P-181: Treatment outcome and prognostic factors of newly diagnosed Multiple Myeloma receiving Bortezomib-based induction in Hong Kong: an analysis of 448 patients

Background Autologous stem cell transplant (ASCT) is the standard of care for eligible patients with newly diagnosed multiple myeloma (NDMM). In Hong Kong, NDMM received bortezomib-based triplet induction. NDMM ≤65 years of age were considered transplant-eligible (TE), and >65 years transplant-ineligible (TIE). Therefore, upfront ASCT is offered to all TE patients ≤65 years, unless considered medically unfit (TE-unfit) or ASCT refused (TE-refused). The outcome and risk factors were analysed herein. Data was retrieved from the HKSOM database from 2006 to Jan 2021 for 448 NDMM patients treated with bortezomib-based induction therapy, with bortezomib-based triplet in the majority (n=425; 94.9% were triplets). For the entire cohort, apart from being TIE, additional adverse factors for both event free survival (EFS) and overall survival (OS) male gender, advance ISS, R-ISS stage 3, high LDH, failure of post- induction CR, and high-risk FISH. Multivariate analysis excluding high-risk cytogenetics (incomplete data in many) showed that male gender (p=0.026), advance ISS (p=0.000357), high LDH (p=0.000129), CR induction (p=0.003) and ASCT (p=0.001) were negative predictors for OS. In the TE group, upfront ASCT were conducted in 252 (76.1%). Among the TE patients, ASCT was not performed in 63, due to being medically unfit (TE-unfit) (N=41; 12.4%) or patient refusal (TE-refusal) (N=22; 6.6%). Compared with transplanted MM, failure to undergo ASCT rendered a much inferior OS in TE-unfit and TE-refusal (p=1.03×10-8) and EFS (p=0.000043), with survivals comparable to that of TIE patients (median OS 48 months p=0.576, median EFS 31 months p=0.614). Among TE patients who had undergone ASCT, adverse risk factors for OS and EFS included advance ISS (p=0.000293), RISS stage 3 (p=8.5×10-9) and high LDH (p=0.000019). Multivariate analysis excluding high-risk cytogenetics (incomplete data in many) showed age (p=0.012), ISS (p=0.000353) and high LDH (p=0.002) were adverse predictors OS. Post-induction CR predicted superior EFS (median 83 months vs 45 months p=0.006) but not OS. The presence of high-risk FISH (median OS 131 months vs 86 months p=0.022) negatively impacted on OS despite ASCT. Our data reaffirmed the favourable impact of ASCT Conclustion Among transplanted patients, adverse risk factors for both OS and EFS included ISS, LDH, HR FISH and post-induction CR status. Moreover, while ASCT was offered to those MM patients ≤65 years, advanced age remained an adverse risk factor. Importantly, among TE patients, refusal of ASCT rendered an inferior EFS and OS comparable to TIE MM that requires due consideration when providing counselling on ASCT in TE MM.