Abstract Details

Title Minimal concentrations of rituximab in the breastmilk of women treated for multiple sclerosis

Topic Multiple Sclerosis

Presentation(s) P4 - Poster Session 4 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-097

Objective To determine the concentration of rituximab in breastmilk of women treated with rituximab for multiple sclerosis (MS).

Background

Women with MS have high risk of postpartum relapses. Currently, due to lack of data, the standard of care is for them to choose between resuming MS therapies or breastfeeding their child. Rituximab, a monoclonal antibody against the B-lymphocyte CD20 surface antigen, is effective in MS and other autoimmune and oncologic conditions affecting women during childbearing years. A single case study reported a low concentration of rituximab in breastmilk, and studies of other monoclonal antibodies in breastmilk suggest minimal-to-no transfer.

Design/Methods In this single-center study, we collected breastmilk samples (n=6) from four lactating women with MS receiving rituximab (500mg IV or 1000mg IV once while breastfeeding) from November 2017 to October 2018. One sample was collected prior to infusion (drug-naïve); the remaining samples were collected at discrete timepoints from infusion start; samples were frozen immediately after collection. To determine the concentration of rituximab, samples were analyzed using an ELISA assay. For each sample, we calculated the average rituximab concentration across three standard curves (dilution buffer, neat naïve milk and 1:10 naïve milk) measured at either a 1:2 or 1:10 dilution.

Results We detected minimal concentrations of rituximab in all exposed breastmilk samples (n=5). For those who received rituximab 500mg IV (n=2), the average breastmilk rituximab concentration was 6.6 ng/mL at 8 hours (n=1), 31.5 ng/mL at 10 hours (n=1), and 380.9 ng/mL at 26 hours (n=1) from infusion initiation. For those who received rituximab 1000mg IV (n=2), the average rituximab concentration was 2.2 ng/mL at 48 hours (n=1) and 1,154.4 ng/mL at 11 days (n=1) from infusion initiation.

Conclusions

In this largest study of rituximab concentration in breast milk to date, we detected minimal transfer of rituximab (<1.2 mg/mL in all cases), with some variability across patients and timepoints. While this study validates the feasibility of assessing the concentration of rituximab in breast milk, it establishes the need for a larger longitudinal study that includes additional timepoints and infant outcome measures.

Authors/Disclosures
Sara LaHue, MD PRESENTER	The institution of Dr. LaHue has received research support from National Institute on Aging . The institution of Dr. LaHue has received research support from Larry L. Hillblom Foundation . The institution of Dr. LaHue has received research support from UCSF Claude D. Pepper Older Americans Independence Center . The institution of Dr. LaHue has received research support from UCSF Bakar Aging Research Institute. The institution of Dr. LaHue has received research support from Doris Duke Foundation . The institution of Dr. LaHue has received research support from National Institute on Aging . The institution of Dr. LaHue has received research support from Longevity Impetus Grants. Dr. LaHue has received publishing royalties from a publication relating to health care.
Kristen M. Krysko, MD (St. Michael's Hospital)	Dr. Krysko has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. Dr. Krysko has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Roche. Dr. Krysko has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for EMD Serono. Dr. Krysko has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. Dr. Krysko has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Krysko has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. The institution of Dr. Krysko has received research support from MS Society of Canda. The institution of Dr. Krysko has received research support from Roche.
Alice Edwards, DO	The institution of Dr. Rutatangwa has received research support from NIH.
Annika Anderson	No disclosure on file
	No disclosure on file
Lynn Do, PharmD (Eli Lilly)	Dr. Do has received personal compensation for serving as an employee of Eli Lilly.
Riley Bove, MD, FAAN (University of California, San Francisco)	Dr. Bove has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Alexion. Dr. Bove has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Amgen. Dr. Bove has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genzyme-Sanofi. Dr. Bove has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for TG Therapeutics. Dr. Bove has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for EMD-Serono. Dr. Bove has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cadenza. The institution of Dr. Bove has received research support from Biogen. The institution of Dr. Bove has received research support from Eli Lilly. The institution of Dr. Bove has received research support from Novartis. The institution of Dr. Bove has received research support from Roche Genentech.

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