Chronic myeloid leukemia diagnosed in pregnancy: management and outcome of 87 patients reported to the European LeukemiaNet international registry.

The management of chronic myeloid leukemia (CML) diagnosed during pregnancy is a rare and challenging situation. We report the treatment and outcome of 87 cases diagnosed in chronic phase from 2001-2022 derived from the largest international observational registry, supported by the European LeukemiaNet (ELN), of 400 pregnancies in 299 CML women. Normal childbirth occurred in 76% without an increased rate of birth abnormalities or life-threatening events, including in patients untreated or treated with interferon-α and/or imatinib in 2nd-3rd trimester. The low birth weight rate of 12% was comparable to that seen in the normal population. Elective and spontaneous abortions occurred in 21% and 3%, respectively. The complete hematologic response rate before labor was 95% with imatinib and 47% with interferon only. No disease progression during pregnancy was observed, 28% of the patients switched their therapy at varying times after delivery. Treatment options balance the efficacy and safety for mother and infant: interferon-α can commence in the 1st trimester and continued throughout in cases of good disease control and tolerability. Because of limited placental crossing, selected tyrosine kinase inhibitors (imatinib and nilotinib) seem to be safe and effective options in 2nd and 3rd trimester while hydroxycarbamide offers few benefits.

Breastfeeding in Patients with Chronic Myeloid Leukaemia: Case Series with Measurements of Drug Concentrations in Maternal Milk and Literature Review.

Breastfeeding in patients with chronic myeloid leukaemia (CML) during tyrosine kinase inhibitors (TKIs) therapy is not recommended but interruption of TKI treatment may cause the loss of remission. We studied the 3 cases of pregnancy and breastfeeding in women with CML and observed that stopping treatment without major molecular response may end in haematological relapse. The concentrations of nilotinib and imatinib in maternal milk were measured and nilotinib distribution in human breast milk was demonstrated for the first time. The estimated maximal doses of imatinib and nilotinib which an infant may ingest with the maternal milk were less than the therapeutical doses. However, the unknown impact of the low dose chronic exposure to these TKIs in infants imposes the limitations on their use during breastfeeding. Breastfeeding without TKI treatment may be safe with molecular monitoring, but preferably in those patients with CML who have durable deep molecular response.

Placental transfer of tyrosine kinase inhibitors used for chronic myeloid leukemia treatment.

Both favorable pregnancy outcomes and fetal abnormalities have been associated with the use of tyrosine kinase inhibitors (TKIs) during pregnancy. The placental transfer of TKIs in humans is poorly understood. We observed women with chronic myeloid leukemia who used imatinib or nilotinib during the late pregnancy stages. The newborns had no birth abnormalities. We evaluated the drug concentrations in maternal blood, umbilical cord blood, and placental samples collected during labor. We found limited placental transfer of the TKIs. The fetal/maternal concentration ratio ranged from 0.5 to 0.58 for nilotinib and from 0.05 to 0.22 for imatinib. The placental/maternal ratio was higher for imatinib than for nilotinib. Theoretical pharmacokinetic modeling of passive placental crossing was insufficient to predict the in vivo data because the calculated fetal/maternal ratio was close to 1 for both drugs. We propose that active placental transport contributes to fetal protection against TKI exposure during pregnancy.