Patient description: Patient A is a 30-year-old male who was admitted to the hospital after 10 days of cough, profuse nocturnal sweating and loss of appetite. He had traveled to India 1 months ago and has not any positive history of TB vaccination. He is a previously healthy man, working as an engineer in a high tech company. He doesn't smoke o use any illicit drugs. He was febrile (38 c) with heart rate of 115 b/min, respiratory rate of 22, BP of 125/75 mmHg and O2 sat of 97%. Chest X-ray showed infiltrate in the middle of left lung with diameter of 1.8 cm with signs of cavitation. The sputum smear revealed positive sputum culture for Mycobacterium tuberculosis which are sensitive of the first-line TB drugs (isoniazid, streptomycin, rifampicin and ethambutol). Lab study is reported bellow: Hgb: 13 g/dl WBC: 14000 /mm3 Plt: 300000 /ml AST: 13 U/L ALT: 15 U/L Alk P: 53 U/L Bill total: 0.6 mg/dl Na: 137 mEq/l K: 4 mEq/l Creatinine: 0.5 mg/dl BUN: 10 mg/dl ESR: 120 mm/hr

Clinical trial eligibility criteria: eligible ages (years): 18.0-70.0,  Arthritis, Rheumatoid Healthy Part 1 (phase Ib) (HVs): 1. Healthy males and females according to the investigators assessment, as based on the following a complete medical history including a physical examination, vital signs (BP, PR), 12-lead ECG, and clinical laboratory tests 2. Age >= 18 and <= 60 years 3. Body Mass Index >= 18.5 and <= 29.9 kg/m2 4. Signed and dated written informed consent prior to admission to the study in accordance with GCP and the local legislation 5. Female subjects who meet any of the following from at least 30 days before the first study drug administration and until 30 days after trial completion using adequate contraception, e.g. any of the following methods plus condom: implants, injectables, combined oral contraceptives, intrauterine device (IUD) sexually abstinent have a vasectomised sexual partner (vasectomy at least 1 year prior to enrolment) surgically sterilised (including hysterectomy) postmenopausal defined as at least 1 year of spontaneous amenorrhea (in questionable cases a blood sample with simultaneous levels of follicle stimulating hormone (FSH) above 40 U/L and estradiol below 30 ng/L is confirmatory) Part 2 (phase IIa) (RA Patients): 1. Age >= 18 and <= 70 years 2. Patients classified as having RA according to the 1987 ACR Classification 3. Inadequate clinical response to methotrexate monotherapy defined as moderate/high active disease after oral or s.c. MTX treatment given continuously for at least 3 months and for the last 6 weeks before screening at a stable weekly dose >=15mg. For patients who do not tolerate the minimum weekly dose of at least 15 mg due to side effects, a stable weekly dose as low as 7.5 mg is also permitted. 4. DAS28 4v-CRP >= 3.5 with >= 6 tender and >= 6 swollen joints out of 68/66 joint count at screening and confirmed by >= 6 tender and >= 6 swollen joints out of 68/66 joint count only at randomisation visit (Visit 2) 5. Serum CRP level >= 0.8 mg/dL or ESR >= 28 mm/1h at screening 6. Anti-CCP2 or Rheumatoid Factor positivity as per the limits of used assay at screening 7. Female patients who meet any of the following from at least 30 days before the first study drug administration and until at least 6 months after last dose of MTX taken in the current trial: using adequate contraception, e.g. any of the following methods plus condom: implants, injectables, combined oral contraceptives, intrauterine device (IUD) sexually abstinent have a vasectomised sexual partner (vasectomy at least 1 year prior to enrolment) surgically sterilised (including hysterectomy) postmenopausal defined as at least 1 year of spontaneous amenorrhea (in questionable cases a blood sample with simultaneous levels of follicle stimulating hormone (FSH) above 40 U/L and estradiol below 30 ng/L is confirmatory) OR Male patients who  Part 1 (phase Ib in HVs): 1. Any finding in the medical examination (including BP, PR or ECG) deviating from normal and judged clinically relevant by the investigator 2. Any laboratory value outside the reference range that the investigator considers to be of clinical relevance 3. Any evidence of a concomitant disease judged clinically relevant by the investigator 4. Gastrointestinal, hepatic, renal, respiratory, cardiovascular, metabolic, immunological or hormonal disorders 5. Diseases of the central nervous system (such as epilepsy), other neurological disorders or psychiatric disorders 6. History of relevant orthostatic hypotension, fainting spells, or blackouts 7. History of relevant allergy/hypersensitivity (including allergy to the trial medication or its excipients) 9. Within 10 days prior to administration of trial medication, use of drugs that might reasonably influence the results of the trial 12. Alcohol abuse (consumption of more than 140 g/week in females and 210 g/week in males) 13. Drug abuse or positive drug screen 17. Chronic or relevant acute infections, including but not limited to HIV, Hepatitis B and C and tuberculosis (including a history of clinical TB and/or a positive QuantiFERON TB-Gold test) 18. Subject is assessed by the investigator as unsuitable for e.g. considered not able to understand and comply with study requirements or has a condition that would not allow safe participation in the study 19. Positive pregnancy test, pregnancy or plans to become pregnant within 30 days after study completion 20. Lactation Further applicable for part 1 only are given in the CTP. Part 2 (phase IIa in RA patients): Part 1 (phase Ib) 9, 12, 13 and 17-20 plus: 1. Current or previous use of more than two anti-TNF biologic drugs or use of other biologic agent targeting any other approved mechanism (any biologic drug with mechanism of action other than direct anti-TNF blockade, (e.g. CTLA4, anti-IL6, or anti CD-20) or new oral compounds targeting any other approved mechanism (e.g. JAK inhibitors) for treating RA. 2. Current or previous participation in a clinical trial testing an investigational drug for RA within 3 months prior to screening or within 5 half-lives of the investigational drug, whichever is longer , except of previous participation in trials testing NSAIDs, corticosteroids, analgesics or patients documented as receiving placebo in previous RA trials. 3. DAS28 < 3.2 in at least 2 occasions during the last 6 months before screening 4. RA patients with severe disability (functional class IV) or with confirmed severe systemic manifestations e.g. known amyloidosis, Felty´s syndrome, lymphoproliferative disorders, rheumatoid vasculitis 5. Treatment with any standard DMARD except MTX (including but not limited to sulfasalazine, leflunomide, hydroxychloroquine, D-penicillamine 6. Impaired hepatic function, defined as serum AST/ALT, bilirubin or alkaline phosphatase levels > 2 x ULN 7. Impaired renal function defined as calculated creatinine clearance < 50ml/min 8. Pre-existing blood dyscrasias e.g. bone marrow hypoplasia, significant anaemia, leucopenia or thrombocytopenia 9. Hypersensitivity to MTX or any of its excipients 10. Previous intolerance to MTX as the main cause for stopping treatment (instead of lack of efficacy) 11. Any active or suspected malignancy or history of documented malignancy within the last 5 years before screening, except appropriately treated basal cell carcinoma of the skin or in situ carcinoma of uterine cervix