Proof of Concept Study Evaluating the Efficacy and Safety of ATH-063 Treatment in Patients With Relapsed/Refractory Moderately to Severely Active Ulcerative Colitis (UC)

Inclusion Criteria

• •Able to understand and willing to provide informed consent and able to comply with the trial procedures and restrictions.
• •Male or female (assigned at birth, inclusive of all gender identities) participants 18 to 75 years of age, inclusive, at the time of informed consent.
• •Male or female participants must be postmenopausal/surgically sterile, sexually abstinent, or using 2 forms of protocol-specified contraception, including 1 physical barrier method (condom or diaphragm) plus 1 highly effective method (ie, hormonal contraception., intrauterine device, intrauterine hormone-releasing system, bilateral occlusion, vasectomy, or complete sexual abstinence). Women of childbearing potential (WOCBP) must also be nonpregnant and not breastfeeding.
• •Has a diagnosis of UC confirmed by endoscopic and histologic evidence at least 4 months before screening. If confirmation is not available in source documentation, the screening endoscopy and histology reports for this trial may serve as evidence.
• •Has moderately to severely active UC, defined as a UCDSS of 5 to 9, with an EMA subscore of 2 to 3 (obtained during the central review of the screening video endoscopy).
• •Has active UC that extends \>15 cm beyond the anal verge, as identified at the screening colonoscopy.
• •Has documentation of moderately to severely active UC that is refractory (inadequate response - signs and symptoms of persistently active disease despite induction treatment at the approved induction dosing indicated in the product label; or loss of response - recurrence of signs and symptoms of active disease during maintenance dosing following prior clinical benefit \[discontinuation despite clinical benefit does not qualify as having failed biologic therapy\]) to 1 to 2 prior approved biologic/advanced UC therapies (ie, biologic therapies, such as antitumor necrosis factor \[TNF\], anti-integrin, and anti-interleukin \[IL\]-12/23 therapies; or advanced therapies, such as sphingosine 1-phosphate \[S1P\] receptor modulators and Janus kinase \[JAK\] inhibitors \[eg, tofacitinib\]; one of which must have been an anti-TNF therapy; the other, if applicable, may have had the same or a different mechanism of action) when given at doses approved for the treatment of UC.
• •Has documentation of an inadequate response, loss of response, or intolerance to conventional standard-of-care therapy with corticosteroids (ie, prednisone and budesonide), 5-ASAs (ie, mesalamine, sulfasalazine), or other immunomodulators (ie, thiopurines, methotrexate, cyclosporine, and tacrolimus).
• •Any prior therapy, including any investigational drug, not permitted as concomitant standard-of-care therapy must have been discontinued for at least 4 weeks or 5 half-lives prior to screening, whichever is longer, or the participant must have no active drug detected at the start of screening, as determined by therapeutic drug monitoring.
• •Has screening laboratory test results within the following parameters:
• •1. Hemoglobin ≥8 g/dL
• •2. White blood cell (WBC) ≥3×103/μL
• •3. Neutrophil count ≥1.5×103/μL
• •4. Platelet count ≥100,000/μL
• •5. Serum creatinine ≤1.5 mg/dL and/or creatinine clearance \>80 mL/min
• •6. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values must be within 2× the upper limit of normal (ULN) for the laboratory conducting the test
• •7. Total bilirubin ≤1.5×ULN at screening in participants who do not have Gilbert's syndrome
• •8. Total bilirubin ≤2×ULN at screening in participants with Gilbert's syndrome
• •Any current malignancy judged by the investigator not to be in full remission (except for basal cell and in situ squamous cell carcinomas of the skin that have been fully excised and resolved). Prior malignancy must have been in remission for \>2 years prior to screening.
• •Exposure to \>2 prior approved biologic/advanced UC therapies (as defined in Inclusion Criterion) when given at doses approved for the treatment of UC.
• •Use of agents that deplete B or T cells (eg, rituximab) within 12 months of first trial medication administration.
• •Participants with potentially active hepatitis B virus (HBV) infection or at risk of reactivation of HBV infection; hepatitis C virus (HCV) antibody (anti-HCV) or HCV RNA (unless history of HCV that has been cleared and documented with sustained virologic response for \>2 years); or human immunodeficiency virus antibodies (anti-HIV)1/2 at screening.
• •Has severe, progressive, or uncontrolled renal, hepatic, hematologic, endocrine, pulmonary, cardiac, neurologic, psychiatric, or cerebral disease; or signs or symptoms thereof.
• •History of, or concurrent, unstable ischemic heart disease or severe congestive heart failure (New York Heart Association Class III or IV).
• •History of alcohol or drug abuse or dependence within 1 year before screening that, in the opinion of the investigator, would impair the ability of the participant to comply with trial protocol requirements.
• •Female participants who are pregnant, breastfeeding, or planning to become pregnant during the trial.
• •Receiving tube feeding, defined formula diets, or total parenteral alimentation.
• •History of bleeding disorders or recent use of antiplatelet or antithrombotic agents that in the investigator's judgment preclude safely performing endoscopic procedures and biopsy within the timeframe outlined in the trial protocol.
• •Use of drugs that are inhibitors of P-glycoprotein (P-gp; eg, amiodarone, clarithromycin, cyclosporine, ketoconazole, ritonavir, verapamil) or breast cancer resistance protein (BCRP; eg, Cyclosporin A, tacrolimus, gefitinib).
• •Any other condition that precludes adequate understanding, cooperation, and compliance with trial procedures or any condition that could pose a risk to the participant's safety (including any known hypersensitivity to the trial medication products), as per the investigator's judgment.