Should a mother hold off on breastfeeding if her baby is on Jakafi (ruxolitinib) for Hemophagocytic Lymphohistiocytosis (HLH)?

Breastfeeding Should Be Avoided While Baby is on Jakafi (Ruxolitinib) for HLH

Mothers should not breastfeed if their baby is receiving Jakafi (ruxolitinib) for Hemophagocytic Lymphohistiocytosis (HLH).

Rationale for Recommendation

Drug Excretion in Breast Milk

• According to the FDA drug label for ruxolitinib, the drug is present in animal milk and likely to be present in human milk 1
• When ruxolitinib was administered to lactating rats, the AUC for total radioactivity in milk was approximately 13 times the maternal plasma AUC, with ruxolitinib and several metabolites present in milk at levels higher than those in maternal plasma 1
• This indicates significant transfer of the medication into breast milk, which could expose the infant to potentially harmful levels of the drug

Safety Concerns

• The FDA label specifically advises women not to breastfeed during treatment with ruxolitinib and for approximately four weeks after the last dose (approximately 5-6 elimination half-lives) due to serious adverse findings including risks of:
  • Serious infections
  • Thrombocytopenia
  • Anemia
  • Neutropenia 1

Specific Guidance for HLH

• While there are limited studies specifically addressing breastfeeding with ruxolitinib in HLH patients, the general principle of avoiding breastfeeding during maternal JAK inhibitor therapy applies
• A pilot study of ruxolitinib as front-line therapy for children with secondary HLH demonstrated efficacy but also highlighted the potent immunomodulatory effects of this medication 2

Considerations for Infant Health

Double Exposure Risk

• If a baby is already receiving ruxolitinib for HLH treatment, additional exposure through breast milk could potentially:
  1. Lead to unpredictable drug levels in the infant
  2. Complicate dosing and monitoring of the infant's prescribed treatment
  3. Increase risk of adverse effects

Alternative Feeding Options

• Formula feeding is recommended while the infant is on ruxolitinib therapy
• If the mother wishes to maintain milk supply, she can pump and discard her milk until breastfeeding is safe to resume

Related Evidence from Other JAK Inhibitors

While limited data exists specifically for ruxolitinib and breastfeeding, evidence from related medications provides context:

• For tofacitinib (another JAK inhibitor), there is a single case report suggesting that prolonged exposure during pregnancy and breastfeeding did not adversely affect infant immune development 3, but this is insufficient evidence to override safety concerns
• Guidelines for tyrosinemia treatment strongly recommend against breastfeeding while the mother is being treated with NTBC (another metabolic medication), highlighting the general caution with medication exposure during breastfeeding 4

Monitoring Recommendations

If breastfeeding has occurred while the infant is on ruxolitinib:

• Monitor for signs of increased drug effects or toxicity
• Consider laboratory monitoring including complete blood count to assess for cytopenias
• Watch for signs of infection due to potential immunosuppressive effects

Conclusion

The available evidence strongly supports avoiding breastfeeding when an infant is receiving ruxolitinib for HLH. This recommendation is based on the FDA drug label warning against breastfeeding during maternal ruxolitinib treatment due to documented excretion into milk and potential serious adverse effects. The risk of additional drug exposure through breast milk outweighs the benefits of breastfeeding in this specific clinical scenario.