Human immunodeficiency virus type 1 protease genotype predicts immune and viral responses to combination therapy with protease inhibitors (PIs) in PI-naive patients.

Protease genotype, as a variable in outcome to combination therapy for human immunodeficiency virus (HIV) type 1 infection, was evaluated among protease inhibitor-naive children and adolescents who had received extensive treatment with reverse-transcriptase inhibitors. After 24 weeks of combination therapy, 35% had viral and immune success (VSIS patients), 19% had viral and immune failure (VFIF patients), and 46% had viral failure but marked improvement in CD4 T cells (VFIS patients). Disease stage was the only pretherapy clinical variable associated with outcome (P=.02). Although reverse-transcriptase genotype was unrelated to outcome, pretherapy protease genotype was related significantly to therapy response (P=.005). Odds for immune or viral failure were 17.7 to 1 and 2.5 to 1, respectively, for protease genotype as a single variable. Protease genotype combined with disease stage and CD4 cell percentage predicted correct therapy response for 81% of patients (100% of VFIF, 78% of VSIS, and 75% of VFIS patiens). Naturally occurring amino acid polymorphisms in protease provide sensitive biomarkers for treatment response among inhibitor-naive patients with advanced HIV disease.