NCT07057349

CSB-321 Ph 1 in Immunotherapy for the Treatment of Cancer

Phase 1 Multi-cohort Evaluation of [18F]CSB-321 PET Imaging in Participants Receiving Immunotherapy for the Treatment of Cancer

• Status: Not Yet Recruiting
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 40 (estimated)
• Sponsor: Cytosite Biopharma Inc. · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

Single-center with the option to expand to multi-center, international, open label, non-randomized, multiple-dose, multi-cohort study, in participants with metastatic or unresectable cancer. Eligible participants will receive an initial injection of \[18F\]CSB-321 followed by PET imaging prior to administration of the I-O therapy and a second and third injection post treatment each with PET imaging. The images will be analyzed for the distribution of radioactivity. Participants will be followed for adverse events up to 3-4 hours post injection. Available clinical, imaging, and histology data will be collected at follow-up to establish the disease progression for evaluation of \[18F\]CSB-321.

Detailed description

This single site, open label, non-randomized, multiple dose phase 1 study, in participants with metastatic cancer which can be treated with checkpoint inhibitor therapy or bi-specific immunological therapy. The primary safety objective is to test the safety of \[18F\]CSB-321 in participants with cancer. The primary efficacy and secondary objectives are to gain evidence in support of the hypothesis that \[18F\]CSB-321 uptake will correlate with tumoral response to treatment with the I-O therapy. \[18F\]CSB-321 PET imaging will be performed in participants with metastatic cancers that are planned to receive an I-O therapy for cancer treatment. Participants in cohort 1 can receive mono or combination I-O therapies which have FDA approval for the indication of use. They may also receive chemotherapy. Cohort 2 will receive only ipilimumab with nivolumab. Cohort 3 will be treated with tebentafusp-tebn monotherapy or combination I-O therapies. \[18F\]CSB-321 PET imaging will be acquired on one to three separate days: Up to 14 days prior to initial administration of I-O therapy and for cohorts 1 and 2, the next two doses will occur between Day 5 and 42 after initiation of checkpoint inhibitor (cycle 1, which occurs on day 0). For participants treated with tebentafusp-tebn (cohort 3), the second imaging session will take place on 24 hours after the third infusion. The third imaging will be performed 24 hours after the thirteenth Infusion. The available clinical and cross-sectional imaging data will be collected at 6 ± 2- months after initiation of I-O therapy. This follow up period is for collecting data to establish tumor growth and hence I-O therapy treatment efficacy. This will then be used to establish correlations with \[18F\]CSB-321 PET. The 6-month follow-up will be the timepoint used for these correlations. As the participants will be off the investigational treatment, this follow-up period for the 6-month visit is considered differently than the study period and hence AEs will not be collected during this period. See Adverse Event Reporting section 8.2.5 for more details. The optional excisional tumor biopsy will provide the most definitive information regarding the presence of granzyme B in the tumor. These excisional biopsies, when obtained, will be performed following \[18F\]CSB-321 PET imaging, to allow for correlative analysis.

Conditions

• Metastatic Cancer
• Unresectable Solid Tumor

Interventions

Type	Name	Description
DRUG	[18F]CSB-321	\[18F\]CSB-321 is a PET imaging agent that is bound to released granzyme B from T-cells

Timeline

• Start date: 2025-09-01
• Primary completion: 2027-09-01
• Completion: 2029-02-01
• First posted: 2025-07-09
• Last updated: 2025-07-09

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study