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Phase 1 Study of CLR 125 in Triple Negative Breast Cancer

A Phase 1b, Open-Label Parallel Study Evaluating CLR 125 in Patients With Relapsed or Refractory Triple Negative Breast Cancer

Status
Recruiting
Phases
Phase 1
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07311993
Enrollment
60
Registered
2025-12-31
Start date
2025-12-05
Completion date
2029-07-01
Last updated
2026-06-03

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast Cancer

Keywords

triple negative breast cancer

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.

Detailed description

This study is designed to determine the recommended dose and regimen for future trials and to evaluate the safety and tolerability of CLR 125 at the selected doses in patients with advanced triple negative breast cancer. It will also determine the antitumor activity (treatment response by RECIST v1.1) through assessment of overall response rate, progression free survival, overall survival, duration of response and duration of clinical benefit of CLR 125 in patients with advanced triple negative breast cancer. Total body, organ, and tumor dosimetry will be assessed in a select number of patients prior to CLR 125 dosing. At the conclusion of the study, total body, organ, and tumor dosimetry will be calculated for the intended patient population, to inform future studies. Up to 60 evaluable patients will be enrolled.

Interventions

Investigational radiopharmaceutical product intended for IV administration.

DRUGCLR 125

Investigational radiopharmaceutical product intended for IV administration.

Sponsors

Cellectar Biosciences, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Intervention model description

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.

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* 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). * Patients with known brain metastases must have completed any radiotherapy or systemic treatments for brain metastases prior to enrollment; by investigator assessment be considered stable with no new signs or symptoms for at least 1 month, and on a stable dose of steroids (unchanged for three weeks prior to registration or on a steroid tapering regimen). * Patients must express willingness and ability to comply with scheduled study visits, treatment plans, laboratory tests, and other study procedures. * Patient or their legally authorized representative must have the ability to understand and provide signed informed written consent before the initiation of any study-related procedures. * Female patients of childbearing potential must have a negative pregnancy test within 24 hours of dosing. * Women of childbearing potential must agree to use a highly effective method of contraception during the study and for 12 months following administration of the study drug. Highly effective methods of contraception include combined (estrogen and progestogen containing) hormonal contraceptives associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone-releasing system, vasectomized partner, or sexual abstinence. Women who have undergone hysterectomy, bilateral oophorectomy, or bilateral tubal ligation, or are post-menopausal (no menses for 12 months without an alternative medical cause) are considered to be of non-childbearing potential. * Men who are able to father a child must agree to use a condom during the study and for 12 months following administration of the study drug.

Exclusion criteria

* 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. * Known history of human immunodeficiency virus or uncontrolled, serious, active infection. * Pregnancy or breast-feeding

Design outcomes

Primary

MeasureTime frameDescription
Dose Determination for CLR 12557 days after initiation of last cycle (each cycle is 57 days)Identify the recommended Phase 2 dose and regimen of CLR 125 in advanced TNBC patients
Number of adverse events related to study treatment (CLR 125)Assessed throughout the study through 1 year following completion of treatment.Adverse Events are graded per NCI CTCAE v5.0

Secondary

MeasureTime frameDescription
Efficacy Evaluation for Overall Response Rate57 days after initiation of last cycle (each cycle is 57 days)To determine the overall response (ORR) rate as assessed by RECIST v1.1.
Efficacy Evaluation for Progression Free SurvivalAssessed throughout the study through 1 year following completion of treatmentTo determine the therapeutic activity defined as Progression Free Survival (PFS) using Kaplan Meier estimator.
Efficacy Evaluation for Overall SurvivalAssessed throughout the study through 1 year following completion of treatmentTo determine the therapeutic activity defined as Overall Survival (OS) using Kaplan Meier estimator.
Evaluation for Duration of ResponseAssessed throughout the study through 1 year following completion of treatmentTo determine the therapeutic activity defined as Duration of Response (DOR) using Kaplan Meier estimator.
Efficacy Evaluation for Duration of Clinical BenefitAssessed throughout the study through 1 year following completion of treatment.To determine the therapeutic activity defined as Duration of Clinical Benefit (DOCB) using Kaplan Meier estimator.

Countries

United States

Contacts

CONTACTKate Oliver
clinical@cellectar.com608-441-8120
STUDY_DIRECTORJarrod Longcor

Cellectar Biosciences

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Jun 4, 2026