A Multi-Center, Open Label, Phase I/II Study to Assess the Safety and Efficacy of Tenalisib Given in Combination with Romidepsin in Patients with Relapsed/Refractory T-Cell Lymphoma

Background: T cell lymphomas (TCL) have been known to exhibit epigenetic dysregulation and aberrant cell signaling. Tenalisib (RP6530), a highly selective PI3K δ/γ+SIK3 inhibitor has shown clinically promising activity as a single agent in TCL with a differentiated and favorable safety profile. In vitro studies in TCL cell lines showed increased apoptosis when tenalisib was combined with romidepsin (Rhizen data on file). A Phase I/II study of tenalisib in combination with romidepsin was designed to assess safety, pharmacokinetics and efficacy in relapsed/refractory TCL (NCT03770000).

Methods: This is a multi-center, open label, Phase I/II study in patients with T cell lymphoma (PTCL and CTCL). The Phase I is a 3+3 dose escalation study to determine the MTD/optimal dose. The Phase II is an expansion cohort at the MTD/optimal dose of the combination.

Tenalisib was administered orally at doses of 400, 600 and 800 mg BID in combination with romidepsin (12 &14 mg/m^2, Q3W). The objectives of the study are to establish safety, MTD/optimal dose, pharmacokinetics and anti-tumor activity of the combination. We report the dose escalation results and preliminary data from the expansion cohorts.

Results: A total 15 patients were enrolled between July 24, 2019 and July 20, 2020. Baseline demographics are presented in Table 1. Patients had a median of 3 (range; 1-17) prior treatments and 11 (73%) were refractory to their last therapy. About 67% (6/9) of CTCL patients had prior mogamulizumab therapy. No DLT was reported in the dose escalation phase and Tenalisib 800 mg BID+ Romidepsin 14 mg/m^2, Q3W was considered as the optimal dose for expansion cohorts. PK analysis showed linear and dose-dependent kinetics for tenalisib. Co-administration of romidepsin along with tenalisib did not significantly alter the mutual PK of either agents.

Fifteen patients were assessed for safety. Most common treatment emergent adverse events of any grade were nausea (33%), thrombocytopenia (33%) and fatigue (27%). Related ≥ Grade 3 AEs were seen in 5 (33%) patients. These included thrombocytopenia (7%), atrial fibrillation (7%) and pyrexia (7%) which were related to romidepsin while anemia (7%) neutropenia (7%) and rash (7%) were considered related to the combination. There were no instances of transaminitis or colitis. None of the TEAEs led to study discontinuation.

Patients from the dose escalation cohorts (n=9) were evaluated for response. Three patients (3/9) showed complete response (CR), 4 patients (4/9) showed stable disease (SD) while 2 patients (2/9) had progressive disease (PD). Out of the three responders, two were PTCL (AITL) patients, one of which is planned for transplantation, while the third patient was a CTCL (Sezary syndrome) patient who had progressed on prior mogamulizumab therapy. This patient showed rapid reduction of Sezary cell count after 2 cycles of treatment.

Three patients (2 CR, 1 SD) are currently ongoing with a median duration of response being 9.0 (range; 7.6-10.5+) months. The expansion cohort has 6 patients and is currently enrolling.

Conclusions: The combination of tenalisib and romidepsin demonstrates a favorable safety profile and promising indicators of combined anti-tumour activity in patients with R/R TCL. The expansion cohort in CTCL and PTCL is currently underway to validate these encouraging early results. Updated results will be presented during the ASH meeting.