Preclinical and clinical evaluations of ABX-EGF, a fully human anti-epidermal growth factor receptor antibody

Adjuvant Auger Electron-Emitting Radioimmunotherapy with [111In]In-DOTA-Panitumumab in a Mouse Model of Local Recurrence and Metastatic Progression of Human Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) has a high risk for recurrence and metastasis. We studied the effectiveness of Auger electron (AE) radioimmunotherapy (RIT) with antiepidermal growth factor receptor (EGFR) panitumumab conjugated with DOTA complexed to 111In ([111In]In-DOTA-panitumumab) for preventing metastatic progression after local treatment of 231/LM2-4 Luc+ human TNBC tumors in the mammary fat pad of NRG mice. Prior to RIT, the primary tumor was resected, and tumor margins were treated with X-irradiation (XRT; 5 days × 6 Gy/d). RIT was administered 1 day post-XRT by intravenous injection of 26 MBq (15 μg) or 2 × 10 MBq (15 μg each) separated by 7 d. These treatments were compared to tumor resection with or without XRT combined with DOTA-panitumumab (15 μg) or irrelevant [111In]In-DOTA-IgG2 (24 MBq; 15 μg), and efficacy was evaluated by Kaplan-Meier survival curves. The effect of [111In]In-DOTA-panitumumab (23 MBq; 15 μg) after tumor resection without local XRT was also studied. Tumor resection followed by XRT and RIT with 26 MBq [111In]In-DOTA-panitumumab significantly increased the median survival to 35 d compared to tumor resection with or without XRT (23-24 d; P < 0.0001). Local treatment with tumor resection and XRT followed by 2 × 10 MBq of [111In]In-DOTA-panitumumab, DOTA-panitumumab, or [111In]In-DOTA-IgG2 did not significantly improve median survival (26 days for all treatments). RIT alone with [111In]In-DOTA-panitumumab postresection of the tumor without XRT increased median survival to 29 days, though this was not significant. Despite significantly improved survival in mice treated with tumor resection, XRT, and RIT with [111In]In-DOTA-panitumumab, all mice eventually succumbed to advanced metastatic disease by 45 d post-tumor resection. SPECT/CT with [111In]In-DOTA-panitumumab, PET/MRI with [64Cu]Cu-DOTA-panitumumab F(ab')2, and PET/CT with [18F]FDG were used to detect recurrent and metastatic disease. Uptake of [111In]In-DOTA-panitumumab at 4 d p.i. in the MFP tumor was 26.8 ± 9.7% ID/g and in metastatic lymph nodes (LN), lungs, and liver was 34.2 ± 26.9% ID/g, 17.5 ± 6.0% ID/g, and 9.4 ± 2.4%ID/g, respectively, while uptake in the lungs (6.0 ± 0.9% ID/g) and liver (5.2 ± 2.9% ID/g) of non-tumor-bearing NRG was significantly lower (P < 0.05). Radiation-absorbed doses in metastatic LN, lungs, and liver were 9.7 ± 6.1, 6.4 ± 2.1, and 10.9 ± 2.7 Gy, respectively. In conclusion, we demonstrated that RIT with [111In]In-DOTA-panitumumab combined with tumor resection and XRT significantly improved the survival of mice with recurrent TNBC. However, the aggressive nature of 231/LM2-4 Luc+ tumors in NRG mice may have contributed to the tumor recurrence and progression observed.

Relative Biological Effectiveness (RBE) of [64Cu]Cu and [177Lu]Lu-NOTA-panitumumab F (ab')2 radioimmunotherapeutic agents vs. γ-radiation for decreasing the clonogenic survival in vitro of human pancreatic ductal adenocarcinoma (PDAC) cells

INTRODUCTION

Our objective was to compare [64Cu]Cu-NOTA-panitumumab F(ab')2 and [177Lu]Lu-NOTA-panitumumab F(ab')2 radioimmunotherapy (RIT) agents for decreasing the clonogenic survival fraction (SF) in vitro of EGFR-positive human pancreatic ductal adenocarcinoma (PDAC) cell lines and estimate the relative biological effectiveness (RBE) vs. γ-radiation (XRT).

METHODS

EGFR-positive PDAC cell lines (AsPC-1, PANC-1, MIAPaCa-2, Capan-1) and EGFR-knockout PANC-1 EGFR KO cells were treated in vitro for 18 h with (0-19.65 MBq; 72 nmols/L) of [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 or XRT (0-8 Gy) followed by clonogenic assay. The SF was determined after culturing single treated cells for 14 d. Cell fractionation studies were performed for cells incubated with 1 MBq (72 nmols/L) of [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 for 1, 4, or 24 h to estimate the time-integrated activity (Ã) on the cell surface, cytoplasm, nucleus and medium. Radiation absorbed doses in the nucleus were calculated by multiplying à by S-factors calculated by Monte Carlo N Particle (MCNP) modeling using monolayer cell culture geometry. The SF of PDAC cells was plotted vs. dose and fitted to a linear quadratic model to estimate the dose required to decrease the SF to 0.1 (D10). The D10 for RIT agents were compared to XRT to estimate the RBE. DNA double-strand breaks (DSBs) caused by [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 continuous exposure for 5 h or 20 h were probed by immunofluorescence for γ-H2AX. Relative EGFR expression of PDAC cells was assessed by flow cytometry (scored + to +++) and cell doubling times for untreated cells were determined.

RESULTS

The D10 for [64Cu]Cu-NOTA-panitumumab F(ab')2 ranged from 9.1 Gy (PANC-1) to 39.9 Gy (Capan-1). The D10 for [177Lu]Lu-NOTA-panitumumab F(ab')2 ranged from 11.7 Gy (AsPC-1) to 170.8 Gy (Capan-1). The D10 for XRT ranged from 2.5 Gy (Capan-1) to 6.7 Gy (PANC-1 EGFR KO). D10 values were not correlated with EGFR expression over a relatively narrow range (++ to +++) or with cell doubling times. Based on D10 values, PANC-1 EGFR KO cells were 1.6-fold less sensitive than PANC-1 cells to [64Cu]Cu-NOTA-panitumumab F(ab')2 and 1.9-fold less sensitive to [177Lu]Lu-NOTA-panitumumab F(ab')2. The RBE for [64Cu]Cu-NOTA-panitumumab F(ab')2 ranged from 0.06 for Capan-1 cells to 0.45 for PANC-1 cells. The RBE for [177Lu]Lu-NOTA-panitumumab F(ab')2 ranged from 0.015 for Capan-1 cells to 0.28 for AsPC-1 cells. DNA DSBs were detected in PDAC cells exposed to [64Cu]Cu-NOTA-panitumumab F(ab')2 or [177Lu]Lu-NOTA-panitumumab F(ab')2 but were not correlated with the SF of the cells.

CONCLUSIONS

We conclude that at the same dose delivered to the cell nucleus [64Cu]Cu-NOTA-panitumumab F(ab')2 and [177Lu]Lu-NOTA-panitumumab F(ab')2 were less radiobiologically effective than XRT for decreasing the SF of human PDAC cells, but [64Cu]Cu-NOTA-panitumumab F(ab')2 was more cytotoxic than [177Lu]Lu-NOTA-panitumumab F(ab')2 except for AsPC-1 cells which were more sensitive to [177Lu]Lu-NOTA-panitumumab F(ab')2.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

This study demonstrates that higher radiation doses may be required for RIT than XRT to achieve radiobiologically equivalent effects when used to treat PDAC.

The potential effect of Schisandrin-B combination with panitumumab in wild-type and mutant colorectal cancer cell lines: Role of apoptosis and autophagy

Panitumumab is an approved monoclonal antibody for the treatment of colorectal cancer (CRC); however, mutations in EGFR signaling pathway resulted in poor response. Schisandrin-B (Sch-B) is a phytochemical that was suggested to protect against inflammation, oxidative stress, and cell proliferation. The present study aimed to investigate the potential effect of Sch-B on panitumumab-induced cytotoxicity in wild-type Caco-2, and mutant HCT-116 and HT-29 CRC cell lines, and the possible underlying mechanisms. CRC cell lines were treated with panitumumab, Sch-B, and their combination. The cytotoxic effect of drugs was determined by MTT assay. The apoptotic potential was assessed in-vitro by DNA fragmentation and caspase-3 activity. Additionally, autophagy was investigated via microscopic detection of autophagosomes and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) measurement of Beclin-1, Rubicon, LC3-II, and Bcl-2 expression. The drug pair enhanced panitumumab cytotoxicity in all CRC cell lines where IC50 of panitumumab was decreased in Caco-2 cell line. Apoptosis was induced through caspase-3 activation, DNA fragmentation, and Bcl-2 downregulation. Caco-2 cell line treated with panitumumab showed stained acidic vesicular organelles, contrariwise, all cell lines treated with Sch-B or the drug pair displayed green fluorescence indicating the lack of autophagosomes. qRT-PCR revealed the downregulation of LC3-II in all CRC cell lines, Rubicon in mutant cell lines, and Beclin-1 in HT-29 cell line only. Sch-B at 6.5 µM promoted panitumumab-induced apoptotic cell death, in-vitro, via caspase-3 activation and Bcl-2 downregulation, rather than autophagic cell death. This novel combination therapy against CRC, allows the reduction of panitumumab dose to guard against its adverse effects.

Autophagy awakens-the myriad roles of autophagy in head and neck cancer development and therapeutic response

Autophagy is an evolutionarily conserved cell survival mechanism that degrades damaged proteins and organelles to generate cellular energy during times of stress. Recycling of these cellular components occurs in a series of sequential steps with multiple regulatory points. Mechanistic dysfunction can lead to a variety of human diseases and cancers due to the complexity of autophagy and its ability to regulate vital cellular functions. The role that autophagy plays in both the development and treatment of cancer is highly complex, especially given the fact that most cancer therapies modulate autophagy. This review aims to discuss the balance of autophagy in the development, progression, and treatment of head and neck cancer, as well as highlighting the need for a deeper understanding of what is still unknown about autophagy.

Therapeutic applications of herbal/synthetic/bio-drug in oral cancer: An update

Oral cancer, as one of the most prevalent and invasive cancers that invade local tissue, can cause metastasis, and have high mortality. In 2018, around 355,000 worldwide oral cancers occurred and resulted in 177,000 deaths. Estimates for the year 2020 include about 53,260 new cases added to previous year's cases, and the estimated death toll from this cancer in 2020 is about 10,750 deaths more than previous years. Despite recent advances in cancer diagnosis and treatment, unfortunately, 50% of people with cancer cannot be cured. Of course, it should be remembered that the type of treatment used greatly influences patient recovery. There are not many choices when it comes to treating oral cancer. Research efforts focusing on the discovery and evolution of innovative therapeutic approaches for oral cancer are essential. Such traditional methods of treating this type of cancer like surgery and chemotherapy, have evolved dramatically during the past thirty to forty years, but they continue to cause panic among patients due to their side effects. Therefore, it is necessary to study and use drugs that are less risky for the patient as well as to provide solutions to reduce chemotherapy-induced adverse events that prevent many therapeutic risks. As mentioned above, this study examines low-risk therapies such as herbal remedies, biological drugs, and synthetic drugs in the hope that they will be useful to physicians, researchers, and scientists around the world.

Radiochemotherapy with or without cetuximab for unresectable esophageal cancer: final results of a randomized phase 2 trial (LEOPARD-2)

Purpose

To investigate the efficacy and toxicity of cetuximab when added to radiochemotherapy for unresectable esophageal cancer.

Methods

This randomized phase 2 trial (clinicaltrials.gov, identifier NCT01787006) compared radiochemotherapy plus cetuximab (arm A) to radiochemotherapy (arm B) for unresectable esophageal cancer. Primary objective was 2‑year overall survival (OS). Arm A was considered insufficiently active if 2‑year OS was ≤40% (null hypothesis = H₀), and promising if the lower limit of the 95% confidence interval was >45%. If that lower limit was >40%, H₀ was rejected. Secondary objectives included progression-free survival (PFS), locoregional control (LC), metastases-free survival (MFS), response, and toxicity. The study was terminated early after 74 patients; 68 patients were evaluable.

Results

Two-year OS was 71% in arm A (95% CI: 55–87%) vs. 53% in arm B (95% CI: 36–71%); H₀ was rejected. Median OS was 49.1 vs. 24.1 months (p = 0.147). Hazard ratio (HR) for death was 0.60 (95% CI: 0.30–1.21). At 2 years, PFS was 56% vs. 44%, LC 84% vs. 72%, and MFS 74% vs. 54%. HRs were 0.51 (0.25–1.04) for progression, 0.43 (0.13–1.40) for locoregional failure, and 0.43 (0.17–1.05) for distant metastasis. Overall response was 81% vs. 69% (p = 0.262). Twenty-six and 27 patients, respectively, experienced at least one toxicity grade ≥3 (p = 0.573). A significant difference was found for grade ≥3 allergic reactions (12.5% vs. 0%, p = 0.044).

Conclusion

Given the limitations of this trial, radiochemotherapy plus cetuximab was feasible. There was a trend towards improved PFS and MFS. Larger studies are required to better define the role of cetuximab for unresectable esophageal cancer.

Efficacy and safety of anti-EGFR monoclonal antibodies combined with different chemotherapy regimens in patients with RAS wild-type metastatic colorectal cancer: A meta-analysis

OBJECTIVES

To investigate the efficacy and safety of adding anti-epidermal growth factor receptor [EGFR] MoAbs to various chemotherapy regimens in patients with RAS wild-type metastasized colorectal cancer (RAS WT metastatic colorectal cancer [mCRC]) and to identify the optimal combination regimens.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL from the inception date to 20th May 2019. Randomized clinical trials investigating chemotherapy with or without anti-EGFR MoAbs in treatment of patients with RAS WT mCRC were included.

RESULTS

Eighteen studies involving 8848 participants were eligible. Comparing with oxaliplatin-based chemotherapy, adding anti-EGFR MoAbs benefited only in progression-free survival (PFS) (hazard ratio [HR] = 0.80, 95% confidence interval [CI]: 0.67 to 0.94), but not in overall survival (OS) (HR = 0.89, 95% CI: 0.78 to 1.02). Further sensitivity analysis indicated that adding anti-EGFR MoAbs to FOLFOLX regimen as a first-line treatment showed benefits in both PFS and OS (PFS: HR = 0.74, 95% CI: 0.64 to 0.84; OS: HR = 0.83, 95% CI: 0.73 to 0.95, respectively). Comparing with irinotecan-based chemotherapy or best supportive care, adding anti-EGFR MoAbs revealed an improvement in both PFS (HR = 0.77, 95% CI: 0.69 to 0.86; HR = 0.46, 95% CI: 0.40 to 0.54, respectively) and OS (HR = 0.89, 95% CI: 0.80 to 0.98; HR = 0.65, 95% CI: 0.54 to 0.78, respectively).

CONCLUSION

Anti-EGFR MoAbs as a monotherapy or in combination with either irinotecan-based chemotherapy or FOLFOX in patients with RAS wild-type mCRC have better response and survival outcome, whereas OS does not benefit from adding anti-EGFR MoAbs to another oxaliplatin-based regimen. Anti-EGFR MoAbs have increased the risk of adverse effects than chemotherapy alone. More high-quality randomized controlled trials for RAS wild type are necessary.

Clinical Pharmacokinetics and Pharmacodynamics of the Epidermal Growth Factor Receptor Inhibitor Panitumumab in the Treatment of Colorectal Cancer

Despite progress in the treatment of metastatic colorectal cancer (mCRC) in the last 15 years, it is still a condition with a relatively low 5-year survival rate. Panitumumab, a fully human monoclonal antibody directed against the epidermal growth factor receptor (EGFR), is able to prolong survival in patients with mCRC. Panitumumab is used in different lines of therapy in combination with chemotherapy, and as monotherapy for the treatment of wild-type (WT) RAS mCRC. It is administered as an intravenous infusion of 6 mg/kg every 2 weeks and has a t_½ of approximately 7.5 days. Elimination takes place via two different mechanisms, and immunogenicity rates are low. Only RAS mutations have been confirmed as a negative predictor of efficacy with anti-EGFR antibodies. Panitumumab is generally well tolerated and has a manageable toxicity profile, despite a very high prevalence of dermatologic side effects. This article presents an overview of the clinical pharmacokinetics and pharmacodynamics of panitumumab, including a description of the studies that led to its approval in the different lines of therapy of mCRC.

Synthesis and Characterization of Cetuximab-Docetaxel and Panitumumab-Docetaxel Antibody-Drug Conjugates for EGFR-Overexpressing Cancer Therapy

The safety and efficacy of anticancer antibody-drug conjugates (ADCs) depend on the selection of tumor-targeting monoclonal antibody (mAb), linker, and drug, as well as their specific chemical arrangement and linkage chemistry. In this study, we used a heterobifunctional cross-linker to conjugate docetaxel (DX) to cetuximab (CET) or panitumumab (PAN). The resulting ADCs were investigated for their in vitro EGFR-specific cytotoxicity and in vivo anticancer activity. Reaction conditions, such as reducing agent, time, temperature, and alkylation buffer, were optimized to yield potent and stable ADCs with consistent batch-to-batch drug-to-antibody ratios (DARs). ADCs were synthesized with DARs from 0.4 to 3.0, and all retained their EGFR affinity and specificity after modification. ADCs were sensitive to cell surface wildtype EGFR expression, demonstrating more cytotoxicity in EGFR-expressing A431 and MDA-MB-231 cell lines compared to U87MG cells. A431 tumor-bearing mice treated once weekly for four weeks with 100 mg/kg cetuximab-docetaxel ADC (C-SC-DX, DAR 2.5) showed durable anticancer responses and improved overall survival compared to the same treatment regimen with 1 mg/kg DX, 100 mg/kg CET, or a combination 1 mg/kg DX and 100 mg/kg CET. New treatment options are emerging for patients with both wild-type and mutated EGFR-overexpressing cancers, and these studies highlight the potential role of EGFR-targeted ADC therapies as a promising new treatment option.

First-in-human study of the anti-HB-EGF antibody U3-1565 in subjects with advanced solid tumors

U3-1565 is a monoclonal antibody directed against heparin-binding epidermal growth factor-like growth factor (HB-EGF), which mediates angiogenesis via induction of vascular endothelial growth factor (VEGF-A). This first-in-human study characterized the safety, tolerability, efficacy, pharmacokinetics, and pharmacodynamics of U3-1565 in subjects with advanced solid tumors. In Part 1 (dose escalation following a modified 3 + 3 design), Cohorts 1-4, U3-1565 was administered at 2, 8, 16, and 24 mg/kg every 3 weeks for Cycle 1 and every 2 weeks thereafter. In Part 1, Cohort 5, and in Part 2 (dose expansion), U3-1565 was administered at 24 mg/kg every week. Thirty-six subjects were enrolled and treated (15 in Part 1; 21 in Part 2). No subject experienced dose limiting toxicity and maximum tolerated dose was not reached. All drug-related events were Grade 1 or 2 in severity, with fatigue and rash predominating. Following treatment with U3-1565, 1 subject with metastatic colorectal cancer experienced partial response and 6 subjects achieved stable disease. Four subjects completed the study main phase (first 12 cycles) and entered the extension phase. Of the 6/36 subjects with high (> 1500 pg/ml) baseline VEGF-A levels, all showed a decrease in VEGF-A (median - 60% [-22% to -97%]). Of the remaining subjects, only 19/30 showed a decrease (median - 18% [-2% to -82%]). Subjects with high VEGF-A baseline levels remained on treatment longer (3/6 entered study extension phase versus 1/30), and were more likely to show disease control (3/6 versus 4/30). In conclusion, U3-1565 demonstrates both proof of mechanism and clinical activity across different tumor types.

Phase II Study of Irinotecan Plus Panitumumab as Second-Line Therapy for Patients with Advanced Esophageal Adenocarcinoma

Lesson Learned.

Panitumumab plus irinotecan is not active for the treatment of esophageal adenocarcinoma.

Background.

Esophageal adenocarcinoma (EAC) is a lethal cancer with increasing incidence. Panitumumab (Pa) is a fully humanized IgG2 monoclonal antibody against human EGFR. Cetuximab (Cx) combined with irinotecan (Ir) is active for second‐line treatment of colorectal cancer. This phase II study was designed to evaluate Pa plus Ir as second‐line therapy for advanced EAC.

Methods.

The primary endpoint was response rate (RR). Patients with one prior treatment were given Pa 9 mg/m² on day 1 and Ir 125 mg/m² on days 1 and 8 of each 21‐day cycle. Inclusion criteria were confirmed EAC, measurable disease, no prior Ir or Pa, performance status <2, and normal organ function.

Results.

Twenty‐four patients were enrolled; 18 were eligible and evaluable. These patients were all white, with a median age of 62.5 years (range, 33–79 years), and included 15 men and 3 women. The median number of cycles was 3.5. The most common grade 1–2 adverse events were fatigue, diarrhea, anemia, leukopenia, and hypoalbuminemia. Grade 3–4 adverse events included hematologic, gastrointestinal, electrolyte, rash, fatigue, and weight loss. The median follow‐up was 7.2 months (range, 2.3–14 months). There were no complete remissions. The partial response rate was 6% (1/18; 95% confidence interval [CI], 0.01–0.26). The clinical benefit (partial response [PR] plus stable disease [SD]) rate was 50%. The median overall survival was 7.2 months (95% CI, 4.1–8.9) with an 11.1% 1‐year survival rate. The median progression‐free survival was 2.9 months (95% CI, 1.6–5.3).

Conclusion.

Irinotecan and panitumumab as second‐line treatment for advanced EAC are not active.

ADCC responses and blocking of EGFR-mediated signaling and cell growth by combining the anti-EGFR antibodies imgatuzumab and cetuximab in NSCLC cells

Imgatuzumab is a novel glycoengineered anti-epidermal growth factor receptor (EGFR) monoclonal antibody optimized to induce both antibody-dependent cellular cytotoxicity (ADCC) and EGFR signal transduction inhibition. We investigated anti-EGFR monoclonal antibodies imgatuzumab and cetuximab–induced internalization and membranous turnover of EGFR, and whether this affected imgatuzumab–mediated ADCC responses and growth inhibition of non-small cell lung cancer (NSCLC) cells.

In a panel of wild-type EGFR expressing human NSCLC cell lines, membranous and total EGFR levels were downregulated more effectively by imgatuzumab when compared with cetuximab. Imgatuzumab plus cetuximab enhanced EGFR internalization and reduced membranous turnover of EGFR, resulting in an even stronger downregulation of EGFR. Immunofluorescent analysis showed that combined treatment increased clustering of receptor-antibody complexes and directed internalized EGFR to lysosomes. The antibody combination potently inhibited intracellular signaling and epidermal growth factor (EGF)-dependent cell proliferation. More importantly, robust EGFR downregulation after 72 hours with the antibody combination did not impair ADCC responses.

In conclusion, imgatuzumab plus cetuximab leads to a strong downregulation of EGFR and superior cell growth inhibition in vitro without affecting antibody-induced ADCC responses. These findings support further clinical exploration of the antibody combination in EGFR wild-type NSCLC.

Pharmacology of Epidermal Growth Factor Inhibitors

Research into the molecular bases of malignant diseases has yielded the development of many novel agents with potential antitumor activity. Evidence for a causative role for the epidermal growth factor receptor (EGFR), which is now regarded as an excellent target for cancer chemotherapy in human cancer, leads to the development of EGFR inhibitors. Two classes of anti-EGFR agents are currently in clinical use: monoclonal antibodies directed at the extracellular domain of the receptor, and the low-molecular-weight receptor tyrosine kinase inhibitors acting intracellularly by competing with adenosine triphosphate for binding to the tyrosine kinase portion of the EGFR. The effect on the receptor interferes with key biological functions including cell cycle arrest, potentiation of apoptosis, inhibition of angiogenesis and cell invasion and metastasis. Cetuximab, a monoclonal antibody, and the receptor tyrosine kinase inhibitors gefitinib and erlotinib are currently approved for the treatment of patients with cancer. New agents with clinical activity are entering the clinic, and new combinatorial approaches are being explored with the aim of improving the potency and pharmacokinetics of EGFR inhibition, to increase the synergistic activity in combination with chemotherapy and overcome resistance to the EGFR inhibitors.

Targeted Therapies in the Treatment of Colorectal Cancers

Background:

In solid organ malignancies, no tumor type has seen a greater impact from the development of novel targeted therapies in 2004 than metastatic colorectal cancer.

Methods:

We review the current progress to date with the use of monoclonal antibodies in colorectal cancer and look at newer therapies under investigation.

Results:

Two monoclonal antibodies received Food and Drug Administration approval in early 2004, both for the indication of advanced, metastatic colorectal cancer. A large, randomized, placebo-controlled study demonstrated that the addition of a monoclonal antibody to vascular endothelial growth factor, bevacizumab, led to a statistically significant improvement in overall survival, with tolerable additional toxicity. Chimeric monoclonal antibody therapy directed at the epidermal growth factor receptor was associated with radiographic responses in a significant minority of patients with irinotecan-refractory colon cancer in a randomized phase II study of patients with irinotecan-refractory disease.

Conclusions:

These dramatic successes have led to further clinical studies of targeted therapy in colorectal cancer, making it one of the most promising areas of cancer research.

Therapeutic value of EGFR inhibition in CRC and NSCLC: 15 years of clinical evidence

Epidermal growth factor receptor (EGFR) plays a key role in tumour evolution, proliferation and immune evasion, and is one of the most important targets for biological therapy, especially for non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC). In the past 15 years, several EGFR antagonists have been approved for the treatment of NSCLC and metastatic CRC (mCRC). To optimise the use of anti-EGFR agents in clinical practice, various clinical and molecular biomarkers have been investigated, thus moving their indication from unselected to selected populations. Nowadays, anti-EGFR drugs represent a gold-standard therapy for metastatic NSCLC harbouring EGFR activating mutation and for RAS wild-type mCRC. Their clinical efficacy is limited by the presence of intrinsic resistance or the onset of acquired resistance. In this review, we provide an overview of the antitumour activity of EGFR inhibitors in NSCLC and CRC and of mechanisms of resistance, focusing on the development of a personalised approach through 15 years of preclinical and clinical research.

Profile of panitumumab as first-line treatment in patients with wild-type KRAS metastatic colorectal cancer

Targeted therapies against EGFR, vascular endothelial growth factor, and vascular endothelial growth factor receptor have expanded treatment options for patients with metastatic colorectal cancer (mCRC). Unfortunately, biomarkers to identify patients that are most likely to derive benefit from targeted therapies in this disease are still needed. Indeed, only RAS mutations have been identified as predictive of lack of benefit from monoclonal antibodies against EGFR in patients with mCRC. Panitumumab is a fully humanized monoclonal antibody against EGFR. In this study, we review data to support the use of panitumumab in combination with a chemotherapy backbone, in the first line setting in patients with RAS wild-type mCRC. Ongoing efforts are aimed at identifying smaller subsets of patients within the RAS wild-type group that will derive the largest benefit from anti-EGFR therapy. In the meantime, treatment with anti-EGFR therapy should be reserved for patients with RAS wild-type mCRC.

EGFR monoclonal antibodies in locally advanced head and neck squamous cell carcinoma: What is their current role?

Treatment options for locally advanced squamous cell carcinoma of the head and neck (SCCHN) include either surgical resection followed by radiation or chemoradiation, or definitive chemoradiation for which single-agent cisplatin is the best studied and established. The increasing understanding of the molecular biology of SCCHN has led to an interest in the development of targeted therapies. The epidermal growth factor receptor (EGFR) is over-expressed in nearly 80-90% of cases of SCCHN and correlates with poor prognosis and resistance to radiation. Preclinical evidence showed that blocking EGFR restores radiation sensitivity and enhances cytotoxicity. This finding led to clinical trials evaluating this class of agents and the approval of cetuximab in combination with radiation for the treatment of locally advanced SCCHN. This review is focused on the anti-EGFR monoclonal antibodies and their role either with radiotherapy or chemoradiation in unresectable LA SCCHN.

Randomized controlled trial on the skin toxicity of panitumumab in Japanese patients with metastatic colorectal cancer: HGCSG1001 study; J-STEPP

AIM

We planned a randomized, open-label trial to evaluate differences between pre-emptive and reactive skin treatment for panitumumab (Pmab)-associated skin toxicities in Japanese patients with metastatic colorectal cancer.

PATIENTS & METHODS

Patients receiving third-line Pmab-containing regimens were randomized to pre-emptive or reactive treatment. The primary end point was the cumulative incidence of ≥grade 2 skin toxicities during 6 weeks. Retrospectively, a dermatologist reviewed skin toxicities, in a blinded manner.

RESULTS

A total of 95 patients were enrolled (pre-emptive: 47, reactive: 48). The primary end point was achieved (21.3 and 62.5% [risk ratio: 0.34; p < 0.001], for pre-emptive and reactive treatment, respectively). A similar trend was observed in central review.

CONCLUSION

Pre-emptive skin treatment could reduce the severity of Pmab-associated skin toxicities in Japanese metastatic colorectal cancer patients.

Prospective noninterventional study on the use of panitumumab monotherapy in patients with recurrent or progressive colorectal cancer: the VECTIS study

Purpose

Epidermal growth factor receptor-targeted monoclonal antibodies are active as monotherapy beyond second-line treatment. Skin toxicities (STs) are common during treatment, and a positive association between ST severity and patient outcome has been reported. This study collected information on panitumumab monotherapy use in patients with KRAS exon 2 wild-type metastatic colorectal cancer in clinical practice.

Methods

This open-label, prospective, observational, noninterventional study included adult patients who had failed prior chemotherapy with 5-fluorouracil, oxaliplatin, and irinotecan. Patients received panitumumab monotherapy (6 mg/kg every 2 weeks) for ≤18 cycles. Effectiveness was assessed as disease control rate (DCR), tumor response, and freedom from progression. The incidence of ST and other adverse drug reactions (ADRs) was recorded, as were Eastern Cooperative Oncology Group performance status (ECOG PS) and quality of life. The KRAS analysis process was also evaluated.

Findings

The full analysis set included 632 patients (64.6% male; mean age, 62.3 years), who completed a mean of 9.6 panitumumab cycles. ST, mainly grade 1/2, occurred in 84.3% of patients, 82.7% of whom required treatment. Nonskin ADRs occurred in 3.5% of patients. By the end of treatment, the DCR was 58.9% overall, and was 53.8% and 62.7%, respectively in patients with ST grade 0/1 and grade 2/3. Significant associations were observed between maximum ST grade and best response (P=0.0009), DCR (P=0.0046), tumor response (P=0.0002), and freedom from progression (P=0.0084). At the end of the study, 67.4% of the patients had an ECOG PS of 0/1. Quality of life was rated as “very good” or “good” in 70.3% of patients. Mean time to obtain KRAS results was 18.2 days; satisfaction with different aspects of KRAS testing was “very good” or “good” in 80%–97% of patients.

Conclusion

Panitumumab monotherapy showed adequate effectiveness and safety in patients with heavily pretreated KRAS exon 2 wild-type metastatic colorectal cancer. The most common ADR was grade 1/2 ST.

Epidermal growth factor receptor-directed monoclonal antibodies in nonsmall cell lung cancer: an update

PURPOSE OF REVIEW

The epidermal growth factor receptor (EGFR) is overexpressed in many nonsmall cell lung cancers (NSCLCs). Blockade of EGFR by monoclonal antibodies has been studied as a strategy to improve the outcome of first-line chemotherapy in patients with NSCLC. The present review updates the findings from phase III trials.

RECENT FINDINGS

Cetuximab improved survival when combined with first-line chemotherapy and this benefit was limited to patients with high EGFR expression in their tumors. A Southwest Oncology Group study currently prospectively evaluates the predictive biomarkers for cetuximab. In the SQUIRE phase III trial, necitumumab added to cisplatin and gemcitabine increased the survival in patients with advanced squamous cell NSCLC. The INSPIRE trial studied chemotherapy with and without necitumumab in patients with nonsquamous NSCLC but was prematurely halted because of increased thromboembolic events with chemotherapy and necitumumab.

SUMMARY

EGFR monoclonal antibodies improved the outcome including survival in selected patients with advanced NSCLC. Prospective validation of predictive biomarkers is ongoing.

What is the best strategy for targeting EGF receptors in non-small-cell lung cancer?

EGF receptors (EGFRs) are often overexpressed or constitutively activated in non-small-cell lung cancer, and are an important therapeutic target. EGFR signaling can be blocked with tyrosine kinase inhibitors (TKIs) and anti-EGFR antibodies. Three EGFR-TKIs are approved as initial monotherapies in patients with EGFR-activating mutations, and erlotinib has a role as maintenance and second-line therapy. Investigational anti-EGFR monoclonal antibodies plus standard first-line therapy improve survival in patients with advanced non-small-cell lung cancer, especially in tumors with high EGFR expression. Anti-EGFR antibodies inhibit EGFR signaling and have the potential to stimulate antibody-dependent cell-mediated cytotoxicity. Multikinase TKIs are investigational as first- and second-line therapies, as monotherapies and in combination with chemotherapy. This article summarizes the available clinical data for EGFR-targeted therapies.

Emerging antibody-based therapeutic strategies for bladder cancer: A systematic review

Bladder cancer is the most common malignancy of the urinary tract, presents the highest recurrence rate among solid tumors and is the second leading cause of death in genitourinary cancers. Despite recent advances in understanding of pathophysiology of the disease, the management of bladder cancer patients remains a clinically challenging problem. Particularly, bladder tumors invading the muscularis propria and disseminated disease are often not responsive to currently available therapeutic approaches, which include surgery and conventional chemotherapy. Antibody-based therapeutic strategies have become an established treatment option for over a decade in several types of cancer. However, bladder cancer has remained mostly an "orphan disease" regarding the introduction of these novel therapeutics, which has been translated in few improvements in patients overall survival. In order to shift this paradigm, several clinical studies involving antibody-based therapeutic strategies targeting the most prominent bladder cancer-related biomolecular pathways and immunological mediators are ongoing. This systematic review explores antibody-based therapeutics for bladder cancer undergoing clinical trial and discusses the future perspectives in this field, envisaging the development of more effective guided therapeutics.

Label-Free Raman Spectroscopic Imaging Monitors the Integral Physiologically Relevant Drug Responses in Cancer Cells

Predictions about the cellular efficacy of drugs tested in vitro are usually based on the measured responses of a few proteins or signal transduction pathways. However, cellular proteins are highly coupled in networks, and observations of single proteins may not adequately reflect the in vivo cellular response to drugs. This might explain some large discrepancies between in vitro drug studies and drug responses observed in patients. We present a novel in vitro marker-free approach that enables detection of cellular responses to a drug. We use Raman spectral imaging to measure the effect of the epidermal growth factor receptor (EGFR) inhibitor panitumumab on cell lines expressing wild-type Kirsten-Ras (K-Ras) and oncogenic K-Ras mutations. Oncogenic K-Ras mutation blocks the response to anti-EGFR therapy in patients, but this effect is not readily observed in vitro. The Raman studies detect large panitumumab-induced differences in vitro in cells harboring wild-type K-Ras as seen in A in red but not in cells with K-Ras mutations as seen in B; these studies reflect the observed patient outcomes. However, the effect is not observed when extracellular-signal-regulated kinase phosphorylation is monitored. The Raman spectra show for cells with wild-type K-Ras alterations based on the responses to panitumumab. The subcellular component with the largest spectral response to panitumumab was lipid droplets, but this effect was not observed when cells harbored K-Ras mutations. This study develops a noninvasive, label-free, in vitro vibrational spectroscopic test to determine the integral physiologically relevant drug response in cell lines. This approach opens a new field of patient-centered drug testing that could deliver superior patient therapies.

Gastric cancer and the epoch of immunotherapy approaches

The incidence of gastric cancer (GC) fell dramatically over the last 50 years, but according to IARC-Globocan 2008, it is the third most frequent cause of cancer-related deaths with a case fatality GC ratio higher than other common malignancies. Surgical resection is the primary curative treatment for GC though the overall 5-year survival rate remains poor (approximately 20%-25%). To improve the outcome of resectable gastric cancer, different treatment strategies have been evaluated such as adjuvant or perioperative chemotherapy. In resected gastric cancer, the addition of radiotherapy to chemotherapy does not appear to provide any additional benefit. Moreover, in metastatic patients, chemotherapy is the mainstay of palliative therapy with a median overall survival of 8-10 mo and objective response rates of merely 20%-40%. Therefore, the potential for making key beneficial progress is to investigate the GC molecular biology to realize innovative therapeutic strategies, such as specific immunotherapy. In this review, we provide a panoramic view of the different immune-based strategies used for gastric cancer treatment and the results obtained in the most significant clinical trials. In detail, firstly we describe the therapeutic approaches that utilize the monoclonal antibodies while in the second part we analyze the cell-based immunotherapies.

EGFR-directed monoclonal antibodies in non-small cell lung cancer: how to predict efficacy?

Cetuximab improved survival when added to first-line platinum-based chemotherapy in patients with advanced non-small cell lung cancer. In order to determine those patients who will derive the greatest benefit from the addition of cetuximab, the associations of clinical and tumor features with clinical outcome were determined. High EGFR expression of tumor cells based on an immunohistochemistry score was shown to predict benefit of cetuximab. Among patients with high EGFR expression, the hazard ratio for death was 0.73 in favor of chemotherapy plus cetuximab compared to chemotherapy alone. Among patients with low EGFR expression, no difference in survival was observed between patients treated with chemotherapy plus cetuximab compared to those treated with chemotherapy alone. The treatment interaction test was significant. KRAS mutation status and EGFR copy numbers were without predictive value. Patients with EGFR-activating mutations in their tumors had longer survival independent of the use of cetuximab. In conclusion, EGFR expression levels lend themselves as predictive biomarkers for the selection of those patients who will benefit from the addition of cetuximab to first-line chemotherapy with platinum-based doublets.

Immune biomarkers of anti-EGFR monoclonal antibody therapy

The tumor antigen (TA)-targeted monoclonal antibodies (mAb) cetuximab and panitumumab target the human epidermal growth factor receptor and have been integrated into treatment regimens for advanced squamous cell carcinoma of the head and neck (SCCHN). The therapeutic efficacy of these mAbs has been found to be enhanced when combined with radiotherapy and chemotherapy. However, clinical trials indicate that these findings are limited to fewer than 20% of treated patients. Therefore, identifying patients who are likely to benefit from these agents is crucial to improving therapeutic strategies. Interestingly, it has been noted that TA-targeted mAbs mediate their effects by contributing to cell-mediated cytotoxicity in addition to inhibition of downstream signaling pathways. Here, we describe the potential immunogenic mechanisms underlying these clinical findings, their role in the varied clinical response and identify the putative biomarkers of antitumor activity. We review potential immunological biomarkers that affect mAb therapy in SCCHN patients, the implications of these findings and how they translate to the clinical scenario, which are critical to improving patient selection and ultimately outcomes for patients undergoing therapy.

MicroPET/CT imaging of patient-derived pancreatic cancer xenografts implanted subcutaneously or orthotopically in NOD-scid mice using (64)Cu-NOTA-panitumumab F(ab')2 fragments

INTRODUCTION

Our objective was to study microPET/CT imaging of patient-derived pancreatic cancer xenografts in NOD-scid mice using F(ab')2 fragments of the fully-human anti-EGFR monoclonal antibody, panitumumab (Vectibix) labeled with (64)Cu. More than 90% of pancreatic cancers are EGFR-positive.

METHODS

F(ab')2 fragments were produced by proteolytic digestion of panitumumab IgG or non-specific human IgG, purified by ultrafiltration then modified with NOTA chelators for complexing (64)Cu. Panitumumab IgG and Fab fragments were similarly labeled with (64)Cu. EGFR immunoreactivity was determined in competition and direct (saturation) cell binding assays. The biodistribution of (64)Cu-labeled panitumumab IgG, F(ab')2 and Fab was compared in non-tumor-bearing Balb/c mice. MicroPET/CT and biodistribution studies were performed in NOD-scid mice engrafted subcutaneously (s.c.) or orthotopically with patient-derived OCIP23 pancreatic tumors, or in NOD-scid with s.c. PANC-1 human pancreatic cancer xenografts.

RESULTS

Panitumumab F(ab')2 fragments were produced in high purity (>90%), derivitized with 3.2±0.7 NOTA/F(ab')2, and labeled with (64)Cu (0.3-3.6MBq/μg). The binding of (64)Cu-NOTA-panitumumab F(ab')2 to OCIP23 or PANC-1 cells was decreased significantly by an excess of panitumumab IgG. The Kd for binding of (64)Cu-NOTA-panitumumab F(ab')2 to EGFR on PANC-1 cells was 0.14±0.05nmol/L. F(ab')2 fragments exhibited more suitable normal tissue distribution for tumor imaging with (64)Cu than panitumumab IgG or Fab. Tumor uptake at 48h post injection (p.i.) of (64)Cu-NOTA-panitumumab F(ab')2 was 12.0±0.9% injected dose/g (ID/g) in s.c. and 11.8±0.9% ID/g in orthotopic OCIP23 tumors vs. 6.1±1.1% ID/g in s.c. PANC-1 xenografts. Tumor/Blood (T/B) ratios were 5:1 to 9:1 for OCIP23 and 2.4:1 for PANC-1 tumors. Tumor uptake of (64)Cu-NOTA-non-specific F(ab')2 in OCIP23 xenografts was 5-fold lower than (64)Cu-panitumumab F(ab')2. All tumor xenografts were clearly imaged by microPET/CT at 24 or 48h p.i. of (64)Cu-NOTA-panitumumab F(ab')2.

CONCLUSIONS

(64)Cu-panitumumab F(ab')2 fragments bound with high affinity to EGFR on pancreatic cancer cells in vitro and localized specifically in patient-derived pancreatic cancer xenografts in mice in vivo, allowing tumor visualization by microPET/CT at 24 or 48h p.i.

Novel drugs against non-small-cell lung cancer

PURPOSE OF REVIEW

Important therapeutic advances for patients with advanced non-small-cell lung cancer (NSCLC) with focus on individualized therapy have recently occurred and are summarized in this review.

RECENT FINDINGS

Cetuximab added to first-line chemotherapy has been shown to improve survival in patients with high epidermal growth factor receptor (EGFR) expression in their tumors. Afatinib has shown improved progression-free survival and better quality of life compared to chemotherapy in patients with EGFR-mutation-positive adenocarcinomas. Several other EGFR-directed agents are in clinical development. Crizotinib improved progression-free survival compared to second-line chemotherapy with docetaxel or pemetrexed in patients with advanced anaplastic lymphoma kinase-positive NSCLC. Selumetinib added to docetaxel has improved outcome compared with docetaxel in a randomized phase II trial in patients with advanced KRAS-mutant NSCLC and this combination is currently studied in a phase III trial. Nintedanib added to docetaxel improved progression-free survival in the second-line therapy of patients with advanced NSCLC but many other angiogenesis inhibitors failed to improve clinical outcome in phase III trials. Several other targeted therapies are currently evaluated in phase III trials in patients with advanced NSCLC.

SUMMARY

Recent trials have led to the approval of afatinib and crizotinib for subsets of patients with advanced NSCLC.

Gene therapy for cancer: present status and future perspective

Advancements in human genomics over the last two decades have shown that cancer is mediated by somatic aberration in the host genome. This discovery has incited enthusiasm among cancer researchers; many now use therapeutic approaches in genetic manipulation to improve cancer regression and find a potential cure for the disease. Such gene therapy includes transferring genetic material into a host cell through viral (or bacterial) and non-viral vectors, immunomodulation of tumor cells or the host immune system, and manipulation of the tumor microenvironment, to reduce tumor vasculature or to increase tumor antigenicity for better recognition by the host immune system. Overall, modest success has been achieved with relatively minimal side effects. Previous approaches to cancer treatment, such as retrovirus integration into the host genome with the risk of mutagenesis and second malignancies, immunogenicity against the virus and/or tumor, and resistance to treatment with disease relapse, have markedly decreased with the new generation of viral and non-viral vectors. Several tumor-specific antibodies and genetically modified immune cells and vaccines have been developed, yet few are presently commercially available, while many others are still ongoing in clinical trials. It is anticipated that gene therapy will play an important role in future cancer therapy as part of a multimodality treatment, in combination with, or following other forms of cancer therapy, such as surgery, radiation and chemotherapy. The type and mode of gene therapy will be determined based on an individual's genomic constituents, as well as his or her tumor specifics, genetics, and host immune status, to design a multimodality treatment that is unique to each individual's specific needs.

Gene therapy for cancer: present status and future perspective

Advancements in human genomics over the last two decades have shown that cancer is mediated by somatic aberration in the host genome. This discovery has incited enthusiasm among cancer researchers; many now use therapeutic approaches in genetic manipulation to improve cancer regression and find a potential cure for the disease. Such gene therapy includes transferring genetic material into a host cell through viral (or bacterial) and non-viral vectors, immunomodulation of tumor cells or the host immune system, and manipulation of the tumor microenvironment, to reduce tumor vasculature or to increase tumor antigenicity for better recognition by the host immune system. Overall, modest success has been achieved with relatively minimal side effects. Previous approaches to cancer treatment, such as retrovirus integration into the host genome with the risk of mutagenesis and second malignancies, immunogenicity against the virus and/or tumor, and resistance to treatment with disease relapse, have markedly decreased with the new generation of viral and non-viral vectors. Several tumor-specific antibodies and genetically modified immune cells and vaccines have been developed, yet few are presently commercially available, while many others are still ongoing in clinical trials. It is anticipated that gene therapy will play an important role in future cancer therapy as part of a multimodality treatment, in combination with, or following other forms of cancer therapy, such as surgery, radiation and chemotherapy. The type and mode of gene therapy will be determined based on an individual's genomic constituents, as well as his or her tumor specifics, genetics, and host immune status, to design a multimodality treatment that is unique to each individual's specific needs.

Review on targeted treatment of patients with advanced-stage renal cell carcinoma: a medical oncologist's perspective

Renal cell carcinomas make up 3% of all cancers and one in four patients is metastatic at time of diagnosis. This cancer is one of the most resistant to cytotoxic chemotherapy. Studies have shown that the efficiency of interferon-alpha and/or interleukin-2 based immune therapies is limited in patients with metastatic renal cell carcinoma but latest advances in molecular biology and genetic science have resulted in better understanding of its biology. Tumor angiogenesis, tumor proliferation and metastasis develop by the activation of signal message pathways playing a role in the development of renal cell carcinomas. Better definition of these pathways has caused an increase in preclinic and clinical studies into target directed treatment of renal cell carcinoma. Many recent studies have shown that numerous anti-angiogenic agents have marked clinical activity. In this article, the focus is on general characteristics of molecular pathways playing a major role in renal cell carcinoma, reviewing clinical information onagents used in the target directed treatment of metastatic lesions.

FcγRIIa and FcγRIIIa polymorphisms and cetuximab benefit in the microscopic disease

PURPOSE

FcγR polymorphisms have been reported to enhance the immune-mediated effects of cetuximab in metastatic colorectal cancer. There are no data on the relationship between these polymorphisms and cetuximab in the early-stage setting. We performed a pharmacogenomic analysis of EXPERT-C, a randomized phase II trial of neoadjuvant CAPOX followed by chemoradiotherapy, surgery, and adjuvant CAPOX±cetuximab in high-risk, locally advanced rectal cancer.

EXPERIMENTAL DESIGN

FcγRIIa-H131R and FcγRIIIa-V158F polymorphisms were analyzed on DNA from peripheral blood samples. Kaplan-Meier method and Cox regression analysis were used to calculate survival estimates and compare treatment arms.

RESULTS

Genotyping was successfully performed in 105 of 164 (64%) patients (CAPOX=54, CAPOX-C=51). No deviation from the Hardy-Weinberg equilibrium or association of these polymorphisms with tumor RAS status was observed. FcγRIIa-131R (HR, 0.38; P=0.058) and FcγRIIIa-158F alleles (HR, 0.21; P=0.007) predicted improved progression-free survival (PFS) in patients treated with cetuximab. In the CAPOX-C arm, carriers of both 131R and 158F alleles had a statistically significant improvement in PFS (5 years: 78.4%; HR, 0.22; P=0.002) and overall survival (OS; 5 years: 86.4%; HR, 0.24; P=0.018) when compared with patients homozygous for 131H and/or 158V (5-year PFS: 35.7%; 5-year OS: 57.1%). An interaction between cetuximab benefit and 131R and 158F alleles was found for PFS (P=0.017) and remained significant after adjusting for prognostic variables (P=0.003).

CONCLUSION

This is the first study investigating FcγRIIa and FcγRIIIa polymorphisms in patients with early-stage colorectal cancer treated with cetuximab. We showed an increased clinical benefit from cetuximab in the presence of 131R and 158F alleles.

Antibodies directed against receptor tyrosine kinases: current and future strategies to fight cancer

Approximately 30 therapeutic monoclonal antibodies have already been approved for cancers and inflammatory diseases, and monoclonal antibodies continue to be one of the fastest growing classes of therapeutic molecules. Because aberrant signaling by receptor tyrosine kinases (RTKs) is a commonly observed factor in cancer, most of the subclasses of RTKs are being extensively studied as potential targets for treating malignancies. The first two RTKs that have been targeted by antibody therapy, with five currently marketed antibodies, are the growth factor receptors EGFR and HER2. However, due to systemic side effects, refractory patients and the development of drug resistance, these treatments are being challenged by emerging therapeutics. This review examines current monoclonal antibody therapies against RTKs. After an analysis of agents that have already been approved, we present an analysis of antibodies in clinical development that target RTKs. Finally, we highlight promising RTKs that are emerging as new oncological targets for antibody-based therapy.

RAS mutations and cetuximab in locally advanced rectal cancer: results of the EXPERT-C trial

BACKGROUND

RAS mutations predict resistance to anti-epidermal growthfactor receptor (EGFR) monoclonal antibodies in metastatic colorectal cancer. We analysed RAS mutations in 30 non-metastatic rectal cancer patients treated with or without cetuximab within the 31 EXPERT-C trial.

METHODS

Ninety of 149 patients with tumours available for analysis were KRAS/BRAF wild-type, and randomly assigned to capecitabine plus oxaliplatin (CAPOX) followed by chemoradiotherapy, surgery and adjuvant CAPOX or the same regimen plus cetuximab (CAPOX-C). Of these, four had a mutation of NRAS exon 3, and 84 were retrospectively analysed for additional KRAS (exon 4) and NRAS (exons 2/4) mutations by using bi-directional Sanger sequencing. The effect of cetuximab on study end-points in the RAS wild-type population was analysed.

RESULTS

Eleven (13%) of 84 patients initially classified as KRAS/BRAF wild-type were found to have a mutation in KRAS exon 4 (11%) or NRAS exons 2/4 (2%). Overall, 78/149 (52%) assessable patients were RAS wild-type (CAPOX, n=40; CAPOX-C, n=38). In this population, after a median follow-up of 63.8months, in line with the initial analysis, the addition of cetuximab was associated with numerically higher, but not statistically significant, rates of complete response (15.8% versus 7.5%, p=0.31), 5-year progression-free survival (75.5% versus 67.5%, hazard ratio (HR) 0.61, p=0.25) and 5-year overall survival (83.8% versus 70%, HR 0.54, p=0.20).

CONCLUSIONS

RAS mutations beyond KRAS exon 2 and 3 were identified in 17% of locally advanced rectal cancer patients. Given the small sample size, no definitive conclusions on the effect of additional RAS mutations on cetuximab treatment in this setting can be drawn and further investigation of RAS in larger studies is warranted.

Panitumumab in colorectal cancer

The combination of chemotherapy and targeted therapies is rapidly becoming the standard of care in the treatment of metastatic colorectal cancer. Panitumumab (formerly ABX-EGF) is a fully human antibody developed to target the human epidermal growth factor receptor (EGFR/HER-1), which is expressed in up to 75% of patients with colorectal cancer. As a fully human antibody, panitumumab can be administered without any premedication and few infusion reactions have been reported. It has recently been approved in the USA for the treatment of colorectal cancer as a single agent in the salvage setting. Ongoing studies are being performed to determine whether the addition of panitumumab to standard treatment for metastatic colorectal cancer will improve the survival of these patients.

Improving therapeutic ratio in head and neck cancer with adjuvant and cisplatin-based treatments

Advanced head and neck cancers are difficult to manage despite the large treatment arsenal currently available. The multidisciplinary effort to increase disease-free survival and diminish normal tissue toxicity was rewarded with better locoregional control and sometimes fewer side effects. Nevertheless, locoregional recurrence is still one of the main reasons for treatment failure. Today, the standard of care in head and neck cancer management is represented by altered fractionation radiotherapy combined with platinum-based chemotherapy. Targeted therapies as well as chronotherapy were trialled with more or less success. The aim of the current work is to review the available techniques, which could contribute towards a higher therapeutic ratio in the treatment of advanced head and neck cancer patients.

Anti-angiogenic therapies for metastatic colorectal cancer: Current and future perspectives

Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer and the second leading cause of cancer death in both men and women in the United States, with about 142820 new cases and 50830 deaths expected in 2013. Metastatic disease (mCRC) remains a challenge for oncologists worldwide due to its potential comorbidities. Recently, chemotherapy regimens containing 5-fluorouracil, leucovorin, oxaliplatin and irinotecan combinations are a standard of care in the metastatic disease. Currently, biological therapies involving vascular endothelial growth factor and epidermal growth factor receptor pathways, such as bevacizumab and cetuximab, have emerged as good option for improving mCRC patient survival. Now, aflibercept plus standard chemotherapy has also been approved in second line regimen for mCRC patients. Our review will discuss novel biological drugs and their indications for mCRC patients and will bring future perspectives in this regard.

Gene expression profiles can predict panitumumab monotherapy responsiveness in human tumor xenograft models

BACKGROUND

Epidermal growth factor receptor (EGFR)-targeted agents have demonstrated clinical benefit in patients with cancer. Identifying tissue-of-origin-independent predictive biomarkers is important to optimally treat patients. We sought to identify a gene array profile that could predict responsiveness to panitumumab, a fully human EGFR-binding antibody, using preclinical models of human cancer.

METHODS

Mice bearing 25 different xenograft models were treated twice weekly with panitumumab or immunoglobulin G2 control to determine their responsiveness to panitumumab. Samples from these xenografts and untreated xenografts were arrayed on the Affymetrix human U133A gene chip to identify gene sets predicting responsiveness to panitumumab using univariate and multivariate analyses. The predictive models were validated using the leave-one-group-out (LOO) method.

RESULTS

Of the 25 xenograft models tested, 12 were responsive and 13 were resistant to panitumumab. Unsupervised analysis demonstrated that the xenograft models clustered by tissue type rather than responsiveness to panitumumab. After normalizing for tissue effects, samples clustered by responsiveness using an unsupervised multidimensional scaling. A multivariate selection algorithm was used to select 13 genes that could stratify xenograft models based on responsiveness after adjustment for tissue effects. The method was validated using the LOO method on a training set of 22 models and confirmed independently on three new models. In contrast, a univariate gene selection method resulted in higher misclassification rates.

CONCLUSION

A model was constructed from microarray data that prospectively predict responsiveness to panitumumab in xenograft models. This approach may help identify patients, independent of disease origin, likely to benefit from panitumumab.

Promising new molecular targeted therapies in head and neck cancer

Despite advances in multimodality therapies for the treatment of squamous cell carcinoma of the head and neck (SCCHN), survival rates, functional outcomes and toxicities of therapy remain poor. The recognition of the prognostic value of human papillomavirus (HPV) status, and the advent of biologically targeted therapies with potential for decreased toxicities and increased selectivity, represent significant developments in our understanding of SCCHN. Targeted agents currently approved or under investigation for SCCHN include epidermal growth factor receptor (EGFR) monoclonal antibodies (cetuximab, panitumumab, zalutumumab, nimotuzumab), EGFR tyrosine kinase inhibitors (gefitinib, erlotinib, lapatinib, afatanib, dacomitinib), vascular endothelial growth factor receptor (VEGFR) inhibitors (bevacizumab, sorafenib, sunitinib, vandetanib) and various inhibitors of other pathways and targets, including phosphatidylinositol 3' kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR), MET and insulin-like growth factor receptor (IGF-1R). On-going clinical trials are evaluating these emerging agents and their combinations in the treatment of SCCHN.

Personalizing colon cancer therapeutics: targeting old and new mechanisms of action

The use of pharmaceuticals for colon cancer treatment has been increasingly personalized, in part due to the development of new molecular tools. In this review, we discuss the old and new colon cancer chemotherapeutics, and the parameters that have been shown to be predictive of efficacy and safety of these chemotherapeutics. In addition, we discuss how alternate pharmaceuticals have been developed in light of a potential lack of response or resistance to a particular chemotherapeutic.

Epidermal growth factor receptor targeting in cancer: a review of trends and strategies

The epidermal growth factor receptor (EGFR) is a cell-surface receptor belonging to ErbB family of tyrosine kinase and it plays a vital role in the regulation of cell proliferation, survival and differentiation. However; EGFR is aberrantly activated by various mechanisms like receptor overexpression, mutation, ligand-dependent receptor dimerization, ligand-independent activation and is associated with development of variety of tumors. Therefore, specific EGFR inhibition is one of the key targets for cancer therapy. Two major approaches have been developed and demonstrated benefits in clinical trials for targeting EGFR; monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs). EGFR inhibitors like, cetuximab, panitumumab, etc. (mAbs) and gefitinib, erlotinib, lapatinib, etc. (TKIs) are now commercially available for treatment of variety of cancers. Recently, many other agents like peptides, nanobodies, affibodies and antisense oligonucleotide have also shown better efficacy in targeting and inhibiting EGFR. Now a days, efforts are being focused to identify molecular markers that can predict patients more likely to respond to anti-EGFR therapy; to find out combinatorial approaches with EGFR inhibitors and to bring new therapeutic agents with clinical efficacy. In this review we have outlined the role of EGFR in cancer, different types of EGFR inhibitors, preclinical and clinical status of EGFR inhibitors as well as summarized the recent efforts made in the field of molecular EGFR targeting.

Panitumumab in combination with infusional oxaliplatin and oral capecitabine for conversion therapy in patients with colon cancer and advanced liver metastases. The MetaPan study

BACKGROUND

Preoperative chemotherapy improves the outcome in patients with colorectal cancer with liver metastases. In the current study, the authors evaluated the activity of a conversion treatment with the combination of capecitabine plus oxaliplatin (XELOX) used in association with panitumumab in patients with unresectable, liver-only, metastatic colon cancer.

METHODS

Chemotherapy-naive patients with unresectable liver metastases from colon cancer with no other metastatic disease sites were enrolled. All patients received upfront therapy with XELOX plus panitumumab (P-XELOX) and were reevaluated for resectability every 4 cycles. The primary endpoint was the objective response rate (ORR). Secondary endpoints were overall survival (OS), progression-free survival, the percentage of patients whose disease became radically resectable, and the safety of the P-XELOX combination.

RESULTS

A total of 49 patients were recruited, 35 of whom had wild-type KRAS (wtKRAS) and 14 of whom (who were enrolled before study amendment) had unknown (9 patients) or mutated (5 patients) KRAS mutational status. Forty-six patients were evaluable for response. After conversion P-XELOX therapy, the ORR in the general population was 54%, with 2 complete responses, 23 partial responses, and 14 cases of stable disease. In patients with wtKRAS, the ORR of the patients reached 65% (2 CRs and 19 PRs), which allowed 15 patients with initial unresectable liver metastasis to be reclassified as having resectable disease. Survival analysis demonstrated a median progression-free survival of 8.5 months and a median OS of 21.9 months. Patients who underwent surgery were found to have a significantly better OS when compared with those who did not undergo surgery (P < .001). Overall, toxicities were found to be predictable and manageable, with the most common being cutaneous, gastrointestinal, and neurologic toxicities.

CONCLUSIONS

Conversion P-XELOX therapy yields high response and resectability rates for patients with metastatic colon cancer with extensive liver involvement.

A real-life experience using panitumumab in chemo-refractory metastatic colorectal cancer patients: a retrospective analysis at the Jewish General Hospital, 2009-2012

BACKGROUND

Panitumumab is a fully human monoclonal antibody, directed against the epidermal growth factor receptor, that was shown to be effective in third-line metastatic colorectal cancer. We performed a retrospective analysis of patients with chemo-refractory non-KRAS-mutated metastatic colorectal cancer, who received panitumumab at the Jewish General Hospital in Montreal, Canada, between 2009 and 2012.

METHODS

This chart review included 44 patients (median age: 60 years; performance status: 0-3), of whom 50% had already received three lines of treatment. The primary endpoint was progression-free survival (pfs). Secondary endpoints were overall survival and safety. Tumour progression was determined by radiologic assessments performed once every 3 months per clinical guidelines or by clinical deterioration as determined by the clinician-investigator.

RESULTS

In our sample, median pfs was 21.86 ± 5.23 weeks (95% confidence interval: 12.9 to 36.9 weeks) and overall survival was 35.14 ± 7.75 weeks (95% confidence interval: 25.6 to 73.4 weeks) with a median of 5 cycles of panitumumab treatment. The most frequently reported toxicities with panitumumab were skin toxicity (16.2% grade 3) and hypomagnesemia (10.8% grade 3). No infusion reactions were reported.

CONCLUSIONS

Despite a small sample size from a single institution, our survival and efficacy data are encouraging and comparable to results obtained from the registration panitumumab trial. Our findings suggest that panitumumab can be effective and tolerable in a real-world setting.