Prognostic Risk Factor Evaluation in Patients With Relapsed or Refractory Multiple Myeloma Receiving Lenalidomide Treatment: Analysis of Renal Function by eGFR and of Additional Comorbidities by Comorbidity Appraisal

In patients with MM, RI remains associated with a poor prognosis, especially if it occurs at the time of MM diagnosis. The impact of various comorbidities in the era of novel agents is unknown and needs further investigation. We evaluated the safety, efficacy, and outcome of lenalidomide treatment in patients with relapsed/refractory MM and various comorbidities, including RI. Introduction: Renal impairment (RI) is a dreaded complication in multiple myeloma (MM) and has been associated with decreased progression-free survival (PFS) and overall survival (OS). Methods: Forty-five consecutive patients with MM received lenalidomide therapy combined with either dexamethasone or standard chemotherapy, with dose modification according to current guidelines. Comorbidity indices (hematopoietic cell transplantation specific comorbidity index [HCT-CI], Kaplan Feinstein [KF], and the Freiburg comorbidity index [FCI]) were analyzed and renal function was determined by estimated glomerular filtration rate (eGFR) before lenalidomide treatment and 1, 3, and 6 months after treatment. Results: The median patient age was 66 years. Pretreatment was substantial with 2 treatment lines in 71% of patients. Lenalidomide induced median PFS and OS of 13 and 25 months, respectively. The analysis of comorbidity scores identified only the FCI as significant, with different PFS for low-risk vs. high-risk patients of 20 vs. 9 months (p = .0036) and OS of not reached vs. 12.8 months (p < .0001), respectively. Although baseline renal function by serum creatinine evaluation appeared normal (median 1.0 mg/dL), mild RI was readily detectable by eGFR (median 83 mL/min/1.73 m2). When patients without RI were compared with those with mild, moderate, and severe RI, 1- and 2-year PFS rates were similar (hazard ratio [HR] with decreasing eGFR, 1.028;p = .6927). For OS, the HR of 1.192 indicated decreased survival probabilities with deteriorating eGFR (p = .0411), which was perceived by eGFR but not serum creatinine assessment (p = .2253). Conclusions: Lenalidomide was well tolerated in intensively pretreated and elderly MM patients, including those with RI. PFS was not significantly different in patients with decreasing eGFRs, albeit RI and other comorbidities remained significant for OS.