Multinational, randomized, multicenter, open-label Phase 3 study of 633 participants with advanced, nonsquamous (Stage IV) NSCLC. Participants will be randomized on a 1:1 basis to receive first-line necitumumab plus chemotherapy consisting of pemetrexed and cisplatin in study Arm A, or first-line pemetrexed-cisplatin chemotherapy alone in Arm B.