Bortezomib Versus Non-Bortezomib Based Initial Treatment for Transplant Ineligible Patients with Light Chain Amyloidosis

Introduction: Chemotherapeutic options for patients with systemic light chain amyloidosis (AL) who are not transplant candidates include bortezomib based therapy, melphalan with dexamethasone, and less commonly, immunomodulatory drugs (IMiDs). However, prospective clinical trial data comparing these regimens are lacking. This study aims to compare efficacy of bortezomib-based treatment to other therapies. Methods: All patients with AL seen within 90 days of diagnosis at our institution over a 10-year period (2006 to 2015) who did not undergo a stem cell transplant were identified from our institutional database. Data pertaining to demographics, diagnosis, treatment and follow-up were extracted from electronic medical records. Analyses were carried out by chi-square and Fisher9s exact test for categorical variables and Kruskal-Wallis and Wilcoxon rank sum test for ordinal and continuous variables. Progression free survival (PFS) is defined as time to death, progression requiring treatment change or relapse requiring re-institution of treatment. PFS and overall survival was analyzed via the Kaplan-Meier method. Results: Seven hundred and twenty five patients met the inclusion criteria, of which 38% (n=275) received bortezomib containing regimens and 62% (n=450) received non-bortezomib based therapies. Bortezomib was used with dexamethasone in 24% (n=67) patients; and with other drugs, most commonly cyclophosphamide, in 76% (n=208) patients. Non-bortezomib treatment regimens included melphalan-based treatment in the majority (92%, n=414) followed by IMiDs with steroids and other drugs (8%, n=36). Baseline variables similar in both groups and their distribution in the entire cohort was as follows: gender distribution (63.3% males, n=459), median age of diagnosis (66.3 years, range 32.2 to 93.6), type of involved free light chain (FLC) (lambda 73%, n=523) and median plasma cell burden (10%, range 0 to 91). Median difference between the involved and uninvolved free light chain (dFLC) was higher in the bortezomib group (29 mg/dL vs. 23 mg/dL; p=0.017). There was no difference in organ involvement. In the bortezomib group, organ involvement was as follows: cardiac (81%, n=219), renal (62%, n=168) and hepatic (18%, n=48). In the non-bortezomib group, the rates of organ involvement were similar: cardiac (78%, n=346), renal (57%, n=247) and hepatic (19%, n=85). Median duration of first line treatment was similar in the 2 groups, with 178 days in the bortezomib cohort and 187 days in the non-bortezomib cohort. Response rates are illustrated in Table 1. Rates of very good partial response (VGPR) or better response were higher in the bortezomib group (64 % vs. 54%, p=0.0002). Patients treated with bortezomib achieved VGPR faster with higher rates of VGPR or better response seen at 3 months (48% vs. 27%, p Relapse or progression requiring change in therapy was more common in patients treated with non-bortezomib based therapy (38%, n=143/372) compared to bortezomib-based treatment (28%, n=67/236); p =0.01). However, no difference in overall survival was observed in patients treated with bortezomib (2.2 years; 95% confidence interval (CI): 1.7 to 3.3) vs. non-bortezomib therapies (1.7 years; 95% CI: 1.3 to 2.5). Conclusion: Treatment with bortezomib-based regimens results in a deeper response including higher rates of early VGPR at 3 and 6 months from starting therapy. Moreover, these patients achieve cardiac response faster and have lower rate of relapse. However, no difference in overall survival was seen, which may be explained by subsequent use of bortezomib-based therapies in this population. Disclosures Dispenzieri:Celgene: Research Funding; Alnylam: Research Funding; pfizer: Research Funding; Jannsen: Research Funding; Takeda: Membership on an entity9s Board of Directors or advisory committees, Research Funding; GSK: Membership on an entity9s Board of Directors or advisory committees; Prothena: Membership on an entity9s Board of Directors or advisory committees. Kumar:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Onyx: Consultancy, Research Funding; AbbVie: Research Funding; Janssen: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; BMS: Consultancy; Skyline: Honoraria, Membership on an entity9s Board of Directors or advisory committees; Array BioPharma: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Kesios: Consultancy; Glycomimetics: Consultancy.