Study STX-721-101/PFL-721CI101 is an open label, Phase 1/2 study evaluating the safety, tolerability, pharmacokinetic (PK) exposure, and preliminary antitumor activity of STX-721/PFL-721 in participants with non-small cell lung cancer (NSCLC) carrying EGFR or HER2 exon 20 insertion (ex20ins) mutations.
Has histologically- or cytologically confirmed diagnosis of NSCLC Stage IIIB/C or IV not eligible for curative intent surgery or chemoradiation
Part 1: Tumor tissue EGFR or HER2 exon 20 insertion mutations confirmed by qualified local laboratories. Parts 2 and 3: EGFR/HER2 exon 20 insertion mutations confirmed by qualified local laboratories
Part 1: Has received all approved therapies for advanced or metastatic NSCLC or is ineligible. Part 2 and Part 3: Has received at least 1, but not more than 2, prior lines of approved treatment for advanced or metastatic NSCLC, 1 of which must be platinum-based chemotherapy unless contraindicated
Has documented tumor progression (based on radiological imaging)
Has a tumor that is known to harbor EGFR ex20ins p.H773_V774insH variant, or any EGFR kinase domain activating mutation concurrent with either a T790M and/or C797S resistance mutations
Has history (within ≤2 years before screening) of solid tumor or hematological malignancy that is histologically distinct from NSCLC
Has symptomatic brain or spinal metastases
Has toxicities from previous anticancer therapies that have not resolved to baseline levels or to CTCAE Grade ≤1, except for alopecia and peripheral neuropathy