Efficacy of INM004 in Children With STEC-HUS

Inclusion Criteria:

1. Age ≥ 9 months and < 18 years at the time of randomization.

2. In addition, only for subjects < 1 year and ≥ 15 years, confirmation of STECinfection determined by:

3. Detection of generic Stx, Stx1, Stx2, or Stx1/Stx2 in stools by enzymeimmunoassay (EIA); or

4. Detection of stx, stx1, stx2, or stx1/stx2 genes in stools by Polymerase ChainReaction (PCR); or

5. Detection of specific anti-polysaccharide (IgM) antibodies in serum; or

6. Fecal culture positive for E. coli O157 confirmed by serogroup-specificseroagglutination.

7. Hospitalization at the participating institution.

8. History of onset of diarrhea within 10 days prior to STEC-HUS diagnosis at theparticipating institution.

9. Diagnosis of STEC-HUS defined as a subject with signs of renal damage, hemolysis,and platelet consumption:

10. Signs of renal damage defined as:

• Serum creatinine value above the ULN for age and sex, and GFR below theLLN for age, sex, and height.

2. Presence of hemolysis documented by:

• LDH levels above the ULN for age, and/or
• Presence of schistocytes in peripheral blood smear.

3. Platelet consumption according to any of the following laboratory criteria:

• Peripheral blood platelet count < 150 × 103/μL, and/or
• A ≥50% decrease in peripheral blood platelet count compared to a samplecollected within the previous 24 hours.

6. Informed consent form signed and dated by the subject or, the legal guardian(s),with the subject's assent as appropriate based on age and regulatory guidelines inthe region.

7. Subjects who have already had menarche must have a negative pregnancy test.

Exclusion Criteria:

1. Start of dialysis within 48 hours prior to admission to the participatinginstitution.

2. More than 24 hours from diagnosis of STEC-HUS at the participating institution up torandomization.

3. History of chronic/recurrent hemolytic anemia, thrombocytopenia, or CKD.

4. Personal and/or family history of atypical HUS.

5. Suspected HUS secondary to infectious processes other than gastrointestinal (e.g.,Streptococcus pneumoniae, HIV).

6. Suspected HUS secondary to other etiologies (e.g., drug-associated HUS, neoplasms,bone marrow or solid organ transplantation, autoimmune disorders).

7. Any other acute or chronic medical condition that, in the opinion of theinvestigator, may interfere with the evaluation of the efficacy and/or safety of thestudy medication.

8. History of: a) anaphylaxis of any kind; b) prior administration of equine serum (e.g., antivenom, anti-arachnid serum, anti-SARS-CoV-2 serum, etc.) or an allergicreaction from contact or exposure to horses.

9. Pregnant or breastfeeding woman.

10. Impossibility of hospitalization in the participating institution.

11. Concurrent participation in another clinical trial or having participated in aclinical trial in the last 3 months.

12. Severe malnutrition. Defined when the weight is three standard deviations below themedian, according to height, age and sex as per WHO guidelines.

13. Medical conditions that may affect kidney function or cause/enhance neurologicalsymptoms or signs:

• Congenital or acquired anomalies that may affect functioning renal mass.

• Epilepsy or structural abnormalities of the brain that may increase the risk ofseizures.

• Trisomy 21.

• Prematurity (born before 28 weeks gestation).

• Other (according to investigator criteria).