The Impact of Induction Regimen Choice on Transplant Outcome and Survival in Newly Diagnosed Multiple Myeloma in the Era of Novel Agents

Background

Induction with novel agents, including proteasome inhibitors and immunomodulators, prior to autologous stem cell transplantation (ASCT) is the standard of care frontline treatment of transplant-eligible patients with multiple myeloma (MM). Common novel agent-based induction regimens include three drug combinations with a backbone of bortezomib (V), thalidomide (T) and/or lenalidomide (R). There is limited information on the comparative efficacy of novel regimens used as part of initial therapy prior to an ASCT in terms of overall survival (OS). To address this question, we retrospectively analyzed 1096 consecutive patients undergoing ASCT for MM at Mayo Clinic.

Methods

Study patients included those who underwent first transplant within 12 months of diagnosis, did not receive more than one induction regimen, did not relapse prior to transplant and did not receive treatment for smoldering MM in the past. Baseline characteristics, response rates and survival data were extracted from an electronic medical record and statistical analysis was done using JMP 10.0.0 (SAS Institute Inc.). Choice of induction regimen was almost exclusively made by the referring physician.

Results

Median age at diagnosis was 60.3 years (Interquartile range 53.9-65.9). ISS staging at diagnosis was available for 49.7% of patients, of which, 34.2%, 39.3% and 26.5% of patients had ISS stage 1, 2 and 3 disease, respectively. Estimated median follow up was 65.6 months (95% CI 58.3-73.3). Baseline characteristics of patients by initial treatment have been summarized in table 1. Major subgroups by induction therapy included patients receiving Cy-Bor-d (n=193, 17.6%), Vd (n=64, 5.83%), Rd (n=253, 23.1%), VRd (n=126, 34.6%), Td (n=157, 14.3%) and VAD or dexamethasone alone as the non-novel agent comparator group (n=229, 20.9%). Median overall survival (OS) was significantly different between novel agent-based and conventional regimens (Log-rank test; p=0.0029), which were 102.7 months (95% CI, 95.2-112.2) and 78.8 months (95% CI, 67.8-92.6) respectively. Median OS with each regimen is shown in table 1. Among novel agent-based regimens, there was no significant difference in median OS, except Td, which was inferior to Rd (HR 1.62; 95% CI 1.17-2.24).

Conclusion

We cannot demonstrate with overall survival as an endpoint that the doublets of Vd and Rd are inferior to VRd or Cy-bor-d. There were insufficient patients treated with VTd to be included. Our study shows that the choice of novel induction regimen prior to ASCT does not affect survival (with the exception of Td being inferior to Rd), reflecting the wide array of effective salvage options. However, further prospective randomized clinical trials comparing these regimens are required to validate these findings.

 

Baseline characteristics and survival	Cy-Bor-d (n=193)	Vd (n=64)	Rd (n=253)	VRd (n=126)	Td (n=157)	VAD or Dex (n=229)	p-value
Median age	61.9	62.15	60.8	60.8	59.3	58.5	0.0041
Sex (percent males)	56.48	57.81	56.92	61.91	57.96	59.82	0.9271
ISS at diagnosis	1:24.82% 2:40.69% 3:34.48%	1:29.73% 2:24.32% 3:45.94%	1:40% 2:43.78% 3:16.22%	1:41.76% 2:34.06% 3:24.18%	1:28% 2:36% 3:36%	1:20% 2:60% 3:20%	0.0005
Median follow-up (95% CI)	20.3 (17.1-22.7)	49.5 (44.7-55.7)	59 (54.5-67)	26.9 (22.8-30.7)	126.7 (120.2-132.9)	143.4 (132.5-152.6)	<0.0001
Median OS	Not reached (Estimated 5 year OS rate 75%)	97.2 months (95% CI, 66.6-NR)	112 months (95% CI, 97.4-124.3)	Not reached (Estimated 5-year OS rate 77%)	81.1 months (95% CI, 59.1-99.1)	78.8 months (95% CI, 67.8-92.6)	0.0019

Table 1. Baseline characteristics and overall survival

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