Comparison of venetoclax plus rituximab with B-cell receptor inhibitors in patients with relapsed/refractory chronic lymphocytic leukemia: a systematic review and network Meta-analysis

Network meta-analysis of novel targeted therapies for relapsed/refractory chronic lymphocytic leukemia

Background

The recent development of new antileukemic therapies (anti-CD20 monoclonal antibodies, Bruton tyrosine kinase inhbitors, phosphoinositide 3-kinase inhibitors, and B-cell lymyphoma-2 antagonists) improved the progression-free survival (PFS) compared with selected standard regimens in clinical trials for patients with relapsed/refractory chronic lymphocytic leukemia (CLL). Unfortunately, the relative efficacy of all possible therapeutic options remains unknown because there is no direct evidence for all possible comparisons.

Objectives

We aimed to compare the efficacy and safety of novel agents, chemotherapy, and immunotherapy using a Bayesian network meta-analysis (NMA).

Design

Systematic literature review with Bayesian NMA.

Methods

An extensive systematic literature review of randomized clinical trials for relapsed/refractory CLL was performed. We searched for articles indexed in medical databases (MEDLINE, Embase, The Cochrane Library) and gray literature that could be further implemented into the Bayesian NMA.

Results

The systematic search identified 15 randomized trials that formed networks comparing PFS, overall survival (OS), overall response rates, and serious adverse events. Our study showed that all regimens containing novel agents significantly prolonged PFS compared with standard chemoimmunotherapy and immunotherapy. Among targeted drugs, venetoclax (VEN) + rituximab (RTX) had comparable efficacy in terms of PFS to zanubrutinib (ZAN) [hazard ratio (95% credible interval), 1.10 (0.59-2.08)], acalabrutinib (ACA) [0.78 (0.47-1.30)], ibrutinib (IBR) monotherapy [0.72 (0.41-1.27)], and other IBR-based regimens. ZAN was superior to IBR monotherapy [0.65 (0.49-0.86)] but not to ACA [0.71 (0.49-1.02)]. There were no significant differences in OS in any of the above comparisons.

Conclusion

All novel therapies have better efficacy than chemoimmunotherapy and immunotherapy regimens. Among novel agents, the relative efficacy of VEN + RTX was similar to all BTKi, while ZAN was superior to IBR and comparable to ACA.

Trial registration

PROSPERO CRD42022304330.

Comparative Clinical Value of Pharmacologic Therapies for B-Cell Chronic Lymphocytic Leukemia: An Umbrella Analysis

Several new drugs are progressively improving the life span of patients with B-cell chronic lymphocytic leukemia (CLL). However, the rapidly evolving standard of care precludes robust assessments of the incremental clinical value of further innovative drugs. Therefore, we systematically reviewed comparative evidence on newly authorized CLL drugs, as reported by standard and network meta-analyses (MA) published since 2016. Overall, 17 MAs addressed the relative survival or safety of naïve and/or refractory/relapsed (R/R) CLL patients. In R/R patients, therapies including BTK- and BCL2-inhibitors reported progression free survival (PFS) hazard ratios ranging from 0.08 to 0.24 (versus chemotherapy) and a significant advantage in overall survival (OS). In naïve patients, the PFS hazard ratios associated with four recent chemo-free therapies (obinutuzumab- and/or acalabrutinib-based) ranged from 0.11 to 0.61 versus current standard treatments (STs), without a significant OS advantage. Ten MAs addressed the risk of cardiovascular, bleeding, and infective events associated with BTK inhibitors, with some reporting a different relative safety in naïve and R/R patients. In conclusion, last-generation therapies for CLL consistently increase PFS, but not OS, and minimally decrease safety, as compared with STs. Based on available evidence, the patient-customized adoption of new therapies, rather than universal recommendations, seems desirable in CLL patients.

The Evolution of Targeted Therapies in Chronic Lymphocytic Leukaemia

PURPOSE OF REVIEW

The treatment landscape for chronic lymphocytic leukaemia (CLL) is rapidly evolving, with several targeted agents recently approved. These compounds have dramatically changed the natural history of the disease.

RECENT FINDINGS

However, with the array of effective therapies commercially available, the challenge is to define tailored treatment strategies able to realize a balance between treatment efficacy and toxicity or tolerance. New algorithms of treatment are being developed, and it appears that minimal residual disease (MRD) directed therapy will become the norm in the future. Clinical trials are looking at various combinations of novel therapies given with a defined, fixed-period of treatment based on MRD analysis. This approach enables patients to have a period of treatment-free remission instead of continuous therapy. In this review, we summarize this evolution of targeted therapies in CLL.

Treatment algorithm for Japanese patients with chronic lymphocytic leukemia in the era of novel targeted therapies

Treatment for patients with chronic lymphocytic leukemia (CLL) is becoming more individualized due to the recent introduction of novel molecularly targeted therapies into the therapeutic armamentarium. Genomic and molecular risk factors in CLL patients determine the individual risk for disease progression and response to therapy, and can impact survival. In this review article, we discuss current treatment strategies for CLL patients in Japan, where the novel targeted agents, the BTK inhibitor ibrutinib and BCL2 antagonist venetoclax, now are available and increasingly used in clinical practice. We also discuss the importance of CLL risk factors for making therapy decisions, focusing on immunoglobulin variable region heavy chain (IGHV) mutation status, 11q deletion, and 17p deletion. Treatment approaches for CLL have rapidly changed in the past few years because of these new targeted agents. They are highly effective, well tolerated, and have been demonstrated in a series of large randomized clinical trials to improve survival when compared with conventional chemotherapy-based treatment. Therefore, for most patients, especially high-risk CLL patients, BTK inhibitor and BCL2 antagonist therapies are preferred over chemo-immunotherapy. Currently ongoing studies seek to determine the best sequence for these new agents and whether a combination therapy approach is beneficial. With these developments, a new era of chemotherapy-free treatment for CLL patients is expected.

Current Treatment of Refractory/Relapsed Chronic Lymphocytic Leukemia: A Focus on Novel Drugs

Recently, the use of novel targeted drugs has changed the treatment paradigms in chronic lymphocytic leukemia (CLL). Among the several drugs used for the management of relapsed/refractory (R/R) CLL, Bruton tyrosine kinase inhibitors (ibrutinib and acalabrutinib), phosphatidylinositol 3-kinase inhibitors (idelalisib and duvelisib), B-cell lymphoma 2 inhibitor (venetoclax), and novel CD20 monoclonal antibodies have demonstrated the greatest improvements in survival among R/R CLL patients. However, patients with relapsed but asymptomatic CLL do not need immediate alternative treatment and should be observed until evident sign of progression. Among available approved treatments, venetoclax + rituximab for 24 months or ibrutinib as continuous therapy is recommended. Another, less recommended, option is idelalisib in combination with rituximab. The correct treatment selection depends on the type of prior therapy, response to previous treatment and side effects, presence of comorbidities, and the risk of drug toxicity. Allogeneic hematopoietic stem cell transplantation and investigational therapies such as chimeric antigen receptor-T-cell therapy are promising treatment options for high-risk patients, including those progressing after 1 or more targeted therapies. The present review discusses current treatment strategies for patients with R/R CLL.