Panitumumab: a summary of clinical development in colorectal cancer and future directions

Clinical and Translational Research Challenges in Biliary Tract Cancers

BACKGROUND

Biliary Tract Cancers (BTC) are rare malignancies with a poor prognosis. There are many challenges encountered in treating these patients in daily practice as well as in clinical, translational and basic research.

OBJECTIVE

This review summarises the most relevant challenges in clinical and translational research in BTCs and suggests potential solutions towards an improvement in quality of life and outcomes of patients diagnosed with such malignancies.

FINDINGS

The main challenge is the low number of patients with BTCs, complicated by the aggressive natural behaviour of cancer and the lack of funding sources for research. In addition, the clinical characteristics of these patients and the specific cancer-related complications challenge clinical research and clinical trial recruitment. It is worth highlighting that BTCs are a group of different malignancies (cholangiocarcinoma, gallbladder cancer and ampullary cancer) rather than a unique homogeneous disease. These subgroups differ not only in molecular aspects, but also in clinical and demographic characteristics. In addition, tailored imaging and quality of life assessment are required to tackle some of the issues specific to BTCs. Finally, difficulties in tissue acquisition both in terms of biopsy size and inclusion of sufficient tumour within the samples, may adversely impact translational and basic research.

CONCLUSION

Increasing awareness among patients and clinicians regarding BTC and the need for further research and treatment development may address some of the main challenges in BTC research. International collaboration is mandatory to progress the field.

Prospective Observational Cohort Study to Describe the Use of Panitumumab in Combination with Chemotherapy in Real-World Clinical Practice for Patients with Wild-Type RAS mCRC

INTRODUCTION

This study aimed to better understand panitumumab use in real-life clinical practice in first- and second-line treatment of metastatic colorectal cancer in five European countries.

METHODS

This is a combined analysis of two observational, non-interventional prospective cohort studies, one of which was conducted in Germany and France, the other in Bulgaria, Czech Republic, and Hungary. The studies observed patients with wild-type [Kirsten] rat sarcoma viral oncogene homolog ([K]RAS/RAS) metastatic colorectal cancer (mCRC), who had been treated with panitumumab in combination with fluorouracil, leucovorin, and oxaliplatin (FOLFOX) in the first line or with panitumumab combined with fluorouracil, leucovorin, and irinotecan (FOLFIRI) in the second line following fluoropyrimidine-based chemotherapy. The planned duration of observation was 12 months from the first dose of panitumumab.

RESULTS

A total of 332 patients treated with panitumumab + FOLFOX in the first line and 94 patients treated with panitumumab + FOLFIRI in the second line were analyzed. The median number of panitumumab infusions was 10.0 in first-line FOLFOX patients and 11.5 in second-line FOLFIRI patients; the median duration of panitumumab exposure was 5.7 and 6.9 months, respectively. The unadjusted overall response rate (complete or partial response) in patients with available post-baseline response assessment (n = 290) was 51.7% in first-line FOLFOX and 44.9% in second-line FOLFIRI patients. In the first-line setting, resectability was achieved in 9.3%. Reported hospitalizations were mostly cancer-related visits such as scheduled anticancer treatment administrations, tumor assessment visits, or interventions. The majority of adverse drug reactions were skin disorders, with 75.3% in first-line FOLFOX patients and 72.3% in second-line FOLFIRI patients.

CONCLUSION

Overall, the study results show that treatment patterns, clinical efficacy, and the safety profile of panitumumab in routine clinical practice were comparable to those in randomized controlled trials. The relatively low skin toxicity rate could be attributed to increasing experience in managing panitumumab-associated rash and some degree of underreporting.

FUNDING

Amgen.

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.

Cancer-related CD15/FUT4 overexpression decreases benefit to agents targeting EGFR or VEGF acting as a novel RAF-MEK-ERK kinase downstream regulator in metastatic colorectal cancer

BACKGROUND

Cancer-related immune antigens in the tumor microenvironment could represent an obstacle to agents targeting EGFR "cetuximab" or VEGF "bevacizumab" in metastatic colorectal cancer (mCRC) patients.

METHODS

Infiltrating immune cells into tumor tissues, cancer-related expression of immune antigens (CD3, CD8, CD68, CD73, MPO, CD15/FUT4) from 102 mCRC patients receiving first-line Cetuximab or Bevacizumab plus chemotherapy were assessed by immunohistochemistry and validated in an independent tissue microarrays of 140 patients. Genome-wide expression profiles from 436 patients and 60 colon cancer cell lines were investigated using bioinformatics analysis. In vitro kinase assays of target genes activated by chemokines or growth factors were performed.

RESULTS

Here, we report that cancer-related CD15/FUT4 is overexpressed in most of mCRCs patients (43 %) and associates with lower intratumoral CD3+ and CD8+ T cells, higher systemic inflammation (NLR at diagnosis >5) and poorer outcomes, in terms of response and progression-free survival than those CD15/FUT4-low or negative ones (adjusted hazard ratio (HR) = 2.92; 95 % CI = 1.86-4.41; P < 0.001). Overexpression of CD15/FUT4 is induced through RAF-MEK-ERK kinase cascade, suppressed by MEK inhibitors and exhibits a close connection with constitutive oncogenic signalling pathways that respond to ERBB3 or FGFR4 activation (P < 0.001). CD15/FUT4-high expressing colon cancer cells with primary resistance to cetuximab or bevacizumab are significantly more sensitive to MEK inhibitors than CD15/FUT4-low counterparts.

CONCLUSION

Cancer-related CD15/FUT4 overexpression participates in cetuximab or bevacizumab mechanisms of resistance in mCRC patients. CD15/FUT4 as a potential target of the antitumor immune response requires further evaluation in clinical studies.

A Phase II Study of Sorafenib Combined With Cetuximab in EGFR-Expressing, KRAS-Mutated Metastatic Colorectal Cancer

BACKGROUND

Mutations in the KRAS gene predict for resistance to anti-epidermal growth factor receptor (EGFR) therapies, including cetuximab. Upregulation of vascular endothelial growth factor (VEGF)-A has been implicated in resistance to anti-EGFR treatment. Abrogation of the VEGF and RAS/RAF/MEK/ERK pathways has the potential to restore cetuximab sensitivity.

PATIENTS AND METHODS

Adult patients with histologically documented, measurable, EGFR-expressing, KRAS-mutated metastatic colorectal cancer (mCRC) that had progressed after 5-fluorouracil-based regimens were treated with sorafenib 400 mg orally twice daily and intravenous cetuximab weekly in 28-day cycles. The primary endpoint was the response rate (complete response, partial response, and stable disease at 4 cycles). The secondary endpoints included plasma biomarker analysis of angiogenic cytokines and correlative imaging studies with dynamic contrast-enhanced magnetic resonance imaging and zirconium 89-panitumumab.

RESULTS

Of the 30 patients enrolled, 26 were evaluable for response. Of the 26 patients evaluated, 4 had stable disease at 4 cycles and 1 had stable disease at 8 cycles. The median progression-free survival was 1.84 months. The common toxicities were rash, diarrhea, and liver enzyme elevations. Of the angiogenic cytokines evaluated, only the placental growth factor increased significantly with treatment (P < .0001). No pharmacodynamic parameters were associated with the treatment response.

CONCLUSION

We report the results of a trial that combined cetuximab and sorafenib for the treatment of KRAS-mutated mCRC, with correlative imaging studies and pharmacodynamic angiogenic cytokine profiling as downstream markers of EGFR and VEGF receptor (VEGFR) signaling. No objective responses were observed. Additional development of biomarkers for patient selection is needed to evaluate combined EGFR and VEGFR blockade as a therapeutic option in KRAS-mutated CRC.

Enhanced Targeting of the EGFR Network with MM-151, an Oligoclonal Anti-EGFR Antibody Therapeutic

Although EGFR is a validated therapeutic target across multiple cancer indications, the often modest clinical responses to current anti-EGFR agents suggest the need for improved therapeutics. Here, we demonstrate that signal amplification driven by high-affinity EGFR ligands limits the capacity of monoclonal anti-EGFR antibodies to block pathway signaling and cell proliferation and that these ligands are commonly coexpressed with low-affinity EGFR ligands in epithelial tumors. To develop an improved antibody therapeutic capable of overcoming high-affinity ligand-mediated signal amplification, we used a network biology approach comprised of signaling studies and computational modeling of receptor-antagonist interactions. Model simulations suggested that an oligoclonal antibody combination may overcome signal amplification within the EGFR:ERK pathway driven by all EGFR ligands. Based on this, we designed MM-151, a combination of three fully human IgG1 monoclonal antibodies that can simultaneously engage distinct, nonoverlapping epitopes on EGFR with subnanomolar affinities. In signaling studies, MM-151 antagonized high-affinity EGFR ligands more effectively than cetuximab, leading to an approximately 65-fold greater decrease in signal amplification to ERK. In cell viability studies, MM-151 demonstrated antiproliferative activity against high-affinity EGFR ligands, either singly or in combination, while cetuximab activity was largely abrogated under these conditions. We confirmed this finding both in vitro and in vivo in a cell line model of autocrine high-affinity ligand expression. Together, these preclinical studies provide rationale for the clinical study of MM-151 and suggest that high-affinity EGFR ligand expression may be a predictive response marker that distinguishes MM-151 from other anti-EGFR therapeutics.

Design and evaluation of radiolabeled tracers for tumor imaging

The growing understanding of tumor biology and the identification of tumor-specific genetic and molecular alterations, such as the overexpression of membrane receptors and other proteins, allows for personalization of patient management using targeted therapies. However, this puts stringent demands on the diagnostic tools used to identify patients who are likely to respond to a particular treatment. Radionuclide molecular imaging is a promising noninvasive method to visualize and characterize the expression of such targets. A number of different proteins, from full-length antibodies and their derivatives to small scaffold proteins and peptide receptor-ligands, have been applied to molecular imaging, each demonstrating strengths and weaknesses. Here, we discuss the concept of molecular targeting and, in particular, molecular imaging of cancer-associated targets. Additionally, we describe important biotechnological considerations and desired features when designing and developing tracers for radionuclide molecular imaging.

Orofacial adverse effects of biological agents

Biological agents (BA) are increasingly used effectively in the treatment of a range of disorders, but to date, their application in diseases affecting the orofacial region has been fairly limited. Several orofacial adverse effects related to BA have been recently reported. However, the evidence for such adverse reactions is not always strong, and some of the adverse effects of BA have only been reported in case reports or case series. Most reactions to BA reported thus far have been in association with antitumor necrosis factor-α agents, which is not surprising, as these are the most widely-used BA. In the present study, the orofacial adverse effects are reported with various BA in order to sensitize clinicians to the possibilities. In addition, we briefly summarize the mode of action and indications of these BA. As the use and range of BA increases, the number and diversity of adverse effects might well increase. Despite the adverse effects of biological agents, these may often be less serious than the adverse effects of the more traditional immunosuppressive agents.

Targeting angiogenesis and tumor microenvironment in metastatic colorectal cancer: role of aflibercept

In the last decades, we have progressively observed an improvement in therapeutic options for metastatic colorectal cancer (mCRC) treatment with a progressive prolongation of survival. mCRC prognosis still remains poor with low percentage of 5-year survival. Targeted agents have improved results obtained with standard chemotherapy. Angiogenesis plays a crucial role in colorectal cancer growth, proliferation, and metastasization and it has been investigated as a potential target for mCRC treatment. Accordingly, novel antiangiogenic targeted agents bevacizumab, regorafenib, and aflibercept have been approved for mCRC treatment as the result of several phase III randomized trials. The development of a tumor permissive microenvironment via the aberrant expression by tumor cells of paracrine factors alters the tumor-stroma interactions inducing an expansion of proangiogenic signals. Recently, the VELOUR study showed that addition of aflibercept to FOLFIRI regimen as a second-line therapy for mCRC improved significantly OS, PFS, and RR. This molecule represents a valid second-line therapeutic option and its peculiar ability to interfere with placental growth factor (PlGF)/vascular endothelial growth factor receptor 1 (VEGFR1) axis makes it effective in targeting angiogenesis, inflammatory cells and in overcoming resistances to anti-angiogenic first-line treatment. Here, we discuss about Aflibercept peculiar ability to interfere with tumor microenvironment and angiogenic pathway.

Antibody-based therapy in colorectal cancer

Treatment in patients with nonresectable and resectable colorectal cancer at the advanced stage is challenging, therefore intensive strategies such as chemotherapy, signaling inhibitors and monoclonal antibodies (mAbs) to control the disease are required. mAbs are particularly promising tools owing to their target specificities and strong antitumor activities through multiple mechanisms, as shown by rituximab in B-cell non-Hodgkin's lymphoma and trastuzumab in breast cancer. Three mAbs (cetuximab, bevacizumab and panitumumab) have been approved for the treatment of colorectal cancer in the USA and many other mAbs are being tested in clinical trials. The potential of antibody therapy is associated with several mechanisms including interference of vital signaling pathways targeted by the antibody and immune cytotoxicity selectively directed against tumor cells by tumor-bound antibody through the Fc portion of the antibody, such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. Moreover, recent experimental findings have shown that immune complexes formed by therapeutic mAbs with tumor-released antigens could augment the induction of tumor-specific cytotoxic CD8(+) T cells through activation of APCs. In addition, antibodies targeting immune checkpoints on hematopoietic cells have recently opened a new avenue for the treatment of cancer. In this review, we focus on mAb treatment in colorectal cancer and its immunological aspects.

Mutational analyses of epidermal growth factor receptor and downstream pathways in adrenocortical carcinoma

BACKGROUND

Adrenocortical carcinoma (ACC) is a rare disease with a poor prognosis and limited therapeutic options. Mitotane is considered the standard first-line therapy with only 30% of the patients showing objective tumour response. Defining predictive factors for response is therefore of clinical importance. The epidermal growth factor receptor (EGFR) has been implicated in the development of one-third of all malignancies. EGFR pathway members in ACC have been investigated, however, without available clinical data and relation to survival.

METHODS

In this study, mutation status of EGFR and downstream signalling pathways was evaluated in 47 ACC patients on mitotane using direct sequencing, a TaqMan allele-specific assay and immunohistochemistry. Archival formalin-fixed paraffin-embedded tumour tissue was used for all analyses. Patient data were obtained anonymously, after coupling with the collected tumour tissue.

RESULTS

One BRAF, two EGFR TK domain (c.2590> A, p.864A>T) and 11 TP53, but no PIK3CA or KRAS, mutations were found. No relationship was found between mutation status, immunostaining and mitotane response or survival.

CONCLUSION

In conclusion, our data suggest that the role of EGFR tyrosine kinase inhibitors in ACC is limited. Treatment with EGFR monoclonal antibodies on the other hand might be beneficial for a larger group of patients. The possible efficacy of this therapy in ACC should be evaluated in future trials.

Omics and drug response

A new generation of technologies commonly named omics permits assessment of the entirety of the components of biological systems and produces an explosion of data and a major shift in our concepts of disease. These technologies will likely shape the future of health care. One aspect of these advances is that the data generated document the uniqueness of each human being in regard to disease risk and treatment response. These developments have reemphasized the concept of personalized medicine. Here we review the impact of omics technologies on one key aspect of personalized medicine: the individual drug response. We describe how knowledge of different omics may affect treatment decisions, namely drug choice and drug dose, and how it can be used to improve clinical outcomes.

Using companion and coupled diagnostics within strategy to personalize targeted medicines

Regulatory authorities expect the pharmaceutical and biotechnology industries to accelerate their development of companion diagnostics and companion therapeutics towards the goal of personalized medicine, and expect health services to fund, prescribers to adopt and patients to accept these new therapeutic technologies. Expected benefits from more systematic development of combination products (companion diagnostic and its companion therapeutic) are expected to include safer and improved clinical and cost-effective use of medicines, more efficient patient selection for clinical trials, more cost-effective treatment pathways for health services, and a more profitable approach for drug developers. This review discusses challenges to timely development of companion diagnostics and provides case studies of single and multiple protein and genetic biomarkers of clinical response and risk of adverse drug effects.