Among 21 patients with metastatic or unresectable malignancies (comprising five cases of SCNE lung cancer and one case of SCNECC), who were treated with an ATR inhibitor (M6620), three out of the five patients with platinum-refractory SCNE lung cancer had a partial response or prolonged stable disease, lasting 10, ≧ 6, and ≤7 months, respectively [65]. Here, ATR is linked to lung cancer.