Retreatment with Erlotinib: Regain of TKI Sensitivity Following a Drug Holiday for Patients with NSCLC Who Initially Responded to EGFR-TKI Treatment

Background: Tyrosine kinase inhibitors (TKI) of the epidermal growth factor receptor (EGFR) are approved as treatment of non-small-cell lung cancer (NSCLC). Despite an initially impressive response to EGFR-TKIs, patients with an activating EGFR mutation invariably relapse. For these patients few treatment options are available after additional progression during or after chemotherapy. The aim of this study is to examine the effect of retreatment with an EGFR-TKI after a drug holiday.

Patients And Methods: We retrospectively reviewed the medical records of 14 patients with stage IV NSCLC who progressed after long-term disease control with EGFR-TKI, who were subsequently treated with standard chemotherapy and at renewed progression retreated with EGFR-TKI.

Results: Fourteen patients (five male, nine female, median age 55 years (39-70 years) received retreatment with erlotinib. The median interval from the discontinuation of EGFR-TKI to the 2nd episode was 9.5 months (3-36 months). Before starting retreatment 36% (n=5) had a T790M mutation. Retreatment resulted in 36% (n=5) partial response, 50% stable disease (n=7) and 14% progressive disease (n=2). Among patients with a T790M mutation this number was two, one and two, respectively. Seven patients are still on therapy without signs of progression. Median follow up is 9 months (1.5-16+months) and median PFS is 6.5 months (1-16+months).

Conclusion: Our findings suggest that retreatment with erlotinib is an option for patients with NSCLC who initially benefited from previous EGFR-TKI treatment and progressed after standard cytotoxic chemotherapy.