Single-Nucleotide Polymorphisms in TAOK3 Are Associated With High Opioid Requirement for Pain Management in Patients...

Different amounts of opioid are required for the relief of cancer pain in different individuals, raising the possibility that genetic factors play a role. We tested the hypothesis that genetic variations in the TAOK3 (TAO kinase 3, encoding serine/threonine-protein kinase) explain some of the interindividual variations related to the morphine-equivalent daily dose (MEDD) in patients with cancer.

We selected two single-nucleotide polymorphisms (SNPs) in the TAOK3, reported earlier to associate with higher MEDD in postoperative pain based on genome-wide association study. We investigated their association with MEDD in Canadian patients with cancer (n = 110) admitted to a tertiary palliative care unit. SNPs analyzed were rs1277441 (C/T, C = minor allele) and rs795484 (A/G, A = minor allele).

Minor allele frequencies in our population were 0.29 (rs1277441) and 0.28 (rs795484). These SNPs were in perfect linkage disequilibrium (r² = 0.97). SNPs in TAOK3 showed a significant association with mean MEDD ≥800 mg. For rs795484, MEDD values ≥800 mg occurred in patients who were GG (7%), GA (18%), and AA (57%) (P = 0.004; Fisher's exact test); similar results were obtained for rs1277441. Homozygous variants for either SNP had received higher numbers of different opioids (P = 0.021).

In this cohort of patients with advanced cancer pain, TAOK3 SNPs were associated with opioid doses. This result supports the original findings from a GWAS in postoperative patients. The proportions of variant homozygotes (8.2% of patients) and their requirement for higher doses of opioids would appear potentially clinically important and should be validated in further studies.