Efficacy and safety of osimertinib in a Japanese compassionate use program

Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that targets the T790M mutation of EGFR. In 2016, AstraZeneca conducted a compassionate use program for osimertinib in Japan.

Eighteen consecutive patients with histologically proven non-small-cell lung cancer (NSCLC) and harboring the T790M EGFR mutation participated in the compassionate use program between 1 April and 25 May 2016, at the National Cancer Center Hospital. We examined the efficacy and safety of osimertinib in a compassionate use program.

All patients had been previously treated with both cytotoxic chemotherapy and EGFR TKIs. Overall response rate was 62.5% (95% confidence interval (CI): 35.9-89.1%). Among the six patients pretreated with a third-generation EGFR TKI, two (33%) responded to osimertinib. On administration with osimertinib, median progression-free and overall survival rates at six months were 66.7% (95% CI: 44.9-88.5) and 88.9% (95% CI: 74.4-100), respectively. Although the toxicity of osimertinib was mild in most patients, three patients had severe adverse events: two developed interstitial lung disease (ILD) and one developed Grade 3 hepatotoxicity. Among these, two (33%) of the six patients who received osimertinib following nivolumab treatment developed severe adverse events, with one each developing Grade 3 hepatotoxicity and Grade 3 ILD. Only one patient visited our hospital seeking to participate in the compassionate program from another hospital.

Osimertinib demonstrated efficacy even in patients with heavily pretreated NSCLC harboring the T790M mutation. Some patients pretreated with another third-generation EGFR TKI also responded to osimertinib.