# Re-Irradiation Plus Pembrolizumab: A Phase II Study for Patients with Recurrent Glioblastoma

Source: https://onco.cc/key-papers/paper-pembrolizumab-glioblastoma-clin-cancer-res-2025/  
OnCo record `paper-pembrolizumab-glioblastoma-clin-cancer-res-2025` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Phase 2 or 3 results paper on Pembrolizumab in Glioma & glioblastoma, in Clinical Cancer Research (2025), one of the most cited Europe PMC records with Pembrolizumab in its title.

## Summary

Purpose: Radiotherapy may enhance antitumor immune responses by several mechanisms, including induction of immunogenic cell death. We performed a phase 2 study of pembrolizumab with re-irradiation in patients with recurrent glioblastoma.

Patients and methods: Sixty patients with recurrent glioblastoma received pembrolizumab with re-irradiation alone (cohort A, bevacizumab-naïve; n = 30) or with bevacizumab continuation (cohort B, n = 30). Dual primary endpoints, including the overall response rate and overall survival (OS) at either 12 (OS-12; cohort A) or 6 months (OS-6; cohort B), were assessed per cohort relative to historic benchmarks. Paired paraffin-embedded formalin-fixed tumor samples were assessed for immunologic biomarkers by IHC using digital quantification and co-detection-by-indexing (CODEX).

Results: Study therapy was well tolerated, with most toxicities being grade ≤3. For cohort B, the primary endpoint of OS-6 was achieved (57%); however, survival was not improved for cohort A patients. The overall response rate was 3.3% and 6.7% for cohorts A and B, respectively. CODEX analysis of paired tumor samples from five patients revealed an increase of activated T cells in the tumor microenvironment after study therapy.

Conclusions: Compared with historic controls, re-irradiation plus pembrolizumab seemed to improve survival among bevacizumab-refractory patients but not among bevacizumab-naïve patients. CODEX revealed evidence of intratumoral infiltration of activated immune effector cells. A randomized, properly controlled trial of PD-1 blockade plus re-irradiation is warranted to further evaluate this regimen for bevacizumab-refractory patients, but alternative approaches are needed for bevacizumab-naïve patients.

Indexed on Europe PMC as PubMed record 39513953 (DOI 10.1158/1078-0432.ccr-24-1629). Its title names Pembrolizumab and its text names Glioma & glioblastoma; PubMed types it as a clinical trial report (Clinical Trial, Phase II). It was matched automatically to the idea "Neoadjuvant immunotherapy with surgical window for glioblastoma" and no figure has been checked by an editor.

## Fields

- Kind: Key paper
- Last checked: 2026-09-22
- Tags: europepmc-ingest
- Journal: Clinical Cancer Research
- Year: 2025
- DOI: 10.1158/1078-0432.ccr-24-1629
- Authors: Iwamoto FM, Tanguturi SK, Nayak L, et al.
- What it means: One of the most cited trial reports Europe PMC returns for Pembrolizumab in Glioma & glioblastoma, so it is a natural first reading for anyone weighing the idea it is linked from. The record was linked automatically by title and abstract; read the abstract above and the paper itself before relying on any figure.
- Caveats: Matched by Pembrolizumab in the title and Glioma & glioblastoma in the title or abstract of the Europe PMC record; the summary reproduces the record's abstract and no figure has been verified against the full paper.; Chosen as a phase 2 or 3 report by the record's publication type or its own wording, not by reading the paper.

## Sources

- Clin Cancer Res 2025: https://doi.org/10.1158/1078-0432.ccr-24-1629
- PubMed: https://pubmed.ncbi.nlm.nih.gov/39513953/
- Europe PMC: https://europepmc.org/article/MED/39513953

## Connected records

- journals: [Clinical Cancer Research](https://onco.cc/journals/clinical-cancer-research/)
- ideas: [Neoadjuvant immunotherapy with surgical window for glioblastoma](https://onco.cc/ideas/idea-neoadjuvant-io-glioblastoma/)

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