Risk of Progression and Survival in Newly Diagnosed Multiple Myeloma Patients Non-Responsive to Bortezomib-Based Induction Therapy: an Observational Multicenter International Study
Authors: Cohen Yael C , Joffe Erel , Benyamini Noam , Dimopoulos Meletios A. , Trestman Svetlana , Held Viki , Avivi Irit , Kastritis Efstathios 
Published: October 2019

Abstract
INTRODUCTION
Botezomib-based induction is widely used and highly effective for the treatment of patients with newly diagnosed multiple myeloma (NDMM), with an overall response rate (ORR) of 75-80%. However, the outcomes of patients who fail to respond to this treatment remain unclear. The goal of this study was to investigate the outcome of patients with NDMM who failed to respond to bortezomib-based induction as compared to induction-responsive patients.
METHODS
We reviewed consecutive patients with NDMM between 1-JAN-2007 and 31-JAN-2014 in three participating centers in Greece and Israel. Inclusion criteria were measurable disease and an induction regimen containing bortezomib in combination with alkylators and/or corticosteroids. Patients who failed to achieve at least partial response in accordance with IMWG criteria after 4 cycles of therapy were classified as non-responsive and their baseline characteristics, next treatment, overall survival and progression following second-line treatment (2ndPFS) were assessed and compared to responsive patients. 2ndPFS was defined as the time from 2nd line treatment to disease progression, death or censoring. In the non-responsive group we limited this analysis to patients advancing to 2nd line within six months of initiation of induction.
RESULTS
Two hundred and ninety five patients met inclusion criteria and 74 (25%) were non-responsive to bortezomib-containing induction. Non-responsive patients were older, more anemic and had more often ISS-3, del17p and ECOG performance status 2-4 (table 1). Notably, these patients received less often a bi-weekly bortezomib schedule, a triple-drug regimen and high dose melphalan treatment at first line.
Of the non-responsive patients 57% (n=42) received salvage treatment immediately following induction non-response, with an ORR of 59% (25/42); 12/31(39%) of those treated with salvage 2nd line and 13/15(87%) of those who underwent HDM at first line, responded.
Failure to respond to bortezomib induction was associated with increased mortality (HR 5.06, 95% CI 2.80 – 9.16) (Fig. a), which remained significant in multivariate analysis. One- and 3-years OS in responsive vs. non-responsive patients were 97% vs 76% and 88% vs 53%, respectively (p<0.0001).
2ndPFS in patients who received salvage second line therapy immediately following induction failure was similar to that measured in bortezomib-responsive patients receiving 2nd-line therapy for disease progression, approaching 14 months. However, survival from time of salvage 2nd-line treatment was significantly lower among patients non-responsive to bortezomib-based induction compared to that measured in responsive patients (25 months vs. not reached, respectively, p=0.024; Fig. b).
CONCLUSIONS
Failure to respond to a bortezomib-based induction was found to be an independent risk factor for mortality. Despite the non-inferior 2ndPFS reported in these patients as compared with their bortezomib-responsive counterparts, survival remained significantly inferior. Possibly this difference is because non-responsive patients are less likely to respond to further proteasome inhibitor therapy at following relapses. Randomized controlled trials are needed to test whether intensification of induction and/or of further treatment may improve the poor prognosis of patients who fail to respond to bortezomib-based induction.
Table 1: All patients n = 295 Induction non-responsive n = 74 Induction - responsive n =221 P value Demographic Median Age (yrs) 62.0 66.8 61.0 0.004 Gender Male Female 148 (50%) 147 (50%) 42 (55%) 33 (45%) 107 (48%) 114 (52%) 0.347 Patient / Disease ECOG 0-1 2-4 182 (63%) 107 (37%) 33 (45%) 40 (55%) 149 (69%) 67 (31%) <0.0001 ISS I II III 74 (28%) 95 (36%) 95 (36%) 9 (14%) 20 (33%) 33 (53%) 65 (32%) 75 (37%) 62 (31%) 0.002 High risk Cytogenietics Del17p High risk (%) Elevated LDH (%) Extramedullary disease (%) Hb≤ 10 gr% Creatinine > 2mg% 23 (14%) 69 (34%) 66 (27%) 23 (9.5%) 114 (43%) 64 (23%) 10 (26%) 13 (28%) 21 (36%) 5 (8.1%) 35 (54%) 20 (30%) 13 (10%) 56 (36%) 45 (24%) 18 (9.7%) 79 (39) 44 (21%) 0.031 0.297 0.091 0.805 0.044 0.094 Therapy Induction regimen VCD Vd VMP PAD 204 (69%) 49 (17%) 11 (4%) 19 (6%) 52 (57%) 18 (24%) 3 (4%) 4 (5%) 162 (73%) 31 (14%) 8 (4%) 15 (7%) 0.007 Any triplet 243 (82%) 55 (74%) 188 (85%) 0.051 Bortezomib schedule Bi-weekly Weekly 239 (81%) 56 (19%) 52 (70%) 22 (30%) 187 (85%) 34 (15%) 0.010 HDM at first line 143 (48%) 15 (20%) 128 (58%) <0.0001
Figure 1 Figure 1.

Disclosures
Dimopoulos: Celgene: Consultancy, Honoraria.