Panobinostat activity in both bexarotene-exposed and -naïve patients with refractory cutaneous T-cell lymphoma: Results of a phase II trial

BACKGROUND: Panobinostat is a potent, oral pan-deacetylase inhibitor (pan-DACi) that increases the acetylation of proteins involved in multiple oncogenic pathways. Here, panobinostat is studied in bexarotene-exposed and -naïve patients with refractory cutaneous T-cell lymphoma (CTCL). PATIENTS AND METHODS: Patients with CTCL subtypes mycosis fungoides and Sézary syndrome who received ⩾2 prior systemic therapy regimens received panobinostat (20mg) three times every week. The primary objective was overall response rate (ORR) as determined by a combined evaluation of skin disease and involvement of lymph node and viscera. Disease progression was defined as an unconfirmed, ⩾25% increase in modified Severity Weighted Assessment Tool (mSWAT) compared with nadir. RESULTS: Seventy-nine bexarotene-exposed and 60 bexarotene-naïve patients were enrolled. Reductions in baseline mSWAT scores were observed in 103 patients (74.1%). The ORR was 17.3% in all patients in the primary analysis (15.2% and 20.0% in the bexarotene-exposed and -naïve groups, respectively). The median progression-free survival was 4.2 and 3.7 months in the bexarotene-exposed and -naïve groups, respectively. The median duration of response was 5.6 months in the bexarotene-exposed patients and was not reached at data cutoff in the bexarotene-naïve patients. Additional responses were observed when less-stringent progression criteria were used. The most common adverse events were thrombocytopenia, diarrhoea, fatigue and nausea. Thrombocytopenia and neutropenia were the only grade 3/4 adverse events in >5% of patients and were manageable. CONCLUSION: Despite a very conservative definition of disease progression, panobinostat demonstrated activity with a manageable safety profile in bexarotene-exposed and -naïve CTCL patients. ClinicalTrials.gov Identifier: NCT00425555