¹⁸F-DOPA-PET Detects Early Treatment Response in IDH-Mutant Glioma

Key Clinical Takeaways:

• Design/Population: This retrospective analysis included 20 patients with IDH1/2-mutant glioma (astrocytoma or oligodendroglioma) treated with IDH inhibitors through clinical trials or expanded access programs who underwent serial MRI and ¹⁸F-DOPA-PET imaging.
• Key Outcomes: Metabolic responses on ¹⁸F-DOPA-PET, including reductions in tumor-to-background ratios and metabolic tumor volume, were observed in half of patients and identified partial or complete responses not detected by standard MRI assessments, which classified disease as stable.
• Clinical Relevance: These findings support the use of ¹⁸F-DOPA-PET and advanced MRI sequences as complementary tools to standard RANO 2.0 MRI criteria for assessing treatment response and tumor control in IDH-mutant glioma.

Results from a real-world imaging analysis suggest that ¹⁸F-DOPA-PET and advanced MRI sequences may provide earlier indicators of treatment response than conventional MRI in patients with IDH-mutant glioma receiving IDH inhibitors.

“Small-molecule inhibitors targeting IDH1/2-mutant proteins have demonstrated benefit in IDH1/2-mutant gliomas,” stated Diego Prost, Pitié-Salpêtrière University Hospital, Paris, France, and coauthors. “However, responses assessed by conventional MRI measurements are infrequent, delayed, and difficult to interpret, highlighting the need for early biomarkers of treatment benefit.” 

In this study, researchers collected data from 20 patients with IDH 1/2-mutated astrocytoma (n = 8) or oligodendroglioma (n = 12) who received either ivosidenib (n = 4) or vorasidenib (n = 16) along with pre- and post-treatment MRI and ¹⁸F-DOPA-PET scans. MRI assessments incorporated 2D and 3D measurements on T2-weighted FLAIR and post-contrast T1 images, as well as perfusion and diffusion imaging. PET analyses included metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor-to-background ratios (TBRs). Response was evaluated using volumetric approaches, RANO 2.0 MRI criteria, and PET RANO 1.0 criteria and were compared with clinical outcomes.

At analysis, 50% of patients experienced significant reductions in ¹⁸F-DOPA-PET parameters (TBR_mean, TBR_max, and MTV). Using PET-based criteria, 9 patients achieved a partial response, and 1 patient achieved a complete response. Both volumetric MRI and standard 2D morphologic MRI assessments classified stable disease as the best response in all cases. PET response based on MTV reduction was associated with prolonged tumor control.

“These results highlight the potential of ¹⁸F-DOPA-PET and advanced MRI sequences as valuable complements to standard RANO 2.0 MRI evaluations for assessing treatment response in glioma patients undergoing IDHi therapy,” concluded Dr Prost et al. 

Source: 

Prost D, Nichelli L, Rozenblum L, et al. 18F-DOPA-PET and advanced MRI improve treatment response assessment in IDH1/2-mutant gliomas treated with IDH inhibitors. Clin Cancer Res. Published online: February 2, 2026. doi:10.1158/1078-0432.CCR-25-0279