By Colin Kellaher 



  Surface Oncology Inc. on Wednesday said it would collaborate with Merck & Co. to study its SRF617 investigational antibody therapy in combination with Merck's Keytruda cancer drug in patients with solid tumors. 


  Surface, a Cambridge, Mass., clinical-stage immuno-oncology company, said the companies will study the combination as a component of a first-in-human phase 1/1b study of SRF617. 


  Surface said the study would focus on patients with gastric cancer and those who have developed resistance to checkpoint inhibition, both areas of high unmet need. 


  Shares of Surface, which closed Tuesday at $2.66, surged 42% in premarket trading Wednesday. 


  Write to Colin Kellaher at colin.kellaher@wsj.com