A Phase 2a Study Evaluating BIVV020 in Adults With Persistent/Chronic Immune Thrombocytopenia (ITP)

A naive participant was a participant who did not use sutimlimab prior to enrollment. A switcher was a participant who used sutimlimab prior to enrollment. A naive participant was a responder if the platelet count was >=50 × 10^9/liter (L) at >=50 percent (%) of scheduled visits, or for participants with baseline platelet count <15 × 10^9/L, a >=20 × 10^9/L increase in platelet count from baseline at >=50% of scheduled visits, without receiving rescue immune thrombocytopenia (ITP) therapy. A switcher was a responder if the maintenance platelet count was >=30 × 10^9/L at >=50% of scheduled visits, without receiving rescue ITP therapy.

An AE was defined as any untoward medical occurrence in a participant temporally associated with the use of study treatment, whether or not considered related to the study treatment. SAEs were 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 or significant disability/incapacity, was a congenital anomaly/birth defect, was a medically important event. TEAEs were AEs that developed after the first study treatment administration in the safety analysis period which was defined as the period from the first study intervention administration to the end of study (EOS) visit (up to Week 103).

Criteria for potentially clinically significant laboratory abnormalities (PCSA): White blood cells: less than (<)3.0 Giga/L (Non-Black [NB]) or <2.0 Giga/L (Black [B]), greater than or equal to (>=)16.0 Giga/L; Lymphocytes: greater than (>)4.0 Giga/L; Neutrophils: <1.5 Giga/L (NB) or <1.0 Giga/L (B); Monocytes: >0.7 Giga/L; Basophils: >0.1 Giga/L; Eosinophils: >0.5 Giga/L or >upper limit of normal (ULN) (if ULN >=0.5 Giga/L); Hemoglobin: less than or equal to (<=) 115 grams per liter (g/L) (Male[M]) or <=95 g/L (Female[F]), >=185 g/L (M) or >=165 g/L (F), Decrease from baseline (DFB) >=20 g/L; Hematocrit: <=0.37 volume/volume (v/v) (M) or <=0.32 v/v (F); Red blood cells (RBC): >=6 Tera/L; Platelets:<100 Giga/L, >=700 Giga/L. Only the worst case during the treatment-emergent (TE) period for each participant with worsening from baseline is presented.

Criteria for PCSA: Blood Urea Nitrogen: >=17 millimole (mmol)/L; Creatinine: >=150 micromole (mcmol)/L (Adults), >=30% and <100% change from baseline, >=100% change from baseline; Potassium: <3 mmol/L, >=5.5 mmol/L; Sodium: <=129 mmol/L, >=160 mmol/L; Aspartate Aminotransferase (AST): >3 ULN, >5 ULN, >10 ULN, >20 ULN; Alanine Aminotransferase (ALT): >3 ULN, >5 ULN, >10 ULN, >20 ULN; Alkaline Phosphatase (ALP): >1.5 ULN; Bilirubin: >1.5 ULN, >2 ULN; ALT and Total Bilirubin: ALT >3 ULN and TBILI >2 ULN. Only the worst case during the TE period for each participant with worsening from baseline is presented.

The number of participants with PCSA for coagulation parameters during the TE period without PCSA definition by biological function are presented. The parameters evaluated were prothrombin time, prothrombin international normalized ratio and activated partial thromboplastin time (APTT).

Criteria for PCSA: potential of Hydrogen (pH) <=4.6, >=8. Only the worst case during the TE period for each participant with worsening from baseline is presented.

Plasma samples were collected at specified timepoints.

A participant was a responder if the platelet count was >=50 × 10^9/L and there was a greater than 2-fold increase from baseline, measured on 2 occasions at least 7 days apart with the absence of bleeding [bleeding score >=2 on the World Health Organization (WHO) bleeding scale] while the platelet counts were maintained above the threshold and lack of combination ITP therapy during this period. WHO bleeding scores: 1=Petechiae; 2=Mild blood loss; 3=Gross blood loss; and 4=Debilitating blood loss.

Time to first platelet response was defined as greater than or equal to each of the following values: 50 × 10^9/L or 100 × 10^9/L (confirmed by 2 measurements at least 7 days apart). It was calculated as date of first occurrence of confirmed platelet count response before rescue therapy.

Data was collected to assess the effect of treatment with SAR445088 (BIVV020) on the requirement for rescue ITP therapy.

Plasma samples were analyzed for the presence of ADAs for SAR445088 (BIVV020) using validated assays. Treatment-induced ADA was defined as ADAs that developed during the treatment-emergent period and without pre-existing ADA. Pre-existing ADA was defined as ADAs present in samples drawn before first study treatment administration. Treatment-boosted ADA positive was defined as pre-existing ADA (i.e., ADA positive at baseline) that was boosted at least a 9-fold increase of titer values during the treatment-emergent period than the baseline. Treatment-emergent ADA positive was defined as either treatment-induced ADA positive or treatment-boosted ADA positive during the treatment-emergent period. Inconclusive ADA was defined as the one that could not irrefutably be classified as with or without treatment-emergent ADA.