First Interim Efficacy and Safety Analysis of an International Phase III Randomized Trial in Newly Diagnosed Systemic Peripheral T-Cell Lymphoma Treated with Chemotherapy with or without Alemtuzumab and Consolidated by High Dose Therapy

The ACT trial (ACT-1, younger patients aged 18–60 yrs and ACT-2, elderly patients aged >60 yrs) is the first international randomized phase III trial in newly diagnosed primary systemic peripheral T-cell lymphoma (PTCL). It tests, in both younger and elderly patients, the efficacy of the addition of alemtuzumab (ALZ) to 6 courses of bi-weekly CHOP followed, only in younger patients (ACT-1), by high-dose therapy with autologous stem cell rescue. A dose reduction amendment tapering the cumulative ALZ dose from 360 mg (30 mg on days 1 and 2 of CHOP courses 1–6) to 120 mg (30 mg on day 1 of CHOP courses 1–4), respectively, was introduced early on due to two cases of systemic fungal infection (Blood 2011,118;4110). To date, the trial has accrued a total of 186 patients (ACT-1 n=98; ACT-2 n=88).

Here, we present the results from the first interim efficacy and safety analysis of the ACT-1 trial based on the first 68 randomized patients.

Of the 68 patients, 63 had a complete set of treatment data. The median follow-up was 15 months (range 0.5–42 months). Thirty-two patients belonged to the experimental arm (exp) and 31 to the standard arm (std). Of the 32 patients treated according to exp, 4 received the higher dose of ALZ and 28 the lower. Treatment arms were well balanced with regard to main prognostic features such as age (std: median 53 yrs, range 21–60 yrs; exp: median 50 yrs, range 22–64 yrs; p=0.705), IPI subgroups (std: low 10%, low-intermediate 51%, intermediate-high 29%, high 10%; exp: low 12%, low-intermediate 44%, intermediate-high 19%, high 25%; p=0.392), advanced clinical stage (std: stage III-IV 94%; exp: 97%; p=0.613), performance status ECOG>1 (std: 23%; exp: 28%; p=0.613), elevated LDH (std: 68%; exp: 69%; p=0.932), presence of B-symptoms (std: 68%; exp: 75%; p=0.524), bulky disease (std: 13%; exp: 13%; p=1.0) and bone marrow involvement (std: 39%; exp: 31%; p=0.535). Histological subtypes were also similarly distributed among both treatment arms (std: PTCL-NOS 55%, AILT 23%, other 22%; exp: PTCL-NOS 56%, AILT 28%, other 16%). No cases of anaplastic large cell PTCL (regardless of ALK-protein status) were included. Neither of the treatment cohorts showed significant treatment delay. The median duration of chemotherapy (calculated for 5 bi-weekly cycles of an expected cumulative duration of 70 days) for non-ALZ vs. ALZ-treated patients was 73 vs. 81 days, respectively. No suspected unexpected serious adverse reactions (SUSARs) were reported. Grade 4 leucopenia was more frequent in ALZ-treated patients (std: 24%, exp: 69%; p=0,001), whereas grade 3–4 anemia and grade 3–4 thrombocytopenia were not significantly different between treatment arms (anemia, std: 19%, exp: 31%; p=0,278; thrombocytopenia, std: 20%, exp: 12%, p=0,682). Non-hematological toxicity unrelated to infectious complications was mild and had a similar frequency in both arms. The number of serious adverse events (SAEs) per patient was 0.86 for patients treated at post-amendment ALZ dose levels, representing a significant reduction compared to the pre-amendment value (3.25), and 0.46 for patients treated in the control arm (p=0.002). The frequency of bacterial and fungal infections (grade ≥3) was similar in both treatment arms. ALZ treated patients had more viral events (9/32; 28% vs. 3/31; 10%), mainly (6 out of 9) consisting of asymptomatic cytomegalovirus reactivations. The overall (non-arm specific) 1-year event-free survival (primary end-point), progression-free survival and overall survival were 55% (95% CI: 42%-67%), 54% (95% CI: 42%-67%) and 78% (95% CI: 67%-88%), respectively.

The safety profile of the current standard and experimental treatment schedules, as well as the interim outcome results, support a continuation of the trial. A final analysis will be performed in Q2 2015.

Jantunen:Genzyme: Has participated in EU Leadership meeting organized by Genzyme as well as Medical Advisory Board meeting organized by Genzyme Other, Honoraria.