Association of thrombocytopenia with disease burden, high-risk cytogenetics, and survival in newly diagnosed multiple myeloma patients treated with novel therapies

Background The effect of thrombocytopenia has not been studied in the era of novel treatments in multiple myeloma (MM) Objective To evaluate the clinical characteristics and outcomes in MM patients presenting with thrombocytopenia. Materials Newly diagnosed MM patients between 2008 and 2018 who received at least 2 novel agents at induction. Thrombocytopenia was defined as a platelet count of less than < 150,000/mm3. Results A total of 648 patients were identified. Thrombocytopenia was found in 120 patients (18.5%). Baseline disease characteristics associated with higher rates of thrombocytopenia at baseline included IgA myeloma, p<0.01, ISS 3 vs. 1 or 2, p<0.01, R-ISS 3 vs. 1 or 2, p<0.01, renal failure (CrCl<30 ml/min), p<0.01, hypercalcemia (Ca>11.5 mg/dL), p<0.01, elevated LDH, p<0.03, anemia (Hb<10 g/dL), p<0.01, higher serum monoclonal protein, p<0.02, and >60% plasma cells in the bone marrow, p<0.01. Thrombocytopenia was more prevalent across patients with t(4;14) and t(14;16), but was not associated with an overall high-risk FISH classification. Median OS was significantly lower among patients with thrombocytopenia (64.4 vs. 145.0 months, p<0.01). In multivariable Cox regression, thrombocytopenia was associated with mortality (HR= 2.45, 95% CI; 1.7 – 3.6) independently of age, sex, high-risk FISH, ISS stage, response at induction, percentage of plasma cells in the BM, and anemia. Conclusion We found that thrombocytopenia was seen among one-fifth of MM patients and was more common in patients with [t(4;14) and t(14;16)]. Thrombocytopenia had an independent association with worse survival. Micro-abstract In this analysis of myeloma patients treated with novel agents, 18.5% presented with thrombocytopenia, which was associated with other high-risk disease indicators and genetic abnormalities. Thrombocytopenia at diagnosis independently predicted shorter survival, underlining the importance of myeloma prognostication, even in the era of novel agents.