Phase II Trial of Oral Panobinostat (LBH589) in Patients with Refractory Cutaneous T-Cell Lymphoma (CTCL)

Background: Panobinostat is a histone deacetylase inhibitor that has shown promising results in cutaneous T-cell lymphoma (CTCL). Objectives: An open-label, multicenter, Phase II study is being conducted with a primary objective of establishing the efficacy and safety of the pan-deacetylase inhibitor, panobinostat (LBH589), for patients (pts) with relapsed/refractory CTCL with Stage IB–IVA mycosis fungoides (MF) or Sézary syndrome (SS). Methods: Inclusion criteria include adequate organ function, no clinically significant cardiovascular abnormalities (QTcF ≤450 ms, ECOG PS ≤2), failure of ≥2 prior systemic therapies, and no prior HDAC inhibitor treatment. Pts were grouped as having bexarotene therapy (Group [Gr] 1) or bexarotene naïve (Gr 2). Panobinostat was administered at a dose of 20 mg orally on Days 1, 3, 5, weekly, every 28 days until progression or unacceptable toxicity. Response was based on a composite score, including skin assessment with the modified Severity-Weighted Assessment Tool (mSWAT) and systemic disease assessed by CT scan. Results:  To date, 95 pts (Gr 1=62; Gr 2=33) have enrolled with median age of 58 yrs [range 25–88]: 58 male, 37 female; 70 MF, 25 SS. Median prior treatment regimens are 4 and 3 for Gr 1 and 2, respectively. Most pts were ≥Stage IIB at study entry (Gr 1=42; Gr 2=26) and received 1–17+ (median=3) treatment cycles of panobinostat. In Gr 1, 11/62 pts have had confirmed skin responses by SWAT, including 2 complete skin responses. Confirmatory CT scans are pending for 2 patients. In Gr 2, 4/33 pts had confirmed skin and CT scan responses. Common AEs (>20%; all grades, regardless of causality) included diarrhea, thrombocytopenia, nausea, pruritus, fatigue, and asthenia, and Grade 3/4 AEs (>2%, regardless of causality) included thrombocytopenia, neutropenia, pruritus, diarrhea, and hypophosphatemia. Of 4,542 ECGs analyzed, 2 pts have had QTcF >480 ms; 4 had QTcF >60 ms increase from baseline. Conclusions: Panobinostat continues to demonstrate encouraging clinical activity with a manageable safety profile in pts with CTCL. Per predefined criteria, Group 2 enrollment to Stage 2 is open. Updated efficacy and safety data will be presented.