large B cell lymphoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr CT245.