Reversibility of Renal Failure in Newly Diagnosed Patients with Multiple Myeloma and the Role of Novel Agents.

Abstract 955

Renal impairment (RI) is a common complication of multiple myeloma (MM) and is associated with increased mortality. High dose dexamethasone-based regimens have been extensively used for the initial management of patients with MM presenting with RI. Recently, novel agent-based regimens have been introduced in the frontline management of MM. The purpose of our analysis was to assess the effect of novel agent-based regimens on the rate of RI improvement and compare their efficacy with conventional chemotherapy (CC) plus dexamethasone (Dexa) in newly diagnosed MM patients. Over the last decade, 82 patients with newly diagnosed MM and RI, defined as creatinine clearance (CrCI) <50ml/min, received frontline treatment in our Center. Patients were divided into three groups: group A: 28 patients who received CC plus Dexa-based regimens (VAD, VAD-like regimens, melphalan plus Dexa); group B: 38 patients who received IMiDs-based regimens (thalidomide or lenalidomide with high dose Dexa and/or cyclophosphamide or melphalan) and group C: 16 patients who received bortezomib-based regimens with Dexa. Renal complete response (RCR) was defined as a sustained increase of baseline CrCI to >60ml/min. Renal partial response (RPR) was defined as an increase of CrCI from<15 to 30-50ml/min. Renal minor response (RMR) was defined as sustained improvement of baseline CrCI of<15ml/min to 15-29 ml/min, or, if baseline CrCI was 15-29 ml/min, improvement to 30-59 ml/min. Patients in group B were older than those of groups A and C (p=0.01) while more patient in group C had light chain only MM than in groups A and B (p=0.04). There were no significant differences in the severity of RI, Bence Jones proteinuria, hypercalcemia or ISS stage among the three groups. Improvement of renal function, recorded as RMR or better, was achieved more frequently in patients treated with novel agents (group B: 87% and in group C: 94%) than in patients treated with CC plus Dexa-based regimens (64%, p=0.024). Among 9 patients who required renal dialysis 3 became independent of this procedure after treatment. We subsequently focused our analysis in major renal responses (RPR or RCR), because this endpoint is clinically more relevant. RCR was achieved in 43% of patients in group A, in 50% in group B and in 69% of patients in group C (p=0.2) and RCR+RPR rates were 50% and 57% and 81% for groups A, B and C respectively (p=0.1). Creatinine clearance <30 ml/min was associated with a significantly lower probability of RCR or RPR only in patients treated with CC plus Dexa- or with IMiDs-based regimens (p<0.01), but not in patients treated with bortezomib (p=0.529). The probability of RPR+RCR was similar for patients treated with IMiDs compared to CC plus Dexa-based regimens (p=0.619). In multivariate analysis bortezomib–based regimens (p=0.02, OR: 7, 95% CI 1.5-25) and CrCl>30 ml/min (p=0.002, OR: 6.1, 95% CI 2.5-22.5) were independently associated with a higher probability of RCR+RPR. The median time to RPR was similar for patients treated with IMiDs compared to CC plus Dexa-based regimens (2.2 months for Group A, 1.5 months for Group B, p=0.587) but it was significantly shorter for Group C (0.7 months, p=0.017). Other factors associated with a shorter time to ≥RPR included CrCl>30 ml/min (p=0.039) and age<75 (p=0.089). In multivariate analysis bortezomib–based regimens (p=0.004, OR: 3 95% CI 1.6-6.7) and CrCl>30 ml/min (p=0.006, OR: 2.5 95% CI 1.3-4.5) were independently associated with a shorter time to ≥RPR. In landmark analysis (time was one month in order to reduce bias due to early deaths), rapid improvement of renal function (≤1 month) was associated with a trend for a longer survival compared to patients who achieved renal response later (>1 month) (47 vs. 21 months, p=0.19). Myeloma response to treatment was 58%, 68% and 79% for the three treatment groups respectively and was associated with renal response (p=0.024), though less strongly with a major renal response (p=0.061). Our data indicate that novel agent-based regimens can improve renal function in most patients; furthermore bortezomib-based regimens improve renal function to a higher degree and significantly more rapidly than CC plus Dexa-based or IMiD-based regimens even in patients with severe renal impairment. We conclude that bortezomib-based regimens may be the preferred treatment for newly diagnosed myeloma patients who present with renal impairment.