LAUSR

Background Currently, the recommended dose of nivolumab for patients with relapsed or refractory classical Hodgkin lymphoma (r/r сHL) is 3 mg/kg. Nevertheless, published clinical cases indicate the possible efficacy of lower doses of nivolumab. Moreover, experimental studies provided the rationale for possible reduction of nivolumab dose in patients with solid tumors (Agrawal et al. 2016). The presented data creates prerequisites for studying the lower nivolumab doses efficacy and safety in the r/r cHL therapy. Patients and Methods This study included 42 patients (14 male/28 female) with r/r cHL who were treated with nivolumab 40 mg every 2 weeks. The median age of patients was 36 (22-53) years. The median number of prior therapy lines was 4 (2-7). Prior treatment contained high dose chemotherapy with ASCT in 9 pts (21%), brentuximab vedotin in 14 pts (33%) and allo-HSCT in 1 pt (2%). Four pts (9,5%) had the partial response (PR) and the remaining 38 pts (90,5%) had the disease progression (PD) at the moment of nivolumab initiation. B-symptoms were present in 23 pts (55%), ECOG status was grade 0-I in 25 pts (59,5%), grade II in 12 pts (29%), grade III in 4 pts (9,5%) and grade IV in 1 pt (2%). The primary endpoint was the overall response rate (ORR) determined by positron-emission tomography/computed tomography (PET/CT) using LYRIC criteria every 3 months. Key secondary endpoints included progression-free survival (PFS) and overall survival (OS). Adverse events (AE) were evaluated according to CTCAE 4.03. The patient group characteristics were evaluated using descriptive statistics methods, the survival analysis was performed using Kaplan-Meyer method (SPSS Statistics v.17). Results The median number of nivolumab cycles was 24 (2-38). The response was evaluated in 41 out of 42 pts. The ORR was 66%. The best response included complete response (CR) in 39%, PR in 27%, stable disease in 5%, PD in 2%, indeterminate response (IR) in 27% of pts. With a median follow-up of 27,5 mo (11,3-34,5) 41 pts (97,6%) were alive, the median OS was not reached. The 2-year PFS was 44,5% (95% CI, 28,2-59,6) The nivolumab therapy was discontinued in 39 pts (93%) due to scheduled discontinuation in 14 pts (33%), PD in 13 pts (31%), grade 3-4 AE in 2 pts (5%), change of therapy because of insufficient response in 6 pts (14%) and other reasons in 4 pts (10%). The progression of disease during nivolumab therapy was present in 14 (33%) pts and after nivolumab discontinuation in 6 (14%) pts. After disease progression 30 pts (71%) were retreated with nivolumab monotherapy or in combination with chemotherapy. The median time to additional therapy was 14,5 mo (4,2 -32,9). The adverse events of any severity were observed in 30 pts (71%). Grade 3 or higher AE were present in 4 pts (9,5%), including grade 3 arthralgia, grade 3 anemia, grade 4 pneumonia and pneumonitis, grade 4 increased level of alanine aminotransferase and grade 5 MDS in 1 pt. A significant reduction of PD1+CD3+ cell population of peripheral blood lymphocytes was observed after first nivolumab cycle (median 0.7% (0-1.7) versus 33% (15.7-80.1) before therapy initiation, p = 0.02, Wilcoxon signed-rank test). Conclusion Our study demonstrated the efficacy and safety of nivolumab 40 mg therapy. The presented results are comparable to previously published data of nivolumab 3 mg/kg therapy in patients with r/r cHL. Thus, this creates a basis for further direct comparative study of nivolumab efficacy in different doses No relevant conflicts of interest to declare.