Change in IgHV Mutational Status of CLL Suggests Origin From Multiple Clones

Prognostic and Predictive Effect of IGHV Mutational Status and Load in Chronic Lymphocytic Leukemia: Focus on FCR and BR Treatments

BACKGROUND

Most important markers in chronic lymphocytic leukemia (CLL) are TP53 abnormalities, including mutations and deletions, and the mutational status of immunoglobulin heavy chain (IGHV) genes. However, some recent publications suggest that the IGHV mutational load could have a prognostic effect on CLL patients.

PATIENTS AND METHODS

We performed a single-center retrospective study on 459 patients with productive rearrangement of the B-cell receptor to evaluate the prognostic and predictive role of IGHV mutational status and burden within the germline sequence. In particular we focused on FCR (fludarabine with cyclophosphamide, and rituximab)- (64 naive and 30 relapsed) and BR (bendamustine with rituximab)-treated patients (17 naive and 61 relapsed). A cutoff value of 2% of difference within the IGHV germline was used to define the IGHV mutational status.

RESULTS

We reported that unmutated IGHV (U-IGHV) patients were characterized by a significant shorter progression-free survival (PFS) and overall survival (P < .0001) compared with mutated IGHV (M-IGHV) patients. Moreover, treatment-naive M-IGHV patients experienced a long-term disease control after FCR or BR, with PFS reaching a plateau regardless of mutational load. In our series the extent of IGHV gene mutation did not provide further relevant prognostic data over the mutational status. Relapsed patients showed dismal outcome with chemoimmunotherapy regardless of IGHV status or load.

CONCLUSION

Our data, together with from those from the literature, confirmed the cutoff value of 2% to define the mutational status of IGHV gene and suggest that FCR/BR are good first-line treatment strategies for M-IGHV patients, whereas U-IGHV patients should be managed with B-cell receptor and/or B-cell lymphoma 2 (BCL2) inhibitors.

IGHV mutational status testing in chronic lymphocytic leukemia

As the therapeutic landscape for chronic lymphocytic leukemia (CLL) continues to expand, biological predictors of response to therapy are becoming increasingly important. One such predictive biomarker is the mutational status of the variable region of the immunoglobulin heavy chain (IGHV) gene, which is a powerful predictor of duration of response and overall survival with chemoimmunotherapy (CIT). As this test may influence choice of therapy between CIT and novel agents, it is critical that providers understand how mutational status is determined and the limitations of testing. Here, we describe the details of IGHV mutational status testing, highlighting the appropriate way to interpret this information and best apply it to the care of patients with CLL.