Phase I dose-escalation study of the pan-HER inhibitor, PF299804, in patients with advanced malignant solid tumors

Supramolecular fluorescence sensor array used for the analysis of tyrosine kinase inhibitors in biological fluids and cell imaging

Tyrosine kinase inhibitors (TKIs) are commonly used in tumor targeting therapy. However, the rapid analysis of TKIs remains a significant challenge, especially in complex biological fluid environments. In this work, we have constructed a supramolecular fluorescence sensor array based on a cucurbituril-dye host-guest complex. The binding affinity between the three complexes and each TKI is different, resulting in different cross-response signals of the complexes to the fluorescence of each TKI. Combined with linear discriminant analysis(LDA), five kinds of TKIs can be well identified. The supramolecular fluorescence sensor array could accurately identify and distinguish the five TKIs in water and could classify mixtures containing different concentrations of TKIs in serum. The concentration and Factor 1 exhibited a good linear relationship and the detection limit (LOD) was as low as 10-7 mol L-1. The method has good reproducibility and stability. In addition, the differentiation of four clinical concentrations of first-generation TKIs further validated the potential application of arrays in drug monitoring. Finally, our proposed array enabled drug imaging in living cells. Our array platform provided the foundation for the rapid and easy monitoring of 4-anilinoquinazoline TKIs.

Effects of H2-Receptor Antagonists on the Exposure of Dacomitinib

Dacomitinib is an irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor indicated for the treatment of patients with advanced non-small-cell lung cancer (NSCLC) and EGFR-activating mutations. Proton-pump inhibitors decreased dacomitinib exposure. This analysis summarizes the effect of Histamine-2 receptor antagonists (H2RAs) on dacomitinib exposure. A within-patient comparison of the steady-state trough concentrations (Ctrough,ss) of dacomitinib and its active metabolite and active moiety with and without concomitant use of H2RAs was conducted using a linear mixed effects model with pooled data from 11 clinical studies in patients with NSCLC. An oral absorption physiologically based pharmacokinetic (PBPK) model was constructed and verified using clinical pharmacokinetic (PK) data after a single dose of dacomitinib in healthy volunteers to estimate the effect of gastric pH altered by an H2RA on dacomitinib's PKs. The adjusted geometric mean of the dacomitinib Ctrough,ss of the dacomitinib parent, metabolite and active moiety following co-administration with an H2RA was approximately 86%, 104% and 100% relative to that following dacomitinib 45 mg administration without an H2RA (p > 0.05). The PBPK modeling showed negligible change in dacomitinib maximum concentration (Cmax) and area under the drug concentration-time curve (AUC) over 0-24 h after H2RA administration when compared with those administered dacomitinib alone. Co-administration of an H2RA with dacomitinib is not expected to have any clinically relevant effect on dacomitinib exposure.

EGFR exon20 insertion mutations in non-small cell lung cancer: Clinical implications and recent advances in targeted therapies

The advent of targeted therapies for oncogenic mutations has led to a major paradigm shift in the management of non-small cell lung cancer (NSCLC). Molecular targets, such as epidermal growth factor receptor (EGFR)-activating mutations in the region of exons 18 through 21 are the most common oncogenic driver in NSCLC. Classical activating mutations, such as in-frame deletions in exon 19 and point mutations in exon 21 (L858R), are strong predictors for good clinical response to the approved EGFR-tyrosine kinase inhibitors (EGFR-TKIs). However, low frequency mutations occurring within exon 20 (ex20ins) have poorer responses to first/second generation EGFR-TKIs. Moreover, patients with NSCLC harboring EGFR ex20ins are known to have poorer prognosis than those with other EGFR-TKI sensitive mutations, leading to unmet clinical need of novel specific therapeutic options. Rapid changes in molecular diagnostics identifying specific causes have hastened the translation of diagnostic recommendations into clinical practice. Emergence of treatment strategies targeting EGFR ex20ins, such as newer EGFR-TKIs with increased specificity and novel approaches using bispecific monoclonal antibodies, may hold promising therapeutic options in the near future. In this review, we describe the structural, molecular characteristics, and detection strategies of EGFR ex20ins mutations and summarize the latest clinical data on approved treatments and emerging therapies for patients with NSCLC harboring EGFR ex20ins mutations. Further, we will discuss the response heterogeneity of ex20ins mutations to new drugs and acquired drug resistance mechanisms.

Efficacy and safety of dacomitinib in treatment-naïve patients with advanced NSCLC harboring uncommon EGFR mutation: an ambispective cohort study

BACKGROUND

About 10% of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations are harbored as uncommon mutations. This study aimed to explore the efficacy and safety of dacomitinib, a second-generation EGFR tyrosine kinase inhibitor (EGFR-TKIs), in treating uncommon EGFR-mutated advanced NSCLC.

METHODS

Treatment-naïve advanced NSCLC patients treated with dacomitinib at Hunan Cancer Hospital with uncommon EGFR mutations were evaluated. The primary endpoint was progression-free survival (PFS). Secondary end points included overall survival (OS), objective response rate (ORR), disease control rate (DCR) and safety.

RESULT

Between December 2019 and December 2021, a total of 16 patients was included. Median PFS was 14.0 (95% CI 4.32-23.7) months, and median OS was not reached. ORR was 68.8% (95% CI 41.3 to 89.0%) and DCR was 93.8% (95%CI 69.8 to 99.8%), including three achieving complete remission (CR) and eight achieving partial remission (PR). Median PFS for patients with brain metastasis was 9.0 (95%CI 6.9 to 11.1) months. Intracranial ORR was 100%, including 2 CR and 4 PR. Major treatment-related adverse events (TRAEs) included rash (87.5%), paronychia (62.5%), oral ulcers (50.0%), and diarrhea (50.0%), none of which were ≥ grade 3 TRAEs.

CONCLUSIONS

Dacomitinib showed good activity and manageable toxicity in NSCLC patients with uncommon EGFR mutations.

The treatment of patients with non-small cell lung cancer carrying uncommon EGFR mutations, HER2 mutations, or brain metastases: a systematic review of pre-clinical and clinical findings for dacomitinib

Background

Accumulating evidence has shown that dacomitinib has potential activities for patients with non-small cell lung cancer (NSCLC) harboring uncommon epidermal growth factor receptor (EGFR) mutations, human epidermal growth factor receptor 2 (HER2) mutations, or central nervous system (CNS) metastases.

Methods

This study aimed to give a systematic review on its potential applications in the above settings by searching MEDLINE/PubMed, Embase, Cochrane Library, American Society of Clinical Oncology.org, European Society for Medical Oncology.org, and ClinicalTrials.gov.

Results

The literature search yielded 649 publications in total. According to our findings, dacomitinib exhibited promising efficacy in patients with major uncommon EGFR mutations (including G719X, S768I, and L861Q). Both EGFR exon 20 insertional mutation (Ex20ins) and HER2 Ex20ins demonstrated significant internal heterogeneity in response to dacomitinib, among which specific subtypes (including EGFR D770delinsGY, A763_Y764insFQEA, and HER2 M774delinsWLV) were highly sensitive. Other uncommon EGFR mutations including 18del and L747P have also been shown responsive to dacomitinib. Interestingly, limited studies suggested dacomitinib application on certain first or third generation tyrosine kinase inhibitors (TKIs)' resistant secondary mutations. Last but not least, both pre-clinical and clinical data indicated that dacomitinib has an encouraging intracranial tumor control ability, regardless of uncommon mutations.

Conclusions

Dacomitinib demonstrated good disease control on patients with NSCLC harboring major uncommon EGFR mutations and specific EGFR or HER2 mutation subtypes, and selective clinical application of dacomitinib is considerable in this setting, especially for those with intracranial metastases.

A Closer Look at EGFR Inhibitor Resistance in Non-Small Cell Lung Cancer through the Lens of Precision Medicine

The development of EGFR small-molecule inhibitors has provided significant benefit for the affected patient population. Unfortunately, current inhibitors are no curative therapy, and their development has been driven by on-target mutations that interfere with binding and thus inhibitory activity. Genomic studies have revealed that, in addition to these on-target mutations, there are also multiple off-target mechanisms of EGFR inhibitor resistance and novel therapeutics that can overcome these challenges are sought. Resistance to competitive 1st-generation and covalent 2nd- and 3rd-generation EGFR inhibitors is overall more complex than initially thought, and novel 4th-generation allosteric inhibitors are expected to suffer from a similar fate. Additional nongenetic mechanisms of resistance are significant and can include up to 50% of the escape pathways. These potential targets have gained recent interest and are usually not part of cancer panels that look for alterations in resistant patient specimen. We discuss the duality between genetic and nongenetic EGFR inhibitor drug resistance and summarize current team medicine approaches, wherein clinical developments, hand in hand with drug development research, drive potential opportunities for combination therapy.

Targeting exon 20 insertion mutations in lung cancer

PURPOSE OF REVIEW

The application of tyrosine kinase inhibitor (TKI) has successfully changed the standard of care in epidermal growth factor receptor ( EGFR ) positive non-small cell lung cancer. However, clinical survivals for patients with EGFR exon 20 insertions have failed to improve over the long period and the mutation appeared resistant to EGFR -TKIs. This overview focused on the current treatment strategies, summarized the emerging regimens for patients with EGFR exon 20 insertions, and demonstrated historical challenges and future development.

RECENT FINDING

Current clinical trials suggested that several regimens selectively-targeted EGFR exon 20 insertions presented potent antitumor activity, like mobocertinib and the bispecific anti- EGFR-MET monoclonal antibody amivantamab and were approved by Food and Drug Administration (FDA) in patients progressed beyond first-line treatment. Novel treatments, including DZD9008, CLN-081, revealed modest clinical efficacy as well and clinical trials are underway, which may lead to improvement of survival outcomes.

SUMMARY

Recent clinical evidence indicates that targeted therapies could improve survival benefits to some extent. More efforts on drug development are underway to bring higher response rates both extracranial and intracranial, sustained clinical remission, and better survival benefits.

Tissue- and cell-expression of druggable host proteins provide insights into repurposing drugs for COVID-19

Several human host proteins play important roles in the lifecycle of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Many drugs targeting these host proteins have been investigated as potential therapeutics for coronavirus disease 2019 (COVID-19). The tissue-specific expressions of selected host proteins were summarized using proteomics data retrieved from the Human Protein Atlas, ProteomicsDB, Human Proteome Map databases, and a clinical COVID-19 study. Protein expression features in different cell lines were summarized based on recent proteomics studies. The half-maximal effective concentration or half-maximal inhibitory concentration values were collected from in vitro studies. The pharmacokinetic data were mainly from studies in healthy subjects or non-COVID-19 patients. Considerable tissue-specific expression patterns were observed for several host proteins. ACE2 expression in the lungs was significantly lower than in many other tissues (e.g., the kidneys and intestines); TMPRSS2 expression in the lungs was significantly lower than in other tissues (e.g., the prostate and intestines). The expression levels of endocytosis-associated proteins CTSL, CLTC, NPC1, and PIKfyve in the lungs were comparable to or higher than most other tissues. TMPRSS2 expression was markedly different between cell lines, which could be associated with the cell-dependent antiviral activities of several drugs. Drug delivery receptor ICAM1 and CTSB were expressed at a higher level in the lungs than in other tissues. In conclusion, the cell- and tissue-specific proteomics data could help interpret the in vitro antiviral activities of host-directed drugs in various cells and aid the transition of the in vitro findings to clinical research to develop safe and effective therapeutics for COVID-19.

EGFR exon 20 insertion variants A763_Y764insFQEA and D770delinsGY confer favorable sensitivity to currently approved EGFR-specific tyrosine kinase inhibitors

Background: The EGFR exon 20 insertions (ex20ins) D770_N771insSVD and V769_D770insASV are most frequent in non-small-cell lung cancer (NSCLC) and are associated with intrinsic resistance to currently approved EGFR tyrosine kinase inhibitors (TKIs). A763_Y764insFQEA and D770delinsGY, respectively, account for 3%-8% and 2.0%-4.8% of EGFR ex20ins in NSCLC and are associated with a more favorable response to EGFR-specific TKIs as per case reports. The aim of this study was to elucidate the molecular structures of these mutants and their binding affinities to diverse EGFR TKIs and compare the clinical outcomes in NSCLC patients harboring these mutations. Methods: A real-world cohort study was conducted to evaluate and compare the clinical outcomes of EGFR TKIs among NSCLC patients with different EGFR ex20ins mutants in response to EGFR TKIs. The structures of A763_Y764insFQEA and D770delinsGY were also analyzed and drug binding simulations were performed. Results: With a median follow-up of 24.0 months, the first-line objective response rate (ORR), disease control rate (DCR), and median progression-free survival (PFS) were, respectively, 0 (0/16), 50.0% (8/16), and 2.07 months (95%CI, 0-6.25) in patients harboring D770_N771insSVD and V769_D770insASV variants and 33.3% (4/12), 83.3% (10/12), and 9.97 months (95%CI, 4.75-15.19) in patients with A763_Y764insFQEA and D770delinsGY variants. There was a significant difference between the PFS of these two subgroups (median, 9.97 vs.2.07 months, HR = 0.33, 95%CI, 0.13-0.85, p = 0.02). Similarly, the PFS was significantly longer after second-line treatment with EGFR TKIs in patients harboring A763_Y764insFQEA and D770delinsGY compared to those with other insertions (median, 6.77 vs.2.23 months, HR = 0.14, p < 0.001). Computational simulations indicated that A763_Y764insFQEA and D770delinsGY mutants were structurally similar to wild-type EGFR. In contrast, the C-helix and phosphate-binding loop of D770_N771insSVD and V769_D770insASV had shifted into the drug-binding pocket, resulting in significant steric hindrance and a lack of affinity for the currently approved EGFR inhibitors. Conclusion: NSCLC patients harboring A763_Y764insFQEA and D770delinsGY insertions of EGFR are responsive to the currently approved EGFR TKIs as opposed to patients with the D770_N771insSVD and V769_D770insASV variants. Therefore, A763_Y764insFQEA and D770delinsGY should be classified as active mutations among heterogeneous EGFR ex20ins subtypes and the carriers can be treated with the suitable EGFR TKIs.

Afatinib and Dacomitinib Efficacy, Safety, Progression Patterns, and Resistance Mechanisms in Patients with Non-Small Cell Lung Cancer Carrying Uncommon EGFR Mutations: A Comparative Cohort Study in China (AFANDA Study)

(1) Background: Afatinib has been approved for patients with non-small cell lung cancer (NSCLC) carrying major uncommon epidermal growth factor receptor gene (EGFR) mutations. Dacomitinib, another second-generation tyrosine kinase inhibitor, has also shown promising potential for uncommon EGFR mutations. However, no comparative study has been conducted. (2) Methods: Two cohorts were employed: the AFANDA cohort, an ambispective cohort including 121 patients with uncommon EGFR mutations admitted to two tertiary hospitals in China, and an external validation afatinib cohort (ex-AC), extracted from the Afatinib Uncommon EGFR Mutations Database (N = 1140). The AFANDA cohort was divided into an afatinib cohort (AC) and a dacomitinib cohort (DC) for internal exploration. Objective response rate (ORR), progression-free survival (PFS), and adverse events (AEs) were assessed for comparison. Progression patterns and resistance mechanisms were explored. (3) Results: In total, 286 patients with advanced NSCLC carrying uncommon EGFR mutations treated with afatinib or dacomitinib were enrolled, including 79 in the AFANDA cohort (44 in the DC, 35 in the AC) and 207 in the ex-AC. In internal exploration, the ORR of the DC was significantly higher than that of the AC (60.5 vs. 26.7%, p = 0.008), but there was no significant difference in median PFS between the DC and the AC (12.0 months vs. 10.0 months, p = 0.305). Multivariate analysis confirmed an independent favorable effect of dacomitinib on PFS (hazard ratio (HR), 1.909; p = 0.047). In external validation, multivariate analysis confirmed the independent prognostic role of dacomitinib in PFS (HR, 1.953; p = 0.029). Propensity score matching analysis confirmed the superiority of dacomitinib over afatinib in terms of PFS in both univariate and multivariate analyses. Toxicity profiling analysis suggested more G1 (p = 0.006), but fewer G3 (p = 0.036) AEs in the DC than in the AC. Progression patterns revealed that the incidence of intracranial progression in the AC was significantly higher than that in the DC (50 vs. 21.1%, p = 0.002). Drug resistance analysis indicated no significant difference in the occurrence of T790M between the AC and the DC (11.8 vs. 15.4%, p = 0.772). (4) Conclusions: Compared with afatinib, dacomitinib demonstrated a more favorable activity with manageable toxicity and different progression patterns in patients with NSCLC carrying uncommon EGFR mutations.

A Detouring Experience Not Recommended: Lessons Learned from PF00299804

Patients with mutant EGFR positive non-small cell lung cancer (NSCLC) benefit from tyrosine kinase inhibitor (TKI) treatment. However, all patients ultimately develop acquired resistance, half of which are attributed to the EGFR exon 20 T790M mutation. A landmark publication in Cancer Research in 2007 demonstrated improved drug potency and pan-human EGFR (HER) inhibition with PF00299804, a second-generation EGFR TKI. Compared with first-generation EGFR TKI, PF00299804 showed the ability to overcome T790M mutation in vitro and had the potential to improve treatment outcomes of patients with mutant EGFR-positive NSCLC. Here we review the preclinical and clinical development of PF00299804 and reflect on the lessons learned from this detouring experience. See related article by Engelman and colleagues, Cancer Res 2007;67:11924-32.

A randomized, open-label, two-cycle, two-crossover phase I clinical trial comparing the bioequivalence and safety of afatinib and Giotrif® in healthy Chinese subjects

OBJECTIVE

Afatinib is an oral, irreversible ErbB family blocker. It binds covalently to the kinase domains of epidermal growth factor (EGFR), HER2 and HER4, resulting in irreversible inhibition of tyrosine kinase autophosphorylation. Our trial compared the bioequivalence and safety between afatinib produced by Chia Tai Tianqing Pharmaceutical Group Co., Ltd. and Giotrif^® produced by Boehringer Ingelheim.

METHODS

Healthy Chinese subjects (N = 36) were randomly divided into two groups at a ratio of 1:1. There was a single dose per period of afatinib and Giotrif^®. The washout was set as 14 days. Plasma drug concentrations of afatinib and Giotrif^® were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Statistical analysis of major pharmacokinetic (PK) parameters was conducted to assess drug bioequivalence. In addition, we evaluated the safety of the drugs throughout the trial.

RESULTS

The geometric mean ratios (GMRs) of C_max, AUC_0-t, and AUC_0-∞ for afatinib and Giotrif^® were 102.80%, 101.83%, and 101.58%, respectively. The 90% confidence intervals (CIs) were all within 80%-125%, meeting the bioequivalence standards. In addition, both drugs showed a good safety profile during the trial.

CONCLUSION

This study showed that afatinib was bioequivalent to Giotrif^® in healthy Chinese subjects with well safety.

CHINESE CLINICAL TRIAL REGISTRY

This trial is registered at the Chinese Clinical Trial website ( http://www.chinadrugtrials.org.cn/index.html # CTR20171160).

Dacomitinib for Advanced Non-small Cell Lung Cancer Patients Harboring Major Uncommon EGFR Alterations: A Dual-Center, Single-Arm, Ambispective Cohort Study in China

Objective: Dacomitinib has been approved for non-small-cell lung cancer (NSCLC) patients harboring classical epidermal growth factor receptor (EGFR) mutations; however, clinical evidence of its activity on major uncommon EGFR mutations is currently limited.

Materials and methods: This was a dual-center, single-arm, ambispective cohort study in China. Patients with histologically confirmed metastatic or recurrent NSCLC harboring major uncommon EGFR mutations were eligible for the study. The objective response rate and disease control rate were determined by RECIST 1.1 every 1–2 months. Adverse events were assessed by CTCAE 5.0.

Results: In total, 32 NSCLC patients were enrolled between July 2020 and January 2022, and 18 (56.3%) patients received dacomitinib as first-line therapy. Median age was 64 years, and 20 (62.5%) were female. The mutations identified were G719X (n = 24; 75%), followed by L861X (n = 10; 31.3%), and S768I (n = 8; 25%). In the first-line setting, 72.2% of patients (13/18) had a confirmed partial response and 100% (18/18) had disease control, and the median progression-free survival (PFS) and overall survival (OS) were unreached. In the whole cohort, 56.3% of patients (18/32) had a confirmed partial response and 90.6% (29/32) had disease control, and the median PFS was 10.3 months (95% confidence interval, 6.1–14.5) and the median OS was 36.5 months. Except for one case not available for brain re-evaluation, control of the intracranial metastases was observed in 13 patients (13/14, 92.9%). No grade 4–5 adverse events (AEs) occurred, but all patients had grade 1–2 AEs, and 12.5% (4/32) patients required a dosage reduction due to intolerable AEs.

Conclusions: Dacomitinib demonstrated favorable activity with manageable toxicity in patients with NSCLC harboring major uncommon EGFR mutations.

Applications, Challenges, and Outlook for PBPK Modeling and Simulation: A Regulatory, Industrial and Academic Perspective

Several regulatory guidances on the use of physiologically based pharmacokinetic (PBPK) analyses and physiologically based biopharmaceutics model(s) (PBBM(s)) have been issued. Workshops are routinely held, demonstrating substantial interest in applying these modeling approaches to address scientific questions in drug development. PBPK models and PBBMs have remarkably contributed to model-informed drug development (MIDD) such as anticipating clinical PK outcomes affected by extrinsic and intrinsic factors in general and specific populations. In this review, we proposed practical considerations for a "base" PBPK model construction and development, summarized current status, challenges including model validation and gaps in system models, and future perspectives in PBPK evaluation to assess a) drug metabolizing enzyme(s)- or drug transporter(s)- mediated drug-drug interactions b) dosing regimen prediction, sampling timepoint selection and dose validation in pediatric patients from newborns to adolescents, c) drug exposure in patients with renal and/or and hepatic organ impairment, d) maternal-fetal drug disposition during pregnancy, and e) pH-mediated drug-drug interactions in patients treated with proton pump inhibitors/acid-reducing agents (PPIs/ARAs) intended for gastric protection. Since PBPK can simulate outcomes in clinical studies with enrollment challenges or ethical issues, the impact of PBPK models on waivers and how to strengthen study waiver is discussed.

First-in-human trial exploring safety, antitumor activity, and pharmacokinetics of Sym013, a recombinant pan-HER antibody mixture, in advanced epithelial malignancies

PURPOSE

 Sym013 contains six humanized monoclonal antibodies that bind to non-overlapping epitopes on three human epidermal growth factor receptors (HER1-3). Preclinical studies suggested Sym013 strongly suppresses growth of multiple epithelial tumors. This is a first-in-human study exploring safety and efficacy of Sym013 in patients with advanced epithelial malignancies.

METHODS

 Dose escalation used single-patient cohorts until the stopping rule was met, followed by 3 + 3 design. Dose levels planned were: 1, 2, 4, 6, 9, 12, 15, and 18 mg/kg. Treatment cycles were 28 days with imaging every eight weeks. Serum samples were collected at multiple time points for assessment of pharmacokinetics and development of anti-drug antibodies.

RESULTS

 Thirty-two patients were enrolled with multiple solid tumors, most common being colorectal cancer (CRC; 10/32, 31%). Due to mucositis, rash, and diarrhea at 4 mg/kg once-weekly, dosing was changed to biweekly (Q2W). Mandatory prophylaxis was added due to Grade 3 infusion-related reaction and oral mucositis at 9 mg/kg Q2W. The 15 mg/kg Q2W cohort was enrolling when the study was terminated for business reasons. Most common adverse events were skin (81%) and gastrointestinal (75%) disorders, including dermatitis/rash, stomatitis, and diarrhea. One patient with CRC achieved a partial response; 12 patients with varied malignancies had stable disease.

CONCLUSION

 During the conduct of the study, management of frequent infusion-related reactions, skin toxicities, and mucosal disorders, which are indicative of HER inhibition, necessitated multiple protocol amendments. The investigators, in concert with the Sponsor, agreed that achieving a tolerated regimen with acceptable target saturation was unlikely.

TRIAL REGISTRY

www.clinicaltrials.gov ; NCT02906670 (September 20, 2016).

EGFR Exon 20 Insertion Mutations in Sinonasal Squamous Cell Carcinoma

Recurrent epidermal growth factor receptor (EGFR)-activating mutations have been identified in a rare form of head and neck cancer known as sinonasal squamous cell carcinoma (SNSCC), a malignant disease with a 5-year mortality rate of ~40%. Interestingly, the majority of EGFR mutations identified in patients with primary SNSCC are exon 20 insertions (Ex20ins), which is in contrast to non-small-cell lung cancer (NSCLC), where the EGFR exon 19 deletion and L858R mutations predominate. These studies demonstrate that EGFR Ex20ins mutations are not exclusive to lung cancer as previously believed, but are also involved in driving SNSCC pathogenesis. Here we review the landscape of EGFR mutations in SNSCC, with a particular focus on SNSCC associated with inverted sinonasal papilloma (ISP), a benign epithelial neoplasm. Taking lessons from NSCLC, we also discuss potential new treatment options for ISP-associated SNSCC harbouring EGFR Ex20ins in the context of targeted therapies, drug resistance and precision cancer medicine. Moving forward, further basic and translational work is needed to delineate the biology of EGFR Ex20ins in SNSCC in order to develop more effective treatments for patients with this rare disease.

Effects of CYP2D6 Genetic Polymorphism and Drug Interaction on the Metabolism of Dacomitinib

We aim to study the effects of CYP2D6 variants and drug-drug interaction on the metabolism of dacomitinib. CYP2D6 variants were incubated with 25-1000 μM dacomitinib for 40 min at 37 °C, and the reaction was terminated by cooling to -80 °C immediately. For an in vivo experiment, 18 male Sprague-Dawley rats were randomly divided into three groups (n = 6): a single dose of 5 mg/kg dacomitinib (group A), a single dose of 6 mg/kg trazodone (group B), and a combined group (group C). Processed samples were analyzed by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS.) The relative clearance of dacomitinib was reduced for most of the variants. Moreover, the inhibitory potency of classic CYP inhibitors on dacomitinib metabolism was significantly different among the main subtypes of CYP2D6. Interestingly, compared with gefitinib, even the same CYP2D6 variants showed significant differences in metabolic activity, suggesting that the activity of CYP2D6 has strong variability. In addition, the interaction between trazodone and dacomitinib was determined both in vitro and in vivo. When dacomitinib was given in combination with trazodone, the blood exposure to these two drugs increased remarkably. The mechanistic study revealed that the interaction followed the noncompetitive inhibition. We demonstrated that the activity of CYP2D6 variants to metabolize dacomitinib was significantly reduced. In combination with the CYP2D6 inhibitor, the degree of activity inhibition of different variants obviously differed. When trazodone and dacomitinib were used in combination, the body exposure to the two drugs increased significantly. This study provides data for the precise use of dacomitinib in clinical settings.

EGFR-D770>GY and Other Rare EGFR Exon 20 Insertion Mutations with a G770 Equivalence Are Sensitive to Dacomitinib or Afatinib and Responsive to EGFR Exon 20 Insertion Mutant-Active Inhibitors in Preclinical Models and Clinical Scenarios

Epidermal growth factor receptor (EGFR) exon 20 insertion mutations account for a tenth of all EGFR mutations in lung cancers. An important unmet clinical need is the identification of EGFR exon 20 insertion mutants that can respond to multiple classes of approved EGFR-TKIs. We sought to characterize variants involving EGFR-D770 to EGFR-G770 position equivalence changes that structurally allow for response to irreversible 2nd generation EGFR-TKIs. Our group used preclinical models of EGFR exon 20 insertion mutations to probe representative 1st (erlotinib), 2nd (afatinib, dacomitinib), 3rd generation (osimertinib) and EGFR exon 20 insertion mutant-active (poziotinib, mobocertinib) TKIs; we also queried the available clinical literature plus our institutional database to enumerate clinical outcomes. EGFR-D770>GY and other EGFR insertions with a G770 equivalence were identified at a frequency of 3.96% in separate cohorts of EGFR exon 20 insertion mutated lung cancer (n = 429). Cells driven by EGFR-D770>GY were insensitive to erlotinib and osimertinib, displayed sensitivity to poziotinib and dacomitinib and were uniquely sensitive to afatinib and dacomitinib in comparison with other more typical EGFR exon 20 insertion mutations using proliferation and biochemical assays. Clinical cases with EGFR-G770 equivalence from the literature and our center mirrored the preclinical data, with radiographic responses and clinical benefits restricted to afatinib, dacomitinib, poziotinib and mobocertinib, but not to erlotinib or osimertinib. Although they are rare, at <4% of all exon 20 insertion mutations, EGFR-G770 equivalence exon 20 insertion mutations are sensitive to approved 2nd generation EGFR TKIs and EGFR exon 20 insertion mutant-active TKIs (mobocertinib and poziotinib). EGFR-D770>GY and other insertions with a G770 equivalence join EGFR-A763_Y764insFQEA as exon 20 insertion mutationsresponsive to approved EGFR TKIs beyond mobocertinib; this data should be considered for clinical care, genomic profiling reports and clinical trial elaboration.

HER2 Aberrations in Non-Small Cell Lung Cancer: From Pathophysiology to Targeted Therapy

While human epidermal growth factor receptor 2 (HER2) aberrations have long been described in patients with non-small cell lung cancer (NSCLC), they have only recently been effectively targeted. Unlike patients with breast cancer, NSCLC patients can harbor either HER2-activating mutations or HER2 amplification coupled with protein overexpression. The latter has also been the case for patients with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). As preclinical data continue to accumulate, clinical trials evaluating novel agents that target HER2 have produced promising preliminary results. Here, we review existing data on HER2 aberrations in NSCLC. Starting from HER2 biology in normal and disease processes, we summarize discrepancies in HER2 diagnostic assays between breast cancer and NSCLC. Finally, to dissect the therapeutic implications of HER2-activating mutations versus gene amplification and/or protein overexpression, we present data from prospective clinical trials that have employed distinct classes of agents to target HER2 in patients with NSCLC.

Efficacy of dacomitinib in patients with EGFR-mutated NSCLC and brain metastases

Background

Dacomitinib is a second‐generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) which is superior to first‐generation EGFR TKI in ARCHER 1050. However, the activity of dacomitinib in the central nervous system (CNS) is not known as ARCHER 1050 did not include patients with baseline brain metastases. This study aimed to describe dacomitinib's activity in the CNS in a real‐world setting.

Patients and Methods

Thirty‐two patients who were receiving dacomitinib for advanced non‐small‐cell lung cancer (NSCLC) with EGFR mutations and brain metastasis were included in this study. Patients who received prior EGFR TKIs were excluded from this trial. Case report forms were collected to determine treatment outcomes.

Results

Among 32 patients with EGFR‐mutated NSCLC and brain disease, eight were included in the CNS evaluable for response group. The intracranial objective response rate (iORR) was 87.5% (95% confidence interval [CI] 47.3–99.7%) and the intracranial disease control rate (iDCR) was 100% (95% CI 63.1–100%). In 30 evaluable patients with measurable or nonmeasurable brain lesions, the iORR was 66.7% (95% CI 47.2–82.7%) and the iDCR was 100% (95% CI 88.4–100%). Median intracranial duration of response (iDoR) and intracranial progression‐free survival (iPFS) were not reached, with a one‐year iDoR rate of 72.2% (95% CI 48.7–95.7%) and a 1‐year iPFS rate of 71.2% (95% CI 51.0–91.4%), respectively. The majority of patients experienced low‐grade (G1/2) toxicities, which are reversible.

Conclusion

This study suggests that dacomitinib demonstrated CNS efficacy in patients with EGFR TKI‐naïve EGFR‐mutated NSCLC in the real‐world setting. The safety profile was tolerable and manageable.

In vitro validation study of HER2 and HER4 mutations identified in an ad hoc secondary analysis of the LUX-Lung 8 randomized clinical trial

OBJECTIVES

The LUX-Lung 8 randomized trial (LL8) demonstrated a prolonged progression-free survival (PFS) in patients with metastatic squamous cell carcinoma (SCC) of the lung after treatment with afatinib compared with erlotinib. A secondary analysis of the LL8 reported that the presence of rare HER2/HER4 mutations may be partly responsible for this result. Patients with HER2 (hazard ratio [HR] 0.06/p-value 0.02) or HER4 (HR 0.21/p-value unreported) mutations had longer PFS after treatment with afatinib. However, the biological function of these mutations is unclear.

MATERIALS AND METHODS

Ten HER2 and 13 HER4 point mutations that were detected in the secondary analysis were transduced into the mouse pro-B cell line (Ba/F3) to determine changes in interleukin-3 (IL-3) dependence and sensitivity to six EGFR or pan-HER tyrosine kinase inhibitors (TKIs), including afatinib and erlotinib. The efficacy of the six TKIs was compared using a sensitivity index, defined as the 50% inhibitory concentration divided by trough concentration of each drug at clinically recommended doses.

RESULTS

Seven out of 10 Ba/F3 clones expressing HER2 mutations and all 13 Ba/F3 clones expressing HER4 mutations did not grow in the absence of IL-3, indicating these mutations were non-oncogenic. Three Ba/F3 clones expressing the HER2 mutations E395K, G815R, or R929W acquired IL-3-independent growth. The sensitivity indices for afatinib were ≤ one-fifth of those for erlotinib in all three lines. Other second/third-generation (2G/3G) TKIs showed high efficacy against clones expressing these HER2 mutations.

CONCLUSIONS

The majority of HER2/4 mutations detected in lung SCC from LL8 were not oncogenic in the Ba/F3 models, suggesting that the presence of HER2/4 mutations were not responsible for the superior outcomes of afatinib in the LL8 study. However, SCC of the lung in some patients may be driven by rare HER2 mutations, and these patients may benefit from 2G/3G pan-HER-TKI treatment.

Simultaneous determination of dacomitinib and its major metabolite, O-desmethyl dacomitinib in human plasma by LC-MS/MS and its application to clinical testing in patients with non-small cell lung cancer

Dacomitinib, an irreversible pan-ErbB tyrosine kinase inhibitor targeting the human epidermal growth factor receptor, is used for the treatment of metastatic non-small cell lung cancer. To facilitate the investigations on its metabolism and other relevant studies, based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a rapid and sensitive bioanalytical technique was established and fully validated for simultaneous quantification of dacomitinib and its main metabolite in human plasma. The plasma samples were treated with acetonitrile containing 0.1% formic acid and the liquid supernatant was collected, dried and dissolved in methanol-water-formic acid (200:800:1, v/v) before injection. The chromatographic separation was performed on an ACE Excel C₁₈ column (2.1 mm × 50.0 mm, i.d., 5 μm) by gradient elution with a mixture of buffer (5 mM ammonium acetate in 0.1% formic acid) and acetonitrile, serving as the mobile phase, with an overall run time of 4 min. Dacomitinib, O-desmethyl dacomitinib and IS were subsequently detected on an AB QTRAP 5500 mass spectrometer in positive ion and multiple reaction monitoring modes at the precursor-to-product transitions of m/z 470.4 → 385.0, m/z 456.0 → 370.9 and m/z 480.2 → 385.1, respectively. The accuracy and precision of determinations were guaranteed within the concentration ranges of 0.25-100 ng/mL for dacomitinib and 0.20-80 ng/mL for O-desmethyl dacomitinib. The intra- and inter-assay accuracy ranged from 92.00% to 104.50% and the intra- and inter-assay precision was less than 8.20% for each analyte. The method was validated and the relevant parameters, including selectivity, interference among analytes and internal standard, carry-over effect, dilution integrity, extraction recovery, matrix effect, and stability, all satisfied the requirements formulated by the US Food and Drug Administration and the European Medicines Agency. The clinical applicability of the fully-validated method was evaluated in medicated samples from patients on dacomitinib.

Targeting the Epidermal Growth Factor Receptor in EGFR-Mutated Lung Cancer: Current and Emerging Therapies

Epidermal growth factor receptor-targeting tyrosine kinase inhibitors (EGFR TKIs) are the standard of care for patients with EGFR-mutated metastatic lung cancer. While EGFR TKIs have initially high response rates, inherent and acquired resistance constitute a major challenge to the longitudinal treatment. Ongoing work is aimed at understanding the molecular basis of these resistance mechanisms, with exciting new studies evaluating novel agents and combination therapies to improve control of tumors with all forms of EGFR mutation. In this review, we first provide a discussion of EGFR-mutated lung cancer and the efficacy of available EGFR TKIs in the clinical setting against both common and rare EGFR mutations. Second, we discuss common resistance mechanisms that lead to therapy failure during treatment with EGFR TKIs. Third, we review novel approaches aimed at improving outcomes and overcoming resistance to EGFR TKIs. Finally, we highlight recent breakthroughs in the use of EGFR TKIs in non-metastatic EGFR-mutated lung cancer.

Identification of optimal dosing schedules of dacomitinib and osimertinib for a phase I/II trial in advanced EGFR-mutant non-small cell lung cancer

Despite the clinical success of the third-generation EGFR inhibitor osimertinib as a first-line treatment of EGFR-mutant non-small cell lung cancer (NSCLC), resistance arises due to the acquisition of EGFR second-site mutations and other mechanisms, which necessitates alternative therapies. Dacomitinib, a pan-HER inhibitor, is approved for first-line treatment and results in different acquired EGFR mutations than osimertinib that mediate on-target resistance. A combination of osimertinib and dacomitinib could therefore induce more durable responses by preventing the emergence of resistance. Here we present an integrated computational modeling and experimental approach to identify an optimal dosing schedule for osimertinib and dacomitinib combination therapy. We developed a predictive model that encompasses tumor heterogeneity and inter-subject pharmacokinetic variability to predict tumor evolution under different dosing schedules, parameterized using in vitro dose-response data. This model was validated using cell line data and used to identify an optimal combination dosing schedule. Our schedule was subsequently confirmed tolerable in an ongoing dose-escalation phase I clinical trial (NCT03810807), with some dose modifications, demonstrating that our rational modeling approach can be used to identify appropriate dosing for combination therapy in the clinical setting.

Olmutinib in T790M-positive non-small cell lung cancer after failure of first-line epidermal growth factor receptor-tyrosine kinase inhibitor therapy: A global, phase 2 study

Background

In this open‐label, international phase 2 study, the authors assessed the efficacy and safety of olmutinib in patients with locally advanced or metastatic non–small cell lung cancer (NSCLC) who had a confirmed T790M mutation and disease progression on previous epidermal growth factor receptor‐tyrosine kinase inhibitor therapy.

Methods

Patients aged ≥20 years received once‐daily oral olmutinib 800 mg continuously in 21‐day cycles. The primary endpoint was the objective response rate (patients who had a confirmed best overall response of a complete or partial response), assessed by central review. Secondary endpoints included the disease control rate, the duration of objective response, progression‐free survival, and overall survival. Adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 4.03).

Results

Overall, 162 patients (median age, 63 years; women, >60%) were enrolled from 68 sites in 9 countries. At the time of database cutoff, 23.5% of enrolled patients remained on treatment. The median treatment duration was 6.5 months (range, 0.03‐21.68 months). Overall, 46.3% of patients (95% CI, 38.4%‐54.3%) had a confirmed objective response (all partial responses). The best overall response (the objective response rate regardless of confirmation) was 51.9% (84 patients; 95% CI, 43.9%‐59.8%). The confirmed disease control rate for all patients was 86.4% (95% CI, 80.2%‐91.3%). The median duration of objective response was 12.7 months (95% CI, 8.3‐15.4 months). Estimated median progression‐free survival was 9.4 months (95% CI, 6.9‐12.3 months), and estimated median overall survival was 19.7 months (95% CI, 15.1 months to not reached). All patients experienced treatment‐emergent adverse events, and 71.6% of patients had grade ≥3 treatment‐emergent adverse events.

Conclusions

Olmutinib has meaningful clinical activity and a manageable safety profile in patients with T790M‐positive non–small cell lung cancer who received previous epidermal growth factor receptor‐tyrosine kinase inhibitor therapy.

Olmutinib (HM61713) is a third‐generation, mutation‐specific epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that targets mutant‐type EGFR and has minimal activity against wild‐type EGFR. This open‐label, international phase 2 study demonstrates the efficacy and safety of oral olmutinib 800 mg once daily in patients with locally advanced or metastatic non–small cell lung cancer who have a confirmed T790M mutation and disease progression on previous EGFR tyrosine kinase inhibitor therapy.

Osimertinib for Chinese advanced non-small cell lung cancer patients harboring diverse EGFR exon 20 insertion mutations

OBJECTIVES

Epidermal growth factor receptor (EGFR) exon 20 insertion (ex20 ins) mutations are generally associated with de novo resistance to first- or second-generation EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). However, the real efficacy of osimertinib for this subset remains elusive. We performed this study to investigate the real efficacy of osimertinib for Chinese advanced NSCLC patients harboring EGFR ex20 ins mutations.

MATERIALS AND METHODS

We retrospectively collected data of metastatic NSCLC patients with EGFR ex20 ins mutations who were treated with osimertinib 80 mg or 160 mg once daily in our center from June 2017 to May 2020. Progression-free survival (PFS), objective response rate (ORR) and disease control rate (DCR) were assessed.

RESULTS

A total of 62 cases with EGFR ex20 ins mutations were included, and the major insertion variant was D770_N771insSVD and V769_D770insASV (45.1 %). Concurrent TP53 mutation was most commonly observed (59.7 %). Four patients showed partial response, 29 cases with stable disease and 29 showed progressive disease as best response to osimertinib (ORR: 6.5 %, DCR: 53.2 %). The median PFS (mPFS) in total patients was 2.3 (95 %CI, 1.5-3.1) months. Patients harboring A763_Y764insFQEA/D770delinsGY variants showed numerically longer mPFS than those with other variants (4.2 vs. 2.2 months, P =  0.164). Patients who failed to osimertinib and occurred extracranial progression showed similar mPFS to those with intracranial progression (2.3 vs. 1.9 months, P =  0.142). Median PFS was not significantly different between patients who received osimertinib 80mg or 160mg once daily (2.5 vs. 1.3 months, P = 0.161), either with no significance when it used in fist-line setteing or bove (3.0 vs. 2.2 months, P =  0.639).

CONCLUSION

The unique insertion variant A763_Y764insFQEA and D770delinsGY might better respond to osimertinib than other ex20 ins subtypes. Osimertinib either 80 mg or 160 mg once daily showed less activity in Chinese NSCLC patients harboring diverse EGFR ex20 ins mutations.

Genotype Driven Therapy for Non-Small Cell Lung Cancer: Resistance, Pan Inhibitors and Immunotherapy

Eighty-five percent of patients with lung cancer present with Non-small Cell Lung Cancer (NSCLC). Targeted therapy approaches are promising treatments for lung cancer. However, despite the development of targeted therapies using Tyrosine Kinase Inhibitors (TKI) as well as monoclonal antibodies, the five-year relative survival rate for lung cancer patients is still only 18%, and patients inevitably become resistant to therapy. Mutations in Kirsten Ras Sarcoma viral homolog (KRAS) and epidermal growth factor receptor (EGFR) are the two most common genetic events in lung adenocarcinoma; they account for 25% and 20% of cases, respectively. Anaplastic Lymphoma Kinase (ALK) is a transmembrane receptor tyrosine kinase, and ALK rearrangements are responsible for 3-7% of NSCLC, predominantly of the adenocarcinoma subtype, and occur in a mutually exclusive manner with KRAS and EGFR mutations. Among drug-resistant NSCLC patients, nearly half exhibit the T790M mutation in exon 20 of EGFR. This review focuses on some basic aspects of molecules involved in NSCLC, the development of resistance to treatments in NSCLC, and advances in lung cancer therapy in the past ten years. Some recent developments such as PD-1-PD-L1 checkpoint-based immunotherapy for NSCLC are also covered.

Response to Afatinib in a Patient with NSCLC Harboring Novel EGFR Exon 20 Insertion Mutations

Purpose

Most epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations are resistant to tyrosine kinase inhibitors (TKIs). While some non-small cell lung cancer (NSCLC) patients harboring special subtypes of EGFR ex20ins still achieved clinical response after TKIs treatment, identifying special subtypes of EGFR ex20ins is helpful to find out NSCLC patients who can respond to TKIs.

Case Presentation

A 71-year-old non-smoker Chinese female was diagnosed with advanced lung adenocarcinoma harboring EGFR ex20ins (N771delinsKG). The patient received first-line afatinib (40 mg/day) therapy and a significant and substantial reduction in tumor size was observed subsequently. According to RESIST 1.1, a radiological partial response was achieved. The final progression-free survival was 10 months.

Conclusion

This is the first published case report of EGFR N771delinsKG lung adenocarcinoma, which highlighted the heterogeneity of clinical response to TKIs for EGFR ex20ins-mutant NSCLC. Such results need to be further investigated in prospective studies.

Poor effect of osimertinib on EGFR exon 20 insertion-positive lung adenocarcinoma: A case report

INTRODUCTION

The clinical efficacy of osimertinib for patients with lung adenocarcinoma harboring epidermal growth factor receptor (EGFR) exon 20 insertion mutations is unclear. Few case reports exist on the successful treatment of such tumors with osimertinib. We report a case wherein osimertinib administration had no effect in a patient with EGFR exon 20 insertion-positive lung adenocarcinoma.

PATIENT CONCERNS

A 48-year-old never-smoking woman was referred to our hospital for chronic cough. Computed tomography (CT) and positron emission tomography-CT revealed a nodule in the right middle lobe, consolidation in the right upper lobe, multiple lymph node metastases, liver metastasis, and multiple bone metastases.

DIAGNOSIS

On the basis of further examination using transbronchial lung biopsy, the patient was diagnosed with cT1N3M1 stage IVB lung adenocarcinoma. An EGFR exon 20 insertion, without any additional mutations, was identified.

INTERVENTIONS

Daily oral administration of 80 mg osimertinib was initiated to treat the EGFR exon 20 insertion-positive lung adenocarcinoma.

OUTCOMES

Although the disease appeared to be stable 2.5 months after the administration of osimertinib, the tumor started to grow 3 months after administration, and carcinoembryonic antigen levels became higher than those before treatment. Thus, osimertinib was discontinued, and treatment with carboplatin as well as pemetrexed and bevacizumab was started, which the patient responded to.

CONCLUSION

EGFR exon 20 insertion mutations must be classified in more detail to assess the efficacy of EGFR tyrosine kinase inhibitors. Osimertinib doses that provide favorable therapeutic windows should be considered. Further clinical research is required to clarify the efficacy of osimertinib and other drugs for exon 20 insertion mutations.

Exploring Predictors of Response to Dacomitinib in EGFR-Amplified Recurrent Glioblastoma

PURPOSE

Despite the high frequency of EGFR genetic alterations in glioblastoma (GBM), EGFR-targeted therapies have not had success in this disease. To improve the likelihood of efficacy, we targeted adult patients with recurrent GBM enriched for EGFR gene amplification, which occurs in approximately half of GBM, with dacomitinib, a second-generation, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that penetrates the blood-brain barrier, in a multicenter phase II trial.

PATIENTS AND METHODS

We retrospectively explored whether previously described EGFR extracellular domain (ECD)-sensitizing mutations in the context of EGFR gene amplification could predict response to dacomitinib, and in a predefined subset of patients, we measured post-treatment intratumoral dacomitinib levels to verify tumor penetration.

RESULTS

We found that dacomitinib effectively penetrates contrast-enhancing GBM tumors. Among all 56 treated patients, 8 (14.3%) had a clinical benefit as defined by a duration of treatment of at least 6 months, of whom 5 (8.9%) remained progression free for at least 1 year. Presence of EGFRvIII or EGFR ECD missense mutation was not associated with clinical benefit. We evaluated the pretreatment transcriptome in circulating extracellular vesicles (EVs) by RNA sequencing in a subset of patients and identified a signature that distinguished patients who had durable benefit versus those with rapid progression.

CONCLUSION

While dacomitinib was not effective in most patients with EGFR-amplified GBM, a subset experienced a durable, clinically meaningful benefit. Moreover, EGFRvIII and EGFR ECD mutation status in archival tumors did not predict clinical benefit. RNA signatures in circulating EVs may warrant investigation as biomarkers of dacomitinib efficacy in GBM.

Is there a role for dacomitinib, a second-generation irreversible inhibitor of the epidermal-growth factor receptor tyrosine kinase, in advanced non-small cell lung cancer?

INTRODUCTION

Non-small cell lung cancer (NSCLC) is a highly lethal disease. During the past 20 years, the epidermal growth factor receptor (EGFR) has been a relevant target for anticancer drug-design, and a large family of EGFR tyrosine kinase inhibitors (TKI) were designed, which improved therapeutic outcomes compared to conventional chemotherapy in NSCLC patients with specific EGFR mutations. However, resistance to these inhibitors occurs; therefore, the debate on which inhibitor should be used first is still open. Dacomitinib was approved in 2018 for the first-line treatment of NSCLC with EGFR activating mutations.

AREAS COVERED

This manuscript reviews the properties of dacomitinib, including the current information from clinical trials and its potential application as stand-alone therapy, or in combination.

EXPERT OPINION

Dacomitinib is a second-generation EGFR-TKI that has demonstrated significant improvement in overall survival in a phase III randomized study compared with gefitinib, a first-generation TKI. However, the rapid development and approval of a new generation of TKIs (osimertinib), with better clinical profiles, raises the question of which role can dacomitinib play in NSCLC. Further studies are required to evaluate the efficacy of this drug on brain metastases, as a second-line treatment after third-generation TKIs, or in combination with other types of treatments.

EGFR exon 20 insertion mutations in non-small cell lung cancer

Mutations in the epidermal growth factor receptor (EGFR) gene are the most common targetable genomic drivers of non-small cell lung cancer (NSCLC). 90% of the EGFR mutations comprise of EGFR exon 19 deletion and exon 21 L858R mutation, while EGFR exon 20 insertion (EGFR Ex20Ins) is the third most common type of EGFR mutation. Currently, studies on EGFR Ex20Ins are relatively scarce and limited. The frequency of EGFR Ex20Ins mutations in NSCLC was 1–10%. Patients harboring EGFR Ex20Ins exhibited similar clinical characteristics except for poorer prognosis as compared to patients with sensitizing mutations in EGFR. Conventional TKIs have poor efficacy in a majority of EGFR Ex20Ins subtypes. Chemotherapy remains the preferred treatment for advanced NSCLC patients harboring EGFR Ex20Ins. However, some novel inhibitors are considered as putative candidates. This review focuses on the structural and biochemical features, clinical characteristics, treatments, and prognosis of EGFR Ex20Ins in NSCLC.

Rare epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) mutations are the second most common oncogenic driver event in non-small cell lung cancer (NSCLC). Classical activating mutations (exon 19 deletions and the L858R point mutation) comprise the vast majority of EGFR mutations and are well defined as strong predictors for good clinical response to EGFR tyrosine kinase inhibitors (EGFRi). However, low frequency mutations including point mutations, deletions, insertions and duplications occur within exons 18-25 of the EGFR gene in NSCLC and are associated with poorer responses to EGFRi. Despite an increased uptake of more sensitive detection methods to identify rare EGFR mutations in patients, our understanding of the biology of these rare EGFR mutations is poor compared to classical mutations. In particular, clinical data focused on these mutations is lacking due to their rarity and challenges in trial recruitment, resulting in an absence of effective treatment strategies for many low frequency EGFR mutations. In this review, we describe the structural and mechanistic features of rare EGFR mutations in NSCLC and discuss the preclinical and clinical evidence for EGFRi response for individual rare EGFR mutations. We also discuss EGFRi sensitivity for complex EGFR mutations, and conclude by offering a perspective on the outstanding questions and future steps required to make advances in the treatment of NSCLC patients that harbour rare EGFR mutations.

HER2 exon 20 insertions in non-small-cell lung cancer are sensitive to the irreversible pan-HER receptor tyrosine kinase inhibitor pyrotinib

BACKGROUND

Effective targeted therapy for non-small-cell lung cancer (NSCLC) patients with human epidermal growth factor receptor 2 (HER2) mutations remains an unmet need. This study investigated the antitumor effect of an irreversible pan-HER receptor tyrosine kinase inhibitor, pyrotinib.

PATIENTS AND METHODS

Using patient-derived organoids and xenografts established from an HER2-A775_G776YVMA-inserted advanced lung adenocarcinoma patient sample, we investigated the antitumor activity of pyrotinib. Preliminary safety and efficacy of pyrotinib in 15 HER2-mutant NSCLC patients in a phase II clinical trial are also presented.

RESULTS

Pyrotinib showed significant growth inhibition of organoids relative to afatinib in vitro (P = 0.0038). In the PDX model, pyrotinib showed a superior antitumor effect than afatinib (P = 0.0471) and T-DM1 (P = 0.0138). Mice treated with pyrotinib displayed significant tumor burden reduction (mean tumor volume, -52.2%). In contrast, afatinib (25.4%) and T-DM1 (10.9%) showed no obvious reduction. Moreover, pyrotinib showed a robust ability to inhibit pHER2, pERK and pAkt. In the phase II cohort of 15 patients with HER2-mutant NSCLC, pyrotinib 400 mg resulted in a objective response rate of 53.3% and a median progression-free survival of 6.4 months.

CONCLUSION

Pyrotinib showed activity against NSCLC with HER2 exon 20 mutations in both patient-derived organoids and a PDX model. In the clinical trial, pyrotinib showed promising efficacy.

CLINICAL TRIAL REGISTRATION

NCT02535507.

Phase 1 study of the pan-HER inhibitor dacomitinib plus the MEK1/2 inhibitor PD-0325901 in patients with KRAS-mutation-positive colorectal, non-small-cell lung and pancreatic cancer

Background

Mutations in KRAS result in a constitutively activated MAPK pathway. In KRAS-mutant tumours existing treatment options, e.g. MEK inhibition, have limited efficacy due to resistance through feedback activation of epidermal growth factor receptors (HER).

Methods

In this Phase 1 study, the pan-HER inhibitor dacomitinib was combined with the MEK1/2 inhibitor PD-0325901 in patients with KRAS-mutant colorectal, pancreatic and non-small-cell lung cancer (NSCLC). Patients received escalating oral doses of once daily dacomitinib and twice daily PD-0325901 to determine the recommended Phase 2 dose (RP2D). (Clinicaltrials.gov: NCT02039336).

Results

Eight out of 41 evaluable patients (27 colorectal cancer, 11 NSCLC and 3 pancreatic cancer) among 8 dose levels experienced dose-limiting toxicities. The RP2D with continuous dacomitinib dosing was 15 mg of dacomitinib plus 6 mg of PD-0325901 (21 days on/7 days off), but major toxicity, including rash (85%), diarrhoea (88%) and nausea (63%), precluded long-term treatment. Therefore, other intermittent schedules were explored, which only slightly improved toxicity. Tumour regression was seen in eight patients with the longest treatment duration (median 102 days) in NSCLC.

Conclusions

Although preliminary signs of antitumour activity in NSCLC were seen, we do not recommend further exploration of this combination in KRAS-mutant patients due to its negative safety profile.

[Studies and Progress of EGFR exon 20 Insertion Mutation in Non-small Cell Lung Cancer]

Lung cancer has the highest morbidity and mortality among malignant tumors worldwidely. Targeted therapy related to non-small cell lung cancer (NSCLC) is the research hotspot in recent year. The emergence of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) has brought a huge change in the treatment of patients with EGFR mutation. The patients with EGFR exon20 insertion are specific cohort in NSCLC. Reviewing the clinical researches to EGFR exon20 insertion mutation positive NSCLC, as well as summarizing character, testing methods and treatment, will provide a help for clinical application, bringing more benefits for patients at the same time.

Novel drugs targeting EGFR and HER2 exon 20 mutations in metastatic NSCLC

Approximately 4% of epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) present EGFR exon 20 in-frame insertions, accounting for 0.3 %-3.7 % of NSCLC. In addition, 2 %-4 % of patients with NSCLC harbor human epidermal growth factor receptor 2 gene (HER2) mutations, being the 90 % of them exon 20 insertions. These mutations confer intrinsic resistance to available EGFR tyrosine kinase inhibitors (TKIs) and anti-HER2 treatments, as they result in steric hindrance of the drug-binding pocket. Therefore, no targeted therapies have been approved for NSCLC patients with EGFR or HER2 exon 20- activating mutations to date and remain an unmet clinical need. Promising efforts to novel treatment development have been made. Early data provide encouraging activity of novel drugs targeting EGFR and HER2 mutations in metastatic NSCLC. In this review we will summarize all the data reported to date about these driver molecular alterations and potential targeted therapies.

Evaluation of the potential effect of dacomitinib, an EGFR tyrosine kinase inhibitor, on ECG parameters in patients with advanced non-small cell lung cancer

Purpose The study evaluated the potential effect of dacomitinib, a small molecule epidermal growth factor receptor (EGFR) inhibitor, on the electrocardiogram (ECG) parameters in adult patients with advanced non-small cell lung cancer enrolled in a multicenter, open-label, phase 2 study. Methods Patients received dacomitinib for six doses of 45 mg every 12 h in a 7-day lead-in cycle (cycle 0), then 60 mg every 12 h for six doses in a 14-day cycle (cycle 1). Clock time-matched triplicate ECGs were performed at 0, 2, 4, 6, 8 and 10 h on day 1 (baseline) and day 4 of cycle 0, and prior to dose on days 1 and 4 of cycle 1. The QT interval was corrected for heart rate using Fridericia's correction (QTcF) and a study specific correction factor (QTcS). Results Thirty-two patients in the study comprised the QTc-evaluable population. Dacomitinib had no effect on the heart rate. The upper limits of the 95% confidence interval (CI) for the mean change from baseline in QTcF and QTcS were < 10 ms at all time points. A lack of relationship between plasma concentrations of dacomitinib or total active moiety on QTcF and QTcS was evidenced. All upper 90% CIs of the PR intervals were < 200 ms, although a small mean increase from baseline (2.7-6.6 ms) was observed. Conclusions There was a lack of a clinically relevant effect of dacomitinib on ECG parameters at dacomitinib concentrations comparable to those obtained at its highest therapeutic dosing regimen of 45 mg once daily. ClinicalTrials.gov identifier: NCT01858389.

Clinical evaluation of dacomitinib for the treatment of metastatic non-small cell lung cancer (NSCLC): current perspectives

Systemic treatment of advanced non-small cell lung cancer (NSCLC) has undergone remarkable changes in the last decade, with the introduction of targeted therapies and immunotherapy. The identification of activating mutations in the epidermal growth factor receptor (EGFR) gene (deletions in exon 19 [Del19] and point mutation L858R in exon 21) has been the first important step toward molecularly guided precision therapy in lung cancer. Several randomized trials comparing EGFR tyrosine kinase inhibitors (TKIs) (gefitinib, erlotinib, and afatinib) to standard chemotherapy in first-line treatment of advanced EGFR-mutant NSCLC showed significant improvement in progression-free survival (PFS) and in response rate, with lower rates of adverse events (AEs) and better symptom control. However, none of these trials showed significant improvement in overall survival (OS). Despite impressive responses with EGFR-TKI, disease invariably progresses after 9 to 13 months, due to acquired resistance. Dacomitinib is a potent, irreversible, highly selective, second-generation EGFR-TKI, which inhibits the signaling from both heterodimers and homodimers of all the members of the human epidermal growth factor receptor (HER) family. Here, we review the clinical development of dacomitinib from phase I to phase III, with particular attention to its toxicity and on its activity on T790M mutation. Then, we critically examine the results of ARCHER 1050, a study that was crucial for Food and Drug Administration (FDA) approval. ARCHER 1050 was the first randomized phase III study comparing dacomitinib with gefitinib, in first-line treatment of patients with advanced EGFR-mutated NSCLC. Dacomitinib was superior to gefitinib in terms of primary end-point (14.7 vs 9.2 months) and OS (34.1 vs 26.8 months). The incidence of diarrhea, skin rash, mucositis and, consequently, dose reductions was higher with dacomitinib, while hepatic toxicity was higher with gefitinib. Dacomitinib constitutes one of the standard first-line options in patients with advanced EGFR-mutated NSCLC.

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Dacomitinib in non-small-cell lung cancer: a comprehensive review for clinical application

Dacomitinib is a second-generation EGFR tyrosine kinase inhibitor (TKI) that irreversibly binds to and inhibits EGFR/Her1, Her2 and Her4 subtypes with an efficacy comparable to other TKIs. In the ARCHER 1050 trial, progression-free survival was improved by dacomitinib compared with gefitinib, supporting dacomitinib as a first-line treatment option for advanced non-small-cell lung cancer with sensitive EGFR mutation. Regarding to the higher adverse events rate, dose reductions did not reduce the efficacy of dacomitinib and could effectively decreased the incidence and severity of adverse events. Considering the evolving landscape of EGFR-mutant non-small-cell lung cancer, future head to head comparison between dacomitinib and osimertinib could provide key information to determine the optimal TKI treatment schedule.

Dacomitinib for the first-line treatment of patients with EGFR-mutated metastatic non-small cell lung cancer

Introduction: Different EGFR tyrosine kinase inhibitors (TKIs) are currently approved for the first-line treatment of NSCLC patients with EGFR mutations. Dacomitinib is an orally administered, second-generation pan-HER inhibitor that has shown to improve PFS and OS compared to the first-generation TKI gefitinib and is the most recent inhibitor to be approved in this setting. Areas covered: This article will review relevant literature regarding preclinical findings and clinical data from phase I-III trials of dacomitinib. We particularly discuss the mechanism of action of dacomitinib and its clinical efficacy and toxicity as a novel, first-line therapeutic option for EGFR-mutated NSCLC. Expert commentary: The therapeutic landscape for EGFR-mutated NSCLC has been greatly expanded. In the first-line setting, we have currently first-, second- and third-generation EGFR TKIs available and some combination strategies, including EGFR TKIs with anti-angiogenic drugs or chemotherapy, have also shown to be effective. However, more data are needed to define the optimal therapeutic sequencing of all these targeted agents and combinations. In this view, molecular profiling of tumor tissues and liquid biopsies may provide novel insights on mechanisms of resistance to different drugs and guide treatment decisions.

Dacomitinib in the Management of Advanced Non-Small-Cell Lung Cancer

The use of targeted therapy in the management of epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer is an important milestone in the management of advanced lung cancer. There are several generations of EGFR tyrosine kinase inhibitors available for clinical use. Dacomitinib is a second-generation irreversible EGFR tyrosine kinase inhibitor with early-phase clinical studies showing efficacy in non-small-cell lung cancer. In the recently published ARCHER 1050 phase III study, dacomitinib given at 45 mg/day orally was superior to gefitinib, a first-generation reversible EGFR tyrosine kinase inhibitor, in improving both progression-free survival and overall survival when given as first-line therapy. There is no prospective evidence to support the use of dacomitinib as subsequent therapy in patients previously treated with chemotherapy or a first-generation EGFR tyrosine kinase inhibitor such as gefitinib and erlotinib. Dacomitinib has not demonstrated any benefit in unselected patients with non-small-cell lung cancer, and its use should be limited to those with known EGFR-sensitizing mutations. Dacomitinib is associated with increased toxicities of diarrhea, rash, stomatitis, and paronychia compared with first-generation EGFR inhibitors. Global quality of life was maintained when assessed in phase III studies. Overall, dacomitinib is an important first- line agent in EGFR-mutated non-small-cell lung cancer in otherwise fit patients whose toxicities can be well managed.

Safety, tolerability, and anti-tumor activity of olmutinib in non-small cell lung cancer with T790M mutation: A single arm, open label, phase 1/2 trial

OBJECTIVES

The aim of this phase 1/2 study was to evaluate the safety, tolerability, pharmacokinetics and antitumor activity of olmutinib in patients with epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) who had failed ≥ 1 previous line of EGFR-tyrosine kinase inhibitor (TKI) therapy.

MATERIALS AND METHODS

Phase 1 consisted of dose-escalation and four dose-expansion parts (1: olmutinib 300 mg once daily; 2A: 800 mg once daily [EGFR T790 M mutation-positive patients]; 2B: 500 mg twice daily [EGFR T790 M mutation-positive]; 3: 800 mg once daily [EGFR T790 M mutation-negative]). In phase 2, EGFR T790 M mutation-positive patients received olmutinib 800 mg once daily. Data from expansion part 2A and phase 2 were integrated (`pooled phase 2'). Each olmutinib cycle was 21 days. Outcomes included: tumor response, treatment-emergent adverse events (TEAEs), pharmacokinetic parameters.

RESULTS

Overall, 272 patients received at least one olmutinib dose: dose-escalation (n = 66), expansion parts (n = 165), phase 2 (n = 41). In pooled phase 2, the overall objective response rate, confirmed by independent review, was 55.1% (38/69 evaluable patients; 95% CI, 42.6-67.1). All responses were partial responses; 23 patients had stable disease. Estimated median progression-free survival was 6.9 (95% CI, 5.6-9.7) months; estimated median overall survival was not reached. The most frequent treatment-related AEs were diarrhea (59.2% of patients), pruritus (42.1%), rash (40.8%), and nausea (39.5%).

CONCLUSION

Olmutinib showed effective clinical activity with a manageable safety profile, indicating therapeutic potential for T790M-positive NSCLC patients who have failed ≥ 1 previous line of EGFR-TKI therapy.

Targeting EGFR exon 20 insertion mutations in non-small cell lung cancer

Inframe insertions of three or more base pairs in exon 20 of the epidermal growth factor receptor (EGFR) gene were among the first EGFR mutations to be identified as oncogenic drivers in non-small cell lung cancer (NSCLC). However, unlike the classical EGFR L858R point mutation or exon 19 deletions, which represent the majority of EGFR mutations in NSCLC, low frequency EGFR exon 20 insertion mutations are associated with de novo resistance to targeted EGFR inhibitors and correlate with a poor patient prognosis. Here, we review the developments over the last 5 years in which pre-clinical studies, including elucidation of the crystal structure of an EGFR exon 20 insertion mutant kinase, have revealed a unique mechanism of kinase activation and steric conformation that define the lack of response of these EGFR mutations to clinically approved EGFR inhibitors. The recent development of several novel small molecule compounds that selectively inhibit EGFR exon 20 insertions holds promise for future therapeutic options that will be effective for patients with this molecular subtype of NSCLC.

EGFR first- and second-generation TKIs-there is still place for them in EGFR-mutant NSCLC patients

Identification of epidermal growth factor receptor (EGFR) as a molecular target has radically changed the treatment of metastatic non-small cell lung cancer (NSCLC) from standard chemotherapy to personalized, targeted therapy. First-, second- and third-generation EGFR tyrosine kinase inhibitors (TKIs) are now available for the treatment of EGFR-mutant NSCLC patients. This review will focus on the clinical development of first- and second-generation EGFR TKIs. We will emphasize on essential points like the head-to-head comparison among EGFR TKIs, their activity on brain metastases, mechanisms of resistance, as well as their combination with anti-angiogenic compounds, other targeted therapies, or immunotherapy. The efficacy of first- and second-generation EGFR TKIs in early-stage EGFR-mutant NSCLC will be also finally reviewed.

Quantitative bioanalytical assay for the human epidermal growth factor receptor (HER) inhibitor dacomitinib in rat plasma by UPLC-MS/MS

Dacomitinib is a highly selective irreversible small-molecule inhibitor of the human epidermal growth factor receptor (HER) family of tyrosine kinases. A simple and quick bioanalytical method was completely developed and validated for the assay and pharmacokinetic investigation of dacomitinib in rat plasma using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Proteins in 0.1 mL plasma samples were prepared by precipitant acetonitrile containing ibrutinib as the internal standard (IS). Separation of the analyte from plasma samples was carried out on an Acquity UPLC BEH C18 column using acetonitrile and 0.1% formic acid in water as mobile phase for gradient elution. The total run time and the elution time of dacomitinib were 3.0 min and 1.07 min, respectively. Positive-ion electrospray ionization (ESI) and multiple reaction monitoring (MRM) on a triple quadrupole tandem mass spectrometer were used for detection at the transitions of m/z 470.1 → 124.1 for dacomitinib and m/z 441.2 → 84.3 for ibrutinib (IS), respectively. In the range of 1-150 ng/mL, the calibration curve of dacomitinib was linear with a lower limit of quantitation (LLOQ) of 1 ng/mL. Mean recovery of dacomitinib in plasma was in the range of 76.9-84.1%. The inter- and intra-day precision (RSD) was in the scope of 1.7-8.7% and the accuracy (RE) ranged from -6.1 to 8.5%. Stability studies under different conditions were indicated to be stable. A pharmacokinetic study after oral administration of 40 mg/kg dacomitinib in rats illustrated the applicability of the new presented determination of dacomitinib.

Effects of secondary EGFR mutations on resistance against upfront osimertinib in cells with EGFR-activating mutations in vitro

OBJECTIVES

Non-small cell lung cancers (NSCLCs) that harbor activating mutations for epidermal growth factor receptor (EGFR) show remarkable initial response to EGFR-tyrosine kinase inhibitors (TKIs), but inevitably acquire resistance, half of which are due to a T790 M secondary mutation when first-generation (1 G) or 2 G EGFR-TKIs are used. Osimertinib, a 3 G EGFR-TKI, is a standard of care in this situation, but eventually also evokes resistance, reportedly due to some tertiary EGFR mutations. However, the FLAURA trial showed the superiority of osimertinib over 1 G EGFR-TKIs in treatment-naïve patients, thus providing an option of first-line osimertinib treatment. Resistance in this setting is also inevitable, but its mechanism is unclear. We investigated whether resistance mutations that emerged with T790 M were responsible for the osimertinib resistance in the first-line setting; i.e. without T790 M, and if so, what treatment option was available.

MATERIALS AND METHODS

We used literature search to identify EGFR mutations at codons L718, G724, L792, G796, and C797 as mechanisms of osimertinib resistance in the presence of T790 M. These mutations were introduced into Ba/F3 cells in cis with activating EGFR mutations but not with T790 M; inhibitory effects of five EGFR-TKIs were evaluated.

RESULTS

Only C797S conferred significant resistance against osimertinib when exon 19 deletion was the activating mutation. However, co-existence of L858R with C797S, C797 G, L718Q, or L718 V mutations all conferred resistance to osimertinib. Erlotinib showed the greatest activity for C797S-mediated resistance. However, 2 G EGFR-TKIs (afatinib or dacomitinib) were effective for other resistance mutations.

CONCLUSION

After first-line osimertinib failure, 1 G or 2 G EGFR-TKIs are effective, depending on combinations of secondary and activating mutations.

Activity of a novel HER2 inhibitor, poziotinib, for HER2 exon 20 mutations in lung cancer and mechanism of acquired resistance: An in vitro study

OBJECTIVES

Oncogenic HER2 mutations are present in 2-4% of lung adenocarcinomas, but the relevant clinical trials are unsatisfactory. The novel HER2 inhibitor poziotinib was recently developed and clinical trials are ongoing. We compared poziotinib with nine tyrosine kinase inhibitors (TKIs), and derived poziotinib-resistant clones to investigate the resistant mechanism.

MATERIALS AND METHODS

We introduced three common HER2 mutations A775_G776insYVMA (YVMA), G776delinsVC (VC) and P780_Y781insGSP (GSP), which account for 94% of HER2 exon 20 insertions in the literature, into Ba/F3 cells. We then compared the activity of poziotinib with that of nine TKIs (erlotinib, afatinib, dacomitinib, neratinib, osimertinib, AZ5104, pyrotinib, lapatinib, and irbinitinib), determined the 90% inhibitory concentration (IC₉₀) through a growth inhibition assay, and defined a sensitivity index (SI) as IC₉₀ divided by the trough concentration at the recommended dose as a surrogate for drug activity in humans. We also generated resistant clones by exposure to poziotinib in the presence of N-ethyl-N-nitrosourea, and HER2 secondary mutations that might serve as a resistance mechanism were searched.

RESULTS

YVMA showed resistance to all tested drugs except neratinib, poziotinib and pyrotinib. Poziotinib was the only drug with an SI less than 10 for YVMA, the most common HER2 exon 20 insertion. We established 62 poziotinib-resistant clones, and among these, only C805S of HER2, which is homologous to C797S of the EGFR, was identified as a secondary mutation in 19 clones. We also revealed that heat shock protein (HSP) 90 inhibitors show potent anti-growth activity to the C805S secondary mutant clone.

CONCLUSIONS

Poziotinib showed the most potent activity against HER2 exon 20 mutations. We identified the secondary C805S at the covalent binding site of HER2 to poziotinib as a potential mechanism of acquired resistance. HSP90 inhibitors might be a therapeutic strategy for the C805S secondary mutation.