Macroenzymes as a reason for aminotransferases flare in cystic fibrosis patients on CFTR modulators therapy - Report of three cases.

It has been shown that macro-ALT/macro-AST cause false increase of ALT/AST activity in standard laboratory testing. This short communication presents a group of cystic fibrosis subjects who developed aminotranferases flare a few months after initiation of CFTR modulators therapy. Patients did not present any clinical signs or symptoms of liver failure and differential examination did not show any underlying liver disease. All patients tested positive for macro-ALT and macro-AST. Despite increased and fluctuating ALT/AST activity in standard tests patients restarted CFTR modulators therapy with good clinical effect and do not present any other than hypertransaminasemia signs or symptoms of progressing liver disease. Our data shows that ALT/AST flare during CFTR modulators therapy may be related to macro-ALT/macro-AST, thus patients with high ALT/AST during CFTR modulators therapy should be tested for macro-ALT/macro-AST.

Increased aminotransferases do not necessarily mean hepatotoxicity of CFTR modulator therapy.

Aim of the study: The presence of macroenzymes may mimic treatment related hepatotoxicity. Material and methods: We present a female subject who developed high alanine aminotransferase (ALT)/aspartate aminotransferase (AST) activity during cystic fibrosis transmembrane regulator (CFTR) modulator therapy. Results: The differential work-up did not show any underlying liver disease. CFTR modulators were stopped with subsequent normalization and immediate rise of ALT/AST after modulators were restarted, which was interpreted as the presentation of CFTR modulator hepatotoxicity. Before permanent CFTR modulators' discontinuation the patient's blood was tested for the presence of macroALT/macroAST and the result was positive. The patient is continuing a CFTR modulator treatment that is being supervised using standard laboratory tests and a test detecting the presence of macroenzymes. At three subsequent measurements the tests showed the presence of macroenzymes. Conclusions: Our patient shows that increased ALT/AST during CFTR modulator therapy may be related to the induction of macroenzymes and not necessarily to hepatotoxicity. Patients with high ALT/AST activity should be considered for testing for the presence of macroenzymes.