Cellectar Biosciences Submits Phase 1b Clinical Trial Protocol to US Food and Drug Administration for CLR 125 to Treat Triple-Negative Breast Cancer (TNBC)
Cellectar Biosciences (NASDAQ:CLRB) has submitted a protocol to the FDA for a Phase 1b dose-finding study of CLR 125, an Auger-emitting radiopharmaceutical for treating triple-negative breast cancer (TNBC). The study will evaluate three different dosing regimens across 15 patients per arm, totaling 45 patients.
The trial aims to determine the recommended Phase 2 dose, assess safety and tolerability, and evaluate initial response using RECIST criteria and progression-free survival. CLR 125 showed promising preclinical results, demonstrating good tolerability and robust tumor uptake in TNBC animal models. The drug leverages the company's PDC-targeted delivery platform to deliver iodine-125 directly to cancer cell nuclei and mitochondria.
Cellectar Biosciences (NASDAQ:CLRB) ha presentato un protocollo alla FDA per uno studio di Fase 1b volto a individuare la dose ottimale di CLR 125, un radiofarmaco emettitore di Auger per il trattamento del carcinoma mammario triplo negativo (TNBC). Lo studio valuterà tre diversi regimi posologici su 15 pazienti per gruppo, per un totale di 45 pazienti.
Lo studio mira a determinare la dose raccomandata per la Fase 2, a valutare la sicurezza e la tollerabilità, e a esaminare la risposta iniziale utilizzando i criteri RECIST e la sopravvivenza libera da progressione. CLR 125 ha mostrato risultati preclinici promettenti, dimostrando buona tollerabilità e un forte assorbimento tumorale nei modelli animali di TNBC. Il farmaco sfrutta la piattaforma di consegna mirata PDC dell'azienda per trasportare direttamente lo iodio-125 nei nuclei e nei mitocondri delle cellule tumorali.
Cellectar Biosciences (NASDAQ:CLRB) ha presentado un protocolo a la FDA para un estudio de fase 1b destinado a encontrar la dosis adecuada de CLR 125, un radiofármaco emisor de Auger para el tratamiento del cáncer de mama triple negativo (TNBC). El estudio evaluará tres regímenes de dosificación diferentes con 15 pacientes por grupo, sumando un total de 45 pacientes.
El ensayo tiene como objetivo determinar la dosis recomendada para la fase 2, evaluar la seguridad y tolerabilidad, y analizar la respuesta inicial usando los criterios RECIST y la supervivencia libre de progresión. CLR 125 mostró resultados preclínicos prometedores, demostrando buena tolerabilidad y una fuerte captación tumoral en modelos animales de TNBC. El fármaco aprovecha la plataforma de entrega dirigida PDC de la compañía para llevar yodo-125 directamente a los núcleos y mitocondrias de las células cancerosas.
Cellectar Biosciences (NASDAQ:CLRB)는 삼중음성 유방암(TNBC) 치료를 위한 오거 방출 방사성 의약품 CLR 125의 1b상 용량 탐색 연구 프로토콜을 FDA에 제출했습니다. 이 연구는 각 군당 15명의 환자, 총 45명의 환자를 대상으로 세 가지 다른 투여 요법을 평가할 예정입니다.
이번 임상시험은 2상 권장 용량을 결정하고, 안전성과 내약성을 평가하며, RECIST 기준과 무진행 생존율을 사용해 초기 반응을 평가하는 것을 목표로 합니다. CLR 125는 TNBC 동물 모델에서 좋은 내약성과 강력한 종양 흡수를 보여주는 유망한 전임상 결과를 나타냈습니다. 이 약물은 회사의 PDC 표적 전달 플랫폼을 활용하여 요오드-125를 암세포의 핵과 미토콘드리아에 직접 전달합니다.
Cellectar Biosciences (NASDAQ:CLRB) a soumis un protocole à la FDA pour une étude de phase 1b visant à déterminer la dose optimale de CLR 125, un radiopharmaceutique émetteur d'Auger pour le traitement du cancer du sein triple négatif (TNBC). L'étude évaluera trois schémas posologiques différents sur 15 patients par groupe, soit un total de 45 patients.
L'essai a pour objectif de déterminer la dose recommandée pour la phase 2, d'évaluer la sécurité et la tolérabilité, et d'analyser la réponse initiale selon les critères RECIST ainsi que la survie sans progression. CLR 125 a montré des résultats précliniques prometteurs, démontrant une bonne tolérabilité et une forte absorption tumorale dans des modèles animaux de TNBC. Le médicament utilise la plateforme de délivrance ciblée PDC de la société pour acheminer l'iode-125 directement dans les noyaux et mitochondries des cellules cancéreuses.
Cellectar Biosciences (NASDAQ:CLRB) hat der FDA ein Protokoll für eine Phase-1b-Dosisfindungsstudie mit CLR 125 vorgelegt, einem Auger-emittierenden Radiopharmazeutikum zur Behandlung von triple-negativem Brustkrebs (TNBC). Die Studie wird drei verschiedene Dosierungsregime mit jeweils 15 Patienten pro Gruppe, insgesamt 45 Patienten, untersuchen.
Ziel der Studie ist es, die empfohlene Dosis für Phase 2 zu bestimmen, die Sicherheit und Verträglichkeit zu bewerten sowie die erste Ansprechrate anhand der RECIST-Kriterien und das progressionsfreie Überleben zu analysieren. CLR 125 zeigte vielversprechende präklinische Ergebnisse mit guter Verträglichkeit und starker Tumoraufnahme in TNBC-Tiermodellen. Das Medikament nutzt die PDC-zielgerichtete Lieferplattform des Unternehmens, um Iod-125 direkt in die Zellkerne und Mitochondrien von Krebszellen zu transportieren.
- Promising preclinical results showing good tolerability and robust tumor uptake in TNBC models
- Potential expansion into multiple solid tumor types including triple negative breast, lung and colorectal cancers
- Building on existing proof-of-concept and tolerability data from Phase 2 trial of similar compound iopofosine I 131
- Early-stage Phase 1b trial with outcomes yet to be determined
- Will require multiple clinical trial phases before potential commercialization
- Faces competition in the challenging TNBC treatment landscape
Insights
Cellectar's FDA submission for CLR 125 represents significant advancement in targeting aggressive TNBC with potential nuclear-targeting radiotherapy.
Cellectar has submitted a Phase 1b dose-finding protocol to the FDA for CLR 125, an Auger-emitting radiopharmaceutical targeting triple-negative breast cancer (TNBC). This represents a crucial developmental milestone for the company's second radiotherapeutic agent. The significance lies in the mechanism of action - CLR 125 uses iodine-125, an Auger electron emitter with extremely short-range radiation effects, potentially allowing for precise tumor targeting while minimizing collateral damage to surrounding healthy tissues.
The proposed trial design is methodologically sound, evaluating three distinct dosing regimens (32.75 mCi x 4 cycles, 62.5 mCi x 3 cycles, and 95 mCi x 2 cycles) with 15 patients per arm. Importantly, the trial incorporates imaging to confirm tumor uptake - a critical element for radiopharmaceuticals that will provide early evidence of target engagement. The primary endpoint appropriately focuses on determining the recommended Phase 2 dose while collecting preliminary efficacy signals through RECIST criteria and progression-free survival.
What's particularly promising is that CLR 125 leverages Cellectar's established phospholipid ether (PLE) delivery platform, which has shown proof-of-concept with their lead compound iopofosine I 131. The molecular similarity between these compounds suggests potential transferability of safety and efficacy profiles. The PLE technology's reported ability to deliver the radioisotope directly to cancer cell nuclei and mitochondria could theoretically enhance cytotoxicity while limiting off-target effects - particularly valuable in TNBC where targeted therapies are limited.
Good Tolerability and Robust Tumor Uptake were Observed in TNBC Animal Models
Auger Emitters Offer the Potential Benefit of Enhanced Cytotoxicity, Safety and Ease-of-Use
FLORHAM PARK, N.J., June 24, 2025 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (Nasdaq: CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of drugs for the treatment of cancer, today announced that the company has submitted a protocol with the U.S. Food and Drug Administration (FDA) for a Phase 1b Dose Finding study of its Auger emitting radiopharmaceutical, CLR 125, for the treatment of relapsed TNBC. CLR 125 is an iodine-125 Auger-emitting drug candidate targeting solid tumors, such as triple negative breast, lung and colorectal cancers.
“Building on the promising preclinical results with CLR 125, we have submitted a Phase 1b dose-finding study protocol to the FDA for the treatment of triple-negative breast cancer, including metastatic disease. This study leverages the unique potential ability of our PLE to deliver iodine-125 directly to the nucleus and mitochondria, which is designed to achieve potent activity while minimizing the risk of adverse effects due to its limited transmission range,” said Jarrod Longcor, Cellectar’s chief operating officer. “Initiating this Phase 1b study is a significant milestone and an important step toward evaluating the safety and optimal dosing of CLR 125 in patients, ultimately providing a potential new treatment option for those afflicted by this challenging disease.”
The proposed Phase 1b dose finding study in relapsed TNBC will utilize imaging to determine tumor uptake to evaluate three doses of CLR 125 (32.75 mCi for 4 cycles, 62.5 mCi for 3 cycles, and 95 mCi for 2 cycles) with four doses per cycle in 15 patients per arm. The primary endpoint of the study will be to determine the recommended Phase 2 dose and dosing regimen and will also evaluate safety and tolerability, as well as initial response assessment (RECIST and progression-free survival).
“The integration of our PDC-targeted delivery platform with a precision-driven, Auger-emitting isotope represents a powerful therapeutic combination with the potential to deliver significant clinical benefit across a range of solid tumors, including TNBC. Our confidence in CLR 125 is grounded in its molecular similarity to iopofosine I 131, our PDC designed to provide targeted delivery of iodine-131 (radioisotope), for which we have evidence supporting proof-of-concept and tolerability in a Phase 2 clinical trial,” said James Caruso, chief executive officer of Cellectar. “Leveraging dosimetry imaging to measure drug delivered directly to tumors is expected to provide early proof-of-concept of the appropriate dose.”
About Triple Negative Breast Cancer
Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of estrogen receptors, progesterone receptors, and HER2 protein expression. This lack of common therapeutic targets makes TNBC particularly challenging to treat, with limited options beyond chemotherapy. TNBC tends to grow and spread more quickly than other breast cancer types and disproportionately affects younger women and those of African descent. In the U.S., approximately
About Cellectar Biosciences, Inc.
Cellectar Biosciences is a late-stage clinical biopharmaceutical company focused on the discovery and development of proprietary drugs for the treatment of cancer, independently and through research and development collaborations. The company’s core objective is to leverage its proprietary Phospholipid Drug Conjugate™ (PDC) delivery platform to develop the next-generation of cancer cell-targeting treatments, delivering improved efficacy and better safety as a result of fewer off-target effects.
The company’s product pipeline includes: iopofosine I 131, a PDC designed to provide targeted delivery of iodine-131 (radioisotope), for which the FDA has granted Breakthrough Therapy Designation; CLR 121225, an actinium-225 based program being targeted to several solid tumors with significant unmet need, such as pancreatic cancer; and CLR 121125, an iodine-125 Auger-emitting program targeted in other solid tumors, such as triple negative breast, lung and colorectal, as well as proprietary preclinical PDC chemotherapeutic programs and multiple partnered PDC assets.
In addition, iopofosine I 131 has been studied in Phase 2b trials for relapsed or refractory multiple myeloma (MM) and central nervous system (CNS) lymphoma, and the CLOVER-2 Phase 1b study, targeting pediatric patients with high-grade gliomas, for which Cellectar is eligible to receive a Pediatric Review Voucher from the FDA upon approval. The FDA has also granted iopofosine I 131 six Orphan Drug, four Rare Pediatric Drug and two Fast Track Designations for various cancer indications.
For more information, please visit www.cellectar.com or join the conversation by liking and following us on the company’s social media channels: X, LinkedIn, and Facebook.
Forward Looking Statement Disclaimer
This news release contains forward-looking statements. You can identify these statements by our use of words such as "may," "expect," "believe," "anticipate," "intend," "could," "estimate," "continue," "plans," or their negatives or cognates. These statements are only estimates and predictions and are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. These statements are based on our current beliefs and expectations as to such future outcomes. Drug discovery and development involve a high degree of risk. Factors that might cause such a material difference include, among others, uncertainties related to the ability to identify suitable collaborators, partners, licensees or purchasers for our product candidates and, if we are able to do so, to enter into binding agreements with regard to any of the foregoing, or to raise additional capital to support our operations, or our ability to fund our operations if we are unsuccessful with any of the foregoing. A complete description of risks and uncertainties related to our business is contained in our periodic reports filed with the Securities and Exchange Commission including our Form 10-K for the year ended December 31, 2024, and our Form 10-Q for the quarter ended March 31, 2025. These forward-looking statements are made only as of the date hereof, and we disclaim any obligation to update any such forward-looking statements.
Contact
INVESTORS:
Anne Marie Fields
Precision AQ
212-362-1200
annemarie.fields@precisionaq.com
1 Source: Triple-negative breast cancer recurrence: Outlook and treatment
2 Source: Triple-Negative Breast Cancer Recurrence After Mastectomy
3 Source: National Cancer Institute
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