New PET tracer aims to spy on immune cells fighting cancer

NCT ID NCT04260256

Terminated Knowledge-focused Sponsor: CellSight Technologies, Inc. Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This pilot study tested whether a new PET imaging tracer called [18F]F-AraG could track immune T cells inside tumors of patients with advanced solid cancers who were receiving immunotherapy. Nine patients were enrolled to have PET scans and tumor biopsies before and after treatment. The goal was to see if changes in the tracer signal matched changes in immune cell levels in the tumor, which could eventually help doctors monitor treatment response without invasive biopsies.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: [18F]F-AraG (a radioactive tracer for PET scans)
What this could lead to: If successful, this imaging method could help doctors see whether immunotherapy is working in tumors without needing repeated biopsies.
What could go wrong: This was a very small pilot study (only 9 patients) that was terminated early, so results are limited. The tracer's ability to predict treatment benefit is still unproven.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

neoplasm

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

CORRELATE TRACER UPTAKE TO TCELL TUMOR INFILTRATION & CKIT BENEFIT

Contacts and locations

Locations

Oregon Health and Science University

Portland, Oregon, 97239, United States
Stanford University

Stanford, California, 94305, United States

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