Activity of Tepotinib in Hepatocellular Carcinoma With High-Level MET Amplification: Preclinical and Clinical Evidence.

PURPOSE: MET amplification (METamp) has been reported in 1%-5% of patients with hepatocellular carcinoma (HCC) and may be sensitive to MET inhibition. Tepotinib, a selective MET inhibitor, has shown promising activity in HCC with MET overexpression. We investigated the preclinical and clinical activity of tepotinib in HCC with METamp (MET gene copy number [GCN] ≥5), including high-level METamp (MET GCN ≥10). METHODS: Preclinical antitumor activity of tepotinib 100 mg/kg (orally, days 1-5, every 7 days, 3-5 weeks; 3-12 replicates) was evaluated according to METamp status, as determined using the nCounter platform (NanoString), in 37 HCC patient-derived xenografts (PDXs) in immunodeficient mice. Clinical outcomes were evaluated in patients with METamp by fluorescence in situ hybridization who received tepotinib 500 mg (450 mg active moiety) in two phase Ib/II trials in HCC with MET overexpression. RESULTS: Across the PDX models, tepotinib induced complete or near-complete tumor regression in the only two models with high-level METamp. Median tumor volume reductions were 100% and 99.8% in models with MET GCN 47.1 and 44.0, respectively. Across the two clinical trials, 15/121 patients had METamp. Disease control was achieved by 11/15 patients with METamp (complete response [CR], n = 1; partial response [PR], n = 4; stable disease [SD], n = 6) and 4/4 with high-level METamp (CR, n = 1; PR, n = 2; SD, n = 1). All three patients with high-level METamp and objective response received treatment for >1 year, including one patient who received first-line tepotinib for >6 years. CONCLUSION: High-level METamp may be an oncogenic driver in HCC that is sensitive to MET inhibitors such as tepotinib.

Tepotinib in patients with non-small cell lung cancer with high-level MET amplification detected by liquid biopsy: VISION Cohort B.

High-level MET amplification (METamp) is a primary driver in ∼1%-2% of non-small cell lung cancers (NSCLCs). Cohort B of the phase 2 VISION trial evaluates tepotinib, an oral MET inhibitor, in patients with advanced NSCLC with high-level METamp who were enrolled by liquid biopsy. While the study was halted before the enrollment of the planned 60 patients, the results of 24 enrolled patients are presented here. The objective response rate (ORR) is 41.7% (95% confidence interval [CI], 22.1-63.4), and the median duration of response is 14.3 months (95% CI, 2.8-not estimable). In exploratory biomarker analyses, focal METamp, RB1 wild-type, MYC diploidy, low circulating tumor DNA (ctDNA) burden at baseline, and early molecular response are associated with better outcomes. Adverse events include edema (composite term; any grade: 58.3%; grade 3: 12.5%) and constipation (any grade: 41.7%; grade 3: 4.2%). Tepotinib provides antitumor activity in high-level METamp NSCLC (ClinicalTrials.gov: NCT02864992).

Immunological and tumor-intrinsic mechanisms mediate the synergistic growth suppression of experimental glioblastoma by radiotherapy and MET inhibition.

The hepatocyte growth factor (HGF)/MET signaling pathway has been proposed to be involved in the resistance to radiotherapy of glioblastoma via proinvasive and DNA damage response pathways.Here we assessed the role of the MET pathway in the response to radiotherapy in vitro and in vivo in syngeneic mouse glioma models. We find that the murine glioma cell lines GL-261, SMA-497, SMA-540 and SMA-560 express HGF and its receptor MET and respond to exogenous HGF with MET phosphorylation. Glioma cell viability or proliferation are unaffected by genetic or pharmacological MET inhibition using tepotinib or CRISPR/Cas9-engineered Met gene knockout and MET inhibition fails to sensitize glioma cells to irradiation in vitro. In contrast, the combination of tepotinib with radiotherapy prolongs survival of orthotopic SMA-560 or GL-261 glioma-bearing mice compared with radiotherapy or tepotinib treatment alone. Synergy is lost when such experiments are conducted in immunodeficient Rag1-/- mice, and, importantly, also when Met gene expression is disrupted in the tumor cells. Combination therapy suppresses a set of pro-inflammatory mediators including matrix metalloproteases that are upregulated by radiotherapy alone and that have been linked to poor outcome in glioblastoma. Several of these mediators are positively regulated by transforming growth factor (TGF)-ß, and pSMAD2 levels as a surrogate marker of TGF-ß pathway activity are suppressed by combination treatment. We conclude that synergistic suppression of experimental syngeneic glioma growth by irradiation and MET inhibition requires MET expression in the tumor as well as an intact immune system. Clinical evaluation of this combined strategy in newly diagnosed glioblastoma is warranted.

The Preclinical Pharmacology of Tepotinib-A Highly Selective MET Inhibitor with Activity in Tumors Harboring MET Alterations.

The mesenchymal-epithelial transition factor (MET) proto-oncogene encodes the MET receptor tyrosine kinase. MET aberrations drive tumorigenesis in several cancer types through a variety of molecular mechanisms, including MET mutations, gene amplification, rearrangement, and overexpression. Therefore, MET is a therapeutic target and the selective type Ib MET inhibitor, tepotinib, was designed to potently inhibit MET kinase activity. In vitro, tepotinib inhibits MET in a concentration-dependent manner irrespective of the mode of MET activation, and in vivo, tepotinib exhibits marked, dose-dependent antitumor activity in MET-dependent tumor models of various cancer indications. Tepotinib penetrates the blood-brain barrier and demonstrates strong antitumor activity in subcutaneous and orthotopic brain metastasis models, in-line with clinical activity observed in patients. MET amplification is an established mechanism of resistance to EGFR tyrosine kinase inhibitors (TKI), and preclinical studies show that tepotinib in combination with EGFR TKIs can overcome this resistance. Tepotinib is currently approved for the treatment of adult patients with advanced or metastatic non-small cell lung cancer harboring MET exon 14 skipping alterations. This review focuses on the pharmacology of tepotinib in preclinical cancer models harboring MET alterations and demonstrates that strong adherence to the principles of the Pharmacological Audit Trail may result in a successful discovery and development of a precision medicine.

Brain penetration and efficacy of tepotinib in orthotopic patient-derived xenograft models of MET-driven non-small cell lung cancer brain metastases.

Central nervous system-penetrant therapies with intracranial efficacy against non-small cell lung cancer (NSCLC) brain metastases are urgently needed. We report preclinical studies investigating brain penetration and intracranial activity of the MET inhibitor tepotinib. After intravenous infusion of tepotinib in Wistar rats (n = 3), mean (±standard deviation) total tepotinib concentration was 2.87-fold higher in brain (505 ± 22 ng/g) than plasma (177 ± 20 ng/mL). In equilibrium dialysis experiments performed in triplicate, mean tepotinib unbound fraction was 0.35% at 0.3 and 3.0 µM tepotinib in rat brain tissue, and 4.0% at 0.3 and 1.0 µM tepotinib in rat plasma. The calculated unbound brain-to-plasma ratio was 0.25, indicating brain penetration sufficient for intracranial target inhibition. Of 20 screened subcutaneous patient-derived xenograft (PDX) models from lung cancer brain metastases (n = 1), two NSCLC brain metastases models (LU5349 and LU5406) were sensitive to the suboptimal dose of tepotinib of 30 mg/kg/qd (tumor volume change [%TV]: -12% and -88%, respectively). Molecular profiling (nCounter®; NanoString) revealed high-level MET amplification in both tumors (mean MET gene copy number: 11.2 and 24.2, respectively). Tepotinib sensitivity was confirmed for both subcutaneous models at a clinically relevant dose (125 mg/kg/qd; n = 5). LU5349 and LU5406 were orthotopically implanted into brains of mice and monitored by magnetic resonance imaging (MRI). Tepotinib 125 mg/kg/qd induced pronounced tumor regression, including complete or near-complete regressions, compared with vehicle in both orthotopic models (n = 10; median %TV: LU5349, -84%; LU5406, -63%). Intracranial antitumor activity of tepotinib did not appear to correlate with blood-brain barrier leakiness assessed in T1-weighted gadolinium contrast-enhanced MRI.

Landscape and Clonal Dominance of Co-occurring Genomic Alterations in Non-Small-Cell Lung Cancer Harboring MET Exon 14 Skipping.

MET exon 14 skipping alterations (METex14) comprise a diverse set of actionable oncogene drivers in non-small-cell lung cancer (NSCLC). Recent studies have established the efficacy of tyrosine kinase inhibitors for this patient population. The landscape of co-occurring genetic alterations in METex14 NSCLC and their potential impact to therapeutic sensitivities has not yet been fully described. MATERIALS AND METHODS: METex14 NSCLC cases were collected from three cohorts: the VISION trial, and data sets from Guardant360 and GenePlus. Clinicopathologic characteristics and METex14 mutation sites were analyzed and compared across data sets. Co-occurring genetic alterations and the clonality relationships to METex14 were evaluated. RESULTS: Of 40,824 NSCLCs, 692 METex14 cases (1.7%) were identified, including 332 in Guardant360, 188 in VISION, and 172 in GenePlus. The demographics and mutation type and/or sites were similar in the Asian versus Western cohorts. MET amplification, which were found to be associated with sensitivity to MET kinase inhibitors, co-occurs in 7.6%-13.8% of cases, whereas kinase domain secondary mutation of MET co-occurs in 5%-6%. When co-occurring with METex14, EGFR mutations were often identified as the dominant clone (78%, 7 of 9), whereas when co-occurring, METex14 (39%, 7 of 18) and KRAS (44%, 8 of 18) had similar rates of clonal dominance. PIK3CA and PTEN mutations were almost always subclones (89%, 16 of 18) to METex14. Moreover, RET-CCDC6 fusion and EGFR mutation were detected following crizotinib treatment in two patients, suggesting novel mechanisms of resistance. CONCLUSION: METex14 mutations frequently co-occur with other potential driver oncogenes with differing patterns of clonal dominance observed among the drivers. This cellular context can provide insights into whether METex14 is acting as a primary oncogenic driver or resistance mechanism and help guide treatment choices.

Real-world insights into patients with advanced NSCLC and MET alterations.

OBJECTIVES: To describe characteristics, treatment and outcomes of non-small cell lung cancer (NSCLC) patients with MET alterations (MET exon 14 [METex14] skipping or MET amplification [METamp]) in real-world clinical care. METHODS: This non-interventional cohort study used real-world data extracted from electronic medical records from academic oncology sites in Israel, The Netherlands, Taiwan, and the USA. Patients had confirmed diagnosis of advanced (Stage IIIB-IV) NSCLC harboring MET alterations (date of diagnosis = index date) between 1 Jan 2010 and 30 Sept 2018. Medical history was assessed prior to and at the index date (baseline period), and outcomes from first date of treatment to death, loss to follow-up, or end of study period. RESULTS: A total of 117 patients were included (METex14 n = 70; METamp n = 47); testing methods were heterogeneous. Concomitant oncogenic mutations were more common in the METamp cohort than METex14. Patients in the METex14 cohort were older than those in METamp, and a larger proportion were never smokers. Anticancer first-line therapies received by patients (METex14; METamp) included chemotherapy only (44%; 41%), MET inhibitors (33%; 29%), immune checkpoint inhibitor (ICI) mono-(12%; 15%) and combination-therapy (8%; 3%). Second-line therapies included chemotherapy (35%; 30%) and MET inhibitors (30%; 39%). In the METex14 cohort, objective response rate (ORR) was generally low (first-line 28%; second-line 30%); no patients who received ICIs had a response. In the METamp cohort, ORR was 36% in first-line and 22% in second-line. Median (95% confidence interval) overall survival from start of first-line therapy was 12.0 months (6.8, 19.2) in the METex14 cohort and 22.0 months (9.8, 31.2) in METamp. CONCLUSIONS: Heterogeneous treatments reflect the changing landscape and availability of new treatments, as well as the high unmet medical need in older, METex14 patients who had more advanced disease at diagnosis. MET-targeted therapies could be beneficial in patients with these rare MET alterations.

Translational pharmacokinetic-pharmacodynamic modeling of preclinical and clinical data of the oral MET inhibitor tepotinib to determine the recommended phase II dose.

Tepotinib is a highly selective and potent MET inhibitor in development for the treatment of patients with solid tumors. Given the favorable tolerability and safety profiles up to the maximum tested dose in the first-in-human (FIH) trial, an efficacy-driven translational modeling approach was proposed to establish the recommended phase II dose (RP2D). To study the in vivo pharmacokinetics (PKs)/target inhibition/tumor growth inhibition relationship, a subcutaneous KP-4 pancreatic cell-line xenograft model in mice with sensitivity to MET pathway inhibition was selected as a surrogate tumor model. Further clinical PK and target inhibition data (derived from predose and postdose paired tumor biopsies) from a FIH study were integrated with the longitudinal PKs and target inhibition profiles from the mouse xenograft study to establish a translational PK/pharmacodynamic (PD) model. Preclinical data showed that tumor regression with tepotinib treatment in KP-4 xenograft tumors corresponded to 95% target inhibition. We therefore concluded that a PD criterion of sustained, near-to-complete (>95%) phospho-MET inhibition in tumors should be targeted for tepotinib to be effective. Simulations of dose-dependent target inhibition profiles in human tumors that exceeded the PD threshold in more than 90% of patients established an RP2D of tepotinib 500 mg once daily. This translational mathematical modeling approach supports an efficacy-driven rationale for tepotinib phase II dose selection of 500 mg once daily. Tepotinib at this dose has obtained regulatory approval for the treatment of patients with non-small cell lung cancer harboring MET exon 14 skipping.

SHP2 Inhibition Influences Therapeutic Response to Tepotinib in Tumors with MET Alterations.

Tepotinib is an oral MET inhibitor approved for metastatic non-small cell lung cancer (NSCLC) harboring MET exon 14 (METex14) skipping mutations. Examining treatment-naive or tepotinib-resistant cells with MET amplification or METex14 skipping mutations identifies other receptor tyrosine kinases (RTKs) that co-exist in cells prior to tepotinib exposure and become more prominent upon tepotinib resistance. In a small cohort of patients with lung cancer with MET genetic alterations treated with tepotinib, gene copy number gains of other RTKs were found at baseline and affected treatment outcome. An Src homology 2 domain-containing phosphatase 2 (SHP2) inhibitor delayed the emergence of tepotinib resistance and synergized with tepotinib in treatment-naive and tepotinib-resistant cells as well as in xenograft models. Alternative signaling pathways potentially diminish the effect of tepotinib monotherapy, and the combination of tepotinib with an SHP2 inhibitor enables the control of tumor growth in cells with MET genetic alterations.

Cetuximab-Mediated Protection from Hypoxia- Induced Cell Death: Implications for Therapy Sequence in Colorectal Cancer.

Monoclonal antibodies like cetuximab, targeting the epidermal growth factor receptor (EGFR), and bevacizumab, targeting the vascular endothelial growth factor (VEGF), are an integral part of treatment regimens for metastasized colorectal cancer. However, inhibition of the EGFR has been shown to protect human glioma cells from cell death under hypoxic conditions. In colon carcinoma cells, the consequences of EGFR blockade in hypoxia (e.g., induced by bevacizumab) have not been evaluated yet. LIM1215 and SW948 colon carcinoma and LNT-229 glioblastoma cells were treated with cetuximab, PD153035, and erlotinib and analyzed for cell density and viability. The sequential administration of either cetuximab followed by bevacizumab (CET->BEV) or bevacizumab followed by cetuximab (BEV->CET) was investigated in a LIM1215 (KRAS wildtype) and SW948 (KRAS mutant) xenograft mouse model. In vitro, cetuximab protected from hypoxia. In the LIM1215 model, a survival benefit with cetuximab and bevacizumab monotherapy was observed, but only the sequence CET->BEV showed an additional benefit. This effect was confirmed in the SW948 model. Our observations support the hypothesis that bevacizumab modulates the tumor microenvironment (e.g., by inducing hypoxia) where cetuximab could trigger protective effects when administered later on. The sequence CET->BEV therefore seems to be superior as possible mutual adverse effects are bypassed.

Tepotinib in Non-Small-Cell Lung Cancer with MET Exon 14 Skipping Mutations.

BACKGROUND: A splice-site mutation that results in a loss of transcription of exon 14 in the oncogenic driver MET occurs in 3 to 4% of patients with non-small-cell lung cancer (NSCLC). We evaluated the efficacy and safety of tepotinib, a highly selective MET inhibitor, in this patient population. METHODS: In this open-label, phase 2 study, we administered tepotinib (at a dose of 500 mg) once daily in patients with advanced or metastatic NSCLC with a confirmed MET exon 14 skipping mutation. The primary end point was the objective response by independent review among patients who had undergone at least 9 months of follow-up. The response was also analyzed according to whether the presence of a MET exon 14 skipping mutation was detected on liquid biopsy or tissue biopsy. RESULTS: As of January 1, 2020, a total of 152 patients had received tepotinib, and 99 patients had been followed for at least 9 months. The response rate by independent review was 46% (95% confidence interval [CI], 36 to 57), with a median duration of response of 11.1 months (95% CI, 7.2 to could not be estimated) in the combined-biopsy group. The response rate was 48% (95% CI, 36 to 61) among 66 patients in the liquid-biopsy group and 50% (95% CI, 37 to 63) among 60 patients in the tissue-biopsy group; 27 patients had positive results according to both methods. The investigator-assessed response rate was 56% (95% CI, 45 to 66) and was similar regardless of the previous therapy received for advanced or metastatic disease. Adverse events of grade 3 or higher that were considered by investigators to be related to tepotinib therapy were reported in 28% of the patients, including peripheral edema in 7%. Adverse events led to permanent discontinuation of tepotinib in 11% of the patients. A molecular response, as measured in circulating free DNA, was observed in 67% of the patients with matched liquid-biopsy samples at baseline and during treatment. CONCLUSIONS: Among patients with advanced NSCLC with a confirmed MET exon 14 skipping mutation, the use of tepotinib was associated with a partial response in approximately half the patients. Peripheral edema was the main toxic effect of grade 3 or higher. (Funded by Merck [Darmstadt, Germany]; VISION ClinicalTrials.gov number, NCT02864992.).

The promise of selective MET inhibitors in non-small cell lung cancer with MET exon 14 skipping.

Dysregulated activation of the MET tyrosine kinase receptor is implicated in the development of solid tumors and can arise through several mechanisms, including gene amplification, overexpression of the receptor and/or its ligand hepatocyte growth factor (HGF), and the acquisition of activating mutations. The most common activating mutations cause exon 14 to be skipped during MET mRNA splicing. This in-frame deletion, known as MET exon 14, results in production of a shortened receptor that lacks a juxtamembrane domain but retains affinity for HGF. However, the negative regulatory function located within this protein sequence is lost, leading to receptor accumulation on the cell surface and prolonged activation by HGF. MET mutations causing exon 14 skipping appear to be true oncogenic drivers and occur in patients and tumors with distinct characteristics. Increasing evidence suggests that tumors carrying such mutations are sensitive to MET inhibition, raising the hope that selective MET inhibitors will provide patients with optimal anticancer activity with minimal toxicity. We discuss the prospects for selective MET inhibitors in the treatment of non-small cell lung cancer harboring MET exon 14 skipping.

Targeting the MET Receptor Tyrosine Kinase as a Strategy for Radiosensitization in Locoregionally Advanced Head and Neck Squamous Cell Carcinoma.

Radiotherapy (RT) along with surgery is the mainstay of treatment in head and neck squamous cell carcinoma (HNSCC). Radioresistance represents a major source of treatment failure, underlining the urgent necessity to explore and implement effective radiosensitization strategies. The MET receptor widely participates in the acquisition and maintenance of an aggressive phenotype in HNSCC and modulates the DNA damage response following ionizing radiation (IR). Here, we assessed MET expression and mutation status in primary and metastatic lesions within a cohort of patients with advanced HNSCC. Moreover, we investigated the radiosensitization potential of the MET inhibitor tepotinib in a panel of cell lines, in vitro and in vivo, as well as in ex vivo patient-derived organotypic tissue cultures (OTC). MET was highly expressed in 62.4% of primary tumors and in 53.6% of lymph node metastases (LNM), and in 6 of 9 evaluated cell lines. MET expression in primaries and LNMs was significantly associated with decreased disease control in univariate survival analyses. Tepotinib abrogated MET phosphorylation and to distinct extent MET downstream signaling. Pretreatment with tepotinib resulted in variable radiosensitization, enhanced DNA damage, cell death, and G2-M-phase arrest. Combination of tepotinib with IR led to significant radiosensitization in one of two tested in vivo models. OTCs revealed differential patterns of response toward tepotinib, irradiation, and combination of both modalities. The molecular basis of tepotinib-mediated radiosensitization was studied by a CyTOF-based single-cell mass cytometry approach, which uncovered that MET inhibition modulated PI3K activity in cells radiosensitized by tepotinib but not in the resistant ones.

The First-in-class Anti-EGFR Antibody Mixture Sym004 Overcomes Cetuximab Resistance Mediated by EGFR Extracellular Domain Mutations in Colorectal Cancer.

PURPOSE: Approved anti-EGFR antibodies cetuximab and panitumumab provide significant clinical benefit in patients with metastatic colorectal cancer (MCRC). However, patients ultimately develop disease progression, often driven by acquisition of mutations in the extracellular domain (ECD) of EGFR. Sym004 is a novel 1:1 mixture of two nonoverlapping anti-EGFR mAbs that recently showed promising clinical activity in a phase I trial in MCRC. Our aim was to determine the efficacy of Sym004 to circumvent cetuximab resistance driven by EGFR ECD mutations. EXPERIMENTAL DESIGN: Functional studies were performed to assess drug-receptor binding as well as ligand-dependent activation of individual EGFR mutants in the presence of cetuximab, panitumumab, and Sym004. Cell viability and molecular effects of the drugs were assayed in cetuximab-resistant cell lines and in tumor xenograft models. Efficacy of Sym004 was evaluated in patients progressing to cetuximab that harbored EGFR mutation in the post-cetuximab tumor sample. RESULTS: Contrary to cetuximab and panitumumab, Sym004 effectively bound and abrogated ligand-induced phosphorylation of all individual EGFR mutants. Cells resistant to cetuximab harboring mutations in EGFR maintained sensitivity to Sym004, which was consistent with an effective suppression of EGFR downstream signaling, translating into profound and sustained tumor regression in the xenograft model. As proof-of-principle, a patient with a tumor harboring an EGFR mutation (G465R) following cetuximab therapy benefited from Sym004 therapy. CONCLUSIONS: Sym004 is an active drug in MCRC resistant to cetuximab/panitumumab mediated by EGFR mutations. EGFR mutations are potential biomarkers of response to Sym004 to be evaluated in ongoing large clinical trials. Clin Cancer Res; 22(13); 3260-7. ©2016 AACR.

Fluorouracil, leucovorin, and irinotecan plus cetuximab treatment and RAS mutations in colorectal cancer.

PURPOSE: The phase III CRYSTAL study demonstrated that addition of cetuximab to fluorouracil, leucovorin, and irinotecan (FOLFIRI) significantly improved overall survival, progression-free survival, and objective response in the first-line treatment of patients with KRAS codon 12/13 (exon 2) wild-type metastatic colorectal cancer (mCRC). Outcome was reassessed in subgroups defined by extended RAS mutation testing. PATIENTS AND METHODS: Existing DNA samples from KRAS exon 2 wild-type tumors from CRYSTAL study patients were reanalyzed for other RAS mutations in four additional KRAS codons (exons 3 and 4) and six NRAS codons (exons 2, 3, and 4) using beads, emulsion, amplification, and magnetics technology. No tissue microdissection was performed. A ≥ 5% mutant allele cutoff was used to call mutations. RESULTS: Mutation status was evaluable in 430 (64.6%) of 666 patients with KRAS exon 2 wild-type tumors. Other RAS mutations were detected in 63 (14.7%) of 430 patients. In those with RAS wild-type tumors, a significant benefit across all efficacy end points was associated with the addition of cetuximab to FOLFIRI. In patients with other RAS tumor mutations, no difference in efficacy outcomes between treatment groups was seen. The safety profile in RAS subgroups was similar and in line with expectations. CONCLUSION: In the first-line treatment of mCRC, patients with RAS wild-type tumors derived a significant benefit from the addition of cetuximab to FOLFIRI; patients with RAS tumor mutations did not. Molecular testing of tumors for all activating RAS mutations is essential before considering anti-epidermal growth factor receptor therapy, thereby allowing the further tailoring of cetuximab administration to maximize patient benefit.

IgG1 anti-epidermal growth factor receptor antibodies induce CD8-dependent antitumor activity.

Anti-EGFR monoclonal antibodies (mAb) like Cetuximab are commonly used for treatment of EGFR+ solid tumors mainly by exerting their therapeutic effect through inhibition of signal transduction. Additionally, IgG1 is a potent mediator of antibody-dependent cytotoxicity (ADCC). In case of the IgG1, Cetuximab induction of ADCC in vivo is controversially discussed. In our study, we investigated the efficiency of Cetuximab-mediated ADCC in a humanized mouse tumor model in vivo and analyzed the contribution of immunologic processes toward antitumor activity. Therefore, we used immunodeficient NOD/Scid mice transgenic for human MHC class I molecule HLA-A2 and adoptively transferred human HLA-A2+ PBMC after engraftment of human epidermoid cell carcinoma A431. Here, we show that high doses of anti-EGFR mAb induced strong tumor regression independent of the immune system. However, tumor regression by low doses of anti-EGFR mAb treatment was ADCC dependent and mediated by tumor infiltrating CD8+ T effector cells. This novel mechanism of ADCC conducted by CD8+ T effector cells was restricted to IgG1 anti-EGFR mAb, dependent of binding to CD16 on T cells and could be inhibited after EGFR blockade on tumor cells. Furthermore, CD8+ T effector cell-mediated ADCC was enhanced in the presence of IL-15 and strongly improved after glycosylation of anti-EGFR mAb indicating the potential of glycoengineered therapeutic mAb as efficient biologicals in cancer therapy.

Association of EGFR expression level and cetuximab activity in patient-derived xenograft models of human non-small cell lung cancer.

PURPOSE: To explore in a panel of patient-derived xenograft models of human non-small cell lung cancer (NSCLC) whether high EGFR expression, was associated with cetuximab activity. EXPERIMENTAL DESIGN: NSCLC patient-derived xenograft models (n=45) were implanted subcutaneously into panels of nude mice and randomization cohorts were treated with either cetuximab, cisplatin, cisplatin plus cetuximab, vehicle control, or else were left untreated. Responses according to treatment were assessed at week 3 by analyzing the relative change in tumor volume and an experimental analogue of the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines. An EGFR IHC score was calculated for each patient-derived xenograft model and response was assessed according to EGFR expression level. RESULTS: When tumors were stratified into high and low EGFR expression groups (IHC score threshold 200; scale 0-300), a stronger antitumor activity was seen in the high EGFR expression group compared with the low EGFR expression group in both the cetuximab monotherapy and cisplatin plus cetuximab combination therapy settings. For tumors treated with cisplatin plus cetuximab, the objective response rate was significantly higher in the high EGFR expression group compared with the low EGFR expression group (68% vs. 29%). Objective response rates were similar in high and low expression groups for tumors treated with cisplatin alone (27% vs. 24%, respectively). CONCLUSION: Cetuximab activity in NSCLC patient-derived xenograft models was demonstrated clearly only in tumors that expressed high levels of EGFR, as defined by an IHC score of ≥200.

Molecular biomarkers in non-small-cell lung cancer: a retrospective analysis of data from the phase 3 FLEX study.

BACKGROUND: Findings from the phase 3 FLEX study showed that the addition of cetuximab to cisplatin and vinorelbine significantly improved overall survival, compared with cisplatin and vinorelbine alone, in the first-line treatment of EGFR-expressing, advanced non-small-cell lung cancer (NSCLC). We investigated whether candidate biomarkers were predictive for the efficacy of chemotherapy plus cetuximab in this setting. METHODS: Genomic DNA extracted from formalin-fixed paraffin-embedded (FFPE) tumour tissue of patients enrolled in the FLEX study was screened for KRAS codon 12 and 13 and EGFR kinase domain mutations with PCR-based assays. In FFPE tissue sections, EGFR copy number was assessed by dual-colour fluorescence in-situ hybridisation and PTEN expression by immunohistochemistry. Treatment outcome was investigated according to biomarker status in all available samples from patients in the intention-to-treat population. The primary endpoint in the FLEX study was overall survival. The FLEX study, which is ongoing but not recruiting participants, is registered with ClinicalTrials.gov, number NCT00148798. FINDINGS: KRAS mutations were detected in 75 of 395 (19%) tumours and activating EGFR mutations in 64 of 436 (15%). EGFR copy number was scored as increased in 102 of 279 (37%) tumours and PTEN expression as negative in 107 of 303 (35%). Comparisons of treatment outcome between the two groups (chemotherapy plus cetuximab vs chemotherapy alone) according to biomarker status provided no indication that these biomarkers were of predictive value. Activating EGFR mutations were identified as indicators of good prognosis, with patients in both treatment groups whose tumours carried such mutations having improved survival compared with those whose tumours did not (chemotherapy plus cetuximab: median 17·5 months [95% CI 11·7-23·4] vs 8·5 months [7·1-10·8], hazard ratio [HR] 0·52 [0·32-0·84], p=0·0063; chemotherapy alone: 23·8 months [15·2-not reached] vs 10·0 months [8·7-11·0], HR 0·35 [0·21-0·59], p<0·0001). Expression of PTEN seemed to be a potential indicator of good prognosis, with patients whose tumours expressed PTEN having improved survival compared with those whose tumours did not, although this finding was not significant (chemotherapy plus cetuximab: median 11·4 months [8·6-13·6] vs 6·8 months [5·9-12·7], HR 0·80 [0·55-1·16], p=0·24; chemotherapy alone: 11·0 months [9·2-12·6] vs 9·3 months [7·6-11·9], HR 0·77 [0·54-1·10], p=0·16). INTERPRETATION: The efficacy of chemotherapy plus cetuximab in the first-line treatment of advanced NSCLC seems to be independent of each of the biomarkers assessed. FUNDING: Merck KGaA.

Pharmacogenomic and pharmacoproteomic studies of cetuximab in metastatic colorectal cancer: biomarker analysis of a phase I dose-escalation study.

PURPOSE: This study assessed biomarkers for cetuximab efficacy in tissue samples collected during a phase I dose-escalation study exploring every second week administration of cetuximab as first-line therapy in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: Sixty-two patients received cetuximab monotherapy for 6 weeks, followed by cetuximab plus infusional fluorouracil, leucovorin, and irinotecan until disease progression. Patients in the control arm received cetuximab as a 400 mg/m(2) initial dose then 250 mg/m(2) per week; patients in the dose-escalation arms received 400 to 700 mg/m(2) every second week. Tumor and skin biopsies were taken for immunohistochemical and microarray expression analyses (tumor only) at baseline and week 4. Plasma was collected for proteomic analysis at baseline and week 4. KRAS tumor mutation status was assessed. RESULTS: In subsets of paired skin samples from 35 patients, cetuximab treatment was associated with substantial downregulation of phospho(p)-EGFR, p-MAPK and proliferation and substantial upregulation of p27(Kip1) and p-STAT3 levels. No marked difference in these effects was noted for different schedules of administration and dose levels. In the cetuximab monotherapy phase, responses were seen only in patients whose tumors were wild-type for KRAS (eight of 29 v zero of 19 for KRAS mutant tumors; P = .015). Progression-free survival was longer for patients with KRAS wild-type compared with KRAS mutant tumors (log-rank P = .048). Genomics/proteomics analyses (42 and 45 patients, respectively) identified candidate biomarkers associated with response. CONCLUSION: Biomarker analysis supported the functional equivalence of weekly and every second week administration of cetuximab and provided further confirmation that patients with KRAS wild-type mCRC were those most likely to benefit from cetuximab treatment.

Cetuximab and chemotherapy as initial treatment for metastatic colorectal cancer.

BACKGROUND: We investigated the efficacy of cetuximab plus irinotecan, fluorouracil, and leucovorin (FOLFIRI) as first-line treatment for metastatic colorectal cancer and sought associations between the mutation status of the KRAS gene in tumors and clinical response to cetuximab. METHODS: We randomly assigned patients with epidermal growth factor receptor-positive colorectal cancer with unresectable metastases to receive FOLFIRI either alone or in combination with cetuximab. The primary end point was progression-free survival. RESULTS: A total of 599 patients received cetuximab plus FOLFIRI, and 599 received FOLFIRI alone. The hazard ratio for progression-free survival in the cetuximab-FOLFIRI group as compared with the FOLFIRI group was 0.85 (95% confidence interval [CI], 0.72 to 0.99; P=0.048). There was no significant difference in the overall survival between the two treatment groups (hazard ratio, 0.93; 95% CI, 0.81 to 1.07; P=0.31). There was a significant interaction between treatment group and KRAS mutation status for tumor response (P=0.03) but not for progression-free survival (P=0.07) or overall survival (P=0.44). The hazard ratio for progression-free survival among patients with wild-type-KRAS tumors was 0.68 (95% CI, 0.50 to 0.94), in favor of the cetuximab-FOLFIRI group. The following grade 3 or 4 adverse events were more frequent with cetuximab plus FOLFIRI than with FOLFIRI alone: skin reactions (which were grade 3 only) (in 19.7% vs. 0.2% of patients, P<0.001), infusion-related reactions (in 2.5% vs. 0%, P<0.001), and diarrhea (in 15.7% vs. 10.5%, P=0.008). CONCLUSIONS: First-line treatment with cetuximab plus FOLFIRI, as compared with FOLFIRI alone, reduced the risk of progression of metastatic colorectal cancer. The benefit of cetuximab was limited to patients with KRAS wild-type tumors. (ClinicalTrials.gov number, NCT00154102.)