A successful case of venetoclax-based therapy in relapsed/refractory secondary plasma cell leukemia

Secondary plasma cell leukemia (sPCL) patients typically are either refractory to conventional therapies or have short remissions to drug regimens used in multiple myeloma (MM), which highlights sPCL's aggressive nature and association with advanced stage disease. t(11,14) is correlated with increased BCL-2 expression, which makes it a cytogenic marker of interest for use of the BCL-2 inhibitor venetoclax. Little data of venetoclax's use has been published in plasma cell leukemia. We present a case of a refractory/relapsed sPCL patient displaying t(11,14) who achieved a very good partial response (VGPR) from venetoclax therapy in combination with dexamethasone and bortezomib.

Our case describes a 67-year-old male initially diagnosed with IgG kappa MM in 2013, which transformed into non-secretory secondary plasma cell leukemia. Over a two-year period, despite responses to various therapies, the patient continued to experience relapses and exhausted options of novel agents seen in MM treatment. The patient was started on venetoclax in combination with bortezomib and oral dexamethasone.

Due to the patient's disease transformation into a non-secretory form of sPCL, PET/CT scans were relied upon to monitor disease progression. The PET/CT scan after three months of venetoclax combination treatment showed a very good partial response to therapy, with near resolution of metabolically active osseous disease.

The success of venetoclax-based therapy in achieving a very good partial response suggests its utility in relapsed/refractory sPCL patients, who have exhausted various combinations of drug regimens used in treatment of MM and have historically poor survival outcomes.