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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.

Supplementary Table 1 shows HNSCC patients' characteristics

Supplementary figure 1 provides data concerning establishment of organotypic tissue cultures from freshly-resected HNSCC specimen Supplementary figure 2 shows analyses of MET expression and mutational status in a HNSCC cohort Supplementary figure 3 shows impact of MET inhibition by tepotinib in HNSCC cell lines in vitro Supplementary figure 4 shows effects of combined treatment by tepotinib and ionizing radiation on HNSCC cell lines Supplementary figure 5 shows analyses of OTCs responses to treatment by tepotinib combined with ionizing radiation Supplementary figure 6 shows results of assays studying mechanisms underlying tepotinib-mediated radiosensitization of HNSCC cell lines

Supplementary Methods

Supplementary Table 2 provides odds ratio per protein (CyTOF measurements)

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.

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. Clin Cancer Res; 20(17); 4478–87. ©2014 AACR.

Figure S1: EGFR mutants binding to CTX, Sym004, PNM Figure S2: Clonogenic assay in EGFR mutants with CTX, Sym004, PNM

Table S2. Mann-Whitney test P-values relating to the differences in log2 tumor/control ratios at week 3 for cetuximab monotherapy/control and cisplatin plus cetuximab/cisplatin alone between tumors with low and high EGFR expression as determined by different EGFR immunohistochemistry score thresholds.

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 anti-tumor 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 (TKIs) 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 METex14 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.

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.

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.

PURPOSE 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.

Background: Although advancements have been made in available targeted therapies for non-small cell lung cancer (NSCLC), most patients have an incomplete response and eventually acquire resistance. It is well known that MET signaling is a key pathway that mediates osimertinib resistance. Concurrently targeting multiple proteins in critical signaling pathways, including the MET receptor or SHP2, a key node downstream of receptor tyrosine kinases, may prevent or delay resistance. Here, we explore the promising concept of combining upfront targeted therapies with a selective MET inhibitor or SHP2 inhibitor as promising therapeutic strategies for oncogene-driven NSCLC. Methods: All cell lines were obtained from commercial vendors. Drugs were synthesized at Merck KGaA or purchased from commercial vendors. Cell viability upon inhibitor treatment was investigated by Resazurin Cell Viability Assay (R&D Systems), and the effect of the inhibitors on colony forming ability was assessed using colony formation assays. Western blot was conducted to analyze pathway activity. The emergence of resistance was investigated by measuring the cell surface confluence using the IncuCyte S3 system (Essen Bioscience). Results: The lung cancer cell lines used were NCI-H358 (KRAS G12C), HCC-827 (EGFR L858R), NCI-H2228 (ALK fusion), HCC-78 (ROS1 fusion), and NCI-H1781 (HER2 exon 20 insertion), with their respective targeted therapies sotorasib, osimertinib, alectinib, entrectinib, and poziotinib. The antiproliferative effects of targeted therapies combined with a MET or SHP2 inhibitor were assessed using combination dose matrices in 6-day viability assays. While MET inhibition did not further sensitize the already sensitive cells to the targeted therapies, synergism occurred when the drugs were combined with the SHP2 inhibitor. Similar results were obtained by colony formation assays lasting 2 weeks. Furthermore, the combination of the targeted therapies with the SHP2 inhibitor led to stronger ERK signaling abrogation than with single therapies. In a long-term proliferation assay, the combined inhibition of EGFR and MET receptor delayed the emergence of osimertinib resistance in the EGFR mutant HCC827 cells, which have MET protein overexpression and phosphorylation. Conclusions: Our data show that combining targeted therapies with a SHP2 inhibitor synergistically decreases the viability of oncogene-driven NSCLC cell lines, indicating that initial combination therapy may be an appealing approach to improve patient outcomes. The observed delay in the emergence of osimertinib resistance, from combining a MET inhibitor with osimertinib, provides preclinical evidence to support further investigating MET inhibition upfront to improve the long-term therapeutic efficacy of EGFR inhibitors. Citation Format: Nadine Reischmann, Lorenz Pudelko, Christopher Stroh, Nina Linde, Doreen Musch, Marina Keil, Linda Pudelko, Christina Esdar, Andree Blaukat, Karl M. Schumacher, Niki Karachaliou. MET or SHP2 inhibition enhances targeted therapies and delays the emergence of resistance in oncogene-driven NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1105.

Background: ALK and ROS1 fusion-positive NSCLC patients derive clinical benefit from tyrosine kinase inhibitors (TKIs) but ultimately relapse. Acquired resistance mechanisms include on-target secondary mutations or copy number gains and activation of bypass signaling. Although MET amplification has been described as a bypass resistance mechanism to ALK and ROS1 inhibitors, there are limited data on MET gene and protein overexpression. Aims: (i) detection of MET alterations at the DNA, mRNA and protein levels in ALK and ROS1 fusion-positive NSCLC patients progressing on TKIs, and (ii) establishment of primary cultures using samples from those patients. Methods: MET alterations were studied in 12 patients after progression on TKIs, 10 ALK and 2 ROS1 fusion-positive. Informed consent was obtained from all patients. NGS and FISH were used to detect resistance mutations and amplifications. MET mRNA expression levels were determined by nCounter. Total and phospho-MET levels were assessed by IHC and Western blotting. Results: A total of 21 samples were available from the 12 patients, including tumor biopsies (n=5), plasma (n=10), pleural effusions (n=3) and cerebrospinal fluids (n=3). MET alterations were detected in 4 patients, 3 ALK fusion-positive progressing on lorlatinib and one ROS1 fusion-positive patient progressing on crizotinib. The 3 ALK fusion-positive patients had MET amplification detected in liquid biopsy (n=2) or tumor tissue (n=1), collected after progression on lorlatinib. In the patient with tissue biopsy available, the increased MET copy number was in line with the presence of MET protein and RNA overexpression. MET amplification was not present on the pre-treatment biopsy available for one of the 3 patients. In primary cultures established from pleural effusion samples of 2 ALK fusion-positive patients, MET amplification was maintained, particularly if the cells were cultured in presence of an ALK TKI. Although the ROS1 fusion-positive patient had no MET amplification after progression on crizotinib, MET and phospho-MET upregulation were detected by IHC. These alterations were also present in primary culture that could be established from a pleural effusion sample of the patient. Conclusions: We found MET alterations in 4 out of 12 (33%) fusion-positive patients after progression on TKIs. Three of them had MET amplification and one MET protein overexpression in the absence of MET copy number gain. Despite the small size of the cohort, our results suggest that testing not only at the DNA but also at the RNA and protein levels, discovers amplification-negative patients with MET alterations who may derive benefit from a MET targeted therapy. Finally, our findings highlight the potential of pleural effusion as a source of material for the establishment of primary cultures. Citation Format: Núria Jordana-Ariza, Nadine Reischmann, Carlos Esparré, Ruth Román, Cristina Aguado-Esteban, Silvia García-Román, Christopher Stroh, Andrés Aguilar Aguilar, Rafael Rosell, Niki Karachaliou, Miguel A. Molina-Vila. Detection of MET alterations at the DNA, RNA and protein levels in NSCLC patients progressing on ALK and ROS1 targeted therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1106.

Background: Anti-EGFR monoclonal antibodies are treatment options for RAS and BRAF V600 mutation-negative CRC patients. However, the literature suggests that CRC patients with sub-clonal RAS and BRAF mutations may still benefit from anti-EGFR therapies. The Guardant INFORM™ real-world clinical-genomic database was utilized to assess the impact of sub-clonal RAS and BRAF alterations detected in circulating tumor DNA (ctDNA) by the Guardant360® test on the clinical outcome of CRC patients treated with anti-EGFR therapy. Methods: Patients were selected from the Guardant INFORM™ database using the following inclusion criteria: diagnosed with advanced CRC in the US; treated with anti-EGFR therapies starting within 90 days after a Guardant360 test result; and the presence of BRAF V600E and/or canonical KRAS/NRAS mutations (codons 12, 13, 59, 61, 117, 146). Time to next treatment (TTNT) and overall survival (OS) were compared for various RAS/BRAF mutation clonality cutoffs using the Cox proportional hazards model. Results: Of the 13,798 CRC patients in the Guardant INFORM database, 91% had detectable ctDNA, 913 received a Guardant360® test before anti-EGFR therapy, and 446 (48.8%) initiated anti-EGFR therapy within 90 days after the test. Among this cohort, 11% (n = 50) had a BRAF V600E mutation and 9% (n = 40) had a RAS mutation. The median RAS/BRAF clonality was 0.84 (IQR = 0.57, 1.00). The associated clinical outcomes for patients with sub-clonal and clonal RAS/BRAF mutations using clonality cutoffs from 0.3 to 0.8 are reported (Table). Conclusion: Using a liquid biopsy-based clinical-genomic dataset, we demonstrate that patients harboring sub-clonal RAS or BRAF mutations benefit from anti-EGFR therapy to a degree similar to wild-type patients. Given the limited patient numbers, this finding warrants additional investigation into the utility of ant-EGFR therapies as a treatment option for this subgroup of CRC patients. RAS/BRAF Mutation Clonality* Cutoff Sub-clonal** Clonal** HR (95% CI) P value HR (95% CI) P value TTNT 0.3 0.96 (0.42, 2.18) 0.913 1.72 (1.15, 2.59) 0.009 0.4 1.03 (0.48, 2.21) 0.946 1.72 (1.14, 2.60) 0.010 0.5 0.97 (0.45, 2.08) 0.931 1.77 (1.17, 2.66) 0.007 0.6 1.04 (0.51, 2.13) 0.922 1.76 (1.16, 2.66) 0.008 0.7 1.03 (0.55, 1.94) 0.919 1.90 (1.23, 2.93) 0.004 0.8 1.30 (0.75, 2.24) 0.350 1.72 (1.08, 2.74) 0.022 OS 0.3 1.72 (0.84, 3.54) 0.142 2.47 (1.61, 3.79) Citation Format: Khalid Abubaker, Danyi Wang, Zheng Feng, Christopher Stroh, Jiemin Liao, Gordon Otto, Juergen Scheuenpflug. Characterization of sub-clonal RAS/BRAF alterations in an anti-EGFR treated advanced CRC cohort using a liquid biopsy-based real world clinical genomics database [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5245.

9121 Background: Tepotinib, a potent, highly selective, oral, MET inhibitor, showed meaningful activity in patients (pts) with NSCLC with high-level METamp by LBx in VISION. Exploratory biomarker analyses are presented herein. Methods: Pts had 0–2 prior therapy lines, high-level METamp by LBx (Guardant360; MET copy number ≥2.5), and no MET exon 14 skipping or EGFR/ ALK alterations. Pts received tepotinib 500 mg once daily (450 mg active moiety). Primary endpoint was objective response by independent review; data cut-off: Aug 20, 2021. Exploratory biomarker analysis included LBx at baseline (BL), on treatment, and end of treatment (EOT). Early molecular response (eMR) was defined as undetectable METamp 6–8 weeks on treatment. Results: 24 pts were enrolled (median age: 63.4 years [yrs]; smokers: 88%; ECOG PS 1: 88%; adenocarcinoma: 67%). Treatment duration was ≥1 yr in five pts and ≥2 yrs in two pts (both ongoing). Overall, objective response rate (ORR) was 41.7% (95% CI: 22.1, 63.4). Treatment-naïve pts (n=7) had an ORR of 71.4% (29.0, 96.3), median (m) DOR was 14.3 months (2.8, not estimable [ne]), and mPFS was 15.6 months (1.4, ne). BL biomarker analyses according to clinical benefit (CR/PR/SD [n=11] vs PD/NE [n=13]) showed association with better outcomes in pts with focal METamp, or without MYCamp or RB1 mutation (Table). MYCamp/ RB1 mutation was detected in 4/7 pts with neuroendocrine/not otherwise specified histology; MYCamp in 2/3 pts with neuroendocrine histology. Low BL ctDNA mutant allele frequency (MAF) was associated with better outcomes. 14 pts had eMRs (ORR 71.4%); persistent METamp (n=4) was associated with lack of clinical response. 2/9 pts with EOT biomarker profiles had emerging resistance mechanisms (MET kinase domain mutations Y1230 and D1228); both had METamp re-emergence. Treatment-related adverse events included edema (composite term; any grade: 46%; Grade 3: 13%) and constipation (any grade: 17%; Grade ≥3: 0%). Conclusions: Tepotinib showed meaningful activity, especially in first line, in the first trial of a MET inhibitor in EGFR WT NSCLC with high-level METamp to enroll based on a convenient LBx assay. BL biomarker analyses indicated focal METamp, MYC/RB1 WT, and low ctDNA MAF were associated with improved outcomes. Serial LBx could monitor molecular response and evaluate resistance. Clinical trial information: NCT02864992. [Table: see text]

Summary 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., Graphical Abstract, Highlights • Tepotinib is a selective MET inhibitor with efficacy for METex14-positive NSCLC • Receptor tyrosine kinase signaling is activated in response to targeted therapies • SHP2 is a downstream effector of receptor tyrosine kinase signaling • SHP2 inhibition may enhance the antitumor activity of tepotinib, Treatment; Cancer

9012 Background: In the VISION study, tepotinib in METex14 skipping NSCLC pts (Cohort A) had robust and durable clinical activity. Serial LBx samples were collected for biomarker analyses, presented herein. Methods: LBx samples taken at baseline (BL), Week 6, 12, & end of treatment (EOT) were analyzed using Guardant360® CDx (73 genes). Investigator (INV)-assessed clinical outcome was evaluated per BL biomarker profiles and by molecular response (MR; defined as > 75% depletion from BL in METex14 variant allele frequency [VAF] ctDNA confirmed in 2 consecutive samples) or molecular progression (MP; defined as VAF increase > 0 from BL). Acquired resistance was investigated in EOT samples, following progression per INV. Results: LBx pts (n = 99) had a median age of 72 yrs (range 49–88), 53% were male, 44% never smokers, 85% had adenocarcinoma. INV ORR was 53% (95% CI 42, 63); ORR in 1L (n = 44) was 59% (43, 74) & ≥2L (n = 55) was 47% (33, 61). 94 pts had BL biomarker profiles; these were similar in 1L and ≥2L pts, except EGFR amp: 1/43 1L [2%] vs 8/51 ≥2L [16%]. Outcomes were not impacted by location/type of METex14 alteration. 1 pt with concomitant MET M1250T mutation had a PFS of 17.3 months. A trend towards better efficacy was seen in pts with concomitant MET amp (6 responses in 8 pts). Response to tepotinib occurred both in pts with wt or mutant TP53; however, there was a trend for longer mDOR in pts with wt TP53 (18.3 [95% CI 9.7, ne] vs 7.1 [4.7, 10.9] months) and mPFS (9.5 [6.7, 19.7] vs 5.1 [2.8, 6.9] months). Concomitant oncogenic mutations were rare, with no responses in 3 pts with KRAS, NRAS alterations and 3 responses in 5 pts with PI3K/AKT alterations. 65 pts had 2 consecutive on-treatment samples: 46 (71%) had confirmed MR, 5 (8%) had confirmed MP, 14 (22%) had no change in VAF or lacked confirmation. MR was associated with clinical response and MP was associated with no response/short PFS (Table). 52 pts with progression had EOT LBx samples. Emerging MET resistance mutations (Y1230H/C & D1228H/N) occurred in 7 (13%) pts, all responders and 5/7 had PFS > 10 months. Analyses on non-MET-driven resistance mechanisms will be presented. Conclusions: LBx biomarker analysis from the largest on-treatment data set for a MET inhibitor in METex14 skipping NSCLC, showed that ctDNA depletion in METex14 VAF is associated with improved clinical response in pts treated with tepotinib. This suggests serial LBx could help us to monitor response/non-response, understand resistance, and guide trials that test escalation/de-escalation strategies to improve outcomes and maximize QOL. Clinical trial information: NCT02864992. [Table: see text]

Amorphous ferromagnetic alloy with the composition Fe56Co24Nb4B13Si2Cu1 was obtained by rapid quenching from the melt. Samples cut from the ribbons were annealed at 450, 550, 650 and 750 °C in a vacuum furnace. 57Fe Mossbauer spectroscopy was used to identify the phases formed based on the refined values of the hyperfine parameters. The as-quenched specimen was analyzed with a hyperfine magnetic field distribution and corresponded to an in-plane orientation of the magnetic moment directions. The sample annealed at 450 °C was found to be in a nanocrystalline state due to observation of the (FeCo)-Si alloy with the DO3 structure. The balance of the composition was represented by a metalloid-enriched amorphous grain boundary phase. In contradistinction to this, the samples annealed at 550–750 °C were totally crystallized and the new phases formed were α-(FeCo), (FeCo)2(BSi) and (FeCo)3(BSi). These findings suggest that nanocrystallization is obtained only at select processing temperatures. A new set of Mossbauer spectra was obtained by recording simultaneously the intensity transmitted by a sandwich of the sample with the stainless steel etalon, based on the dual absorber method recently introduced by us. The values of the recoilless fraction can be derived from the relative spectral areas. The f factor value dropped from 0.6 to 0.37 for the sample annealed at 450 °C, consistent with the onset of nanocrystallization in the system. For the completely crystallized specimens, the f factor maintained values close to 0.5. This indicates that the presence of quenched-in stresses may play a role in the ability of samples to undergo recoilless emission and absorption of gamma rays.

329 Background: Tepotinib, a potent and highly selective MET inhibitor, showed promising activity in advanced HCC with MET overexpression in two Phase Ib/II trials, which both met their primary endpoints. One trial enrolled Asian patients (pts) without prior systemic therapy (first line [1L]; NCT01988493) and one enrolled US/European pts with prior sorafenib (second line [2L]; NCT02115373). By investigator assessment, objective response rates and disease control rates with tepotinib in Phase II were 15.8% and 60.5% in 1L (n = 38), and 8.2% and 57.1% in 2L (n = 49). Outcomes appeared better in pts with METamp. Thus, we further investigated the preclinical and clinical activity of tepotinib in HCC, focusing on high-level METamp, which could be an oncogenic driver in this tumor type. Methods: Preclinical activity was assessed in 37 HCC pt-derived xenografts (PDXs) in nude mice treated with tepotinib (100 mg/kg, Days 1–5, every 7 days for five cycles; 6–12 replicates per PDX). Clinical activity was assessed by analyzing pts with METamp or high-level METamp (defined as mean MET gene copy number [GCN] ≥5 and ≥10, respectively; by fluorescence in situ hybridization), who received tepotinib 500 mg in Phase Ib or II of the 1L and 2L trials (n = 121). In the Phase Ib part of the 1L trial, pts could have received prior treatment. Results: Molecular profiling revealed high-level METamp in two of 37 HCC PDXs: LIM612 ( MET GCN 47.1) and LIPF210 ( MET GCN 44). Tepotinib induced significant tumor regression in both of these high-level METamp HCC PDX models (mean tumor volume reduction: 97% and 96%, respectively). Across the two trials, 15 pts treated with tepotinib 500 mg had METamp, of whom five had an objective response (one complete response [CR] and four partial responses [PRs]) and six had stable disease (SD) as best overall response. Four pts had high-level METamp (mean MET GCN 14.3, 18.1, 30.2, and 36.2), with best overall response of CR in one pt, PR in two pts and SD in one pt (Table). One pt with high-level METamp (mean MET GCN 14.3) treated with 1L tepotinib was still receiving treatment as of Sept 2020 (total tepotinib treatment duration: > 45 months). Conclusions: High-level METamp may be an oncogenic driver in HCC that sensitizes tumors to MET inhibition with tepotinib. Compared with MET overexpression, high-level METamp could be a better predictive biomarker for MET inhibitors in this setting. Clinical trial information: NCT01988493, NCT02115373. [Table: see text]

x RuO 2 –(1− x )α-Fe 2 O 3 ( x =0.1, 0.3, 0.5 and 0.7) nanoparticle systems were successfully synthesized by mechanochemical activation of RuO 2 and α-Fe 2 O 3 mixtures for 0–12 h of ball milling. Mossbauer spectroscopy, X-ray diffraction (XRD), magnetic measurements, simultaneous differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were employed to investigate the phase evolution of x RuO 2 –(1− x )α-Fe 2 O 3 nanoparticle systems under the mechanochemical activation process. The Mossbauer studies showed that the spectrum of the mechanochemically activated composites evolved from a sextet for α-Fe 2 O 3 (hematite) to four sextets and a doublet upon duration of the milling process with ruthenium oxide. Rietveld refinement of the XRD patterns yielded the values of lattice parameters as function of composition and milling times. The presence of Ru-substituted hematite and Fe-doped ruthenium oxide was evidenced and correlated with differences between ionic radii of Fe 3+ and Ru 4+ . Magnetic measurements recorded at 5 and 300 K in applied magnetic fields of 50,000 and 100,000 Oe showed that the estimated saturation magnetization of the milled samples increased with ball milling time while preserving a multidomain magnetic structure. The Morin transformation was evidenced by zero-field cooling–field cooling (ZFC–FC) measurements in 200 Oe and 1 T, for samples milled for 0 and 8 h of mechanochemical activation. These results correlate well with the DSC–TGA measurements, which support the formation of mixed-oxide solid solutions in the system under investigation.

Purpose: In the ongoing, single-arm, Phase 2 VISION study (NCT02864992), tepotinib (a highly selective MET inhibitor) has shown durable clinical activity in NSCLC patients (pts) with METex14 skipping. Here, we report the biomarker profile of pts screened with liquid biopsy (LBx) for inclusion in the study. Methods: Pts with advanced NSCLC and previously confirmed EGFR/ALK wild-type status were prospectively screened for MET alterations using plasma samples collected during pre-screening/screening. Plasma ctDNA sequencing was performed at a central laboratory using a 73-gene next-generation sequencing panel (Guardant360®). Results: Of 6,034 pts screened, 813 pts had results pending at data cut and of 5,221 pts tested, sequencing failed in 41 pts. The success rate of LBx testing was consistent across centers. Of 5,180 patients analyzed, 694 pts (13.4%) had no mutation detected. Despite the intent of screening EGFR/ALK wild-type pts, 327 pts (6.3%) had EGFR mutations and 49 (0.9%) had ALK/ROS fusions. 188 pts (3.6%) had METex14 skipping (Table) and 256 pts (4.9%) had MET amplification (amp) without METex14 skipping. The median age of METex14 pts was 72 years; 47% were male; 46% were never smokers and 65% had adenocarcinoma histology. In METex14 pts, the most frequently occurring driver co-alterations were amp in MET (13.3%), EGFR (7.4%), CDK4 (6.4%), BRAF (5.3%) and CDK6 (4.8%), and mutations in GNAS (5.3%). In METamp pts, the most frequently occurring driver co-alterations were CDK6 (60.5%), BRAF (43.4%), EGFR (28.9%), MYC (21.9%) and CCNE1 (19.9%) amps. Overall, TP53 mutations were detected in 55.9% of METex14 pts and 79.7% of METamp pts. Table:Characterization of METex14 skipping (n=188)n (%)Insertions/deletions (indels)93 (49.5)Indel at acceptor site54 (28.7)Indel at donor site36 (19.1)Whole exon 14 deletion3 (1.6)Single nucleotide variation (SNV)95 (50.5)SNV at donor site93 (49.5)SNV at acceptor site2 (1.1)SNVs and indelsSNV/indel at donor site129 (68.6)SNV/indel at acceptor site56 (29.8)SNV/indel whole exon 14 deletion3 (1.6) Conclusions: In this population, METex14 skipping can be successfully detected through non-invasive LBx analysis using a next-generation sequencing panel. The rate of METex14 skipping and the genomic profile and demographics of pts were similar to previously reported data. Citation Format: Xiuning Le, Dariusz Kowalski, Byoung Chul Cho, Pierfranco Conte, Enriqueta Felip, Marina Chiara Garassino, Santiago Viteri, Gee-Chen Chang, John Richart, Luiz Paz-Ares, Dilafruz Juraeva, Josef Straub, Christopher Stroh, Paul Paik. Liquid biopsy to detect MET exon 14 skipping (METex14) and MET amplification in patients with advanced NSCLC: Biomarker analysis from VISION study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3385.

Background Patients with advanced non-small cell lung cancer (NSCLC) harboring oncogenic MET alterations, such as MET exon 14 skipping or MET amplification (MET amp), benefit from MET tyrosine kinase inhibitor (TKI) treatment. Brain metastases are common in patients with advanced NSCLC. In preclinical studies in rats, tepotinib had relatively high binding to brain tissue (fu br=0.4%, fu pl=4%) and free tepotinib concentrations in brain were 25% of the concentrations found in plasma (Kp u,u=0.25). In this study we investigated the efficacy of the MET TKIs tepotinib, capmatinib, savolitinib and crizotinib in mice implanted orthotopically with MET-dependent tumor explants derived from human NSCLC brain metastases. Methods The antitumor activity of tepotinib (30 mg/kg qd) was investigated in a screen of 21 subcutaneous lung cancer patient-derived xenograft (PDX) models of brain metastases grown in NOD-SCID mice (n=1/model). 20 of these tumors were retrospectively analyzed for cancer-specific mutations, gene copy number (GCN) and gene expression by Nanostring. 2 responding models, both found to harbor MET amp, were tested again subcutaneously in NOD-SCID mice treated with vehicle or tepotinib (125 mg/kg qd; n=5). Both models were orthotopically implanted into brains of NOD-SCID mice and tumor growth was monitored by MRI. Established tumors were treated with MET TKIs (n=10) tepotinib (125 mg/kg qd), capmatinib (30 mg/kg bid), savolitinib (60 mg/kg qd) or crizotinib (50 mg/kg qd). Results 2 of 21 subcutaneous PDX tumors (LU5406 and LU5349) regressed in response to tepotinib treatment. When implanted subcutaneously again into mice, both models regressed completely upon treatment with tepotinib. Molecular profiles revealed that these were the only tumors of the 20 models investigated by Nanostring that had MET amp (high-level increase in MET GCN of >10). Both models grew orthotopically when implanted into brains of mice. Contrast-weighted MRI indicated regions with intact and disrupted blood–brain barrier (BBB) in all implanted tumors. Tumor regression of orthotopic LU5406 tumors was observed with all MET TKIs (% median tumor volume changes [%TV]: tepotinib, –63%; capmatinib, –24%; savolitinib, –38%; crizotinib, –27%). In the orthotopic LU5349 tumors, treatment with crizotinib or savolitinib led to growth inhibition (%TV: +88% and –13%, respectively), whereas tepotinib and capmatinib induced tumor regression (%TV: –84% and –63%, respectively). Conclusions The heterogenous pattern of regions with intact and disrupted BBB in the orthotopic brain metastases models is thought to mirror the clinical situation. Tepotinib was efficacious in the two MET-driven orthotopic brain metastases PDX tumors characterized by pronounced tumor regression and may be relevant to patients with brain metastases. Relationships between efficacy and BBB leakiness will be discussed. Citation Format: Manja Friese-Hamim, Anderson Clark, Lindsey Crowley, Christof Reusch, Olga Bogatyrova, Claudia Wilm, Hong Zhang, Timothy Crandall, Jing Lin, Jianguo Ma, David Bachner, Jürgen Schmidt, Martin Schaefer, Christopher Stroh. Anti-tumor activity of tepotinib in orthotopic models of lung cancer patient-derived brain metastases with MET amplification [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3407.

Inhibidor de MET; NSCLC Inhibidor de MET; NSCLC MET inhibitor; NSCLC 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. This work was supported by Merck KGaA, Darmstadt, Germany . No grant number is applicable.

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.

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.

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.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.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], p0·0001). 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).The efficacy of chemotherapy plus cetuximab in the first-line treatment of advanced NSCLC seems to be independent of each of the biomarkers assessed.Merck KGaA.

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.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.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, P0.001), infusion-related reactions (in 2.5% vs. 0%, P0.001), and diarrhea (in 15.7% vs. 10.5%, P=0.008).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.)

Purpose This randomized study assessed whether the best overall response rate (ORR) of cetuximab combined with oxaliplatin, leucovorin, and fluorouracil (FOLFOX-4) was superior to that of FOLFOX-4 alone as first-line treatment for metastatic colorectal cancer. The influence of KRAS mutation status was investigated. Patients and Methods Patients received cetuximab (400 mg/m2 initial dose followed by 250 mg/m2/wk thereafter) plus FOLFOX-4 (oxaliplatin 85 mg/m2 on day 1, plus leucovorin 200 mg/m2 and fluorouracil as a 400 mg/m2 bolus followed by a 600 mg/m2 infusion during 22 hours on days 1 and 2; n = 169) or FOLFOX-4 alone (n = 168). Treatment was continued until disease progression or unacceptable toxicity. KRAS mutation status was assessed in the subset of patients with assessable tumor samples (n = 233). Results The confirmed ORR for cetuximab plus FOLFOX-4 was higher than with FOLFOX-4 alone (46% v 36%). A statistically significant increase in the odds for a response with the addition of cetuximab to FOLFOX-4 could not be established (odds ratio = 1.52; P = .064). In patients with KRAS wild-type tumors, the addition of cetuximab to FOLFOX-4 was associated with a clinically significant increased chance of response (ORR = 61% v 37%; odds ratio = 2.54; P = .011) and a lower risk of disease progression (hazard ratio = 0.57; P = .0163) compared with FOLFOX-4 alone. Cetuximab plus FOLFOX-4 was generally well tolerated. Conclusion KRAS mutational status was shown to be a highly predictive selection criterion in relation to the treatment decision regarding the addition of cetuximab to FOLFOX-4 for previously untreated patients with metastatic colorectal cancer.

Although caspase-8 has an established role as an initiator of death receptor-mediated apoptosis, the function of its closest homolog, caspase-10, is almost completely unknown. To gain a closer insight into the physiological function of caspase-10, we compared the cleavage of known caspase-8 substrates by both initiator caspases. We demonstrate that caspase-10 and -8 have overlapping cleavage preferences for several substrates such as the kinases RIP and PAK2. Interestingly, in other substrates, such as the Bcl-2 protein Bid, we found additional and distinct cleavage sites for both caspases, which might have important consequences for mitochondrial targeting and propagation of the death signal. Caspase-8 and -10 also caused different interchain cleavage patterns of their enzyme precursors. Together, these results suggest that caspase-8 and -10, despite having overlapping functions, also have selective substrate cleavage specificities and might thereby exert nonredundant roles in apoptosis signaling.

In many cancers, a high constitutive activation of transcription factor NF-kappaB has been implicated in tumor progression and apoptosis resistance, making NF-kappaB an attractive target for cancer therapy. Here, we describe the specific inhibition of NF-kappaB by the intracellular delivery of IkappaBalpha through VP22-mediated protein transduction. The Herpes virus protein VP22 has attracted great attention in gene therapy, because of its ability to migrate from an original expressing cell into surrounding recipient cells, resulting in high levels of protein transduction. To evaluate the use of VP22 as a vehicle for NF-kappaB inhibition, we expressed several versions of VP22-IkappaBalpha fusion proteins in baculovirus, bacteria, and mammalian cells. While we could not detect transcellular migration of different VP22-IkappaBalpha constructs, interestingly, baculovirally expressed VP22-IkappaBalpha was efficiently delivered into cells after exogenous administration. The purified and imported VP22-IkappaBalpha retained its function and efficiently inhibited both constitutive and inducible NF-kappaB activation. We further show that the 34 C-terminal amino acids of VP22 were sufficient for the import property, suggesting also that the ability of intercellular migration and cellular import are not linked to each other. Together, our results demonstrate that recombinant VP22 acts as an efficient vehicle for the exogenous delivery of IkappaBalpha and, moreover, might find applications to block NF-kappaB activation specifically.

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. Clin Cancer Res; 20(17); 4478–87. ©2014 AACR.

At present, mammalian caspases comprise a group of at least 13 protease members which either generate mature pro-inflammatory cytokines or promote apoptosis (Cohen, 1997; Nicholson and Thornberry, 1997; Van de Craen et al, 1997; Humke et al, 1998; Schulze-Osthoff et al, 1998). Based on phylogenetic analysis and positional scanning studies of their peptide substrates, caspases can be divided into three subfamilies: The ICE-like protease family includes caspase-1, -4, -5 and -13 as well as murine caspase-11 and -12, for which no human equivalents have yet been identified. The Ced-3 subfamily includes caspase-3, -6, -7, -8, -9 and -10, whereas the third subfamily consists of only one member, caspase-2. Within each subfamily, the peptide sequence preferences in the substrates are remarkably similar or even identical. This demonstrates that, at least in some cases, different caspases can cleave the same substrates, suggesting some degree of functional redundancy within the caspase family. Central to the understanding of the molecular mechanism of cell death is the identification of caspase targets and the elucidation of the consequences of proteolytic cleavage. Thus far, more than 60 proteins have been found to be cleaved by caspases, and new substrates are continuously being identified (Table 1). Given the great number of different caspases, the list of substrates is still relatively small. For most proteins, the consequences of cleavage are poorly understood. In a few cases, however, proteolysis of certain components can be linked to discrete morphological changes of cell death. Which requirements should an apoptosis-relevant caspase substrate meet? Because apoptosis is an ordered sequence of rather stereotypical alterations in every cell type, one would predict that caspase substrates should be ubiquitously expressed and evolutionary conserved, at least in their aspartate cleavage site. The known substrates of caspases can be loosely categorized into a few functional groups including proteins involved in scaffolding of the cytoplasm and cell nucleus, signal transduction and transcription-regulatory proteins, cell-cycle controlling components and proteins involved in DNA replication and repair. In addition, activation of members of the first subfamily of caspases, caspase-1 and presumably caspase-4 and -5, results in the processing of cytokine precursors, which are presumably not directly involved in cell death. While some substrates are functionally inactivated upon caspase-mediated cleavage, other proteins and enzymes can be activated, mostly by cleavage of an inhibitory or regulatory domain within the caspase target. In most cases the physiological consequence of this gain-of-function cleavage for apoptosis remains unclear. Caspasemediated cleavage should result in different net effects: (i) a halt of cell cycle progression, (ii) disabling of repair mechanisms, (iii) disassembly of molecular structures, (iv) cell detachment, and (v) tagging of the apoptotic cell for engulfment by phagocytes. A number of structural proteins in the cell nucleus and cytoplasm have been identified to be cleaved by caspases, such as actin, fodrin, catenins, keratins, Gas2 and lamins (for references see Cohen, 1997; Nicholson and Thornberry, 1997; Porter et al, 1997; Tan and Wang, 1998; Cryns and Yuan, 1998). Degradation of lamin B which is predominantly mediated by caspase-6 may lead to the disassembly of the nuclear envelope and the final collapse of the cell nucleus (Rao et al, 1996). In contrast, cleavage of gelsolin, a cytoplasmic actin-severing protein, may contribute to membrane blebbing and other morphological features of the apoptotic phenotype. Gelsolin is cleaved by caspase-3 to generate a constitutively active fragment that can depolymerize F-actin (Kothakota et al, 1997). Interestingly, gelsolin-deficient cells show a strong delay in membrane blebbing when exposed to apoptotic stimuli. It has been also reported that actin can be directly cleaved by caspases in pheochromocytoma and ovarian carcinoma cells (Kayalar et al, 1996; Chen et al, 1996), whereas in many other cell types no cleavage could be detected (Song et al, 1997). Thus, it is possible that certain protein cleavages may be cell typespecific which may also due to variations in the expression of individual caspases in different cell types. Activation of caspases may be not only required for destruction of the cell's architecture, but also necessary for the detachment and clearance of an apoptotic cell from the embedding tissue. Indeed, some caspase substrates participate in cell adhesion, such as b-catenin, plakoglobin and focal adhesion kinase (Brancolini et al, 1997; 1998; Herren et al, 1998; Crouch et al, 1996; Levkau et al, 1998a). A strikingly large number of caspase targets are involved in cell cycle regulation and DNA repair mechanisms. One of the first death substrates found to be cleaved by caspases was poly(ADP-ribose)polymerase (PARP), which catalyzes the transfer of ADP-ribose polymers to nuclear proteins (Tewari et al, 1995). As DNA strand breaks activate the enzyme, PARP has been proposed to trigger DNA damageinduced apoptosis by depleting NAD stores. On the other hand, due to its role in DNA repair, cleavage of PARP may Cell Death and Differentiation (1998) 5, 997 ± 1000 a 1998 Stockton Press All rights reserved 13509047/98 $12.00

The anti-EGFR monoclonal antibodies (MoAbs) cetuximab and panitumumab are used to treat ‘RAS’ wild type metastatic colorectal cancer (MCRC), providing significant clinical benefit in patients. However, all patients ultimately develop disease progression, driven by acquisition of mutations in downstream effectors and in the extracellular domain (ECD) of EGFR, in approximately 25% of the cases. Sym004 is a novel 1:1 mixture of two non-overlapping anti-EGFR MoAbs that has recently shown 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. 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 an EGFR mutation in the post-cetuximab tumor sample. Sym004 effectively bound and abrogated ligand-induced phosphorylation of all individual EGFR mutants. Cells resistant to cetuximab harboring EGFR ECD mutations 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 a proof of principle, a patient with a tumor harboring an EGFR mutation (G465R) following cetuximab therapy benefited from Sym004 therapy. These data suggest that Sym004 is an active drug in MCRC resistant to cetuximab/panitumumab mediated by EGFR mutations. Overall, EGFR mutations are potential biomarkers of response to Sym004 to be evaluated in ongoing large clinical trials. Citation Format: Francisco J. Sanchez-Martin, Alba Dalmases, Beatriz Bellosillo, Guillem Argiles, Mariona Gelabert, Israel Cañadas, Joana Vidal, Giulia Siravegna, Sabrina Arena, Klaus Koefoed, Laura Visa, Oriol Arpí, Ivan D. Horak, Mar Iglesias, Christopher Stroh, Michael Kragh, Ana Rovira, Joan Albanell, Alberto Bardelli, Josep Tabernero, Clara Montagut. The anti-EGFR antibody mixture Sym004 overcomes acquired resistance to cetuximab in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2149.

Cryopreserved cells and tissues are increasingly used for stem cell transplantation and tissue engineering. However, their freezing, storage, and thawing is associated with severe damage, suggesting the need for better cryopreservation methods. Here, we show that activation of caspase-3 is induced during the freeze-thaw process. Moreover, we demonstrate that prevention of caspase activation by the caspase inhibitor zVAD-fmk strongly improves the recovery and survival of several cryopreserved cell types and hematopoietic progenitor cells. A short preincubation with the caspase inhibitor after thawing also enhances the colony-forming activity of hematopoietic progenitor cells up to threefold. Furthermore, overexpression of Bcl-2, but not the blockade of the death receptor signaling, confers protection, indicating that cryoinjury-associated cell death is mediated by a Bcl-2-controlled mitochondrial pathway. Thus, our data suggest the use of zVAD-fmk as an efficient cryoprotective agent. The addition of caspase inhibitors may be an important tool for the cryopreservation of living cells and advantageous in cell transplantation, tissue engineering, and other genetic technologies.

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/m2 initial dose then 250 mg/m2 per week; patients in the dose-escalation arms received 400 to 700 mg/m2 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 p27Kip1 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.

Tyrosine kinases of the Src family have been implicated in key biological processes. Here, we provide evidence that p56(Lck), a lymphoid-specific Src kinase, is involved in the activation of the mitochondrial apoptosis pathway. Lck-deficient T cells were completely resistant to anticancer drugs. In contrast, apoptosis sensitivity to death receptors was not altered, indicating a specific interference of Lck with the mitochondrial pathway. Re-expression of Lck restored sensitivity to drug-induced apoptosis and triggered mitochondrial cytochrome c release and caspase activation. Further analysis identified that the sensitization by Lck was independent of classical mediators of T-cell signaling, but essentially involved the Bcl-2 protein Bak. Expression of Bak was completely absent in Lck-deficient cells, while re-expression of Lck transcriptionally triggered Bak expression and conferred sensitivity to apoptosis, associated with a proapoptotic conformational change of Bak. Furthermore, in vitro the truncated fragment of Bid specifically activated Bak and cytochrome c release only from mitochondria of Lck-expressing cells. These results do not only demonstrate a sentinel role of Lck in drug resistance but also delineate a hitherto unknown pathway of Src kinases in regulation of Bcl-2 proteins.

Proteinase-activated receptor-2 (PAR2) belongs to a new G protein-coupled receptor subfamily that is activated by various serine proteases. Recent knowledge indicates that PAR2 is involved in cutaneous inflammation and immune response. PAR2 is highly expressed by human keratinocytes (KTC). The underlying mechanisms of PAR2-mediated KTC function and cutaneous immune response are, however, still incomplete. Therefore, we investigated the activation of important signaling cascades in primary human KTC after PAR2-stimulation using specific agonists. Moreover, we compared PAR2-immunoreactivity in the epidermis of inflammatory dermatoses and normal human skin. Electrophoretic mobility shift assays and morphological transduction studies revealed PAR2-induced activation and translocation of nuclear factor kappa B (NF-kappaB) in primary human KTC with a maximum after 1 h. Supershift analysis demonstrated acivation of the p50/p65 heterodimer complex. PAR2 agonists also induced upregulation of intercellular adhesion molecule-1 (ICAM-1) RNA, as shown by RT-PCR. Use of NF-kappaB inhibitors prevented upregulation of the cell adhesion molecule ICAM-1 in KTC indicating a direct role of NF-kappaB in PAR2-mediated upregulation of ICAM-1. Fluorescence-activated cell sorter analysis confirmed PAR2-induced and NF-kappaB-mediated upregulation of ICAM-1 protein after 13 h. Moreover, increased expression of PAR2 was detected in KTC of patients with atopic dermatitis suggesting a role of PAR2 in human skin inflammation. In conclusion, PAR2 induces upregulation of cell adhesion molecules such as ICAM-1 in primary human KTC via NF-kappaB activation, and is upregulated in KTC during cutaneous inflammation. Thus, PAR2 may play an important regulatory role of human KTC during inflammation and immune response.

Apoptosis or programmed cell death is a set of ordered events that enables the selective removal of cells from tissue and is essential for homeostasis and proper function of multicellular organisms. Components of this signaling network, which include ligands, such as CD95, tumor necrosis factor (TNF) and TNF-related apoptosis-inducing ligand, as well as downstream molecules, such as caspases, Bcl-2 family members, and inhibitor-of-apoptosis proteins, which trigger and regulate apoptosis, are crucial targets for conventional drug development and gene therapy of cancer and other diseases. Here, we focus on apoptotic pathways and propose new potential molecular targets that could prove effective in controlling cell death in the clinical setting.