Therapeutic results of bortezomib multiple myeloma treatment: A monocentric study

Background: Multiple myeloma (MM) is an incurable pathology whose treatment has progressed over time. Bortezomib is now considered as a treatment that improves the prognosis of the disease in all stages. Given that Tunisia is a country with limited resources, the use of Bortezomib as a treatment for MM has only begun in 2016 as a part of a prospective protocol and could be administered only for high-risk patients (pts). Aims: Our study aims to report the therapeutic results of pts with MM from southern Tunisia treated with Bortezomib. Methods: It is a retrospective study over 4 years (2016-2019) which included young patients (<65 years old) with high-risk myeloma (ISS at 3, renal failure, and cytogenetic abnormalities with poor prognosis) and treated at the hematology department of Hedi Chaker Hospital Sfax, Tunisia with Bortezomib according to the 2016 national MM treatment guidelines. The treatment consists of 4 VTD courses every 21-day followed by an autograft. If autograft is not possible, consolidation at the base of 4 other CT courses should be received. Point-date is January 2021. We are interested in the response to treatment, overall survival (OS), and progression-free survival (PFS). Results: Thirty-eight patients were treated with VTD. The reason for treatment was an ISS score at 3, a renal failure, and a high-risk cytogenetic abnormality were recorded in respectively 28, 21, and 9 pts (2pts with17p del and 7pts with t (4,14)). Evaluation after 3 courses showed a complete remission (CR) in 8 pts(21%), a very good partial response( VGPR) in11 pts(28.9%), a partial response (PR) in 9 pts(23.6%), a minor response (MR) in 2 pts(5.26%), a stable disease (SD) in 2 pts(5.26%), and progression in 6 pts(15.7%). Autograft of hematopoietic stem cells was performed in10 pts. After autograft, CR, VGPR, PR rates were respectively 20%, 70%, and10%. Twenty-eight patients did not benefit from autograft either for early death, severe comorbidities or because of the limitation of hospitalization at the national bone marrow transplant center in Tunis because of Covid19 pandemic. Among un-grafted patients,17 have received a consolidation treatment, the rest either progressed (10.7%) or died (28.5%) before consolidation. The median survival was 26 months and two-year OS was 84.5%. OS was100% for autografted pts and 84% for those who received consolidation with significant difference (p=0.003). PFS was 61.6% at 24 months with PFS equal to 76% for autografted patients and 51.8% for those who received consolidation (p=0.021). Response after 3 courses influenced significantly the OS (p=0.027) in a multivariate analysis. Summary/Conclusion: Despite its high cost, Bortezomib has been a major breakthrough in the treatment of severe forms of MM. Although in our review we obtained an OS equal to 84.5% and an OR equal to 73.6% which remains lower than the results found in the literature (OS at 24 months better than 90% and OR varies between 85 and100%) which is explained by the use of Bortezomib only for high-risk patients and by the unavailability of autograft for all patients by its non-feasibility in our center, it is still better than results obtained by the old therapeutic protocol used in Tunisia based on DT, this prompts us to use this product for all patients and not only for high-risk ones and to generalize autograft.