Final Results of a Phase II Trial of Belinostat (PXD101) in Patients with Recurrent or Refractory Peripheral or Cutaneous T-Cell Lymphoma.

Belinostat is a pan-HDAC inhibitor of the hydroxamate chemical class that is well-tolerated and has shown clinical activity.

Open label, multicenter trial enrolling patients (pts) with peripheral T-cell lymphoma (PTCL) or cutaneous T-cell lymphoma (CTCL) who failed ≥ 1 prior systemic therapy. Pts received 1000 mg/m² IV belinostat over 30 min on days 1 to 5 of a 3-wk cycle. Primary endpoint was objective response (OR) assessed by IWG criteria for PTCL and by SWAT (cutaneous lesions) and IWG criteria (non-cutaneous lesions) for CTCL. Pruritus in pts with CTCL was assessed using a 10-point scale; relief defined as reduction of pruritus score of ≥ 3 points in pts with baseline score ≥ 3. ECGs were monitored and reviewed centrally (pre-/ post-infusion ECGs on all treatment days in cycle 1, and pre-/ post-infusion ECGs on day 1 of subsequent cycles) to evaluate potential cardiac toxicity.

The study enrolled a total of 53 treated pts, including 20 and 29 evaluable pts with a diagnosis of PTCL and CTCL, respectively. The 20 pts with PTCL [10 PTCL-unspecified (PTCL-U), 3 anaplastic large cell lymphoma (ALCL), 3 angioimmunoblastic TCL (AITL), 3 NK/T-cell lymphoma, and 1 subcutaneous panniculitis-like TCL (SPTCL)] had received a median of 3 prior systemic therapies (range 1 – 10), and 40 % of them had stage IV disease. 5/20 (25%) PTCL pts responded with 2 CR (both in patients with PTCL-U) and 3 PR (PTCL-U, AITL, ALCL). The 5 responding pts had a median duration of response of 159+ days (range 1 – 504+). Additionally, SD was observed in 5 pts (2 PTCL-U, 2 NK/T-cell, and 1 ALCL) with median duration of SD of 109+ days (range 80 -185+).

The 29 pts with CTCL [15 mycosis fungoides (MF), 7 Sezary syndrome (SS), 5 non MF/SS, 2 unclassified] had received a median of 1 prior skin directed therapies (range 0 – 4) and 3 prior systemic therapies (range 1 – 9), and 55 % of them had stage IV disease. 4/29 (14%) CTCL pts responded with 2 CR (ALCL, MF) and 2 PR (MF, SS). The 4 responding pts had a median duration of response of 273 days (range 48 - 469+). Importantly, time to response was short with a median of 16 days (range 14-35). In addition, SD was observed in 17 pts (10 MF, 3 SS, 2 non MF/SS, 2 unclassified) with current duration of up to 127 days. Pruritus relief (score reduction ≥ 3) was seen in 7 of 14 pts with significant baseline pruritis. Median time to pruritus relief was also short, 16 days (range 7-45).

Hematological toxicity was minimal without any grade 4 events (shift from baseline) and only one pt each experiencing grade 3 neutropenia and grade 3 thrombocytopenia, respectively. No grade 3 QTcF prolongation was detected in more than 700 ECGs. Four grade 3/4 drug-related AEs were reported: pruritis, rash/erythema, edema, and adynamic ileus.

Belinostat monotherapy is safe, well tolerated, and efficacious in pts with recurrent/refractory T-cell lymphoma with durable remissions in both CTCL and PTCL. These results are the basis for a pivotal study with belinostat monotherapy in pts with PTCL.

Advani:Seattle Genetics, Inc.: Research Funding. Duvic:Topotarget: research support for conduct of clinical trial. Fagerberg:TopoTarget A/S: Employment, Equity Ownership. Foss:Eisai : Speakers Bureau.