Biomarker Consortium

GI Cancer

Gastric Cancer

V-RAF murine sarcoma viral oncogene homolog B1 (BRAF)

The v-Raf murine sarcoma viral oncogene homolog B1 (

) gene was discovered in 1988, and it encodes a kinase protein in the RAS-RAF-MEK-ERK signal transduction pathway.

BRAF is located on chromosome 7 and belongs to the RAF family of serine/threonine-specific protein kinases but is the only one known to be a proto-oncogene in humans.

Under normal circumstances, RAF proteins participate in the RAS-RAF-MEK-ERK pathway, which is involved in cell proliferation and differentiation.

Activated BRAF phosphorylates MEK proteins, which subsequently activate ERK proteins, which activate cellular transcription factors.

BRAF contains 3 conserved regions: CR1, CR2, and CR3. CR1 and CR3 produce autoinhibitory interaction for BRAF, with CR2 functioning as a hinge of the other conserved regions.

 mutation is V600E, resulting in constitutively activated BRAF kinases that stimulate tumor growth.

 mutations occur within 2 different protein locations, exons 11 and 15, resulting in the loss of the autoinhibitory region combined with targeting BRAF to the plasma membrane.

The prevalence of BRAF V600E mutations in gastric cancer is relatively low, ranging from

 mutations in gastric cancer, the role of mutation status and clinicopathological variables is unclear.

BRAF is a known predictor of poor prognosis in colorectal cancer (CRC) to EGFR-targeted agents, but the predictive value in gastric cancer is unknown.

Gastric cancer is characterized by high tumor heterogeneity, so biomarker testing has a high impact on appropriate treatment selection.

Patients with gastric cancer should undergo testing for BRAF mutations and other relevant biomarkers at the time of diagnosis using next-generation sequencing (NGS) at the discretion of the physician.

BRAF testing can be performed using immunohistochemistry (IHC) or, preferably, next-generation sequencing (NGS).

Biomarker testing for gastric cancer should start with IHC and targeted PCR, followed by NGS testing. If tissue is limited or a biopsy isn't feasible, sequential single biomarker testing may deplete the sample.

In these cases, comprehensive genomic profiling via a validated NGS assay is advised. Key biomarkers for interrogation include 

 overexpression, PD-L1 expression, microsatellite instability, tumor mutational burden, 

Gastric cancer accounts for only about 1.5% of new cancer cases in the United States each year.

The relative rarity means that targeted treatments are limited, and most treatments include traditional chemotherapy.

Currently, the only FDA-approved treatment for gastric cancer with a BRAF V600E mutation is dabrafenib plus trametinib.

The treatment of adult and pediatric patients ≥ 1 year who have unresectable or metastatic solid tumors that harbor a 

V600E mutation, whose disease has progressed following prior treatment, and who have no satisfactory alternative treatment options. This indication is approved under accelerated approval based on overall response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

Dabrafenib is an inhibitor of mutated BRAF proteins, which are constitutively active; they stimulate tumor cell proliferation via the MAPK pathway.

Trametinib is a reversible inhibitor of mitogen-activated protein kinase kinase 1 (MEK1) and MEK2.

MEK proteins are upstream regulators of the MAPK pathway.

Tumor cells that initially respond to dabrafenib can develop resistance via the MEK protein, providing the rationale for combination therapy.

Learn more about Dabrafenib and Trametinib >

https://us.tafinlarmekinist.com/metastatic-nsclc/patient-support/patient-resources

Wan PTC, Garnett MJ, Roe SM, et al. Mechanism of activation of the RAF-ERK signaling pathway by oncogenic mutations of B-RAF. 

. 2004;116(6):855-867. doi:10.1016/s0092-8674(04)00215-6

TAFINLAR (dabrafenib). Prescribing information. GSK; 2024. Accessed May 5, 2024. 

https://www.novartis.com/us-en/sites/novartis_us/files/tafinlar.pdf

MEKINIST (trametinib). Prescribing information. Novartis; 2024. Accessed May 5, 2024. 

https://www.novartis.com/us-en/sites/novartis_us/files/mekinist.pdf

Hewitt LC, Hutchins GG, Melotte V, Saito Y, Grabsch HI. KRAS, BRAF and gastric cancer. 

. 2015;4(6). doi:10.3978/j.issn.2224-4778.2015.09.08

Zaman A, Wu W, Bivona TG. Targeting oncogenic BRAF: past, present, and future. 

. 2019;11(8):1197. doi:10.3390/cancers11081197

Choi YY, Noh SH, Cheong JH. Molecular dimensions of gastric cancer: translational and clinical perspectives. 

. 2016;50(1):1-9. doi:10.4132/jptm.2015.09.10

Van Grieken NCT, Aoyma T, Chambers PA, et al. KRAS and BRAF mutations are rare and related to DNA mismatch repair deficiency in gastric cancer from the East and the West: results from a large international multicentre study. 

. 2013;108(7):1495-1501. doi:10.1038/bjc.2013.109

NCCN guidelines version 1.2024: gastric cancer

https://www.nccn.org/professionals/physician_gls/pdf/gastric.pdf

Zhu X, Pigazzi A, Zell J, Lu Y. Changing disparity of gastric cancer incidence by histological types in US race-specific populations. 

 2020;27(1):1073274820977152. doi:10.1177/1073274820977152

National Comprehensive Cancer Network. NCCN guidelines version 1.2024: pancreatic adenocarcinoma. 2024. Accessed May 5, 2024. 

https://www.nccn.org/professionals/physician_gls/pdf/pancreatic.pdf

Salama AKS, Li S, Macrae ER, et al. Dabrafenib and trametinib in patients with tumors with BRAF V600E mutations: results of the NCI-MATCH trial subprotocol H. 

. 2020;38(33):3895-3904. doi:10.1200/JCO.20.00762

Subbiah V, Kreitman RJ, Wainberg ZA, et al. Dabrafenib plus trametinib in BRAFV600E-mutated rare cancers: the phase 2 ROAR trial. 

. 2023;29(5):1103-1112. doi:10.1038/s41591-023-02321-8

BRAF V600E

Neurotrophic tropomyosin kinase receptors (NTRK)

Neurotrophic tropomyosin kinase receptors (NTRK) are transmembrane kinases involved in neural cells’ development, proliferation, and survival.

After localization to cell membranes, the protein family is activated by nerve growth factor (NGF) ligands, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), NT-4, and NT-5.

The TRK family consists of 3 members, including TKRA, TKRB, and TRKC and activation of these proteins leads to downstream activation of the signal pathways RAS-RAF-MEK-ERK, phosphatidylinositol-3 (PI3) kinase, and phospholipase C gamma (PLC-γ).

NTRK genes are proto-oncogenes that activate into oncogenic driver mutations via gene fusions that lead to chimeric TRK proteins.

in solid tumors, but there is a lack of data regarding the prevalence in gastroesophageal cancer.

gene fusions occur through chromosome rearrangements, point mutations, deletions, or gene fusions and cause spontaneous ligand-independent dimerization.

These chimeric proteins have constitutive TRK protein activity or overexpression of the kinase function.

Current research suggests that oncogenic mutations cause a change exclusively in the extracellular domain of chimeric proteins, suggesting a common regulatory domain.

Patients with gastric cancer should undergo testing for 

 gene fusions and other relevant biomarkers at the time of diagnosis using next-generation sequencing (NGS) at the discretion of the physician.

Feasible testing methods include immunohistochemistry (ICH), fluorescence in situ hybridization (FISH), DNA-based next-generation sequencing, and RNA-based NGS.

The ideal approach appears to be RNA-based NGS because of the higher rates of false positives and lack of evidence of functional transcription present in other methods.

Biomarker testing for gastric cancer should start with IHC and targeted PCR, followed by NGS testing.

If tissue is limited or a biopsy isn't feasible, sequential single biomarker testing may deplete the sample. In these cases, comprehensive genomic profiling via a validated NGS assay is advised.

Key biomarkers for interrogation include 

Currently, 2 FDA-approved options exist for treating unresectable or metastatic NTRK gene fusion–positive solid tumors.

Larotrectinib and entrectinib are recommended as second- or subsequent-line treatments in NTRK+ patients. Their favorable safety profile and clinically meaningful response support regular screening for gene fusions.

Approval for larotrectinib was based on the data from 3 trials, LOCO-TRK-14001 (NCT02122913), SCOUT (NCT02637687), and NAVIGATE (NCT02576431).

The overall response rate in 55 patients was 75% (95% CI, 61-85), 71% of responses remained ongoing at 1 year, and 55% remained progression-free at 1 year.

Entrectinib approval was based on data from the trials STARTRK-2 (NCT02568267) and STARTRK-1 (NCT02097810), and ALKA-372-001.

The study population comprised 54 adults with an overall response rate of 57% (95% CI, 43-71), progression-free survival 11.2 months (95% CI, 8.0-14.9), and overall survival 20.9 (95% CI, 14.9-NR).

The FDA has approved entrectinib for the treatment of adult and pediatric patients 12 years of age and older with solid tumors that have a neurotrophic receptor tyrosine kinase (NTRK) gene fusion without a known acquired resistance mutation, are metastatic, or where surgical resection is likely to result in severe morbidity; it is also approved for situations where there are no satisfactory alternative treatments or the patient has progressed following treatment. 

This indication has received accelerated approval based on the overall response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trials.

Entrectinib is an inhibitor of the tropomyosin receptor tyrosine kinases (TRK) TRKA, TRKB, and TRKC (encoded by the neurotrophic tyrosine receptor kinase [NTRK] genes 

 respectively), proto-oncogene tyrosine-protein kinase ROS1 (ROS1), and anaplastic lymphoma kinase (ALK). Entrectinib also inhibits JAK2 and TNK2.

Fusion proteins that include TRK, ROS1, or ALK kinase domains can drive tumorigenic potential through hyperactivation of downstream signaling pathways leading to unconstrained cell proliferation. Entrectinib demonstrated in vitro and in vivo inhibition of cancer cell lines derived from multiple tumor types harboring NTRK, ROS1, and ALK fusion genes.

https://www.gene.com/patients/medicines/rozlytrek

The FDA has approved larotrectinib for the treatment of adult and pediatric patients with solid tumors that have a neurotrophic receptor tyrosine kinase (NTRK) gene fusion without a known acquired resistance mutation, are metastatic, or where surgical resection is likely to result in severe morbidity; it is also approved for situations where there are no satisfactory alternative treatments or the patient has progressed following treatment.

Larotrectinib is an inhibitor of the tropomyosin receptor kinases (TRK), TRKA, TRKB, and TRKC. TRKA, B, and C are encoded by the genes 

Chromosomal rearrangements involving in-frame fusions of these genes with various partners can result in constitutively-activated chimeric TRK fusion proteins that can act as an oncogenic driver, promoting cell proliferation and survival in tumor cell lines. In in vitro and in vivo tumor models, larotrectinib demonstrated anti-tumor activity in cells with constitutive activation of TRK proteins resulting from gene fusions, deletion of a protein regulatory domain, or in cells with TRK protein overexpression.

https://hcp.vitrakvi-us.com/support-and-resources/resources

Manea CA, Badiu DC, Ploscaru IC, et al. A review of NTRK fusions in cancer. 

. 2022;79:103893. doi:10.1016/j.amsu.2022.103893

 fusions: merits and limitations of current diagnostic platforms. 

. 2019;79(13):3163-3168. doi:10.1158/0008-5472.CAN-19-0372

Lange A, Lo HW. Inhibiting TRK proteins in clinical cancer therapy. 

. 2018;10(4):105. doi:10.3390/cancers10040105

Arnold A, Daum S, Von Winterfeld M, et al. Analysis of NTRK expression in gastric and esophageal adenocarcinoma (AGE) with pan-TRK immunohistochemistry. 

. 2019;215(11):152662. doi:10.1016/j.prp.2019.152662

ROZLYTREK (entrectinib). Prescribing information. Genentech; 2019. Accessed May 5, 2024. 

https://www.gene.com/download/pdf/rozlytrek_prescribing.pdf

VITRAKVI (larotrectinib). Prescribing information. Loxo Oncology; 2018. Accessed May 5, 2024. 

https://labeling.bayerhealthcare.com/html/products/pi/vitrakvi_PI.pdf

Drilon A, Laetsch TW, Kummar S, et al. Efficacy of larotrectinib in 

 fusion-positive cancers in adults and children. 

. 2018;378(8):731-739. doi:10.1056/NEJMoa1714448

Demetri GD, Paz-Ares L, Farago AF, et al. Efficacy and safety of entrectinib in patients with NTRK fusion-positive (NTRK-fp) tumors: pooled analysis of STARTRK-2, STARTRK-1 and ALKA-372-001. 

. 2018;29(suppl 8):viii713. doi:10.1093/annonc/mdy424.017

NTRK fusions

) gene is a DNA sequence localized to chromosome 10.

It encodes a glycoprotein membrane receptor with tyrosine kinase activity with 4 cadherin-like domains (CLDs) and a cysteine-rich domain in the extracellular region.

CLDs are involved in calcium-mediated cellular adhesions.

The RET kinase is critical for developing the enteric nervous system during embryogenesis, including thyroid C cells, enteric ganglia, peripheral nervous system (PNS) ganglia, fetal kidney cells, and testes germ cells.

The endogenous ligand for RET protein is glial cell line-derived neurotrophic factor (GDNF), a growth factor-like protein; persephin, neurturin, and artemin.

These ligands do not agonize RET directly but instead attach to a co-receptor GDNF family receptor-α (GDNFα) protein.

After activation, RET homodimerizes, which leads to autophosphorylation of tyrosine residues and activation of multiple signal pathways, including PI3K, MAPK, phospholipase C-γ, JAK-STAT, and PKA.

fusions and rearrangements are present in 0%-2% of solid tumors and are found most commonly in cases of medullary thyroid cancer (>80%) due to their crucial role in the formation of thyroid C cells.

fusions in gastric cancer is even more rare and is 

breakpoints occur in intron 11, followed by introns 10 and 7.

Oncogenesis can occur via several mechanisms, including the alteration of transcriptional control or via fusion partners that dimerize RET proteins independently of endogenous ligands, which leads to constitutive expression.

 mutations and other relevant biomarkers at the time of diagnosis using next-generation sequencing (NGS) at the discretion of the physician.

RET testing can be conducted using immunohistochemistry (IHC) or NGS. However, NGS is the preferred method, as IHC is less reliable for detecting RET alterations due to its low sensitivity and variable specificity.

Biomarker testing for gastric cancer should start with IHC and targeted PCR, followed by NGS testing. If tissue is limited or a biopsy isn't feasible, sequential single biomarker testing may deplete the sample. In these cases, comprehensive genomic profiling via a validated NGS assay is advised. Key biomarkers for interrogation include 

 gene-fusion–positive gastric tumors is selpercatinib, approved in 2022.

Selpercatinib has demonstrated antitumor activity against cells harboring constitutively active RET proteins from gene fusions and mutations.

Selpercatinib is generally well tolerated with a permanent discontinuation rate of 8%.

Adult patients with locally advanced or metastatic solid tumors with a 

 gene fusion that have progressed on or following prior systemic treatment or who have no satisfactory alternative treatment options.

This indication is approved under accelerated approval based on the overall response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trial(s).

Selpercatinib is a kinase inhibitor that inhibits wild-type RET and multiple mutated RET isoforms as well as VEGFR1 and VEGFR3. Selpercatibib also inhibits FGFR 1, 2, and 3 at higher concentrations.

Certain point mutations in RET or chromosomal rearrangements involving in-frame fusions of RET with various partners can result in constitutively activated chimeric RET fusion proteins that can act as oncogenic drivers by promoting cell proliferation of tumor cell lines.

In in vitro and in vivo tumor models, selpercatinib demonstrated anti-tumor activity in cells harboring constitutive activation of RET proteins resulting from gene fusions and mutations, including CCDC6-RET, KIF5B-RET, RET V804M, and RET M918T.

https://retevmo.lilly.com/savings-support

Belli C, Penault-Llorca F, Ladanyi M, et al. ESMO recommendations on the standard methods to detect RET fusions and mutations in daily practice and clinical research. 

. 2021;32(3):337-350. doi:10.1016/j.annonc.2020.11.021

Carlomagno F. Thyroid cancer: role of RET and beyond. 

Drilon A, Hu ZI, Lai GGY, Tan DSW. Targeting RET-driven cancers: lessons from evolving preclinical and clinical landscapes. 

. 2018;15(3):151-167. doi:10.1038/nrclinonc.2017.175

Ibanez CF. Structure and physiology of the RET receptor tyrosine kinase. 

. 2013;5(2):a009134-a009134. doi:10.1101/cshperspect.a009134

Zhao L, Wang N, Zhang D, Jia Y, Kong F. A comprehensive overview of the relationship between RET gene and tumor occurrence. 

. 2023;13:1090757. doi:10.3389/fonc.2023.1090757

Kato S, Subbiah V, Marchlik E, Elkin SK, Carter JL, Kurzrock R. 

 aberrations in diverse cancers: next-generation sequencing of 4,871 patients. 

. 2017;23(8):1988-1997. doi:10.1158/1078-0432.CCR-16-1679

Skórzewska M, Gęca K, Polkowski WP. A clinical viewpoint on the use of targeted therapy in advanced gastric cancer. 

. 2023;15(22):5490. doi:10.3390/cancers15225490

Shi M, Wang W, Zhang J, et al. Identification of RET fusions in a Chinese multicancer retrospective analysis by next-generation sequencing. 

. 2022;113(1):308-318. doi:10.1111/cas.15181

Ferrara R, Auger N, Auclin E, et al. Clinical and translational implications of 

 rearrangements in non-small cell lung cancer. 

Naidoo J, Drilon A. Molecular diagnostic testing in non-small cell lung cancer. 

RETEVMO (selpercatinib). Prescribing information. Eli Lilly and Company; 2022. Accessed May 5, 2024. 

https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/213246s008lbl.pdf

FDA D.I.S.C.O. burst edition: FDA approvals of Retevmo (selpercatinib) for adult patients with locally advanced or metastatic RET fusion-positive solid tumors, and Retevmo (selpercatinib) for adult patients with locally advanced or metastatic RET fusion-positive non-small cell lung cancer. FDA. Updated November 7, 2022. Accessed April 1, 2024. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-disco-burst-edition-fda-approvals-retevmo-selpercatinib-adult-patients-locally-advanced-or

Subbiah V, Wolf J, Konda B, et al. Tumour-agnostic efficacy and safety of selpercatinib in patients with RET fusion-positive solid tumours other than lung or thyroid tumours (LIBRETTO-001): a phase 1/2, open-label, basket trial. 

. 2022;23(10):1261-1273. doi:10.1016/S1470-2045(22)00541-1

Li JJ, Rogers JE, Yamashita K, Waters RE, Blum Murphy M, Ajani JA. Therapeutic advances in the treatment of gastroesophageal cancers. 

. 2023;13(5):796. doi:10.3390/biom13050796

 gene locus encodes the protein CLAUDIN-18, a tight junction (TJ)protein and a member of the claudin family.

CLAUDIN18.2 (CLDN18.2) is a specific splice isoform of the claudin-18 protein and is expressed primarily in gastric epithelial cells, with minimal expression in other healthy tissues.

In healthy tissues, CLAUDIN proteins are localized at the apical region of the cell membrane, where they function within the TJ complex to promote cell adhesion; maintain cell polarity; and facilitate cell migration, matrix remodeling, and proliferation.

Under normal physiological conditions, CLDN18.2 is shielded from epitope exposure. However, during malignant cellular transformation, alterations in cell polarity result in the exposure of CLDN18.2 epitopes on the cell surface, making it a viable target for molecular therapy.

CLDN18.2 overexpression, defined as moderate-to-strong CLDN18.2 membrane staining in ≥75% of tumor cells, occurs in approximately 

 of gastric and gastroesophagealjunction (GEJ) cancers.

Altered CLDN18.2 expression can impair tight junction integrity, leading to increased permeability and facilitating processes like epithelial-mesenchymal transition (EMT), which enhances tumor invasiveness and metastatic potential.

CLDN18.2 has also been implicated in various oncogenic signaling pathways, including SPAK-p38 MAPK, EGFR-ERK, and protein kinase C.

Universal testing for microsatellite instability (MSI) status by polymerase chain reaction (PCR)/next-generation sequencing (NGS) or mismatch repair (MMR) status by immunohistochemistry (IHC) is recommended in all patients with newly diagnosed gastric or GEJ adenocarcinoma.

Human epidermal growth factor 2 (HER2), programmed death ligand 1 (PD-L1), and CLDN18.2 testing are recommended at the time of diagnosis if advanced/metastatic disease is documented or suspected.

Testing for CLDN18.2 should take place prior to the commencement of targeted therapy, as this will determine whether the patient is eligible for treatment with zolbetuximab.

IHC is the primary testing method used to evaluate CLDN18.2 status in tumor samples.

The Ventana CLDN18 (43-14A) RxDx IHC Assay is the FDA-approved companion diagnostic for detecting CLDN18.2 expression and was utilized in the SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) trials to identify patients for zolbetuximab therapy.

The NCCN recommends CLDN18.2 testing for patients for whom zolbetuximab is being considered.

IHC/ISH/targeted PCR are the preferred initial approaches to assessing biomarkers. However, NGS testing through a Clinical Laboratory Improvement Amendments–approved lab may be considered later in the clinical course for patients with sufficient tumor tissue available for testing.

One oral agent, zolbetuximab (Vyloy), has been approved and is the first monoclonal antibody directed against CLDN18.2.

Zolbetuximab is indicated for use in combination with fluoropyrimidine-and platinum-based chemotherapy for the treatment of adult patients with locally advanced, unresectable or metastatic CLDN18.2-positive, HER2-negative gastric or GEJ adenocarcinoma.

Zolbetuximab binds specifically to the extracellular domain of CLDN18.2, triggering antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).

Fassan M, Kuwata T, Matkowskyj KA, Röcken C, Rüschoff J. Claudin-18.2 immunohistochemical evaluation in gastric and gastroesophageal junction adenocarcinomas to direct targeted therapy: a practical approach. 

. 2024;37(11):100589. doi:10.1016/j.modpat.2024.100589

Cao W, Xing H, Li Y, et al. Claudin18.2 is a novel molecular biomarker for tumor-targeted immunotherapy. 

. 2022;10(1):38. doi:10.1186/s40364-022-00385-1

Mathias-Machado MC, de Jesus VHF, Jácome A, et al. Claudin 18.2 as a biomarker in gastric cancer—what should we know? 

. 2024;16(3):679. doi:10.3390/cancers16030679

Pellino A, Riello E, Nappo F, et al. Targeted therapies in metastatic gastric cancer: current knowledge and future perspectives. 

. 2019;25(38):5773-5788. doi:10.3748/wjg.v25.i38.5773

Hong JY, An JY, Lee J, et al. Claudin18.2 expression in various tumor types and its role as a potential target in advanced gastric cancer. 

 2020;9(5):3367-3374. doi:10.21037/tcr-19-1876

NCCN Clinical Practice Guidelines. Gastric cancer, version 1.2025. 

Vyloy (zolbetuximab-Clzb). Prescribing information. Astellas Pharma US, Inc; 2024. Accessed March 3, 2025. 

https://www.astellas.com/us/system/files/vyloy_pi.pdf

FDA Approves zolbetuximab-clzb with chemotherapy for gastric or gastroesophageal junction adenocarcinoma. FDA.gov. Updated October 18, 2024. Accessed March 3, 2025. 

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-zolbetuximab-clzb-chemotherapy-gastric-or-gastroesophageal-junction-adenocarcinoma

Shah MA, Shitara K, Ajani JA, et al. Zolbetuximab plus CAPOX in CLDN18.2-positive gastric or gastroesophageal junction adenocarcinoma: the randomized, phase 3 GLOW trial. 

. 2023;29(8):2133-2141. doi:10.1038/s41591-023-02465-7

Shitara K, Van Cutsem E, Lordick F, et al. Final overall survival results from phase 3 SPOTLIGHT study evaluating zolbetuximab + mFOLFOX6 as first-line (1L) treatment for patients (pts) with claudin 18 isoform 2 (CLDN18.2)+, HER2−, locally advanced (LA) unresectable or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma. 

. 2024;42(suppl 16):4036-4036. doi:10.1200/JCO.2024.42.16_suppl.4036

CLAUDIN18.2

Human epidermal growth factor receptor 2 (

); erb-b2 avian erythroblastic leukemia viral oncogene homolog 2 (

, is a proto-oncogene found on chromosome 17q12 that encodes a transmembrane tyrosine kinase receptor belonging to the epidermal growth factor receptor family.

When activated following phosphorylation, the HER2 receptor triggers signaling pathways associated with cell division, proliferation, differentiation, and anti-apoptosis. 

of gastroesophageal adenocarcinomas (GEAs) exhibit HER2 amplification or overexpression

Overexpression rates are slightly higher in cancers at the gastroesophageal junction compared to those in the stomach, with variations based on histologic type and differentiation.

Gastric Cancer

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