PDC Product

Cellectar’s PDC pipeline includes product candidates                                                                                                                                                  for cancer therapy and cancer diagnostic imaging.

PDC Product Pipeline

Cellectar’s product candidates are built upon a cancer cell-targeting delivery and retention platform of optimized phospholipid ether drug conjugates (PDCs). Cellectar’s proprietary PLE carrier platform was deliberately designed to be coupled with multiple payloads to facilitate both therapeutic and diagnostic applications. Several payloads have been conjugated to provide/allow for the targeted delivery of radiotherapeutics, chemotherapeutics, and molecular diagnostics.


Current Partnerships



CLR 131 – Multiple Myeloma & Other Hematologic Malignancies, CLR 125 – Micrometastatic Disease

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Diagnostic/Optical Imaging

CLR 124 – Glioma & CLR 1502 – Breast Cancer Lumpectomy

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Targeted Radiotherapeutics


CLR 131

There is a preponderance of scientific data supporting the sensitivity of hematologic malignancies to radiotherapeutics. Ideally, a cancer-targeted radiopharmaceutical would deliver a cytotoxic radiation dose to all tumor cells while sparing critical normal tissues from consequential radiation dose. Cellectar’s isotope delivery technology is coming closer to this ideal by selectively depositing cytotoxic radiation.

CLR 131 is a small-molecule, cancer-targeting radiotherapeutic PDC designed to deliver cytotoxic radiation directly and selectively to cancer cells and cancer stem cells. CLR 131 is our lead therapeutic PDC product candidate and is currently being evaluated in both Phase 1 and Phase 2 clinical studies. The Investigational New Drug (IND) application was accepted by the U.S. Food and Drug Administration (FDA) in March 2014. In December 2014, the FDA granted orphan drug designation for CLR 131 for the treatment of multiple myeloma and the Phase 1 study was initiated in April 2015. This clinical study is a standard three-by-three dose escalation safety study in patients with relapse or refractory multiple myeloma. Multiple myeloma is an incurable cancer of the plasma cells and is the second most common form of hematologic cancers. This cancer type was selected for clinical, regulatory and commercial rationales, including multiple myeloma’s highly radiosensitive nature, and continued unmet medical need in the relapse/refractory setting. The primary goal of the Phase 1 study is to assess the compound’s safety and tolerability in patients with relapsed or refractory multiple myeloma.

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CLR 131 represents a unique and highly attractive development opportunity because, unlike many early stage oncology therapeutics:

  • CLR 131 utilizes a new cancer cell-selective delivery mechanism to deliver a proven radiotherapeutic to hematologic malignancies
  • CLR 131 leverages a unique mechanism of action distinct from other therapeutic approaches; it does not rely on the inhibition of specific cellular pathways; it works by exposing cancer cells to sustained cytotoxic radiation.
  • CLR 131’s delivery vehicle is a small molecule, meaning that synthesis, physicochemical characterization, and scale-up manufacturing are less involved than similar steps for larger molecules such as monoclonal antibodies and – as a result – are more economical and associated with fewer risks

To learn more, please click on the following link:

Enrollment of First Patient Into Third Cohort of Phase 1 Clinical Study of CLR 131 in Multiple Myeloma

New Positive Data from Phase 1 Clinical Study of CLR 131 In Multiple Myeloma

Lead Compound CLR 131 to Be Studied In Head & Neck Cancer in $12M University of Wisconsin SPORE Grant

Positive Data From Phase 1 Therapeutic Trial of CLR 131 in Multiple Myeloma

CLR 125

CLR 125 is a broad-spectrum, cancer-targeting radiotherapeutic currently under investigation for the treatment of micrometastatic disease. In October, 2015, the company was awarded a national Cancer Institute Fast-Track Small Business Innovation Research (SBIR) grant to further advance its PDC delivery platform through CLR 125 preclinical and clinical research. The collaboration is designed to further explore the targeted delivery of radioisotopes for improved cancer therapy outcomes. The grant is awarded in two installments with up to $2.3 million in funding. Similar to CLR 131, the selective uptake and retention of CLR 125 has been observed in malignant tissues during preclinical studies. CLR 125 uses the radioisotope Iodine-125 (which has a 60-day half-life), which may provide an excellent tumor kinetics match with Cellectar’s proprietary delivery vehicle. Ongoing preclinical research includes: chemistry, manufacturing and controls of CLR 125; biodistribution and toxicity studies of CLR 125 in preclinical models; and efficacy and dose-response studies.

To learn more, please click on the following link:

Cellectar Biosciences Awarded $2.3M National Cancer Institute Fast-Track SBIR Grant to Advance Phospholipid Drug Conjugate (PDC) Delivery Platform

Targeted Chemotherapeutics


Cytotoxic PDCs

Cellectar’s PDC cytotoxics program is based on the conjugation of cytotoxic or cytostatic agents to our PLE delivery platform with the ultimate goal of increasing the therapeutic index; this program ranges from newly discovered to well-characterized chemotherapeutic payloads and may afford improved efficacy, better safety profile, and may allow for the elimination of toxic formulation constituents.

In addition to expanding the therapeutic window of untargeted cytotoxins, Cellectar’s PDC platform provides an opportunity to ‘resurrect’ agents that showed a favorable efficacy profile but unacceptable toxicity profile to continue development.

Conjugation to Cellectar’s PDC platform may also present an attractive life cycle management option by generating new intellectual property for programs nearing the end of their patent protection.

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Our initial product candidates in our CLR 1600 series for proof-of-concept studies and further evaluation currently include Paclitaxel, Gemcitabine, Geldanamycin, and other proprietary cytotoxins as conjugates. Our strategy is to develop the PDC platform technology both internally, as well as externally through strategic partnerships.

In December 2015, the company entered into a collaboration with Laboratoires Pierre Fabre, (the third largest) a French multinational pharmaceutical company. The objective of the research collaboration is to co-design a library of PDC’s employing Pierre Fabre’s natural product-derived chemotherapeutics in combination with our proprietary cancer-targeting delivery vehicle. The newly developed PDC’s may provide enhanced therapeutic indices to otherwise highly potent, non-targeted payloads through the targeted delivery to cancer cells provided by our cancer-targeted delivery vehicle.


To learn more, please click on the following links:
Pierre Fabre Collaboration

Phospholipid Drug Conjugate (PDC) Platform Development Update

Cellectar Biosciences Converts Patent Application for Phospholipid-Ether Analogs as Cancer Targeting Drug Vehicles

Targeted Diagnostics

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CLR 124

Positron emission tomography (PET) used in conjunction with CT scanning has become the imaging method of choice for diagnosis, staging, and treatment assessment in oncology. The PET imaging agent CLR 124 pairs Cellectar’s proprietary PLE delivery platform with iodine-124, a well-established PET imaging isotope with a radiation half-life of four days. In studies to date, CLR 124 selectively illuminated malignant tumors, demonstrating broad-spectrum, cancer-selective uptake and retention. To date, CLR 124 has been administered to 58 patients and shown an excellent safety and tolerability profile.

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In May 2014, Cellectar Biosciences received orphan status designation for CLR 124 as a diagnostic for the management of glioma from the U.S. Food and Drug Administration.

CLR 124 is a ‘Phase 2-ready’ asset and Cellectar is currently seeking partnerships to out-license or co-develop CLR 124 as a Phase 2 asset.

Data courtesy of UW-Madison. Video produced by Dr. Benjamin Titz.


CLR 1502

CLR 1502 is a small-molecule, cancer-targeted, non-radioactive optical imaging agent for use in fluorescence image-guided surgery. CLR 1502 is comprised of Cellectar’s proprietary PLE delivery platform, acting as a cancer-targeted delivery vehicle, covalently attached to a near-infrared fluorophore.

CLR 1502 is being developed for real-time, intraoperative imaging of malignant tissue which will aid in the identification of cancerous lesions and micrometastases during diagnostic, staging, debulking, and curative cancer surgeries. In particular, the potential of CLR 1502 in tumor margin illumination during oncologic resections raises the possibility that this operative aid may improve surgical outcomes.

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CLR 1502 has completed the Pre-IND stage and is a ‘Phase 1-ready’ asset available for out-licensing or co-development under a strategic partnership.


To learn more, please click on the following link:
Chief Scientific Officer Receives International Recognition for Pioneering Research

Peer-Reviewed Glioma Surgery Study With Cellectar Biosciences Fluorescence Cancer-Targeting Agents Chosen for the Cover of Neurosurgery