Combination of tissue and liquid biopsy molecular profiling to detect transformation to small cell lung carcinoma during osimertinib treatment

Abstract

Background: Histological transformation of advanced non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is one of the mechanisms of resistance to third-generation tyrosine kinase inhibitors (TKIs), such as osimertinib. This acquired TKI resistance is linked to the high degree of tumor heterogeneity and adaptive cellular signaling pathways, including epidermal growth factor receptor ( EGFR)-dependent pathways, observed in NSCLC. Methods: Here, we investigated a series of paired pre- and post-histological transformation biopsies obtained from three patients initially having a NSCLC with an EGFRactivating mutation treated with first-generation TKI, who then received osimertinib as second-line after EGFRT790M resistance and, lastly, developed a histological transformation to SCLC. Both tissue and liquid biopsies were analyzed using large panel sequencing approaches at various time points to reconstruct the clonal evolutionary history of the tumor. Results: Our complementary analysis of tumor tissue and circulating tumor DNA samples allowed us to better characterize the histological and molecular alterations associated with resistance to osimertinib. SCLC transformation was linked to the presence of several concomitant gene alterations, including EGFR, TP53 and RB1, but also to specific signal bypass, such as EGFR and MET amplifications and activation of the PI3K/AKT/mTOR pathway. Conclusion: Our report emphasizes the mutational landscape of SCLC histological transformation and highlights the importance of combining tissue and liquid biopsy profiling before and during osimertinib treatment to predict such histological transformation.

Liquid Biopsy for Small Cell Lung Cancer either De Novo or Transformed: Systematic Review of Different Applications and Meta-Analysis

“…Vendrell 2020 [71] ddPCR and NGS In 2 patients, elevation of AF in ctDNA of EGFRdel19 (from 6% to 17%) and TP53 M246K (from 6% to 24%), and of EGFRL858R (from 4% to 6%) and TP53…”

“…Our group and others described cases of patients with progressive NSCLC under TKI treatment with evidence of sharp elevation of AF of EGFR activating mutation in ctDNA measured with ddPCR, concurrent with evidence of histologic transformation to SCLC [ 64 , 65 , 66 ]. Performing NGS on ctDNA, other researchers also reported a significant elevation in EGFR mutation AF concomitant with the increase in AF of TP53 , RB1 , or PIK3CA alterations before or at the moment of the histologic transformation, after TKI failure [ 67 , 68 , 69 , 70 , 71 ]. A subsequent reduction in the allelic abundance of these mutations after an SCLC-directed treatment has been reported, as well [ 69 , 70 ].…”

“…Patients with stable or increasing EGFR mutant AF at PD showed worse PFS and OS [ 96 ]. Interestingly, increasing levels of EGFR activating mutation in ctDNA were described in all the case reports (8 patients overall) available in literature in which LB was performed after TKI failure with evidence of small cell transformation [ 64 , 65 , 66 , 67 , 69 , 71 ]. In two other cases, the EGFR activating mutation was not retained in neuroendocrine cells, or ctDNA analysis was performed after chemotherapies with platinum and docetaxel, and the EGFR mutant AF was not elevated [ 70 ].…”

“…Time not in scale. Red: Schmid 2020 [ 69 ]; dark blue: Pizzutilo 2019 [ 64 ]; yellow and black: 2 patients by Minari 2018 [ 66 ]; green: Iijima 2018 [ 67 ]; orange: 1 patient by Tsui 2018, the other 2 patients were not reported because the diagnosis of histologic transformation was performed under chemotherapy potentially active against SCLC [ 70 ]; light blue: Mooradian 2017 [ 68 ]; purple: 2 patients by Vendrell 2020; a third patient was not represented because AF at the moment of transformation was not reported [ 71 ]. The yellow background represents the EGFR mutated NSCLC; the pink background represents the histologic transformation.…”

EGFR-dependent mechanisms of resistance to osimertinib determined by ctDNA NGS analysis identify patients with better outcome

“…BRAF V600E was observed in one case. Our team recently reported that one patient harboring this alteration benefited from sequential treatment with dabrafetinib/trametinib and osimertinib (38). Two patients with a MET amplification were also identified by ctDNA NGS and could have benefited from a combination of crizotinib and osimertinib to overcome acquired resistance (39).…”