Safety and Efficacy of Efavaleukin Alfa in Subjects With Active Rheumatoid Arthritis

A Phase 1b/2a Study to Evaluate the Safety and Efficacy of Efavaleukin Alfa in Subjects With Active Rheumatoid Arthritis With Inadequate Response to Standard of Care Therapy

Phase 1b. To evaluate the safety and tolerability of subcutaneous (SC) dose administrations of Efavaleukin alfa in subjects with active rheumatoid arthritis (RA). Phase 2a. To evaluate the efficacy of Efavaleukin alfa at week 12 as measured by the American College of Rheumatology 20 percent improvement criteria (ACR 20) in adult subjects with moderate to severe RA.

Matching placebo administered via subcutaneous injection for a total of up to 12 weeks. Participants received placebo in 1 of 2 dosing schedules (i.e. dosing schedule A [less frequent] or schedule B [more frequent]).

A low dose of Efavaleukin alfa administered via subcutaneous injection using dosing schedule A (less frequent than schedule B) for a total of up to 12 weeks.

A high dose of Efavaleukin alfa administered via subcutaneous injection using dosing schedule A (less frequent than schedule B) for a total of up to 12 weeks.

A medium dose of Efavaleukin alfa administered via subcutaneous injection using dosing schedule B (more frequent than schedule A) for a total of up to 12 weeks.

A medium/high dose of Efavaleukin alfa administered via subcutaneous injection using dosing schedule B (more frequent than schedule A) for a total of up to 12 weeks.

Matching placebo administered via subcutaneous injection, depending on the recommended phase 2 dose (RP2D) and dosing schedule as determined in phase 1b, for a total of up to 12 weeks.

Efavaleukin alfa administered via subcutaneous injection depending on the RP2D and dosing schedule determined in phase 1b, for up to a total of up to 12 weeks.

TEAEs were events with an onset after the administration of the first dose of study treatment. TEAEs were graded using the Common Terminology Criteria for Adverse Events (CTCAE). Grade 2 Moderate; minimal, local or noninvasive intervention indicated; limited age appropriate instrumental activities of daily life (ADL). Grade 3 Severe or medically significant but not immediately life-threatening; hospitalization or prolonged hospitalization indicated; disabling; limited self care ADL. Grade 4 Life-threatening consequences; urgent interventions indicated. Serious adverse events (SAEs) were defined as meeting at least 1 of the following criteria: Results in death (fatal) Immediately life-threatening Requires in-patient hospitalization or prolongation of existing hospitalization Results in persistent or significant disability/incapacity Is a congenital anomaly/birth defect Other medically important serious event

Day 1 up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Any changes in systolic/diastolic blood pressure, heart rate, respiratory rate, and temperature that were deemed as clinically significant by the Investigator were reported.

Baseline up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Phase 1b: Number of Participants Who Experienced a Clinically Significant Change in Laboratory Safety Tests

Laboratory safety tests included chemistry and hematology parameters. Clinically significant laboratory safety tests were any events assessed as CTCAE Grade ≥3 at any post-baseline visit. Grade 3 Severe or medically significant but not immediately life-threatening; hospitalization or prolonged hospitalization indicated; disabling; limited self care ADL. Grade 4 Life-threatening consequences; urgent interventions indicated.

Baseline up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Phase 1b: Number of Participants Who Experienced a Clinically Significant Change in Electrocardiograms (ECGs)

Any changes in ECG parameters that were deemed clinically significant by the investigator were reported.

Phase 2a: Number of Participants Who Achieved an American College of Rheumatology 20 Percent Improvement Criteria (ACR 20) at Week 12

ACR 20 response defined as at least 20 percent improvement from baseline in both tender and swollen joint counts, and a 20 percent improvement or more in at least 3 of the following 5 criteria: physician global assessment of disease activity (PGA) subject global assessment of disease activity (SGA) patient global assessment of joint pain subject self-assessment of disability (HAQ-DI) C-Reactive Protein (CRP)

A summary of mean serum concentrations of Efavaleukin alfa over time is presented. Any results below the lower limit of quantification were set to 0.00.

Day 1 (pre-dose), 6 and 12 hours post-dose, and days 2, 3, 4, 8, 11, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78, and Day 85 (pre-dose), 6 and 12 hours post-dose and days 86, 87, 88, 92, 99, 113 and 127

Day 1 (pre-dose) and 6 to 48 hours post-dose, and days 4, 8, 11, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78, Day 85 (pre-dose) and 6 to 72 hours post-dose, and days 92, 99, 113 and 127

Day 1 (pre-dose) and 6 to 48 hours post-dose, and days 4, 8, 11, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78, Day 85 (pre-dose) and 6 to 72 hours post-dose, and days 92, 99, 113 and 127

AUC0-14 was only assessed for the participants who received Efavaleukin alfa using dosing schedule A.

Day 1 (pre-dose) and 6 to 48 hours post-dose, and days 4, 8, 11 and 15, Day 85 (pre-dose) and 6 to 72 hours post-dose, and days 92 and 99

Day 1 (pre-dose) and 6 to 48 hours post-dose, and days 4 and 8, Day 85 (pre-dose) and 6 to 72 hours post-dose, and Day 92

Phase 1b: Number of Participants With Anti-Efavaleukin Alfa Binding Antibodies and Anti-Interleukin (IL-2) Binding Antibodies

Number of participants who tested positive for anti-Efavaleukin alfa binding antibodies and number of those participants who cross-reacted with native human IL-2 (i.e. with anti-IL-2 binding antibodies) are reported.

Baseline up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Phase 1b: Number of Participants With Anti-Efavaleukin Alfa Neutralizing Antibodies and Anti-IL-2 Neutralizing Antibodies

The number of participants who tested positive for anti-Efavaleukin alfa neutralizing antibodies and number of participants with anti-IL2 neutralizing antibodies who tested negative or no result at baseline are reported.

Baseline up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Phase 2a: Number of Participants Who Achieved an American College of Rheumatology 50 Percent Improvement Criteria (ACR 50) or 70 Percent Improvement Criteria (ACR 70) at Week 12

ACR 50 and ACR 70 response defined as at least 50 percent or 70 percent improvement from baseline in both tender and swollen joint counts, and a 50 percent or 70 percent improvement or more in at least 3 of the following 5 criteria: physician global assessment of disease activity (PGA) subject global assessment of disease activity (SGA) patient global assessment of joint pain subject self-assessment of disability (HAQ-DI) C-Reactive Protein (CRP)

Phase 2a: Change From Baseline in Disease Activity Score (28 Joint) Calculated Using The Erythrocyte Sedimentation Rate Formula (DAS28-ESR) at Week 12

Change from baseline in DAS28-ER at Week 12. DAS28-ESR was to assess disease activity in patients with rheumatoid arthritis. DAS28-ESR is a composite score that includes 4 variables: tender joint count (TJC) (based on 28 joints); swollen joint count (SJC) (based on 28 joints); participant's global assessment of health activity using 100 mm VAS: range 0 (no pain) to 100 (maximum pain imaginable); marker of inflammation assessed by ESR in mm/h. DAS28-ESR total score range from 0-10, higher score indicates more disease activity.

Phase 2a: Change From Baseline in Disease Activity Score (28 Joint) Calculated Using the C-reactive Protein Formula (DAS-28-CRP) at Week 12

Change from baseline in DAS28-CRP at Week 12. 2. DAS28-CRP was to assess disease activity in patients with rheumatoid arthritis. DAS28-CRP is a composite score that includes 4 variables: TJC (based on 28 joints); SJC (based on 28 joints); participant's global assessment of health activity using 100 mm VAS: range 0 (no pain) to 100 (maximum pain imaginable); marker of inflammation assessed by CRP in mg/L. DAS28-CRP total score range from 0-10, higher score indicates more disease activity.

TEAEs were events with an onset after the administration of the first dose of study treatment. TEAEs were graded using the Common Terminology Criteria for Adverse Events (CTCAE).

Baseline up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Any changes in systolic/diastolic blood pressure, heart rate, respiratory rate, and temperature that were deemed as clinically significant by the Investigator were reported.

Phase 2a: Number of Participants Who Experienced a Clinically Significant Change in Laboratory Safety Tests

Laboratory safety tests included chemistry and hematology parameters. Clinically significant laboratory safety tests were any events assessed as CTCAE Grade ≥3 at any post-baseline visit. Grade 3 Severe or medically significant but not immediately life-threatening; hospitalization or prolonged hospitalization indicated; disabling; limited self care ADL. Grade 4 Life-threatening consequences; urgent interventions indicated.

Day 1 up to end of study, maximum of 18 weeks (12-weeks double-blind treatment, 6-weeks safety follow-up)

Inclusion Criteria: Subject has provided informed consent prior to initiation of any study specific activities/procedures. Age ≥ 18 to ≤ 70 years of age at screening. A diagnosis of RA consistent with the 1987 or 2010 American College of Rheumatology (ACR)/European League Against Rheumatism classification criteria. Active RA defined as: Phase 1b: DAS-28-CRP > 2.6 at screening. The 28-joint count consists of the finger joints excluding the distal interphalangeal joints, the wrists, elbows, shoulders, and knees. Phase 2a: ≥ 6 swollen joints (based on 66-joint count) and ≥ 6 tender joints (based on 68-joint count) at screening and baseline. The distal interphalangeal joint should be evaluated but not included in the total count to determine eligibility. Additionally, C-reactive protein (CRP) must be greater than the upper limit of normal (ULN) per the central laboratory at screening. Receiving treatment with methotrexate for ≥ 12 weeks and on a stable dose ≥ 15 mg weekly for ≥ 8 weeks prior to day 1. A lower methotrexate dose is acceptable (but no lower than 10 mg weekly) if it is the highest tolerated dose and gastrointestinal or hematologic toxicity at doses ≥ 15 mg weekly is documented by the investigator. Receiving treatment with folic or folinic acid per investigator judgment or according to local standard of care. Phase 1b only: Subject may be receiving a stable dose of leflunomide, sulfasalazine, hydroxychloroquine, minocycline in combination with methotrexate and the dose must be stable for ≥ 8 weeks prior to day 1. Subject may be receiving a stable dose of prednisone ≤ 10mg daily or other equivalent corticosteroid dose and the dose must be stable for ≥ 2 weeks prior today 1. Phase 1b only. Normal or clinically acceptable electrocardiogram (ECG) values (12-lead reporting ventricular rate and PR, QRS, QT and QTc interval) at screening and baseline based on opinion of the investigator. Immunizations (tetanus, diphtheria, pertussis, seasonal influenza [during flu season], and pneumococcal [polysaccharide] vaccinations) up to date per local standards as determined by the investigator. Exclusion Criteria: Class IV RA according to ACR revised response criteria Diagnosis of Felty's Syndrome (RA, splenomegaly and granulocytopenia). Prosthetic joint infection within 3 years of screening or native joint infection within 1 year prior to screening. Active infection (including chronic or localized infections) for which anti-infectives were indicated within 4 weeks prior to day 1 OR presence of serious infection, defined as requiring hospitalization or intravenous anti-infectives within 8 weeks prior to day 1. Known history of active tuberculosis. Positive test for tuberculosis during screening defined as either: positive purified protein derivative (PPD) (≥ 5 mm of induration at 48 to 72 hours after test is placed) OR positive Quantiferon test: a positive PPD and a history of Bacillus Calmette-Guérin vaccination are allowed with a negative Quantiferon test and negative chest x ray; a positive PPD test (without a history of Bacillus Calmette-Guérin vaccination) or a positive or indeterminate Quantiferon test are allowed if they have ALL of the following at screening: no symptoms per tuberculosis or sheet provided by Amgen; document history of a completed course of adequate prophylaxis(completed treatment for latent tuberculosis per local standard of care prior to the start of investigational product); no known exposure to a case of active tuberculosis after most recent prophylaxis; negative chest X-ray. Positive for hepatitis B surface antigen, hepatitis B core antibody (confirmed by hepatitis B deoxyribonucleic acid (DNA) polymerase chain reaction [PCR] test) or detectable hepatitis C virus ribonucleic acid (RNA) by PCR (screening is generally done by hepatitis C antibody [HepCAb], followed by hepatitis C virus RNA by PCR if HepCAb is positive). A history of hepatitis B vaccination without history of hepatitis B is allowed. Phase 1b only: Positive for Human Immunodeficiency Virus (HIV) at screening or known to be HIV positive. Phase 2a only: Known history of HIV Phase 1b only: Positive drug or alcohol urine test for illicit drugs at screening. Prescription medications detected by the drug test are allowed if they are being taken under the direction of a physician. Presence of one or more significant concurrent medical conditions per investigator judgment, including but not limited to the following: poorly controlled diabetes or hypertension; chronic kidney disease stage IIIb, IV, or V; symptomatic heart failure (New York Heart Association class II, III, or IV); myocardial infarction or unstable angina pectoris within the past 12 months prior to randomization; severe chronic pulmonary disease (eg, requiring oxygen therapy); multiple sclerosis or any other demyelinating disease; major chronic inflammatory disease or connective tissue disease other than RA (eg, systemic lupus erythematosus with the exception of secondary Sjögren's syndrome). Malignancy except non-melanoma skin cancers, cervical or breast ductal carcinoma in situ within the last 5 years. History of alcohol or substance abuse within 6 months of screening Phase 1b only: Current smoker, and/or use of any nicotine or tobacco containing products within the last 6 months prior to day 1. These types of products include but are not limited to: snuff, chewing tobacco, cigars, electronic cigarettes, cigarettes, pipes, or nicotine patches. Phase 1b only: Subject unwilling to limit alcohol consumption to ≤ 1 drink of alcohol per day and ≤ 3 drinks per week for the duration of the study, where a drink is equivalent to 12 ounces of regular beer, 8 to 9 ounces of malt liquor, 5 ounces of wine, or 1.5 ounces of 80 proof distilled spirits. Phase 1b only: Unwilling or unable to abstain from alcohol consumption within 48 hours prior to each visit (including screening). Subjects who have received intra-articular or systemic corticosteroid injections for treatment of acute RA flare (not being part of a regular therapeutic regimen) within 4 weeks prior to screening. Currently receiving or had treatment with cyclophosphamide, chlorambucil, nitrogen mustard, or any other alkylating agent ≤ 6 months prior to day 1. Prior treatment with more than a total of 3 therapies that include biologic disease modifying anti-rheumatic drug (DMARDs) or oral synthetic DMARDs (such as tofacinitib, baricitinib). Prior treatment consists of at least 4 doses of a given therapy where the doses were given solely for treatment of RA disease. Prior therapies must not have been used within the following time periods: ≤ 4 weeks prior to day 1 for etanercept and anakinra ≤ 6 months for rituximab ≤ 2 weeks for oral janus kinase inhibitors ≤ 9 weeks prior to day 1 for all therapies not listed above Currently receiving or had treatment with any of the following ≤ 12 weeks prior to day 1: azathioprine cyclosporine gold mycophenolate mofetil Prosorba column Tacrolimus Phase 2a only: Currently receiving or had treatment with leflunomide ≤ 12 weeks prior to day 1 unless an active washout with cholestyramine has been performed. Phase 2a only: Currently receiving or had treatment with any of the following ≤ 4 weeks prior to day 1: hydroxychloroquine sulfasalazine minocycline oral janus kinase inhibitor (eg, tofacitinib, baricitinib) intra-articular, intramuscular or intravenous corticosteroids, including adrenocorticotropic hormone intra-articular hyaluronic acid injections live vaccines -- For Phase 2 only: Unstable dose of non-steroidal anti-inflammatory drugs (NSAID), acetaminophen, and/or analgesics which is taken on an unscheduled basis (ie, not daily or scheduled every certain number of hours) and/or initiated <4 weeks prior to day 1. Received the following within 12 hours prior to screening or day 1: acetaminophen, NSAIDs, tramadol, and/or any narcotic analgesics such as but not limited to hydrocodone, codeine, tramadol, propoxyphene and/or oxycodone (unless in the form of oxycontin). Subject has taken oxycontin within 24 hours prior to screening or day 1. Phase 1b only: Received any herbal medicines (eg St John's wort),or non-vitamin dietary supplements (eg, magnesium) with the exception of calcium within 4 weeks prior to day 1. Currently receiving treatment in another investigational device or drug study, or less than 30 days since ending treatment on another investigational device or drug study(ies). Other investigational procedures while participating in this study are excluded. Presence of laboratory abnormalities at screening including the following: Aspartate aminotransferase (AST) or alanine amino transferase (ALT) at screening > 1.5X upper limit of normal (ULN) Serum total bilirubin (TBL) ≥ 1.5 mg/dL (≥ 26 μmol/L) Hemoglobin ≤ 10.5 g/dL(≤105 g/L) Platelet count < 100,000/mm^3 (<100 x 10^9/L) White blood cell count < 2,500 cells/mm^3 (2.5 x 10^9/L) Absolute neutrophil count (ANC) < 1,000/mm^3 (1.0 x 10^9/L) Calculated glomerular filtration rate of ≤ 50 mL/min/1.73 m^2 using the Modification of Diet in Renal Disease (MDRD) formula Any other laboratory abnormality, which, in the opinion of the investigator, poses a safety risk, will prevent the subject from completing the study, will interfere with the interpretation of the study results, or might cause the study to be detrimental to the subject. Female subject is pregnant or breastfeeding or planning to become pregnant or breastfeed during treatment and for an additional 6 weeks after the last dose of investigational product. Females of child-bearing potential with a positive pregnancy test (assessed by a serum pregnancy test at screening and a urine pregnancy test at baseline). Female subjects of childbearing potential unwilling to use 1 highly effective method of contraception during treatment and for an additional 6 weeks after the last dose of investigational product. Subject has known sensitivity to any of the products or components to be administered during dosing. Subject likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures (eg, Clinical Outcome Assessments [COAs]) to the best of the subject and investigator's knowledge. History or evidence of any other clinically significant disorder, condition or disease (with the exception of those outlined above) that, in the opinion of the investigator or Amgen physician, if consulted, would pose a risk to subject safety or interfere with the study evaluation, procedures or completion

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the link below.