Pilot Study of Dacomitinib for Patients With Metastatic EGFR-Mutant Lung Cancers With Disease Progression After Initial Treatment With Osimertinib

Clinical Efficacy and Safety of First- or Second-Generation EGFR-TKIs after Osimertinib Resistance for EGFR Mutated Lung Cancer: A Prospective Exploratory Study

BACKGROUND

Osimertinib monotherapy is a common treatment for epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC); however, standard treatment strategies for acquired resistance to this drug have not been established. In addition, the clinical significance of first-generation (1G) or second-generation (2G) EGFR-tyrosine kinase inhibitors (TKI) in patients with EGFR-mutant NSCLC and osimertinib resistance has not yet been fully evaluated.

OBJECTIVE

We aimed to conduct a prospective multicenter observational study to evaluate the efficacy and safety of 1G and 2G EGFR-TKIs after the development of osimertinib resistance.

METHODS

Patients with EGFR-mutant NSCLC who received 1G or 2G EGFR-TKIs after developing resistance to osimertinib monotherapy were prospectively assessed at eight institutions in Japan. The primary endpoint was progression-free survival (PFS).

RESULTS

A total of 29 patients with advanced or recurrent EGFR-mutant NSCLC were analyzed. The objective response and disease control rates were 6.9% (2/29) and 58.6% (17/29), respectively. The median PFS was 1.9 months [95% confidence interval (CI): 1.3-5.3]. There was no significant difference in PFS between the 1G and 2G EGFR-TKI groups (3.7 versus 1.5 months, log-rank test p = 0.20). However, patients with normal cytokeratin 19 fragment (CYFRA 21-1) and pro-gastrin-releasing peptide (ProGRP) levels experienced longer PFS than those with elevated CYFRA 21-1 and/or ProGRP (5.5 versus 1.3 months, log-rank test p < 0.001).

CONCLUSION

Administration of 1G or 2G EGFR-TKIs after the development of osimertinib resistance has limited efficacy in patients with EGFR-mutant NSCLC. Moreover, normal CYFRA 21-1 and ProGRP levels could be promising indicators for 1G and 2G EGFR-TKI administration after osimertinib resistance development.

TRIAL REGISTRATION NUMBER

UMIN000044049.

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.

Brief Report: Combination of Osimertinib and Dacomitinib to Mitigate Primary and Acquired Resistance in EGFR-Mutant Lung Adenocarcinomas

PURPOSE

Primary and acquired resistance to osimertinib remain significant challenges for patients with EGFR-mutant lung cancers. Acquired EGFR alterations such as EGFR T790M or C797S mediate resistance to EGFR tyrosine kinase inhibitors (TKI) and combination therapy with dual EGFR TKIs may prevent or reverse on-target resistance.

PATIENTS AND METHODS

We conducted two prospective, phase I/II trials assessing combination osimertinib and dacomitinib to address on-target resistance in the primary and acquired resistance settings. In the initial therapy study, patients received dacomitinib and osimertinib in combination as initial therapy. In the acquired resistance trial, dacomitinib with or without osimertinib was administered to patients with EGFR-mutant lung cancers with disease progression on osimertinib alone and evidence of an acquired EGFR second-site mutation.

RESULTS

Cutaneous toxicities occurred in 93% (any grade) of patients and diarrhea in 72% (any grade) with the combination. As initial therapy, the overall response to the combination was 73% [95% confidence interval (CI), 50%-88%]. No acquired secondary alterations in EGFR were observed in any patients at progression. In the acquired resistance setting, the overall response was 14% (95% CI, 1%-58%).

CONCLUSIONS

We observed no acquired secondary EGFR alterations with dual inhibition of EGFR as up-front treatment, but this regimen was associated with greater toxicity. The combination was not effective in reversing acquired resistance after development of a second-site acquired EGFR alteration. Our study highlights the need to develop better strategies to address on-target resistance in patients with EGFR-mutant lung cancers.

PROTAC therapy as a new targeted therapy for lung cancer

Despite recent advances in molecular therapeutics, lung cancer is still a leading cause of cancer deaths. Currently, limited targeted therapy options and acquired drug resistance present significant barriers in the treatment of patients with lung cancer. New strategies in drug development, including those that take advantage of the intracellular ubiquitin-proteasome system to induce targeted protein degradation, have the potential to advance the field of personalized medicine for patients with lung cancer. Specifically, small molecule proteolysis targeting chimeras (PROTACs), consisting of two ligands connected by a linker that bind to a target protein and an E3 ubiquitin ligase, have been developed against many cancer targets, providing promising opportunities for advanced lung cancer. In this review, we focus on the rationale for PROTAC therapy as a new targeted therapy and the current status of PROTAC development in lung cancer.

Treatment Strategies for Non-Small Cell Lung Cancer with Common EGFR Mutations: A Review of the History of EGFR TKIs Approval and Emerging Data

The development of targeted therapies over the past two decades has led to a dramatic change in the management of EGFR-mutant non-small cell lung cancer (NSCLC). While there are currently five approved EGFR tyrosine kinase inhibitors (TKIs) for treating EGFR-mutant NSCLC in the first-line setting, therapy selection after progression on EGFR TKIs remains complex. Multiple groups are investigating novel therapies and drug combinations to determine the optimal therapy and treatment sequence for these patients. In this review, we summarize the landmark trials and history of the approval of EGFR TKIs, their efficacy and tolerability, and the role of these therapies in patients with central nervous system metastasis. We also briefly discuss the mechanisms of resistance to EGFR TKIs, ongoing attempts to overcome resistance and improve outcomes, and finalize by offering treatment sequencing recommendations.

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.

Resistance mechanisms to osimertinib and emerging therapeutic strategies in nonsmall cell lung cancer

PURPOSE OF REVIEW

This review aims to introduce the resistance mechanisms to osimertinib, discuss the therapeutic strategies, and make clinical updates in overcoming resistance to osimertinib.

RECENT FINDINGS

Osimertinib has shown favorable efficacy on second-line and first-line treatments in EGFR-mutant advanced nonsmall cell lung cancer (NSCLC). However, the presence of primary and acquired resistance to osimertinib restricts its clinical benefits. The primary resistance mainly consists of BIM deletion polymorphism and EGFR exon 20 insertions. Meanwhile, the heterogeneous mechanisms of acquired resistance include EGFR-dependent (on-target) and EGFR-independent (off-target) mechanisms. EGFR C797S mutation, MET amplification, HER2 amplification, and small cell lung cancer transformation were identified as frequent resistance mechanisms. Recently, more novel mechanisms, including rare EGFR point mutations and oncogenic fusions, were reported. With the results of completed and on-going clinical trials, the emerging therapeutic strategies of postosimertinib progression are summarized.

SUMMARY

The resistance mechanisms to osimertinib are heterogeneous and gradually perfected. The combination of osimertinib with bypass targeted therapy and other therapeutic approaches emerge as promising strategies.

Afatinib After Progression on Osimertinib in EGFR-Mutated Non-Small Cell Lung Cancer

INTRODUCTION

After the development of acquired resistance to osimertinib, the standard-of-care treatment for advanced EGFR-mutated NSCLC is chemotherapy. Whether afatinib, a pan-ErbB family tyrosine kinase inhibitor, is active after progression on osimertinib is unknown.

METHODS

We conducted a single-institution retrospective analysis of patients with advanced EGFR-mutated NSCLC who received afatinib-containing therapy after progression on osimertinib. Kaplan-Meier analyses evaluated progression-free survival (PFS) and overall survival (OS) from initiation of afatinib.

RESULTS

After progression on first (N=3) or second-line plus (N=12) osimertinib, 15 patients received afatinib monotherapy (N=3), afatinib and cetuximab (N=10), or afatinib and bevacizumab (N=2). The objective response rate was 6.7% and disease control rate was 53.3%. Median PFS was 2.5 months and median OS was 7.7 months. Median PFS of ≥ 6 months versus < 6 months on osimertinib was associated with a significantly greater median PFS on afatinib (4.0 versus 1.4 months; P=0.003), although there was no significant difference in median OS (9.3 versus 6.6 months; P=0.123). Best response of stable disease/partial response versus progressive disease on osimertinib was associated with a significantly greater median PFS on afatinib (3.4 versus 1.6 months; P=0.036) and a significantly greater median OS (8.7 versus 4.6 months; P=0.017).

CONCLUSION

Afatinib-containing therapy had limited activity in patients with EGFR-mutated NSCLC after progression on osimertinib in this cohort of mostly second-line plus osimertinib. Response and longer PFS to prior osimertinib may be predictive of response to afatinib. Strategies based on osimertinib resistance mechanisms may further define the role of subsequent afatinib.

An open-label expanded access program of afatinib in EGFR tyrosine kinase inhibitor-naïve patients with locally advanced or metastatic non-small cell lung cancer harboring EGFR mutations

BACKGROUND

Afatinib is approved globally for EGFR-TKI treatment-naïve patients with EGFR mutation-positive non-small cell lung cancer (NSCLC). In this Korean expanded access program, we evaluated its 'real-world' safety and efficacy.

METHODS

EGFR-TKI treatment-naïve patients with EGFR mutation-positive NSCLC received afatinib 40 mg/day until disease progression or other withdrawal criteria. Dose reductions were permitted for adverse events (AEs). The primary endpoint was the number of patients with AEs (CTCAE version 3.0). Other endpoints included progression-free survival (PFS), overall response rate (ORR), duration of response (DOR), and changes in investigator-assessed cancer-related symptoms.

RESULTS

Eighty-eight patients received afatinib, including 27 (31%) with brain metastases and 16 (18%) with uncommon EGFR mutations. Median PFS was 17.0 months (95% confidence interval [CI] 12.9-23.3 months). Grade 3 treatment-related AEs (TRAEs) were reported in 51 (58%) patients; the most common were diarrhea (22%) and rash/acne (20%). No grade > 3 TRAEs were reported. AEs leading to dose reduction occurred in 49 (56%) patients. Treatment discontinuation due to TRAEs occurred in 4 (5%) patients. ORR was 81% overall, 89% in patients with brain metastases, and 55% in patients with uncommon mutations (excluding T790M/exon 20 insertions). Median DOR was 15.1 months (95% CI 12.4-21.4 months). Cancer-related symptoms were improved/unchanged/worsened in 34-66%/36-66%/0-3% of patients over the first year.

CONCLUSIONS

No unexpected safety signals for afatinib were observed. AEs were manageable; the treatment discontinuation rate was low. Afatinib showed encouraging efficacy in a broad patient population including those with brain metastases or tumors harboring uncommon EGFR mutations.

TRIALS REGISTRATION

ClinicalTrials.gov NCT01931306 ; 29/08/2013.