brain-cancer

ABCB1 gene variants don't reliably predict temozolomide efficacy in glioblastoma, review finds.

Temozolomide (TMZ) is the standard chemotherapy for glioblastoma (GBM), but its efficacy is limited partly by the P-glycoprotein (ABCB1) efflux transporter at the blood-brain barrier. This systematic review of 4 studies (400+ patients) examined whether ABCB1 gene polymorphisms predict TMZ response…

Dan Manning

Dan Manning

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ABCB1 gene variants don't reliably predict temozolomide efficacy in glioblastoma, review finds.

ABCB1 gene variants don't reliably predict temozolomide efficacy in glioblastoma, review finds.

Temozolomide (TMZ) is the standard chemotherapy for glioblastoma (GBM), but its efficacy is limited partly by the P-glycoprotein (ABCB1) efflux transporter at the blood-brain barrier. This systematic review of 4 studies (400+ patients) examined whether ABCB1 gene polymorphisms predict TMZ response and survival.

Results were inconsistent: one early study reported a survival advantage for a specific ABCB1 genotype, but subsequent studies failed to replicate this. Common variants (1236C>T, 2677G>T/A, 3435C>T, 1199G>A) showed no robust association with clinical outcome. MGMT methylation and IDH status appear to be the dominant prognostic drivers.

ABCB1 polymorphisms are not ready for clinical use as predictive biomarkers in GBM, though the transporter may still be a relevant therapeutic target.

Key Findings

  • 4 studies with 400+ GBM patients analyzed in systematic review
  • One early study found ABCB1 C1236T C/C genotype associated with survival advantage
  • Subsequent studies failed to replicate this finding
  • Common ABCB1 variants showed no robust associations with OS or treatment response
  • MGMT methylation and IDH status dominate as prognostic factors

Implications

ABCB1 genotyping should not currently be used for TMZ treatment decision-making in GBM. Future research should focus on directly measuring ABCB1 function at the tumor-BBB interface rather than germline variants. Combining transporter genomics with tumor molecular profiling may improve predictions.

Caveats

Systematic review of limited studies (n=4); abstract-only. Small, heterogeneous studies reduce conclusion strength. Germline variants may not reflect intratumoral transporter expression. Review may have publication bias.

Source: Journal of cellular and molecular medicine — 2026-04-01

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