The trial was conducted in two parts: 1) a 6 patient safety lead-in with 1 dose of 1500mg of durvalumab plus metformin at 500 mg/day and increased to 1,000 mg twice daily over a rapid taper (D/M), and this was followed by 2) a 3:1 randomized trial of D/M (n=29) vs D alone (n=9) (NCT03618654)....WES revealed a correlation between pTE and PIK3CA mutation (amplification) after treatment with D/M (p=0.011)....we report a unique association of between PI3KCa mutation and response.