Evolution and Clinical Impact of EGFR Mutations in Circulating Free DNA in the BELIEF Trial

Adaptive therapy to circumvent drug resistance to tyrosine kinase inhibitors in cancer: is it clinically relevant?

INTRODUCTION

Cancer is highly adaptable and is constantly evolving against current targeted therapies such as tyrosine kinase inhibitors. Despite advances in recent decades, the emergence of drug resistance to tyrosine kinase inhibitors constantly hampers therapeutic efficacy of cancer treatment. Continuous therapy versus intermittent clinical regimen has been a debate in drug administration of cancer patients. An ecologically-inspired shift in cancer treatment known as 'adaptive therapy' intends to improve the drug administration of drugs to cancer patients that can delay emergence of drug resistance.

AREAS COVERED

We discuss improved understanding of the concept of drug resistance, the basis of continuous therapy, intermittent clinical regimens, and adaptive therapy will be reviewed. In addition, we discuss how adaptive therapy provides guidance for future cancer treatment.

EXPERT OPINION

The current understanding of drug resistance in cancer leads to poor prognosis and limited treatment options in patients. Fighting drug resistance mutants is constantly followed by new forms of resistance. In most reported cases, continuous therapy leads to drug resistance and an intermittent clinical regimen vaguely delays it. However, adaptive therapy, conceptually, exploits multiple parameters that can suppress the growth of drug resistance and provides safe treatment for cancer patients in the future.

Changes in the concentration of EGFR-mutated plasma DNA in the first hours of targeted therapy allow the prediction of tumor response in patients with EGFR-driven lung cancer

PURPOSE

This study aimed to analyze changes in the plasma concentration of EGFR-mutated circulating tumor DNA (ctDNA) occurring immediately after the start of therapy with EGFR tyrosine kinase inhibitors (TKIs).

METHODS

Serial plasma samples were collected from 30 patients with EGFR-driven non-small cell lung cancer before intake of the first tablet and at 0.5, 1, 2, 3, 6, 12, 24, 36 and 48 h after the start of the therapy. The content of EGFR alleles (exon 19 deletions or L858R) in ctDNA was measured by ddPCR.

RESULTS

ctDNA was detected at base-line in 25/30 (83%) subjects. Twelve (50%) out of 24 informative patients showed > 25% reduction of the ctDNA content at 48 h time point; all these patients demonstrated disease control after 4 and 8-12 weeks of therapy. The remaining 12 individuals showed either stable content of EGFR-mutated ctDNA (n = 5) or the elevation of ctDNA concentration (n = 7). 10 of 12 patients with elevated or stable ctDNA level achieved an objective response at 4 weeks, but only 5 of 10 evaluable patients still demonstrated disease control at 8-12 weeks (p = 0.032, when compared to the group with ctDNA decrease). The decline of the amount of circulating EGFR mutant copies at 48 h also correlated with longer progression-free survival (14.7 months vs. 8.5 months, p = 0.013).

CONCLUSION

Comparison of concentration of EGFR-mutated ctDNA at base-line and at 48 h after the start of therapy is predictive for the duration of TKI efficacy.

The EPICAL trial, a phase Ib study combining first line afatinib with anti-EGF vaccination in EGFR-mutant metastatic NSCLC

INTRODUCTION

Combination of anti-EGFR monoclonal antibodies or immune checkpoint inhibitors with TKIs has shown minimal benefit in EGFR mutant (EGFR-mut) NSCLC patients. Consequently, new combination approaches are needed.

PATIENTS AND METHODS

The EPICAL was a single arm, phase 1b study to evaluate safety, tolerability and anti-tumor activity of first line afatinib combined with anti-EGF vaccination in advanced EGFR-mut patients. EGFR status and mutations in liquid biopsies were determined by reverse transcriptase-polymerase chain reaction; serum biomarkers by ELISA and Western blotting analysis.

RESULTS

The assay enrolled 23 patients, 21 completed the anti-EGF immunization phase. Treatment was well tolerated and no serious adverse events (SAEs) related to the anti-EGF vaccine were reported. Objective response and disease control rates were 78.3% (95%CI = 53.6-92.5) and 95.7% (95%CI = 78.1-99.9), respectively. After a median follow-up of 24.2 months, median progression-free survival (PFS) was 14.8 months (95% CI = 9.5-20.1) and median overall survival (OS) 26.9 months (95% CI = 23.0-30.8). Among the 21 patients completing the immunization phase, PFS was 17.5 months (95% CI = 12.0-23.0) and OS 26.9 months (95% CI = 24.6-NR). At the end of the immunization phase, all 21 patients showed high serum titers of anti-EGF antibodies, while EGF levels had decreased significantly. Finally, treatment with fully immunized patient's sera inhibited the EGFR pathway in tumor cells growing in vitro.

CONCLUSIONS

Combination treatment with an anti-EGF vaccine is well tolerated; induces a sustained immunogenic effect and might enhance the clinical efficacy of EGFR TKIs.

First-line osimertinib in patients with epidermal growth factor receptor-mutant non-small-cell lung cancer and with a coexisting low allelic fraction of Thr790Met

AIM OF THE STUDY

The AZENT (NCT02841579) study aimed to assess the efficacy and safety of first-line osimertinib in patients with epidermal growth factor receptor(EGFR)mutation-positive advanced non-small-cell lung cancer (NSCLC) and with a coexisting low allelic fraction of Thr790Met.

METHODS

In this multicentre, single-arm, open-label, phase IIa study, patients with locally advanced or metastatic NSCLC harbouring centrally confirmedEGFR Thr790Met mutation received 80 mg osimertinib daily. The primary end-point was objective response rate (ORR). The secondary end-points included disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety. Efficacy was assessed as per Response Evaluation Criteria in Solid Tumours, version 1.1. Blood samples collected at baseline, end of week 2 and disease progression were analysed using next-generation sequencing. As osimertinib was approved as a first-line therapy during the trial, this led to early termination of phase II; thus, analysis is considered exploratory.

RESULTS

Twenty-two patients were enrolled and received osimertinib. All 22 patients were included in the efficacy and safety analysis. At the data cutoff, 10 (50%) patients remained on treatment. The median duration of follow-up was 24.4 months (interquartile range 12.9 to 26.0). The ORR was 77.3% (17/22 [95% confidence interval {CI} 54.6 to 89.3]). The DCR was 86.4% (19/22, [95% CI 65.1 to 97.1]). The median PFS was 23.1 months (95% CI 14.1 to NE). The median OS was 28·4 months (95% CI 25.6 to NE).

CONCLUSION

Despite early study termination, osimertinib first-line therapy yields an overall PFS of 23.1 months in EGFR-mutant patients harbouring a coexisting low allelic fraction of EGFR Thr790Met mutation.

EGFR-plasma mutations in prognosis for non-small cell lung cancer treated with EGFR TKIs: A meta-analysis

BACKGROUND

The plasma-based epidermal growth factor receptor (EGFR) mutation testing is approved recently to use in clinical practice. However, it has not been used as a prognostic marker yet because of contradictory results.

AIM

This meta-analysis aims to clarify the role of the EGFR-plasma test in prognosis for non-small cell lung cancer (NSCLC) who have mutant tumors and receive EGFR tyrosine kinase inhibitors (TKIs).

METHODS AND RESULTS

The PubMed/MEDLINE, Web of Science, Cochrane Library, and Google Scholar databases were searched for relevant studies by April 10, 2021. The hazard ratio (HR) from reports was extracted and used to assess the correlation of EGFR-plasma status with progression-free survival (PFS) and overall survival (OS). A total of 35 eligible studies with 4106 patients were enrolled in the final analysis. Patients with concurrent EGFR mutations in pretreatment plasma have shorter PFS (HR = 2.00, 95% confidence interval [CI]: 1.73-2.31, p < .001) and OS time (HR = 2.31, 95% CI: 1.89-2.83, p < .001) compared to the tumor-only mutation cases. Besides, the persistence of EGFR-activating mutations in post-treatment plasma is associated with worse PFS (HR = 3.84, 95% CI: 2.96-4.99, p < .001) and OS outcome (HR = 3.22, 95% CI: 2.35-4.42, p < .001) compared to others. Notably, the prognostic value of the EGFR-plasma test is also validated in treatment with third-generation EGFR TKI and significance regardless of different detection methods.

CONCLUSION

The presence of EGFR-plasma mutations at pretreatment and after EGFR TKI initiation is the worse prognostic factor for PFS and OS in NSCLC.

First-Line Afatinib plus Cetuximab for EGFR-Mutant Non-Small Cell Lung Cancer: Results from the Randomized Phase II IFCT-1503 ACE-Lung Study

PURPOSE

Double inhibition of epidermal growth factor receptor (EGFR) using a tyrosine kinase inhibitor plus a monoclonal antibody may be a novel treatment strategy for non-small cell lung cancer (NSCLC). We assessed the efficacy and toxicity of afatinib + cetuximab versus afatinib alone in the first-line treatment of advanced EGFR-mutant NSCLC.

PATIENTS AND METHODS

In this phase II, randomized, open-label study, patients with stage III/IV EGFR-positive NSCLC were randomly assigned (1:1) to receive afatinib (group A) or afatinib + cetuximab (group A + C). Oral afatinib 40 mg was given once daily; cetuximab 250 mg/m² was administered intravenously on day 15 of cycle 1, then every 2 weeks at 500 mg/m² for 6 months. The primary endpoint was time to treatment failure (TTF) rate at 9 months. Exploratory analysis of EGFR circulating tumor DNA in plasma was performed.

RESULTS

Between June 2016 and November 2018, 59 patients were included in group A and 58 in group A + C. The study was ended early after a futility analysis was performed. The percentage of patients without treatment failure at 9 months was similar for both groups (59.3% for group A vs. 64.9% for group A + C), and median TTF was 11.1 (95% CI, 8.5-14.1) and 12.9 (9.2-14.5) months, respectively. Other endpoints, including progression-free survival and overall survival, also showed no improvement with the combination versus afatinib alone. There was a slight numerical increase in grade ≥3 adverse events in group A + C. Allele frequency of the EGFR gene mutation in circulating tumor DNA at baseline was associated with shorter PFS, regardless of the treatment received.

CONCLUSIONS

These results suggest that addition of cetuximab to afatinib does not warrant further investigation in treatment-naïve advanced EGFR-mutant NSCLC.

Analysis of circulating tumour DNA to identify patients with epidermal growth factor receptor-positive non-small cell lung cancer who might benefit from sequential tyrosine kinase inhibitor treatment

BACKGROUND

Survival data support the use of first-line osimertinib as the standard of care for epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC). However, it remains unclear whether upfront osimertinib is superior to sequential first- or second-generation tyrosine kinase inhibitors (TKIs) followed by osimertinib for all patients. It is impossible to predict which patients are at high risk of progression, and this constitutes a major limitation of the sequential TKI approach.

PATIENTS AND METHODS

A total of 830 plasma samples from 228 patients with stage IV, EGFR-positive NSCLC who were treated with first-line TKIs were analysed by digital polymerase chain reaction (dPCR).

RESULTS

The circulating tumour DNA (ctDNA) levels helped to identify patients with significantly improved survival rate, regardless of the treatment. Patients treated with first- or second-generation TKIs (N = 189) with EGFR mutations in plasma at a mutant allele frequency (MAF) <7% before treatment initiation (low-risk patients) or who were ctDNA negative after 3 or 6 months of treatment and with an MAF <7% at diagnosis (high responders) had two-thirds lower risk of death than patients in the opposite situation (adjusted hazard ratio [HR] = 0.38; 95% confidence interval [CI]: 0.23-0.64 and HR = 0.22; 95% CI: 0.12-0.42, respectively). The median overall survival (OS) for low-risk patients and high responders treated with first- or second-generation TKIs was 34.2 months and not reached, respectively, regardless of second-line treatment. There were no significant difference in OS between low-risk or high-responder patients treated upfront with osimertinib (N = 39) and those treated under a sequential approach with osimertinib (N = 60). Median OS was not reached in both cases.

CONCLUSIONS

Pre-treatment ctDNA levels identify low-risk patients, who may benefit from sequential TKI treatment. Information regarding EGFR mutation clearance can help to improve patient selection.

Phase II open-label multicenter study to assess the antitumor activity of afatinib in lung cancer patients with activating epidermal growth factor receptor mutation from circulating tumor DNA: Liquid-Lung-A

BACKGROUND

Mutation analysis of circulating tumor DNA (ctDNA) is used for diagnosing lung cancer. This trial aimed to assess the efficacy of afatinib in treatment-naïve patients with lung cancer harboring epidermal growth factor receptor mutations (EGFRm, exon 19 deletions or exon 21 point mutations) detected based on ctDNA.

METHODS

The primary objective was the objective response rate (ORR) in the response evaluable (RE) population. EGFRm analysis of ctDNA was performed using PANA Mutype. Of the 331 patients screened, ctDNA was positive in 21% (68/331) in the detection of activating EGFRm. Among 81 subjects with tumor EGFRm, 48 showed matched EGFRm in their ctDNA (59% sensitivity).

RESULTS

Therapy with afatinib 40 mg was initiated in 21 (female, 17; adenocarcinoma, 20) patients (intention-to-treat, ITT); dose modifications were made in 15 (71%). The ORR was 74% in the RE population (14/19); 11 patients showed EGFRm only in ctDNA (Group A), whereas 10 exhibited the same EGFRm in their ctDNA and tumor DNA (Group B). There was no significant difference in ORR between Groups A and B (80% and 67% RE, respectively). Median progression-free survival (PFS) was 12.0 months, and no significant difference was observed according to the final afatinib dose, type of EGFRm, and Group A versus B. After progression, T790M mutation was found in 40% (6/15) of patients, and osimertinib was used as a second-line treatment.

CONCLUSIONS

Afatinib showed similar ORR and PFS in patients with lung cancer harboring EGFRm in their ctDNA regardless of tumor EGFRm results.

KEY POINTS

SIGNIFICANT FINDINGS OF THE STUDY: Afatinib showed favorable ORR and PFS regardless of the tumor EGFR mutation status results, similar to the findings of previous trials assessing afatinib as first-line treatment of EGFR-mutated non-small cell lung cancer based on tumor genotyping.

WHAT THIS STUDY ADDS

Our findings emphasize that the survival benefit of afatinib treatment can be achieved not only by appropriate dose reduction with frequent and detailed monitoring of toxicities, but also by using noninvasive (ctDNA) assays in a real-world setting.

Phase II clinical trial with metronomic oral vinorelbine and tri-weekly cisplatin as induction therapy, subsequently concomitant with radiotherapy (RT) in patients with locally advanced, unresectable, non-small cell lung cancer (NSCLC). Analysis of survival and value of ctDNA for patient selection

BACKGROUND

Little progress has been achieved in non-small cell lung cancer (NSCLC) patients with unresectable stage III disease and new drug schemes are warranted.

MATERIAL AND METHODS

In this open-label, single-arm, phase II trial 65 treatment-naïve stage III NSCLC deemed surgically unresectable by a multidisciplinary team were treated with 2 cycles of induction cisplatin at 80 mg/m² every 21 days plus metronomic oral vinorelbine at 50 mg/day every Monday, Wednesday and Friday. During the concomitant treatment with thoracic radiotherapy cisplatin was administered in the same manner but oral vinorelbine was reduced to 30 mg/day. The objective was to administer a total radiotherapy dose of 66 Gy in 33 daily fractions of 2 Gy. The primary endpoint was progression-free survival (PFS). Correlation between circulating tumor DNA (ctDNA) levels and survival was also evaluated.

RESULTS

Fifty-five (78.5 %) patients completed treatment. Overall response rate, by RECIST criteria, was 66.2 %. Four (6.2 %) patients had complete response, 39 (60.0 %) partial response and 12 (18.5 %) stable disease. Seven patients (10.8 %) had progressive disease during the induction period. Median follow-up was 29.1 months (m), median PFS was 11.5 m (95 %CI: 9.6-15.4). PFS at 12 m in the intention-to-treat (ITT) population was 47.8 % (95 %CI: 35.1-59.4 %) and median OS was 35.6 m (95 %CI: 24.4-46.8). Grade ≥3 treatment-related adverse events occurred in 14 (21.5 %) patients during induction and in 13 (24.5 %) patients during concomitant treatment with esophagitis occurring in 3% and pneumonitis in 1.5 % of the patients. Patients with undetectable ctDNA after 3 m follow-up had median PFS and OS of 18.1 m (95 %CI: 8.8-NR) and not reached (NR) (95 %CI: 11.3-NR), respectively, compared with 8.0 m (95 %CI: 2.7-NR) and 24.7 m (95 %CI: 5.7-NR) for patients who remained ctDNA positive at that time point.

CONCLUSIONS

Metronomic oral vinorelbine and cisplatin obtains similar efficacy results with significantly lower toxicity than the same chemotherapy at standard doses. ctDNA can identify populations with particularly good prognosis.

A Phase II Trial of Osimertinib as the First-Line Treatment of Non-Small Cell Lung Cancer Harboring Activating EGFR Mutations in Circulating Tumor DNA: LiquidLung-O-Cohort 1

Purpose

Osimertinib is a potent, irreversible third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor for both EGFR-activating and T790M resistant mutation. The treatment efficacy of osimertinib was assessed in previously untreated patients with metastatic non–small cell lung carcinoma (NSCLC) harboring activating EGFR mutations in circulating tumor DNA (ctDNA) as well as tumor DNA.

Materials and Methods

Patients with activating EGFR mutations in their tumor DNA underwent screening with ctDNA analysis using Mutyper and Cobas v2 assays. Enrolled subjects received osimertinib 80 mg, once daily. Primary endpoint was objective response rate (ORR) and secondary endpoints were ctDNA test sensitivity, progression-free survival (PFS), duration of response (DoR), and safety.

Results

Among 39 screened patients, 29 were ctDNA positive for activating EGFR mutations and 19 were enrolled (ex19del, n=11; L858R/L861Q, n=7; G719A, n=1). Median age was 70 and most patients had brain metastases (15/19, 79%). ctDNA test sensitivity for activating EGFR mutations was 74% using both methods and 62% (Mutyper) or 64% (Cobas v2) for individual methods. ORR was 68% (13/19), median PFS was 11.1 months (95% confidence interval [CI], 0.0 to 26.7), and median DoR was 17.6 months (95% CI, 3.5 to 31.7). ORR and median PFS were significantly superior with ex19del (91%; 21.9 months; 95% CI, 5.5 to 38.3) than with L858R/L861Q (43%; 5.1 months; 95% CI, 2.3 to 7.9). One patient discontinued the drug because of drug-related interstitial pneumonitis.

Conclusion

Osimertinib had favorable efficacy in the first-line treatment of metastatic NSCLC harboring activating EGFR mutations in ctDNA as well as tumor DNA.

An Observational Study of Acquired EGFR T790M-Dependent Resistance to EGFR-TKI Treatment in Lung Adenocarcinoma Patients in Taiwan

In Taiwan, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs), gefitinib, erlotinib, and afatinib are served as first-line therapy for non-small lung cell cancer (NSCLC) patients with EGFR sensitizing mutations. However, the majority of patients who initially respond to EGFR-TKIs, progress through acquiring EGFR T790M mutations (T790M), which is the most common resistant mechanism. Patients with T790M gain the opportunity of subsequent treatment with third-generation EGFR-TKI, osimertinib. This study aimed to evaluate the association between prior EGFR-TKI therapy and incidence of acquired T790M resistance in lung adenocarcinoma patients who have progressed on first/second-generation EGFR-TKI therapy. This retrospective study included lung adenocarcinoma patients who had a radiographically-confirmed progressive disease under EGFR-TKI treatment and had re-biopsy samples for T790M testing from seven medical centers in Taiwan from June 2013 to December 2018. Patients harboring de novo T790M or using more than one EGFR-TKI were excluded. Of the 407 patients enrolled, the overall T790M acquisition rate was 52.8%. The patients treated with gefitinib, erlotinib or afatinib had a statistically significant difference in the T790M rates (59.9, 45.5, and 52.7%, respectively; p = 0.037) after disease progression. Patients with common baseline EGFR mutations (Del-19 and L858R) (p = 0.005) and longer treatment duration with EGFR-TKIs (p < 0.001) had higher chances of T790M acquisition. Multivariate logistic regression analysis further showed that patients with common baseline EGFR mutations, gefitinib (compared to erlotinib) administration, and longer treatment duration with EGFR-TKIs had higher T790M incidence. There was no significant difference in the incidence of acquired T790M between different re-biopsy tissue samples or complications. In conclusion, this study showed that patients who progressed from gefitinib treatment, bearing common EGFR mutations, and with longer EGFR-TKI treatment duration had increased incidence of T790M acquisition and, therefore, were suitable for subsequent osimertinib treatment.

Evaluation of plasma EGFR mutation as an early predictor of response of erlotinib plus bevacizumab treatment in the NEJ026 study

Background

The NEJ026 Phase 3 study demonstrated that erlotinib and bevacizumab (BE)-treated NSCLC patients with EGFR mutations had significantly better progression-free survival (PFS) than those treated with erlotinib alone (E). This study included a prospective analysis of the relationship between the mutational status of EGFR in plasma circulating tumor DNA (ctDNA) and the efficacy of TKI monotherapy or combination therapy. We describe these results herein.

Methods

Plasma samples were collected from patients enrolled in NEJ026 at the start of treatment (P0), 6 weeks after the start of treatment (P1), and upon confirmation of progressive disease (P2). Plasma ctDNA was analyzed using a modified PNA-LNA PCR clamp method. PFS and OS according to EGFR status at the time of plasma collection were evaluated.

Findings

Plasma activating EGFR mutation (aEGFR) at P0 was detected in 68% of cases; patients without plasma aEGFR had longer PFS. The frequency of T790M mutation at P2 was similar in both arms: 8 (19.0%) in BE and 11 (20.8%) in E. Based on the aEGFR profiles, PFS was evaluated among three groups: type A [P0(-), P1(-)], type B [P0(+), P1(-)], and type C [P0(+), P1(+)]. This revealed that BE was more efficacious than E, and that BE was associated with improved PFS in all types.

Interpretation

Pre-treatment plasma aEGFR status have a potential of early predictor of response of TKI efficacy. Monitoring plasma aEGFR mutation will contribute to selection and continuation of treatment with BE or E.

Funding

Chugai Pharmaceutical.