Dose Escalation Study of CLR 131 in Children, Adolescents, and Young Adults With Relapsed or Refractory Malignant Tumors Including But Not Limited to Neuroblastoma, Rhabdomyosarcoma, Ewings Sarcoma, and Osteosarcoma (CLOVER-2)
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ClinicalTrials.gov Identifier: NCT03478462 |
Recruitment Status :
Active, not recruiting
First Posted : March 27, 2018
Last Update Posted : May 17, 2023
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Condition or disease | Intervention/treatment | Phase |
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Pediatric Solid Tumor Pediatric Lymphoma Pediatric Brain Tumor DIPG Neuroblastoma Ewing Sarcoma Rhabdomyosarcoma Osteosarcoma | Drug: CLR 131 | Phase 1 |
Even with standard, highly toxic multimodality therapies and salvage regimen, most pediatric patients with primary metastatic or relapsed solid tumors are confronted with a poor prognosis. For these patients there is currently no accepted successful treatment regimen. There is a need for new drugs, including targeted radiopharmaceuticals, preferably with cancer-specific uptake and broad applicability for these rare pediatric malignancies.
CLR 131 is a radioiodinated therapeutic that exploits the selective uptake and retention of phospholipid ethers (PLEs) by malignant cells. Cellectar Biosciences' novel cancer-targeted small-molecule compound (CLR1404) is radiolabeled with the isotope iodine-131 (I-131). CLR 131 has demonstrated tumor selective uptake across numerous adult and pediatric cancer cell types. Therapeutic efficacy has been demonstrated in various pediatric and adult-type cancer xenograft models, confirming the ability of CLR 131 to target tumors.
Based on the critical unmet medical need for effective agents with novel mechanisms of action in relapsed pediatric cancers and initial preclinical and clinical experience with radioiodinated CLR1404, Cellectar Biosciences has chosen to assess CLR 131 in a phase 1 pediatric trial.
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 30 participants |
Allocation: | N/A |
Intervention Model: | Single Group Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | An Open-Label, Dose Escalation, Efficacy, and Safety Study of CLR 131 in Children, Adolescents, and Young Adults With Select Solid Tumors, Lymphoma, and Malignant Brain Tumors |
Actual Study Start Date : | April 30, 2019 |
Actual Primary Completion Date : | September 25, 2022 |
Estimated Study Completion Date : | December 2024 |

Arm | Intervention/treatment |
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Experimental: CLR 131
CLR 131 intravenous administration
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Drug: CLR 131
IV dose of CLR 131, increased/decreased by dose level; single or fractionated dose
Other Name: I-131-CLR1404 |
- Number of participants with dose limiting toxicities (DLT) [ Time Frame: up to 64 days ]DLT will be assessed by physical examination, vital signs, and laboratory values
- Identification of recommended phase 2 dose of CLR 131 in children, adolescents, and young adults [ Time Frame: until non-tolerated dose is defined; dose escalation decision made upon review of data from a complete cohort (85 days after all subjects in cohort have received infusion) ]Dose and regimen to be used in Phase 2 trials of CLR 131 in children, adolescents, and young adults
- Determination of preliminary antitumor activity of CLR 131 in children, adolescents, and young adults [ Time Frame: through Day 85 ]Response assessment per applicable criteria (e.g., Neuroblastoma Response Criteria (modified); RECIST 1.1; positron emission tomography response criteria in solid tumors (PERCIST); RANO)
- Determination of therapeutic activity of CLR 131 in children, adolescents, and young adults [ Time Frame: up to 22 days post initial infusion ]Assessment via 131-I/CLR 131 SPECT/CT scans
- Determination of event free survival following CLR 131 infusion in children, adolescents, and young adults [ Time Frame: 1 month to 5 years ]Time from first infusion of CLR 131 until progression or recurrence of disease
- Determination of overall survival following CLR 131 infusion in children, adolescents, and young adults [ Time Frame: 1 month to 5 years ]Time from first infusion of CLR 131 until death due to any reason
- Determine dosimetry of CLR 131 in children, adolescents, and young adults [ Time Frame: up to 15 days post initial infusion ]Assessment of dosimetry via whole body planar imaging

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Ages Eligible for Study: | 2 Years to 25 Years (Child, Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
All Patients
- Previously confirmed (histologically or cytologically) pediatric solid tumor (e.g., neuroblastoma, sarcoma), lymphoma (including Hodgkin's lymphoma), or malignant brain tumors that are clinically or radiographically suspected to be relapsed, refractory, or recurrent for which there are no standard treatment options with curative potential. Note: patients with diffuse intrinsic pontine glioma (DIPG) may enroll without histological or cytological confirmation.
- ≥ 2 years of age and ≤ 25 years of age at time of consent/assent
- If ≥ age 16 years, Karnofsky performance status of ≥ 60. If < age 16 years, Lansky performance status ≥ 60
- Platelets ≥ 75,000/µL (last transfusion, if any, must be at least 1 week prior to study registration, and, unless deemed medically necessary, no transfusions are allowed between registration and dosing)
- Absolute neutrophil count ≥ 750/µL
- Hemoglobin ≥ 8 g/dL (last transfusion must be at least 1 week prior to study registration, and, unless deemed medically necessary, no transfusions are allowed between registration and dosing)
- Using the bedside Schwartz formula, estimated GFR (creatinine clearance) > 60 ml/min/1.73m2
- Alanine aminotransferase < 3 × ULN
- Bilirubin < 2 × ULN
- Patients who have undergone autologous or allogeneic bone marrow transplant must be at least 3 months from transplant.
- Patients enrolling at total dose levels > 30 millicurie (mCi)/m2 must have availability or ability to collect an autologous hematopoietic stem cell back-up product prior to CLR 131 administration. At minimum, 2 x 10^6/kg cryopreserved CD34+ cells must be available.
- Patient or his or her legal representative is judged by the Investigator to have the initiative and means to be compliant with the protocol.
Patients with Pediatric Solid Tumor or Lymphoma
- At least 1 measurable lesion with longest diameter of at least 10 mm. Patients with a lesion(s) that are determined to be Metaiodobenzylguanidine (MIBG) or positron emission tomography (PET) positive may be enrolled at the investigator's discretion, even if not associated with a measurable lesion of at least 10 mm. Patients with neuroblastoma who have detectable disease may enroll provided they meet the requirements of the International Neuroblastoma Response Criteria.
- 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 with Recurrent or Refractory Brain Tumors
- At least 1 measurable lesion with longest diameter of at least 10 mm on any imaging sequence.
- Patients with previously known neurological deficits must be clinically stable at time of enrollment and able to complete all study related procedures. Patients with documented or newly diagnosed neurological deficits will be enrolled at the investigator's discretion.
- If patient receives steroids for neurological symptom control, the dose must be stable (unchanged for three weeks prior to registration) or on a steroid tapering regimen. Initiation of steroids per routine care immediately prior to CLR 131 dosing is acceptable.
Exclusion Criteria:
- Patients receiving active treatment for central nervous system metastases or those that are likely to require active treatment during anticipated participation in this trial. Patients with stable brain metastases treated with steroids may enroll at the investigator's discretion
- For solid tumor and lymphoma patients only, central nervous system involvement unless previously treated with surgery, systemic therapy, or radiotherapy with the patient neurologically stable. Patients with metastatic brain tumors that have been previously treated are allowed, provided the patient is neurologically stable (determined at the investigator's discretion).
- Antitumor therapy or investigational therapy, within 2 weeks of dosing. For certain types of radiation (craniospinal, total abdominal, whole lung [spot irradiation to skull-based metastases is not considered craniospinal radiation for the purposes of this study]), at least 3 months must have elapsed. No washout is required for palliative focal radiation. NOTE: Patients participating in non-interventional clinical trials (i.e., non-drug) are allowed to participate in this trial
- Patients previously treated with iodine-131 (131I)-MIBG who have already received a cumulative I-131 dose > 54 mCi/kg or who would exceed 54 mCi/kg by participating in this trial, are not eligible.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03478462
United States, California | |
Lucile Packard Children's Hospital | |
Palo Alto, California, United States, 94304 | |
United States, New York | |
Memorial Sloan Kettering Cancer Center | |
New York, New York, United States, 10065 | |
United States, North Carolina | |
Duke University | |
Chapel Hill, North Carolina, United States, 27708 | |
United States, Ohio | |
Cincinnati Children's Hospital Medical Center | |
Cincinnati, Ohio, United States, 45229 | |
United States, Texas | |
Texas Children's Hospital | |
Houston, Texas, United States, 77030 | |
United States, Wisconsin | |
University of Wisconsin Hospital and Clinics | |
Madison, Wisconsin, United States, 53792 | |
Australia, New South Wales | |
Children's Hospital at Westmead | |
Westmead, New South Wales, Australia, 2145 | |
Canada, Ontario | |
Hospital for Sick Children | |
Toronto, Ontario, Canada, M5G1X8 |
Study Director: | Jarrod Longcor | Cellectar Biosciences |
Responsible Party: | Cellectar Biosciences, Inc. |
ClinicalTrials.gov Identifier: | NCT03478462 |
Other Study ID Numbers: |
DCL-17-001 |
First Posted: | March 27, 2018 Key Record Dates |
Last Update Posted: | May 17, 2023 |
Last Verified: | February 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
medulloblastoma ependymoma high-grade glioma glioblastoma DIPG diffuse-intrinsic pontine glioma ATRT atypical teratoid rhabdoid tumor PNET primitive neuroectodermal tumor gliosarcoma gliomatosis cerebri neuroblastoma |
rhabdomyosarcoma Ewing sarcoma osteosarcoma DSRCT desmoplastic small round cell tumor sarcoma malignant germ cell tumor synovial sarcoma rare cancer Wilms tumor lymphoma Hodgkin Lymphoma Non-Hodgkin Lymphoma |
Lymphoma Neoplasms Sarcoma Brain Neoplasms Neuroblastoma Osteosarcoma Rhabdomyosarcoma Sarcoma, Ewing Neoplasms by Histologic Type Lymphoproliferative Disorders Lymphatic Diseases Immunoproliferative Disorders Immune System Diseases Neoplasms, Connective and Soft Tissue Central Nervous System Neoplasms |
Nervous System Neoplasms Neoplasms by Site Brain Diseases Central Nervous System Diseases Nervous System Diseases Neuroectodermal Tumors, Primitive, Peripheral Neuroectodermal Tumors, Primitive Neoplasms, Neuroepithelial Neuroectodermal Tumors Neoplasms, Germ Cell and Embryonal Neoplasms, Glandular and Epithelial Neoplasms, Nerve Tissue Neoplasms, Bone Tissue Neoplasms, Connective Tissue Myosarcoma |