Similar Efficacy of Thalidomide-Based and Bortezomib-Based Regimens In the First Relapse of 209 Multiple Myeloma Patients Previously Untreated with Novel Drugs
Authors: Krejci Marta , Gregora Evzen , Spicka Ivan , Scudla Vlastimil , Straub Jan , Minarik Jiri , Adam Zdenek , Krivanova Andrea , Pour Ludek , Zahradova Lenka , Mayer Jiri , Hajek Roman 
Published: October 2019

Abstract
Abstract 5027

Background:
Novel agents, such as immunomodulatory drugs and proteasome inhibitors, have substantially changed the treatment paradigm of multiple myeloma (MM). Until now, many combination regimens with novel drugs have been published, but different regimens have rarely been compared in the treatment of the first relapse of MM.

Aims:
In this report, we describe the outcome of a cohort of 209 patients (pts) with the first relapse of MM treated with thalidomide-based and bortezomib-based regimens with aims to compare the efficacy of these therapies.

Methods:
Eighty-two percent of pts (171/209) had stage III according to Durie-Salmon (DS), 17% (35/209) II and 1% (3/209) I, clinical stages according to International Staging System (ISS) were the following: stage 1 in 46% of pts (92/199), stage 2 in 29% of pts (57/199) and stage 3 in 25% of pts (50/199). Renal insufficiency was presented in 14% of pts (30/209). Median age was 64 years (range: 34–84). Thalidomide-based (T) regimens were used in 105 pts; thalidomide + alkylating agent + dexamethasone: 91 cases (87%), thalidomide + dexamethasone: 5 cases (5%), alone thalidomide: 9 cases (8%). The daily dose of thalidomide was 100–200 mg. Bortezomib-based (B) regimens were used in 106 pts; bortezomib + alkylating agent + dexamethasone: 58 cases (55%), bortezomib+alkylating agent or dexamethasone: 40 cases (38%), alone bortezomib: 8 cases (7%). Bortezomib was used in standard dose 1.3 mg/m2 intravenously on days 1, 4, 8, 15. The cycle repeated on day 21–28 for up to 8 cycles or until progression. Median of T and B treament cycles was 5, range 1–8. No statistically significant differences were observed between the T and B groups in baseline clinical parameters including age, clinical stages according to ISS and DS staging systems, the type of M-protein and presence of renal impairment. The first-line therapy was comparable for both T and B groups and it is not include novel agents. Median follow-up from start of treatment was 19.5 months (range 0.9–53.3).

Results:
In T group, overall response rate (ORR) was 51% (51/100), 11% of pts (11/100) achieved the complete response (CR), 16% of pts (16/100) were in very good partial response (VGPR), 24% of pts (24/100) in partial response (PR), 9% of pts (9/100) had minimal response (MR) or stable disease (SD) and 40% of pts (40/100) had progression of disease. Median time to progression (TTP) from the start of relapse treatment was 13.1 months, median overall survival (OS) was 30.4 months. Patients in T group with ORR had significantly longer OS than pts without ORR (median 46.1 months versus 22.1 months; p = 0.005). Clinical stages according to ISS in T group significantly influenced both TTP (p = 0.004) and OS (p = 0.001).
In B group, ORR was 50% (34/68), 9% of pts (6/68) were in CR, 16% of pts (11/68) were in VGPR, 25% of pts (17/68) in PR, 17% of pts (12/68) had MR or SD and 32% of pts (22/68) had progression of disease. Median TTP from start of relapse treatment was 16.7 months, median OS was 37.2 months. Patients in B group with ORR had significantly longer OS than pts without ORR (median 50.1 months versus 21.2 months; p = 0.002). Clinical stages according to ISS in B group did not significantly influence TTP (p = 0.483) and OS (p = 0.207).
Age, renal impairment and type of M-protein did not significantly affect TTP and OS in both T and B groups.

Conclusion:
The thalidomide-based and bortezomib-based regimens are similarly effective in treatment of the first relapse MM with ORR 50–51%. No statistically significance differences were observed between thalidomide-based and bortezomib-based regimens in terms of TTP (p = 0.207) and OS from the start of relapse treatment (p = 0.889).

Disclosures:
No relevant conflicts of interest to declare.