Bortezomib-Doxorubicin-Dexamethasone (BDD) for Reversal of Acute Light Chain Induced Renal Failure (ARF) in Multiple Myeloma (MM). Results from a Phase II Study

Acute light chain induced renal failure (ARF) is a severe complication of progressive MM, leading to permanent renal dysfunction and dependence on chronic hemodialysis in a substantial proportion of patients (pts). Reversal of kidney failure can only be achieved by fast and substantial suppression of pathogenic light-chains with effective anti-MM therapy. Bortezomib in combination with doxorubicin and dexamethasone has been shown to be highly effective in newly diagnosed pts. In addition, bortezomib is well tolerated in pts with reduced glomerular filtration rate (GFR) and its half life is independent of renal function. In this study we aimed to evaluate the efficacy of the BDD regimen in restoring renal function and in achieving tumor control in pts with light chain-induced renal failure. Up to now 67 of 70 planned pts have been enrolled. Documentation is available for 55 pts for intent to treat analysis and for 47 evaluable for renal and tumor response (age: median 66 years, range 41–79 years, ISS stage I: 2%, II: 13%, III: 85%. 37 (79%) of pts presented with de novo MM, and 10 (21%) with progressive disease; baseline median GFR 19.8 ml/min (range 3.7–49.9ml/min). ARF was defined in newly diagnosed pts as reduction of GFR to <50ml/min due to MM nephropathy, and in previously treated pts with signs of tumor progression and a GFR of ≥60ml/min within the last 4 weeks before enrolment as a reduction of GFR by >25% to <50ml/min. Treatment regimen: Bortezomib (1.3mg/m², d 1, 4, 8, 11 until the first safety analysis; thereafter 1.0mg/m² d 1, 4, 8, 11), doxorubicin (9mg/m², d 1, 4, 8, 11 until first safety analysis; thereafter 9mg/m², d 1 and 4) and dexamethasone 40mg (d 1, 4, 8, 11). Cycles were repeated every 21 days. 47 pts have completed at least 2 cycles and are evaluable for response as yet. 23 pts achieved CR/nCR (50%), 3 (6%) VGPR, 6 (13%) PR and 5 (11%) MR (CR-MR: 90%). Median time to response was 108 days. Median GFR increased from 19.8 ml/min (range: 3.7 – 49.9 ml/min) to 46.1ml/min (range 6.7 – 106 ml/min). Improvement of GFR correlated weakly with tumor response. In 26 pts with CR/nCR/VGPR, median GFR increased to 62 ml/min (10–106 ml/min). Best median GFR was 25 ml/min (11 – 106 ml/min) in 11 pts with PR/MR, and 22 ml/min (7 – 51 ml/min) in 10 pts with SD/PD. When renal response was defined either as complete (CR^renal: GFR≥60 ml/min), partial (PR^renal: increase from GFR <15 ml/min to 30–59 ml/min), or minor (MR^renal: increase in GFR either from < 15 ml/min to 15–29 ml/min or from 15–29 ml/min to 30–59 ml/min), a total of 15 (32%), and 14 (30%) pts achieved a CR^renal, or a PR/MR^renal, respectively, yielding an ORR^renal in 29 (62%) of pts (Table 1). Three of 8 dialysis dependent pts became dialysis independent.

Table 1

Overall survival (OS) was 72% @ 2 years in the intent to treat and 78% @ 2 years in the evaluable population. OS was 76% @ 2 years in pts without CR^renal, and 86% in pts with CR^renal. Leucopenia, thrombopenia, and anemia of grade 3&4 were seen in 15%, 6% and 6%, respectively. Other common grade 3&4 toxicities were infection (4%), nausea/vomiting (6%), weakness/fatigue (11%) and polyneuropathy (8%). In conclusion, the BDD regimen resulted in high tumor (CR/VGPR 56%, ORR: 90%) and renal response rates (CR^renal 32%, ORR^renal 62%). Improvement of renal function was more often seen in pts with significant tumor response and CR^renal was more likely in pts with less severe renal impairment. Treatment was well tolerated after dose adjustment.