A Multicenter, Open-label, Non-randomized, Phase 1b/2 Study to Evaluate the Safety, Pharmacokinetics, and Efficacy of Subcutaneous Isatuximab in Adults With Warm Autoimmune Hemolytic Anemia

Part A: Number of Participants With Treatment Emergent Adverse Events (TEAEs) And Treatment Emergent Serious Adverse Events (TESAEs)

Time Frame: From first dose of study drug (Day 1) up to 30 days after last study intervention administration, approximately 101 days

An adverse event (AE) is any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. TEAE is defined as an AE that occurred from the time of the first IMP administration up to 30 days (included) after the last IMP administration. A serious adverse event (SAE) is defined as any untoward medical occurrence that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability/incapacity, was a congenital anomaly/birth defect, was a medically important event.

Part A: Number of Participants With Potentially Clinically Significant Abnormality (PCSA): Hematology

Time Frame: From first dose of study drug (Day 1) up to end of study, approximately 169 days

Blood samples were collected to determine the hematology laboratory significant abnormalities. PCSA values: abnormal values considered medically important by the Sponsor, according to predefined criteria/thresholds based on literature reviews and defined by the Sponsor. Criteria for PCSA: Hemoglobin (Hb): ≤ 115 grams per Liter (g/L) (Male\[M\]); ≤ 95 g/L (Female\[F\]), ≥ 185 g/L (M); ≥ 165 g/L (F), Decrease from baseline ≥ 20 g/L; Hematocrit: ≤ 0.37 volume per volume (v/v) (M); ≤ 0.32 v/v (F), ≥ 0.55 v/v (M); ≥ 0.5 v/v (F); Erythrocyte Count: ≥ 6 x 10\^12 per Liter (/L); Platelet count: \< 100 x 10\^9/L, ≥ 700 x 10\^9/L; Leukocytes: \< 3 x 10\^9/L (Non-Black \[NB\]); \< 2 x 10\^9/L (Black \[B\]), ≥ 16 x 10\^9/L; Neutrophils: \< 1.5 x 10\^9/L (B); \< 1 x 10\^9/L (B); Lymphocytes: \> 4 x 10\^9/L; Monocytes: \> 0.7 x 10\^9/L; Basophils: \> 0.1 x 10\^9/L; Eosinophils: \> 0.5 x 10\^9/L or \> Upper limit of Normal (ULN) (if ULN ≥ 0.5 x 10\^9/L).

Part A: Number of Participants With PCSA: Clinical Chemistry And Electrolyte Parameters

Time Frame: From first dose of study drug (Day 1) up to end of study, approximately 169 days

Blood samples were collected to determine the clinical chemistry laboratory and electrolyte parameters significant abnormalities. PCSA values were defined as abnormal values considered medically important by the Sponsor, according to predefined criteria/thresholds based on literature reviews and defined by the Sponsor. Criteria for PCSA: Glucose: ≤ 3.9 millimoles per Liter (mmol/L) and \< Lower limit of normal (LLN), ≥ 11.1 mmol/L (unfasted); ≥ 7 mmol/L (fasted); Creatinine: ≥ 150 micromoles (µmol)/L, ≥ 30% change from baseline, ≥ 100% change from baseline, Alanine Aminotransferase (ALT): \> 3 ULN, \> 5 ULN, \> 10 ULN; Aspartate Aminotransferase (AST): \> 3 ULN; Alkaline Phosphatase (ALP): \> 1.5 ULN; Total Bilirubin: \> 1.5 ULN, \> 2 ULN; Sodium: ≤ 129 mmol/L, ≥ 160 mmol/L and Potassium: \< 3 mmol/L, ≥ 5.5 mmol/L.

Part B: Overall Response Rate (Response [R] Or Complete Response [CR]) At Day 85

Time Frame: Day 85

Overall response rate was defined as the percentage of participants with a response (R) or complete response (CR) over the evaluable participants. R was defined as an increase in Hb by ≥2 g/dL from baseline and an absence of transfusion in the last 7 days and absence of rescue medications in the past 4 weeks. Biochemical evidence of hemolysis might still be present. CR was defined as Hb ≥11 g/dL (women) or ≥12 g/dL (men), no evidence of hemolysis (normal bilirubin, Lactate dehydrogenase \[LDH\], haptoglobin, and reticulocytes), and absence of transfusion in the last 7 days and absence of rescue medication in the past 4 weeks.

Part A: Number of Participants With Potentially Clinically Significant Abnormality: Vital Signs

Time Frame: From first dose of study drug (Day 1) up to end of study, approximately 169 days

Vital signs were examined to determine the abnormalities. Vital signs included Sitting systolic blood pressure (SSBP), Sitting diastolic blood pressure (SDBP), Sitting heart rate (SHR) and weight. PCSA values were defined as abnormal values considered medically important by the Sponsor, according to predefined criteria/thresholds based on literature reviews and defined by the Sponsor. Criteria for PCSA: SSBP: ≤95 millimeters of mercury (mmHg) and decrease from baseline ≥20 mmHg; ≥160 mmHg and increase from baseline ≥20 mmHg; SDBP: ≤45 mmHg and decrease from baseline ≥10 mmHg, ≥ 110 mmHg and increase from baseline ≥ 10 mmHg; SHR: ≤ 50 beats per minute (bpm) and decrease from baseline ≥ 20 bpm, ≥120 bpm and increase from baseline ≥ 20 bpm; Weight: ≥ 5% decrease from baseline, ≥5% increase from baseline.

Part A: Number of Participants With Potentially Clinically Significant Abnormality: Urinalysis

Time Frame: From first dose of study drug (Day 1) up to end of study, approximately 169 days

Urine samples were collected to determine the urinalysis parameter significant abnormalities. PCSA values were defined as abnormal values considered medically important by the Sponsor, according to predefined criteria/thresholds based on literature reviews and defined by the Sponsor. Criteria for PCSA: pH: ≤ 4.6 or ≥ 8.