Total NPS ranges from 0 to 8 (sum of 0-4 for left and right nasal passage scores per the following criteria), with a lower score indicating smaller-sized nasal polyps: 0 = No polyps; 1 = Small polyps in the middle meatus not reaching below the inferior border of the middle turbinate; 2 = Polyps reaching below the lower border of the middle turbinate (modified to accommodate those with a middle turbinectomy, such that polyp must have reached the top of the inferior turbinate.); 3 = Large polyps reaching the lower border of the inferior turbinate or polyps medial to the middle turbinate; and 4 = Large polyps causing complete obstruction of the inferior nasal cavity. Two blinded primary independent expert readers reviewed every post-screening recorded video endoscopy for a given participant to determine total NPS. A third reader chose one of the two scores to be used for analysis in cases where there was any discrepancy in total NPS assigned between the two primary readers.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

The Nasal Congestion Score (NCS) was assessed daily by the participant via an electronic diary as the response to the following question: Is your nose blocked? The four available response options were scored from 0 (no symptoms) to 3 (severe symptoms): 0 = Not at all; 1 = Mild; 2 = Moderate; and 3 = Severe. For each study day, a score was calculated using an average of the prior 7 days among the available days within the pre-specified window (For Week 24: Study Days 155 to 186), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days; otherwise, the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 168), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

The Sense of Smell Score was assessed daily by the participant via an electronic diary as the response to the following question: Is your sense of smell reduced? The four available response options were scored from 0 (no symptoms) to 3 (severe symptoms): 0 = Not at all; 1 = Mild; 2 = Moderate; and 3 = Severe. For each study day, a score was calculated using an average of the prior 7 days among the available days within the pre-specified window (For Week 24: Study Days 155 to 186), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days; otherwise, the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 168), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

The Posterior Rhinorrhea Score was assessed daily by the participant via an electronic diary as the response to the following question: Do you feel dripping at the back of the nose? The four available response options were scored from 0 (no symptoms) to 3 (severe symptoms): 0=Not at all; 1=Mild; 2=Moderate; and 3=Severe. For each study day, a score was calculated using an average of the prior 7 days among available days within a pre-specified window (For Week 24: Study Days 155 to 186), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days, otherwise the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 168), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

Total NPS ranges from 0 to 8 (sum of 0-4 for left and right nasal passage scores per the following criteria), with a lower score indicating smaller-sized nasal polyps: 0 = No polyps; 1 = Small polyps in the middle meatus not reaching below the inferior border of the middle turbinate; 2 = Polyps reaching below the lower border of the middle turbinate (modified to accommodate those with a middle turbinectomy, such that polyp must have reached the top of the inferior turbinate.); 3 = Large polyps reaching the lower border of the inferior turbinate or polyps medial to the middle turbinate; and 4 = Large polyps causing complete obstruction of the inferior nasal cavity. Two blinded primary independent expert readers reviewed every post-screening recorded video endoscopy for a given participant to determine total NPS. A third reader chose one of the two scores to be used for analysis in cases where there was any discrepancy in total NPS assigned between the two primary readers.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 16 were included in the analysis.

The Nasal Congestion Score (NCS) was assessed daily by the participant via an electronic diary as the response to the following question: Is your nose blocked? The four available response options, scored from 0 (no symptoms) to 3 (severe symptoms) were: 0 = Not at all; 1 = Mild; 2 = Moderate; and 3 = Severe. For each study day, a score was calculated using an average of the prior 7 days among the available days within the pre-specified window (For Week 16: Study Days 99 to 126), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days; otherwise, the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 112), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 16 were included in the analysis.

The SNOT-22 Questionnaire, a disease specific HRQoL measure, comprises a list of 22 symptoms and social or emotional consequences of the nasal disorder. Every participant was asked to rate how severe each problem had been for them over the past 2 weeks on a scale from 0 (no problem at all) to 5 (problem as bad as it can be). The total score is the sum of the scores for all 22 items, ranging from 0 to 110, with a lower score indicating less disease and better HRQoL. A negative score indicates a decrease (or improvement) from the baseline score.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

The Anterior Rhinorrhea Score was assessed daily by the participant via an electronic diary as the response to the following question: Do you have a runny nose? The four available response options were scored from 0 (no symptoms) to 3 (severe symptoms): 0=Not at all; 1=Mild; 2=Moderate; and 3=Severe. For each study day, a score was calculated using an average of the prior 7 days among available days within a pre-specified window (For Week 24: Study Days 155 to 186), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days, otherwise the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 168), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

A participant was considered to have had the event of requiring rescue medication if they had taken systemic corticosteroids for 3 or more consecutive days at any point between randomization and Week 24; if the participant had greater than 155 days of follow-up on study and had not taken systemic corticosteroids for 3 or more consecutive days, then they did not have the event. Participants with less than 155 days of follow-up on the study were classified as having had the event if they discontinued study drug due to adverse event, progressive disease, or lack of efficacy and remained missing; if the participant had less than 155 days of follow-up on study and had not already met these criteria, they were classified as having a missing outcome. The null hypothesis was to be assessed by the Wald Chi-square test of the treatment term in the logistic regression model. If model convergence was an issue, then Fisher's Exact test was to be used.

Full Analysis Set: all participants randomized to study treatment. Only participants on study through Week 24 were included in the analysis.

A participant was considered to have had the event of surgery for nasal polyps if they underwent the procedure at any point between randomization and Week 24; if the participant had greater than 155 days of follow-up on study and had not undergone surgery for nasal polyps, then they did not have the event. Participants with less than 155 days of follow-up on the study were classified as having had the event if they discontinued study drug due to adverse event, progressive disease, or lack of efficacy and remained missing; if the participant had less than 155 days of follow-up on study and had not already met these criteria, they were classified as having a missing outcome. The null hypothesis was to be assessed by the Wald Chi-square test of the treatment term in the logistic regression model. If model convergence was an issue, then Fisher's Exact test was to be used.

Full Analysis Set: all participants randomized to study treatment. Only participants on study through Week 24 were included in the analysis.

The AQLQ is a 32-item participant-reported measure of asthma-related quality of life (QoL) with a total score (the mean of all 32 responses) ranging from 1 (severely impaired) to 7 (not impaired at all); a higher score indicates a better QoL. An increase of at least 0.5 points in the AQLQ score was considered the minimal important difference for improvement in QoL.

Analysis was conducted only in the subgroup of participants with comorbid asthma at screening and AQLQ assessments at Baseline and Week 24.

A participant was considered to have had the event of requiring rescue treatment if they had taken systemic corticosteroids for 3 or more consecutive days or had nasal polypectomy at any point between randomization and Week 24; if the participant had greater than 155 days of follow-up on study and had not received rescue treatment, then they did not have the event. Participants with less than 155 days of follow-up on the study were classified as having had the event if they discontinued study drug due to adverse event, progressive disease, or lack of efficacy and remained missing; if the participant had less than 155 days of follow-up on study and had not already met these criteria, they were classified as having a missing outcome. The null hypothesis was to be assessed by the Wald Chi-square test of the treatment term in the logistic regression model. If model convergence was an issue, then Fisher's Exact test was to be used.

Full Analysis Set: all participants randomized to study treatment. Only participants on study through Week 24 were included in the analysis.

A participant was considered to have had the event of reduction in the need for surgery for nasal polyps if they had a Nasal Polyp Score (NPS) of ≤4 and an improvement in the SNOT-22 score of ≥8.9 (minimal important difference) without rescue treatment at Week 24; if the participant had received rescue treatment or had discontinued study drug due to adverse event, progressive disease, or lack of efficacy and remained missing, then they did not have the event. Participants without an intercurrent event and without valid Week 24 assessments of both NPS and SNOT-22 were classified as having a missing outcome. The null hypothesis was to be assessed by the Wald Chi-square test of the treatment term in the logistic regression model. If model convergence was an issue, then Fisher's Exact test was to be used.

Full Analysis Set: all participants randomized to study treatment. Only participants on study through Week 24 were included in the analysis.

The Total Nasal Symptom Score (TNSS) was defined as the sum of the four individual scores for Nasal Congestion Score, Anterior Rhinorrhea Score, Posterior Rhinorrhea Score, and Sense of Smell Score, ranging from 0 (no symptoms) to 12 (most severe symptoms), assessed daily by the participant via an electronic diary. For each study day, a score was calculated using an average of the prior 7 days among the available days within the pre-specified window (For Week 24: Study Days 155 to 186), excluding the study day itself, if a value had been recorded by the participant on at least 4 of the prior 7 days; otherwise, the 7-day prior average for that study day was to be considered missing. One calculated (non-missing) 7-day prior average was selected for analysis according to the study day with nearest proximity to Week 24 (Study Day 168), with the earlier selected in the case of a tie. Baseline was defined as the (non-missing) 7-day interval ending on the latest day prior to randomization.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

The UPSIT is a 40-question instrument that measures an individual's ability to detect odors and ranges from 0 to 40, with a higher score indicating a better sense of smell. It is a self-administered "scratch-and-sniff" test provided in booklets that have 40 microencapsulated odorants, each with a multiple-choice option for the response. The number of correct responses is summed to provide a total score.

Full Analysis Set: all participants randomized to study treatment. Only participants with assessments at Baseline and Week 24 were included in the analysis.

All adverse events (AE) were treatment emergent AEs, defined as any new AE or any worsening of an existing condition with an onset date on or after the first study drug administration date. AEs were assessed for severity according to the following grading scale: mild (discomfort noticed, but no disruption of normal daily activity), moderate (discomfort sufficient to reduce or affect normal daily activity), or severe (incapacitating with inability to work or to perform normal daily activity). The terms "severe" and "serious" are not synonymous; regardless of severity, some events may have also met seriousness criteria. Multiple occurrences of the same AE in one individual are counted once at the greatest intensity.

Safety Analysis Set: all participants who received at least one dose of study drug, grouped according to treatment received during the treatment period. One participant in the Placebo arm received incorrectly one dose of omalizumab and was included in the Omalizumab arm for safety analyses.

A serious adverse event was defined as any adverse event that met any of the following criteria: was fatal; was life-threatening; required or prolonged inpatient hospitalization; resulted in persistent or significant disability/incapacity; was a congenital anomaly/birth defect in a neonate/infant born to a mother exposed to the study drug; or, was a significant medical event in the investigator's judgment. Multiple occurrences of the same serious adverse event in one individual were counted once.

Safety Analysis Set: all participants who received at least one dose of study drug, grouped according to treatment received during the treatment period. One participant in the Placebo arm received incorrectly one dose of omalizumab and was included in the Omalizumab arm for safety analyses.

Safety Analysis Set: all participants who received at least one dose of study drug, grouped according to treatment received during the treatment period. One participant in the Placebo arm received incorrectly one dose of omalizumab and was included in the Omalizumab arm for safety analyses.

Clinical laboratory tests for serum chemistry and hematology parameters were performed at laboratories; any abnormal values (High or Low) were based on laboratory normal ranges. Laboratory abnormalities are presented by the highest grade according to the World Health Organization (WHO) grade for Adverse Events, except for eosinophils and white blood cells that were graded according to the FDA Toxicity Grading Scale for Healthy Volunteers. Not every abnormal laboratory value qualified as an adverse event, only if it met any of the following criteria: clinically significant (per investigator); accompanied by clinical symptoms; resulted in a change in study treatment; or required a change in concomitant therapy. SGPT/ALT = serum glutamic-pyruvic transaminase/alanine aminotransferase; SGOT/AST = serum glutamic-oxaloacetic transaminase/aspartate aminotransferase

Safety Analysis Set: all participants who received at least one dose of study drug, grouped according to treatment received during the treatment period. One participant in the Placebo arm received incorrectly one dose of omalizumab and was included in the Omalizumab arm for safety analyses.

Serum concentrations of omalizumab were quantified using an enzyme-linked immunoabsorbent assay (ELISA) with a lower limit of quantification (LLOQ) of 28.0 nanograms per millilitre (ng/mL). According to the analysis plan, values below the lower limit of quantification (BLQ) were set to 14 ng/mL (i.e. half of LLOQ value). If one-third or fewer of participants had results that were BLQ, then all summary statistics were to be calculated. However, if more than one-third of participants had results that were BLQ, then the mean and standard deviation were non-reportable and only the median and maximum were to be calculated for that timepoint.

Pharmacokinetics Evaluable Analysis Set: includes participants who received study drug per protocol. Only the omalizumab-treated participants with evaluable samples at each timepoint were included in this analysis.

Serum concentrations of omalizumab were quantified using an enzyme-linked immunoabsorbent assay (ELISA) with a lower limit of quantification (LLOQ) of 28.0 nanograms per millilitre (ng/mL). According to the analysis plan, values below the lower limit of quantification (BLQ) were set to 14 ng/mL (i.e. half of LLOQ value). If one-third or fewer of participants had results that were BLQ, then all summary statistics were to be calculated. However, if more than one-third of participants had results that were BLQ, then the mean and standard deviation were non-reportable and only the median and maximum were to be calculated for that timepoint.

Pharmacokinetics Evaluable Analysis Set: includes participants who received study drug per protocol. Only the omalizumab-treated participants with evaluable samples at each timepoint were included in this analysis.

Serum concentrations of total immunoglobulin E (IgE) and free IgE were measured throughout the 24-week blinded treatment period, as target engagement biomarkers of omalizumab, using validated quantitative immunoassays with lower limits of quantification of 2 and 0.83 International Units per millilitre (IU/mL), respectively, and upper limits of quantification (ULQ) of 5000 and 62.5 IU/mL, respectively. The free IgE assay had limited range to measure circulating levels of free IgE in the presence of complexes of omalizumab-IgE. According to the analysis plan for the free IgE assay, results above ULQ were set to 62.5 IU/mL. If results for one-third or fewer of the participants were greater than the ULQ, then all summary statistics were to be reported. However, if the results for more than one-third of participants were greater than the ULQ, then only the median, interquartile range and minimum were calculated, and the mean, standard deviation, and maximum were non-reportable.

Pharmacokinetics Evaluable Analysis Set: includes participants who received study drug per protocol. The number analyzed includes participants with evaluable samples at each timepoint.

Serum concentrations of total immunoglobulin E (IgE) and free IgE were measured throughout the 24-week blinded treatment period, as target engagement biomarkers of omalizumab, using validated quantitative immunoassays with lower limits of quantification of 2 and 0.83 International Units per millilitre (IU/mL), respectively, and upper limits of quantification (ULQ) of 5000 and 62.5 IU/mL, respectively. The free IgE assay had limited range to measure circulating levels of free IgE in the presence of complexes of omalizumab-IgE. According to the analysis plan for the free IgE assay, results above ULQ were set to 62.5 IU/mL. If results for one-third or fewer of the participants were greater than the ULQ, then all summary statistics were to be reported. However, if the results for more than one-third of participants were greater than the ULQ, then only the median, interquartile range and minimum were calculated, and the mean, standard deviation, and maximum were non-reportable.

Pharmacokinetics Evaluable Analysis Set: includes participants who received study drug per protocol. The number analyzed includes participants with evaluable samples at each timepoint.