Hydroxypropyl-beta-cyclodextrin (HPbCD)
In April 2009, hydroxypropyl-beta-cyclodextrin (HPbCD) was approved under compassionate use by the U.S. Food and Drug Administration (FDA) to treat Addison and Cassidy Hempel, identical twin girls who had Niemann–Pick type C disease. Medi-ports, similar to ports used to administer chemotherapy drugs, were surgically placed into the twins chest walls and allow doctors to directly infuse HPbCD into their bloodstreams. Treatment with cyclodextrin has been shown to delay clinical disease onset, reduced intraneuronal storage and secondary markers of neurodegeneration, and significantly increased lifespan in both the Niemann–Pick type C mice and feline models. This is the second time in the United States that cyclodextrin alone has been administered in an attempt treat a fatal pediatric disease. In 1987, HPbCD was used in a medical case involving a boy with severe hypervitaminosis A.On May 17, 2010, the FDA granted Hydroxypropyl-beta-cyclodextrin orphan drug status and designated HPbCD cyclodextrin as a potential treatment for Niemann–Pick type C disease. On July 14, 2010, Dr. Caroline Hastings of UCSF Benioff Childrens Hospital Oakland filed additional applications with the FDA requesting approval to deliver HPbCD directly into the central nervous systems of the twins in an attempt to help HPbCD cross the blood–brain barrier.
In the study, nutritional supplementation contained 250kcal, consisting of 6g of lipids, 40g of carbohydrates, 9g of protein, vitamins and minerals, consumed three times per day. Nutritional intervention also significantly prolonged the time between the diagnosis of TTTS and delivery (9.4 ± 3.7 weeks versus 4.6 ± 6.5 weeks; P = 0.014). The earlier nutritional regimen was introduced, the lesser chance of detecting TTTS ( P = 0.001). Although not statistically significant, dietary intervention was also associated with lower Quintero stage, fewer invasive treatments, and lower twin birth weight discordance.Diet supplementation appears to counter maternal metabolic abnormalities in monochorionic twin pregnancies and improve perinatal outcomes in TTTS when combined with the standard therapeutic options. Nutritional therapy appears to be most effective in mitigating cases that are caught in Quintero Stage I, little effect has been observed in those that are beyond Stage I. Epidemiology
Based on recent (2005) US NCHS data, the rate of multiple births is now approximately 3.4% (4,138,349 total births, of which 139,816 were twins or higher-order multiple births). The majority of identical twins share a common (monochorionic) placenta, and of these approximately 15% go on to develop TTTS.