Pelcitoclax with osimertinib achieves 80.8% ORR and 16.4-month mPFS in TKI-naive EGFR-mutated NSCLC
Background
Acquired resistance to Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitors (TKIs) remains a significant challenge in advanced EGFR-mutated non-small-cell lung cancer (NSCLC). While third-generation TKIs like osimertinib improve outcomes, patients eventually progress, necessitating new strategies. The B-cell lymphoma-2 (BCL-2) and BCL-extra-large (BCL-xL) proteins are anti-apoptotic factors often overexpressed in cancer, contributing to drug resistance. Targeting these pathways offers a potential approach to overcome TKI resistance and enhance therapeutic efficacy in NSCLC.
Study Design
This phase 1b trial evaluated the safety and efficacy of pelcitoclax (a BCL-2/BCL-xL inhibitor) combined with osimertinib in 64 patients with EGFR-mutated advanced NSCLC. Patients were divided into three cohorts based on prior TKI treatment. Participants received intravenous pelcitoclax 160 mg (dose-expansion) or 160/240 mg (dose-escalation) weekly, alongside oral osimertinib 80 mg daily. Primary endpoints included safety, recommended phase 2 dose (dose-escalation), and objective response rate (ORR) and safety (dose-expansion).
Results
The study enrolled 64 patients (13 in dose-escalation, 51 in dose-expansion), with 29 in Cohort 1 (3rd-gen TKI + chemotherapy progressed), 8 in Cohort 2 (1st/2nd-gen TKI + chemotherapy progressed), and 27 in Cohort 3 (TKI treatment-naïve). One dose-limiting toxicity occurred at pelcitoclax 240 mg, establishing 160 mg weekly plus osimertinib 80 mg daily as the recommended phase 2 dose. Efficacy varied significantly by cohort:
In TKI treatment-naïve patients (Cohort 3), the
ORRwas 80.8% and median progression-free survival (mPFS) was 16.4 months. For patients previously progressed after third-generation TKI treatment (Cohort 1), theORRwas 10.7% andmPFSwas 2.7 months. Notably,mPFSwas longer in Cohort 1 patients with high expression ofBCL-xL(4.2 vs 2.7 months, p=0.058).
Key Findings
- Pelcitoclax 160 mg weekly + osimertinib 80 mg daily was the recommended phase 2 dose.
- TKI-naïve patients (Cohort 3) achieved an 80.8% objective response rate.
- TKI-naïve patients (Cohort 3) had a median progression-free survival of 16.4 months.
- Patients progressed on 3rd-gen TKI (Cohort 1) had an
ORRof 10.7% andmPFSof 2.7 months. - High
BCL-xLexpression in Cohort 1 correlated with longermPFS(4.2 vs 2.7 months, p=0.058).
Why It Matters
This combination of pelcitoclax and osimertinib offers a promising new therapeutic strategy, particularly for TKI-naïve EGFR-mutated NSCLC patients, where it achieved an impressive 80.8% ORR. For patients who have progressed on third-generation TKIs, the benefit is more modest, but the finding that high BCL-xL expression correlates with longer mPFS suggests a potential biomarker for patient selection. This could lead to personalized treatment protocols, guiding clinicians to identify patients most likely to benefit from BCL-xL inhibition in combination with osimertinib. Further research is needed to translate these findings into a widely adopted clinical protocol, especially for resistant cases, and to fully explore the role of BCL-xL as a predictive marker.
pelcitoclax
osimertinib
nsclc
egfr-mutation
bcl-2-inhibitor
bcl-xl-inhibitor