Mechanisms of acquired resistance to afatinib clarified with liquid biopsy

The Evolving Paradigm of Antibody-Drug Conjugates Targeting the ErbB/HER Family of Receptor Tyrosine Kinases

Current therapies targeting the human epidermal growth factor receptor (HER) family, including monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs), are limited by drug resistance and systemic toxicities. Antibody-drug conjugates (ADCs) are one of the most rapidly expanding classes of anti-cancer therapeutics with 13 presently approved by the FDA. Importantly, ADCs represent a promising therapeutic option with the potential to overcome traditional HER-targeted therapy resistance by delivering highly potent cytotoxins specifically to HER-overexpressing cancer cells and exerting both mAb- and payload-mediated antitumor efficacy. The clinical utility of HER-targeted ADCs is exemplified by the immense success of HER2-targeted ADCs including trastuzumab emtansine and trastuzumab deruxtecan. Still, strategies to improve upon existing HER2-targeted ADCs as well as the development of ADCs against other HER family members, particularly EGFR and HER3, are of great interest. To date, no HER4-targeting ADCs have been reported. In this review, we extensively detail clinical-stage EGFR-, HER2-, and HER3-targeting monospecific ADCs as well as novel clinical and pre-clinical bispecific ADCs (bsADCs) directed against this receptor family. We close by discussing nascent trends in the development of HER-targeting ADCs, including novel ADC payloads and HER ligand-targeted ADCs.

Synthesis and Preclinical Evaluation of [Methylpiperazine-11C]brigatinib as a PET Tracer Targeting Both Mutated Epidermal Growth Factor Receptor and Anaplastic Lymphoma Kinase

Brigatinib, a tyrosine kinase inhibitor (TKI) with specificity for gene rearranged anaplastic lymphoma kinase (ALK), such as the EML4-ALK, has shown a potential to inhibit mutated epidermal growth factor receptor (EGFR). In this study, N-desmethyl brigatinib was successfully synthesized as a precursor in five steps. Radiolabeling with [11C]methyl iodide produced [methylpiperazine-11C]brigatinib in a 10 ± 2% radiochemical yield, 91 ± 17 GBq/μmol molar activity, and ≥95% radiochemical purity in 49 ± 4 min. [Methylpiperazine-11C]brigatinib was evaluated in non-small cell lung cancer xenografted female nu/nu mice. An hour post-injection (p.i.), 87% of the total radioactivity in plasma originated from intact [methylpiperazine-11C]brigatinib. Significant differences in tumor uptake were observed between the endogenously EML4-ALK mutated H2228 and the control xenograft A549. The tumor-to-blood ratio in H2228 xenografts could be reduced by pretreatment with ALK inhibitor crizotinib. Tracer uptake in EGFR Del19 mutated HCC827 and EML4-ALK fusion A549 was not significantly different from uptake in A549 xenografts.

Synthesis and preclinical evaluation of two osimertinib isotopologues labeled with carbon-11 as PET tracers targeting the tyrosine kinase domain of the epidermal growth factor receptor

INTRODUCTION

Osimertinib is a third-generation tyrosine kinase inhibitor (TKI) that is able to inhibit the EGFR treatment resistance mutation T790M and primary EGFR mutations Del19 and L858R. The aim of the study was to evaluate the potential of carbon-11 labeled osimertinib to be used as a tracer for the PET imaging of tumors bearing the T790M mutation.

METHODS

Osimertinib was labeled with carbon-11 at two positions, and the effect of the labeling position on the metabolism and biodistribution was studied in female nu/nu mice. The mutation status specificity of osimertinib was confirmed in vitro in a cell growth inhibition experiment, and the tumor-targeting potential of the carbon-11 isotopologues was evaluated using female nu/nu mice xenografted with NSCLC cell lines; the wild-type EGFR expressing A549, the primary Del19 EGFR mutated HCC827 and the resistance T790M/L858R mutated H1975. One of the osimertinib tracers was selected based on the results acquired and evaluated for tracer specificity and selectivity by assessment of tumor uptake in a PET study where HCC827 tumor-bearing mice were pretreated with osimertinib or afatinib.

RESULTS

[Methylindole-¹¹C]- and [dimethylamine-¹¹C]osimertinib were synthesized by ¹¹C-methylation of precursors AZ5104 and AZ7550, respectively. Rapid metabolism of both analogs of [¹¹C]osimertinib was observed. Although the tumor uptake and retention of [methylindole-¹¹C]- and [dimethylamine-¹¹C]osimertinib in tumors were similar, the tumor-to-muscle ratios appeared to be higher for [methylindole-¹¹C]osimertinib. The highest uptake, tumor-to-blood, and tumor-to-muscle ratio were observed in the Del19 EGFR mutated HCC827 tumors. However, the specificity and selectivity of [methylindole-¹¹C]osimertinib PET could not be demonstrated in HCC827 tumors. The uptake of [methylindole-¹¹C]osimertinib was not significantly higher in T790M resistance mutated H1975 xenografts compared to the negative control cell line A549.

CONCLUSIONS

Osimertinib was successfully labeled at two positions with carbon-11, yielding two EGFR PET tracers, [methylindole-¹¹C]osimertinib and [dimethylamine-¹¹C]osimertinib. The preclinical evaluation demonstrated uptake and retention in three NSCLC xenografts; A549, HCC827, and H1975. The highest uptake was observed in the primary Del19 EGFR mutated HCC827. The ability of [methylindole-¹¹C]osimertinib to distinguish between the T790M resistance mutated H1975 xenografts and the wild-type EGFR expressing A549 could not be confirmed in the ex vivo study.

A Short Review on Miniaturized Biosensors for the Detection of Nucleic Acid Biomarkers

Even today, most biomarker testing is executed in centralized, dedicated laboratories using bulky instruments, automated analyzers, and increased analysis time and expenses. The development of miniaturized, faster, low-cost microdevices is immensely anticipated for substituting for these conventional laboratory-oriented assays and transferring diagnostic results directly onto the patient's smartphone using a cloud server. Pioneering biosensor-based approaches might make it possible to test biomarkers with reliability in a decentralized setting, but there are still a number of issues and restrictions that must be resolved before the development and use of several biosensors for the proper understanding of the measured biomarkers of numerous bioanalytes such as DNA, RNA, urine, and blood. One of the most promising processes to address some of the issues relating to the growing demand for susceptible, quick, and affordable analysis techniques in medical diagnostics is the creation of biosensors. This article critically discusses a short review of biosensors used for detecting nucleic acid biomarkers, and their use in biomedical prognostics will be addressed while considering several essential characteristics.

Absence of copy number gain of EGFR: A possible predictive marker of long-term response to afatinib

Treatment efficacy of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is diverse even in non-small cell lung cancer (NSCLC) patients with EGFR activating mutations. Extraordinary long-term responses sustained over 3 years among NSCLC patients treated with afatinib, an EGFR-TKI, have been reported, but how to predict such long survivors has not been clarified. A multi-institutional prospective observational study, based on comprehensive genomic examination performed with next-generation sequencing of circulating tumor DNA (ctDNA), was conducted to identify potential predictive markers of long-term response to afatinib. Twenty-nine patients with advanced stage NSCLC and EGFR driver mutations detected by standard techniques were enrolled in the study. ctDNA from plasma collected before afatinib treatment was analyzed by Guardant360. ctDNA was detected in 25 of the 29 samples. Median progression-free survival was shorter in patients whose tumors had EGFR copy number gain (7.0 vs 23.0 months, p = 0.022). The impact of EGFR copy number on cell proliferation and the antitumor effect of afatinib were evaluated using genome-editing lung cancer cell lines. HCC827 with EGFR amplification was relatively resistant to afatinib at concentrations below 0.5 nM, but genome-edited derivatives of HCC827 with decreased EGFR copy number demonstrated growth inhibition with 0.1 nM afatinib. The absence of EGFR copy number gain detected in ctDNA may be a predictive marker of long-term response to afatinib. Comprehensive genomic analysis could lead to a more accurate prediction of EGFR-TKI efficacy.

Endobronchial ultrasound-guided re-biopsy of non-small cell lung cancer with acquired resistance after EGFR tyrosine kinase inhibitor treatment

BACKGROUND

Few studies assessed the use of endobronchial ultrasound (EBUS)-guided re-biopsy for detecting the T790M mutation after epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) failure.

METHODS

A total of 2996 EBUS procedures were performed during the study period (January 2019-June 2022). In total, 44 consecutive patients who underwent EBUS-guided re-biopsy (56 procedures) for detecting the T790M mutation were analyzed. The success rates and T790M mutation frequencies were analyzed according to the re-biopsy site and EBUS method. Multivariate logistic regression analyses were used to identify factors affecting the likelihood of the T790M mutation.

RESULTS

The success rates for the mutation analyses using EBUS with a guide-sheath (EBUS-GS), EBUS guided transbronchial needle aspiration (EBUS-TBNA), and EBUS-GS with EBUS-TBNA for re-biopsy were 80.6% (29/36), 93.3% (14/15), and 100% (5/5), respectively. Patients who underwent lymph node biopsy using EBUS-TBNA had an increased rates of the T790M mutation compared with those undergoing lung biopsy using EBUS-GS (EBUS-TBNA, 60.0%; EBUS-GS with EBUS-TBNA, 40.0%; EBUS-GS, 11.1%; p < 0.001). In multivariate analysis, the use of a first-generation EGFR-TKI (odds ratio [OR], 4.29; 95% confidence interval [CI], 1.05-17.58; p = 0.043) was associated with occurrence of the T790M mutation. Re-biopsy of the metastatic site tended to be associated with a higher T790M mutation rate. Mild hemoptysis occurred in 3.6% (2/56) of the patients.

CONCLUSIONS

EBUS-guided re-biopsy can be used for detecting the T790M mutation in patients who failed EGFR-TKI therapy. The T790M mutation frequency differed according to the re-biopsy site. The use of a first-generation EGFR-TKI was an independent predictor of the T790M mutation.

The Development of Positron Emission Tomography Tracers for In Vivo Targeting the Kinase Domain of the Epidermal Growth Factor Receptor

Multiple small molecule PET tracers have been developed for the imaging of the epidermal growth factor receptor (EGFR). These tracers target the tyrosine kinase (TK) domain of the receptor and have been used for both quantifying EGFR expression and to differentiate between EGFR mutational statuses. However, the approaches for in vivo evaluation of these tracers are diverse and have resulted in data that are hard to compare. In this review, we analyze the historical development of the in vivo evaluation approaches, starting from the first EGFR TK PET tracer [11C]PD153035 to tracers developed based on TK inhibitors used for the clinical treatment of mutated EGFR expressing non-small cell lung cancer like [11C]erlotinib and [18F]afatinib. The evaluation of each tracer has been compiled to allow for a comparison between studies and ultimately between tracers. The main challenges for each group of tracers are thereafter discussed. Finally, this review addresses the challenges that need to be overcome to be able to efficiently drive EGFR PET imaging forward.

Integration of liquid biopsy and pharmacogenomics for precision therapy of EGFR mutant and resistant lung cancers

The advent of molecular profiling has revolutionized the treatment of lung cancer by comprehensively delineating the genomic landscape of the epidermal growth factor receptor (EGFR) gene. Drug resistance caused by EGFR mutations and genetic polymorphisms of drug metabolizing enzymes and transporters impedes effective treatment of EGFR mutant and resistant lung cancer. This review appraises current literature, opportunities, and challenges associated with liquid biopsy and pharmacogenomic (PGx) testing as precision therapy tools in the management of EGFR mutant and resistant lung cancers. Liquid biopsy could play a potential role in selection of precise tyrosine kinase inhibitor (TKI) therapies during different phases of lung cancer treatment. This selection will be based on the driver EGFR mutational status, as well as monitoring the development of potential EGFR mutations arising during or after TKIs treatment, since some of these new mutations may be druggable targets for alternative TKIs. Several studies have identified the utility of liquid biopsy in the identification of EGFR driver and acquired resistance with good sensitivities for various blood-based biomarkers. With a plethora of sequencing technologies and platforms available currently, further evaluations using randomized controlled trials (RCTs) in multicentric, multiethnic and larger patient cohorts could enable optimization of liquid-based assays for the detection of EGFR mutations, and support testing of CYP450 enzymes and drug transporter polymorphisms to guide precise dosing of EGFR TKIs.

Biomarker subset analysis of a phase IIIb, open-label study of afatinib in EGFR tyrosine kinase inhibitor-naive patients with EGFRm+ non-small-cell lung cancer

Aim: To explore the relationship between mutations in cfDNA and response to afatinib. Patients & methods: In total, 64 patients from one Chinese site with locally advanced/metastatic EGFRm+ non-small-cell lung cancer, who received afatinib 40 mg once daily, were included. Results: Overall, 33 (82.5%) patients became EGFRm- by visit 3; median progression-free survival was longer in these patients vs those who did not (11.0 vs 5.5 months). Progression-free survival was shorter in 42 (45.2%) patients with non-EGFR co-mutations at baseline vs those without (8.1 vs 12.5 months). Neither difference was significant. Conclusion: Afatinib provided clinical benefit for patients with EGFRm+ non-small-cell lung cancer across all subgroups. EGFRm status assessment in plasma cfDNA is a useful method of monitoring treatment.

Overall Treatment Strategy for Patients With Metastatic NSCLC With Activating EGFR Mutations

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) are standard of care in the first-line (1L) setting for patients with metastatic non-small cell lung cancer (mNSCLC) with activating EGFR mutations. EGFR-activating mutations are a predictive factor for response to EGFR-TKIs. Meta-analyses have shown that patients with exon 21_L858R mutations exhibit reduced sensitivity to EGFR-TKIs, resulting in inferior patient outcomes compared to those with exon 19 deletion mutations, with worse overall survival, progression-free survival, objective response, and disease control rates. Clinical activity observed with 1L therapy with first-generation (1G), second-generation (2G), and third-generation (3G) EGFR-TKIs is not permanent, and resistance inevitably develops in all cases, supporting the importance of overall treatment planning. The introduction of the 3G EGFR-TKI, osimertinib, provides an opportunity to overcome T790M-mediated resistance to 1G, and 2G EGFR-TKIs. Additionally, with the use of osimertinib, fewer T790M mutations are being detected as T790M is not a reported resistance mechanism to 3G EGFR-TKIs. However, there are currently no approved targeted therapies after 3G EGFR-TKIs. In order to further improve patient outcomes, there is a need to explore additional options for the overall treatment strategy for patients, including 1L and beyond. Combination of vascular endothelial growth factor (VEGF) inhibitors and EGFR-TKIs or chemotherapy and EGFR-TKIs may be a potential therapeutic approach in the 1L setting. This review discusses current treatment options for mNSCLC with activating EGFR mutations based on tumor, patient, and treatment characteristics and how an overall treatment plan may be developed.

Selective FGFR/FGF pathway inhibitors: inhibition strategies, clinical activities, resistance mutations, and future directions

Introduction: Fibroblast growth factor receptor (FGFR)/fibroblast growth factor (FGF) is a pathway characterized by recurring alterations in cancer. Its dysregulations enhance cancer cell proliferation, survival, migration and invasion, as well as angiogenesis and immune evasion.Areas covered: FGFR/FGF selective inhibitors belong to a broad class of drugs with some being approved for specific indications and others under investigation in ongoing phase I and II clinical trials. In this review, all available clinical data from trials on selective FGFR/FGF inhibitors as well as described resistance mutations and mechanisms are presented. FGFR/FGF pathway inhibitors are classified according to the mechanism they employ to dampen/suppress signaling and to the preferred FGFR binding mode when X-ray crystal structure is available.Expert opinion: Data presented suggests the general actionability of FGFR1,2,3 mutations and fusions across histologies, whereas FGFR1,2,3 amplifications alone are poor predictors of response to tyrosine kinase inhibitors. Overexpression on immunohistochemistry (IHC) of FGF19, the stimulatory ligand of FGFR4, can predict response to FGFR selective inhibitors in hepatocellular carcinoma. Whereas IHC overexpression of FGFR1,2,3 is not sufficient to predict benefit from FGFR inhibitors across solid tumors. FGFR1,2,3 mRNA overexpression can predict response even in absence of structural alteration. Data on resistance mutations suggests the need for new inhibitors to overcome gatekeeper mutations.

The Liquid Biopsy for Lung Cancer: State of the Art, Limitations and Future Developments

Simple Summary

During the development and progression of lung tumors, processes such as necrosis and vascular invasion shed tumor cells or cellular components into various fluid compartments. Liquid biopsies consist of obtaining a bodily fluid, typically peripheral blood, in order to isolate and investigate these shed tumor constituents. Circulating tumor cells (CTCs) are one such constituent, which can be isolated from blood and can act as a diagnostic aid and provide valuable prognostic information. Liquid-based biopsies may also have a potential future role in lung cancer screening. Circulating tumor DNA (ctDNA) is found in small quantities in blood and, with the recent development of sensitive molecular and sequencing technologies, can be used to directly detect actionable genetic alterations or monitor for resistance mutations and guide clinical management. While potential benefits of liquid biopsies are promising, they are not without limitations. In this review, we summarize the current state and limitations of CTCs and ctDNA and possible future directions.

Abstract

Lung cancer is a leading cause of cancer-related deaths, contributing to 18.4% of cancer deaths globally. Treatment of non-small cell lung carcinoma has seen rapid progression with targeted therapies tailored to specific genetic drivers. However, identifying genetic alterations can be difficult due to lack of tissue, inaccessible tumors and the risk of complications for the patient with serial tissue sampling. The liquid biopsy provides a minimally invasive method which can obtain circulating biomarkers shed from the tumor and could be a safer alternative to tissue biopsy. While tissue biopsy remains the gold standard, liquid biopsies could be very beneficial where serial sampling is required, such as monitoring disease progression or development of resistance mutations to current targeted therapies. Liquid biopsies also have a potential role in identifying patients at risk of relapse post treatment and as a component of future lung cancer screening protocols. Rapid developments have led to multiple platforms for isolating circulating tumor cells (CTCs) and detecting circulating tumor DNA (ctDNA); however, standardization is lacking, especially in lung carcinoma. Additionally, clonal hematopoiesis of uncertain clinical significance must be taken into consideration in genetic sequencing, as it introduces the potential for false positives. Various biomarkers have been investigated in liquid biopsies; however, in this review, we will concentrate on the current use of ctDNA and CTCs, focusing on the clinical relevance, current and possible future applications and limitations of each.

Using Liposomes to Alleviate the Toxicity of Chelerythrine, a Natural PKC Inhibitor, in Treating Non-Small Cell Lung Cancer

Aim of the Study

CHE can inhibit the proliferation of lung cancer cells and induce apoptosis. However, despite having in vivo toxicity, CHE has not been thoroughly investigated in term of its in vivo antitumor effect. The present study evaluated the antitumor effect of CHE on non-small cell lung cancer cell line HCC827.

Methods

The antitumor effect of CHE on HCC827 was evaluated, and its potential work mechanism was investigated. CHE long circulation liposomes (CHELPs) modified with polyethylene glycol have been optimized and characterized by in vivo pharmacokinetic studies. A HCC827 xenograft model was developed on BALB/c nude mice for the assessment of the effects of CHE and CHELP.

Results

CHE might inhibit HCC827 growth through the ROS/PKC-ϵ/caspase 3 pathway and glycolysis. The optimized CHELP remained stable after storage for 10 days at 4°C and exhibited sustained drug release, showing approximately one-fifteenth of the in vivo clearance rate and 86 times the absorption concentration of free drug. While increasing the bioavailability of CHE, CHELP showed a good therapeutic effect on HCC827 tumor-bearing nude mice and reduced the toxicity of the free drug, improving the safety of CHE.

Conclusions

CHE is a candidate drug for NSCLC, and liposomes are effective in alleviating the toxicity of CHE.

Afatinib for the first-line treatment of EGFR mutation-positive NSCLC in China: a review of clinical data

Mutations in the EGFR gene are particularly prevalent among Chinese patients with non-small-cell lung carcinoma. Six EGFR tyrosine kinase inhibitors are approved for the first-line treatment of EGFR mutation-positive non-small-cell lung carcinoma in China, which poses questions about which agent is most suitable for a particular patient. In this article, we review available clinical trial and real-world data with afatinib in Chinese patients. We assess its efficacy and safety in key patient subgroups such as those with uncommon mutations or brain metastases. We also consider possible subsequent therapies following afatinib. Encouragingly, available data suggest that sequential afatinib and osimertinib confer prolonged overall time to failure of almost 4 years in Asian patients, and represents a viable option in this setting.

Development and Challenges of the Discovery of HER2 Inhibitors

The treatment of cancer has always been a major problem in the world. Some cancers cannot be treated with surgery, but only with cancer drugs. Among many cancer drugs, small molecule inhibitors play an irreplaceable role. HER2 is one of the HER families, and the development of HER2 inhibitors has made a huge contribution to the treatment of cancer. Some HER2 inhibitors are already on the market, and some HER2 inhibitors are undergoing clinical research. The design, synthesis and development of new HER2 inhibitors targeting different targets are also ongoing, and some are even under clinical research. The HER2 inhibitors that are on the market have developed resistance, which brings great challenges to the HER2 inhibitor development in the future. This article reviews the development and challenges of the discovery of HER2 inhibitors.

Medicinal Chemistry Strategies for the Development of Kinase Inhibitors Targeting Point Mutations

Clinically acquired resistance to small molecule kinase inhibitors (SMKIs) has become a major "unmet clinical need" in cancer therapy. To date, there are six SMKIs to be approved for the treatment of cancer patients through targeting of clinically acquired resistance caused by on-target mutations. These are mainly focused on the mutant kinases Bcr-Abl T315I, EGFR T790M, and ALK L1196M. Herein, we summarize the major medicinal chemistry strategies employed in the discovery of these representative SMKIs, such as avoiding steric hindrance, making additional interactions with mutated residues, and forming a covalent bond with an active site cysteine to override resistance observed for reversible inhibitors. Additionally, we also briefly describe allosteric kinase inhibitors and proteolysis targeting chimera (PROTAC) as two other potential strategies while addressing future opportunities in this area.

Advances in targeting acquired resistance mechanisms to epidermal growth factor receptor tyrosine kinase inhibitors

Next-generation sequencing (NGS) of tumor samples and circulating tumor DNA has revolutionized diagnostic and therapeutic strategies in lung cancer. The identification of the epidermal growth factor receptor (EGFR) oncogenic driver has translated into successful therapy of advanced lung cancer using EGFR tyrosine kinase inhibitors (TKI). Unfortunately, responses are limited by acquired mechanisms of resistance. We review herein the current landscape of acquired resistance mechanisms to EGFR-TKI therapy and recent advances in therapeutic strategies to overcome acquired resistance.

Differential significance of molecular subtypes which were classified into EGFR exon 19 deletion on the first line afatinib monotherapy

BACKGROUND

Epidermal growth factor receptor (EGFR)-sensitizing mutation, exon 19 deletion consists of several molecular variants. Influences of these variants on clinical response to EGFR tyrosine kinase inhibitors remain elusive.

METHODS

West Japan Oncology Group 8114LTR is a prospective, multi-institutional biomarker study. Treatment naïve, advanced non-small-cell lung cancer patients with EGFR-sensitizing mutation received afatinib monotherapy. We conducted a preplanned subset analysis of patients harboring exon 19 deletion. Tumor tissue exon 19 deletion molecular variants were identified by blocking-oligo-dependent polymerase chain reaction (PCR) and by Luminex Technology. Plasma cfDNA was also obtained before and after the treatment and EGFR mutations were detected with multiplexed, pico-droplet digital PCR assay.

RESULTS

Among 57 registered patients, twenty-nine patients were exon 19 deletion. Tissue DNA and cfDNA were available in 26 patients. Among the detected seven molecular variants, the most frequent was p.E746_A750delELREA (65.4%). According to the various classifications of molecular variants, twenty one (80.8%) were classified into 15-nucleotide deletion, one (3.8%) into 18-nucleotide deletion, and four patients (15.4%) into other insertion/substitution variant subgroups. The patient subgroup with 15-nucleotide deletion showed significantly longer progression-free survival than patients in other mixed insertion/substitution variant subgroup (p = 0.0244).

CONCLUSIONS

The clinical significance of molecular variants of exon 19 deletion on the first line afatinib monotherapy is reported here for the first time. Further investigation is needed for development of better therapeutic strategies.

TRIAL REGISTRATION

This trial was registered at UMIN Clinical Trials Registry at 2014/12/4 (UMIN000015847).

Front-line Therapy in Advanced Non-Small Cell Lung Cancer With Sensitive Epidermal Growth Factor Receptor Mutations: A Network Meta-analysis

PURPOSE

Several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) were firmly established as front-line treatment for non-small cell lung cancer (NSCLC) that harbored an activating EGFR mutation. Gefitinib or erlotinib was considered the standard of care. TKI-based combination therapy has been investigated and has shown encouraging results.

METHODS

The PubMed and EMBASE databases, the Cochrane Central Register of Controlled Trials, and meeting abstracts were screened for relevant studies between January 2000 and February 2019. Prospective randomized controlled trials were included that investigated EGFR TKIs (alone or in combination) in untreated patients with NSCLC whose tumors had sensitive EGFR mutations. A frequentist random effects network meta-analysis model was conducted to assess objective response rate, progression-free survival, and overall survival. P-score was used to rank treatment effects.

FINDINGS

Seventeen trials involving 9 treatments and 4373 patients were included. Heterogeneity existed in the network analysis. For progression-free survival, the top 3 treatments were osimertinib, standard of care plus chemotherapy, and standard of care plus bevacizumab; corresponding p-scores were 0.88, 0.79, and 0.75, respectively. For overall survival, the top 3 treatments were standard of care plus chemotherapy, osimertinib, and dacomitinib; corresponding p-scores were 0.89, 0.85, and 0.64. TKI-based combination therapy caused more toxicity than a TKI alone.

IMPLICATIONS

Osimertinib seemed to be a better option as upfront therapy for EGFR-mutant NSCLC in terms of efficacy and tolerability.

Afatinib for the Treatment of NSCLC Harboring Uncommon EGFR Mutations: A Database of 693 Cases

INTRODUCTION

Limited clinical data are available regarding the efficacy of EGFR tyrosine kinase inhibitors (EGFR TKIs) in patients with NSCLC harboring uncommon EGFR mutations. This pooled analysis assessed the activity of afatinib in 693 patients with tumors harboring uncommon EGFR mutations treated in randomized clinical trials, compassionate-use and expanded-access programs, phase IIIb trials, noninterventional trials, and case series or studies.

METHODS

Patients had uncommon EGFR mutations, which were categorized as follows: (1) T790M; (2) exon 20 insertions; (3) "major" uncommon mutations (G719X, L861Q, and S768I, with or without any other mutation except T790M or an exon 20 insertion); (4) compound mutations; and (5) other uncommon mutations. Key end points were overall response rate (ORR), duration of response, and time to treatment failure (TTF).

RESULTS

In EGFR TKI-naive patients (n = 315), afatinib demonstrated activity against major uncommon mutations (median TTF = 10.8 mo; 95% confidence interval [CI]: 8.1-16.6; ORR = 60.0%), compound mutations (median TTF = 14.7 mo; 95% CI: 6.8-18.5; ORR = 77.1%), other uncommon mutations (median TTF = 4.5 mo; 95% CI: 2.9-9.7; ORR = 65.2%), and some exon 20 insertions (median TTF = 4.2 mo; 95% CI: 2.8-5.3; ORR = 24.3%). The median duration of response for major uncommon mutations, compound mutations, other uncommon mutations, and some exon 20 insertions was 17.1, 16.6, 9.0, and 11.9 months, respectively. Activity of afatinib was also observed in EGFR TKI-pretreated patients (n = 378). A searchable database of these outcomes by individual genotype was generated.

CONCLUSIONS

Afatinib has clinical activity in NSCLC against major uncommon and compound EGFR mutations. It also has broad activity against other uncommon EGFR mutations and some exon 20 insertions. The data support the use of afatinib in these settings.

Tyrosine Kinase Inhibitors for the Treatment of EGFR Mutation-Positive Non-Small-Cell Lung Cancer: A Clash of the Generations

The availability of 3 generations of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) with different pharmacologic characteristics and clinical profiles has provided oncologists with a potentially confusing choice for the treatment of EGFR mutation-positive non-small-cell lung cancer. Although recent head-to-head clinical trials have demonstrated improved efficacy with second-generation (ie, afatinib, dacomitinib) and third-generation (ie, osimertinib) TKIs compared with the first-generation TKIs (eg, erlotinib, gefitinib), acquired resistance has been inevitable, regardless of which agent has been chosen as first-line therapy. Thus, the potential availability of subsequent treatment options is an important consideration. Recent data have demonstrated that osimertinib confers an overall survival benefit compared with first-generation EGFR TKIs, and dacomitinib has shown an overall survival benefit compared with gefitinib in an exploratory analysis. However, the relative benefits of different sequential EGFR-TKI regimens, especially those involving second- and third-generation agents, have remained uncertain and require prospective evaluation. Few such data currently exist to inform treatment choices. In the present review, we examined the pharmacologic characteristics and current clinical data for EGFR TKIs, including emerging information on the molecular mechanisms of resistance across the different generations of TKIs. Given the uncertainties regarding the optimal treatment choice, we have focused on the factors that might help determine the treatment decisions, such as efficacy and safety in patient subgroups. We also discussed the emerging real-world data, which have provided some insights into the benefits of sequential regimens in everyday clinical practice.

Incidence of T790M in Patients With NSCLC Progressed to Gefitinib, Erlotinib, and Afatinib: A Study on Circulating Cell-free DNA

BACKGROUND

Insights into the mechanism of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) could provide important information for further patient management, including the choice of second-line treatment. The EGFR T790M mutation is the most common mechanism of resistance to first- and second-generation EGFR TKIs. Owing to its biologic relevance in the response of non-small-cell lung cancer (NSCLC) to the selective pressure of treatment, the present study investigated whether the occurrence of T790M at progression differed among patients receiving gefitinib, erlotinib, or afatinib.

PATIENTS AND METHODS

The present retrospective study included patients with NSCLC with an EGFR activating mutation, who had received gefitinib, erlotinib, or afatinib as first-line treatment. Plasma samples for the analysis of cell-free DNA were taken at disease progression and analyzed using a digital droplet polymerase chain reaction EGFR mutation assay.

RESULTS

A total of 83 patients were enrolled; 42 had received gefitinib or erlotinib and 41afatinib. The patient characteristics were comparable across the 2 groups. The median time to progression (TTP) was 14.4 months for the gefitinib and erlotinib group and 10.2 months for the afatinib group (P = .09). Of the 83 patients, 47 (56.6%) were positive for the T790M in plasma. A greater incidence of T790M was observed in patients with progression during gefitinib or erlotinib therapy compared with patients treated with afatinib (33 [79%] vs. 14 [34%], respectively; odds ratio, 7.1; 95% confidence interval, 2.7-18.5; P = .0001).

CONCLUSIONS

Although gefitinib, erlotinib, and afatinib showed a comparable TTP in patients receiving first-line therapy, the incidence of T790M differed among them, as demonstrated by the present study, which could have implications for the choice of second-line treatment.