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P1.01 - Poster Session/ Treatment of Advanced Diseases – NSCLC (ID 206)
- Event: WCLC 2015
- Type: Poster
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
P1.01-017 - Two Cases of NSCLC with EGFR Exon 20 Insertions with Major Clinical Response to Cetuximab-Containing Therapies (ID 653)
09:30 - 17:00 | Author(s): R.J. Hoyer
Lung tumors with EGFR Exon 20 mutations, particularly insertions between the amino acids Y764 and V774, present a major challenge for treatment. These mutations are known to confer resistance to current EGFR specific tyrosine kinase inhibitors (TKI). The mechanism of this resistance is described by Yasuda et al. as a “wedge” formed by the aberrant amino acids locking the C-helix in an inward, active position. This structural aberration prevents the TKI from accessing the critical pocket within the protein and inhibiting kinase activity. Without the ability to treat these tumors with TKIs, alternate treatments need to be pursued.
We present, as index cases, two patients with metastatic lung adenocarcinomas demonstrating TKI unresponsive insertions in exon 20. Both patients had exuberant clinical and radiographic responses to cetuximab, an EGFR specific monoclonal antibody.
The first patient is a 39 year old male never-smoker with lung adenocarcinoma. The disease had progressed prior to molecular identification of the EGFR mutation, and the patient developed bilateral lung disease and metastatic lymph node and brain lesions. An exon 20 EGFR mutation (p.N771_P772insPHGH c.2313_2314insCCCCACGGGCAC) was identified. Following 4th line therapy with combination chemiotherapy plus cetuximab, the tumor burden was dramatically decreased and the patient had markedly improved functional status with the ability to return to employment. The second patient is a 71 year old male never-smoker with lung adenocarcinoma. The disease progressed and the patient developed widely metastatic disease. An exon 20 EGFR mutation (P770_N771insNPP) was identified. The patient was treated with combination cetuximab and afatinib therapy and experienced a dramatic decrease in lung and metastatic tumor burden with improved functional status.
Cetuximab-containing therapeutic regimens may be a viable therapy for what previously have been considered treatment resistant molecular insults. Additional cases of these mutations and treatment with cetuximab are needed to demonstrate that these results are reproducible and that they warrant study in prospective clinical trials.
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