The HiSCR50 was used for assessing HS treatment effectiveness in controlling inflammatory manifestations in the population. HiSCR50 was defined as >=50% reduction from baseline in the total abscess and inflammatory nodule (AN) count, with no increase from baseline in abscess or draining tunnel count. Baseline was defined as the last available value before the first dose of DB study drug. Percentages are rounded off to the tenth decimal place.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

Time to onset of achieving HiSCR50 during the DB period was defined as the time from randomization to the first time of achieving HiSCR50 by Week 16. HiSCR50 was defined as >=50% reduction from baseline in the total AN count, with no increase from baseline in abscess or draining tunnel count. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

The HiSCR75 was used for assessing HS treatment effectiveness in controlling inflammatory manifestations in the population. HiSCR75 was defined as >=75% reduction from baseline in the total AN count, with no increase from baseline in abscess or draining tunnel count. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

The HiSCR90 was used for assessing HS treatment effectiveness in controlling inflammatory manifestations in the population. HiSCR90 was defined as >=90% reduction from baseline in the total AN count, with no increase from baseline in abscess or draining tunnel count. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

The IHS4 was a validated tool to assess HS severity. The determination of IHS4 required counting inflammatory nodules, abscesses and draining tunnels and multiplying each by a specific coefficient. IHS4 score was calculated as: (number of inflammatory nodules multiplied by 1) + (number of abscesses multiplied by 2) + (number of draining tunnels multiplied by 4). A categorial IHS4 score was derived from this weighted score with total score range: mild: (<=3), moderate: (4 to 10) and severe: (>=11); higher scores indicated worse outcomes. Improvement in IHS4 by >=1 IHS4 stage was considered clinically meaningful.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

The IHS4 was a validated tool to assess HS severity. The determination of IHS4 required counting inflammatory nodules, abscesses and draining tunnels and multiplying each by a specific coefficient. IHS4 score was calculated as: (number of inflammatory nodules multiplied by 1) + (number of abscesses multiplied by 2) + (number of draining tunnels multiplied by 4). A categorial IHS4 score was derived from this weighted score with total score range: mild: (<=3), moderate: (4 to 10) and severe: (>=11); higher scores indicated worse outcomes. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

HS flare was defined as >=25% increase in AN count with a >=2 increase from baseline by Week 16. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

The IHS4 was a validated tool to assess HS severity. The determination of IHS4 required counting inflammatory nodules, abscesses and draining tunnels and multiplying each by a specific coefficient. IHS4 score was calculated as: (number of inflammatory nodules multiplied by 1) + (number of abscesses multiplied by 2) + (number of draining tunnels multiplied by 4). A categorial IHS4 score was derived from this weighted score with total score range: mild: (<=3), moderate: (4 to 10) and severe: (>=11); higher scores indicated worse outcomes. IHS4-55 was defined as a 55% reduction in IHS4 score from baseline. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A.

An AE as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study drug, whether or not considered related to the study drug. An SAE was 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 or significant disability/incapacity, was a congenital anomaly/birth defect or was an important medical event. TEAEs were AEs that developed, worsened or became serious during the TE period. An AESI was an AE (serious or non-serious) of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor was required.

The safety population included for Period A: all randomized participants who had taken at least 1 dose of study drug during Period A, regardless of the amount of study drug administered and for Period B: all randomized participants who continued in Period B and who had taken at least 1 dose of study drug during Period B, regardless of the amount of study drug administered.

The HS-Skin Pain NRS was a unidimensional numeric rating scale (NRS) that allowed for rapid measure of skin pain that was administered multiple times with minimal administrative burden. The HS-Skin Pain NRS had a 24-hour recall period and was completed as a daily diary, ideally at the same time each day (evening) throughout the treatment period. Participants were asked to complete the HS-Skin Pain NRS for 7 consecutive days leading up to the baseline visit with a minimum of 4 completions in their daily diary. The HS-Skin Pain NRS was scored on a 0 to 10 scale; 0: no skin pain and 10: worst skin pain possible. Higher scores indicated worse outcomes. Baseline was defined as the last available value before the first dose of DB study drug.

The biologic and small molecule immunosuppressive-naïve population included all randomized participants in the biologic and small molecule immunosuppressive-naïve subgroup who had taken at least 1 dose of study drug during Period A. Only those participants with Baseline NRS >=3 are reported.

Blood samples were collected at specified timepoints for assessment of serum SAR442970 concentrations.

The pharmacokinetic (PK) population included for Period A: all participants from the safety population of Period A with at least 1 post-Baseline PK result and for Period B: all participants from the safety population of Period B with at least 1 post-Baseline PK result. Only participants with data collected at specified timepoints are reported.

Serum samples were collected at specified timepoints for assessment of anti-SAR442970 antibody response. Treatment-emergent anti-drug antibody (ADA) were defined as participants with at least 1 treatment-induced/boosted ADA at any time after first study drug administration up to the last available ADA sample collection. Number of participants with treatment-emergent ADA response are presented.

All participants from the ADA population, i.e., treated with SAR442970 with at least 1 post-baseline ADA result are included in Part B arm and in Parts A+B arm. The combined ADA analysis provided the accurate summary of all treatment-emergent ADA response in both treatment groups after the initiation of SAR443820.