A Phase 1/2 Study to Assess BDTX-1535, an Oral EGFR Inhibitor, in Patients with Glioblastoma or Non-Small Cell Lung Cancer

BDTX-1535-101 is an open-label, Phase 1 dose escalation and Phase 2 multiple cohort study
designed to evaluate the safety, pharmacokinetics (PK), optimal dosage, central nervous
system (CNS) activity, and antitumor activity of BDTX-1535. The study population
comprises adults with either advanced/metastatic non-small cell lung cancer (NSCLC) with
non-classical or acquired epidermal growth factor receptor (EGFR) resistance (EGFR C797S)
mutations with or without CNS disease (in Phase 1 and Phase 2), or glioblastoma (GBM)
expressing EGFR alterations (Phase 1 only). All patients will self-administer BDTX-1535
monotherapy by mouth in 21-day cycles.

Phase 1 enrollment is now complete. Phase 2 is currently enrolling.

Phase 2 Eligibility:

Key Inclusion Criteria Required for locally advanced or metastatic NSCLC:

- Measurable disease by RECIST 1.1 criteria.

- Adequate bone marrow or organ function.

- Life expectancy of ≥ 3 months.

- Sufficient performance status.

- Confirmed NSCLC, without small cell lung cancer transformation with or without brain
metastases.

- Disease progression following or intolerance of standard of care (excluding patients
in the treatment-naïve non-classical driver cohort):

- Cohort 1 (Non-Classical driver cohort): Advanced/metastatic NSCLC with a
non-classical driver EGFR mutation (eg, G719X) following up to 2 lines of
therapy with only 1 prior EGFR TKI regimen (third-generation preferred; other
approved EGFR TKI acceptable).

- Cohort 2 (Acquired resistance C797S cohort): Advanced/metastatic NSCLC with the
acquired resistance C797S EGFR mutation following up to 2 lines of therapy,
including only one EGFR TKI, which must be a third generation EGFR TKI (eg,
osimertinib).

- Cohort 3 (First-line non-classical driver cohort): Treatment-naïve
advanced/metastatic NSCLC with a non-classical driver EGFR mutation (1 cycle of
chemotherapy or immune checkpoint inhibitor are permitted). Patients with
co-occurring L858R mutations and a non-classical mutation are eligible for
inclusion.

- Identification of one (or more) of the following EGFR mutations by Next Generation
Sequencing (NGS) as determined by a local assay performed in a validated laboratory
in the absence of other known resistance mutations (eg, T790M, MET):

- Non-classical driver EGFR mutations (eg, L861R, S768I, G719X).

- EGFR acquired resistance mutation (eg, C797S) to a 3rd generation EGFR TKI.

- For Phase 2, dose expansion, patients in Cohort 1 who received 3rd generation
EGFR TKI (eg, osimertinib), the NGS report within 6 months prior to the start
of Screening is acceptable. For patients in Cohort 2, the NGS report must be
from the last disease progression on the immediate prior therapy. For patients
in Cohort 3, the NGS report must be at the time of diagnosis.

Key Exclusion Criteria:

- Known resistant mutations in tumor tissue or by liquid biopsy (eg, T790M, MET).

- Received more than 1 EGFR TKI therapy (ie, erlotinib or gefitinib) for the treatment
of metastatic or recurrent EGFR NSCLC.

- Any history of interstitial lung disease related to EGFR TKI use.

- Symptomatic or radiographic leptomeningeal disease.

- Symptomatic brain metastases or spinal cord compression requiring urgent clinical
intervention.

- Unresolved toxicity from prior therapy.

- Significant cardiovascular disease.

- Major surgery within 4 weeks of study entry or planned during study.

- Ongoing or recent anticancer therapy or radiation therapy.

- Evidence of malignancy (other than study-specific malignancies) requiring active
therapy within the next 2 years.

- Active hepatitis B or C infection and/or known human immunodeficiency virus (HIV)
carrier.

- Poorly controlled gastrointestinal disorders.