Targeting EGFR Exon 20 Insertion Mutation in Non-small cell Lung Cancer: Amivantamab and Mobocertinib

Better safe than sorry: dual targeting antibodies for cancer immunotherapy

Antibody-based therapies are revolutionizing cancer treatment and experience a steady increase from preclinical and clinical pipelines to market share. While the clinical success of monoclonal antibodies is frequently limited by low response rates, treatment resistance and various other factors, multispecific antibodies open up new prospects by addressing tumor complexity as well as immune response actuation potently improving safety and efficacy. Novel antibody approaches involve simultaneous binding of two antigens on one cell implying increased specificity and reduced tumor escape for dual tumor-associated antigen targeting and enhanced and durable cytotoxic effects for dual immune cell-related antigen targeting. This article reviews antibody and cell-based therapeutics for oncology with intrinsic dual targeting of either tumor cells or immune cells. As revealed in various preclinical studies and clinical trials, dual targeting molecules are promising candidates constituting the next generation of antibody drugs for fighting cancer.

Current status and breakthroughs in treating advanced non-small cell lung cancer with EGFR exon 20 insertion mutations

Recently, targeted therapy and immunotherapy have emerged as effective treatment options for non-small cell lung cancer (NSCLC). This progress has been facilitated by the rapid development of diagnostic and therapeutic technologies and the continuous research and development of new drugs, leading to a new era in precision medicine for NSCLC. This is a breakthrough for patients with common mutations in the human epidermal growth factor receptor (EGFR) gene in NSCLC. Consequently, the use of targeted drugs has significantly improved survival. Nevertheless, certain rare genetic mutations are referred to as EGFR exon 20 insertion (ex20ins) mutations, which differ in structure from conventional EGFR gene mutations, namely, exon 19 deletion mutations (19-Del) and exon 21 point mutations. Owing to their distinct structural characteristics, patients harboring these EGFR ex20ins mutations are unresponsive to traditional tyrosine kinase inhibitor (TKI) therapy. This particular group of patients did not fall within the scope of their applicability. However, the activating A763_Y764insFQEA mutation elicits a more pronounced response than mutations in the near and far regions of the C-helix immediately following it and should, therefore, be treated differently. Currently, there is a lack of effective treatments for EGFR ex20ins mutations NSCLC. The efficacy of chemotherapy has been relatively favorable, whereas the effectiveness of immunotherapy remains ambiguous owing to inadequate clinical data. In addition, the efficacy of the first- and second-generation targeted drugs remains limited. However, third-generation and novel targeted drugs have proven to be effective. Although novel EGFR-TKIs are expected to treat EGFR ex20ins mutations in patients with NSCLC, they face many challenges. The main focus of this review is on emerging therapies that target NSCLC with EGFR ex20ins and highlight major ongoing clinical trials while also providing an overview of the associated challenges and research advancements in this area.

Matching-adjusted indirect comparison of amivantamab vs mobocertinib in platinum-pretreated EGFR Exon 20 insertion-mutated non-small-cell lung cancer

Aim: We assessed relative efficacy and safety of amivantamab versus mobocertinib in patients with non-small-cell lung cancer with EGFR exon 20 insertion (exon20ins) mutations who progressed on prior platinum-based chemotherapy. Materials & methods: This matching-adjusted indirect comparison used patient-level data from CHRYSALIS (NCT02609776) and aggregate data from a mobocertinib trial (NCT02716116) to match populations on all clinically relevant confounders. Results: While both agents had similar efficacy for time-to-event outcomes, objective response rate was significantly higher for amivantamab. 15 of 23 any-grade treatment-related adverse events reported for mobocertinib were significantly less common for amivantamab versus only two for mobocertinib. Conclusion: Results suggest that amivantamab has an improved response rate with similar survival and a more favorable safety profile versus mobocertinib in EGFR exon20ins non-small-cell lung cancer.

Real-World Response and Outcomes in Patients With NSCLC With EGFR Exon 20 Insertion Mutations

Introduction

This study describes treatment patterns and outcomes in patients with NSCLC with EGFR exon 20 insertions (EGFRex20ins) in the United States.

Methods

The Flatiron Health electronic health record database was used to select three cohorts among patients diagnosed with NSCLC with EGFRex20ins (January 1, 2011-February 29, 2020): (1) first-line (1L) or patients receiving 1L therapy after documented EGFRex20ins; (2) second or later-line (≥2L) or patients receiving ≥2L therapy after documented EGFRex20ins; and (3) ≥2L postplatinum trial-aligned, or ≥2L patients previously treated with platinum chemotherapy whose baseline characteristics aligned with key eligibility criteria (initiating new treatment after documented EGFRex20ins and ≥1 previous treatment excluding mobocertinib or amivantamab) of the mobocertinib trial NCT02716116. Real-world end points were confirmed overall response rate, overall survival, and progression-free survival.

Results

Of 237 patients with EGFRex20ins-mutated NSCLC, 129 and 114 patients were included in the 1L and ≥2L cohorts, respectively. In 1L patients, platinum chemotherapy plus nonplatinum chemotherapy (31.0%) and EGFR tyrosine kinase inhibitors (28.7%) were the most common regimens. In ≥2L patients, immuno-oncology monotherapy (28.1%) and EGFR tyrosine kinase inhibitors (17.5%) were the most common index treatments. For any 1L, ≥2L, and ≥2L postplatinum trial-aligned patients, the confirmed overall response rate was 18.6%, 9.6%, and 14.0%, respectively; the median overall survival was 17.0, 13.6, and 11.5 months; the median progression-free survival was 5.2, 3.7, and 3.3 months, respectively.

Conclusions

The outcomes for patients with NSCLC with EGFRex20ins were poor. This real-world study provides a benchmark on treatment outcomes in this patient population and highlights the unmet need for improved therapeutic options.

Clinical Utility of Mobocertinib in the Treatment of NSCLC - Patient Selection and Reported Outcomes

Mobocertinib is an oral tyrosine kinase inhibitor (TKI) that selectively targets epidermal growth factor receptor exon 20 insertion (EGFRex20ins) mutations. It is a structural analog of the third-generation TKI osimertinib, which targets EGFR T790M mutant non-small cell lung cancer (NSCLC); however, mobocertinib gains selectivity for EGFRex20ins mutants over wild type (WT) by interacting with the C790 gatekeeper residue of EGFR. This is accomplished via a carboxylated isopropyl ester moiety at the C5-position of mobocertinib's central pyrimidine core. In Phase 1/2 dose-escalation and dose-expansion studies, mobocertinib was found to have an investigator-confirmed overall response rate (ORR) of 56% (9/16; 95% CI: 30-80%) and 25% (3/12; 95% CI: 5-57%) in patients without and with baseline brain metastasis, respectively. Median investigator-assessed progression-free survival (mPFS) was 10.2 months (95% CI: 5.6 - not reached) and 3.7 months (95% CI: 1.8-15.9) in patients without and with baseline brain metastasis, respectively. A third phase evaluated patients who had received pre-treatment with platinum-based chemotherapy (PPP) and included an extension cohort (EXCLAIM cohort) which evaluated patients treated previously with 1 or 2 lines of therapy. An Independent Review Committee (IRC) found both cohorts to have similar outcomes in terms of ORR, median time to response, mPFS, and disease progression or death. The treatment-emergent adverse events (TEAE) related to mobocertinib are similar to other EGFR inhibitors and are predominately gastrointestinal (eg diarrhea, nausea, vomiting) and cutaneous (eg rash). In September 2021, the FDA granted accelerated approval for mobocertinib in the treatment of patients with locally advanced or metastatic NSCLC with EGFRex20ins mutation whose disease progressed while on platinum-based chemotherapy. The present review describes data that led to the approval of mobocertinib.

Discovery of mobocertinib, a new irreversible tyrosine kinase inhibitor indicated for the treatment of non-small-cell lung cancer harboring EGFR exon 20 insertion mutations

Epidermal growth factor receptor (EGFR) is essential for normal cellular functions. Mutations of EGFR's kinase domain can cause dysregulation leading to non-small cell lung cancer (NSCLC). Exon 20 insertion (ex20ins) mutations in EGFR are one of the leading contributors to oncogenesis and confer insensitivity to most available therapeutics. Mobocertinib is a novel tyrosine kinase inhibitor (TKI) recently approved by the US FDA as a first-in-class small molecule therapeutic for EGFR ex20ins-positive NSCLC. When compared to osimertinib, a TKI indicated for the treatment of EGFR T790M-positive NSCLC, mobocertinib differs only by the presence of an additional C5-carboxylate isopropyl ester group on the middle pyrimidine core. Together with the acrylamide side chain that is responsible for irreversible inhibition, this additional C5-substituent affords mobocertinib high anticancer potency and specificity to EGFR ex20ins-positive lung cancer that is resistant to other EGFR TKIs. This review article provides an overview of the discovery of mobocertinib from osimertinib including their structure-activity relationships, mechanisms of action, preclinical pharmacology, pharmacokinetics, and clinical applications. The discovery and use of mobocertinib and other EGFR TKIs demonstrate the power of structure-based drug design and promising therapeutic outcomes of using precision medicine approaches in the management of molecularly defined tumors. Graphical abstract.