Epidermal Growth Factor Receptor mAb Research Articles

Abstract LB056: IBI334, a novel ADCC-enhanced B7-H3/EGFR bispecific antibody, demonstrated potent pre-clinical efficacy in solid tumors

Abstract Many solid tumors, such as colorectal cancer (CRC) and lung cancer, are dependent on epidermal growth factor receptor (EGFR) pathway for tumor growth. Antibodies that inhibit EGFR signaling, such as Cetuximab, show clinical efficacy but are associated with on-target toxicities that potentially limit the drug efficacy. To enhance the EGFR signaling inhibition and reduce on-target toxicities, we performed bioinformatics analysis for EGFR/TAA co-expression. We found that B7-H3, a member of the B7 family of immune checkpoint proteins, is broadly expressed in many solid tumors and their expression correlates with EGFR expression in multiple cancers, including lung cancer, head and neck cancer, pancreatic cancer and esophageal cancer. Using Innovent’s proprietary Innobody platform, we developed a bispecific antibody, IBI334, against B7-H3 and EGFR. IBI334 has an EGFR arm for signal blockage and is coupled with a fine-tuned B7-H3 arm with optimal affinity and binding domain. With the aid of B7-H3, IBI334 showed enhanced EGFR signal inhibition than Zalutumumab (EGFR mAb) and Amivantamab (c-met/EGFR bsAb). In addition, IBI334 is afucosylated to enhance its antibody-mediated cell cytotoxicity (ADCC) effects as compared to wild type antibody. IBI334 showed significantly better in vivo efficacy than Amivantamab in NCI-H358 (bronchioalveolar carcinoma with KRAS-G12C mutation), NCI-H292 (lymph node metastasis of a pulmonary mucoepidermoid carcinoma), SK-MES1 (lung cancer) and SK-MES1-LTC (lung cancer with EGFR L858R, T790M and C797S mutations) xenograft models and comparable efficacy in NCI-H322-EGFRexon20ins (lung cancer) model. Cetuximab, an EGFR monoclonal antibody, had high on-target toxicity with 50% early mortalities in cynomolgus monkeys at 120/75 mg/kg/week. With the careful design of B7-H3/EGFR bispecific antibody, IBI334 ameliorated the on-target toxicities and showed only slight hardening of the skin at the injection site at 120 mg/kg/week. As a result, IBI334 has a large therapeutic window of >200 folds. In conclusion, IBI334 is a potent B7-H3/EGFR bispecific antibody with broad application in many EGFR-driven solid tumors. The large therapeutic window enables safe and effective cancer treatment at high exposure levels. Citation Format: Jian Guan, Shuaixiang Zhou, Weiwei Wu, Tianyu Zhu, Lei Cao, Ming Wu, Ninghuan Li, Fenggen Fu, Zhengguan Liao, Shuming Lin, Zeyu Liu, Mengjia Zhu, Nana Luo, Ying Zhang, Tiong Sun Chia, Bingliang Chen, Kaijie He. IBI334, a novel ADCC-enhanced B7-H3/EGFR bispecific antibody, demonstrated potent pre-clinical efficacy in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB056.

Interactions of epitopic variants of epidermal growth factor receptor with therapeutic anti- EGFR antibodies

Epidermal growth factor receptor (EGFR) plays important roles in cancerous transformation of epithelial cells in many solid cancers. Due to the pivotal role of EGFR in cellular proliferation and metastasis, it is a promising molecular target for the treatment of various cancers. One of the major treatment approaches uses anti-EGFR monoclonal antibodies (mAbs) targeted to the extracellular domain of the receptor to competitively block the binding of its ligands. Cetuximab, necitumumab, nimotuzumab, and panitumumab are such approved mAbs which are commercially available and used to treat multiple types of cancers. The response rates to these expensive therapeutics in various cancers range from nearly 9% to 91%. Hence, the objective of this study was to indentify whether any of the missense single nucleotide polymorphisms (SNPs) in the EGFR gene impart any structural and functional impact on the receptor’s interaction with these antibodies. We used X-ray crystallographic structures (from Protein Data Bank) of the Fab fragments of these therapeutic antibodies in complex with EGFR to analyze the effects of the missense mutations on the antigen-antibody interactions. We also assessed the potential association of the destabilizing variants with pathogenicity and disease susceptibility. EGFR H433Q (rs1171743336), S464T (rs746763556), S492G (rs1057519760) and S492R (rs1057519860) variants appear to weaken interactions between EGFR and cetuximab, which is the most widely used anti-EGFR therapeutic antibody. Other epitopic variants do not appear to affect interactions between EGFR and relevant mAbs (necitumumab, nimotuzumab, and panitumumab). Prior to treatment of the EGFR mediated conditions with cetuximab, screening of variants that destabilize antibody-EGFR interaction may be considered as a companion diagnostic test for avoiding unresponsiveness and improving therapeutic outcomes. Dhaka Univ. J. Biol. Sci. 30(3 CSI): 393-403, 2022 (June)

The effects of somatic mutations on EGFR interaction with anti-EGFR monoclonal antibodies: Implication for acquired resistance.

A number of mutations in the epidermal growth factor receptor (EGFR) have been identified that imparts resistance to anti-EGFR monoclonal antibodies (mAbs) in clinical and preclinical samples. Primary or acquired resistance to targeted therapy will eventually limit the clinical benefit of anticancer mAbs. The aim of the current study was to perform computational analysis to investigate the structural implications of the EGFR somatic mutations on its complexes with the four anti-EGFR mAbs (Cetuximab, Panitumumab, Necitumumab, and Matuzumab). Docking analysis and molecular dynamics (MD) simulations were performed to understand the plausible structural and dynamical implications caused by somatic mutations available in the Catalogue of Somatic Mutations in Cancer database on the EGFR and anti-EGFR mAbs. We found that EGFRS492R and EGFRV441I in complex with Cetuximab, EGFRR377S and EGFRS447Y in complex with Panitumumab, and EGFRV441I in complex with Necitumumab have a weakest binding affinity in comparison to EGFRWT in complex with the relevant mAb. Taken together with the results obtained from docking analysis and MD simulations, the present findings may suggest that, the S492R and V441I mutations confer resistance to Cetuximab, R377S and S447Y mutations mediate resistance to Panitumumab and finally, V441I mutation also confers resistance to Necitumumab.

CB-839, panitumumab, and irinotecan in RAS wildtype (WT) metastatic colorectal cancer (mCRC): Phase I results.

574 Background: Epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) are approved in RAS WT mCRC; however, patients (pts) will develop resistance to these agents. Alterations in glutamine (Gln) metabolism play a critical role in cancer cell growth. In cancers such as CRC, EGFR and Gln cooperate to provide signals and fuel for mitogen activated protein kinase-dependent cell growth. Our in vitro data show that Gln abrogates EGFR inhibition, and blockade of Gln transport restores sensitivity. We also observed a greater antitumor response in vivo with EGFR mAb plus CB-839, an inhibitor of a rate-limiting enzyme of Gln metabolism, than either agent alone. We designed a phase I/II study (NCT03263429) to evaluate CB-839 + panitumumab + irinotecan in anti-EGFR refractory RAS WT mCRC. Methods: Dose escalation used a Bayesian continual reassessment method targeting a 25% toxicity probability. CB-839 (600 mg or 800 mg twice daily [BID]) were evaluated with panitumumab (6 mg/kg) and irinotecan (180 mg/m2). Irinotecan was included in phase I to establish a future phase II dose of the triplet. Prior EGFR mAb treatment (tx) was not required for phase I. Dose-limiting toxicity (DLT) was any tx-related non-hematologic ≥Gr 3 toxicity (except fatigue, rash, or elevated liver enzymes) or ≥Gr 4 hematologic toxicity during the first 28 days. Results: Nine pts have been enrolled; 2 were not evaluable for DLT and replaced. Zero DLTs were observed at dose level 1 (n = 3) or 2 (n = 4); 2 more pts are needed to confirm the maximum tolerated dose (MTD). Most frequent toxicities were anemia and hypomagnesemia (88%) and elevated alkaline phosphatase, nausea, and rash (75%), most ≤Gr 2. One of 7 evaluable pts (14%) has an ongoing partial response, and 5 pts had stable disease (SD; 71%). Three pts have been on tx > 6 months, and 3 pts with prior EGFR mAb tx achieved SD. Conclusions: Triplet combination was tolerable at full doses of each drug, and preliminary antitumor activity was observed in a majority of pts. Phase II will begin after phase I completion and will evaluate efficacy of CB-839 (800 mg BID) and panitumumab (6 mg/kg). Imaging studies using investigational PET tracers to evaluate Gln metabolism as a function of tumor response are planned. Clinical trial information: NCT03263429.

Characterization of 7A7, an anti-mouse EGFR monoclonal antibody proposed to be the mouse equivalent of cetuximab.

The Epidermal Growth Factor Receptor (EGFR) is selectively expressed on the surface of numerous tumours, such as non-small cell lung, ovarian, colorectal and head and neck carcinomas. EGFR has therefore become a target for cancer therapy. Cetuximab is a chimeric human/mouse monoclonal antibody (mAb) that binds to EGFR, where it both inhibits signaling and induces cell death by antibody-dependent cell mediated cytotoxicity (ADCC). Cetuximab has been approved for clinical use in patients with head and neck squamous cell carcinoma (HNSCC) and colorectal cancer. However, only 15-20% patients benefit from this drug, thus new strategies to improve cetuximab efficiency are required. We aimed to develop a reliable and easy preclinical mouse model to evaluate the efficacy of EGFR-targeted antibodies and examine the immune mechanisms involved in tumour regression. We selected an anti-mouse EGFR mAb, 7A7, which has been reported to be “mouse cetuximab” and to exhibit similar properties to its human counterpart. Unfortunately, we were unable to reproduce previous results obtained with the 7A7 mAb. In our hands, 7A7 failed to recognize mouse EGFR, both in native and reducing conditions. Moreover, in vivo administration of 7A7 in an EGFR-expressing HPV38 tumour model did not have any impact on tumour regression or animal survival. We conclude that 7A7 does not recognize mouse EGFR and therefore cannot be used as the mouse equivalent of cetuximab use in humans. As a number of groups have spent effort and resources with similar issues we feel that publication is a responsible approach.

Efficacy and safety of anti-EGFR agents administered concurrently with standard therapies for patients with head and neck squamous cell carcinoma: a systematic review and meta-analysis of randomized controlled trials.

Agents targeting epidermal growth factor receptor (EGFR) are used to treat head and neck squamous cell carcinoma (HNSCC); however, their efficacy and safety is poorly understood. Here we evaluated the efficacy and safety of anti-EGFR agents administered concurrently with standard therapies for HNSCC. Randomized controlled trials that evaluated addition of EGFR targeted therapy versus standard therapy alone were included. The primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS), overall response rate (ORR), locoregional control, and severe adverse events (SAEs, grade ≥ 3). Sixteen eligible trials with 4031 patients were included. Addition of anti-EGFR regimens to standard therapy significantly improved OS of patients with HNSCC (HR = 0.89; 95% CI, 0.82-0.96), with a moderately elevated rate of SAEs (RR = 1.08; 95% CI, 1.03-1.13). Subgroup analysis indicated that the survival benefit was observed when cetuximab was administered concurrently with radiotherapy (RT) for stage III/IV patients (HR = 0.76; 95% CI, 0.61-0.94; p = 0.01), or with chemotherapy for recurrent or metastatic (R/M) HNSCC (HR = 0.86; 95% CI, 0.78-0.95; p = 0.005). Significantly increased ORR (RR = 1.51; 95% CI 1.05-2.18) and PFS (HR = 0.72; 95% CI, 0.59-0.88) were found in R/M HNSCC patients treated with anti-EGFR plus chemotherapy, while no significant improvements were found in stage III/IV patients treated with anti-EGFR plus standard therapy. In conclusion, addition of cetuximab to standard therapy may improve outcomes for R/M HNSCC patients, while causing a moderate increase in SAEs. For stage III/IV patients, anti-EGFR mAb plus RT can improve OS compared with RT alone, while replacement of chemotherapy with EGFR mAb or adding EGFR mAb to combined chemotherapy and RT did not improve outcomes.

Epidermal growth factor receptor (EGFR) inhibitors for metastatic colorectal cancer.

Epidermal growth factor receptor (EGFR) inhibitors for metastatic colorectal cancer.

Nimotuzumab Induces NK Cell Activation, Cytotoxicity, Dendritic Cell Maturation and Expansion of EGFR-Specific T Cells in Head and Neck Cancer Patients.

Survival benefit and long-term duration of clinical response have been seen using the epidermal growth factor receptor (EGFR)-targeted monoclonal antibody (mAb) nimotuzumab. Blocking EGFR signaling may not be the only mechanism of action underlying its efficacy. As an IgG1 isotype mAb, nimotuzumab’s capacity of killing tumor cells by antibody dependent cellular cytotoxicity (ADCC) and to induce an immune response in cancer patients have not been studied. ADCC-induced by nimotuzumab was determined using a 51Cr release assay. The in vitro effect of nimotuzumab on natural killer (NK) cell activation and dendritic cell (DC) maturation and the in vivo frequency of circulating regulatory T cells (Tregs) and NK cells were assessed by flow cytometry. Cytokine levels in supernatants were determined by ELISA. ELISpot was carried out to quantify EGFR-specific T cells in nimotuzumab-treated head and neck cancer (HNSCC) patients. Nimotuzumab was able to kill EGFR+ tumor cells by NK cell-mediated ADCC. Nimotuzumab-activated NK cells promoted DC maturation and EGFR-specific CD8+ T cell priming. Interestingly, nimotuzumab led to upregulation of some immune checkpoint molecules on NK cells (TIM-3) and DC (PD-L1), to a lower extent than another EGFR mAb, cetuximab. Furthermore, circulating EGFR-specific T cells were identified in nimotuzumab-treated HNSCC patients. Notably, nimotuzumab combined with cisplatin-based chemotherapy and radiation increased the frequency of peripheral CD4+CD39+FOXP3+Tregs which otherwise were decreased to baseline values when nimotuzumab was used as monotherapy. The frequency of circulating NK cells remained constant during treatment. Nimotuzumab-induced, NK cell-mediated DC priming led to induction of anti-EGFR specific T cells in HNSCC patients. The association between EGFR-specific T cells and patient clinical benefit with nimotuzumab treatment should be investigated.

Patient considerations in metastatic colorectal cancer - role of panitumumab.

Epidermal growth factor receptor (EGFR) is overexpressed in many malignancies, including colorectal cancer (CRC), making EGFR an attractive treatment option. Panitumumab and cetuximab, monoclonal antibodies (mAbs) directed at EGFR, are both currently utilized in the management of metastatic CRC (mCRC). Through the development of these agents in mCRC, key issues surrounding each mAbs use have been revealed. These key issues include negative patient outcome avoidance when determining use, the economic burden with high-cost medication, predictive biomarkers, tumor location, patient geographic location, patient quality of life, and the prevention of debilitating adverse effects. CRC remains a common malignancy, with many of these patients expected to receive targeted therapy, including EGFR mAb therapy. Oncologists must recognize these EGFR mAb factors in order to improve outcomes. This review aims to provide a chronological timeline on the development of panitumumab, clinical pearls, and guidance on the current use of panitumumab in mCRC.

Abstract 880: Mapping the metastatic colorectal cancer phospho-proteome for predicting response to cetuximab

Abstract Introduction: The discovery of the key role of the epidermal growth factor receptor (EGFR) and its downstream signaling effectors in the pathophysiology of colorectal cancer (CRC) has resulted in the clinical use of targeted therapies in the treatment of metastatic CRC (mCRC). However, clinical benefit to EGFR blockade is observed in only a subgroup of CRC patients wild type for KRAS andNRAS. Genomic characterization of patient derived xenograft (PDX) models of mCRC have revealed additional resistance mechanisms to the EGFR MAb cetuximab including amplification of MET, HER2 and mutations in ERBB2, EGFR, FGFR1, PDGFRA, and MAP2K1 (Bertotti et al. 2011, 2015). However, not all resistance is understood and the biochemical signaling correlates of sensitivity and resistance remain incompletely understood. Phosphoproteomics allows for comprehensive protein phosphorylation profiling, and thereby may shed new insights into the biology of CRC and the molecular basis of cetuximab response. Aim: To identify aberrant signaling pathways, predictive biomarkers, and alternative drug targets in genomically-annotated CRC PDX models by mass spectrometry-based phosphoproteomics. Methods: We performed LC-MS/MS based phosphoproteome profiling (van der Mijn et al. 2015; Piersma et al. 2015) on untreated CRC PDX models lacking KRAS, NRAS or BRAF mutation (n = 20). For comparison, KRAS, BRAF or NRAS-mutant and MET or HER2 amplified models (n = 21) were analyzed. Phosphopeptides were captured by phosphotyrosine antibodies and titanium dioxide. MS/MS data was searched using MaxQuant. Phosphoproteome data (ion intensities and spectral counts) were correlated with drug sensitivity. Dedicated bioinformatics was used to identify hyperactive kinases and signaling pathways in individual tumors. Results: The dataset contained 13.418 tyrosine-, serine- and threonine-phosphorylated peptides derived from 4588 proteins, including 237 phosphorylated kinases. Unsupervised hierarchical clustering of phosphopeptide intensities revealed subclusters enriched for sensitive and resistant models. Among cetuximab-resistant models, HER2 and MET were identified as hyperphosphorylated and hyperactive driver kinases, confirming the genomic annotation. Sensitivity to combination treatment of both EGFR and driver kinases was observed previously, providing proof-of-principle of the use of phosphoproteomics for the identification of driver kinases. Conclusion/Future: This project is uncovering the phosphoproteomic landscape of colorectal tumors and will yield a better understanding of signaling pathways involved, with an emphasis on identifying activated drug targets and predictive biomarkers in this disease, in relation to KRAS/NRAS/BRAF status and response to anti-EGFR therapy. Citation Format: Robin Beekhof, Mariette Labots, Jaco C. Knol, Tim R.A. Schelfhorst, Nicole van Grieken, Sander R. Piersma, Thang V. Pham, Andrea Bertotti, Livio Trusolino, Henk M.W. Verheul, Connie R. Jiménez. Mapping the metastatic colorectal cancer phospho-proteome for predicting response to cetuximab. [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 880.

Treatment dilemmas of cetuximab combined with chemotherapy for metastatic colorectal cancer.

Although monoclonal antibodies (mAbs) against epidermal growth factor receptor (EGFR) have largely enriched the available therapeutic choices for colorectal cancer (CRC), the understanding and management of their associated clinical toxicities are limited. In addition, the combined strategies of administering EGFR mAbs and traditional cytotoxic agents, such as 5-fluorouracil, oxaliplatin and irinotecan, have resulted in a more complicated management of CRC treatment-related side effects compared with EGFR mAb monotherapy. We believe that a thorough recognition of the toxicities of EGFR mAb drugs is essential for physicians to increase the therapeutic index in the treatment of CRC. This review aims to summarize the existing information regarding the treatment dilemmas of cetuximab combined with chemotherapy in the management of metastatic CRC.

The Experimental Study on the Treatment of Cytokine-Induced Killer Cells Combined with EGFR Monoclonal Antibody Against Gastric Cancer

To investigate the antitumor activity of cytokine-induced killer (CIK) cells combined with epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) against gastric cancer cell line SGC7901. Immunocytochemistry assay was performed to detect the expression of EGFR in SGC7901 cell lines. The cytotoxicity activity of CIK cells combined with EGFR mAb was analyzed by the (51)Cr release assay. Then, the comparison of the cytotoxicity activity between CIK cells combined with EGFR mAb and CIK cells combined with CD3 mAb and CIK cells was conducted. Antitumor activity of CIK cells combined with EGFR mAb in vivo was analyzed by tumor growth assay and tumor reduction assay. The cell lysis rate of CIK cells combined with EGFR mAb was higher than those of CIK cells combined with CD3 mAb and CIK cells only (p<0.05). The lysis rates of the latter two groups were not different. The antitumor activity of CIK cells combined with EGFR mAb was higher than those of other groups in vivo (p<0.05). It was suggested in the current study that EGFR mAb could enhance the antitumor ability of CIK cells to bind and kill the gastric cancer cells in vitro and in vivo.

A case of penile squamous cell carcinoma treated with a combination of antiepidermal growth factor receptor antibody and chemotherapy

Our previous study showed that the features of epidermal growth factor receptor (EGFR)-RAS signaling in penile squamous cell carcinoma (SCC) suggested potential benefits of anti-EGFR monoclonal antibodies (mAbs) for penile SCC. Here, we report, for the first time, a combination of nimotuzumab (an EGFR mAb) with chemotherapy that resulted in a partial response in a 44-year-old patient with penile SCC, who developed bilateral inguinal node metastasis after primary partial penile amputation. The literature of case reports of anti-EGFR mAbs in penile SCC was also reviewed.

Strategies to overcome resistance to epidermal growth factor receptor monoclonal antibody therapy in metastatic colorectal cancer.

Administration of monoclonal antibodies (mAbs) against epidermal growth factor receptor (EGFR) such as cetuximab and panitumumab in combination with conventional chemotherapy substantially prolongs survival of patients with metastatic colorectal cancer (mCRC). However, the efficacy of these mAbs is limited due to genetic variation among patients, in particular K-ras mutations. The discovery of K-ras mutation as a predictor of non-responsiveness to EGFR mAb therapy has caused a major change in the treatment of mCRC. Drugs that inhibit transformation caused by oncogenic alterations of Ras and its downstream components such as BRAF, MEK and AKT seem to be promising cancer therapeutics as single agents or when given with EGFR inhibitors. Although multiple therapeutic strategies to overcome EGFR mAb-resistance are under investigation, our understanding of their mode of action is limited. Rational drug development based on stringent preclinical data, biomarker validation, and proper selection of patients is of paramount importance in the treatment of mCRC. In this review, we will discuss diverse approaches to overcome the problem of resistance to existing anti-EGFR therapies and potential future directions for cancer therapies related to the mutational status of genes associated with EGFR-Ras-ERK and PI3K signalings.

Which is false: Oxaliplatin or fluoropyrimidine? An analysis of patients with KRAS wild‐type metastatic colorectal cancer treated with first‐line epidermal growth factor receptor monoclonal antibody

This meta-analysis was performed to determine whether the addition of monoclonal antibodies (mAbs) of epidermal growth factor receptor (EGFR) to oxaliplatin-based chemotherapy treatment improves efficacy in KRAS wild-type metastatic colorectal cancer (mCRC), and whether infusional 5-fluorouracil (5-FU) and oxaliplatin is a preferred combination for EGFR mAbs. Oxaliplatin (including treatment), EGFR mAbs, first-line treatment, KRAS wild-type, and mCRC were used as key words. The PRIME, OPUS, COIN, and NORDIC VII trials were identified by two independent authors. Time-to-event outcomes of overall survival (OS) and progression-free survival (PFS) were analyzed using HRs (hazard ratios) with fixed effect, and response rate (RR) using odd ratios (OR) with fixed effect. A total of 1767 patients who were KRAS wild-type were included in this meta-analysis, with 866 patients in the mAbs and chemotherapy combination group and 901 patients in the chemotherapy alone group. The addition of mAbs to oxaliplatin-based chemotherapy in patients with KRAS wild-type mCRC as first-line treatment resulted in significant improvements in PFS (HR = 0.88; 95% confidence interval (CI), 0.79-0.99; P = 0.03) and response rate (RR) (OR = 1.38; 95% CI, 1.14-1.66; P = 0.009) compared with chemotherapy alone, but the difference in OS was not significant (HR = 0.96; 95% CI, 0.85-1.08; P = 0.48). However, the differences in OS and PFS were not significant when mAbs were added to bolus 5-FU or capecitabine-based regimens compared with chemotherapy alone, whereas PFS improved with an infusional 5-FU and oxaliplatin combination (P = 0.06; PFS, HR = 0.76; 95% CI, 0.65-0.86; P = 0.0002), and even OS was marginally significant, which was consistent with the subgroup analysis of cetuximab and panitumumab. EGFR mAbs combined with oxaliplatin and an infusional 5-FU regimen was associated with significantly improved RR, PFS and OS as first-line treatment in KRAS wild-type mCRC.

Is oxaliplatin a good partner for EGFR monoclonal antibodies as first-line treatment in KRAS wild-type metastatic colorectal cancer? A meta-analysis.

e14645 Background: This meta-analysis was performed to determine whether the addition of monoclonal antibodies (mAbs) of epidermal growth factor receptor (EGFR) to oxaliplatin-based chemotherapy treatment improves efficacy in KRAS wild-type metastatic colorectal cancer (mCRC), and whether infusional 5-fluorouracil (5-FU) and oxaliplatin is a preferred combination for EGFR mAbs. Methods: Oxaliplatin (including treatment), EGFR mAbs, first-line treatment, KRAS wild-type, and mCRC were used as key words. The PRIME, OPUS, COIN, and NORDIC VII trials were identified by two independent authors. Time-to-event outcomes of overall survival (OS) and progression-free survival (PFS) were analyzed using HRs (Hazard Ratios) with fixed effect, and response rate (RR) using odd ratios (OR) with fixed effect. Results: A total of 1,767 patients who were KRAS wild-type were included in this meta-analysis, with 866 patients in the mAbs and chemotherapy combination group and 901 patients in the chemotherapy alone group. The addition of mAbs to oxaliplatin-based chemotherapy in patients with KRAS wild-type mCRC as first-line treatment resulted in significant improvements in PFS (HR=0.88; 95% confidence interval (CI), 0.79 to 0.99; P=0.03) and response rate (RR) (OR = 1.38; 95% CI, 1.14 to 1.66; P = 0.009) compared with chemotherapy alone, but the difference in OS was not significant (HR=0.96; 95% CI, 0.85 to 1.08; P=0.48). However, the differences neither in OS nor in PFS were not significant when mAbs were added to bolus 5-FU or capecitabine-based regimens compared with chemotherapy alone, whereas PFS improved with an infusional 5-FU and oxaliplatin combination (P=0.06; PFS, HR=0.76; 95% CI, 0.65 to 0.86; P=0.0002), and even OS was marginally significant. Conclusions: Oxaliplatin and infusional 5-FU regimen tends to be a better backbone combination with EGFR mAbs as first-line treatment in KRAS wild-type mCRC.

Impact of Epidermal Growth Factor Receptor (EGFR) Cell Surface Expression Levels on Effector Mechanisms of EGFR Antibodies

The epidermal growth factor receptor (EGFR) is a widely expressed Ag that is successfully targeted in tumor patients by mAbs or tyrosine kinase inhibitors. A clinical study in non-small cell lung cancer patients demonstrated a positive correlation between EGFR expression levels and the therapeutic efficacy of the EGFR mAb cetuximab. However, the impact of EGFR expression on the different mechanisms of action (MoAs) triggered by the EGFR mAb has not been defined. In this study, BHK-21 cells were stably transfected to express different EGFR levels, which were quantified by immunofluorescence and immunohistochemistry and compared with EGFR levels of clinical non-small cell lung cancer samples. These cells were used to systematically investigate the impact of target Ag expression levels on Fab- or Fc-mediated MoAs of EGFR mAb. A negative correlation between EGFR levels and potency of Fab-mediated MoA was observed. Interestingly, Ab-dependent cell-mediated cytotoxicity (ADCC) by NK cells, monocytes, or polymorphonuclear cells as well as complement-dependent cytotoxicity positively correlated with the number of EGFR molecules. In comparison with ADCC by mononuclear cells, polymorphonuclear cell-mediated ADCC and complement-dependent cytotoxicity required higher EGFR expression levels and higher mAb concentrations to trigger significant tumor cell killing. This correlation between EGFR expression levels and Fc-mediated MoA was confirmed in an independent panel of human tumor cell lines carrying diverse genetic alterations. Furthermore, RNA interference-induced knockdown experiments reinforced the impact of EGFR expression on tumor cell killing by EGFR mAb. In conclusion, these results suggest that EGFR expression levels may determine distinct patterns of MoAs that contribute to the therapeutic efficacy of EGFR mAb.

EGFR expression is linked to osteopontin and Nf-κB signaling in clear cell renal cell carcinoma

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase involved in many important aspects of cell biology that are related to tumorigenesis. There are opposite evidences of the role of EGFR in renal cancer and the outcome of EGFR-targeted therapies, suggesting the complexity of EGFR signaling pathways. In vitro, osteopontin (OPN) and nuclear factor kappa B (NF-κB) are thought to be involved in specific ligand-independent EGFR activation that could have a role in resistance to EGFR mAb therapy. Aim of this study was to analyze the relationship between EGFR and OPN at the protein and mRNA level, as well as their relation to NF-κB in clear cell renal cell carcinoma (CCRCC). Expression of EGFR, OPN, and p65 NF-κB protein was analyzed using immunohistochemistry and compared mutually in 88 CCRCC samples. Expression of EGFR and OPN mRNAs was analyzed using quantitative Real-time PCR in 22 CCRCC samples and compared mutually and with NF-κB protein expression. Epidermal growth factor receptor mRNA level was higher in CCRCC samples in comparison with normal renal tissue (p=0.012) and was associated with high OPN mRNA level, and with NF-κB activation (p<0.001 and p=0.045, respectively). Immunohistochemical staining showed the inverse association; high EGFR protein expression was related with low OPN and NF-κB protein expression (p<0.001 and p=0.047, respectively). Epidermal growth factor receptor gene is upregulated in CRCC and associated with OPN gene expression and NF-kB signaling. The inverse relation between OPN and EGFR at the protein level could probably reflect dynamic changes that EGFR undergoes following activation.

Phase II trial of preoperative radiotherapy (RT) and panitumumab (PAN) in KRAS wild type (wt) rectal cancer (RC).

e14060 Background: The addition of anti Epidermal Growth Factor Receptor (EGFR) monoclonal antibodies (mabs) to preoperative chemoradiation in RC has produced low pathological complete response (pCR) rate. The postulated reasons for the poor outcome are: lack of patient selection, suboptimal treatment sequencing, and potential negative interaction between anti EGFR mabs and chemotherapy (CT) when used concurrently as radiosensitizers. Given these issues, we conducted a phase II trial of PAN in combination with preoperative RT in Kras wt RC. Methods: We studied several treatment sequences in murine models of Kras wt human colorectal cancer. Next, we used our preclinical results to design the treatment schedule of the phase II trial. PAN (6mg/kg/q2w) was combined with RT (45 Gy) to treat T3-4, Kras wt RC. Surgery was done 6-8 weeks after the end of RT. The primary endpoint, the pCR rate on surgical specimen, was assessed centrally (Simon: H0=5%, H1=17%, α=0.05, β=0.2). Results: In our murine models, the addition of anti EGFR mabs to RT significantly improved response when anti EGFR mabs were started during RT and extended after the end of RT (p&lt;0.05). No benefit was found when anti EGFR mabs were given before the start of RT. In the phase II trial, we therefore started RT on day 1 and introduced PAN 7 days later (day 8). After RT ended (day 36), PAN treatment was continued to day 50. To fully explore PAN’s potential as radiosensitizer, CT was not given during RT but postoperatively. 19 patients were evaluable for pCR. 47% of tumours were cT3N+. Hypomagnesemia (16%) and hypophosphatemia (16%) were most common grade ≥3 toxicities. As no pCR was found, the study was closed prematurely for lack of efficacy according to the statistical rule. 7 patients (41%) had &gt;50% pathological tumour regression (grade 3 Dworak) and 12 (70%) showed &gt;2mm of tumour-free circumferential resection margin. Conclusions: Preclinical data confirm the need of optimal treatment sequencing to potentiate synergism between anti EGFR mabs and RT. However, the pCR rate in our phase II trial remains low despite adequate patient selection and optimized study design. Thus, we do not recommend the concurrent use of anti EGFR mabs and RT in the neoadjuvant treatment of RC.

Explaining the Unexplainable: EGFR Antibodies in Colorectal Cancer

Cetuximab and panitumumab, monoclonal antibodies (mAbs) against the epidermal growth factor receptor (EGFR), have demonstrated efficacy in the treatment of advanced colorectal cancer as single agents and in combination with conventional chemotherapy. Since the US Food and Drug Administration approval of cetuximab in 2004 and panitumumab in 2006, EGFR mAbs have become standard components of treatment algorithms for this disease. The discovery of KRAS mutations as a negative predictive marker for this class of agents in colorectal cancer has rapidly been integrated into clinical practice and has opened the door for a new era in translational and clinical research. In KRAS wild-type colorectal cancer, EGFR mAbs have documented activity in various therapeutic settings and have been successfully combined with different chemotherapy backbones in randomized trials, including irinotecanand oxaliplatin-based regimens. Until recently, the body of evidence from randomized trials suggested that (1) EGFR mAbs as single agents or in combination with chemotherapy showed activity only in KRAS wild-type colorectal cancer; (2) the observed improvement of progression-free survival (PFS) was independent of the line of therapy in which the EGFR mAb was used; (3) the increased response rate with EGFR mAbs in patients with KRAS wild-type tumors was observed even in trials that did not meet their time-related end points of PFS or overall survival (OS); and (4) cetuximab and panitumumab had interchangeable activity. Several questions remained, however, despite extensive clinical experience with EGFR antibodies. The negative data of the large COIN (Continuous Chemotherapy Plus Cetuximab, or Intermittent Chemotherapy With Standard Continuous Palliative Combination Chemotherapy With Oxaliplatin and a Fluoropyrimidine in First-Line Treatment of Metastatic Colorectal Cancer) trial, which investigated cetuximab added to an oxaliplatin-based chemotherapy backbone, seemed to contrast with the positive data of the CRYSTAL (Cetuximab Combined With Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer) trial, which used an irinotecan-based regimen. These findings suggested that there may be a preferred chemotherapy partner for EGFR antibodies. In addition, the randomized phase II trial, OPUS (Oxaliplatin and Cetuximab in First-Line Treatment of Metastatic Colorectal Cancer), demonstrated that the use of cetuximab in combination with oxaliplatin-based treatment for KRAS-mutated colorectal cancer appeared to have a detrimental effect. Eventually, the well-conducted first-line phase III PRIME (Panitumumab Randomized Trial in Combination With Chemotherapy for Metastatic Colorectal Cancer to Determine Efficacy) trial, which investigated the addition of panitumumab to infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX), appeared to clarify the situation by demonstrating that in KRAS wild-type cancers, an EGFR mAb can indeed add efficacy to a FOLFOX backbone. In addition, PRIME also confirmed that, in KRAS-mutated colorectal cancers, the use of an EGFR mAb added to chemotherapy can decrease efficacy. Although this detrimental effect in KRAS-mutated cancers was initially thought to be linked only to an oxaliplatin-based chemotherapy backbone, recently presented data from the second-line phase III trial PICCOLO (Panitumumab, Irinotecan & Ciclosporin in Colorectal Cancer Therapy; irinotecan with or without panitumumab) demonstrated a similar negative effect on PFS and response rate in this group of patients. In the adjuvant setting, the addition of cetuximab to FOLFOX did not improve outcomes in stage III colon cancer, not even in patients with KRASwild-typetumors. InKRAS-mutatedstageIIIcancers, cetuximab was associated with inferior outcome, mirroring the detrimental effect observed in some trials in the metastatic setting. The most recent National Comprehensive Cancer Network guidelines suggest that cetuximab should be not combined with oxaliplatin. The guidelines, however, somewhat inconsistently do allow the use of panitumumab in combination with FOLFOX, on the basis of results from the PRIME trial. The NORDIC (5-Fluorouracil/Folinate/Oxaliplatin [Eloxatin] [FLOX Regimen] Given Continuously or Intermittently, in Combination With Cetuximab [Erbitux] in First-Line Treatment of Metastatic Colorectal Cancer) trial published in this issue of Journal of Clinical Oncology now adds another layer of confusion to the already complex and somewhat inconsistent results on the use of EGFR mAbs in colorectal cancer. In this first-line phase III study, cetuximab was added to bolus fluorouracil (FU)/leucovorin plus oxaliplatin (FLOX), a combination regimen commonly used in Scandinavia, but not in other parts of the world. The primary end point of the trial was PFS, with secondary end points of OS, response rate, R0-resection rate of metastases, and safety. During the conduct of the trial, KRAS mutation emerged as a negative predictive marker for EGFR mAbs, and a prospective KRAS status–based outcomes analysis was integrated into the trial, but no adjustment of the sample size was performed. In the end, the number of patients in the two main comparison arms, FLOX with JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 30 NUMBER 15 MAY 2