Interim analysis of peginterferon beta-1a in the breast milk of lactating patients with multiple sclerosis (2790)

Objective: Evaluate the concentration of peginterferon beta-1a in the breast milk of lactating multiple sclerosis (MS) patients receiving subcutaneous peginterferon beta-1a treatment. Background: Data on the transfer of MS disease-modifying therapies into breast milk are limited. In a previous study of intramuscular interferon beta-1a (IM IFN), the highest observed breast milk concentration was 179 pg/mL, with an estimated relative infant dose of 0.006%. However, the extent to which peginterferon beta-1a, a larger pegylated molecule, is excreted into human breastmilk is not known. Design/Methods: This interim analysis includes data from 6 women with MS who initiated peginterferon beta-1a treatment during lactation. Patients collected a baseline breast milk sample prior to treatment initiation. Following a single injection of peginterferon beta-1a 125 mcg, daily breast milk samples ≥10 mL were collected on days 1–14. Patients did not up-titrate peginterferon beta-1a. Mean breast milk concentrations, geometric mean maximum concentration (Cmax), median time to Cmax (Tmax), and median time to last measurable concentration (Tlast) were assessed. Samples below the detection threshold (15.0 pg/mL) were treated as missing values. Results: The peginterferon beta-1a concentration in breast milk at baseline was below detectable levels. After peginterferon beta-1a dosing, the maximum breast milk concentration recorded was 126.2 pg/mL. The geometric mean Cmax was 48.9 pg/mL; median Tmax and Tlast were 4 and 7 days, respectively. Mean breast milk concentrations were 56.0, 56.9, 42.8, and 27.4 pg/mL on days 1, 5, 10 and 14. Conclusions: In this analysis, the maximum peginterferon beta-1a concentration in breast milk was 126.2 pg/mL. These findings may be useful for clinicians considering postpartum treatment options for patients with MS. Disclosure: Dr. Houtchens has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen, Serono, Alexion, Sanofi Genzyme, Roche, and Teva. Dr. Houtchens has received research support from Serono, Biogen, and Sanofi Genzyme.Dr. Manieri has nothing to disclose. Dr. Mahlanza has nothing to disclose. Dr. Ciplea has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Travel grants from Sanofi Genzyme, Teva and Novartis. Dr. Ramia has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employee of and own stock and/or stock options in Biogen. Dr. Zhao has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employee of and own stock and/or stock options in Biogen. Dr. England has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen and US Medical. Dr. Avila has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen. Dr. Hellwig has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Bayer, Biogen, Sanofi, Teva, Roche, Novartis, and Merck. Dr. Hellwig has received research support from Bayer, Biogen, Merck, Novartis, Sanofi, Genzyme, and Teva.