Phase 1 Study of CLR 125 in Triple Negative Breast Cancer

NCT07311993 | Recruiting Phase 1 DMC FDA Drug

• 1 other identifier: DCL-25-003
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 3

Brief Summary

The goal of this clinical trial is to evaluate the safety and efficacy of 3 different dose levels of CLR 125 in patients with advanced triple negative breast cancer. The main questions the study aims to answer are:

• What dose and regimen should be used in future trials of CLR 125 in patients with advanced triple negative breast cancer.
• What side effects do participants have when taking CLR 125. Participants will:
• Have CLR 125 administered via infusion 4 times each cycle; repeated every 8 weeks.
• Visit the clinic once every 3 weeks for checkups and testing.
• Report any side effects or new medications. Some participants may also receive one dose of CLR 131 to evaluate the amount of radiation delivered to various organs and to the tumor. These participants will:
• Have 4 scans completed over 2 weeks
• Have blood drawn 6 times over 2 weeks.

Conditions

Breast Cancer

Keywords

triple negative breast cancer

Outcome Measures

Primary Outcomes (2)

• Dose Determination for CLR 125

  Identify the recommended Phase 2 dose and regimen of CLR 125 in advanced TNBC patients

  57 days after initiation of last cycle (each cycle is 57 days)

• Number of adverse events related to study treatment (CLR 125)

  Adverse Events are graded per NCI CTCAE v5.0

  Assessed throughout the study through 1 year following completion of treatment.

Secondary Outcomes (5)

• Efficacy Evaluation for Overall Response Rate

  57 days after initiation of last cycle (each cycle is 57 days)

• Efficacy Evaluation for Progression Free Survival

  Assessed throughout the study through 1 year following completion of treatment

• Efficacy Evaluation for Overall Survival

  Assessed throughout the study through 1 year following completion of treatment

• Evaluation for Duration of Response

  Assessed throughout the study through 1 year following completion of treatment

• Efficacy Evaluation for Duration of Clinical Benefit

  Assessed throughout the study through 1 year following completion of treatment.

Other Outcomes (2)

• Dosimetry Evaluation for Total Body and Normal Organs

  1 hour post-infusion and concluding 11 days post-initial imaging

• Tumor Dosimetry Evaluation of iopofosine I 131 (CLR 131)

  1 hour post-infusion and concluding 11 days post-initial imaging

Study Arms (4)

Dosimetry Phase

OTHER

Iopofosine I 131 (CLR 131) will be administered at 10 mCi on day 1 for approximately 15 patients for imaging purposes.

Drug: Iopofosine I 131

Treatment Phase: CLR 125 Arm 1

EXPERIMENTAL

CLR 125 administered at 65 mCi/m2 fractionated over four doses (day 1, 2, 8, and 9) in each 8-week cycle; patient will receive up to 4 cycles.

Drug: CLR 125

Treatment Phase: CLR 125 Arm 2

EXPERIMENTAL

CLR 125 will be administered at 125 mCi/m2 fractionated over four doses (day 1, 2, 8, and 9) in each 8-week cycle; patient will receive up to 3 cycles.

Drug: CLR 125

Treatment Phase: CLR 125 Arm 3

EXPERIMENTAL

CLR 125 will be administered at 190 mCi/m2 fractionated over four doses (day 1, 2, 8, and 9) in each 8-week cycle; patient will receive up to 2 cycles.

Drug: CLR 125

Interventions

CLR 125 DRUG

Investigational radiopharmaceutical product intended for IV administration.

Treatment Phase: CLR 125 Arm 1; Treatment Phase: CLR 125 Arm 2; Treatment Phase: CLR 125 Arm 3

Iopofosine I 131 DRUG

Investigational radiopharmaceutical product intended for IV administration.

Also known as: CLR 131

Dosimetry Phase

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Unequivocal TNBC histology \[ER and PR less than 10% each and HER-2 negative\].
• Patients that have progressed after at least one prior standard therapeutic regimen given alone or in combination (including, but not limited, to: chemotherapy, immunotherapy, sacituzumab govitecan-hziy, trastuzumab deruxtecan).
• Patients who have received neo-adjuvant or adjuvant therapy must be at least one year from that treatment regimen.
• Patient is ≥ 18 years of age.
• ECOG performance status of 0 to 2.
• Life expectancy ≥ 6 months.
• Patient must meet the following laboratory criteria:
• Platelets ≥ 75,000/uL \[75 x 10\^9/L\]
• White blood cell (WBC) count ≥ 3000/uL
• Absolute neutrophil count ≥ 1500/uL
• Hemoglobin ≥ 9 g/dL
• Estimated glomerular filtration rate ≥ 30 mL/min/1.73 m2 (as reported by the local lab)
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 × upper limit of normal (ULN)
• Bilirubin \< 1.5 × ULN
• At least one measurable lesion, as defined by RECIST v1.1, with longest diameter at baseline ≥ 10 mm (excluding lymph nodes, for which the short diameter must be ≥ 15 mm).

You may not qualify if:

• Antitumor systemic therapy or investigational therapy, within three-half-lives of the agent preceding study drug administration. NOTE: Patients participating in non-interventional clinical trials (i.e., non-drug) are allowed to participate in this trial.
• Focal radiation (including palliative radiation) to non-target lesions should be completed at least 2 weeks prior to dosing.
• For patients receiving CLR 125 after participation in the dosimetry phase, CLR 131 washout is not required prior to dosing with CLR 125.
• Prior targeted radiotherapy.
• Prior external beam radiation therapy resulting in greater than 20% of total bone marrow receiving greater than 20 Gy. For estimation purposes, the following bone marrow percentages can be used:
• Vertebral bodies: Cervical 0.5%, thoracic 1%, lumbar 2% per vertebral body
• Hemipelvis (ilium, acetabulum, ischium): 13% per side
• Sacrum: 10%
• Skull: 12%
• Scapula: 5% per side
• Ribs: 4% per side
• Femur: 3% per side
• Ongoing Grade 2 or greater toxicities due to previous therapies, excluding alopecia, that in the opinion of investigator might be exacerbated by study treatment.
• Patients with prior or concurrent malignancy other than TNBC with the following exceptions, which must be fully treated with no evidence of disease for at least 2 years: non-melanoma skin cancers only requiring topical treatment or surgical excision; melanoma in situ; treated cervical carcinoma in situ; successfully treated prostate cancer.
• Any other concomitant serious illness or organ system dysfunction (including cardiac and pulmonary dysfunction) that in the opinion of the Investigator would either compromise patient safety or interfere with the evaluation of the safety of the test drug.

Sponsors & Collaborators

• Cellectar Biosciences, Inc.: lead

Study Sites (3)

Mayo Clinic Florida

Jacksonville, Florida, 32224, United States

RECRUITING

United Theranostics

Glen Burnie, Maryland, 21061, United States

RECRUITING

United Theranostics

Princeton, New Jersey, 08540, United States

RECRUITING

MeSH Terms

Conditions

Breast Neoplasms; Triple Negative Breast Neoplasms

Interventions

CLR1404

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Study Officials

• Jarrod Longcor

  Cellectar Biosciences

  STUDY DIRECTOR

Central Study Contacts

Kate Oliver

CONTACT

608-441-8120; clinical@cellectar.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: CLR 125 is a radio-iodinated therapy comprising a core phospholipid ether (PLE) analogue radiolabeled with iodine-125. CLR 125 exploits the tumor-targeting properties of PLEs to provide targeted delivery of Auger-emitting radiation to malignant tumor cells and minimizes radiation exposure to normal tissues.

Study Record Dates

• First Submitted: November 13, 2025
• First Posted: December 31, 2025
• Study Start: December 5, 2025
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): July 1, 2029
• Last Updated: May 22, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

US (3)