Ibrutinib Combined With Rituximab for Treatment of Relapsed Refractory MYD88 and CD79A/B (or CD79B Alone) DLBCL Who Have Received at Least Two Prior Therapies

Overview

The purpose of this study is to evaluate the efficacy and safety of Ibrutinib Combined With Rituximab in Relapsed Refractory MYD88 and CD79A/B (or CD79B Alone) DLBCL Who Have Received at Least Two Prior Therapies.

Recent studies have found that about 30% of DLBCL have mutations in MYD88 and/or CD79A/B genes. MYD88 and CD79A/B protein molecules belong to two signal transduction pathways, which regulate B cell proliferation. Both MYD88 and CD79A/B gene mutations can abnormally activate BTK located downstream of MYD88 and CD79A/B, leading to over activation and proliferation of B cells. Ibrutinib is the first generation of oral BTKi, which may theoretically inhibit the tumorigenesis of DLBCL with abnormal BTK activation caused by mutations in MYD88 and CD79A/B genes. A phase II clinical study of ibrutinib monotherapy in the treatment of relapsed and refractory DLBCL showed that the effective rate of ibutinib for single CD79B mutation was 55.5% (5/9 cases), and that for both CD79B and MYD88 mutations was 80% (4/5 cases). About 40 \~ 50% of primary central nervous system large B cell lymphoma (PCNSL) have CD79B and MYD88 mutations. A small sample study found that the overall response rate (ORR) for the treatment of relapsed and refractory PCNSL with ibrutinib was 77% (10/13). An expanded sample study of 44 cases of PCNSL treated with ibrutinib found that the ORR is 52% and progression-free survival (PFS) is 4.8 months. These results suggest that ibrutinib may be more effective in DLBCL with MYD88 and CD79A/B or CD79B mutations. The relationship between mutations in MYD88 and CD79B and therapeutic sensitivity of ibrutinib can not be simply categorized, because abnormalities in other genes of B cell signaling pathway, such as CARD11, TNFAIP3, CXCR4, JAK1 and PIM1, may also affect the efficacy of ibrutinib. Therefore, it is necessary to comprehensively analyze the gene abnormalities of other B cell related signaling pathways, such as downstream signal of Bruton kinase, CXCR, JAK-STAT, and NFKB, to find out the most effective group of DLBCL patients treated with ibrutinib. This phase II, single-arm, open-label, multi-center clinical trial will evaluate the efficacy and safety of ibrutinib combined with rituximab in treating relapsed refractory MYD88 and CD79A/B (or CD79B alone) DLBCL who have received at least two prior therapies. The study will also explore the relationship between MYD88 and/or CD79A/B and efficacy, and detect the gene abnormality by Next Generation Sequencing (NGS) and evaluate the relationship between other gene abnormality and efficacy.