Ruxolitinib Plus Nivolumab in Patients with R/R Hodgkin Lymphoma after Failure of Check-Point Inhibitors: Preliminary Report on Safety and Efficacy

Background: Recent studies demonstrated that classical Hodgkin lymphoma (cHL) is characterized by chromosome 9p24.1 amplification with associated overexpression of PD-1 ligands as well as JAK2 tyrosine kinase activation. Immune evasion mediated by the PD-1/PD-1 ligand axis can be inhibited with IgG4 agonist antibody specific for human PD-1 nivolumab which has shown excellent overall response rate (ORR) of over 60% in relapsed cHL. JAK2 induces PD-1 ligand expression and augments tumor cell proliferation. JAK2 signaling can be inhibited with clinical grade small molecules (i.e. ruxolitinib). Given this biology, we designed a Phase I/II study to target both pathways in cHL patients who had failed PD-1 blocking agents.

Methods: This is a Phase I/II, multicenter, open-label, dose escalation/dose-expansion study to evaluate the safety and tolerability of ruxolitinib when combined with nivolumab (fixed dose 3mg/kg IV every 2 weeks) in patients with relapsed or refractory (R/R) cHL (NCT03681561). Eligible patients had to fail prior check-point inhibitor (CPI; nivolumab or pembrolizumab). Three dose levels of ruxolitinib were tested: 10 mg orally twice a day (bid), 15 mg bid, and 20 mg bid. Planned duration of therapy was 2 years. The primary objective was to find the maximum tolerated dose (MTD) of ruxolitinib when given with nivolumab and characterize the safety and tolerability of this combination. The phase 2 objective was to evaluate the overall response rate (ORR).

Results: We enrolled 19 patients. Median age was 38 years (range 22-76); 68% were males. Patients were a median of 3.4 years from the initial diagnosis (range 0.9-16.7 years), 89% had stage III-IV disease and all had experienced progressive disease following CPI. 17 (89%) had prior autologous HCT and 1 had prior allogeneic HCT. All patients received nivolumab combined with ruxolitinib, and the highest ruxolitinib dose 20mg BID (MTD) was reached without DLTs. The combination was well tolerated; most AEs were grade 1 and 2. Only 3 patients required hospitalization (2 had pneumonia, one for disease progression). Three patients experienced immune mediated adverse events (LFT elevation: 1 Gr 1 and 1 Gr 2; 1 Gr 3 pneumonitis) and all were reversible. Three subjects were not evaluable for response (2 patients who received < 1 month of therapy due to rapid disease progression and Gr 2 immune hepatitis and 1 patient with short follow-up is not yet evaluable for response). Median follow-up was 13 months (range 3-27 months).

In 16 patients evaluable for response, best ORR was 75% (12 of 16); including 3 CRs (19%), 2 PRs (13%), 6 patients had stable disease (SD, 44%) with tumor bulk reduction ranging from 10-45%. One patient had indeterminate response (negative biopsy of new PET-avid site). Duration of responses were 12.5 months (ranged from 3.7 to 20.4 months); 5 responders continue study therapy and 2 completed 2 years; 1 went on to autologous HCT in PR, and 3 progressed while on therapy after 6, 6 and 23 months. One patient died after later experimental therapy. Progression-free survival at 1 year was 64% (95%CI 34-84%).

Conclusions: Inhibition of JAK2 combined blockade of the PD-1 pathway represent complementary rational therapeutic targets in cHL. Therapy combining ruxolitinib with nivolumab is well tolerated and yield encouragingly high remission rates and durable responses in patients who had all failed previous CPI. Pharmacodynamic and correlative analyses on the mechanism of synergism are underway.