ICIs in pregnancy no worse than other treatments, with one exception

2 minute read

Despite advice to opt for alternative treatments during pregnancy, new research suggests risk is similar to other anti-cancer therapies.

Pregnant patients taking immune checkpoint inhibitors (ICIs) are not at greater risk of adverse fetal outcomes than with other cancer therapies, a study published in JAMA Network Open has found.

ICIs are often discouraged as a treatment option during pregnancy due to the lack of available safety data and the difficulty in balancing maternal and neonatal health, the authors said. But their results showed that ICI exposure was not associated with overreporting of adverse maternal, fetal or newborn events compared with other anti-cancer therapies.

More than 3500 cases of maternal exposure to anticancer drugs from the World Health Organization’s global pharmacovigilance database (up to June 2022) were assessed. ICIs such as anti-PD1, anti-CTLA4, anti-PD1 with anti-CTLA4, anti-PD-L1, and anti-PD1 with anti-lymphocyte activation gene 3 made up nearly 3% of the total cases.

Most of the participants were undergoing treatment in the US, and the most common conditions being treated by non-ICI drugs were breast cancer and chronic myeloid leukemia. The ICI treatment group was mostly made up of those diagnosed with melanoma or lymphoma.

There was no greater association with adverse maternal, fetal or newborn events in the group of people treated with ICIs compared with other anti-cancer therapies.

However, the researchers advised caution when using the combination anti-PD1 and anti-CTLA4 therapy. There was a significant overreporting of preterm birth in this treatment group as compared to other anti-cancer treatments (80% vs 23%) that was not reflected in other ICI treatments.

Some rare immune-related neonatal adverse events were noted in those undergoing this treatment that was not seen in other ICIs. There was one case of transient congenital hypothyroidism, one case of maternal antiphospholipid syndrome which led to spontaneous abortion, and one case of pneumonitis leading to neonatal respiratory distress syndrome and death.

The report said that roughly 0.1% of all pregnancies occur during active cancer treatment and it’s considered rare. However, there is still a need for comprehensive safety data and toxicity information.

“The intentional or unintentional use of ICIs for cancer in pregnant individuals is expected to rise,” the authors noted.

“With the recent approval of anti-PD1 drugs for breast cancers, an increase in the exposure of pregnant individuals to ICIs is anticipated.”

JAMA Network Open, online April 17

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