Testing for EGFR mutations should be routine in patients with nonâ€“small cell lung cancer. With the presence of an EGFR mutation TKIs are an appropriate treatment option across multiple lines of therapy, according to the latest update from the NCCN.
Rogerio C. Lilenbaum, MD
Testing for EGFR mutations should be routine in patients with non­—small cell lung cancer (NSCLC). With the presence of an EGFR mutation, gefitinib (Iressa), erlotinib (Tarceva), and afatinib (Gilotrif) are appropriate treatment options.
In patients with sensitizing EGFR mutation­—positive NSCLC who progress on a first- or second-generation tyrosine kinase inhibitor (TKI), the type of progression determines the treatment option.
These were the take-home messages delivered at the 2016 NCCN Annual Conference.1
Rogerio Lilenbaum, MD, chief medical officer of Smilow Cancer Hospital at Yale-New Haven, discussed first-line management of EGFR-mutated NSCLC, noting that survival is superior for patients with lung adenocarcinoma who receive appropriate therapy for their molecular alteration compared with patients who have wild-type lung cancer or who have molecular alterations but do not receive appropriate treatment.
“EGFR testing should not be limited to patients who have a high probability of having an EGFR mutation. EGFR testing should be done for every patient with a nonsquamous histology,” Lilenbaum said. “It’s important that clinical enrichment is no longer a criterion to guide molecular testing. It should be routine in clinical practice.”
Version 4.2016 of the NCCN NSCLC guideline recommends EGFR testing with or without ALK testing as part of broad molecular profiling. Without information about EGFR testing, treatment should not be initiated with a TKI, Lilenbaum advised. “If you need to treat someone quickly…even if you anticipate a high probability of EGFR mutation, use chemotherapy first, and switch to a TKI when the information comes back.”
Randomized trials in which patients were selected for the presence of EGFR mutation show a consistent advantage to an EGFR TKI as first-line treatment compared with chemotherapy on the endpoints of overall response rate (ORR) and progression-free survival (PFS). Crossover to TKI in these trials compromised the ability to detect an advantage on overall survival (OS), he said. The agents utilized in this setting were erlotinib, afatinib, and gefitinib. Afatinib has demonstrated an OS benefit in patients with del19 mutations.
In a comparison between TKIs as first-line treatment in the LUX-Lung 7 trial, afatinib showed superior rates of ORR, PFS, and time to failure compared with gefitinib.2
In a phase II study (Lancet Oncol. 2014;15:1236-1244) the combination of bevacizumab (Avastin) and erlotinib was associated with significant prolongation of PFS compared with erlotinib alone (16 vs. 9.7 months; HR, 0.54; P = .0015) in patients with activating EGFR mutations (exon19 del, exon21 L858R).
When treated with EGFR TKIs, 70% of patients with activating mutations will have tumor regression, but eventually disease progresses in most patients, at which time they have developed acquired resistance to gefitinib, erlotinib, or afatinib.
The T790M mutation is the common mechanism of acquired resistance to EGFR TKIs. The type of progression drives second-line treatment, said Leora Horn, MD, MSc, clinical director, Thoracic Oncology Research Program, Vanderbilt Ingram Cancer Center.
Patients with systemic disease progression have multiple new lesions and multiple sites of disease. “Those are the patients you definitely want to switch therapy,” she said, whereas for patients with oligoprogression, maintaining their TKI is reasonable.
Some patients progress only in the CNS while their systemic disease remains stable. “At this time, we often will radiate the lesions in the CNS…and continue the patient on their TKI,” although switching to third- or fourth-generation TKIs may eventually prove more effective,” she said.
In the phase 2 ASPIRATION trial, continuing first-line erlotinib in patients with sensitizing EGFR mutation­—positive NSCLC after progression extended PFS by 3 months compared with discontinuation of erlotinib.3 Adding chemotherapy to gefitinib beyond progression failed to improve PFS or OS in the phase II IMPRESS trial.4
All patients should have a biopsy to evaluate for T790M prior to switching systemic therapy, advised Horn. In patients in whom a tissue biopsy is not possible, a serum-based test for T790M is reasonable.
Osimertinib (Tagrisso) is a third-generation TKI that is approved for the treatment of patients with EGFR mutation—positive NSCLC treated with a first- or second-generation TKI and who develop a T790M mutation as their method of acquired resistance.
FDA approval of osimertinib was based on the phase II AURA 2 trial5 and the AURA extension cohort,6 in which median PFS was 9.7 months following a switch to osimertinib in patients who progressed despite 2 lines of prior therapy with at least one being a TKI.
Version 4.2016 of the guideline for management of NSCLC recommends osimertinib or continuation of erlotinib, afatanib, or gefitinib as subsequent therapy upon progression in asymptomatic patients with a sensitizing EGFR mutation. For symptomatic patients, the guideline calls for subsequent therapy based on the site of progression.