P302 Faecal calprotectin and elastase concentrations in patients before and after treatment with CFTR modulators

Faecal calprotectin and pancreatic elastase-1 are two of the most common gastrointestinal tract (GI) markers measured in cystic fibrosis (CF) patients. We assessed the change in calprotectin and elastase levels after the initiation of CFTR modulators (mCFTR) in paediatric patients with CF. Samples of faecal calprotectin and elastase-1 were collected before and 3 months after the modulator onset (2 measurements) in 29 subjects: 21 (72%) received elexacaftor/tezacaftor/ivacaftor (ETI), 7 (24%) tezacaftor/ivacaftor (TI) and 1 (3%) lumacaftor/ivacaftor (LI). A decrease in calprotectin was observed in 22 cases (76%), while an increase was noted in 6 patients (21). In the ETI group, in 13/21 (62%) subjects calprotectin was above 50 µg/g before mCFTR. After 3 months, in all patients calprotectin values decreased. Additionally, in the ETI group in 12/13 (92%) patients calprotectin was below 50 µg/g. In the TI group with calprotectin above 50 µg/g before mCFTR (4 patients), in 2 patients calprotectin decreased, but not below normal value. The analysis showed a statistically significant difference in calprotectin measurements only in the ETI group (p < 0,001). Faecal elastase increased in 55% of patients. However, neither ETI nor TI patients showed an increase in elastase levels above 200 µg/g. The only patient on LI was pancreatic sufficient and, due to acute pancreatitis, the treatment was ceased. Our results show that mCFTR treatment in children with CF may influence the concentration of stool calprotectin and elastase. Further assessments are needed to test the clinical importance of these findings.