Safety and efficacy of fosamprenavir in human immunodeficiency virus-infected pregnant women.

To the Editors: In the United States, highly active antiretroviral therapy (HAART) is recommended during pregnancy to reduce the risk of perinatal transmission of human immunodeficiency virus (HIV) and to improve the health of the mother. Many HAART regimens used during pregnancy include a protease inhibitor. Although the protease inhibitor fosamprenavir has been available since 2003, no prospective data to date have been presented regarding its safety and efficacy when used during pregnancy. COL108577 was a retrospective, observational case series evaluating mother and infant outcomes for all HIV-positive pregnant women, from one clinical practice, who delivered while taking fosamprenavir. Patients’ charts dating from October 2003 to date were reviewed. Given the expected sample size of approximately 10 mother-infant pairs, no statistical testing was planned, and results of abstracted data were intended to be descriptive. Baseline was defined as the last observation before fosamprenavir initiation, whereas the delivery value was the observation at or closest to delivery. Data were available for 9 motherinfant pairs. Median baseline age of the mothers was 33 years (range, 20 – 43). Six women were naive to HAART at baseline. In addition to fosamprenavir, HAART regimens included boosting with ritonavir (n 7) and initial nucleoside reverse transcription inhibitor backbones of zidovudine/lamivudine (n 6), tenofovir/emtricitabine (n 1), didanosine/ emtricitabine (n 1), and abacavir/lamivudine (n 1). During the observation period, 1 woman switched her zidovudine/lamivudine backbone to tenofovir/ emtricitabine. Improvements were observed both in viral load and in CD4 T-cell count consistently across the study cohort (Table 1). Compared with baseline, delivery viral loads decreased for each of the 8 women who had started with a detectable level; and for the 1 woman with an undetectable viral load ( 50 copies/mL) at baseline, her viral load remained undetectable at delivery. Additionally, CD4 T-cell counts increased for all 9 women. No hepatic, renal, or pancreatic abnormalities were seen in the mothers. The regimens were well-tolerated. Delivery modes were as follows: 4 vaginal, 4 scheduled c-section, and 1 emergent c-section. Median gestational age was 37 6/7 weeks (range, 35 4/7–42). For infants outcomes, the median of the 3 APGAR score readings was 8.67 (range, 7.33–9.00). Median birth weight and height were 3041 g (range, 2175–4216) and 51 cm (range, 43.8 –58.4), respectively. CNS abnormalities, sometimes of concern with sulfonamide-containing products, were not observed in the infants, nor were any adverse events attributed to fosamprenavir. To date, all infants (n 9) have tested negative for HIV by polymerase chain reaction. In conclusion, this small study showed that fosamprenavir-based HAART was well-tolerated in a cohort of pregnant women, with most of the women achieving favorable immunologic and virologic responses comparable to those reported with other protease inhibitor-based regimens administered during pregnancy. In infants, good birth outcomes and no significant adverse events were reported, and no mother-to-child transmission of HIV was detected. Claudia Martorell, MD, MPH, FACP The Research Institute ctmartorell@idresearchinstitute.com