Abstract

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High sensitivity of HLA-B*5701 in Whites and Blacks in immunologically-confirmed cases of abacavir hypersensitivity (ABC HSR)

Presented by Elizabeth Phillips, Australia.

Saag M.¹, Balu R.², Brachman P.³, Brothers C.², Stancil B.², Mosteller M.², Wannamaker P.², Sutherland-Phillips D.², Phillips E.⁴, Mallal S.⁴, Shaefer M.²

¹University of Alabama, Center for AIDS Research, Birmingham, AL, United States, ²GlaxoSmithKline, Infectious Disease Medicine Development Center, Research Triangle Park, NC, United States, ³Emory University, Atlanta, GA, United States, ⁴Royal Perth Hospital and Murdoch University, Perth, Australia

Objectives: HLA-B*5701 is highly associated with ABC HSR in Whites. However, variable sensitivities are reported across studies and races where clinical data alone defined ABC HSR. Because accurate identification of phenotype is critical for determining sensitivity, this study estimates the sensitivity of HLA-B*5701 in Whites and Blacks using skin patch testing (SPT) to supplement HSR diagnosis.
Methods: Subjects who had clinically-suspected ABC HSR were retrospectively identified and then tested for HLA-B*5701 and underwent ABC SPT (Study ABC107442, clinicaltrials.gov identifier: NCT00373945). Cases were defined as (1) All ABC HSR regardless of SPT results and (2) ABC HSR with a positive SPT result. Controls were subjects who tolerated ABC for ³12 weeks without HSR.
Results:

	White SPT+ HSR	White All HSR¹	White controls	Black SPT+ HSR	Black All HSR²	Black controls
HLA-B*5701 results available, N	42	127	202	5	48	206
HLA-B*5701+, n	42	56	8	5	10	2
HLA-B*5701-, n	0	71	194	0	38	204
Sensitivity (95% CI)	1.0 (0.92, 1.0)	0.44 (0.35, 0.53)	-	1.0 (0.48, 1.0)	0.21 (0.10, 0.35)	-
Specificity (95% CI)	-	-	0.96 (0.92, 0.98)	-	-	0.99 (0.97, 1.00)

¹Includes SPT+ and SPT- cases (3 had no SPT result). Among 82 SPT- cases, 14 were HLA-B*5701+. ²Includes SPT+ and SPT- cases. Among 43 SPT- cases, 5 were HLA-B*5701+.
Conclusions: In these preliminary results, the sensitivity of HLA-B*5701 for SPT+ HSR is 100% in both Whites and Blacks. The sensitivity of HLA-B*5701 was reduced when HSR was defined by clinical diagnosis alone. These data suggest that prospective HLA-B*5701 screening may reduce ABC HSR rates in Whites and Blacks. Not all HLA-B*5701+ cases were SPT+. HLA-B*5701 screening may augment clinical management of HSR but must never substitute for clinical vigilance. To complement these results, a large prospective study (PREDICT-1) evaluating the clinical utility of HLA-B*5701 screening on ABC HSR has been completed.

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