Dataset Information

EPCT-09. CLR 131 IN PATIENTS WITH RELAPSED OR REFRACTORY PEDIATRIC MALIGNANCIES

ABSTRACT: Abstract

BACKGROUND

CLR 131 is a novel targeted radiotherapeutic that exploits the selective uptake and retention of phospholipid ethers by malignant cells. CLR 131 selectively delivers radiation to malignant tumor cells, thus minimizing radiation exposure to normal tissues.

OBJECTIVE

CLR 131 is being examined in a Phase 1 trial, CLOVER-2 (NCT03478462), to determine the safety, tolerability, and initial efficacy of CLR 131 in children and adolescents with relapsed/refractory malignancies.

METHODS

Eligibility criteria include children with relapsed or refractory solid tumors or malignant brain tumors for which there are no standard treatment options with curative potential. Subjects must be between ages 2 and 21 with no limit to the number of prior therapies. CLR 131 is administered as a single infusion in escalating doses beginning at 15 mCi/m2. Adverse events (AEs) are graded by NCI-CTCAE v5.

RESULTS

As of 10Jan2020, four subjects with brain tumors have received CLR 131; one at 15 mCi/m2 and three at 30 mCi/m2. Diagnoses included DIPG (2), glioblastoma (1), and medulloblastoma (1). Median age is 13 years (range 10–15) and patients received a median of two prior therapies (range 1 to 8). There were no treatment emergent AEs at the 15 mCi/m2 dose level attributed to CLR 131 by the investigator. Assessment of the 30 mCi/m2 dose level is ongoing.

CONCLUSIONS

CLR 131 is a unique, first in class targeted radiotherapeutic for pediatric malignancies. Preliminary data shows an acceptable and expected safety profile in this patient population. Dose escalation to determine the highest tolerated dose is ongoing.

SUBMITTER: Puccetti D

PROVIDER: S-EPMC7715900 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Project description:INTRODUCTION:CLR1404 is a theranostic molecular agent that can be radiolabeled with 124I (CLR 124) for positron emission tomography (PET) imaging, or 131I (CLR 131) for single-photon emission computed tomography (SPECT) imaging and targeted radionuclide therapy. This pilot study evaluated a pretreatment dosimetry methodology in a triple-negative breast cancer patient who was uniquely enrolled in both a CLR 124 PET imaging clinical trial and a CLR 131 therapeutic dose escalation clinical trial. MATERIALS AND METHODS:Three-dimensional PET/CT images were acquired at 1, 3, 24, 48, and 120?h postinjection of 178?MBq CLR 124. One month later, pretherapy 2D whole-body planar images were acquired at 0.25, 5, 24, 48, and 144?h postinjection of 370?MBq CLR 131. Following the therapeutic administration of 1990?MBq CLR 131, 3D SPECT/CT images were acquired at 74, 147, 334, and 505?h postinjection. The therapeutic CLR 131 voxel-level absorbed dose was estimated from PET (RAPID PET) and SPECT (RAPID SPECT) images using a Geant4-based Monte Carlo dosimetry platform called RAPID (Radiopharmaceutical Assessment Platform for Internal Dosimetry), and region of interest (ROI) mean doses were also estimated using the OLINDA/EXM software based on PET (OLINDA PET), SPECT (OLINDA SPECT), and planar (OLINDA planar) images. RESULTS:The RAPID PET and OLINDA PET tracer-predicted ROI mean doses correlated well (m???0.631, R2 ? 0.694, p???0.01) with both the RAPID SPECT and OLINDA SPECT therapeutic mean doses. The 2D planar images did not have any significant correlations. The ROI mean doses differed by -4% to -43% between RAPID and OLINDA/EXM, and by -19% to 29% between PET and SPECT. The 3D dose distributions and dose volume histograms calculated with RAPID were similar for the PET/CT and SPECT/CT. CONCLUSIONS:This pilot study demonstrated that CLR 124 pretreatment PET images can be used to predict CLR 131 3D therapeutic dosimetry better than CLR 131 2D planar images. In addition, unlike OLINDA/EXM, Monte Carlo dosimetry methods were capable of accurately predicting dose heterogeneity, which is important for predicting dose-response relationships and clinical outcomes.