Table 2.

Treatment-Related Adverse Events Across Treatment Phases (As-Treated Population)

Event	Pembrolizumab Group (N = 396)	Placebo Group (N = 399)
	number of participants (percent)
Any treatment-related adverse event	383 (96.7)	379 (95.0)
Grade 3–5 treatment-related adverse event	178 (44.9)	149 (37.3)
Serious treatment-related adverse event	70 (17.7)	57 (14.3)
Treatment-related adverse event that led to death	4 (1.0)*	3 (0.8)†
Treatment-related adverse event that led to discontinuation of all trial treatment	50 (12.6)	21 (5.3)

^*The as-treated population included all the participants who underwent randomization and received at least one dose of pembrolizumab or placebo plus chemotherapy. Treatment-related adverse events were adverse events considered by the investigator to be related to chemotherapy, pembrolizumab, or placebo.

⁺The causes of death were atrial fibrillation (in one participant), immune-mediated lung disease (in one), pneumonia (in one), and sudden cardiac death (in one); All deaths occurred during the neoadjuvant/surgery phase except for the death due to atrial fibrillation, which occurred during the adjuvant phase.

^±The causes of death were acute coronary syndrome (in one participant), pneumonia (in one), and pulmonary hemorrhage (in one); All deaths occurred during the neoadjuvant/surgery phase.