Pharmacogenomics of the Efficacy and Safety of Colchicine in COLCOT
The data underlying this article cannot be shared publicly to preserve the privacy of study participants; however, the data are available from the corresponding authors upon reasonable requests. The analytic methods and study materials may be made available to other researchers for purposes of reproducing the results or replicating the procedure. Summary statistics are available publicly for download and visualization via PheWEB at URL: http://statgen.org/pheweb/colcot . The COLCOT clinical trial was registered at URL: https://www.clinicaltrials.gov under the unique identifier NCT02551094. The study protocol was approved by the Montreal Heart Institute research ethics committee and complies with the Declaration of Helsinki. Written informed consent was obtained from all participating subjects. Full Methods are available in the Data Supplement of the article. 

There were 1522 participants included in the pharmacogenomic analysis of COLCOT of which 767 were randomized to colchicine and 755 to placebo (Figure I in the Data Supplement ). The baseline characteristics of patients according to the study treatment groups are shown in Table . The mean age of participants was 60.9 years and 81.3% were male. The COLCOT study primary cardiovascular end point occurred in 6.2% of patients who consented to the pharmacogenomic substudy, as compared to 6.3% of those in the main trial ( P =0.86; Table I in the Data Supplement ). Gastrointestinal adverse events occurred in 23.4% of the pharmacogenomic study population, as compared to 17.6% of the COLCOT trial participants ( P =1.8×10 −7 ). Genetic Determinants of Cardiovascular Efficacy With Colchicine The pharmacogenomic analyses of the primary cardiovascular efficacy end point were limited to the 702 participants randomized to colchicine who used the study drug with at least 80% compliance in the first 6 months of treatment. Of those, 39 patients had an event. The prespecified analysis for the ATP binding cassette subfamily B member 1 gene ( ABCB1 ) variant rs1045642 and the CYP3A4 (cytochrome P450 family 3 subfamily A member 4) metabolizer phenotype was not associated with the primary cardiovascular efficacy end point ( P =0.77 and P =0.91, respectively), and none of the tested genetic variants passed the genome-wide association study (GWAS) significance threshold ( P <5×10 −8 ; Figure IIA in the Data Supplement ). However, the GWAS analysis had limited power, and negative results should be interpreted with care. The sex-stratified GWAS with 576 male participants also did not provide any GWAS-significant findings (Figure IIB in the Data Supplement ), however, there was some interest for the top signal on chromosome 9 at rs10811106 ( P =5.8×10 −8 ) near the stabilizer of axonemal microtubules 1 ( SAXO1 ) gene (also known as FAM154A ), as it encodes the stabilizer of axonemal microtubules 1 (Figure IIIB in the Data Supplement ). Genetic Determinants of Gastrointestinal Adverse Events With Colchicine There were 767 participants randomized to colchicine who were included in the genetic analyses for gastrointestinal adverse events, of those, 187 had a gastrointestinal event. The ABCB1 rs1045642 variant and the CYP3A4 metabolizer phenotype were not associated with gastrointestinal adverse events ( P =0.97 and P =0.31, respectively). We found 22 genetic variants significantly associated with gastrointestinal events at 2 loci located on chromosomes 6 and 10 (Figure). The most significant association on chromosome 6 was the intergenic variant rs6916345 ( P =7.41×10 −9 ). When conditioning on rs6916345, no additional genetic variants remained significant at P <5×10 −8 in the region, and rs6916345 had the highest probability of being causal by CAVIAR analysis ( Data Supplement ). The minor allele (A) was associated with gastrointestinal events in the colchicine group (hazard ratio [HR], 1.89 [95% CI, 1.52–2.35], P =7.41×10 −9 ) with an estimated effect in the placebo group of HR=1.30 (95% CI, 1.04–1.62; P =0.02). The effect appeared to be mostly driven by the occurrence of diarrhea (Table II in the Data Supplement ). The interaction term between rs6916345 and colchicine treatment was significant ( P =2.96×10 −8 ; Table ). Individuals with the AA genotype represented 25% of the trial population. Gastrointestinal adverse events were reported by 36.9% of AA patients in the colchicine group compared with 18.6% in the placebo group (HR, 2.42 [95% CI, 1.57–3.72], P =5.77×10 −5 ; Table ). We found evidence of colocalization of the locus with Crohn disease (Material and Figure V in the Data Supplement ). The risk allele (A) at rs6916345 was previously associated with Crohn disease (odds ratio, 1.07, P =3.1×10 −5 ). The most significant association at the chromosome 10 locus was at rs10128117 located in intron 2 of the selenophosphate synthetase 1 gene ( SEPHS1 ). However, because this variant is triallelic and was imputed as biallelic, we report the findings based on variant, rs74795203, in strong linkage disequilibrium, located in intron 4 of the gene (Figure IVB in the Data Supplement ). The G allele of variant rs74795203 was associated with gastrointestinal events with an HR of 2.51 (95% CI, 1.82–3.47; P =2.70×10 −8 ) with an estimated effect in the placebo group of HR of 0.71 (95% CI, 0.46–1.09; P =0.11). The interaction term between rs74795203 and colchicine treatment was significant ( P =3.13×10 −6 ; Table ). When conditioning on rs10128117 or rs74795203, no additional genetic variants remained significant at P <5×10 −8 . Individuals with the AG or GG genotype at rs74795203 represented 13% of the trial population. Gastrointestinal adverse events were reported by 47.1% of patients with the AG or GG genotype in the colchicine arm compared with 18.9% in the placebo arm (HR, 3.98 [95% CI, 2.24–7.07], P =2.33×10 −6 ; Table ). The GWAS limited to 622 male participants did not identify additional association signals. 

The pharmacogenomic analyses of the primary cardiovascular efficacy end point were limited to the 702 participants randomized to colchicine who used the study drug with at least 80% compliance in the first 6 months of treatment. Of those, 39 patients had an event. The prespecified analysis for the ATP binding cassette subfamily B member 1 gene ( ABCB1 ) variant rs1045642 and the CYP3A4 (cytochrome P450 family 3 subfamily A member 4) metabolizer phenotype was not associated with the primary cardiovascular efficacy end point ( P =0.77 and P =0.91, respectively), and none of the tested genetic variants passed the genome-wide association study (GWAS) significance threshold ( P <5×10 −8 ; Figure IIA in the Data Supplement ). However, the GWAS analysis had limited power, and negative results should be interpreted with care. The sex-stratified GWAS with 576 male participants also did not provide any GWAS-significant findings (Figure IIB in the Data Supplement ), however, there was some interest for the top signal on chromosome 9 at rs10811106 ( P =5.8×10 −8 ) near the stabilizer of axonemal microtubules 1 ( SAXO1 ) gene (also known as FAM154A ), as it encodes the stabilizer of axonemal microtubules 1 (Figure IIIB in the Data Supplement ). 

There were 767 participants randomized to colchicine who were included in the genetic analyses for gastrointestinal adverse events, of those, 187 had a gastrointestinal event. The ABCB1 rs1045642 variant and the CYP3A4 metabolizer phenotype were not associated with gastrointestinal adverse events ( P =0.97 and P =0.31, respectively). We found 22 genetic variants significantly associated with gastrointestinal events at 2 loci located on chromosomes 6 and 10 (Figure). The most significant association on chromosome 6 was the intergenic variant rs6916345 ( P =7.41×10 −9 ). When conditioning on rs6916345, no additional genetic variants remained significant at P <5×10 −8 in the region, and rs6916345 had the highest probability of being causal by CAVIAR analysis ( Data Supplement ). The minor allele (A) was associated with gastrointestinal events in the colchicine group (hazard ratio [HR], 1.89 [95% CI, 1.52–2.35], P =7.41×10 −9 ) with an estimated effect in the placebo group of HR=1.30 (95% CI, 1.04–1.62; P =0.02). The effect appeared to be mostly driven by the occurrence of diarrhea (Table II in the Data Supplement ). The interaction term between rs6916345 and colchicine treatment was significant ( P =2.96×10 −8 ; Table ). Individuals with the AA genotype represented 25% of the trial population. Gastrointestinal adverse events were reported by 36.9% of AA patients in the colchicine group compared with 18.6% in the placebo group (HR, 2.42 [95% CI, 1.57–3.72], P =5.77×10 −5 ; Table ). We found evidence of colocalization of the locus with Crohn disease (Material and Figure V in the Data Supplement ). The risk allele (A) at rs6916345 was previously associated with Crohn disease (odds ratio, 1.07, P =3.1×10 −5 ). The most significant association at the chromosome 10 locus was at rs10128117 located in intron 2 of the selenophosphate synthetase 1 gene ( SEPHS1 ). However, because this variant is triallelic and was imputed as biallelic, we report the findings based on variant, rs74795203, in strong linkage disequilibrium, located in intron 4 of the gene (Figure IVB in the Data Supplement ). The G allele of variant rs74795203 was associated with gastrointestinal events with an HR of 2.51 (95% CI, 1.82–3.47; P =2.70×10 −8 ) with an estimated effect in the placebo group of HR of 0.71 (95% CI, 0.46–1.09; P =0.11). The interaction term between rs74795203 and colchicine treatment was significant ( P =3.13×10 −6 ; Table ). When conditioning on rs10128117 or rs74795203, no additional genetic variants remained significant at P <5×10 −8 . Individuals with the AG or GG genotype at rs74795203 represented 13% of the trial population. Gastrointestinal adverse events were reported by 47.1% of patients with the AG or GG genotype in the colchicine arm compared with 18.9% in the placebo arm (HR, 3.98 [95% CI, 2.24–7.07], P =2.33×10 −6 ; Table ). The GWAS limited to 622 male participants did not identify additional association signals. 

In this pharmacogenomic study of the randomized, placebo-controlled COLCOT trial, genetic variants were found to be associated with gastrointestinal events in patients treated with colchicine, offering insights into the biological mechanisms underlying the tolerability of treatment with colchicine. Although the signal did not reach the significance threshold, we have found an interesting genetic region on chromosome 9 in the prespecified analysis in males that is possibly associated with the cardiovascular benefits of colchicine. The locus is particularly interesting as it spans the SAXO1 gene, and it colocalizes with the expression of the HAUS augmin like complex subunit 6 ( HAUS6 ) gene which is involved in microtubule generation from existing microtubules and in kinetochore-microtubule attachment and central spindle formation during anaphase. The cardiovascular event risk allele at the leading variant reduces HAUS6 expression, and it may possibly interact with the effects of colchicine on tubulin binding and microtubule polymerization. However, replication of this locus in future cardiovascular studies with colchicine is necessary. The genome-wide analysis of gastrointestinal adverse events found 2 associated regions. The first region on chromosome 6 is particularly appealing as it colocalizes with a previously identified locus for Crohn disease. The risk allele of the lead variant at this locus was previously associated with Crohn disease risk and with reticulocyte counts and hemoglobin concentrations, which are common extraintestinal complication of Crohn disease. The second genetic locus on chromosome 10 overlaps the SEPHS1 , which encodes an enzyme that synthesizes selenophosphate from selenide and ATP. We found evidence of colocalization of the region with expression of SEPHS1 , with correlation between the gastrointestinal disorder risk allele and lower SEPHS1 gene expression. Despite the relatively small proportion of participants who consented to take part in the pharmacogenomic substudy of COLCOT (32%), we have found significant and credible association signals predictive of gastrointestinal events with colchicine use. There may be volunteer bias in the pharmacogenomic subgroup compared with the main trial population, and we observed a lower occurrence of deaths, possibly attributable to the fact that not all patients were recruited into the pharmacogenomic substudy at the baseline visit. This may have contributed to reducing the statistical power for detecting genetic association signals with the primary cardiovascular end point which included cardiovascular death. We also noted an overrepresentation of patients who reported suffering from gastrointestinal disorders during the course of the trial from both the colchicine and the placebo arm. This could be due to correlation between patient willingness to participate and to share information on milder gastrointestinal adverse events. We do not expect that this observation had an impact on the pharmacogenomic findings with gastrointestinal events, as the 2 genetic association signals identified were strong and had strong interaction effects with colchicine treatment. Because this study was a post hoc investigation, these results are considered as hypothesis-generating, and they will have to be replicated before using the information for clinical decision-making. Colchicine is used throughout the world for indications of gout, familial Mediterranean fever, pericarditis, and, since the COLCOT trial, for secondary cardiovascular prevention. There are other ongoing and planned clinical trials designed to assess the cardiovascular benefits of colchicine where it may be possible to replicate the findings if genetic material is collected. Reliance on observational studies and registries to conduct replication studies will become an option as the long-term use of colchicine for the prevention of secondary cardiovascular disease gains in popularity in the coming years. Shorter-term use of colchicine for the treatment of gout could provide useful data for replication of the genetic variants associated with gastrointestinal events. In conclusion, in the present pharmacogenomic study of the COLCOT trial, we have found genetic variants associated with gastrointestinal events in patients treated with colchicine. Those findings will benefit from replication to confirm our observations that some patients may have genetic predispositions to lower tolerability of treatment with colchicine. 

We acknowledge the technical support of Diane Valois and Isabelle Fillion for the genotyping work and of Yannik Couture and Sylvain Versailles for blood and DNA sample preparation. We thank the patients and staff who supported this study. 

This work was supported by the Health Collaboration Acceleration Fund from the Government of Quebec (to Dr Tardif). M.-A. Legault is supported by a Frederick Banting and Charles Best Canada Graduate Scholarship Doctoral Award from the Canadian Institutes of Health Research (CIHR). Dr Tardif holds the Canada Research Chair in Personalized Medicine and the Université de Montréal endowed research chair in atherosclerosis. Dr Dubé holds the Canada Research Chair in Precision Medicine Data Analysis. Dr Berry is supported by the British Heart Foundation (RE/18/6134217). Dr de Denus holds the Université de Montréal Beaulieu-Saucier Chair in Pharmacogenomics. The funding sources had no role in study design, conduct, or analyses. 

Dr Dubé reports grants from the Government of Quebec during the conduct of the study; personal fees from Dalcor, personal fees and other from GlaxoSmithKline, other from AstraZeneca, other from Pfizer, other from Servier, other from Sanofi, outside the submitted work; in addition, Dr Dubé has a patent Methods for Treating or Preventing Cardiovascular Disorders and Lowering Risk of Cardiovascular Events issued to Dalcor, no royalties received, a patent Genetic Markers for Predicting Responsiveness to Therapy with HDL-Raising or HDL Mimicking Agent issued to Dalcor, no royalties received, and a patent Methods for using low-dose colchicine after myocardial infarction with royalties paid to Invention assigned to the Montreal Heart Institute. Dr Tardif reports grants from the Government of Quebec, grants from Canadian Institutes of Health Research, grants from Montreal Heart Institute Foundation during the conduct of the study; grants from Amarin, grants and personal fees from Astra Zeneca, grants, personal fees and other from Dalcor, grants from Esperion, grants from Ionis, grants and personal fees from Sanofi, grants and personal fees from Servier, grants from RegenXBio, outside the submitted work; in addition, Dr Tardif has a patent Genetic markers for predicting responsiveness to therapy with HDL-raising or HDL mimicking agent pending, a patent Methods for using low-dose colchicine after myocardial infarction pending to Invention assigned to the Montreal Heart Institute, and a patent Methods of treating a coronavirus infection using Colchicine pending. Dr Waters reports personal fees from Pharmascience, outside the submitted work; Dr Kouz reports personal fees and other from Medtronic, grants, personal fees and other from Sanofi, other from Johnson & Johnson, personal fees and other from Amgen, grants, personal fees and other from Astrazeneca, grants, personal fees and other from Novartis, other from Celgene, other from Biogen, other from Gilead, other from Roche, other from Boston Scientific, personal fees and other from Bausch Health, other from GSK, personal fees and other from BMS, other from TG Therapeutics, other from Becton Dickinson, other from Spectrum Pharmaceuticals, personal fees from Merck, personal fees from Eli Lilly, personal fees from Pfizer, personal fees from Bayer, grants and personal fees from Boehringer-Ingelheim, personal fees from Servier, grants from Esperion, grants from Dalcor Pharmaceuticals, grants from Eisai, grants from Amarin Pharma, grants from Theracos, outside the submitted work; Dr Maggioni reports personal fees from Bayer, personal fees from DalCor, personal fees from Novartis, outside the submitted work; Dr Diaz reports grants from Montreal Health Innovations Coordinating Center, during the conduct of the study; grants from Dalcor, grants from Population Health Research Institute, outside the submitted work; Dr Berry reports that the University of Glasgow has received research and consultancy support for work done by CB with AstraZeneca, Abbott Vascular, DalCor, GSK, Heartflow, Menarini and Novartis. Dr Koenig reports personal fees from AstraZeneca, personal fees from Novartis, personal fees from Pfizer, personal fees from The Medicines Company, personal fees from DalCor, personal fees from Kowa, personal fees from Amgen, personal fees from Corvidia, personal fees from Daiichi-Sankyo, personal fees from Berlin-Chemie, personal fees from Sanofi, personal fees from Bristol-Myers Squibb, grants and nonfinancial support from Singulex, grants and nonfinancial support from Abbott, grants and nonfinancial support from Roche Diagnostics, grants and nonfinancial support from Beckmann, outside the submitted work; Dr Lopez-Sendon reports grants from Merk, grants from Pfizer, grants from Sanofi, grants from Amgen, grants from Boehringer Ingelheim, outside the submitted work; Dr Kiwan reports personal fees from Bayer, personal fees from Servier, personal fees from Novartis, personal fees from Astra Zeneca, personal fees from Bristol-Myers Squibb, personal fees from Roche, personal fees from Pfizer, outside the submitted work; Dr Rhainds reports personal fees from DalCor Pharmaceuticals, outside the submitted work; Dr Bouabdallaoui reports personal fees from AstraZeneca, outside the submitted work; Dr de Denus reports grants from Pfizer, AstraZeneca, Roche Molecular Science, and DalCor. Dr L’Allier reports personal fees from Pharmascience, personal fees from Philips, outside the submitted work; Dr Roubille reports grants, personal fees and nonfinancial support from Air Liquide, grants and personal fees from Abbott, personal fees from Vifor, grants and personal fees from Novartis, personal fees from Servier, personal fees from Abiomed, personal fees from Zoll, grants and personal fees from AstraZeneca, personal fees from Medtronic, personal fees from Resmed, from LVL, Eole, personal fees from Pfizer, outside the submitted work. The other authors report no conflicts. 

Online Methods and Results Online Tables I–IV Online Figures I–V References – 

