- 2 days prior to registration for erlotinib or afatinib, or 3 days for gefitinib if they will be part of the lead-in single dose PF-06747775 PK study (Phase 1 Dose Escalation Single and Multiple dose PK and ECG Assessments; Phase 1 Sildenafil at MTD; and Phase 1b/2 First-Line Single Agent). Please contact the Sponsor for direction for any other EGFR TKI.