Phase Ib of Copanlisib in Combination with Ibrutinib in Recurrent/Refractory Primary CNS Lymphoma (PCNSL)

BACKGROUND: PCNSL is an aggressive primary brain tumor with median progression free survival (PFS) after upfront methotrexate-based chemotherapy of 2-3 years. Outcome and treatment options are poor for recurrent/refractory (r/r) disease. This trial combines the pan-PI3K inhibitor copanlisib with Ibrutinib in patients with r/r PCNSL.

METHODS: Eligible patients had r/r PCNSL, age≥18, ECOG≤2, normal end-organ function, and an unrestricted number of CNS directed prior therapies. Ibrutinib was given orally daily; copanlisib intravenously on days 1, 8, and 15 of each 28-day cycle.

RESULTS: Six patients have been enrolled so far and received copanlisib at 60 mg and ibrutinib at 560 mg. Median age was 68 (range 50-77); 3 were women. Median ECOG was 1 (0: 2, 1: 3, 2: 1). All had recurrent parenchymal disease. Three had additional cerebrospinal fluid (CSF) involvement. Two had received prior single-agent ibrutinib. Initially, no prophylactic antimicrobial treatment was required. PCP prophylaxis was made mandatory after one patient developed PCP pneumonia leading to a grade 5 lung infection. Four patients are still on trial and one withdrew due to personal choice. Two grade 4 adverse events were observed in 2 patients (LFT elevation, lymphopenia); four grade 3 events in 3 patients (rash, lymphopenia, LFT elevation). The most common toxicities at any grade were transient, infusion-related hyperglycemia and hypertension. No Aspergillus infections have been observed. Enrollment into the next dose level (copanlisib 60 mg, ibrutinib 840 mg) is ongoing. After a median follow-up of 180 days (range 46-249), all patients were evaluated for response with an overall response rate of 67% with 1 CR, 3 PR, 1 SD and 1 PD as best response.

CONCLUSION: Treatment with copanlisib and ibrutinib in patients with PCNSL has manageable adverse events after initiation of mandatory PCP prophylaxis. Clinical response was seen in 67% of patients.