A Phase 2a Master Protocol Assessing Inebilizumab and Blinatumomab in Autoimmune Diseases

Inclusion Criteria:

• Subprotocol A and B: Diagnosis of SLE according to 2019 European League AgainstRheumatism and the American College of Rheumatology (ACR) classification criteria.

• Subprotocol A and B: Participant must be positive for at least one of the followingautoantibodies at screening (performed by central laboratory) or through documentedhistory:

1. Antinuclear antibodies (ANA) ≥ 1:80

2. Anti-double stranded deoxyribonucleic acid (anti-dsDNA) antibodies elevated toabove normal range (ie, positive results)

3. Anti-Smith antibodies elevated to above normal (ie, positive results).

• Subprotocol A and B (with LN): Active, biopsy-proven, proliferative LN demonstratingclass III or class IV with or without co-existing features of Class V LN (or pureClass V LN for Subprotocol B only) according to 2018 International Society ofNephrology/Renal Pathology Society (ISN/RPS) criteria. The local biopsy report willbe used.

• Subprotocol A and B (with LN): Systemic Lupus Erythematosus Disease Activity Index 2K ≥ 6.

• Subprotocol A and B (with LN): Inadequate response, loss of response or intoleranceto at least 1 therapy (Subprotocol A) or 2 immunosuppressive therapies (SubprotocolB with LN) at the maximally tolerated doses as recommended by the Kidney Disease:Improving Global Outcomes (KDIGO) guidelines (KDIGO, 2024). Inadequate response isdefined as: UPCR ≥ 1.0 mg/mg.

• Subprotocol B (SLE without nephritis): Systemic Lupus Erythematosus Disease ActivityIndex 2K ≥ 6.

• Subprotocol B (SLE without nephritis): Refractory SLE participants with inadequateresponse to multiple therapies (excluding hydroxychloroquine or corticosteroids) andhave failed either a biologic agent or cyclophosphamide.

• Subprotocol A and B: If receiving any of the following medications, participantsmust be on these doses prior to day 1:

1. Prednisone dose ≤ 20 mg/day (or its equivalent in other corticosteroid forms)and at a stable dose for 5 days

2. Hydroxychloroquine dose ≤ 400 mg/day and at a stable dose for 4 weeks. Otherequivalent antimalarials (chloroquine, quinacrine) are also accepted at astable dose for 4 weeks.

3. MMF dose ≤ 3 g/day or MPA dose ≤ 2160 mg/day and at a stable dose for 2 weeks.

4. AZA dose ≤ 2 mg/kg/day and at a stable dose for 2 weeks.

• Subprotocol C: Diagnosis of RA according to the 2010 ACR/ European Alliance ofAssociations for Rheumatology (EULAR) classification criteria.

• Subprotocol C: Moderate to severe disease activity as defined by DAS28-CRP > 3.2with ≥ 3 swollen joints and ≥ 3 tender joints (based on 28 joint counts) atscreening.

• Subprotocol C: Refractory disease defined as:

• Moderate to severe active disease despite having received treatment with:

1. at least 1 conventional synthetic disease-modifying antirheumatic drug (csDMARD), AND

2. at least 2 biologic disease-modifying antirheumatic drugs (bDMARDs) ofdifferent mechanisms of action OR 1 bDMARD and at least 1 targeted syntheticdisease-modifying antirheumatic drugs (tsDMARD).

• Inadequate response or intolerance to csDMARDs, bDMARDs, and tsDMARDs should bedefined as:

1. Participant having active disease despite a minimum of 12 weeks of treatmentwith a csDMARD, bDMARD, or tsDMARD.

2. Intolerance to treatment as defined by participant having experienced anadverse effect from treatment with a csDMARD, bDMARD, or tsDMARD.

Exclusion Criteria:

• Subprotocol A and B: Estimated glomerular filtration rate (eGFR) of < 30 mL perminute per 1.73 m^2 of body surface area (calculated using the Modification of Dietin Renal Disease [MDRD] formula, with screening laboratory results for serumcreatinine value).

• Subprotocol A and B: Significant likely irreversible organ damage related to SLE (eg, end-stage renal disease [ESRD]).

• Subprotocol A and B: Any acute, severe lupus related flare during screening thatneeds immediate treatment.

• Subprotocol A and B: A previous kidney transplant or planned transplant within studytreatment period.

• Subprotocol A and B: History of or current renal diseases (other than LN) that inthe opinion of the investigator could interfere with the LN assessment and confoundthe disease activity assessment (eg, diabetic nephropathy).

• Subprotocol A: Renal biopsy showing pure class V.

• Subprotocol C: Prior history of current inflammatory joint disease other than RAincluding but not limited to systemic lupus erythematosus, mixed connective tissuedisorder, scleroderma, polymyositis, or significant systemic involvement secondaryto RA (eg, vasculitis, pulmonary fibrosis, or Felty's syndrome).

• Subprotocol C: Functional Class IV as defined by the ACR classification offunctional status in RA.