| E.1 Medical condition or disease under investigation | 
| E.1.1 | Medical condition(s) being investigated  | 
| ST-elevation myocardial infarction | 
 
 
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| E.1.1.1 | Medical condition in easily understood language  | 
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| E.1.1.2 | Therapeutic area  | Diseases [C] - Cardiovascular Diseases [C14] | 
| MedDRA Classification | 
| E.1.2 Medical condition or disease under investigation | 
| E.1.2 | Version  | 20.0 | 
 
| E.1.2 | Level  | LLT | 
 
| E.1.2 | Classification code  | 10064345 | 
 
| E.1.2 | Term  | ST segment elevation myocardial infarction | 
 
| E.1.2 | System Organ Class  | 100000004849 | 
 
 
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| E.1.3 | Condition being studied is a rare disease  |  No  | 
| E.2 Objective of the trial | 
| E.2.1 | Main objective of the trial  | 
| The primary objective is to compare the effect of a single injection of two doses of rituximab versus placebo on 6 months left ventricular systolic function, using CMR, in patients who have had an acute anterior STEMI | 
 
 
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| E.2.2 | Secondary objectives of the trial  | 
The secondary endpoints will be assessed by comparing the effects of rituximab versus placebo on: 
 
 •	Infarct size by CMRI (using T1-weighted late gadolinium enhancement, LGE) between day 3 and day 7 (52) and at 6 months. 
 •	Edema extension by CMRI (using T2W) between day 3 and day 7 (5±2) 
 •	T2 relaxation time at ischemic region by CMRI (using T2 mapping) between day 3 and day 7 (5±2) 
 •	Microvascular obstruction by CMRI (hypointense areas within LGE) between day 3 and day 7 (5±2) 
 •	NT-pro-BNP at 6 months 
 •	Any adverse event related to treatment
 
 | 
 
 
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| E.2.3 | Trial contains a sub-study  |  No  | 
| E.3 | Principal inclusion criteria  | 
•	Age 18-75 (women must be either postmenopausal defined as being amenorrhoeic for greater than 2 years with an appropriate clinical profile, e.g. age appropriate (>55 years old), history of vasomotor symptoms) or having documented hysterectomy and/or bilateral oophorectomy) ;
 •	Clinical evidence at presentation of anterior ST-elevation myocardial infarction (STEMI) defined as symptoms suggestive of acute myocardial ischemia, an electrocardiogram showing ST-segment elevation ≥2 mm in ≥2 contiguous leads in V1 to V4;
 •	Complete occlusion (i.e. TIMI flow 0-1) of proximal or mid left anterior descending (LAD) coronary artery on urgent angiography interpreted as the infarct-related artery (IRA);
 •	Onset of worse symptoms within 6 hours before admission;
 •	Plan to provide primary percutaneous angioplasty (PPCI) for the patient within 2 hours of ECG diagnosis ;
 •	Ability to start infusion of rituximab within 3 hours of PPCI ;
 •	Written informed consent. | 
 
 
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| E.4 | Principal exclusion criteria | 
•	History of previous MI 
 •	Presentation with cardiac arrest
 •	Cardiogenic shock (defined as systolic blood pressure <90 mmHg for >30minutes, or necessitating vasopressors to achieve a blood pressure ≥90 mmHg) 
 •	Cardiac electrical instability (defined as complete heart block needing temporary pacing or any tachyarrhythmia needing cardioversion) 
 •	Patients with Killip class III heart failure
 •	History of severe chronic renal failure (define as stage 4 (GFR = 15-29 mL/min) or worse)
 •	History of hepatitis B, HIV or tuberculosis
 •	Patient positive for point of care bedside test of Ag HBs 
 •	Current infections 
 •	Presence, or history in ≤ five years, of an ongoing cancer, (except in situ cancer of the cervix or basal cell carcinoma)
 •	QTcF> 450 msecs in males, > 470msecs in females  
 •	Any oral or intravenous immunosuppressive treatment, immune modulatory monoclonal antibodies or immunodepleting therapy at any time (inhalers and topical creams with corticosteroids are permitted)
 •	Previous history of major organ transplant including renal transplant
 •	Known hypersensitivity to the active substance of Mabthera® (rituximab) or to proteins of murine origin, or to any of the other excipients
 •	Expected need for vaccination with a live attenuated vaccine during the study, including incomplete vaccination courses (in case, life, attenuated vaccine must be administered at least 30 days before inclusion in study)
 •	Absence of COVID-19 vaccination (at least one dose of COVID-19 vaccination is needed for inclusion at least 4 weeks before inclusion in the study)
 •	Any obvious contraindications for MRI or conditions which will impede image acquisition 
 •	Known hepatic failure
 •	Previous history of progressive multifocal leukoencephalopathy 
 •	Inclusion in other interventional drug study within the previous 3 months
 •	Inability to comply with study procedures | 
 
 
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| E.5 End points | 
| E.5.1 | Primary end point(s) | 
| The primary endpoint is the left ventricular ejection fraction (LVEF) by CMR at 6 months | 
 
 
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| E.5.1.1 | Timepoint(s) of evaluation of this end point | 
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| E.5.2 | Secondary end point(s) | 
The secondary endpoints will be assessed by comparing the effects of rituximab versus placebo on: 
 
 •	Infarct size by CMRI (using T1-weighted late gadolinium enhancement, LGE) between day 3 and day 7 (52) and at 6 months. 
 •	Edema extension by CMRI (using T2W) between day 3 and day 7 (5±2) 
 •	T2 relaxation time at ischemic region by CMRI (using T2 mapping) between day 3 and day 7 (5±2) 
 •	Microvascular obstruction by CMRI (hypointense areas within LGE) between day 3 and day 7 (5±2) 
 •	NT-pro-BNP at 6 months 
 •	Any adverse event related to treatment
 
 | 
 
 
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| E.5.2.1 | Timepoint(s) of evaluation of this end point | 
 | 
| E.6 and E.7 Scope of the trial | 
| E.6 | Scope of the trial | 
| E.6.1 | Diagnosis |  No  | 
| E.6.2 | Prophylaxis |  No  | 
| E.6.3 | Therapy |  Yes  | 
| E.6.4 | Safety |  No  | 
| E.6.5 | Efficacy |  Yes  | 
| E.6.6 | Pharmacokinetic |  No  | 
| E.6.7 | Pharmacodynamic |  No  | 
| E.6.8 | Bioequivalence |  No  | 
| E.6.9 | Dose response |  No  | 
| E.6.10 | Pharmacogenetic |  No  | 
| E.6.11 | Pharmacogenomic |  No  | 
| E.6.12 | Pharmacoeconomic |  No  | 
| E.6.13 | Others |  No  | 
| E.7 | Trial type and phase | 
| E.7.1 | Human pharmacology (Phase I) |  No  | 
| E.7.1.1 | First administration to humans |  No  | 
| E.7.1.2 | Bioequivalence study |  No  | 
| E.7.1.3 | Other |  No  | 
| E.7.1.3.1 | Other trial type description |  | 
| E.7.2 | Therapeutic exploratory (Phase II) |  Yes  | 
| E.7.3 | Therapeutic confirmatory (Phase III) |  No  | 
| E.7.4 | Therapeutic use (Phase IV) |  No  | 
| E.8 Design of the trial | 
| E.8.1 | Controlled |  Yes  | 
| E.8.1.1 | Randomised |  Yes  | 
| E.8.1.2 | Open |  No  | 
| E.8.1.3 | Single blind |  No  | 
| E.8.1.4 | Double blind  |  Yes  | 
| E.8.1.5 | Parallel group |  Yes  | 
| E.8.1.6 | Cross over  |  No  | 
| E.8.1.7 | Other |  No  | 
| E.8.2 |  Comparator of controlled trial | 
| E.8.2.1 | Other medicinal product(s) |  No  | 
| E.8.2.2 | Placebo  |  Yes  | 
| E.8.2.3 | Other |  Yes  | 
| E.8.2.3.1 | Comparator description | 
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| E.8.2.4 | Number of treatment arms in the trial | 3 | 
| E.8.3 | 
                                The trial involves single site in the Member State concerned
                             |  No  | 
| E.8.4 |  The trial involves multiple sites in the Member State concerned  |  Yes  | 
| E.8.4.1 | Number of sites anticipated in Member State concerned | 20 | 
| E.8.5 | The trial involves multiple Member States |  Yes  | 
| E.8.5.1 | Number of sites anticipated in the EEA | 10 | 
| E.8.6 Trial involving sites outside the EEA | 
| E.8.6.1 | Trial being conducted both within and outside the EEA |  Yes  | 
| E.8.6.2 | Trial being conducted completely outside of the EEA |  No  | 
| E.8.6.3 | If E.8.6.1 or E.8.6.2 are Yes, specify the regions in which trial sites are planned | 
| Israel | 
 
| Germany | 
 
| Netherlands | 
 
| Spain | 
 
| Sweden | 
 
| United Kingdom | 
 
| Czechia | 
 
 
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| E.8.7 | Trial has a data monitoring committee |  Yes  | 
| E.8.8 | 
                        Definition of the end of the trial and justification where it is not the last
                        visit of the last subject undergoing the trial
                     | 
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| E.8.9 Initial estimate of the duration of the trial | 
| E.8.9.1 | In the Member State concerned years | 4 | 
| E.8.9.1 | In the Member State concerned months | 4 | 
| E.8.9.1 | In the Member State concerned days |  | 
| E.8.9.2 | In all countries concerned by the trial years | 4 | 
| E.8.9.2 | In all countries concerned by the trial months | 4 |