Correlation between PI3K/PTEN/AKT/mTOR pathway genetic variations and clinical outcome in patients with squamous cell carcinoma of the head and neck receiving cetuximab-docetaxel treatment.

Abstract

5572 Background: The PI3K/PTEN/AKT/mTOR pathway is one of the most targeted in human cancers and alterations in the axis are frequent events in squamous cell carcinoma of the head and neck (HNSCC). Specific genetic variations in this pathway have been associated with variation in recurrence, survival and response in lung cancer and esophageal cancer. The aim of this study was to determine whether single nucleotide nucleotide polymorphisms (SNPs) in AKT1, AKT2, FRAP1, PI3KCA and PTEN identified in other cancers were associated with treatment response and clinical outcome in patients with HNSCC. Methods: Genomic DNA was extracted from FFPE tissue specimens of 45 patients with recurrent or initially metastatic HNSCC who received a combined treatment with docetaxel and cetuximab in a phase II study. Eleven single SNPs in the genes AKT1, AKT2, FRAP1 (mTOR), PIK3CA and PTEN were genotyped by means of Real Time PCR system or by direct sequencing and analysed for association with response to therapy and survival. Results: None of the SNPs was related to treatment response. Two SNPs (AKT2:rs8100018 and PTEN:rs12569998) were associated with variation in progression risk. The AKT2:rs8100018 homozygous variant resulted in increased risk, with a HR of 4.83 (95% CI, 1.11-21.03) and the PTEN:rs12569998 homozygous variant in an increased risk, with a HR of 2.36 (95% CI, 1.24-4.50). AKT2:rs8100018 and PTEN:rs12569998 genetic variation had an additive effect on risk of tumor progression. The AKT2:rs8100018 homozygous variant was significantly associated with overall survival (OS) with HR of 3.57 (95% CI, 1.06-12.00) while presence of one of the two variant alleles of AKT1:rs3803304 with a lower risk of death (HR: 0.51; 95% CI, 0.27-0.97). Conclusions: We found significant associations between common genetic variants in the PI3K/PTEN/AKT/mTOR pathway and outcome in patients with HNSCC. Despite the small sample size, patient cohort and treatment were homogeneous. As a consequence, evaluation of SNPs as a host factor may be considered in addition to tumor-specific mutations for personalized treatment development.