PROSPECT Study of Tirabrutinib in R/R PCNSL Completes Part A Enrollment

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The first arm of the phase 2 PROSPECT study evaluating tirabrutinib for the treatment of relapsed/refractory primary central nervous system lymphoma has finished enrolling patients.

Red blood cells: © vipman4 - stock.adobe.com

Red blood cells: © vipman4 - stock.adobe.com

Part A of the phase 2 PROSPECT study (NCT04947319), which is evaluating the efficacy and safety of tirabrutinib (ONO-4059) in patients with relapsed/refractory (R/R) primary central nervous system lymphoma (PCNSL) has completed enrollment.1

"Completing enrollment of the first arm of this US study is an important step in bringing a therapeutic option to patients with R/R PCNSL in the US. We are very grateful to everyone involved with this clinical trial," said Kiyoaki Idemitsu, executive officer, executive director, clinical development of ONO PHARMA, in a press release.

PROSPECT Study of Tirabrutinib in PCNSL

Trial Name: An Open-label Phase II Study to Investigate the Efficacy, Safety, and Pharmacokinetics of Tirabrutinib in Patients With Primary Central Nervous System Lymphoma (PCNSL)

ClinicalTrials.gov Identifier: NCT04947319

Sponsor: Ono Pharmaceutical Co. Ltd

Recruitment Contact: Ono Pharma USA, Inc., 6179044500, PROSPECTstudy@ono-pharma.com

Completion Date: March 31, 2027

The first arm of this study is assessing the tirabrutinib for the treatment of patients with R/R PCNSL who received prior treatment with high-dose methotrexate-based regimens.

While enrollment is now complete for part A of the study, the second arm (part B) continues to enroll patients who are newly diagnosed with and previously untreated for PCNSL. This portion of the study plans to evaluate tirabrutinib in combination with 1 of 2 high-dose methotrexate-based regimens as first-line therapy.

"This is an important milestone for ONO as it builds its clinical trial program in the US," said Kunihiko Ito, president and chief executive officer of ONO PHARMA USA, in a press release. "For decades, ONO's commitment to innovation in oncology has helped change treatment paradigms for patients all over the world. We look forward to continuing this legacy as we investigate tirabrutinib for PCNSL in the US.”

About Tirabrutinib and the PROSPECT Study in PCNSL

Tirabrutinib is a highly selective irreversible Bruton tyrosine kinase inhibitor. Previously in March 2023, an orphan drug designation was granted to tirabrutinib by the FDA for the treatment of patients with PCNSL.

The agent is currently an approved treatment option in Japan, Taiwan, and South Korea for this patient population.

In the open-label, phase 2 study to investigating the efficacy, safety, and pharmacokinetics of tirabrutinib in PCNSL, there is an estimated enrollment of 112 patients.2 For part A of the trial, enrollment was open to patients aged ≥ 18 years on the day of consenting to the study who had a pathologic diagnosis of PCNSL, relapsed or refractory PCNSL with at least 1 prior high-dose methotrexate-based therapy for PCNSL, and a measurable brain lesion with a minimum diameter > 1.0 cm. Patients must have had an ECOG performance status of 0, 1, or 2; a life expectancy of at least 3 months; and adequate bone marrow, renal, and hepatic function.

Part B of the study is also open to patients aged ≥ 18 years on the day of consenting to the study. They must have a pathologic diagnosis of PCNSL within the past 3 months; have no prior antitumor treatments for PCNSL; have a measurable brain lesion with a minimum diameter > 1.0 cm; an ECOG performance status of 0 to 2; a life expectancy of at least 6 months; and adequate bone marrow, renal, and hepatic function. Further, patients are eligible for enrollment if, in the opinion of the investigator, they are suitable to receive treatment with a high-dose methotrexate-containing regimen.

The primary end points are overall response rate for part A and tirabrutinib dose estimate, incidence and severity of adverse effects (AEs), and complete response rate for part B. Secondary end points include duration of response, time to response, best overall response, AEs, pharmacokinetics, and laboratory abnormality profile of tirabrutinib for parts A and B of the study. Change in corticosteroid dose is a secondary end point being evaluated in part A only.

REFERENCES:
1. ONO PHARMA announces enrollment is complete for the first arm of the PROSPECT study of tirabrutinib in U.S. patients with relapsed or refractory PCNSL. News release. ONO Pharmaceuticals, Co., Ltd. March 25, 2024. Accessed March 25, 2024. https://tinyurl.com/2xr4v6n2
2. Study of tirabrutinib (ONO-4059) in patients with primary central nervous system lymphoma (PROSPECT Study). ClinicalTrials.gov. December 26, 2023. Accessed March 25, 2024. https://clinicaltrials.gov/study/NCT04947319

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