Inclusion Criteria:  Able to comprehend and be willing to sign the Institutional Review Board (IRB)-approved patient prior to administration of any study-related procedures. Patient with HS. Patient must have stable HS. Total abscesses and/or nodule (AN ) count of ≥5 at Baseline visit. HS lesions present in at least 2 distinct anatomical areas at Screening and Baseline. Draining fistula count of ≤20 at Baseline visit. Male or nonpregnant, non-breastfeeding female patients between 18 and 70 years of age, inclusive, at the time of signing the ICF. Female patients of childbearing potential must have a negative serum pregnancy test at Screening and a negative urine pregnancy test prior to dosing on Day 1. Screening laboratory evaluations (hematology, chemistry, coagulation, and urinalysis) must fall within the normal range of the central laboratory's reference ranges unless the results have been determined by the Investigator to not be clinically significant. Fully vaccinated (according to available/applicable national guidelines of the patient's country of residence) against coronavirus disease 2019 (COVID-19).  Exclusion Criteria:  Patient has a history of active skin disease other than HS that could interfere with the assessment of HS. Patient has an uncontrolled non-immunoinflammatory disease that may place the patient at increased risk during the study or impact the interpretation of results, eg, previous malignancy, previous venous thromboembolism. History or evidence of active or latent tuberculosis, irrespective of prior or current treatment status. Known hypersensitivity to ATI-450. Patient is an alcoholic, or has a history of alcoholism, alcoholic liver disease, or other chronic liver disease. Active infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Positive for human immunodeficiency virus (HIV), hepatitis B or C. Patients with serologic evidence of hepatitis B vaccination (hepatitis B surface antibody without the presence of hepatitis B surface antigen) will be allowed to participate. Abnormal lab values as specified in the protocol Any clinically significant laboratory abnormality that would affect interpretation of study data or safety of the patient's participation in the study, per judgment of the Investigator. Clinically significant abnormal findings other than HS from physical examination (PE) conducted at Screening visit (Visit 1) and at Baseline visit (Visit 2) that may affect the interpretation of study data or the safety of the patient's participation in the study, per the judgment of the Investigator. Clinically important history of a medical disorder that would compromise patient safety or data quality, per judgment of the Investigator. Blood pressure levels (in semi-supine position after at least 5 minutes rest): <90 mmHg or >150 mmHg for systolic blood pressure (BP) or <40 mmHg or >90 mmHg for diastolic BP. Patient has experience with >2 biologics, >1 Janus kinase (JAK) inhibitor, or a combination of 1 biologic experience and 1 JAK inhibitor. Patient has taken DMARDS and other prohibited drugs within a defined period of time. Are currently receiving corticosteroids at doses greater than 10 mg per day of prednisone (or equivalent) or have been receiving an unstable dosing regimen of corticosteroids within 2 weeks of the Screening visit. Have been using prescription topical therapies for treatment of HS. Oral or topical tetracycline class antibiotics for treatment of HS are allowable if patient is on a stable dose as specified in the protocol and willing and able to maintain the stable dose for duration of study. Treatment with potent P-glycoprotein inhibitors. Treatment with inhibitors of cytochrome. Patients with history of stroke. Significant active cardiac disease, in the past 6 months, that would affect interpretation of study data or the safety of the patient's participation in the study, per judgment of the Investigator. Patients with abnormal ECG findings. Any dermatologic surgery or procedure in the past 90 days prior to Screening. Known exposure to an individual with a confirmed, active diagnosis of COVID-19 at any time during the Screening Period. Participated in another ATI-450 clinical study. History of clinically significant drug abuse within 2 years prior to Screening. Uncontrolled hypokalemia. Treatment with drugs which prolong the QTc interval and are associated with a known or possible risk of Torsades de Pointes. Treatment with drugs classified as Conditional Drugs for Torsades de Pointes at a steady dose for less than 2 weeks prior to the screening are exclusionary. Patients who have taken these drugs for at least two weeks at a constant dose and meet the ECG criteria can enter the study if they agree to not increase the dose during the study.