Three Cases of Lenalidomide Therapy for Multiple Myeloma and Subsequent Development of Secondary B-ALL.

INTRODUCTION: Multiple myeloma (MM) is the second most common hematological malignancy, accounting for 1% of all cancers, with median age of diagnosis between 66-70 years. MM remains incurable despite advances in treatment over time. Lenalidomide is an important medication used in induction therapy for MM and is also used for maintenance therapy for standard risk patients. With its increasing use, data is emerging about its use being associated with increased risk of secondary primary malignancies (SPM), especially when used as maintenance therapy. CASE SERIES: In this case series, we describe three patients with refractory MM treated with lenalidomide maintenance who later developed sALL. All had a common presentation of pancytopenia. They developed cytopenias while being on lenalidomide which was refractory to lenalidomide cessation, prompting bone marrow biopsy. MANAGEMENT AND OUTCOME: Lenalidomide was subsequently stopped, and patients were treated for secondary B-ALL. However, all passed away either due to relapse of disease or complications arising from treatment. DISCUSSION: The mechanism of lenalidomide associated SPMs is not well understood however its incidence is well documented. At least 13 cases of ALL (predominantly B-cell ALL) following Immunomodulator imide drugs (IMiDs) have been reported in literature. An analysis of a larger cohort of patients is required to determine causality of lenalidomide with sALL. However, benefits of maintenance lenalidomide in patients with MM outweighs the risk of developing SPMs. Albeit persistent pancytopenia on lenalidomide therapy should be evaluated with bone marrow biopsy since it could be caused by secondary B -cell ALL.