P-223: Bortezomib-Thalidomide-Dexamethasone (VTD) as salvage treatment in patients with Multiple Myeloma eligible for transplantation in the real world. Long-term follow-up

Abstract

<h3>Background</h3> Peru is a middle-income country with limited options to access to novel therapies in multiple myeloma (MM). Bortezomib has been introduced as salvage treatment a few years ago. In this setting, bortezomib, thalidomide, dexamethasone (VTD) became the standard salvage treatment for transplant-eligible patients <h3>Objectives</h3> To determine the response to treatment to VTD in patients with relapsed/refractory multiple myeloma eligible to transplant. To determine progression-free survival (PFS) and overall survival (OS) to VTD. <h3>Methods</h3> We retrospectively assessed the clinical efficacy and toxicity of VTD as salvage treatment in patients with relapsed/refractory MM eligible to autologous stem cell transplantation treated at Instituto Nacional de Enfermedades Neoplasicas in Lima, Peru, between January 2014 and December 2016. The treatment consisted of bortezomib 1.3 mg/m2 subcutaneously on days 1, 4, 8 and 11; thalidomide 100mg orally on days 1 through 21; dexamethasone 40mg orally on days 1, 2, 4, 5, 8, 9, 11, 12 for three-week cycles. Antithrombotic prophylaxis was based on acetylsalicylic acid. Prophylaxis against herpes zoster infection was with acyclovir 400mg twice a day, also trimethoprim/sulfamethoxazole was given each other day. <h3>Results</h3> Sixteen patients were found to fulfill the selection criteria. The median age was 52 (39-62), fifty-six percent (n=9) were male. International Staging System III disease was present in 75%.Ig G and IgA MM were 62.5% and 12.5% respectively. For VTd regimen the median number of treatment cycles delivered was four (range 2-5), totally 62 cycles. After a median follow-up of 19 months since patients received VTd (range 6-63), the overall response rate was 81%, stringent complete response (SCR) was 18.8% (n= 3), complete response 37.5%, very good partial response 12,5%. Seven out of 16 patients (43.8%) with VTD treatment who were candidates for transplantation finally were transplanted. Median PFS was 19 months (95% CI,12-NR), for the cohort who received SCT was the median PFS was 40 m (95% CI,16-NR), and for the cohort who did not undergo SCT was 14 m (95% CI, 6 - NR), however, this difference was statistically non-significant (p = 0.10). After a median follow-up of 41 months (range 7-141) since the diagnosis of MM, the median overall survival (OS) for the entire cohort was not reach (95% CI, 41– NR). For the cohort who received ASCT the median was not reached (95% CI, 41 - NR), and for the cohort who did not received was 49 months (95% CI, 22 - NR), however this difference was statistically non-significant (p = 0.20). 3-years OS was 86.7% (95%, CI, 56.4 –96.5), the 5-year OS was 66 m (95%, CI, 31.1 – 86.2). <h3>Conclusion</h3> VTD is an effective treatment in transplant-eligible patients with multiple myeloma who have relapsed after one previous therapy including thalidomide achieving high response rates and acceptable PFS and OS.