Efficacy and safety of copanlisib in patients with relapsed or refractory marginal zone lymphoma

Marginal zone lymphoma (MZL) is challenging to treat, with many patients relapsing following initial treatment. We report the long-term efficacy and safety of copanlisib, a pan-class I phosphoinositide 3-kinase (PI3K) inhibitor, in the subset of 23 patients with relapsed/refractory MZL treated in the phase 2 CHRONOS-1 study (#NCT01660451, Part B; www.clinicaltrials.gov). Patients had a median of 3 prior lines of therapy, including rituximab and alkylating agents, and received IV copanlisib 60 mg on days 1, 8, and 15 of 28-day cycles for a median of 23 weeks. The objective response rate was 78.3% (18/23; 3 complete responses and 15 partial responses). The median duration of response was 17.4 months (median follow-up, 9.4 months), and median time to response was 2.1 months. Median progression-free survival was 24.1 months (median follow-up, 10.3 months), and median overall survival was not reached (median follow-up, 28.4 months). The most common all-grade treatment-emergent adverse events (TEAEs) included fatigue (52.2%, 12/23), diarrhea, and transient, infusion-related hyperglycemia (each 47.8%, 11/23). Nineteen patients (82.6%) had grade 3/4 TEAEs, most commonly transient, infusion-related hyperglycemia and hypertension (each 39.1%, 9/23). TEAEs led to dose reduction or dose interruptions /delays in 9 patients (39.1%) and 18 patients (78.3%), respectively. Patients with activated PI3K/B-cell antigen receptor signaling had improved response rates. Overall, copanlisib demonstrated strong efficacy, with a short time to objective response, improved objective response rate with longer treatment duration, durable responses, and manageable safety, in line with previous reports. These data provide rationale for long-term treatment with copanlisib in patients with relapsed/refractory MZL.