PDCD1 and bone sarcoma: The activity of anti-PD1 monotherapy was compared to that of the combined anti-PD1/anti-CTLA-4 treatment in the ALLIANCE A091401 trial, an open-label multicentre US study that randomised patients with advanced soft tissue or bone sarcoma of various histological subtypes to receive nivolumab alone or in combination with ipilimumab [18,19].