Co-mutational assessment of circulating tumour DNA (ctDNA) during osimertinib treatment for T790M mutant lung cancer

Liquid biopsy for the management of NSCLC patients under osimertinib treatment

Therapeutic management of NSCLC patients is quite challenging as they are mainly diagnosed at a late stage of disease, and they present a high heterogeneous molecular profile. Osimertinib changed the paradigm shift in treatment of EGFR mutant NSCLC patients achieving significantly better clinical outcomes. To date, osimertinib is successfully administered not only as first- or second-line treatment, but also as adjuvant treatment while its efficacy is currently investigated during neoadjuvant treatment or in stage III, unresectable EGFR mutant NSCLC patients. However, resistance to osimertinib may occur due to clonal evolution, under the pressure of the targeted therapy. The utilization of liquid biopsy as a minimally invasive tool provides insight into molecular heterogeneity of tumor clonal evolution and potent resistance mechanisms which may help to develop more suitable therapeutic approaches. Longitudinal monitoring of NSCLC patients through ctDNA or CTC analysis could reveal valuable information about clinical outcomes during osimertinib treatment. Therefore, several guidelines suggest that liquid biopsy in addition to tissue biopsy should be considered as a standard of care in the advanced NSCLC setting. This practice could significantly increase the number of NSCLC patients that will eventually benefit from targeted therapies, such as EGFR TKIs.

Meta-analysis of the prognostic impact of TP53 co-mutations in EGFR-mutant advanced non-small-cell lung cancer treated with tyrosine kinase inhibitors

PURPOSE

To assess the prognostic impact of TP53 mutations in EGFR-mutant advanced NSCLC patients treated with TKIs.

METHODS

Studies exploring the clinical outcomes of EGFR mutant/TP53 wild-type versus EGFR/TP53 co-mutant patients treated with TKIs were selected. Data were cumulated by adopting a fixed and random-effect model.

RESULTS

Overall, 29 trials were eligible. The PFS analysis showed that TP53 co-mutant group has shorter PFS versus EGFR mutant/TP53 wild-type group (HR = 1.67, 95% CI 1.51-1.83, heterogeneity I² =20%, p = 0.18). Patients affected by EGFR/TP53 co-mutant NSCLC have a higher chance of shorter OS versus EGFR mutant/TP53 wild type (HR= 1.89, 95% CI 1.67-2.14, heterogeneity I² = 21%; p = 0.19). The subgroup analysis showed no significant difference between first-second versus third-generation TKIs in both PFS and OS (p = 0.31, p = 0.08).

CONCLUSIONS

TP53 mutations represent a clinically relevant mechanism of resistance to EGFR-TKIs, regardless of their generation. A personalized therapeutical approach should be explored in dedicated clinical trials.

Heterogeneity among tumors with acquired resistance to EGFR tyrosine kinase inhibitors harboring EGFR ‐T790M mutation in non‐small cell lung cancer cells

EGFR‐T790M mutation is a major mechanism underlying acquired resistance to first‐ and second‐generation EGFR tyrosine kinase inhibitors (EGFR‐TKIs) in lung cancer with mutated EGFR. However, differences in the biological characteristics of T790M tumors based on treatment regimens with each generation of EGFR‐TKI are not fully understood. We established cell lines with acquired resistance harboring EGFR‐T790M mutation derived from xenograft tumors treated with each generation of EGFR‐TKI and examined their biological characteristics with respect to third‐generation EGFR‐TKI osimertinib sensitivity. Second‐generation EGFR‐TKI dacomitinib‐resistant cells with T790M‐exhibited higher sensitivity to osimertinib than first‐generation EGFR‐TKI gefitinib‐resistant cells with T790M via inhibition of AKT and ERK signaling and promotion of apoptosis. Furthermore, gefitinib‐resistant cells showed enhanced intratumor heterogeneity accompanied by genomic instability and activation of alternative resistance mechanisms compared with dacomitinib‐resistant cells; this suggests that the maintenance of EGFR dependency after acquiring resistance might depend on the type of EGFR‐TKI. Our results demonstrate that the progression of tumor heterogeneity via both genetic and non‐genetic mechanisms might affect osimertinib sensitivity in tumors with acquired resistance harboring EGFR‐T790M mutation.

A comprehensive prognostic analysis of osimertinib treatment in advanced non-small cell lung cancer patients with acquired EGFR-T790M mutation: a real-world study

PURPOSE

Osimertinib is the standard treatment for advanced non-small cell lung cancer (NSCLC) patients with T790M mutation after the failure of first-/second-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI). We comprehensively analyzed factors that affect the therapeutic efficacy of the osimertinib treatment in NSCLC patients.

METHODS

351 NSCLC patients with T790M mutation receiving osimertinib treatment were included. We investigated the value of different factors in predicting the clinical outcomes of the osimertinib therapy, including progression-free survival (PFS), overall survival (OS) and objective response rate (ORR). Logistic and COX regression were used to identify prognosticators.

RESULTS

In osimertinib therapy, EGFR mutation status (19Del/L858R) at initial diagnosis and the therapeutic choice of prior EGFR-TKI agent was not associated with patients' prognosis. Notably, the PFS of the prior EGFR-TKI was independently related to ORR (OR, 95% CI 0.98, 0.96-1.00, p = 0.030), PFS (HR, 95% CI 0.98, 0.97-1.00, p = 0.009) and OS (HR, 95% CI 0.96, 0.93-0.98, p < 0.001) of osimertinib treatment. Among distinct organ metastases, only bone metastasis was related to the efficacy of osimertinib, in terms of ORR (OR, 95% CI 1.97, 1.27-3.06, p = 0.002), PFS (HR, 95% CI 1.55, 1.18-2.03, p = 0.001) and OS (HR, 95% CI 1.81, 1.27-2.59, p = 0.001). However, the therapeutic efficacy of osimertinib was not further impacted by the accumulation of metastatic organs. A performance status score of 2-4 was also an adverse prognosticator for the osimertinib therapy.

CONCLUSION

PFS of the prior EGFR-TKI treatment, performance status score and bone metastasis were independent prognosticators of the osimertinib treatment. These findings may facilitate clinicians in the decision-making of osimertinib.

The genomic architectures of tumour-adjacent tissues, plasma and saliva reveal evolutionary underpinnings of relapse in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is characterised by a dismal prognosis; nonetheless, limited studies have unveiled the mechanisms underlying HNSCC relapse.

METHODS

Next-generation sequencing was performed to identify the somatic mutations in 188 matched samples, including primary tumours, tumour-adjacent tissues (TATs), pre- and post-operative plasma, saliva and peripheral blood lymphocytes (PBLs) from 27 patients. The evolutionary relationship between TATs and tumours were analysed. The dynamic changes of tumour- and TAT-specific mutations in liquid biopsies were monitored together with survival analysis.

RESULTS

Alterations were detected in 27 out of 27 and 19 out of 26 tumours and TATs, respectively. TP53 was the most prevalently mutated gene in TATs. Some TATs shared mutations with primary tumours, while some other TATs were evolutionarily unrelated to tumours. Notably, TP53 mutations in TATs are stringently associated with premalignant transformation and are indicative of worse survival (hazard ratio = 14.01). TAT-specific mutations were also detected in pre- and/or post-operative liquid biopsies and were indicative of disease relapse.

CONCLUSIONS

TATs might undergo the processes of premalignant transformation, tumorigenesis and eventually relapse by either inheriting tumorigenic mutations from ancestral clones where the tumour originated or gaining private mutations independent of primary tumours. Detection of tumour- and/or TAT-specific genetic alterations in post-operative biopsies shows profound potential in prognostic use.

An adaptive, biomarker-directed platform study of durvalumab in combination with targeted therapies in advanced urothelial cancer

Durvalumab is a programmed death-ligand 1 (PD-L1) inhibitor with clinical activity in advanced urothelial cancer (AUC)¹. AUC is characterized by several recurrent targetable genomic alterations^2-5. This study ( NCT02546661 , BISCAY) combined durvalumab with relevant targeted therapies in biomarker-selected chemotherapy-refractory AUC populations including: (1) fibroblast growth factor receptor (FGFR) inhibitors in tumors with FGFR DNA alterations (FGFRm); (2) pharmacological inhibitor of the enzyme poly-ADP ribose polymerase (PARP) in tumors with and without DNA homologous recombination repair deficiency (HRRm); and (3) TORC1/2 inhibitors in tumors with DNA alteration to the mTOR/PI3K pathway^3-5.This trial adopted a new, biomarker-driven, multiarm adaptive design. Safety, efficacy and relevant biomarkers were evaluated. Overall, 391 patients were screened of whom 135 were allocated to one of six study arms. Response rates (RRs) ranged 9-36% across the study arms, which did not meet efficacy criteria for further development. Overall survival (OS) and progression-free survival (PFS) were similar in the combination arms and durvalumab monotherapy arm. Biomarker analysis showed a correlation between circulating plasma-based DNA (ctDNA) and tissue for FGFRm. Sequential circulating tumor DNA analysis showed that changes to FGFRm correlated with clinical outcome. Our data support the clinical activity of FGFR inhibition and durvalumab monotherapy but do not show increased activity for any of the combinations. These findings question the targeted/immune therapy approach in AUC.

Complex EGFR mutations with secondary T790M mutation confer shorter osimertinib progression-free survival and overall survival in advanced non-small cell lung cancer

OBJECTIVES

Osimertinib is active against epidermal growth factor receptor (EGFR) T790M-mutated non-small cell lung cancer (NSCLC). However, its efficacy against complex EGFR mutations with T790M has not been evaluated.

MATERIALS AND METHODS

In order to detect complex EGFR mutations, we consecutively sequenced cancer tissues by RNA reverse transcription polymerase chain reaction. Patients with advanced NSCLC with activating EGFR mutation and secondary T790M who received osimertinib were enrolled. Patients' clinicopathologic characteristics, prior treatment details, and osimertinib treatment outcomes were analyzed.

RESULTS

Totally, 165 sequenced patients were analyzed. Eleven (7%) of them had complex EGFR mutations with T790M. The osimertinib response rate was 27%. They had a shorter progression-free survival (PFS) (median, 2.9 and 9.7 months, p < 0.001) and overall survival (OS) (median, 17.8 and 31.0 months, p = 0.01) than patients with a single EGFR mutation with T790M. After osimertinib failure, seven patients received rebiopsy with molecular analysis. Four lost the T790M, two transformed to small cell and one acquired C797S. Moreover, taking the median as the demarcation, patients received shorter prior EGFR tyrosine kinase inhibitor (TKI) treatment duration had a shorter osimertinib PFS (median, 7.3 and 13.8 months, p < 0.001) and OS (median, 21.5 and 36.7 months, p = 0.003). Multivariate Cox regression analysis confirmed complex EGFR mutations and prior EGFR TKI treatment duration were independent factors for osimertinib PFS and OS.

CONCLUSIONS

Complex EGFR mutations and shorter prior EGFR TKI treatment duration may confer shorter osimertinib PFS and OS in advanced NSCLC with secondary T790M mutation.

The Status of the EGFR T790M Mutation is associated with the Clinical Benefits of Osimertinib Treatment in Non-small Cell Lung Cancer Patients: A Meta-Analysis

Background and Purpose: Pervious studies have demonstrated that the loss of EGFR T790M after Osimertinib treatment may be the cause of Osimertinib resistance. Here, we conducted a meta-analysis to evaluate the association between the persistence of EGFR T790M and the clinical benefits of Osimertinib in non-small cell lung cancer (NSCLC) patients with baseline EGFR T790M mutation.

Experimental design and Methods: PUBMED, EMBASE, and Cochrane databases were searched for eligible studies that provided the survival outcomes including overall survival (OS), progression-free survival (PFS) or time to discontinuation (TTD) data for each patient treated with Osimertinib with the status of the T790M mutation tested after Osimertinib resistance. The hazard ratios (HRs) and their 95% confidence intervals (CI) were calculated for each study.

Results: In total, eight eligible studies were included in the analysis, among which six studies provided the data on PFS, and the other two studies provided the TTD data. Overall, 312 patients (151 patients with the persistence of T790M) were identified. The persistence of T790M was associated with longer PFS (HR, 0.40; 95% CI, 0.19-0.84; P=0.01) and TTD (HR, 0.54; 95% CI, 0.39-0.76; P=0.0004). Furthermore, overall analysis the survival outcomes including PFS and TTD subgroups also showed preferable clinical benefits for patients with the T790M persistence (HR, 0.57; 95%CI, 0.45-0.73; P<0.00001).

Conclusions: Our findings confirm the persistence of T790M is associated with the clinical benefits of Osimertinib in NSCLC patients with baseline EGFR T790M mutation treated with Osimertinib.

Co-mutational assessment of circulating tumour DNA (ctDNA) during osimertinib treatment for T790M mutant lung cancer

Osimertinib is designed to target the secondary resistant EGFR T790M mutant and has shown outstanding clinical efficacy. However, the prognostic prediction of osimertinib patients is a big problem in clinical practice. The resistance mechanism of osimertinib is also not fully understood. NGS and a 1021 gene capture panel were used to analyse the somatic mutation profile of thirty‐six lung adenocarcinoma patients' serial ctDNA samples. Progression‐free survival of subgroup patients is analysed. Patients harbour TP53 mutations and patients with higher TMB value in pre‐treatment samples showed a shorter PFS. Moreover, compared to CT evaluation, ctDNA changes generally correlated with treatment responses in most patients. Novel resistance mechanisms are discovered including EGFR mutations and alternative activation pathway. Our results implied a broad potential of ctDNA as an adjuvant tool in practical clinical management of NSCLC patients. ctDNA could help with clinical practice during osimertinib treatment, regarding monitoring tumour response, detecting development of heterogeneity, identifying potential resistance mechanisms, predicting treatment efficacy and patient outcome.