1534P - TP53 mutations predicts worse prognosis in EGFR-mutated NSCLC patients receiving TKIs in first- or further line of treatment

Abstract

BackgroundNon-small cell lung cancer (NSCLC) patients carrying epidermal growth factor receptor (EGFR) mutations are sensitive to tyrosine kinase inhibitors (TKIs); nonetheless, about 20% of patients show primary resistance to TKIs. We previously demonstrated the association between TP53 mutations and primary resistance to first-line TKIs in EGFR-mutated adenocarcinoma (ADC) patients. Here we analyze a validation case series of ADC patients treated with first-line TKIs to confirm our previous data, and we assess the association between TP53 status and the prognosis of ADC patients treated with third generation TKIs. MethodsWe considered 136 ADC EGFR-mutated patients treated with a TKI in the first-line setting. Also, we analyzed 42 patients who developed T790M mutation and were treated with a third generation TKI in second- or further line setting. EGFR and TP53 mutation analyses were performed by Sanger Sequencing or Next Generation Sequencing methodologies. TP53 mutations were evaluated in relation to disease control rate (DCR: complete response [CR], partial response [PR] or stable disease [SD]), objective response rate (ORR: CR, PR), progression-free survival (PFS) and overall survival (OS). ResultsOf 136 patients, we found 42 (31%) TP53 mutations: 12 mutations in exon 5 (28.6%), 6 in exon 6 (14.3%), 13 in exon 7 (30.9%), and 11 in exon 8 (26.2%). DCR and ORR were 31.8% and 32.5% in TP3-mutated patients with respect to 68.6% and 67.4% in TP53 wild-type (wt) patients, respectively. Exon 8 TP53-mutated patients had a worse PFS with respect to TP53wt patients (HR 3.19 [1.62-6.27], p=0.001), but not OS. Moreover, we assessed TP53 status in 42 patients who developed a T790M mutation and received a third generation TKI in second or additional lines of treatment. In 30 patients with evaluable clinical response, DCR and ORR were 62.5% and 25% in TP53 mutated patients, with respect to 77.2% and 54.5% in the TP53wt patients, respectively. Data analyses of PFS and OS are ongoing. ConclusionsEGFR-mutated NSCLC patients with concomitant TP53 mutations had a worse clinical response to first-, second-, and third generation TKIs, administrated in any line of treatment. Legal entity responsible for the studyIstituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.