In the necitumumab plus gemcitabine and cisplatin group , the number of patients with at least one grade 3 or worse adverse event was higher ( 388 [ 72 % ] of 538 patients ) than in the gemcitabine and cisplatin group ( 333 [ 62 % ] of 541 ) , as was the incidence of serious adverse events ( 257 [ 48 % ] of 538 patients vs 203 [ 38 % ] of 541 ) .