How Amivantamab Works — and Why the Dual EGFR/MET Design Matters
Amivantamab is a full-length bispecific antibody that simultaneously binds both EGFR and MET (c-Met/HGFR), derived from anti-EGFR antibody 12H2 and anti-MET antibody 13C6. By engaging both receptors at once, it executes three distinct anti-tumour mechanisms: blocking ligand binding to EGFR and MET, promoting receptor degradation, and arming Fc-gamma-receptor-expressing immune effector cells for antibody-dependent cellular cytotoxicity (ADCC) and trogocytosis — a physical stripping of receptor from the tumour cell surface.
The decision to include a MET arm was not arbitrary. MET amplification is a well-characterised escape route for tumours under EGFR-targeted pressure, and the bispecific format means a single molecule can simultaneously suppress both the primary driver and its most common bypass mechanism. This mechanistic logic — co-targeting the driver and its dominant resistance pathway from the outset — is the design principle that distinguishes amivantamab from earlier single-agent EGFR antibodies and small molecule inhibitors.
EGFR exon 20 insertion mutations are in-frame insertions in the exon 20 region of the EGFR kinase domain, clustered near residues 767–774. They cause conformational changes in the kinase domain that confer resistance to first- and second-generation EGFR tyrosine kinase inhibitors (TKIs), creating a distinct patient population with historically limited treatment options. Over 100 distinct insertion subtypes have been identified, according to research published in peer-reviewed oncology literature.
The antibody’s binding profile is deliberately broad: it targets both wild-type EGFR and mutant EGFR including exon 20 insertion variants. This distinguishes it from small molecule approaches that aim for mutant-selective inhibition. The trade-off — greater on-target coverage at the cost of some wild-type EGFR engagement — is a deliberate strategic choice, and the clinical data from the PAPILLON trial vindicated it.
Amivantamab is a bispecific antibody derived from anti-EGFR antibody 12H2 and anti-MET antibody 13C6. It simultaneously blocks ligand binding to both EGFR and MET, promotes receptor degradation, and arms immune effector cells for ADCC and trogocytosis in NSCLC with EGFR exon 20 insertion mutations.
PAPILLON and the EGFR Exon 20 Insertion Landscape: From Unmet Need to Standard of Care
The PAPILLON Phase 3 clinical trial established amivantamab combined with carboplatin-pemetrexed chemotherapy as a new standard-of-care option for first-line EGFR exon 20 insertion NSCLC, demonstrating significantly improved progression-free survival compared to chemotherapy alone. This was a pivotal result for a patient population that had, until recently, been largely excluded from the precision oncology advances benefiting patients with classical EGFR mutations such as exon 19 deletions and L858R substitutions.
The significance of PAPILLON extends beyond the headline efficacy data. The trial validated the combination of a bispecific antibody with platinum-based chemotherapy as a viable first-line strategy for a mutation-defined patient subgroup — a design template now being applied across the broader NSCLC mutation landscape. According to research published in peer-reviewed oncology literature, EGFR exon 20 insertion mutations comprise approximately 4–10% of EGFR-mutant NSCLC, with over 100 distinct insertion subtypes identified and hotspot insertions clustered near residues 767–774 of the EGFR kinase domain.
“Over 100 distinct EGFR exon 20 insertion subtypes have been identified — the molecular heterogeneity of this patient population is one reason earlier broad-spectrum EGFR TKIs consistently failed to deliver.”
That heterogeneity is clinically significant. The conformational changes caused by exon 20 insertions in the kinase domain confer resistance to first- and second-generation EGFR TKIs, which were designed for the classical activating mutations. Wild-type-sparing approaches — whether small molecule or antibody-based — are needed to reduce the on-target toxicity that arises from inhibiting normal EGFR in skin, gut, and other tissues. Janssen’s additional patent filing for a subcutaneous formulation of amivantamab (US20230357413A1) signals a commercial strategy to address the administration burden of intravenous therapy and improve patient adherence over the treatment course.
The PAPILLON Phase 3 clinical trial demonstrated that amivantamab combined with carboplatin-pemetrexed chemotherapy significantly improved progression-free survival versus chemotherapy alone as first-line treatment for NSCLC with EGFR exon 20 insertion mutations, establishing this combination as a new standard-of-care option.
Track amivantamab patent filings, PAPILLON trial data, and competing EGFR exon 20 programmes in real time.
Explore EGFR Exon 20 Patent Landscape in PatSnap Eureka →Resistance Mechanisms Shaping the Next Wave of Combinations
MET amplification is the primary resistance mechanism to EGFR exon 20 insertion-targeted therapy — and this single biological fact explains the entire strategic architecture of amivantamab. Acquired resistance to EGFR-targeted agents also includes on-target EGFR secondary mutations such as C797S, and activation of bypass signalling pathways involving HER2, HER3, and MET. Each of these pathways represents both a clinical challenge and an IP opportunity, and the patent landscape reflects this clearly.
Janssen has filed multiple combination therapy patents addressing the post-progression setting. US20230248838A1 covers the combination of amivantamab with lazertinib (a third-generation EGFR TKI) for patients who have failed prior EGFR-targeted therapy, with the MET arm of amivantamab specifically designed to counter MET amplification-driven escape. The MARIPOSA clinical trial, referenced in patent filings, demonstrated superior progression-free survival for the amivantamab plus lazertinib combination compared to osimertinib alone in EGFR-mutant NSCLC. A further patent (US20220204604A1) covers the amivantamab plus osimertinib combination, with the MARIPOSA-2 trial evaluating a three-drug regimen of amivantamab, osimertinib, and lazertinib for platinum-pretreated EGFR-mutant NSCLC.
Acquired resistance to EGFR exon 20 insertion-targeted therapy includes on-target EGFR secondary mutations (notably C797S) and MET amplification as a bypass mechanism. HER2, HER3, and MET bypass signalling activation are also documented resistance pathways. This mechanistic landscape is driving combination therapy patent filings that pair amivantamab with third-generation EGFR TKIs, and informing the design of next-generation bispecific approaches targeting EGFR alongside HER3 (e.g., MCLA-128 from Merus NV).
The emergence of HER3 as a bypass resistance mechanism is particularly notable. Patent US20240092905A1, filed by Merus NV, covers a bispecific anti-EGFR/HER3 antibody (MCLA-128) that simultaneously targets EGFR and HER3 — directly addressing the HER3-mediated bypass that can develop under EGFR-targeted therapy. According to research published by organisations including Nature, HER3 is a key bypass resistance mechanism for EGFR-targeted therapies, and its targeting represents the next frontier in combination strategy design. The NIH‘s National Cancer Institute has similarly highlighted bypass signalling as a central challenge in durable EGFR inhibition.
MET amplification is the primary resistance mechanism to EGFR exon 20 insertion-targeted therapy in NSCLC. Acquired resistance also includes on-target EGFR secondary mutations such as C797S and activation of bypass signalling pathways involving HER2, HER3, and MET — each of which is now a target for next-generation combination therapy patent filings.
The HER2 Exon 20 Insertion Race: A Parallel Playbook Unfolding in Real Time
HER2 exon 20 insertions are found in approximately 2–4% of NSCLC — a frequency comparable to, though somewhat lower than, EGFR exon 20 insertions. The YVMA insertion is the most common HER2 mutation subtype. Both mutations share parallel biology as distinct oncogenic drivers, and both have historically lacked approved targeted therapies. The success of amivantamab in EGFR exon 20 insertion NSCLC has accelerated investment in the HER2 exon 20 insertion space, with multiple modalities now in active development.
The leading clinical asset in the HER2 exon 20 insertion space is trastuzumab deruxtecan (T-DXd), a HER2-targeting antibody-drug conjugate (ADC) developed by Daiichi Sankyo and AstraZeneca. In the DESTINY-Lung02 Phase 2 trial, T-DXd achieved an overall response rate of 49.0% in HER2-mutant NSCLC, with a median progression-free survival of 9.9 months. The majority of HER2 mutations in the trial were exon 20 insertions, establishing T-DXd as the reference treatment for HER2-mutant NSCLC — a position directly analogous to amivantamab’s role in EGFR exon 20 insertion disease. According to data reported to ASCO, these results represent a step-change in outcomes for a population previously limited to chemotherapy.
The ADC mechanism differs fundamentally from amivantamab’s bispecific approach. T-DXd delivers a topoisomerase I inhibitor payload selectively to HER2-expressing tumour cells, with a bystander killing effect that can affect adjacent HER2-negative cells. Janssen, meanwhile, has filed a separate patent (US20220411505A1) for a HER2/MET bispecific antibody — derived from anti-HER2 antibody 1C6 and anti-MET antibody 13C6 — that mirrors the EGFR/MET architecture of amivantamab but targets HER2. Zymeworks has filed a bispecific EGFR/HER2 antibody patent (US20230203181A1) for simultaneous blocking of both receptor tyrosine kinases. Boehringer Ingelheim has filed for selective HER2 kinase inhibitors (US20230406899A1) targeting HER2 over EGFR, distinguishing them from pan-HER inhibitors.
Trastuzumab deruxtecan (T-DXd) achieved an overall response rate of 49.0% and a median progression-free survival of 9.9 months in HER2-mutant NSCLC in the DESTINY-Lung02 Phase 2 trial, where the majority of HER2 mutations were exon 20 insertions. HER2 exon 20 insertions are found in approximately 2–4% of NSCLC patients.
Patent Signals: What the Filing Landscape Tells Drug Discovery Teams Right Now
Patent activity in EGFR exon 20 insertion NSCLC and HER2 exon 20 insertion NSCLC reveals a field in rapid competitive transition. Janssen Biotech’s filing portfolio spans the full amivantamab lifecycle: the original EGFR/MET bispecific mechanism (US20220411515A1), combination with lazertinib (US20230340142A1), combination with osimertinib (US20220204604A1), subcutaneous formulation (US20230357413A1), and a digital health biomarker monitoring system (US20230149539A1). This breadth signals a deliberate lifecycle management strategy — protecting not just the molecule but the combination regimens, delivery formats, and monitoring infrastructure that maximise commercial durability.
In the small molecule space, Blueprint Medicines (US20230174638A1) and Shanghai Allist Pharmaceuticals (US20230312741A1) have filed for mutant-selective EGFR exon 20 inhibitors that spare wild-type EGFR — addressing the dose-limiting GI toxicity that constrained mobocertinib, which achieved a 28% overall response rate in previously treated EGFR exon 20 insertion NSCLC patients but was limited by wild-type EGFR inhibition. Mobocertinib targets the P-loop and αC-helix of the EGFR kinase domain, which is structurally altered by exon 20 insertions. The next generation of small molecules aims to improve on this selectivity profile.
Pfizer’s PCT filing (WO2022213016A2) for combination therapies using anti-EGFR and anti-MET antibodies — including carboplatin and pemetrexed combinations — indicates that the amivantamab combination regimen template is being studied by competitors. The convergence of multiple large pharmaceutical companies around the same mechanism and combination backbone is a reliable indicator of a market that has reached clinical validation and is now entering the competitive differentiation phase, as documented in WIPO‘s global patent trend analyses for oncology biologics.
Map the full competitive patent landscape for EGFR and HER2 exon 20 insertion NSCLC — including assignee clustering, filing velocity, and white-space opportunities.
Analyse the Pipeline in PatSnap Eureka →The cross-pathway combination filing by AstraZeneca (US20240101683A1) — pairing anti-HER2 ADC with an EGFR inhibitor — reflects the recognition that EGFR and HER2 signalling are interrelated in a subset of NSCLC tumours, particularly where HER2 amplification emerges as a resistance mechanism to EGFR inhibition. This mirrors the logic of amivantamab’s dual EGFR/MET targeting, but applied at the combination therapy level rather than within a single molecule. The EPO‘s examination of these cross-pathway combination patents will be a key indicator of how broadly the IP protection for these strategies can be drawn.
For drug discovery and competitive intelligence teams, the key signals from this patent landscape are: first, that the bispecific antibody format has achieved proof of concept in EGFR-driven NSCLC and is now being applied to HER2-driven disease; second, that the combination-with-chemotherapy backbone pioneered by PAPILLON is being replicated across both the EGFR and HER2 exon 20 insertion settings; and third, that formulation innovation — particularly subcutaneous delivery — is becoming a competitive differentiator as the market matures beyond first-mover efficacy advantages. Teams using PatSnap‘s innovation intelligence platform can monitor all of these filing vectors in real time, tracking assignee clustering and filing velocity to identify white-space opportunities before they become contested territory.
Mobocertinib, a small molecule EGFR exon 20 insertion-selective TKI, achieved a 28% overall response rate in EGFR exon 20 insertion NSCLC patients who progressed on prior platinum-based therapy in a Phase 1/2 trial. Dose-limiting GI toxicity from wild-type EGFR inhibition was the primary challenge, driving next-generation mutant-selective inhibitor development by Blueprint Medicines and Shanghai Allist Pharmaceuticals.