A Phase 3 Clinical Trial of Intravenous Sodium Thiosulfate in Acute Calciphylaxis Patients

Inclusion Criteria:

• Informed of the investigational nature of the study and sign written informed consent

• Willing and able to adhere to all study-related procedures, including adherence tostudy medication regimen

• Male or female ≥18 years old

• End-stage renal disease on chronic hemodialysis

• Calciphylaxis with active skin lesion(s) of any morphological appearance (includingbut not limited to livedo, induration, ulceration, etc.) and tissue histology reviewconsistent with calciphylaxis diagnosis. Histological features consistent withcalciphylaxis will include soft tissue calcification, microthrombosis, and/orfibrointimal hyperplasia of dermal arterioles

• Acute pain associated with calciphylaxis lesions pain intensity score of ≥ 5 atinitial screening on the modified BPI/SF scale

• Women of childbearing potential must have a pregnancy test (urine or serum [ifanuric]) at screening and not be pregnant and willing to use an acceptable method ofcontraception for the entire duration of the study (3 weeks)

Exclusion Criteria:

• Peritoneal dialysis patients

• Current congestive heart failure exacerbation

• Baseline abnormalities related to QT prolongation (corrected QT interval > 470 ms),hypocalcemia (serum albumin-corrected calcium < 8 mg/dL ), metabolic acidosis (serumbicarbonate < 18 mmol/L, hypotension (resting systolic blood pressure while seated < 80), or interdialytic weight gain ≥ 4.0 kg

• History of ventricular arrhythmias including ventricular fibrillation or ventriculartachycardia associated with shortness of breath, dizziness, hypotension, or syncope

• Any prior (within the past 30 days) or current intravenous Sodium ThiosulfateInjection treatment

• Other investigational agent (drug, biologic, or device) study within the past 30 daysand/or for the duration of the trial

• Pregnant or lactating women

• History of allergy to sulfites, thiosulfate, or any component in Sodium ThiosulfateInjection (sulfa allergy is not an exclusion criterion)

• Significant other acute or chronic concomitant diseases (including but not limited tohepatic, cardiovascular, pulmonary, or oncologic disease, sepsis, pulmonary edema,pulmonary embolism) that would be inconsistent with survival for at least 3 months

• Other serious concurrent or recent medical or psychiatric condition which, in theopinion of the Investigator, makes the patient unsuitable for participation in thisstudy

• Ongoing application of dialysate admixed with iron salt e.g. ferric pyrophosphateduring the entire trial period (patients who are on dialysate admixed with iron saltat screening are eligible if dialysate admixed with iron salt can be substituted withnon-iron based dialysate and patients can be maintained on non-iron based dialysatetherapy for the entire duration of trial period)

• Recent (within 1 week) history of surgical parathyroidectomy or scheduled for surgicalparathyroidectomy during the course of the study

• History of opioid addiction