<b>Methods:</b> Patients with advanced NSCLC, known <i>EGFR</i> mutation and progressive disease on an EGFR TKI immediately prior to enrollment without intervening therapy were enrolled.
EGFR mutations (seen in 15 of 89 patients) were also statistically significantly related to response and time to progression, but the association with survival was not statistically significant, and 40% of the patients with mutation had progressive disease.
EGFR mutation was observed in 10 of 27 and significantly more frequently observed in the posttreatment samples from patients with a partial response or stable disease than in those from patients with progressive disease (p = 0.006).
EGFRT790M was identified from plasma DNA in 54% (15 of 28) of patients with prior clinical response to gefitinib/erlotinib, 29% (4 of 14) with prior stable disease, and in 0% (0 of 12) that had primary progressive disease or were untreated with gefitinib/erlotinib.
A 61-year-old woman with EGFR mutation positive stage IV lung adenocarcinoma was administered 1<sup>st</sup> generation EGFR-TKI for 8 months as the first line therapy, then chemotherapy and 2<sup>nd</sup> generation EGFR-TKI after progressive disease (PD).
Actionable EGFR mutations were detected in 24 tissue and 19 ctDNA samples, yielding concordance of 79%, with a shorter time interval between tissue and blood collection associated with increased concordance (P = 0.038). ctDNA sequencing identified eight patients harboring a resistance mutation who developed progressive disease while on targeted therapy, and for whom tissue sequencing was not possible.
Adult patients (age > or = 18 years), with non squamous EGFR mutation, treated with first line palliative therapy, with non progressive disease post 4-6 cycles of pemetrexed-carboplatin were randomized.
Among 26 patients who had received EGFR-TKIs, the mean EGFR mutation content was higher in patients showing partial response (86.1%) or stable disease (48.7%) compared with patients experiencing progressive disease (6.0%) (P = 0.001).
Among the 35 patients who were plasma EGFR mutation positive and treated with first generation of EGFR-tyrosine kinase inhibitors (TKIs), 23 (65.7%) achieved partial response, 11 (31.4%) sustained disease, and 1 (2.9%) progressive disease.
Awareness of this phenomenon with epidermal growth factor receptor tyrosine kinase inhibitors is important for physicians treating patients with NSCLC, so that it is not misinterpreted as progressive disease resulting in premature cessation of effective therapy.
Blood samples were collected at baseline and every treatment cycle and analyzed for 31 RAS, RAF, and EGFR mutations until progressive disease or censoring using droplet digital PCR.
Continuation of EGFR TKI beyond progressive disease is confined to patients in asymptomatic stage when the EGFR addiction is still preserved in some subclones.
Direct sequencing revealed wild-type EGFR, whereas PNA clamping revealed mutant EGFR, in one of five patients who exhibited progressive disease in response to EGFR tyrosine kinase inhibitor; the cell block of this patient contained a high proportion of tumor cells.
Eight patients received an EGFR TKI: three cases with G719X plus another mutation had partial responses (PRs) to erlotinib; of three cases with L858R plus another mutation, two displayed PRs and one (with EGFR-L858R+A871G) progressive disease (PD) to erlotinib; one NSCLC with EGFR-L861Q+E709A and one with delL747_T751+R776S had PRs to EGFR TKIs.
Five of the 13 patients with <i>EGFR</i> mutations were treated with EGFR-TKIs, two of whom manifested a partial response, two stable disease, and one progressive disease.
He developed progressive disease in liver 4 months later, and the biopsy of liver metastases showed neuroendocrine carcinoma maintained the same EGFR mutation.
Here, we conducted a retrospective study to assess 375 patients whose initial biopsy indicated a TKI-sensitizing mutation (either EGFR 19del or L858R) and who developed PD after treatment with first-generation TKIs, and assayed for T790M status.
Heterogeneous responses were seen in patients with progressive disease as best response with a marked size decrease of the biopsied (cMET amplification positive) lesion and progression of other lesions. cMET amplification was not always mutually exclusive with other EGFR TKI resistance mechanisms.