Amgen ($AMGN) and Merck ($MRK) have launched an early-stage trial pairing their respective cancer immunotherapies, looking to confirm the clinical and commercial promise of combination approaches to cancer. The two companies have dosed their first subject in a planned 110-patient trial, administering Amgen's cancer vaccine T-Vec alongside Merck's PD-1-blocking pembrolizumab, approved as Keytruda, to see how well the cocktail can treat melanoma. More