What the Orphan Drug Act has done lately for children with rare diseases: a 10-year analysis.

OBJECTIVES: The 1983 US Orphan Drug Act (ODA) provided incentives to stimulate treatment product development for patients with rare disease. This article highlights a decade of ODA contributions to this goal for children with RDs. METHODS: An internal US Food and Drug Administration database was the information source for orphan designations, marketing approvals, and prevalence numbers for 2000 to 2009. Product categorization was based on the disease age of onset for which they received designation. Category 1 products were for diseases with onset exclusively in Childhood; Category 2 products were for diseases with onset at any age; and Category 3 products were for diseases with adult onset only. Disease prevalence distributions were analyzed by using population intervals of 20 000. RESULTS: From 2000 to 2009, 1138 orphan drugs were designated and 148 received marketing approval, of which 38 (26%) were for pediatric diseases. The proportion of approvals for pediatric products increased from 17.5% (10 of 57) in the first half of the decade, to 30.8% (28 of 91) in the second. More products received designation and marketing approval for pediatric diseases with prevalence numbers fewer than 20 000 than for any other prevalence subgroup. The median disease prevalence for all pediatric orphan designations that received marketing approval was 8972. Among the pediatric orphan drug approvals categorized by therapeutic class, the endocrine/metabolic drugs had the largest representation (39%). CONCLUSIONS: The ODA incentives have led to increased product availability for RDs overall, with an increasing number of marketing approvals for children this past decade.

The Orphan Drug Act and the development of stem cell-based products for rare diseases.

The Orphan Drug Act encourages the development of products for rare diseases and conditions. Many conditions that stand to benefit from stem cell-based products are rare diseases. We address the Orphan Drug Act in relation to the development of stem cell-based products.

RhoBTB2 (DBC2) is a mitotic E2F1 target gene with a novel role in apoptosis.

We have identified the RhoBTB2 putative tumor suppressor gene as a direct target of the E2F1 transcription factor. Overexpression of E2F1 led to up-regulation of RhoBTB2 at the level of mRNA and protein. This also occurred during the induction of E2F1 activity in the presence of cycloheximide, thus indicating that RhoBTB2 is a direct target. RNAi-mediated knockdown of E2F1 resulted in decreased RhoBTB2 protein expression, demonstrating that RhoBTB2 is a physiological target of E2F1. Because E2F1 primarily serves to transcribe genes involved in cell cycle progression and apoptosis, we explored whether RhoBTB2 played roles in either of these processes. We found RhoBTB2 expression highly up-regulated during mitosis, which was partially dependent on the presence of E2F1. Furthermore, overexpression of RhoBTB2 induced a short term increase in cell cycle progression and proliferation, while long term expression had a negative effect on these processes. We similarly found RhoBTB2 up-regulated during drug-induced apoptosis, with this being primarily dependent on E2F1. Finally, we observed that knockdown of RhoBTB2 levels via siRNA delayed the onset of drug-induced apoptosis. Collectively, we describe RhoBTB2 as a novel direct target of E2F1 with roles in cell cycle and apoptosis.

E2F4 deficiency promotes drug-induced apoptosis.

E2F1 and E2F4 are known to have opposing roles in cell cycle control. In the present work, we examine the role of both E2F1 and E2F4 in apoptosis induced by three cyclin-dependent kinase inhibitors (roscovitine, BMS-387032, and flavopiridol) as well as by three established chemotherapeutic drugs (VP16, cisplatin and paclitaxel). We find that E2F4 levels are diminished following treatment with cyclin dependent kinase inhibitors (flavopiridol, roscovitine and BMS-387032) or with DNA damaging drugs (cisplatin and VP16). In contrast, each of these drugs induced E2F1. We find that mouse fibroblasts nullizygous for the E2F4 gene are more sensitive to apoptosis induced by roscovitine, flavopiridol, cisplatin, and VP16, whereas E2F1-deficient fibroblasts are less sensitive. Likewise, we find that RNAi-mediated reductions in E2F4 in human cancer cells results in increased drug sensitivity. Taken together, these results support a model in which E2F1 and E2F4 play opposing roles during drug-induced apoptosis.