A Phase II Open-Label, Multi-Center Study of Anti-CCR4 Monoclonal Antibody Mogamulizumab (KW-0761) in Patients with Previously Treated Peripheral T-Cell Lymphoma(PTCL)

Background

CC chemokine receptor 4 (CCR4) is the receptor for macrophage-derived chemokine (MDC/CCL22) and thymus activation-regulated chemokine (TARC/CCL17). CCR4 is expressed on tumour cells in approximately 30-65% of patients with PTCL (Ogura, 2014). PTCL-NOS patients who are CCR4 positive have been reported to have a poorer prognosis compared to CCR4 negative patients (Ishida T CCR 2004). Mogamulizumab (KW-0761) is a defucosylated, humanized, IgG1 Mab with enhanced antibody dependent cellular cytotoxicity, that binds to CCR4. Mogamulizumab was evaluated in both phase 1 and 2 trials in Japanese patients. A phase II trial in PTCL and cutaneous T-cell lymphoma (CTCL) patients (Ogura, 2014) reported an overall response rate (ORR) of 35% in patients who relapsed after last systemic therapy (ORR was 34% in PTCL), leading to its approval in Japan in patients with previously treated CTCL and PTCL, in addition to its first indication, previously treated adult T-cell leukemia-lymphoma. Here we report the preliminary results of a European phase II trial of mogamulizumab in patients with relapsed/refractory PTCL.

Methods

A multi-center phase II study of mogamulizumab monotherapy was conducted to determine efficacy, safety and immunogenicity in patients with CCR4+ PTCL. The primary endpoint was ORR and secondary endpoints included duration of response, progression-free survival (PFS) and overall survival (OS). At least 34 evaluable patients were needed to detect a significant improvement over 15% assuming 80% power and a 0.0240 alpha significance level (assumes 35% ORR for alternative). Patients received mogamulizumab once weekly for 4 weeks and subsequently once every 2 weeks until progressive disease (PD) or unacceptable toxicity at a dose of 1.0 mg/kg. Responses were assessed every 8 weeks according to IWG criteria (Cheson et al 2007).

Results

Based on a preliminary analysis of the data, a total of 38 patients received at least one administration of mogamulizumab and were evaluable for safety analysis; (Male/female 23/15 ;Median age 58.5 years (range 19-87)). Three patients are still ongoing in the study (1 complete response (CR) and 2 stable disease (SD)). ECOG performance status at baseline was 0 (32%); 1 (29%); 2 (39%) and 92% of patients had stage III (32%) or IV (61%) disease. The median number of prior treatments was 2 (range 1-8). Only 17 patients (49%) responded to the last treatment administered prior to study entry. The median number of mogamulizumab administrations was 6 (range 1-32). The majority of adverse events (AEs) were CTCAE grade 1-2. Skin rash related to drug was observed in 32% of patients (12/38) and related AEs > grade 3 occurred in 32% (12) of patients. Infusion related reactions occurred in 3 patients (2 were CTCAE grade 2 and 1 was grade 3). Thirty-five patients were evaluable for efficacy. The ORR rate was 11% and the stable disease rate was 34% with a SD or better rate of 46%. The response by histological subtype is specified in the table below. The median duration of response (including SD) is 2.9 months. The median PFS is 2.1 months. Two patients (ALCL-ALK-neg and PTCL-NOS) proceeded to allogeneic SCT. Although the ORR in this study was less than seen in the Japanese study, the PFS was comparable. There were differences in patient population/study conduct between the Japanese study and this study, respectively, which included: inclusion of only relapsed patients (100% vs 49%), ECOG PS 2 (0% vs 39%) and response assessments (after 4 and 8 weeks versus 8 weekly from week 8).

Conclusions

Based on preliminary data, mogamulizumab demonstrates a SD or better rate of 46% and an ORR of 11% with an acceptable safety profile in this phase II study of heavily pre-treated relapsed/refractory PTCL patients.

*One patient had CR by CT scan but did not have bone marrow done for confirmation of CR