A Trial to Assess Safety and Efficacy of Topical MBN-101 in Patients With Moderate/ Severe DFI

This is a randomized, double-blind, placebo-controlled, multi-center study that will be
conducted in two parts. In Part I, patients will be enrolled into escalating dose cohorts
(150, 375, or 600 µg/mL) (N=16/cohort) at a ratio of 3:1 (Active to Placebo). In Part II,
patients will be randomized in a 1:1 ratio (Active to Placebo) based on the optimal dose
demonstrated in Part I.

Patients with diabetes mellitus and a foot infection with an Infectious Disease Society of
America (IDSA) infection severity rating of moderate or severe will be eligible for the
trial. Both inpatients and outpatients are eligible if they meet all inclusion/exclusion
criteria, however all enrolled patients must remain in-hospital for the first 24 hours after
initial dosing. Patients with a need for surgical therapy (e.g., incision and drainage or
removal of necrotic tissue) beyond standard bedside wound debridement should not be enrolled.

Patients will be randomized to receive either topical application of MBN-101 or topical
application of vehicle, applied directly to the target site, 3 times per week, for a minimum
of 14 days and up to a maximum of 21 days. The determination to stop topical antibiotic
therapy will be at the discretion of the principal investigator, and should be based on the
resolution of findings of infection. All patients will also receive systemic antibiotic
treatment based on the protocol defined algorithm. Systemic antibiotic therapy should
continue until, but not beyond, the resolution of findings of infection, as outlined in the
2012 IDSA clinical practice guideline for the diagnosis and treatment of diabetic foot
infections,

Inclusion Criteria:

- Has diabetes mellitus, according to the American Diabetes Association (ADA) criteria

- Has a foot infection as defined by the IDSA guidelines, with a severity rating of
moderate or severe

- Either no current or recent (within 72 hours) antibiotic therapy for the DFI,

- Has documented adequate arterial perfusion in the affected limb (either palpable
dorsalis pedis or posterior tibial pulses, or normal Doppler wave forms, or a toe
blood pressure ≥ 45 mm Hg, or an ankle-brachial index (ABI) of >0.6)

Exclusion Criteria:

- Proven or highly suspected, involvement of bone (i.e., osteomyelitis)

- More than one concurrent, infected, diabetic foot ulcer

- Hemoglobin A1c > 11 on the day of presentation

- Requirement for ongoing immunosuppressive therapy (topical or inhaled corticosteroids
are permitted)

- Serum creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) or
Alkaline Phosphatase >2 times the upper limit of the normal range of the local testing
laboratory

- Absolute neutrophil count <1000

- Any condition that has required treatment with any other bismuth containing compound
within the last 2 weeks (i.e., Kaopectate or Pepto-Bismol)

- Participation in an investigational trial to evaluate pharmaceuticals or biologics
within the past 3 months

- Need for any surgical therapy beyond debridement to treat the diabetic foot ulcer
(e.g., incision and drainage, removal of necrotic tissue)

- Planned lower extremity amputation that will include their infected ulcer

- Known allergy to bismuth and/or MBN-101 excipients (methylcellulose, Tween 80
(polysorbate 80))

- Female patients who are pregnant, lactating, or who have a positive serum human
chorionic gonadotropin (pregnancy) as determined by laboratory testing

- Immunocompromised due to illness or organ transplant

- History of any type of cancer (excluding non-melanoma localized skin cancer or
completely excised and cured carcinoma-in-situ of uterine cervix)

- History of major medical noncompliance

- Other medical conditions which, in the opinion of the Principal Investigator, would
jeopardize the safety of the study subject or impact the validity of the study results