An analysis of the treatment effect of panitumumab on overall survival from a phase 3, randomized, controlled, multicenter trial (20020408) in patients with chemotherapy refractory metastatic colorectal cancer

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

A cautionary tale: an evaluation of the performance of treatment switching adjustment methods in a real world case study

BACKGROUND

Treatment switching in randomised controlled trials (RCTs) is a problem for health technology assessment when substantial proportions of patients switch onto effective treatments that would not be available in standard clinical practice. Often statistical methods are used to adjust for switching: these can be applied in different ways, and performance has been assessed in simulation studies, but not in real-world case studies. We assessed the performance of adjustment methods described in National Institute for Health and Care Excellence Decision Support Unit Technical Support Document 16, applying them to an RCT comparing panitumumab to best supportive care (BSC) in colorectal cancer, in which 76% of patients randomised to BSC switched onto panitumumab. The RCT resulted in intention-to-treat hazard ratios (HR) for overall survival (OS) of 1.00 (95% confidence interval [CI] 0.82-1.22) for all patients, and 0.99 (95% CI 0.75-1.29) for patients with wild-type KRAS (Kirsten rat sarcoma virus).

METHODS

We tested several applications of inverse probability of censoring weights (IPCW), rank preserving structural failure time models (RPSFTM) and simple and complex two-stage estimation (TSE) to estimate treatment effects that would have been observed if BSC patients had not switched onto panitumumab. To assess the performance of these analyses we ascertained the true effectiveness of panitumumab based on: (i) subsequent RCTs of panitumumab that disallowed treatment switching; (ii) studies of cetuximab that disallowed treatment switching, (iii) analyses demonstrating that only patients with wild-type KRAS benefit from panitumumab. These sources suggest the true OS HR for panitumumab is 0.76-0.77 (95% CI 0.60-0.98) for all patients, and 0.55-0.73 (95% CI 0.41-0.93) for patients with wild-type KRAS.

RESULTS

Some applications of IPCW and TSE provided treatment effect estimates that closely matched the point-estimates and CIs of the expected truths. However, other applications produced estimates towards the boundaries of the expected truths, with some TSE applications producing estimates that lay outside the expected true confidence intervals. The RPSFTM performed relatively poorly, with all applications providing treatment effect estimates close to 1, often with extremely wide confidence intervals.

CONCLUSIONS

Adjustment analyses may provide unreliable results. How each method is applied must be scrutinised to assess reliability.

Application of Real-World Data to External Control Groups in Oncology Clinical Trial Drug Development

Randomized controlled trials (RCTs) that assess overall survival are considered the "gold standard" when evaluating the efficacy and safety of a new oncology intervention. However, single-arm trials that use surrogate endpoints (e.g., objective response rate or duration of response) to evaluate clinical benefit have become the basis for accelerated or breakthrough regulatory approval of precision oncology drugs for cases where the target and research populations are relatively small. Interpretation of efficacy in single-arm trials can be challenging because such studies lack a standard-of-care comparator arm. Although an external control group can be based on data from other clinical trials, using an external control group based on data collected outside of a trial may not only offer an alternative to both RCTs and uncontrolled single-arm trials, but it may also help improve decision-making by study sponsors or regulatory authorities. Hence, leveraging real-world data (RWD) to construct external control arms in clinical trials that investigate the efficacy and safety of drug interventions in oncology has become a topic of interest. Herein, we review the benefits and challenges associated with the use of RWD to construct external control groups, and the relevance of RWD to early oncology drug development.

Safety and efficacy of panitumumab in combination with trifluridine/tipiracil for pre-treated patients with unresectable, metastatic colorectal cancer with wild-type RAS: The phase 1/2 APOLLON study

BACKGROUND

We aimed to assess the safety and efficacy of combination treatment with panitumumab plus trifluridine/tipiracil (FTD/TPI) in patients with wild-type RAS metastatic colorectal cancer (mCRC) who were refractory/intolerant to standard therapies other than anti-epidermal growth factor receptor therapy.

METHODS

APOLLON was an open-label, multicentre, phase 1/2 trial. In the phase 1 part, 3 + 3 de-escalation design was used to investigate the recommended phase 2 dose (RP2D); all patients in the phase 2 part received the RP2D. The primary endpoint was investigator-assessed progression-free survival (PFS) rate at 6 months. Secondary endpoints included PFS, overall survival (OS), overall response rate (ORR), disease control rate (DCR), time to treatment failure (TTF), and safety.

RESULTS

Fifty-six patients were enrolled (phase 1, n = 7; phase 2, n = 49) at 25 Japanese centres. No dose-limiting toxicities were observed in patients receiving panitumumab (6 mg/kg every 2 weeks) plus FTD/TPI (35 mg/m2 twice daily; days 1-5 and 8-12 in a 28-day cycle), which became RP2D. PFS rate at 6 months was 33.3% (90% confidence interval [CI] 22.8-45.3). Median PFS, OS, ORR, DCR, and TTF were 5.8 months (95% CI 4.5-6.5), 14.1 months (95% CI 12.2-19.3), 37.0% (95% CI 24.3-51.3), 81.5% (95% CI 68.6-90.8), and 5.8 months (95% CI 4.29-6.21), respectively. Neutrophil count decreased (47.3%) was the most common Grade 3/4 treatment-emergent adverse event. No treatment-related deaths occurred.

CONCLUSION

Panitumumab plus FTD/TPI exhibited favourable anti-tumour activity with a manageable safety profile and may be a therapeutic option for pre-treated mCRC patients.

Propensity Score Matching Analysis of the Effect of Payer Status on the Survival of Colon Cancer Patients

Background and objective

Colon cancer is one of the most common types of cancer globally. The factors that could affect colon cancer survival include age, stage, treatment, and other socioeconomic aspects. Payer status has been shown to be a significant predictor of cancer patient survival in retrospective studies. However, due to the limitations of retrospective studies, patient baseline characteristics between payer statuses are not comparable. Few studies have addressed the effect of payer status on the overall survival (OS) of patients using propensity score matching (PSM). In light of this, we conducted a study to examine the effect of payer status on the survival of colon cancer patients based on PSM.

Materials and methods 

About 66,493 stage II/III colon cancer patients aged 40-90 years and diagnosed between 2004 and 2015 were analyzed from a de-identified National Cancer Database (NCDB) file. All patients had undergone surgery, and patients who had received radiation therapy, hormone therapy, immunotherapy, palliative care, or therapies other than chemotherapy were excluded. Only private or Medicaid payer status was included. The propensity score was calculated by computing the probability of patients being in the Medicaid group using logistic regression. The PSMATCH procedure in the SAS software (SAS Inc., Gary, NC) was used to perform PSM on patients with Medicaid and private insurance. The greedy nearest neighbor matching method was used to match one Medicaid to one privately insured patient with a caliper of 0.2. At the same time, an exact match was done for gender, age group, race, and stage at diagnosis. Multivariate Cox regression was then used to estimate the effect of payer status on survival before and after PSM.

Results

Among the 66,493 patients, 90.3% were privately insured and 9.7% had Medicaid. In univariate analysis, payer status was found to be a significant predictor of OS. Prior to PSM, the median overall survival (MOS) for patients with private insurance was 12.75 years, while those with Medicaid had a MOS of 9.02 years. After PSM, 6,167 paired patients were matched, and patients with private insurance had a MOS of >12.82 years and Medicaid patients had a MOS of 8.88 years. After PSM, patients with Medicaid had a 50% increased risk of death, and payer status proved to be a statistically significant predictor of OS of colon cancer.

Conclusion

Based on our findings, as per the PSM method, payer status can be a significant predictor of survival among colon cancer patients. Also, chemotherapy, race, age, and other socioeconomic factors were also found to be significant predictors of OS. Further research should be conducted to investigate other covariates not studied here and the mediation effect of payer on the survival of cancer patients.

Risk factors for developing cardiac toxicities in cancer patients treated with panitumumab combination therapy

Aim: To evaluate the incidence and risk of cardiac toxicities associated with panitumumab in advanced cancer of Caucasian patients. Materials & methods: The incidence of cardiac toxicity was assessed by simple incidence rates and rates per 100 person-years. Univariate and multivariate Cox regression was conducted. Results: Panitumumab-containing therapy significantly increased the risk of developing cardiac arrhythmias (p = 0.036), but not for any cardiac event (p = 0.24) or ischemic event (p = 0.087). The absolute rate of developing cardiac arrhythmia was 10.0 events versus 7.5 events per 100 person-years. Pre-existing hypertension (p = 0.033), history of cardiac disease (p = 0.055) or panitumumab usage (p = 0.046) were risk factors for cardiac arrhythmias. Conclusion: The addition of panitumumab to chemotherapy increases the risk of developing cardiac arrhythmia, but not for any cardiac toxicity or ischemic events.

Report from the 20th annual Western Canadian Gastrointestinal Cancer Consensus Conference; Saskatoon, Saskatchewan; 28-29 September 2018

The 20th annual Western Canadian Gastrointestinal Cancer Consensus Conference was held in Saskatoon, Saskatchewan, 28-29 September 2018. This interactive multidisciplinary conference is attended by health care professionals from across Western Canada (British Columbia, Alberta, Saskatchewan, and Manitoba) who are involved in the care of patients with gastrointestinal cancers. In addition, invited speakers from other provinces participate. Surgical, medical, and radiation oncologists, and allied health care professionals participated in presentations and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses current issues in the management of colorectal cancers.

Pan-Asian adapted ESMO consensus guidelines for the management of patients with metastatic colorectal cancer: a JSMO-ESMO initiative endorsed by CSCO, KACO, MOS, SSO and TOS

The most recent version of the European Society for Medical Oncology (ESMO) consensus guidelines for the treatment of patients with metastatic colorectal cancer (mCRC) was published in 2016, identifying both a more strategic approach to the administration of the available systemic therapy choices, and a greater emphasis on the use of ablative techniques, including surgery. At the 2016 ESMO Asia Meeting, in December 2016, it was decided by both ESMO and the Japanese Society of Medical Oncology (JSMO) to convene a special guidelines meeting, endorsed by both ESMO and JSMO, immediately after the JSMO 2017 Annual Meeting. The aim was to adapt the ESMO consensus guidelines to take into account the ethnic differences relating to the toxicity as well as other aspects of certain systemic treatments in patients of Asian ethnicity. These guidelines represent the consensus opinions reached by experts in the treatment of patients with mCRC identified by the Presidents of the oncological societies of Japan (JSMO), China (Chinese Society of Clinical Oncology), Korea (Korean Association for Clinical Oncology), Malaysia (Malaysian Oncological Society), Singapore (Singapore Society of Oncology) and Taiwan (Taiwan Oncology Society). The voting was based on scientific evidence and was independent of both the current treatment practices and the drug availability and reimbursement situations in the individual participating Asian countries.

Evolution of Cancer Pharmacological Treatments at the Turn of the Third Millennium

The medical history of cancer began millennia ago. Historical findings of patients with cancer date back to ancient Egyptian and Greek civilizations, where this disease was predominantly treated with radical surgery and cautery that were often ineffective, leading to the death of patients. Over the centuries, important discoveries allowed to identify the biological and pathological features of tumors, without however contributing to the development of effective therapeutic approaches until the end of the 1800s, when the discovery of X-rays and their use for the treatment of tumors provided the first modern therapeutic approach in medical oncology. However, a real breakthrough took place after the Second World War, with the discovery of cytotoxic antitumor drugs and the birth of chemotherapy for the treatment of various hematological and solid tumors. Starting from this epochal turning point, there has been an exponential growth of studies concerning the use of new drugs for cancer treatment. The second fundamental breakthrough in the field of oncology and pharmacology took place at the beginning of the '80s, thanks to molecular and cellular biology studies that allowed the development of specific drugs for some molecular targets involved in neoplastic processes, giving rise to targeted therapy. Both chemotherapy and target therapy have significantly improved the survival and quality of life of cancer patients inducing sometimes complete tumor remission. Subsequently, at the turn of the third millennium, thanks to genetic engineering studies, there was a further advancement of clinical oncology and pharmacology with the introduction of monoclonal antibodies and immune checkpoint inhibitors for the treatment of advanced or metastatic tumors, for which no effective treatment was available before. Today, cancer research is always aimed at the study and development of new therapeutic approaches for cancer treatment. Currently, several researchers are focused on the development of cell therapies, anti-tumor vaccines, and new biotechnological drugs that have already shown promising results in preclinical studies, therefore, in the near future, we will certainly assist to a new revolution in the field of medical oncology.

An early clinical trial of Salirasib, an oral RAS inhibitor, in Japanese patients with relapsed/refractory solid tumors

Purpose

Patients with RAS-positive tumors respond poorly to chemotherapies and have a few treatment options. Salirasib is an oral RAS inhibitor that competitively blocks the membrane association of RAS proteins. The aim of this phase I multiple-ascending-dose clinical trial was to investigate the safety and pharmacokinetics of Salirasib in Japanese patients with relapsed/refractory solid tumors and to explore its efficacy.

Methods

Salirasib was started at a dose of 100-mg twice-daily and escalated to a maximum of 1000-mg twice-daily from days 1 to 21 of a 28-day regimen. The pharmacokinetics was evaluated on days 1 and 21. Dose-limiting toxicity (DLT) and adverse events (AEs) were monitored throughout the trial. Patients with stable disease or better repeated the dosing regimen.

Results

A total of 21 patients received Salirasib. Among 14 patients tested, 4 had KRAS mutations. C_max and AUC_inf were maximal at 800 mg. No maximum tolerable dose was discerned, as no DLT was observed in any dosing group. The most frequently observed AEs were gastrointestinal disturbances, including diarrhea, abdominal pain, and nausea. No AEs led to discontinuation. All patients completed the first regimen and 11 patients repeated the regimen (median: 2 cycles; range: 1–13). Patients with KRAS mutations showed median progression-free survival of 227 days (range: 79–373).

Conclusion

Salirasib was safe and well tolerated in Japanese patients, and 800-mg twice-daily is recommended for phase II trials. Although the number of participants with KRAS mutations was limited, the remarkably long progression-free period warrants further investigation.

Clinical trial registration

JAPIC Clinical Trials Information; JapicCTI-121751.

Electronic supplementary material

The online version of this article (10.1007/s00280-018-3618-4) contains supplementary material, which is available to authorized users.

Current companion diagnostics in advanced colorectal cancer; getting a bigger and better piece of the pie

While the treatment of colorectal cancer continues to rely heavily on conventional cytotoxic therapy, an increasing number of targeted agents are under development. Many of these treatments require companion diagnostic tests in order to define an appropriate population that will derive benefit. In addition, a growing number of biomarkers provide prognostic information about a patient's malignancy. As we learn more about these biomarkers and their assays, selecting the appropriate companion diagnostic becomes increasingly important. In the case of many biomarkers, there are numerous assays which could provide the same information to a treating physician, however each assay has strengths and weaknesses. Institutions must balance cost, assay sensitivity, turn-around time, and labor resources when selecting which assay to offer. In this review we will discuss the current state of companion diagnostics available in metastatic colorectal cancer and explore emerging biomarkers and their assays. We will focus on KRAS, BRAF, HER2, and PIK3CA testing, as well as microsatellite stability assessment and multigene panels.

A phase 3 trial evaluating panitumumab plus best supportive care vs best supportive care in chemorefractory wild-type KRAS or RAS metastatic colorectal cancer

BACKGROUND

We assessed the treatment effect of panitumumab plus best supportive care (BSC) vs BSC on overall survival (OS) in patients with chemorefractory wild-type KRAS exon 2 metastatic colorectal cancer (mCRC) and report the first prospective extended RAS analysis in a phase 3 trial.

METHODS

Patients with wild-type KRAS exon 2 mCRC were randomised 1 : 1 to panitumumab (6 mg kg^-1 Q2W) plus BSC or BSC. On-study crossover was prohibited. RAS mutation status was determined by central laboratory testing. The primary endpoint was OS in wild-type KRAS exon 2 mCRC; OS in wild-type RAS mCRC (KRAS and NRAS exons 2, 3, and 4) was a secondary endpoint.

RESULTS

Three hundred seventy seven patients with wild-type KRAS exon 2 mCRC were randomised. Median OS was 10.0 months with panitumumab plus BSC vs 7.4 months with BSC (HR=0.73; 95% CI=0.57-0.93; P=0.0096). RAS ascertainment was 86%. In wild-type RAS mCRC, median OS for panitumumab plus BSC was 10.0 vs 6.9 months for BSC (HR=0.70; 95% CI=0.53-0.93; P=0.0135). Patients with RAS mutations did not benefit from panitumumab (OS HR=0.99; 95% CI=0.49-2.00). No new safety signals were observed.

CONCLUSIONS

Panitumumab significantly improved OS in wild-type KRAS exon 2 mCRC. The effect was more pronounced in wild-type RAS mCRC, validating previous retrospective analyses.

Advances in Biomarkers: Going Beyond the Carcinoembryonic Antigen

Using biologically available markers to guide treatment decisions in colorectal cancer care is becoming increasingly common, though our understanding of these biomarkers is in its infancy. In this article, we will discuss how this area is rapidly changing, review important biomarkers being used currently, and explain how the results influence clinical decision-making. We will also briefly discuss the possibility of a liquid biopsy and explore several exciting and new options.

ESMO consensus guidelines for the management of patients with metastatic colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies in Western countries. Over the last 20 years, and the last decade in particular, the clinical outcome for patients with metastatic CRC (mCRC) has improved greatly due not only to an increase in the number of patients being referred for and undergoing surgical resection of their localised metastatic disease but also to a more strategic approach to the delivery of systemic therapy and an expansion in the use of ablative techniques. This reflects the increase in the number of patients that are being managed within a multidisciplinary team environment and specialist cancer centres, and the emergence over the same time period not only of improved imaging techniques but also prognostic and predictive molecular markers. Treatment decisions for patients with mCRC must be evidence-based. Thus, these ESMO consensus guidelines have been developed based on the current available evidence to provide a series of evidence-based recommendations to assist in the treatment and management of patients with mCRC in this rapidly evolving treatment setting.

Second-line panitumumab as a triweekly dose for patients with wild-type KRAS exon 2 metastatic colorectal cancer: a single-institution experience

OBJECTIVE

Panitumumab administered as monotherapy in colorectal cancer (CRC) has shown response and disease stabilization rates of approximately 30%. The current study aimed to evaluate the progression-free survival (PFS) and overall survival (OS) of patients with metastatic colorectal cancer (mCRC) treated with panitumumab every 3 weeks as a second line treatment.

METHODS

This study is a retrospective analysis of 18 patients, aged more than 18 years, with wild-type KRAS exon 2 mCRC treated with panitumumab as a second-line single agent after progression on first-line chemotherapy.

RESULTS

The median number of courses received was 10 (range, 4-29), and the median duration of treatment was 30 weeks (range, 12-96 weeks). After a median follow-up period of 13 months, the median PFS was 6 months (range, 4.3-7.7 months) and the median OS was 11 months (range, 7.4-14.5 months). The median PFS was 4 months for patients with < grade 2 skin toxicity and 6 months (range, 4.5-7.5 months) for patients with ≥grade 2 skin rash (P=0.05). The median OS was 9 months (range, 6.4-11.5 months) and 14 months (range, 11.6-16.3 months) for the two groups of patients (P=0.002).

CONCLUSIONS

Panitumumab given every 3 weeks is effective and well tolerated in patients with advanced CRC that progressed after standard chemotherapy.

Pharmacokinetic and pharmacodynamic evaluation of panitumumab in the treatment of colorectal cancer

INTRODUCTION

Integration of targeted therapy and additional chemotherapy options has improved median overall survival (OS) in patients with unresectable metastatic colorectal cancer (mCRC). Cetuximab and panitumumab are examples of targeted therapies, specifically against the epidermal growth factor receptor (EGFR). This review focuses on Panitumumab, a fully human IgG2 monoclonal antibody, which inhibits key oncogenic downstream cell signalling pathways. Panitumumab and cetuximab have improved tumour response rate, progression-free survival, and OS in mCRC patients in whom the RAS (Rat Sarcoma) gene is of Wild Type (WT) status.

AREAS COVERED

The EGFR signalling pathway and preclinical, Phase I and Phase II clinical studies on the pharmacokinetic, pharmacodynamic and safety evaluation of panitumumab are presented. Phase III studies utilising panitumumab in the first, second and third line setting in mCRC are also described.

EXPERT OPINION

Panitumumab exhibits excellent pharmacokinetics and pharmacodynamics by way of uncomplicated dosing, non-existent drug interactions, minimal infusion reactions and manageable side effects, making it a suitable target for combination treatments. However, innate and acquired resistances are still obstacles. To overcome this, experimented strategies are ongoing, particularly in patients with Her-2 and BRAF gene alterations. Novel biomarkers to improve patient selection and second-generation targeted antibodies are in development.

Epidermal growth factor receptor imaging in human head and neck cancer xenografts

Molecular imaging of specific biomarkers can have prognostic, predictive or monitoring value in head and neck squamous cell carcinoma (HNSCC). The epidermal growth factor receptor (EGFR) is involved in various radiation resistance mechanisms as it steers the pathways related to DNA damage repair, proliferation, hypoxia and apoptosis. Radiolabeled labeled F(ab')2 fragments of the EGFR antibody cetuximab can be applied for non-invasive imaging of this receptor. Preclinical studies have shown that radioresistant tumors had a higher tracer uptake after irradiation, probably due to upregulation of membranous EGFR, thereby increasing target availability possibly as a compensation mechanism. Tumors with increased EGFR availability were also more responsive to the EGFR inhibitor cetuximab. Potentially, radionuclide imaging of the EGFR can be applied for monitoring treatment regimens in clinical practice.

Extended RAS and BRAF Mutation Analysis Using Next-Generation Sequencing

Somatic mutations in KRAS, NRAS, and BRAF genes are related to resistance to anti-EGFR antibodies in colorectal cancer. We have established an extended RAS and BRAF mutation assay using a next-generation sequencer to analyze these mutations. Multiplexed deep sequencing was performed to detect somatic mutations within KRAS, NRAS, and BRAF, including minor mutated components. We first validated the technical performance of the multiplexed deep sequencing using 10 normal DNA and 20 formalin-fixed, paraffin-embedded (FFPE) tumor samples. To demonstrate the potential clinical utility of our assay, we profiled 100 FFPE tumor samples and 15 plasma samples obtained from colorectal cancer patients. We used a variant calling approach based on a Poisson distribution. The distribution of the mutation-positive population was hypothesized to follow a Poisson distribution, and a mutation-positive status was defined as a value greater than the significance level of the error rate (α = 2 x 10^-5). The cut-off value was determined to be the average error rate plus 7 standard deviations. Mutation analysis of 100 clinical FFPE tumor specimens was performed without any invalid cases. Mutations were detected at a frequency of 59% (59/100). KRAS mutation concordance between this assay and Scorpion-ARMS was 92% (92/100). DNA obtained from 15 plasma samples was also analyzed. KRAS and BRAF mutations were identified in both the plasma and tissue samples of 6 patients. The genetic screening assay using next-generation sequencer was validated for the detection of clinically relevant RAS and BRAF mutations using FFPE and liquid samples.

Risk/benefit profile of panitumumab-based therapy in patients with metastatic colorectal cancer: evidence from five randomized controlled trials

This study aims to evaluate the risk and benefit profiles of panitumumab-based therapy (PBT) in patients with metastatic colorectal cancer (mCRC). Relevant randomized controlled trials were identified by searching PubMed, Medline, EMBASE and Cochrane Library. Data on progression-free survival (PFS), overall survival (OS), all grade and severe (grade ≥3) adverse events were extracted and pooled to calculate hazard ratios (HRs) and risk ratios (RRs) with 95 % confidence intervals (CIs). Number needed to treat (NNT) for PFS and number needed to harm (NNH) for significantly changed toxicities were calculated. A total of 4,155 patients were included in the analysis. PBT significantly improved PFS (HRrandom = 0.66, 95 % CI = 0.45-0.95) but not OS (HRfixed = 0.93, 95 % CI = 0.83-1.04) when used in the subsequent-line setting. The effect on PFS was more evident in patients with wild-type KRAS (HRrandom = 0.64, 95 % CI = 0.47-0.87) and the NNT for PFS is 11 to 23at 1 year. PBT did not benefit patients when used in the first-line setting. In addition, PBT significantly increased the risk of skin toxicity, infections, diarrhea, dehydration, mucositis, hypokalemia, fatigue, hypomagnesemia, pulmonary embolism and paronychia. The NNHs for skin toxicity, diarrhea, infection, hypokalemia and mucositis are less than 23. In conclusion, when used in the subsequent-line setting, PBT can improve the disease progression, especially in mCRC patients with wild-type KRAS. Regarding the adverse events associated with the PBT, close monitoring and necessary preparations are recommended during the therapy.

Monoclonal Antibodies in Cancer Therapy: Mechanisms, Successes and Limitations

Rituximab was the first chemotherapeutic monoclonal antibody (CmAb) approved for clinical use in cancer therapeutics in 1997 and has significantly improved the clinical outcomes in non-Hodgkin's lymphoma. Since then, numerous CmAbs have been developed and approved for the treatment of various haematologic and solid human cancers. In this review, the classification, efficacy and significantly reduced toxicity of CmAbs available for use in the United States of America are presented. Finally, the limitations of CmAbs and future considerations are explored.

Targeted therapy in gastrointestinal malignancies

Increased understanding of cancer pathogenesis has identified several pathways that serve as potential targets for novel targeted agents in development. The selection of targeted cancer therapy based on biomarkers has instigated a new era of personalized medicine and changed the way we practice oncology. Many targeted agents are approved for treatment of gastrointestinal malignancies most targeting tumor angiogenesis, and many more are in different phases of development. Here we briefly summarize nine different targeted agents that are approved currently in the U.S. and several other agents currently being studied in various gastrointestinal cancers.