Moxidectin combination therapies for lymphatic filariasis: an open-label, observer-masked, randomised controlled trial
Background
Lymphatic filariasis caused by Wuchereria bancrofti causes hydroceles and lymphedema in millions of individuals worldwide. Annual mass drug administration of ivermectin plus albendazole (IA) temporarily clears microfilariae from the blood of infected individuals and is used in Africa to reduce W bancrofti transmission. This study aimed to investigate whether moxidectin combination therapies are superior to ivermectin combination therapies for clearance of W bancrofti microfilaremia.
Methods
In this open-label, parallel assignment, masked-observer, randomised, superiority clinical trial in Côte d'Ivoire, we used gender-stratified, block randomisation to sequentially assign adults with bancroftian filariasis (1:1:1:1) to receive annual ivermectin plus albendazole (IA; standard of care) or one of three single-dose regimens: moxidectin plus albendazole (MoxA), ivermectin plus diethylcarbamazine (DEC) plus albendazole (IDA), or moxidectin plus DEC plus albendazole (MoxDA). This trial was conducted at the Filariasis Research Center in Agboville, located at the Centre Hôspitalier Regional, d'Agboville, Côte d'Ivoire. Men and non-pregnant, non-breastfeeding women aged 18–70 years in good general health and with screening microfilaria loads of at least 40 per mL (≥3 microfilariae on 60μL nocturnal thick blood smear) were eligible for enrolment; those found to have at least 40 microfilariae per mL by 1 mL blood filtration at enrolment were eligible for inclusion in the primary, modified intention-to-treat, efficacy analysis. Medicines were administered by an unmasked pharmacist; all other team members were masked to treatment assignment. Primary outcomes were complete microfilaria clearance at 12 months (MoxA vs IA) or 24 months (MoxDA vs IDA) post-treatment. This trial is registered at ClinicalTrials.gov (NCT04410406) and is complete.
Findings
Enrolment occurred from Aug 20, 2020 to July 31, 2021. 190 individuals were predicted to have nocturnal blood microfilariae counts of at least 40 microfilariae per mL, of whom 26 were excluded and 164 were randomly assigned to an intervention (41 to the IA group, 40 to the MoxA group, 41 to the IDA group, and 42 to the MoxDA group). 113 participants met the pre-specified efficacy analysis criteria and completed follow-up. The proportion of participants who were amicrofilaraemic at 12 months was eight of 25 (32% [95% CI 15–54]) among IA recipients versus 18 of 19 (95% [95% CI 74–100]) among MoxA recipients (adjusted risk ratio [RR] 2·79 [95% CI 1·59–4·90]; p=0·0004). The proportion of amicrofilaraemic participants at 24 months was 20 of 22 (91% [95% CI 71–99]) for IDA versus 21 of 23 (91% [72–99]) for MoxDA (adjusted RR 0·98 [95% CI 0·83–1·15]; p=0·78). Most MoxA recipients (14 of 16 [88%; 95% CI 62–98]) remained amicrofilaraemic at 24 months.
Interpretation
In this study, single-dose MoxA was superior to IA for W bancrofti microfilaria clearance at 12 months and provided prolonged microfilaria clearance for most participants. These results suggest that MoxA could be a powerful tool to accelerate the elimination of lymphatic filariasis in Africa.