This is a randomized, open-label, phase II, single-centre study, with one LXE408 regimen and one calibrator arm with the standard of care SSG combined with PM, to be conducted in male and female adult (≥18 years and <45 years) patients with confirmed primary visceral leishmaniasis in Ethiopia.

The study will enrol and randomize approximately 52 patients aged ≥18 years and <45 years in a ratio of 3:1 (arm 1 to arm 2):

• Arm 1: LXE408 orally once daily for 14 days (39 patients)
• Arm 2: Standard of care sodium stibogluconate 20 mg/kg/day intravenous/intramuscular (IV/IM) q.d. and paromomycin 15 mg/kg/day IM q.d. for 17 days (13 patients)

In both arms, the study will consist of a screening period of up to 7 days, a treatment duration of 14 or 17 days, and a follow-up period from end of treatment to Day 180. All patients will be hospitalized for approximately 21-24 days, from the first day of the screening period to the Day 14 or Day 17 visit (LXE408 or SSG/PM arms, respectively), after which they are expected to be discharged. They will return to the study sites at the scheduled Day 28 visit (±1 day) for the initial test of cure (primary endpoint), at Day 56 visit (± 7 days) and for the EOS visit at Day 180 (± 14 days) for the final assessment of cure (secondary endpoint). In addition, during follow-up between Day 56 and Day 180, the study team will contact the study patients by phone on a monthly basis to check on their well-being and any reappearance of VL symptoms.

This study is run by DNDi with Novartis as co-development partner.

Inclusion Criteria:

• Male and female patients ≥18 and <45 years (at the time of the screening visit) who are able to comply with the study protocol
• Written informed consent must be obtained before any study protocol specific assessment is performed, other than procedures performed as part of standard of care
• Primary symptomatic VL (defined as typical parameters including, but not limited to, fever for >2 weeks, weight loss and splenomegaly)
• Visualization of Leishmania amastigotes by microscopy in tissue samples (spleen or bone marrow)

Exclusion Criteria:

• Clinical signs of severe VL (including for example jaundice, spontaneous bleeding, oedema, ascites, coma, organ failure)

• Laboratory abnormalities including ALT/SGPT >3 times ULN, total bilirubin >1.5 times ULN, creatinine >1.5 times ULN, serum amylase or lipase >1.5 times ULN, haemoglobin <6 g/dL or other clinically significant abnormal laboratory parameters which, in the opinion of the investigator, may indicate severe VL

• Patients with history of visceral leishmaniasis and confirmed relapse

• Patients with para-kala-azar dermal leishmaniasis

• Patients with severe malnutrition (Mid-Upper Arm Circumference (MUAC) <170 mm)

• History of congenital or acquired immunodeficiency, including positive HIV (test at screening), as these patients present lower efficacy rates, higher toxicity and higher lethality compared to non-HIV patients, requiring different case management and care

• ECG abnormalities, either historic (no longer present) or current which, in the view of the investigator, indicate a significant risk to study participation. These include, but are not limited to, the following:

  1. Clinically significant cardiac arrhythmias (e.g., sustained ventricular tachycardia and clinically significant second- or third-degree AV block without a pacemaker)
  2. QTcF ≥ 450 ms
  3. History of familial long QT syndrome or known family history of Torsades de Pointes
  4. Resting heart rate (physical exam or 12 lead ECG) <60 bpm

• Concomitant known infections, including tuberculosis, severe malaria and any other serious underlying disease that may interfere with disease assessment (e.g., cardiac, renal, hepatic, haematologic and pancreatic)

• Infection with hepatitis B (HBV) or hepatitis C virus (HCV). Patients with a positive HBV surface antigen (HBsAg) test, or if standard local practice, a positive HBV core antigen test, and patients with a positive HCV antibody test must be excluded and will be followed up as per local practice.

• Known history of hearing impairment and/or clinical signs and symptoms of hearing impairment identified during routine physical examination

• Patients with previous history of hypersensitivity reaction or known drug class allergy to any of the study treatments or excipients

• Pregnant or nursing (lactating) women

• Women of childbearing potential who do not agree to have a pregnancy test done at screening and who do not agree to use highly effective contraception while taking the investigational drug and for 5 days after stopping the investigational drug

• Sexually active males unwilling to use a condom during intercourse while taking the investigational drug and for 5 days after stopping the investigational drug

• Patients who cannot comply with the planned scheduled visits and procedures of the study protocol