We propose to develop a near patient assays to score 2 SNPs associated with abacavir-severe cutaneous adverse reactions (SCAR);i.e., HLA B*5701 and the Hsp70-Hom M493T allele (a.k.a. rs2227956CT). Nucleic acid templates will be isolated from cells obtained from cheek swabs with the Trimgen's BuccalQuick"""""""" (Sparks, MD). Two genotyping assays will be developed using our proprietary helicase dependent amplification (HDA). HDA products will be detected with a lateral flow device encased in an amplicon containment vessel that prevents contamination of the laboratory. In Phase I we will Implement design control, and secure ISO 13485 certification for BioHelix. We will also develop typing assays for the aforementioned SNP loci using this technology platform. Finally we will collaborate with PGXL to validate the performance of these assays relative to a gold standard (DNA sequencing) using a set of 50 clinical specimens collected by PGXL researchers. In Phase II, we would perform a prospective, multi-site clinical study aimed at validating the assays as a means of predicting the risk of SJS and TEN in patients being prescribed abacavir for the treatment of AIDS.
Abacavir (ABC), a human immunodeficiency virus-1 (HIV-1) nucleoside- analogue reverse transcriptase inhibitor, is coformulated with lamivudine (3TC ) and zidovudine (ZDV) in Trizivir;a single one a day pill with no food restrictions, limited drug-drug interactions, and a favorable resistance profile. Trizivir in combination with other HIV drugs, is recommended by the US Department of Health and Human Services Consensus Panel Guidelines as a possible initial treatment in antiretroviral-naive patients. ABV is also used in a combo with lamivudine in Epzicom(R). In addition, ABC (sold as a single drug under the name Ziagen(R)) is part of the first-line regimens used in developing countries because of its low cost (www.who.int/hiv/pub/guidelines/adult/en/index.html). Two single nucleotide polymorphisms (SNP) are highly association with abacavir-severe cutaneous adverse reactions (SCAR). HLA B*5701 is a known genetic risk factor for ABC hypersensitivity in Caucasians (Martin et al. 2005). The Hsp70-Hom M493T allele (a.k.a. rs2227956CT) in combination with HLA-B*5701 is strongly associated with ABC hypersensitivity. Although assays exist for HLA typing, these are costly, and yield more information that the strict necessary for detecting the risk of ABC hypersensitivity. For example, targeted DNA sequencing is used for high resolution typing, and sequence-specific primer (SSP), or sequence specific oligonucleotide probe (SSOP) based assays are used for low resolution HLA typing. SSP and SOPP assays typically 20 to 100 different primer sets or probes are used for each locus. DNA sequencing remains a complex and costly method for DNA diagnostics. The method we propose to develop would be lower cost and easy to implement in near patient settings.
