Treatment of Alopecia Areata (AA) With Dupilumab in Patients With and Without Atopic Dermatitis (AD)

Inclusion Criteria: * Male or female subjects who are at least 18 years old at the time of informed consent. * Subject is able to understand and voluntarily sign an informed consent document prior to participation * Subject is able to adhere to the study visit schedule and other protocol requirements. * Females of childbearing potential (FCBP) must have a negative pregnancy test at Screening and Baseline. While on investigational product and for at least 28 days after taking the last dose of investigational product (IP), FCBP who engage in activity in which conception is possible must use one of the approved contraceptive options described below: 1. Option 1: Any one of the following highly effective methods: hormonal contraception (oral, injection, implant, transdermal patch, vaginal ring); intrauterine device (IUD); tubal ligation; or partner's vasectomy; OR 2. Option 2: Male or female condom (latex condom or non-latex condom NOT made out of natural \[animal\] membrane \[for example, polyurethane\]); PLUS one additional barrier method: (a) diaphragm with spermicide; (b) cervical cap with spermicide; or (c) contraceptive sponge with spermicide. * If subject is a female of non-childbearing potential, she must have documented history of infertility, be in a menopausal state for one year, or had a hysterectomy, bilateral tubal ligation, or bilateral oophorectomy. * Subject has a history of at least 6 months of moderate to severe AA (≥ 30% scalp involvement) as measured using the SALT score; OR subject has ≥ 95% loss of scalp hair for enrollment as AA totalis (AT) or universalis (AU) subtypes. 1. AT and AU will be limited to 50% of the total number of subjects enrolled. 2. One-third of subjects must have active AD skin or a concomitant history of AD at the time of the Screening and Baseline visits. * Subject has a negative Tuberculin purified protein derivative (PPD) or QuantiFERON TB-Gold test (QFT) prior to baseline. Subjects with a positive or indeterminable PPD or QFT result must have a documented negative workup for tuberculosis and/or completed standard tuberculosis therapy. * Subjects must meet the following laboratory criteria: 1. White blood cell count ≥ 3000/mm3 (≥ 3.0 x 109/L) and \< 14,000/mm3 (≤ 14 x 109/L). 2. Platelet count ≥ 100,000/μL (≥ 100 x 109/L). 3. Serum creatinine ≤ 1.5 mg/dL (≤ 132.6 μmol/L). 4. AST (SGOT) and ALT (SGPT) ≤ 2 x upper limit of normal (ULN). If the initial test shows ALT or AST \> 2 times the ULN, one repeat test is allowed during the Screening Phase. 5. Total bilirubin ≤ 2 mg/dL (34 μmol/L). If the initial test shows total bilirubin \> 2 mg/dL (34 μmol/L), one repeat test is allowed during the Screening Phase. 6. Hemoglobin ≥ 10 g/dL (≥ 6.2 mmol/L). * Subject is judged to be in otherwise good overall health following a detailed medical and medication history, physical examination, and laboratory testing. Exclusion Criteria: * Subject is pregnant or breastfeeding. * Subject's cause of hair loss is indeterminable and/or they have concomitant causes of alopecia, such traction, cicatricial, pregnancy-related, drug-induced, telogen effluvium, or advanced androgenetic alopecia (i.e. Ludwig Type III or Norwood-Hamilton Stage ≥ V). * Subject has a history of AA with no evidence of hair regrowth for ≥ 10 years since their last episode of hair loss. * Subject has an active bacterial, viral, or helminth parasitic infections; OR a history of ongoing, recurrent severe infections requiring systemic antibiotics * Subject with a known or suspected underlying immunodeficiency or immune-compromised state as determined by the investigator. * Subject has a concurrent or recent history of severe, progressive, or uncontrolled renal, hepatic, hematological, intestinal, metabolic, endocrine, pulmonary, cardiovascular, or neurological disease. * Active hepatitis B, hepatitis C, human immunodeficiency virus (HIV), or positive HIV serology at the time of screening for subjects determined by the investigators to be at high-risk for this disease. * Subject has a suspected or active lymphoproliferative disorder or malignancy; OR a history of malignancy within 5 years before the Baseline assessment, except for completely treated in situ non-melanoma skin and cervical cancers without evidence of metastasis. * Subject has received a live attenuated vaccine ≤ 30 days prior to study randomization. * Subject has any uncertain or clinically significant laboratory abnormalities that may affect interpretation of study data or endpoints. * Subject has any other medical or psychological condition that, in the opinion of the investigator, may present additional unreasonable risks as a result of their participation in the study and/or interfere with clinic visits and necessary study assessments. * History of adverse systemic or allergic reactions to any component of the study drug. * Severe, untreated asthma or a history of life-threatening asthma exacerbations while on appropriate anti-asthmatic mediations. * Use of systemic immunosuppressive medications, including, but not limited to, cyclosporine, systemic or intralesional corticosteroids, mycophenolate mofetil, azathioprine, methotrexate, tacrolimus, or ultraviolet (UV) phototherapy with/without Psoralen Ultraviolet A (PUVA) therapy within 4 weeks prior to randomization. * Use of an oral JAK inhibitor (tofacitinib, ruxolitinib) within 12 weeks prior to the Baseline visit. * Subject has used topical corticosteroids, and/or tacrolimus, and/or pimecrolimus within 1 week before the Baseline visit. * Subject has been previously treated with dupilumab. * Subject currently uses or plans to use anti-retroviral therapy at any time during the study.