Real-World Data in Relapsed Refractory Myeloma Patients Treated with Pomalidomide, a Multicenter Turkish Experience

Introduction: Pomalidomide is a potent immunomodulatory drug (imid) with efficacy demonstrated in relapsed refractory multiple myeloma. In a phase 3 study, pomalidomide showed a benefit of PFS and OS over high dose dexamethasone, even in proteasome inhibitor and imid refractory patients.

In our country, Pomalidomide has recently gained approval in relapsed refractory setting in patients who were both refractory to a proteasome inhibitor and an immunomodulatory drug. Before this approval we were able to use pomalidomide as a single agent or as part of a combination approach via approval of health authority. Here we present our retrospective, multicenter, real life experience among patients with relapsed refractory myeloma and treated with pomalidomide.

Methods: 117 heavily pre-treated patients from 12 centers were retrospectively evaluated and the data among the use of pomalidomide, its efficacy and safety were analyzed.

Results: Median age of the patients included in the study was 68 (32-85) with a male ratio of 52.1%. ISS groups at diagnosis were as follows, stage 1 20.5%, stage 2 47% and stage 3 32.5%. 13 of 45 patients (28.9% ) were classified as high risk myeloma with an either del 17p or t(4,14) FISH positivity. Most of the patients were refractory to at least one proteasome inhibitor (96.6%), at least one imid (94%), or both (92.3%), even 27.4% were refractory to carfilzomib. Great majority (91.5%) of patients received pomalidomide as a single agent with concomitant corticosteroids. All patients included in the study were able to receive at least 2 cycles of pomalidomide. Median number of prior therapy line was 5 (2-11). Overall response rate, complete response + very good partial remission rate and partial remission rates were 35%, 11% and 24% respectively. Median duration of response was 4 months. Median progression free survival was 5.6 months and median overall survival was 8.4 months after initiation of pomalidomide. Overall survival was 4 months in patients who were not able to achieve at least stable disease. Hematological toxicity was the major toxicity which were reported at 77% of patients. Other major toxicities were as follows: fatigue 27.3%, pneumonia 20.5%, sepsis 12% (either neutropenic or non-neutropenic) and renal toxicity 6%.

Conclusions: Pomalidomide is an efficient option in advanced multiple myeloma. Even in a heavily pre-treated real-life patient group pomalidomide led to a significant overall response rate. Pomalidomide was well tolerated with manageable adverse events in this heavily pre-treated patient cohort. Most important side effects were hematologic and infectious. Proper infectious prophylaxis may decrease the rates of adverse events. Overall survival was relatively short after pomalidomide failure. Combination approaches with other novel agents may increase the response rates and prolong survival in such advanced relapsed/refractory patients.