Haematological toxicity presents a potentially life-threatening reduction in blood and bone marrow cells, elevating the likelihood of infection, anaemia, bleeding, and other adverse consequences. Various medications can induce haematological toxicity, with cancer treatment drugs exhibiting a notably high prevalence of such toxicity.
In a 2016 analysis, treatment data of patients undergoing PGx-guided treatment were compared to historical controls receiving fluoropyrimidines, a popular group of anti-cancer therapies. A genetic variant of the enzyme dihydropyrimidine dehydrogenase, responsible for metabolising fluoropyrimidines, was strongly linked to life-threatening toxicity. The study revealed a 73 percent toxicity rate among historical controls, which reduced to 28 percent with the implementation of PGx-guided treatment.
Furthermore, PGx had a life-saving impact, as the toxicity-related death rate in the control group was 10 percent, dropping to zero among those guided by PGx. Despite accounting for screening costs, the total treatment expenses were lower for patients who underwent PGx screening compared to those who did not.
Research from 2015 underscores the potential of PGx testing in enhancing safety for patients with inflammatory bowel disease (IBD). Approximately 20 percent of IBD patients discontinue treatment due to adverse events. Variants in the gene encoding thiopurine S-methyltransferase (TPMT) are linked to a severe adverse outcome, leukopenia. A study comparing 405 patients who underwent PGx testing for TPMT variants to 378 who did not found that while screening did not reduce the proportion of patients experiencing haematologic adverse drug reactions, genetic testing reduced the rate of adverse reactions tenfold among those in the test group who were identified and given a lower dose, without compromising treatment efficacy.
A more recent study determined that PGx-guided prescription of thiopurines in patients with inflammatory bowel syndrome did not result in additional healthcare costs.