Evaluating a triplet regimen for patients with relapsed or refractory MM after lenalidomide therapy

This study examined if PBD (pomalidomide, bortezomib, dexamethasone) was safe and effective in patients with multiple myeloma after lenalidomide (Revlimid) treatment. The authors concluded that pomalidomide improved survival without tumor growth or spread but increased side effects.

Multiple myeloma (MM) is a type of cancer of the bone marrow that can lead to abnormal immune cells. Lenalidomide is a common agent given during initial treatment. However, many patients become refractory to the drug during treatment. This means that the cancer stops responding to lenalidomide.

Triplet regimens containing three different agents may lead to better outcomes compared to regimens with fewer agents. Combining three agents may help induce a response in refractory disease. The PBD (pomalidomide, bortezomib, dexamethasone) regimen has shown promising results in initial studies. Pomalidomide is similar to lenalidomide but is more potent. Whether this regimen is effective in patients with MM that stopped responding to lenalidomide is unclear.

This study had 559 patients with relapsed or refractory MM. All patients were previously treated with lenalidomide. In this study, 281 patients received PBD, and 278 patients received BD (PBD without pomalidomide). Patients were followed for an average of 15.9 months.

Overall, patients who received PBD had a 39% lower risk of tumor growth or spread compared to the BD regimen. Patients who received PBD survived for significantly longer without tumor growth or spread compared to the BD group (11.2 months vs. 7.1 months). 

Patients who received PBD had a 5 times higher response rate to treatment compared to patients who received BD. 82.2% of patients who received PBD responded to the treatment compared to 50% of patients who received BD.

Side effects occurred more frequently in the PBD group compared to the BD group. The most common side effects were low white blood cells (42% vs. 9%) and infections (31% vs. 18%). Low platelet count (cells involved in blood clotting) was similar between both groups (27% vs. 29%). Serious side effects were also more common in the PBD group compared to the BD group (57% vs. 42%). However, slightly more patients in the BD group stopped treatment due to side effects (18% vs. 11%).

This study found that adding pomalidomide to bortezomib and dexamethasone improved treatment outcomes for patients with relapsed or refractory MM. However, pomalidomide was associated with more side effects.

The manufacturer of pomalidomide, Celgene, funded this study. This study is also limited by its short follow-up period.

Talk to your doctor about alternative drug options to treat relapsed or refractory MM.