The goal of this First-In-Human (FIH) Phase I/II trial is to establish the safety profile, determine the Recommended Phase II Dose (RP2D), explore the pharmacokinetic (PK) exposure and pharmacodynamic (PD) properties as well as assess the efficacy of STX-241/PFL-241, a mutant selective Central Nervous System (CNS)-penetrant fourth generation EGFR TKI, in participants with locally advanced or metastatic NSCLC that progressed during or following third generation EGFR TKI such as osimertinib due to C797X double acquired (secondary) mutations.
Signed and dated informed consent for participation in the trial obtained according to International Council for Harmonisation of Technical Requirements of Pharmaceuticals for Human Use (ICH) Good Clinical Practice (GCP), and national/local regulations.
Male or female ≥ 18 years of age at the time of signing informed consent but at least of legal age in their country.
Histological confirmation of locally advanced or metastatic, EGFR-mutant (ex19del or L858R mutations) non-small cell lung cancer (NSCLC) Stage IIIB/C or IV (AJCC 8th edition) not eligible for curative intent surgery or chemoradiation.
Part 1 Disease progression on a 3rd generation EGFR TKI-based therapy (monotherapy or in combination) received at any prior line of treatment.
Part 1: Participants candidate for targeted therapies available to them (such as but not limited to therapies targeting ALK, BRAF, MET, NTRK, ROS1) as identified by local testing performed after progression to the last line of systemic therapy.
Part 2: Participants who received 1st or 2nd generation EGFR TKIs.
Participant with rapid progressive disease eligible to receive a platinum-based chemotherapy.
Participant unable ingest or digest tablets. This can be caused by any impaired gastrointestinal function or disease, such as for example: ulcerative diseases, malabsorption syndrome, small bowel resection, ileus, etc. or any condition causing uncontrolled nausea, vomiting or diarrhea.