Molecular and genetic biomarkers implemented from next-generation sequencing provide treatment insights in clinical practice for Waldenström macroglobulinemia

Abstract

Waldenström macroglobulinemia (WM) is a distinct type of indolent lymphoplasmacytic lymphoma (LPL) with a high frequency of MYD88^L265P mutation. Treatment for WM/LPL is highly variable in clinic and ibrutinib (a Bruton tyrosine kinase inhibitor, BTKi) has become a new treatment option for WM. To investigate the clinical impact of genetic alterations in WM, we assembled a large cohort of 219 WMs and 12 LPLs dividing into two subcohorts: a training cohort, patients sequenced by a same targeted 29-gene next-generation sequencing (NGS) panel, and a validation cohort, patients sequenced by allele specific-PCR or other targeted NGS panels. In both training and validation subcohorts, MYD88^L265P and TP53 mutations showed favorable and adverse prognostic effects, respectively. CXCR4 nonsense/missense mutations (CXCR4^NS/MS), cytogenetic complex karyotypes, and a family history of lymphoma/leukemia in first-degree relatives were associated with significantly worse clinical outcomes only or more in the validation subcohort. We further investigated the efficacy of various treatments and interaction with genetic factors in the entire cohort. Upfront dexamethasone usage was associated with poorer clinical outcomes in patients who received non-proteasome-containing chemotherapy as first-line treatment independent of genetic factors. Maintenance rituximab was associated with better survival. Ibrutinib/BTKi showed potential benefit in relapsed/refractory patients and patients without CXCR4^NS/MS including those with TP53 mutations. In conclusion, genetic testing for MYD88^L265P, TP53, and CXCR4 mutations and cytogenetic analysis provide important information for prognosis prediction and therapy selection. The findings in these study are valuable for improving treatment decisions on therapies available for WM/LPL patients with integration of NGS in clinic.

Keywords: CXCR4; Cytogenetic karyotype; Ibrutinib; MYD88; TP53; Waldenström macroglobulinemia.

Fig. 1

Mutational analysis in 68 patients with WM/LPL who were analyzed by NGS with a same 29-gene somatic mutation analysis panel (training set). (A) Case distribution of somatic mutations detected by the NGS panel, mutation frequencies, and case distribution of genetic and treatment factors in the training set. In the case distribution plots, each cell/box represents one patient. (B)MYD88 mutation (L265P) was associated with a trend of better OS in overall cases, a significantly better OS and a trend of better OS1 in treated symptomatic patients. (C-D)TP53 mutation was associated with significantly worse OS and PFS rates in overall patients and significantly shorter time-to-treatment and post-treatment OS1/PFS1 in treated patients. LPL, lymphoplasmacytic lymphoma; NGS, next-generation sequencing; WM, Waldenström macroglobulinemia.

Fig. 2

Mutational analysis in patients sequenced by AS-PCR or a NGS panel different from the 29-gene somatic mutation analysis panel (validation set). (A) Mutation frequency of somatic mutations detected and case distribution of genetic and treatment factors in sequenced patients. In the case distribution plot, each cell/box represents one patient; cases with specific mutations and treatment are highlighted in corresponding colors; cases not assessed for mutations and other factors are filled with olive green color and diagonal stripes. (B)MYD88 mutation (L265P) was associated with a significantly better OS and a trend of better PFS in overall patients and significantly longer time-to-treatment and a nonsignificant trend of better post-treatment OS1 in treated patients. (C)TP53 mutation was associated with shorter time-to-treatment in treated patients with a border-line P value. (D)CXCR4 mutation (nonsense or missense) was associated with significantly shorter time-to-treatment and post-treatment OS1 in treated patients. (E) Complex karyotype was associated with significantly shorter time-to-treatment in treated patients in the validation subcohort.

Fig. 3

Survival analysis for cytogenetic karyotypes and family history in patients with WM/LPL. (A) Complex karyotype was associated with significantly poorer OS/PFS in the entire study cohort and significantly poorer post-treatment PFS1 in treated patients in the entire cohort and the validation subcohort. (B) WM/LPL patients whose first-degree relatives had lymphoma or leukemia incidence had significantly shorter OS and post-treatment OS1 than those without such family history in the entire study cohort, a poorer post-treatment PFS1 in the training subcohort, and a poorer post-treatment OS1 in the validation subchort.

Fig. 4

Therapeutic efficacy analysis for the diverse frontline regimens in treated patients with WM/LPL. (A) Comparison of post-treatment PFS1 and OS1 of patients receiving various frontline regimens. Frontline BDR (bortezomib, dexamethasone, and rituximab) was associated with a significantly poorer PFS1. (B) Bortezomib inclusion in frontline treatment analyzed as a prognostic factor was associated with a significantly poorer PFS1 in WM/LPL. (C) Dexamethasone usage in frontline treatment was associated with significantly worse post-treatment PFS1 rates in overall cohort and the subcohort with chemotherapy as frontline treament, and associated with a significantly worse OS1 in patients who received chemotherapy without proteasome inhibitor (PI) combination in frontline treatment.

Fig. 5

Therapeutic analysis in treated patients with WM/LPL. (A) Maintenance therapy with either rituximab (R) alone or R-containing regimens after first-line treatment was associated with a significantly better post-treatment PFS1. (B) Rituximab-based maintenance therapy after any-line treatment, but not other type of maintenance therapies, was associated with significantly better PFS1 and OS1. (C) Ibrutinib-based treatment in the relapsed/refractory setting was associated with a significantly better PFS after ibrutinib treatment compared with the PFS after first-line treatment. (D) Case distribution plot for various regimens in treated symptomatic patients.

Fig. 6

Therapeutic analysis in WM/LPL patients with unfavorable genetic factors. (A-B) Frontline dexamethasone was associated with significantly poorer post-treatment PFS1/OS1 in patients with TP53 mutation or with wild-type MYD88. (C) Frontline dexamethasone was associated with significantly poorer post-treatment PFS1 in patients with complex cytogenetic karyotype or CXCR4 mutation (nonsense or missense). (D) In patients treated with BTK inhibitors (regardless of line of the treatment), CXCR4 mutation (nonsense or missense) was associated with significantly worse OS. (E) In patients with TP53 mutation but not CXCR4 nonsense/missense mutation, single-agent ibrutinib as first-line treatment was associated with a trend of better PFS1 after treatment.