Second-line tenofovir alafenamide for children with HIV in Africa

Abstract

Background Children living with HIV have few second-line antiretroviral therapy(ART) options, especially fixed-dose-combinations(FDC). Methods Children from Uganda, Zambia, Zimbabwe were randomised to second-line tenofovir alafenamide(TAF)/emtricitabine(FTC) or standard-of-care(SOC) backbone (abacavir(ABC) or zidovudine(ZDV) with lamivudine(3TC)) in the factorial CHAPAS-4 trial(ISRCTN22964075). The second randomisation (reported elsewhere) was to dolutegravir(DTG), ritonavir-boosted darunavir(DRV/r), atazanavir(ATV/r) or lopinavir(LPV/r) as anchor drug. All drugs were dosed using WHO weight-bands and children <25kg received a new paediatric TAF/FTC(15/120mg) FDC tablet. The primary endpoint was viral load(VL)<400copies/ml at week-96, analysed using logistic regression, hypothesising that TAF/FTC would be non-inferior to SOC (10% margin). Secondary endpoints included safety and immunological outcomes. Analyses were intention-to-treat. Results 919 children 3-15years, 497(54%) male, median[IQR] baseline viral load(VL) 17,573copies/ml [5549-55,700] and CD4 count 669cells/mm3[413-971], spent 99% of time on allocated NRTI backbone. At week-96, 406/454(89.4%) receiving TAF/FTC vs. 378/454(83.3%) receiving SOC had VL<400copies/mL (adjusted difference[95%CI]: 6.3%[2.0%,10.6%], p=0.004), with no evidence that this varied by ABC/3TC or ZDV/3TC SOC. CD4 count improved similarly in both arms. Growth was better with TAF/FTC vs. SOC, without evidence of excess weight-gain with any backbone/anchor drug combination (including DTG +/- TAF/FTC, interaction p=0.51). Bone health parameters were similar between arms, irrespective of anchor drug. One child died (treatment-unrelated); 29(3%) had serious adverse events without differences between arms. Conclusions TAF/FTC was virologically superior to SOC ZDV/3TC or ABC/3TC with a favourable safety profile, irrespective of anchor drug. Development of child-friendly TAF/FTC FDCs (+/- anchor drug) would increase cost-effective ART options for children and reduce drug access gaps between children and adults.