Ono Pharmaceutical (4528) R&D Day – ASCO PROSPECT presentation summary

Study background and objectives

• Primary central nervous system lymphoma (PCNSL) is a rare, aggressive lymphoma with limited treatment options and poor prognosis in relapsed/refractory cases.

• No approved drug therapies for PCNSL exist in the US or EU; tirabrutinib is approved in Japan, Taiwan, and South Korea.

• The PROSPECT study evaluated tirabrutinib, a second-generation BTK inhibitor, in US patients with relapsed/refractory PCNSL.

Study design and patient characteristics

• Phase II, open-label, multicenter US study; enrolled adults with measurable brain lesions and prior high-dose methotrexate therapy.

• 48 patients treated; median age 65.5 years; 44% male; most had ECOG PS 1 and received prior rituximab and cytarabine.

• 67 patients screened, 48 enrolled; most discontinued due to disease progression.

Efficacy results

• Overall response rate (ORR) was 67% (95% CI: 52, 80); complete response rate (CRR) was 44%.

• Median duration of response was 9.3 months; median time to response was 1.0 month.

• Median progression-free survival was 6.0 months; median overall survival not reached at cutoff.