Certain Immunotherapy Drugs Not Recommended for Pregnant Women With Cancer

The use of immune checkpoint inhibitors (ICIs) to treat cancer during pregnancy should be avoided when possible, according to a study published in JAMA Network Open. Adverse pregnancy, fetal and/or newborn outcomes may occur, such as lung and thyroid inflammation, with a risk of miscarriage, researchers found.

The researchers identified three reports of suspected immune-related pregnancy, fetal and/or newborn complications from the ICI group. Complications in one case included antiphospholipid syndrome (immune system mistakenly attacking normal proteins in the blood), pneumonitis (lung inflammation) and thyroiditis (inflamed thyroid gland), which were associated with a miscarriage within the first 20 weeks of pregnancy, the researchers stated.

Another case from the study reported a patient’s fetus experiencing fetal pneumonitis (lung inflammation in the fetus), which was potentially immune-related and led to neonatal respiratory distress syndrome.

Severe outcomes were reported in three other patients from the ICI group, the researchers noted. One patient experienced intrauterine growth restriction, which led to hand malformation in the fetus. Preterm birth and neonatal respiratory disorder also occurred in this patient, researchers determined.

Researchers from the study emphasized avoiding ICI treatment because of the possible rare immune-related neonatal side effects that may occur. They noted that a discussion with the care team about risk-benefit for the mother and the unborn child should be had, considering the urgency of ICI use.

“We found no overreported outcomes in the group exposed to ICIs compared with the group exposed to other anticancer agents for all maternal, fetal and newborn adverse outcomes explored,” the researchers wrote.

READ MORE: Pausing Endocrine Therapy for Pregnancy May Not Impact Breast Cancer Recurrence Risk

There were 91 patients included in the study who had been exposed to ICIs during pregnancy. The study also included 3,467 patients who had received other anti-cancer drugs. The average age of women in the study was 28.7 years old, according to the researchers.

Common cancer types included 685 reports of breast cancer and 611 reports of chronic myeloid leukemia (CML). Patients in the study were placed into two groups, depending on their treatment. The commonly diagnosed cancers in the group of patients who received other anticancer drugs included breast cancer and CML. In the ICIs group, common cancer types were melanoma and lymphoma.

In the ICI group, approximately 42% of patients reported adverse pregnancy, fetal and/or newborn outcomes, the researchers determined. Approximately 57% of patients in the other anticancer drug group reported adverse pregnancy, fetal and/or newborn outcomes.

“None of the 45 explored maternofetal outcomes were overreported in the ICI-exposed group compared with the group exposed to other anticancer drugs,” researchers wrote.

Of note, researchers determined that preterm birth (premature birth before the 37th week of pregnancy) was overreported significantly in the ICI group (80% versus 23% in the other anticancer drug group). This was found specifically regarding treatment with the anti-PD1 plus anti-CTLA4 ICIs, compared with other anticancer drugs. However, the researchers noted that preterm birth was not overreported in patients who received anti-PD1 or anti-PD-L1, or anti-CTLA4 monotherapy ICI.

“The findings suggest that the use of ICIs during pregnancy seems to be better tolerated than previously suspected. However, due to possible rare immune-related neonatal adverse events, ICI use, especially the anti-PD1 or anti–PD-L1 plus anti-CTLA4 combination, in pregnant women should be avoided when possible,” the researchers concluded.

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