Placebo will be administered intravenously or subcutaneously.

The percentage of participants who experienced worsening of mRSS at Week 24 and Week 52 was reported. The worsening of mRSS was defined as an increase from baseline greater than or equal to (>=) 5 points and >=20 percent (%) in mRSS. The mRSS is an accepted clinical measure of skin thickness. The investigator assessed the thickening of the skin using the mRSS through simple palpation on 17 different skin sites in the fingers, hands, forearms, arms, feet, legs, and thighs (bilaterally) and face, chest, and abdomen (singly). Each skin site was rated on a 0 to 3 scale; where 0 = normal skin, 1 = mild thickness, 2 = moderate thickness, and 3 = severe thickness and unable to pinch. Individual skin scores in the 17 body areas were summed and defined as the total mRSS which ranged from 0 (no thickening) to 51 (severe thickening), where higher score indicated more severity of skin thickening/worst outcome.

ACR CRISS is a composite endpoint. Firstly, participants were evaluated on not-improved criterion: new onset of renal crisis, >=15% decline in forced vital capacity [FVC] percent predicted relative to baseline, new onset of pulmonary arterial hypertension, and new onset of left ventricular failure. If yes, these participants were assigned probability score of 0.0. For remaining participants, percentage was based on CRISS domains: mRSS, FVC percent predicted, physician's global assessment, patient's global assessment and Health Assessment Questionnaire Disability-Index (HAQ-DI). Algorithm determines predicted probability of improvement from baseline by incorporating change in mRSS, FVC percent predicted, physician and patient global assessments and HAQ-DI. Outcome was a continuous variable between 0.0 and 1.0 (0 to 100%). Higher score=greater probability of improvement. ACR CRISS score >=0.60 was considered improved, while predicted probability below 0.60 was considered not improved.

FVC was the total amount of air (in liters) exhaled from the lungs during the lung function test measured by spirometer which assessed the change in lung function related to the disease status of an underlying interstitial lung disease.

Change from baseline in the percent predicted FVC at Week 24 and Week 52 was reported. FVC was the total amount of air (in liters) exhaled from the lungs during the lung function test measured by spirometer which assessed the change in lung function related to the disease status of an underlying interstitial lung disease.

DLCO is a measurement of the ability of the lungs to transfer gases from the air to the blood. DLCO is measured using the single breath method. Participants breathe in (inhale) air containing a very small, harmless amount of a tracer gas, such as carbon monoxide. Participants hold their breath for 10 seconds, then rapidly blow it out (exhale). The exhaled gas was tested to determine amount of the tracer gas absorbed during the breath.

Change from baseline in the percent predicted DLCO at Week 24 and Week 52 was reported. DLCO is a measurement of the ability of the lungs to transfer gases from the air to the blood. DLCO is measured using the single breath method. Participants breathe in (inhale) air containing a very small, harmless amount of a tracer gas, such as carbon monoxide. Participants hold their breath for 10 seconds, then rapidly blow it out (exhale). The exhaled gas was tested to determine amount of the tracer gas absorbed during the breath.

Digital ulcers were defined as a full thickness (>3 millimeters [mm] in maximal diameter) skin lesion with loss of epithelium including lesions covered by eschar (excluding pitting scars and hyperkeratotic lesions). Healing was defined by re-epithelialization with loss of pain and exudate. The digital ulcer assessments and counting were performed by the investigator designee.

HAQ-DI assessed the degree of difficulty participants experienced in 8 daily living activity domains during past week: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and common daily activities. Each activity category consisted of 2-3 items. For each item, level of difficulty was scored from 0 to 3 (0=no difficulty, 1=some difficulty, 2=much difficulty, 3=unable to do). Total HAQ-DI score was computed as the sum of domain scores divided by the number of domains answered, providing a score from 0 (no difficulty) to 3 (maximum difficulty), where higher score indicated greater disability.

An adverse event (AE) was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. TEAEs were defined as AEs that occur at or after the initial administration of study intervention. All TEAEs including serious and non-serious events are reported in this outcome measure.

An adverse event (AE) was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. TEAEs were defined as AEs that occurred at or after the initial administration of study intervention. All TEAEs including serious and non-serious events are reported in this outcome measure.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. A SAE was any untoward medical occurrence at any dose that: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/ incapacity, or resulted in congenital anomaly/birth defect. TEAEs were defined as AEs that occur at or after the initial administration of study intervention.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. A SAE was any untoward medical occurrence at any dose that: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/ incapacity, or resulted in congenital anomaly/birth defect. TEAEs were defined as AEs that occur at or after the initial administration of study intervention.

AESI were defined as any newly identified malignancy or case of active tuberculosis (TB) or interstitial lung disease (ILD) occurring after the first study intervention administration in study participants and was reported by the investigator to the sponsor or designee within 24 hours after being made aware of the event. AESIs for this study included drug-induced liver injuries, active TB, ILD, hypersensitivity reaction, opportunistic infection and adverse cardiovascular events.

AESI were defined as any newly identified malignancy or case of active tuberculosis (TB) or interstitial lung disease (ILD) occurring after the first study intervention administration in study participants and was reported by the investigator to the sponsor or designee within 24 hours after being made aware of the event. AESIs for this study included drug-induced liver injuries, active TB, ILD, hypersensitivity reaction, opportunistic infection and adverse cardiovascular events.

Serum concentration of guselkumab was reported. The lower limit of quantification (LLOQ) for guselkumab was 0.01 micrograms per milliliter (mcg/mL).

Serum concentration of guselkumab was reported. The LLOQ for guselkumab was 0.01 mcg/mL.

Number of participants with anti-guselkumab antibody were reported. Serum samples were assessed for anti-drug antibodies.

Number of participants with anti-guselkumab antibody were reported. Serum samples were assessed for anti-drug antibodies.

Participants received placebo (matched to guselkumab 400 mg) IV infusion (induction dosing) at Weeks 0, 4, and 8 followed by placebo (matched to guselkumab 200 mg) SC injection (maintenance dosing) Q4W from Week 12 until Week 48. After Week 52, participants who did not enter LTE underwent the safety follow up until Week 60.

Total of all reporting groups

Participants received placebo (matched to guselkumab 400 mg) IV infusion (induction dosing) at Weeks 0, 4, and 8 followed by placebo (matched to guselkumab 200 mg) SC injection (maintenance dosing) Q4W from Week 12 until Week 48. After Week 52, participants who did not enter LTE underwent the safety follow up until Week 60.

Change from baseline in mRSS at Week 52 was reported. The mRSS is an accepted clinical measure of skin thickness. The investigator assessed the thickening of the skin using the mRSS through simple palpation on 17 different skin sites in the fingers, hands, forearms, arms, feet, legs, and thighs (bilaterally) and face, chest, and abdomen (singly). Each skin site was rated on a 0 to 3 scale; where 0 = normal skin, 1 = mild thickness, 2 = moderate thickness, and 3 = severe thickness and unable to pinch. Individual skin scores in the 17 body areas were summed and defined as the total mRSS which ranged from 0 (no thickening) to 51 (severe thickening), where higher score indicated more severity of skin thickening/worst outcome.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

The percentage of participants who experienced worsening of mRSS at Week 24 and Week 52 was reported. The worsening of mRSS was defined as an increase from baseline greater than or equal to (>=) 5 points and >=20 percent (%) in mRSS. The mRSS is an accepted clinical measure of skin thickness. The investigator assessed the thickening of the skin using the mRSS through simple palpation on 17 different skin sites in the fingers, hands, forearms, arms, feet, legs, and thighs (bilaterally) and face, chest, and abdomen (singly). Each skin site was rated on a 0 to 3 scale; where 0 = normal skin, 1 = mild thickness, 2 = moderate thickness, and 3 = severe thickness and unable to pinch. Individual skin scores in the 17 body areas were summed and defined as the total mRSS which ranged from 0 (no thickening) to 51 (severe thickening), where higher score indicated more severity of skin thickening/worst outcome.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

ACR CRISS is a composite endpoint. Firstly, participants were evaluated on not-improved criterion: new onset of renal crisis, >=15% decline in forced vital capacity [FVC] percent predicted relative to baseline, new onset of pulmonary arterial hypertension, and new onset of left ventricular failure. If yes, these participants were assigned probability score of 0.0. For remaining participants, percentage was based on CRISS domains: mRSS, FVC percent predicted, physician's global assessment, patient's global assessment and Health Assessment Questionnaire Disability-Index (HAQ-DI). Algorithm determines predicted probability of improvement from baseline by incorporating change in mRSS, FVC percent predicted, physician and patient global assessments and HAQ-DI. Outcome was a continuous variable between 0.0 and 1.0 (0 to 100%). Higher score=greater probability of improvement. ACR CRISS score >=0.60 was considered improved, while predicted probability below 0.60 was considered not improved.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

FVC was the total amount of air (in liters) exhaled from the lungs during the lung function test measured by spirometer which assessed the change in lung function related to the disease status of an underlying interstitial lung disease.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

Change from baseline in the percent predicted FVC at Week 24 and Week 52 was reported. FVC was the total amount of air (in liters) exhaled from the lungs during the lung function test measured by spirometer which assessed the change in lung function related to the disease status of an underlying interstitial lung disease.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

DLCO is a measurement of the ability of the lungs to transfer gases from the air to the blood. DLCO is measured using the single breath method. Participants breathe in (inhale) air containing a very small, harmless amount of a tracer gas, such as carbon monoxide. Participants hold their breath for 10 seconds, then rapidly blow it out (exhale). The exhaled gas was tested to determine amount of the tracer gas absorbed during the breath.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

Change from baseline in the percent predicted DLCO at Week 24 and Week 52 was reported. DLCO is a measurement of the ability of the lungs to transfer gases from the air to the blood. DLCO is measured using the single breath method. Participants breathe in (inhale) air containing a very small, harmless amount of a tracer gas, such as carbon monoxide. Participants hold their breath for 10 seconds, then rapidly blow it out (exhale). The exhaled gas was tested to determine amount of the tracer gas absorbed during the breath.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

Digital ulcers were defined as a full thickness (>3 millimeters [mm] in maximal diameter) skin lesion with loss of epithelium including lesions covered by eschar (excluding pitting scars and hyperkeratotic lesions). Healing was defined by re-epithelialization with loss of pain and exudate. The digital ulcer assessments and counting were performed by the investigator designee.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

HAQ-DI assessed the degree of difficulty participants experienced in 8 daily living activity domains during past week: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and common daily activities. Each activity category consisted of 2-3 items. For each item, level of difficulty was scored from 0 to 3 (0=no difficulty, 1=some difficulty, 2=much difficulty, 3=unable to do). Total HAQ-DI score was computed as the sum of domain scores divided by the number of domains answered, providing a score from 0 (no difficulty) to 3 (maximum difficulty), where higher score indicated greater disability.

The FAS included all randomized participants who received at least 1 dose (complete or partial) of study intervention.

An adverse event (AE) was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. TEAEs were defined as AEs that occur at or after the initial administration of study intervention. All TEAEs including serious and non-serious events are reported in this outcome measure.

The safety analysis set included all randomized participants who received at least 1 dose (complete or partial) of study intervention. Participants were analyzed based on the intervention they received, regardless of the intervention groups to which they were assigned.

An adverse event (AE) was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. TEAEs were defined as AEs that occurred at or after the initial administration of study intervention. All TEAEs including serious and non-serious events are reported in this outcome measure.

The safety analysis set for LTE period included all randomized participants who received at least 1 dose (complete or partial) of study intervention during LTE period.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. A SAE was any untoward medical occurrence at any dose that: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/ incapacity, or resulted in congenital anomaly/birth defect. TEAEs were defined as AEs that occur at or after the initial administration of study intervention.

The safety analysis set included all randomized participants who received at least 1 dose (complete or partial) of study intervention. Participants were analyzed based on the intervention they received, regardless of the intervention groups to which they were assigned.

An AE was any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. A SAE was any untoward medical occurrence at any dose that: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/ incapacity, or resulted in congenital anomaly/birth defect. TEAEs were defined as AEs that occur at or after the initial administration of study intervention.

The safety analysis set for LTE period included all randomized participants who received at least 1 dose (complete or partial) of study intervention during LTE period.

AESI were defined as any newly identified malignancy or case of active tuberculosis (TB) or interstitial lung disease (ILD) occurring after the first study intervention administration in study participants and was reported by the investigator to the sponsor or designee within 24 hours after being made aware of the event. AESIs for this study included drug-induced liver injuries, active TB, ILD, hypersensitivity reaction, opportunistic infection and adverse cardiovascular events.

The safety analysis set included all randomized participants who received at least 1 dose (complete or partial) of study intervention. Participants were analyzed based on the intervention they received, regardless of the intervention groups to which they were assigned.

AESI were defined as any newly identified malignancy or case of active tuberculosis (TB) or interstitial lung disease (ILD) occurring after the first study intervention administration in study participants and was reported by the investigator to the sponsor or designee within 24 hours after being made aware of the event. AESIs for this study included drug-induced liver injuries, active TB, ILD, hypersensitivity reaction, opportunistic infection and adverse cardiovascular events.

The safety analysis set for LTE period included all randomized participants who received at least 1 dose (complete or partial) of study intervention during LTE period.

Serum concentration of guselkumab was reported. The lower limit of quantification (LLOQ) for guselkumab was 0.01 micrograms per milliliter (mcg/mL).

Pharmacokinetics analysis set included all participants who received at least 1 complete administration of guselkumab and had at least 1 observed post dose PK data. Here, 'n' (number analyzed) refers to participants evaluable at specified time points. This outcome measure was planned to be analyzed for specified arm only.

Serum concentration of guselkumab was reported. The LLOQ for guselkumab was 0.01 mcg/mL.

Pharmacokinetics analysis set included all participants who received at least 1 complete administration of guselkumab and had at least 1 observed post dose PK data. Here, 'n' (number analyzed) refers to participants analyzed at specified time points.

Number of participants with anti-guselkumab antibody were reported. Serum samples were assessed for anti-drug antibodies.

Immunogenicity analysis set included all participants who received at least 1 administration of guselkumab and had at least 1 observed post dose immune response data. This outcome measure was planned to be analyzed for specified arm only.

Number of participants with anti-guselkumab antibody were reported. Serum samples were assessed for anti-drug antibodies.

Immunogenicity analysis set included all participants who received at least 1 administration of guselkumab and had at least 1 observed post dose immune response data.

Participants received placebo (matched to guselkumab 400 mg) IV infusion (induction dosing) at Weeks 0, 4, and 8 followed by placebo (matched to guselkumab 200 mg) SC injection (maintenance dosing) Q4W from Week 12 until Week 48. After Week 52, participants who did not enter LTE underwent the safety follow up until Week 60.

Participants who received guselkumab and completed the main study (Week 0 through 52, that is, after the Week 48 evaluation, prior to Week 52 evaluation) and who, in the opinion of the investigator benefited from continued treatment, entered LTE period and received guselkumab 200 mg SC injection and placebo IV infusion at Weeks 52, 56, and 60 followed by guselkumab 200 mg SC injection q4w from Week 64 until Week 100. After Week 100, participants were followed up until Week 112.

Participants who received placebo and completed the main study (Week 0 through 52, that is, after the Week 48 evaluation, prior to Week 52 evaluation) and who, in the opinion of the investigator benefited from continued treatment, entered LTE period and received guselkumab 400 mg IV infusion and placebo SC injection at Weeks 52, 56, and 60 followed by guselkumab 200 mg SC injection q4w from Week 64 until Week 100. After Week 100, participants were followed up until Week 112.