Lung Cancer: Despite early encouraging results, the EGFR inhibitor poziotinib failed to meet its primary endpoint in the phase II ZENITH20 tria

The ZENITH20 trial’s Cohort 1 enrolled a total of 115 patients who received 16 mg/day of poziotinib. The intent-to-treat analysis showed that 17 patients had a response (by RECIST) and 62 patients had stable disease for a 68.7% disease control rate (DCR). The confirmed objective response rate (ORR) was 14.8% (95% Confidence Interval (CI) 8.9%-22.6%). The median duration of response was 7.4 months. The safety profile was in-line with othersecond-generation EGFR tyrosine kinase inhibitors.

While the response rate of Cohort 1 in this trial was lower than we expected, the positive signals observed for this cohort provide support for the continued clinical evaluation of poziotinib in this patient population with significant unmet medical need. We look forward to providing read outs from Cohorts 2 and 3 in 2020, and plan to provide an update on the overall program strategy during the first quarter of 2020 after a full evaluation of the data from Cohort 1 is completed.

The ZENITH20 trial is made up of 7 independent cohorts. Cohorts 1 - 4 are each independently powered for a pre-specified statistical hypothesis with a primary endpoint of ORR. Cohorts 5 - 7 are exploratory studies. The futility analysis has been completed for Cohorts 2 and 3 which met their minimum threshold of responses to continue. The company expects to report results for these cohorts in 2020. Cohorts 4, 5, 6 and 7 are continuing per protocol.

In Cohort 1, poziotinib has shown unequivocal biologic activity. Although we are disappointed by the ORR, we are highly encouraged by other measures including the disease control rate, the duration of response and the predictable safety profile.