Lack of placental transfer of certolizumab pegol during pregnancy: results from CRIB, a prospective, postmarketing, pharmacokinetic study

Objectives There is a need for effective and safe treatment during pregnancy in women with chronic inflammatory diseases. This study evaluated placental transfer of certolizumab pegol (CZP), an Fc-free anti-tumour necrosis factor drug, from CZP-treated pregnant women to their infants. Methods CRIB was a pharmacokinetic (PK) study of women 30 weeks pregnant receiving commercial CZP for a locally approved indication (last dose 35 days prior to delivery). Blood samples were collected from mothers, umbilical cords and infants at delivery, and infants again at weeks 4 and 8 post-delivery. CZP plasma concentrations were measured with a highly sensitive and CZP-specific electrochemiluminescence immunoassay (lower limit of quantification 0.032 g/mL). Results Sixteen women entered and completed the study. Maternal CZP plasma levels at delivery were within the expected therapeutic range (median [range] 24.4 [5.0-49.4] g/mL). Of the 16 infants, 2 were excluded from the per-protocol set: 1 due to missing data at birth and 1 due to implausible PK data. Of the remaining 14 infants, 13 had no quantifiable CZP levels at birth (<0.032 g/mL), and 1 had a minimal CZP level of 0.042 g/mL (infant/mother plasma ratio 0.0009); no infants had quantifiable CZP levels at weeks 4 and 8. Of 16 umbilical cord samples, 1 was excluded due to missing data; 3/15 had quantifiable CZP levels (maximum 0.048 g/mL). Conclusions There was no to minimal placental transfer of CZP from mothers to infants, suggesting lack of in utero foetal exposure during the third trimester. These results support continuation of CZP treatment during pregnancy, when considered necessary. Trial registration number NCT02019602; Results.