Combined ibrutinib and venetoclax for mantle cell lymphoma

This study investigated the safety and effectiveness of ibrutinib (Imbruvica) plus venetoclax (Venclexta) for the treatment of mantle cell lymphoma. This study concluded that this regimen improved outcomes in patients with mantle cell lymphoma.

The standard treatment for mantle cell lymphoma (MCL) is rituximab combined with other drugs, although chemotherapy is also used. For patients with refractory (does not respond to treatment) disease, ibrutinib has become the preferred standard of care.

Ibrutinib and venetoclax are targeted therapies. This type of treatment blocks proteins involved in cancer cell growth and function. This leads to cancer cell death. Whether combined ibrutinib and venetoclax is more effective than either drug alone for MCL remains under investigation.

This study involved 24 patients with mantle cell lymphoma. 95.8% of patients had relapsed or refractory disease. Patients were given ibrutinib alone for the first 4 weeks. Ibrutinib and venetoclax were then given for the rest of the study. The average treatment time was 14.4 months. The average follow-up period was 15.9 months.

Overall, 71% of patients responded to treatment after 16 weeks. Of these, 62% achieved a complete response (disappearance of all signs of cancer).

The average 1-year progression-free survival (PFS; patients alive without a return of disease) was 75%. The average 1-year overall survival (OS; patients still alive 1 year later) was 79%. At 18 months, PFS was 57% and OS was 74%.

33.3% of patients experienced disease progression. Of these, 62.5% had refractory disease and 37.5% had a relapse. These patients all discontinued treatment.

Most of the reported side effects were mild. These included diarrhea (83%), fatigue (75%), and nausea or vomiting (71%). 58% of patients reported severe side effects. These included low white blood cell count (33%), low platelets (17%) and low red blood cells (12%). Tumor lysis syndrome (a toxic side effect following the death of cancer cells) occured in two high-risk patients, which led to the starting dose of venetoclax being reduced. 

This study concluded that ibrutinib plus venetoclax improved outcomes for patients with mantle cell lymphoma, particularly those who would have had poor outcomes with current therapy.

The patient population and follow-up period in this study were small. Also, the complete response rates ranged from 42 – 71% depending on how they were measured. Both CT scans and PET scans were used.