1. 2 Sec o n d ar y o bjecti ves D ose -fi n di n g a n d D ose -e x p a nsi o n P h ase Sec o n d ar y O bjecti ve: O utc o me Me as ure: T o descri be t he P K of d ur val u ma b a n d tr e m eli m u ma b i n c o m bi nat i o n a n d d ur val u ma b as m o n ot hera p y f ol l o wi n g c o m bi nat i o n t hera p y i n c hil dre n a n d y o u n g a d ul ts wi t h s oli d t u m ors. I n di vi d ual d ur val u ma b a n d tre meli m u ma b c o nce ntrati o ns i n ser u m, a n d P K para meters i ncl u di n g C ma x , C mi n , A U C a n d ot her para m eters w here a p pr o priate. T o deter mi ne t he i m m u n o ge nicit y of d ur val u ma b a n d tre meli m u ma b i n c o m bi nat i o n a n d d ur val u ma b as m o n ot hera p y f ol l o wi n g c o m bi nat i o n t hera p y i n c hil dre n a n d y o u n g a d ul ts wi t h s oli d t u m ors. T o m eas ure effects o n i m m u ne c hec k p o i nt i n hi bit i o n i n res p o nse t o r o uti ne i m m u nizat i o ns ( d ose -e x pa nsi o n p hase o nl y). T o e val uate i m m u ne act i vat i o n a n d c o u nts of nat ural killer ( N K) -, B -a n d T -cells C CI Statistical A nal ysis Pla n St u d y C o de D 4 1 9 E C 0 0 0 0 1 E diti o n N u m ber 4. 0 Date 1 9 A pr 2 0 2 3 C O N FI D E N TI A L A N D P R O P RI E T A R Y 1 2 of 6 5 1.