Laurent Chouchana

About 15% to 28% of patients treated with thiopurines experienced adverse drug reactions, such as haematological and hepatic toxicities. Some of these related to the polymorphic activity of the thiopurine S‐methyltransferase (TPMT), the key detoxifying enzyme of thiopurine metabolism. We report here a case of thiopurine‐induced ductopenia with a comprehensive pharmacological analysis on thiopurine metabolism. A 34‐year‐old woman, with a medical history of severe systemic lupus erythematosus with recent introduction of azathioprine therapy, presented with mild fluctuating transaminase blood levels consistent with a hepatocellular pattern, which evolved to a cholestatic pattern over the next weeks. A blood thiopurine metabolite assay revealed low 6‐thioguanine nucleotides (6‐TGN) level and a dramatically increased 6‐methylmercaptopurine ribonucleotides (6‐MMPN) level, together with an unfavourable [6‐MMPN:6‐TGN] metabolite ratio and a high TPMT activity. After a total of about 6 months of thiopurine therapy, a transjugular liver biopsy revealed a ductopenia, and azathioprine discontinuation led to further clinical improvement. In line with previous reports from the literature, our case supports the fact that ductopenia is a rare adverse drug reaction of azathioprine. The mechanism of reaction is unknown but may involve high 6‐MMPN blood level, due to unusual thiopurine metabolism (switched metabolism). Early therapeutic drug monitoring with measurement of 6‐TGN and 6‐MMPN blood levels may help physicians to identify patients at risk of similar duct injury.

Objectives Cytomegalovirus (CMV) is the leading cause of congenital infection worldwide. Reference anti-CMV treatment is valganciclovir/ganciclovir, which is contraindicated in pregnancy given questions about teratogenicity. Methods We analysed reports from VigiBase, the world’s largest safety database, and performed a disproportionality analysis of adverse pregnancy outcomes associated with (val)ganciclovir compared with any other drugs or with (val)aciclovir as comparators. Results Among 3 104 984 reports related to childbearing-age women or to pregnancy topics, 6186 were exposed to (val)ganciclovir or (val)aciclovir including 251 adverse pregnancy outcomes with (val)ganciclovir (n = 34) or (val)aciclovir (n = 217). We did not evidence any increased reporting of any adverse pregnancy outcome [miscarriage, stillbirth, small weight for gestational age, preterm birth (<37 weeks of gestation)] or birth defects with (val)ganciclovir compared with the use of (val)aciclovir during pregnancy. Four cases of oesophageal and anorectal atresia were identified with (val)ganciclovir, which may be related to concomitant drugs/medical conditions and require further analyses. Conclusions These preliminary results require confirmation but suggest the possibility for trial evaluation of val(ganciclovir) in severe maternal or fetal CMV infections.

This case report describes a pharmacokinetic drug–drug interaction between crizotinib, a tyrosine kinase inhibitor, and sofosbuvir/velpatasvir, a direct‐acting antiviral drug, leading to cardiac toxicity. A 75‐year‐old man, with no cardiovascular history but a diagnosis of metastatic nonsmall cell lung cancer with mesenchymal–epithelial transition exon‐14 deletion and hepatitis C virus infection genotype 1A, received both crizotinib and sofosbuvir/velpatasvir. Crizotinib was well tolerated, but 1 week after sofosbuvir/velpatasvir initiation, the patient experienced bilateral lower‐limb oedema and class III New York Heart Association dyspnoea. We assumed that increased exposure to crizotinib could account for this cardiac toxicity. Drug causality was probable according to the Naranjo scale. We hypothesized a reciprocal interaction between crizotinib and velpatasvir, mediated by both cytochrome 3A4 (CYP3A4) and P‐glycoprotein (P‐gp). Clinicians should be aware of the risk of drug–drug interactions between direct‐acting antiviral agents that inhibit CYP3A4 (glecaprevir) and/or P‐gp (voxilaprevir, velpatasvir) and anticancer tyrosine kinase inhibitors that are mostly CYP3A4 and/or P‐gp substrates (gefitinib, afatinib, erlotinib, crizotinib, ceritinib, lorlatinib, brigatinib, capmatinib etc.).