Hope for teens with down syndrome regression disorder: old drugs, new purpose

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Individuals with DS between the ages of 8 and 30 years, inclusive. DS is broadly defined to include complete trisomy 21, Robertsonian translocation trisomy 21, partial trisomy 21 (segmental duplication), and mosaic trisomy 21. * Diagnosis of possible or probable DSRD per 2022 consensus guidelines. * Must agree to random treatment assignment. * Must agree to complete a washout of any medications intended to treat symptoms of DSRD or that may interfere with study interventions. * Must be able to present with a study partner or legal guardian at all study visits. Exclusion Criteria: General * Weight less than 40 kg. * Pregnant or breast feeding. * Past or current tobacco smoking. * Poor venous access not allowing repeated blood tests or non-compliance with venipuncture requirements. * Known allergies, hypersensitivity, or intolerance to lorazepam, IVIG, or tofacitinib. * Participants may be excluded for other unforeseen reasons or confounding reasons for DSRD symptoms at the study doctor's discretion. Co-occurring Conditions * Any co-occurring genetic disorder. * Active symptomatic cardiac disease. * Clinically significant chronic or active viral infection, including but not limited to HIV, hepatitis, CMV, EBV, HSV or untreated tuberculosis. * Untreated chronic or active bacterial infection. * Untreated hypothyroidism or hyperthyroidism. * History of disseminated herpes zoster, disseminated herpes simplex, or recurrent localized dermatomal herpes zoster. * History of malignancy (solid tumor or leukemia). * Moyamoya syndrome or stroke (active or prior). * Baseline abnormal renal function indicative of moderate or severe renal disease by eGFR \<=45. * History of acute narrow-angle glaucoma. * History of venous or arterial thrombosis. * IgA deficiency with antibodies against IgA. * Pathogenic neuronal autoantibody positivity against established causes of autoimmune encephalopathy in CSF. * Any subject with a history of anaphylaxis or a severe systemic response to blood or plasma-derived products. Medications or Interventions * Any vaccination planned during the study or within the last 6 weeks. * Use of electroconvulsive therapy, lorazepam, or a JAK inhibitor within the last 4 weeks. * Use of IVIG within the last 8 weeks. * Use of immunosuppressant drugs (e.g., prednisone, mycophenolate mofetil, azathioprine) within the last 8 weeks. * Use of rituximab within the past 6 months, unless B cell levels have recovered and are above 50 cells/uL. * Use of other immunosuppressant biologics (e.g., adalimumab, etanercept) within the past 6 months. * Use of strong CP3A4 inhibitors or inducers (e.g., ketoconazole, rifampin) within the last 4 weeks. * Use of moderate CP3A4 inhibitors with a strong CYP2C19 inhibitor (e.g., fluconazole) within the last 4 weeks. * Use of moderate CYP2C9 inhibitors (e.g., valproic acid) within the last 4 weeks. * Use of strong CYP1A2 inducers (e.g., phenobarbital) or moderate CYP1A2 inhibitors (e.g., fluvoxamine) within the last 4 weeks. * Use of certain mood stabilizers or anticonvulsants (e.g., clonazepam, lithium, oxcarbazepine) within the last 4 weeks. * Any prior use of methotrexate, cyclophosphamide, or other chemotherapeutics. * Any prior solid organ transplant. * Any prior neurosurgical intervention. * Any subject who has received blood or plasma products ≤ 30 days prior to first Baseline visit.