Rigel Announces First Patient Enrolled in the Dose Expansion Phase of its Phase 1b Study of R289 in Patients with Lower-Risk MDS
Rigel (Nasdaq: RIGL) announced the first patient has been enrolled in the dose expansion phase of its open-label Phase 1b study of R289 in transfusion dependent relapsed/refractory lower-risk myelodysplastic syndrome (MDS) on Oct 8, 2025. The dose expansion will randomize up to 40 patients to 500 mg once daily or 500 mg twice daily to determine the recommended Phase 2 dose (RP2D).
Enrollment in the dose escalation phase completed in July 2025. The company expects to share updated study data later in 2025. R289 has FDA Orphan Drug and Fast Track designations and remains investigational and not FDA approved.
Rigel (Nasdaq: RIGL) ha annunciato che il primo paziente è stato arruolato nella fase di espansione della dose del suo studio aperto di fase 1b di R289 nella sindrome mielodisplastica MDS a basso rischio dipendente dalle trasfusioni (con recidiva/refrattario) il 8 ottobre 2025. L'espansione della dose randomizzerà fino a 40 pazienti a 500 mg una volta al giorno o 500 mg due volte al giorno per determinare la dose raccomandata per la Fase 2 (RP2D).
Il reclutamento nella fase di escalation della dose è stato completato nel luglio 2025. L'azienda prevede di condividere dati aggiornati sullo studio nel corso del 2025. R289 ha designazioni FDA Orphan Drug e Fast Track e rimane investigazionale e non approvato dalla FDA.
Rigel (Nasdaq: RIGL) anunció que el primer paciente ha sido inscrito en la fase de expansión de dosis de su ensayo abierto de fase 1b de R289 en síndromes mielodisplásicos (MDS) de bajo riesgo dependientes de transfusiones con recaídas/refractarios el 8 de octubre de 2025. La expansión de dosis asignará al azar hasta 40 pacientes a 500 mg una vez al día o 500 mg dos veces al día para determinar la dosis recomendada para la fase 2 (RP2D).
El reclutamiento en la fase de escalado de dosis se completó en julio de 2025. La compañía espera compartir datos actualizados del estudio más adelante en 2025. R289 tiene designaciones de la FDA Orphan Drug y Fast Track y sigue siendo investigacional y no aprobado por la FDA.
Rigel (나스닥: RIGL)은 R289의 오픈 라벨 1b 단계에서 용량 확장 연구의 첫 환자가 등록되었다고 발표했습니다. 이 연구는 수혈 의존 재발/저위험 골수 형성 이상증(MDS)에서 2025년 10월 8일에 해당합니다. 용량 확장은 RP2D를 결정하기 위해 최대 40명의 환자를 500 mg 1일 1회 또는 500 mg 1일 2회로 무작위 배정합니다.
용량 확장 단계의 등록은 2025년 7월에 완료되었습니다. 회사는 2025년 말에 연구 데이터를 업데이트하여 공유할 예정입니다. R289는 FDA의 고아의 약물 및 패스트 트랙 지정을 받았으며, 여전히 연구 중이며 FDA 승인 없이 investigational 상태입니다.
Rigel (NASDAQ : RIGL) a annoncé que le premier patient a été recruté dans la phase d’extension de dose de son essai de phase 1b ouvert R289 chez les syndromes myélodysplasiques (MDS) à faible risque dépendants des transfusions, réfractaires/relapsés, le 8 octobre 2025. L’extension de dose randomisera jusqu’à 40 patients à 500 mg une fois par jour ou 500 mg deux fois par jour afin de déterminer la dose recommandée pour la phase 2 (RP2D).
Le recrutement dans la phase d’escalade de dose s’est terminé en juillet 2025. L’entreprise prévoit de partager des données actualisées sur l’étude plus tard en 2025. R289 bénéficie des désignations FDA Orphan Drug et Fast Track et demeure expérimentale et non approuvée par la FDA.
Rigel (Nasdaq: RIGL) gab bekannt, dass der erste Patient in die Dosiserweiterungsphase seiner offenen Phase-1b-Studie von R289 bei transfusionsabhängigen rezidivierten/refraktären unteren Risikos-MDS aufgenommen wurde am 8. Oktober 2025. Die Dosiserweiterung wird bis zu 40 Patienten randomisieren, 500 mg einmal täglich oder 500 mg zweimal täglich, um die empfohlene Phase-2-Dosis (RP2D) zu ermitteln.
Die Rekrutierung in der Dosis-Eskalationsphase wurde im Juli 2025 abgeschlossen. Das Unternehmen erwartet, später im Jahr 2025 aktualisierte Studiendaten zu veröffentlichen. R289 hat die FDA-Deklarationen Orphan Drug und Fast Track und bleibt weiterhin investigational und nicht von der FDA zugelassen.
ريجل (ناسداك: RIGL) أعلن أن أول مريض تم تسجيله في مرحلة توسيع الجرعة في دراسته من المرحلة الأولى المفتوحة من النوع 1b لــ R289 في متلازمة الخلل النخاعي النخعي قليلة الخطر المعتمدة على النقل بالدم والمتحسسة للانتكاس/المقاومة في 8 أكتوبر 2025. ستقوم توسيع الجرعة بتوزيع عشوائي يصل إلى 40 مريضاً إلى 500 mg مرة يومياً أو 500 mg مرة واحدة يومياً ليومي لتحديد جرعة المرحلة الثانية الموصى بها (RP2D).
اكتمل التسجيل في مرحلة تصعيد الجرعة في يوليو 2025. تتوقع الشركة مشاركة بيانات الدراسة المحدثة في وقت لاحق من عام 2025. لدى R289 تعيينات FDA دواء يتيم (Orphan Drug) و Fast Track وتظل قيد البحث وليست معتمدة من FDA.
Rigel (纳斯达克: RIGL) 宣布，其开放标签的第一阶段 1b 研究中 R289 在需要输血的复发/难治性低风险髓系增生异常综合征(MDS)的剂量扩展阶段的第一例患者已于 2025年10月8日 入组。剂量扩展将随机分配最多 40 名患者，500 mg 每日一次或 500 mg 每日两次，以确定推荐用于阶段 II 的剂量（RP2D）。
剂量爬升阶段的入组已于 2025年7月 完成。公司预计在 2025 年晚些时候分享更新的研究数据。R289 获得 FDA 的 孤儿药 与 快速通道 指定，仍在研究中，尚未获得 FDA 批准。
- First patient enrolled in dose expansion phase on Oct 8, 2025
- Dose escalation phase completed in July 2025
- Up to 40 patients to be randomized to define RP2D
- Orphan Drug and Fast Track designations from FDA
- R289 is investigational and not FDA approved
- Dose expansion limited to up to 40 patients, a small Phase 1b cohort
Insights
Enrollment into the dose expansion signals measured clinical progress; it enables RP2D selection but does not yet de-risk efficacy or safety.
Rigel has advanced R289 into the dose expansion of its Phase 1b program by enrolling the first patient on
The main dependencies are safety, tolerability, and any early signals of hematologic activity observed across the randomized expansion cohorts; those endpoints determine whether an RP2D emerges and whether the program advances. No efficacy or durability data are reported yet, so risk remains until the company releases updated results. Watch for enrollment completion, safety/tolerability readouts, and the company’s planned data update
Dose expansion phase will determine the recommended Phase 2 dose of R289 for patients with transfusion dependent R/R lower-risk MDS
"Today marks an important step in the evaluation of R289 for the treatment of patients with transfusion dependent lower-risk MDS, a disease with a persistent unmet need despite the availability of approved agents. In the dose expansion phase of this study, patients with transfusion dependent R/R lower-risk MDS will be randomized to receive a 500 mg R289 dose either once or twice daily," said Lisa Rojkjaer, M.D., Rigel's chief medical officer. "The outcome of this phase of the study will be the selection of the recommended Phase 2 dose of R289 for future clinical studies. We remain grateful to our investigators for their continued support of our program."
Rigel's open-label, Phase 1b study of R289 is evaluating the safety, tolerability, pharmacokinetics and preliminary activity in patients with R/R lower-risk MDS (NCT05308264). Enrollment in the dose escalation phase of the study was completed in July 2025, and the company expects to share updated data from the study later this year. In the dose expansion phase of the study, up to 40 patients will be randomized into dose levels of 500 mg once daily or 500 mg twice daily to determine the recommended Phase 2 dose (RP2D) for future development of R289. In addition, once the RP2D has been determined, an exploratory cohort of erythropoiesis-stimulating agent (ESA) R/R, or ineligible, lower-risk MDS patients will be evaluated at the RP2D.
R289 was previously granted Orphan Drug designation for the treatment of myelodysplastic syndromes and granted Fast Track designation for the treatment of previously-treated transfusion dependent lower-risk MDS by the FDA.
About R289
R289 is a prodrug of R835, an IRAK1/4 dual inhibitor, which has been shown in preclinical studies to block inflammatory cytokine production in response to toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) family signaling. TLRs and IL-1Rs play a critical role in the innate immune response and dysregulation of these pathways can lead to various inflammatory conditions. Chronic stimulation of both these receptor systems is thought to cause the pro-inflammatory environment in the bone marrow responsible for persistent cytopenias in lower-risk MDS patients.2
About Rigel
Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) is a biotechnology company dedicated to discovering, developing and providing novel therapies that significantly improve the lives of patients with hematologic disorders and cancer. Founded in 1996, Rigel is based in
- R289 is an investigational compound not approved by the FDA.
- Sallman DA et al. Unraveling the Pathogenesis of MDS: The NLRP3 Inflammasome and Pyroptosis Drive the MDS Phenotype. Front Oncol. June 16, 2016. doi: https://doi.org/10.3389/fonc.2016.00151
Forward Looking Statements
This press release contains forward-looking statements relating to, among other things, the potential outcomes of the dose expansion phase of the ongoing Phase 1b study of R289, the potential benefits of R289 as a therapeutic for MDS and lower-risk MDS, the existence of patients with an unmet medical need for such therapy, and Rigel's ability to further develop its clinical stage product candidates, including the ability to share new trial data later this year. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements and as such are intended to be covered by the safe harbor for "forward-looking statements" provided by the PSLRA. Forward-looking statements can be identified by words such as "plan", "potential", "may", "look to", "expects", "outcome", "will" and similar expressions in reference to future periods. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on Rigel's current beliefs, expectations, and assumptions and hence they inherently involve significant risks, uncertainties and changes in circumstances that are difficult to predict and many of which are outside of Rigel's control. Therefore, you should not rely on any of these forward-looking statements. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, the risks and uncertainties of clinical trials and drug development; risks and uncertainties associated with the commercialization and marketing of R289; risks that the FDA or other regulatory authorities may make adverse decisions regarding R289; risks that clinical trials may not be predictive of real-world results or of results in subsequent clinical trials; risks that R289 may have unintended side effects, adverse reactions or incidents of misuses; the availability of resources to develop Rigel's product candidates; market competition; as well as other risks detailed from time to time in Rigel's reports filed with the Securities and Exchange Commission, including its Quarterly Report on Form 10-Q for the quarter ended June 30, 2025 and subsequent filings. Any forward-looking statement made by us in this press release is based only on information currently available to us and speaks only as of the date on which it is made. Rigel does not undertake any obligation to update forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise, and expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein, except as required by law.
Contact for Investors & Media:
Investors:
Rigel Pharmaceuticals, Inc.
650.624.1232
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Media:
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SOURCE Rigel Pharmaceuticals, Inc.
FAQ
What did Rigel (RIGL) announce on October 8, 2025 about R289?
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