The MM-021 Trial Of Lenalidomide Plus Low-Dose Dexamethasone In Chinese Patients With Relapsed and Refractory Multiple Myeloma: Impact Of Prior Therapies On Efficacy and Safety
Authors: Jin Jie , Du Xin , Cai Zhen , Chen Fangping , Zhou Dao-bin , Yu Li , Li Xiao , Wu Depei , Meng Fanyi , Ai Huisheng , Wang Jianmin , Zhang Jingshan , Wortman-Vayn Honeylet , Mei Jay , Hou Jian 
Published: October 2019

Abstract

Background
The combination of lenalidomide (LEN) and low-dose dexamethasone (LoDEX) is approved in China for the treatment of multiple myeloma (MM) patients (pts) who have received at least 1 prior antimyeloma treatment. The MM-021 China registration study demonstrated the efficacy and safety of LEN + LoDEX (Rd). This sub-analysis investigated the impact of the number of prior antimyeloma therapies on treatment outcomes.

Methods
MM-021 was a phase 2, multicenter, single-arm, open-label study. Relapsed and refractory MM (RRMM) pts (aged ≥ 18 yrs) were given LEN (25 mg/day on days 1-21) and LoDEX (40 mg/day on days 1, 8, 15, and 22) in 28-day treatment cycles until disease progression or discontinuation. Pts included in the pharmacokinetics cohort did not receive DEX on day 1, cycle 1. All pts received thromboprophylaxis during the study. The primary end-point was best overall response rate (ORR), defined as the percentage of pts who achieved a best response of at least partial response. Secondary end-points included progression-free survival (PFS), time to progression (TTP), overall survival (OS), and safety. Data were analyzed according to the number of therapies that pts had received prior to study screening: 1-2, 3-4, or > 4.

Results
The analysis cut-off date was January 4, 2013, with a median follow-up of 17.6 mos. All pts in the intent-to-treat (ITT) population (N = 199) were included in the safety analysis, and 187 pts were included in the efficacy-evaluable (EE) population. At the cut-off date, 42 pts had completed treatment and 157 had discontinued. Overall, the median age of pts was 59.0 yrs (range 35-81) and 62.8% were male. The majority of pts had advanced disease (85.9% had Durie-Salmon stage III MM); 40.7% of pts (ITT population) had received > 4 prior anti-myeloma therapies; 33.2% had received 3-4, and 26.1% had received 1-2. Most pts had received prior treatment with thalidomide (THAL; 68.8%) or bortezomib (BORT; 63.8%) (Table 1). After a median treatment duration of 8.3 mos (range 0.9-24.8) or 9 treatment cycles (range 1-27), the ORR was 47.6% in the overall EE population, and highest in pts who had received 1-2 prior therapies (Table 2). Median OS, PFS, and TTP were longer in pts who had received 1-2 prior therapies compared with those who had received 3-4 and > 4 prior therapies, and compared with the overall EE population (Table 2). In the safety population, the most common grade 3-4 treatment-emergent adverse events (TEAEs) were anemia (26.1%), neutropenia (25.1%), thrombocytopenia (14.6%), pneumonia (13.1%), leukopenia (9.5%), and decreased neutrophil count (8.5%). In general, grade 3-4 TEAE rates were lower in pts who had received 1-2 prior therapies (60%), and comparable in pts who had received 3-4 (71%), > 4 prior therapies (75%), and the overall safety population (70%). There were 2 reports of grade 3-4 peripheral neuropathy. AEs resulted in discontinuation of LEN in 5.8% (n = 3), 10.6% (n = 7) and 9.9% (n = 8), of pts who had received 1-2, 3-4 and > 4 prior therapies, respectively.

Conclusion
Rd is an effective treatment option for Chinese RRMM pts who have relapsed after one or more prior therapies, including THAL and/or BORT. More robust efficacy and higher ORR was observed for Rd in patients who had received 1-2 prior therapies compared to those who had received additional lines of treatment. The tolerability of Rd was similar in heavily and less heavily pretreated pts. Discontinuations were infrequent, even in heavily pretreated pts who had received > 4 prior therapies.

Disclosures:
Zhang: Celgene Corporation: Employment, Equity Ownership. Wortman-Vayn:Celgene Corporation: Employment, Equity Ownership. Mei:Celgene: Employment, Equity Ownership. Hou:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; J & J: Honoraria, Membership on an entity's Board of Directors or advisory committees.