Identification of Patients With Variants in TPMT and Dose Reduction Reduces Hematologic Events During Thiopurine Treatment of Inflammatory Bowel Disease

BACKGROUND & AIMS

More than 20% of patients with inflammatory bowel disease (IBD) discontinue thiopurine therapy because of severe adverse drug reactions (ADRs); leukopenia is one of the most serious ADRs. Variants in the gene encoding thiopurine S-methyltransferase (TPMT) alter its enzymatic activity, resulting in higher levels of thiopurine metabolites, which can cause leukopenia. We performed a prospective study to determine whether genotype analysis of TPMT before thiopurine treatment, and dose selection based on the results, affects the outcomes of patients with IBD.

METHODS

In a study performed at 30 Dutch hospitals, patients were assigned randomly to groups that received standard treatment (control) or pretreatment screening (intervention) for 3 common variants of TPMT (TPMT*2, TPMT*3A, and TPMT*3C). Patients in the intervention group found to be heterozygous carriers of a variant received 50% of the standard dose of thiopurine (azathioprine or 6-mercaptopurine), and patients homozygous for a variant received 0%-10% of the standard dose. We compared, in an intention-to-treat analysis, outcomes of the intervention (n = 405) and control groups (n = 378) after 20 weeks of treatment. Primary outcomes were the occurrence of hematologic ADRs (leukocyte count < 3.0*10(9)/L or reduced platelet count < 100*10(9)/L) and disease activity (based on the Harvey-Bradshaw Index for Crohn's disease [n = 356] or the partial Mayo score for ulcerative colitis [n = 253]).

RESULTS

Similar proportions of patients in the intervention and control groups developed a hematologic ADR (7.4% vs 7.9%; relative risk, 0.93; 95% confidence interval, 0.57-1.52) in the 20 weeks of follow-up evaluation; the groups also had similar mean levels of disease activity (P = .18 for Crohn's disease and P = .14 for ulcerative colitis). However, a significantly smaller proportion of carriers of the TPMT variants in the intervention group (2.6%) developed hematologic ADRs compared with patients in the control group (22.9%) (relative risk, 0.11; 95% confidence interval, 0.01-0.85).

CONCLUSIONS

Screening for variants in TPMT did not reduce the proportions of patients with hematologic ADRs during thiopurine treatment for IBD. However, there was a 10-fold reduction in hematologic ADRs among variant carriers who were identified and received a dose reduction, compared with variant carriers who did not, without differences in treatment efficacy. ClinicalTrials.gov number: NCT00521950.

Oral versus im administration of high-dose medroxyprogesterone acetate in pretreated patients with advanced breast cancer

In a multicenter trial, 123 patients with advanced breast cancer who had been treated with tamoxifen and/or chemotherapy were randomized to receive medroxyprogesterone acetate (MPA) orally 300 mg X 3 daily or im 500 mg daily for 4 weeks and 500 mg X 2 weekly thereafter. All case histories were reviewed extramurally by the criteria of the International Union Against Cancer. Five and 11 patients were not eligible and evaluable for response, respectively. Pretreatment characteristics were well balanced in both treated groups. Twenty-five of all 107 (23%) evaluable patients achieved an objective remission, whereas in a further 15% the disease became stable after previous progression. Results in both treatment arms did not differ significantly. The median duration of objective remission was 12 and 14 months for orally and im treated patients, respectively (P greater than 0.10). No statistically significant differences in the survival times of orally and im treated patients were found. Pretreatment characteristics positively correlated with an objective remission during MPA therapy in both groups were age greater than 50 years (P less than 0.02) and no previous chemotherapy (P less than 0.01). Toxicity included an increase in body weight, cushingoid effects, muscle cramps, and tremors in both groups. In four patients on im therapy, local infections developed. Mean serum MPA levels reached values above 100 ng/ml in nine orally and eight im treated patients (P greater than 0.10), and neither differed significantly in the patients responding to or failing therapy. In both MPA arms, plasma cortisol levels were suppressed. The drop in plasma cortisol levels was more pronounced in patients with objective remissions than in patients who failed (P = 0.04). In conclusion, oral and im MPA in the given doses had similar activity. Im administration of MPA should be reserved for patients not able to take oral medication.