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OA 12 - Emerging Genomic Targets (ID 679)
- Event: WCLC 2017
- Type: Oral
- Track: Advanced NSCLC
- Presentations: 1
OA 12.01 - The Preclinical and Clinical Activity of Poziotinib, a Potent, Selective Inhibitor of EGFR Exon 20 Mutant NSCLC (ID 10369)
11:00 - 12:30 | Author(s): J. Kurie
Approximately 10% of EGFR mutant NSCLCs have an insertion/mutation in exon 20 of EGFR resulting in primary resistance to currently available tyrosine kinase inhibitors (TKIs). We previously reported that the structural features of poziotinib could potentially enable it to circumvent the steric hindrance induced by exon 20 mutations. Here we further characterize the preclinical activity of poziotinib and report on initial clinical activity of poziotinib in patients with EGFR exon 20 mutations from an ongoing phase II study.
We evaluated poziotinib activity in vitro using human NSCLC cell lines and the BAF3 model as well as several patient-derived xenograft (PDX) models and genetically engineered mouse models (GEMMs) of exon 20 insertion. We launched a phase 2 investigator-initiated trial of poziotinib in patients with metastatic NSCLC with EGFR exon 20 insertions (NCT03066206).
In vitro poziotinib was approximately 100x more potent than osimertinib and 40x more potent than afatinib against a common panel of EGFR exon 20 insertions. Furthermore, it had ~65-fold greater potency against common exon 20 insertions compared with EGFR T790M mutations; 3[rd] generation inhibitors osimertinib, EGF816, and rociletinib were all significantly less potent for exon 20 mutations/insertions compared with T790M. in vivo poziotinib led to >85% reduction in tumor burden in GEM models of EGFR exon 20 insertion (D770insNPG) NSCLC and the PDX model LU0387 (H773insNPH). To date, 8 platinum-refractory patients with EGFR exon 20 insertion mutation metastatic NSCLC have been enrolled in the clinical trial and treated with poziotinib at a dose of 16 mg PO daily. Two patients have reached the first interval-imaging time point (at 8 weeks of therapy per protocol). Both patients exhibited dramatic partial response, with one patient reporting improvement in dyspnea and cough at one week of therapy. In this early stage of the study, one case of grade 3 paronchycia was observed. One additional platinum- and erlotinib-refractory patient with EGFR exon 20 insertion was treated with poziotinib on compassionate basis. The patient achieved partial response after three weeks of treatment.
Poziotinib has selective activity against EGFR exon 20 mutations and potent activity in cell lines, PDX, and GEM models. Three platinum-refractory patients with EGFR exon 20 mutations have been treated thus far and are evaluable for response; all three had partial responses at the time of the initial scan. Updated data from the ongoing phase 2 clinical trial of poziotinib will be presented at the meeting.
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