Prognostic relevance of immunoglobulin heavy chain rearrangement and immunoglobulin kappa light chain rearrangement in patients with diffuse large B cell lymphoma.

Purposes: Evidence has demonstrated that monitoring of the variable, diversity, and joining gene segments (VDJ) rearrangement of immunoglobulin (Ig) gene in the circulating tumor DNA (ctDNA) is highly valuable in predicting the prognosis of patients with diffuse large B cell lymphoma (DLBCL). In this study, we investigated the role of both Ig heavy chain (IGH) and Ig kappa light chain (IGK) gene rearrangements detected in ctDNA samples in predicting DLBCL progression.

Methods: Next-generation sequencing (NGS) was used to identify the dominant V(D)J clonotypic rearrangement in tissue samples of 33 DLBCL patients. Minimal residual disease (MRD) was monitored at the interim and end of the treatment, as well as the follow-up time by tracking the dominant V(D)J clonotypic rearrangement (defined as the "NGS MRD" method) in the peripheral blood (PB) ctDNA samples. The nomogram was established to predict the 12-month and 24-month progression-free survival (PFS) probability.

Results: Prior to treatment, the dominant clones identified in the tissue samples could be retrieved in tissue-matched PB of 26 (78.8%, 26/33) patients. The addition of IGK clones to IGH clones increased the MRD detection rate from 42.9% to 58.0% in the total series. NGS MRD and imaging scans showed poor concordance at the interim of treatment (Kappa = 0.24) and the follow-up time (Kappa = 0.28), and fair concordance at the end of treatment (Kappa = 0.46). However, we confirmed that the interim NGS MRD monitoring demonstrated improved prognostic performance compared to imaging scans, and both NGS MRD monitoring and imaging scans served as valuable prognostic factors for PFS at the end of treatment. Notably, NGS MRD monitoring predicted disease relapse in 3 patients prior to imaging scans. Furthermore, we found that both the faster IGH and IGK clone clearance rates were associated with favorable prognosis. The nomogram model identified IGH and IGK clone clearance rates, together with the interim NGS MRD result were the important predictors of 12-month and 24-month progression of DLBCL.

Conclusions: MRD monitoring via NGS of Ig for both IGH and IGK is a promising noninvasive tool for prognosis prediction and early relapse prediction of DLBCL patients.