An open-label, single-arm study assessing safety and efficacy of panitumumab in patients with metastatic colorectal cancer refractory to standard chemotherapy

Safety and pharmacokinetics of panitumumab in Japanese patients with advanced solid tumors

BACKGROUND

Panitumumab is a fully human, monoclonal antibody against the epidermal growth factor receptor. Previous studies in non-Japanese patients with solid tumors showed that panitumumab exhibited nonlinear pharmacokinetics, was well tolerated (skin toxicities were the most common treatment-related adverse events), and had antitumor activity in some patients. This open-label, phase 1 study investigated panitumumab safety and pharmacokinetics in Japanese patients.

METHODS

Japanese patients with advanced solid tumors were enrolled into one of three sequential panitumumab dose cohorts (cohort 1, 2.5 mg/kg weekly; cohort 2, 6.0 mg/kg every 2 weeks; and cohort 3, 9.0 mg/kg every 3 weeks) and received panitumumab until disease progression or drug intolerability. Safety endpoints included the incidence of adverse events, changes in laboratory values, and the appearance of anti-panitumumab antibodies. Serial pharmacokinetic samples were collected after the first and third doses of panitumumab. Tumors were assessed at week 8 and every 8 weeks thereafter.

RESULTS

Eighteen patients (6 per cohort) were enrolled. No dose-limiting toxicities, investigator-reported infusion reactions, or deaths occurred. Seven patients had grade-3/4 adverse events; fatigue and anorexia were most common. The most common skin toxicities were rash and acneiform dermatitis. No neutralizing anti-panitumumab antibodies were detected. Panitumumab exhibited nonlinear pharmacokinetics, and antitumor activity was observed in 31% (4/13) of the patients with colorectal cancer.

CONCLUSION

In Japanese patients with solid tumors, panitumumab was well tolerated, demonstrated pharmacokinetic and safety profiles similar to those observed previously in non-Japanese patients, and exhibited encouraging antitumor activity in patients with colorectal cancer.

Improving disease control in advanced colorectal cancer: Panitumumab and cetuximab

Colorectal cancer remains a major public health concern in Europe and North America. It is responsible for one million new cases and half a million deaths per year worldwide. During the past few years new effective treatments have evolved improving the outcome of patients with this disease. Several alternatives are currently available for advanced colorectal cancer patients including different chemotherapeutic regimens (fluoropyrimidines, irinotecan and oxaliplatin) and targeted therapies such as bevacizumab and cetuximab. Different combinations achieve a median survival of over 2 years. Intense efforts focus on identifying agents targeting growth factor receptors, signal transduction pathways or angiogenesis mediators. One of the last available drugs for the management of advanced colorectal cancer is panitumumab, a well-tolerated and effective anti-EGFR monoclonal antibody approved as a single agent in chemotherapy refractory patients. We discuss the current evidence supporting panitumumab for metastatic colorectal cancer treatment, potential predictive biomarkers and ongoing clinical trials with different combinations including panitumumab.

Integration of panitumumab into the treatment of colorectal cancer

Conventional chemotherapy increases progression-free survival (PFS) and overall survival (OS) of metastatic colorectal cancer (mCRC) patients versus best supportive care (BSC). However, the efficacy of chemotherapy is limited. Recently approved monoclonal antibodies (MoAb) have a different mechanism of action, targeting growth factors or their receptors. Panitumumab is a fully human IgG2 MoAb directed against the epidermal growth factor receptor (EGFR). In phase II trials, panitumumab showed preliminary activity in chemorefractory mCRC. This efficacy was confirmed in a randomized pivotal phase III trial, which compared single-agent panitumumab plus BSC versus BSC alone. Several ongoing clinical trials are evaluating panitumumab in combination with different chemotherapy regimens in first- and second-line settings. Skin toxicities, hypomagnesemia, and diarrhea are the most common adverse events associated with anti-EGFR therapy. KRAS status and skin rash have been correlated with panitumumab efficacy. This article reviews the preclinical and pharmacokinetics data, activity and tolerance of panitumumab in mCRC patients. Potential predictive factors of response are also discussed.

Radiochemotherapy in locally advanced squamous cell carcinomas of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is a common disease that develops in the upper aerodigestive epithelium. The most important risk factors are tobacco and alcohol consumption. There is also increasing evidence that human papillomavirus plays an important role in the cause of SCCHN. The complex anatomy, the vital functions of the upper aerodigestive tract and the close proximity to vital structures, explain that the goal of treatment is not only to improve survival outcomes, but also to preserve organ function. Radiotherapy and surgery are the standard modalities of treatment, reflecting the locoregional predominance of SCCHN. Chemotherapy plays an important role in the treatment of patients with locoregionally advanced disease, in conjunction with radiotherapy and surgery. Indeed, standard therapy for resectable locoregionally advanced (stage III or IV) SCCHN cancers consists either of surgery and adjuvant chemoradiotherapy or definitive concomitant chemoradiotherapy, depending upon disease site, stage and resectability of the tumour, or institutional experience. Concomitant chemoradiotherapy has been shown in several randomised trials to improve disease-free and overall survival in the postoperative setting for resected disease with poor prognostic factors. Furthermore, multiple randomised studies and meta-analyses have shown that definitive chemoradiotherapy, as well anti-epidermal growth factor receptor treatment in one randomised study, improved disease-free and overall survival when compared with radiotherapy alone. This overview reviews the most relevant published studies on the multidisciplinary management of SCCHN and discusses future strategies to reduce locoregional failures.

Association of progression-free survival, overall survival, and patient-reported outcomes by skin toxicity and KRAS status in patients receiving panitumumab monotherapy

BACKGROUND

The authors explored the association of skin toxicity (ST) severity as measured by patient-reported ST and Common Terminology Criteria for Adverse Events (CTCAE) grading with efficacy of panitumumab, a fully human antiepidermal growth factor receptor antibody, from a phase 3 metastatic colorectal cancer (CRC) trial.

METHODS

Patients were randomized to panitumumab plus best supportive care (BSC) vs BSC alone. ST by modified National Cancer Institute CTCAE v3.0 and modified Dermatology Life Quality Index (mDLQI), health-related quality of life (HRQOL), and CRC symptoms were measured. ST was analyzed using a landmark approach. Associations by KRAS mutational status were also assessed.

RESULTS

Of 463 patients, 208 of 231 (90%) panitumumab patients and 184 of 232 (79%) BSC patients had > or = 1 postbaseline patient-reported outcome (PRO) assessment. Panitumumab patients with more severe ST had significantly longer overall survival (OS) (grade 2-4:grade 1; hazard ratio, 0.60; P = .0033). Lower mDLQI scores (< 67; more bothersome ST) were associated with longer OS (Cox model, P < .0001). Similar results were observed with progression-free survival (PFS). An inverse relation between mDLQI and HRQOL scores was observed, suggesting that ST bother correlated with better HRQOL. KRAS and PRO data were available in 363 patients (188 panitumumab; 175 BSC). Longer OS was associated with lower mDLQI scores, regardless of KRAS status. Longer PFS was associated with more severe ST (lower mDLQI scores and higher CTCAE grade ST) in patients with wild-type (WT) KRAS tumors, but not in patients with mutant KRAS tumors.

CONCLUSIONS

More severe ST, by both clinical grading and PRO, is associated with better CRC symptoms and HRQOL and with longer OS and PFS among panitumumab-treated patients. The associations for PFS were more pronounced in patients with WT KRAS tumors.

Clinical Efficacy and Toxicity of Anti-EGFR Therapy in Common Cancers

Epidermal growth factor receptor (EGFR) is a cell surface molecule and member of the ErbB family of receptor tyrosine kinases. Its activation leads to proliferation, antiapoptosis, and metastatic spread, making inhibition of this pathway a compelling target. In recent years, an increasing number of clinical trials in the management of solid malignancies have become available indicating the clinical efficacy of anti-EGFR monoclonal antibodies and oral small molecule tyrosine kinase inhibitors (TKIs). This review addresses frequently used EGFR inhibitors, summarizes clinical efficacy data of these new therapeutic agents, and discusses their associated toxicity and management.

Successful desensitization with cetuximab after an infusion reaction to panitumumab in patients with metastatic colorectal cancer

BACKGROUND

Cetuximab and panitumumab are chimeric and fully human monoclonal antibodies, respectively, against epidermal growth factor receptor used in the treatment of metastatic colorectal cancer (mCRC). Incidence of documented infusion reaction (IR) is more common with cetuximab (all grades [g]: 15-21%, g 3/4: 2-5%) than panitumumab (all g: 4%, g 3/4: 1%). Anecdotal reports suggest successful challenge with panitumumab following IR with cetuximab (Saif et al. in Cancer Chemother Pharmacol 63(6):1017-1022, 2009). However, safety of cetuximab after IR with panitumumab is not known. We report two patients successfully desensitized with cetuximab after IR with panitumumab.

PATIENTS AND METHODS

A 42-year-old female with mCRC received panitumumab as a third-line agent. She developed severe chest tightness, pain, and shortness of breath (SOB), 5 min after first panitumumab infusion. A second 70-year-old male with mCRC developed severe facial flushing, back pain, SOB, tachycardia and hypotension, 5 min after second dose of panitumumab plus irinotecan as a second-line therapy. These two patients received desensitization protocol for cetuximab after a test dose of 20 mg IV over 10 min followed by a slow infusion 10% of original rate in 0-2 h, 25% of original rate in 2-2.5 h, 50% reduced rate in 2.5-3 h, and then 100% infusion rate after 3 h. Patients were observed 4 h after completion of infusion.

RESULTS

First patient received a total of 12 cycles of cetuximab with stable disease, no recurrence of IR, and grade 1-2 acniform rash that first developed after third cycle. Second patient received a total of eight cycles uneventfully without IR.

CONCLUSIONS

To our knowledge, this is the first report of two patients with documented IR with panitumumab being desensitized successfully with cetuximab. Though anecdotal reports suggest safety of panitumumab in patients following IR with cetuximab, panitumumab can also cause severe IR. Our experience suggests that in case of limited options, such patients can be successfully challenged with cetuximab in a hospital after appropriate desensitization and premedication. Further studies focusing on desensitization and identifying hypersensitivity profile of different anti-epidermal growth factor receptor antibodies are warranted.

An open-label clinical trial evaluating safety and pharmacokinetics of two dosing schedules of panitumumab in patients with solid tumors

PURPOSE

This study evaluated safety, pharmacokinetics, and efficacy of 2 dose schedules and 2 infusion times of panitumumab in patients with advanced solid malignancies.

PATIENTS AND METHODS

This phase I multicenter, open-label study sequentially enrolled patients with advanced solid tumors refractory to standard therapy, or for which no standard therapy exists, to receive panitumumab 6 mg/kg every 2 weeks or 9 mg/kg every 3 weeks. Patients receiving panitumumab every 2 weeks received either all infusions over 60 minutes or a 60-minute infusion for the first dose followed by 30-minute infusions if the first infusion was well tolerated. Patients in the every-3-week cohort received 60-minute infusions. Safety outcomes included the incidence of adverse events and antipanitumumab antibody formation. Pharmacokinetic properties were determined. Efficacy endpoints included response rate and duration of response.

RESULTS

Eighty-six patients were enrolled; 84 (98%) received panitumumab. Treatment-related adverse events occurred in 90% of patients. Safety profiles were similar between patients receiving 30-minute (n = 20) and 60-minute (n = 43) infusions every 2 weeks and patients receiving panitumumab every 3 weeks (n = 21). Panitumumab exposure at steady state increased dose proportionally, and peak serum concentrations were similar in patients receiving either 30- or 60-minute infusions every 2 weeks. Objective responses were seen in 4 patients (5%) with colon, rectal, esophageal, and bladder cancers.

CONCLUSION

Similar drug exposures and safety profiles were observed in patients receiving panitumumab 6 mg/kg every 2 weeks with either 30- or 60-minute infusions and antitumor activity was seen in some patients. Exposure increased approximately dose proportionally at steady state.

A phase 2 clinical trial of panitumumab monotherapy in Japanese patients with metastatic colorectal cancer

OBJECTIVE

Panitumumab, a fully human monoclonal antibody targeting epidermal growth factor receptor (EGFR), has antitumor activity and an acceptable safety profile in patients with metastatic colorectal cancer (mCRC). This Phase 2 study evaluated efficacy, pharmacokinetics and safety of panitumumab in Japanese patients with mCRC who developed progressive disease during or after fluoropyrimidine, irinotecan and oxaliplatin chemotherapy.

METHODS

Eligible patients had histologically proven colorectal adenocarcinoma and EGFR tumor expression in > or =1% of tumor cells by immunohistochemistry. Patients received panitumumab 6 mg/kg every 2 weeks until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) per modified Response Evaluation Criteria in Solid Tumors (RECIST) by independent central review. Secondary endpoints included progression-free survival (PFS), overall survival (OS), pharmacokinetic parameters and incidence of adverse events.

RESULTS

Fifty-two patients received at least one dose of panitumumab. Seven patients had partial responses for a confirmed ORR of 13.5% (95% CI: 5.6, 25.8). Median PFS was 8.0 weeks (95% CI: 7.4, 11.4) and median OS was 9.3 months (95% CI: 7.1, 12.8). Panitumumab pharmacokinetics were consistent with prior studies in Japanese and non-Japanese patients. The most common treatment-related adverse events (all, worst grade 3) were acne (81%, 2%), dry skin (62%, 0%), rash (46%, 2%), paronychia (33%, 2%), pruritus (33%, 0%) and hypomagnesemia (33%, 0%). No adverse event of infusion reaction was reported by the investigators.

CONCLUSIONS

Panitumumab monotherapy was active in Japanese patients with chemotherapy-refractory mCRC, with pharmacokinetic and safety profiles similar to those seen in prior studies.

Panitumumab-Related Hypomagnesemia in Patients with Colorectal Cancer

Purpose

Hypomagnesemia is an adverse reaction associated with epidermal growth factor receptor (EGFR)-targeting monoclonal antibodies. Of the 2 EGFR antibodies approved by the US Food and Drug Administration—cetuximab and panitumumab—cetuximab-induced hypomagnesemia has been extensively characterized but panitumumab-induced hypomagnesemia has not.

Methods

In this retrospective study, the clinical course of hypomagnesemia is described in three 64- to 68-year-old men who received panitumumab monotherapy or panitumumab-plus-irinotecan therapy for colorectal cancer for 8 to 21 weeks.

Results

The onset of hypomagnesemia was variable, ranging from 1 week to 10 weeks following the initiation of panitumumab. Magnesium levels did not normalize until 4 to 8 weeks after discontinuation of the agent. Of the patients in the study, 2 had new onset of grade 3 hypomagnesemia 1 to 3 weeks after panitumumab was discontinued. Management was magnesium sulfate 2 g infusion weekly and magnesium oxide 1,200 mg oral repletion daily. With severe hypomagnesemia (grade 3 and higher) or significant diarrhea (grade 3 and higher), a daily infusion of magnesium sulfate 2 or 4 g was administered.

Conclusion

When administering panitumumab therapy, magnesium levels should be monitored from the initiation of the agent to at least 8 weeks following cessation. Hypomagnesemia usually can be managed with magnesium sulfate 2 to 4 g infusion weekly and magnesium oxide 1,200 mg oral repletion daily. Future research is warranted to identify simple and efficient strategies for monitoring and treating EGFR blockade with monoclonal antibody-associated hypomagnesemia.

Clinical use of anti-epidermal growth factor receptor monoclonal antibodies in metastatic colorectal cancer

Abstract Cetuximab and panitumumab, monoclonal antibodies used to target the epidermal growth factor receptor (EGFR), were recently approved by the United States Food and Drug Administration for use as single agents or in combination with other chemotherapy drugs in the treatment of metastatic colorectal cancer. The anti-EGFR monoclonal antibodies, either as single agents or in combination with chemotherapy, have demonstrated clinical activity in this setting. When combined with standard cytotoxic chemotherapy or other targeted agents (e.g., bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody), anti-EGFR monoclonal antibodies have been well tolerated and produced minimal toxicities. However, cetuximab and panitumumab appear to benefit only select patients. Predictive markers of efficacy, including EGFR overexpression, development of skin rash, and the absence of a K-ras mutation, have been evaluated in clinical studies to identify patients likely to respond to anti-EGFR monoclonal antibody therapy. This review discusses recent clinical studies of anti-EGFR monoclonal antibodies in the treatment of metastatic colorectal cancer, predictive markers of their efficacy, and common toxicities associated with their use.

Anti-epidermal growth factor receptor monotherapy in the treatment of metastatic colorectal cancer: where are we today?

Over the past 10 years there has been a significant increase in the armamentarium of agents available for use in the treatment of advanced colorectal cancer (CRC). Among these new agents are two monoclonal antibodies targeting the epidermal growth factor receptor (EGFR): cetuximab, a mouse-human chimeric monoclonal antibody, and panitumumab, a fully human monoclonal antibody. Both are approved as monotherapy for the treatment of chemotherapy-refractory advanced CRC. Cetuximab is also indicated for use in combination with irinotecan. Here, we review 10 reports of phase II and III clinical studies of patients treated with panitumumab or cetuximab monotherapy. The clinical trials demonstrate similar efficacy profiles for advanced CRC patients treated with panitumumab and cetuximab monotherapy, with some differences in their adverse event profiles. In addition, the recent results of retrospective tumor KRAS gene mutational analyses in CRC patients treated with anti-EGFR monotherapy are reviewed. Data from the clinical trials reviewed here clearly demonstrate that anti-EGFR monotherapy is an effective treatment modality for patients with chemotherapy-refractory advanced CRC.

A randomized phase IIIB trial of chemotherapy, bevacizumab, and panitumumab compared with chemotherapy and bevacizumab alone for metastatic colorectal cancer

PURPOSE

Panitumumab, a fully human antibody targeting the epidermal growth factor receptor, is active in patients with metastatic colorectal cancer (mCRC). This trial evaluated panitumumab added to bevacizumab and chemotherapy (oxaliplatin- and irinotecan-based) as first-line treatment for mCRC.

PATIENTS AND METHODS

Patients were randomly assigned within each chemotherapy cohort to bevacizumab and chemotherapy with or without panitumumab 6 mg/kg every 2 weeks. The primary end point was progression-free survival (PFS) within the oxaliplatin cohort. Tumor assessments were performed every 12 weeks and reviewed centrally.

RESULTS

A total of 823 and 230 patients were randomly assigned to the oxaliplatin and irinotecan cohorts, respectively. Panitumumab was discontinued after a planned interim analysis of 812 oxaliplatin patients showed worse efficacy in the panitumumab arm. In the final analysis, median PFS was 10.0 and 11.4 months for the panitumumab and control arms, respectively (HR, 1.27; 95% CI, 1.06 to 1.52); median survival was 19.4 months and 24.5 months for the panitumumab and control arms, respectively. Grade 3/4 adverse events in the oxaliplatin cohort (panitumumab v control) included skin toxicity (36% v 1%), diarrhea (24% v 13%), infections (19% v 10%), and pulmonary embolism (6% v 4%). Increased toxicity without evidence of improved efficacy was observed in the panitumumab arm of the irinotecan cohort. KRAS analyses showed adverse outcomes for the panitumumab arm in both wild-type and mutant groups.

CONCLUSION

The addition of panitumumab to bevacizumab and oxaliplatin- or irinotecan-based chemotherapy results in increased toxicity and decreased PFS. These combinations are not recommended for the treatment of mCRC in clinical practice.

Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer

PURPOSE Cetuximab or panitumumab are effective in 10% to 20% unselected metastatic colorectal cancer (CRC) patients. KRAS mutations account for approximately 30% to 40% patients who are not responsive. The serine-threonine kinase BRAF is the principal effector of KRAS. We hypothesized that, in KRAS wild-type patients, BRAF mutations could have a predictive/prognostic value. PATIENTS AND METHODS We retrospectively analyzed objective tumor responses, time to progression, overall survival (OS), and the mutational status of KRAS and BRAF in 113 tumors from cetuximab- or panitumumab-treated metastatic CRC patients. The effect of the BRAF V600E mutation on cetuximab or panitumumab response was also assessed using cellular models of CRC. Results KRAS mutations were present in 30% of the patients and were associated with resistance to cetuximab or panitumumab (P = .011). The BRAF V600E mutation was detected in 11 of 79 patients who had wild-type KRAS. None of the BRAF-mutated patients responded to treatment, whereas none of the responders carried BRAF mutations (P = .029). BRAF-mutated patients had significantly shorter progression-free survival (P = .011) and OS (P < .0001) than wild-type patients. In CRC cells, the introduction of BRAF V600E allele impaired the therapeutic effect of cetuximab or panitumumab. Treatment with the BRAF inhibitor sorafenib restored sensitivity to panitumumab or cetuximab of CRC cells carrying the V600E allele. CONCLUSION BRAF wild-type is required for response to panitumumab or cetuximab and could be used to select patients who are eligible for the treatment. Double-hit therapies aimed at simultaneous inhibition of epidermal growth factor receptor and BRAF warrant exploration in CRC patients carrying the V600E oncogenic mutation.

Salvage radioembolization of liver-dominant metastases with a resin-based microsphere: initial outcomes

PURPOSE

The use of radioembolization of hepatic metastases with yttrium-90 ((90)Y) microspheres is increasing. The present report describes the outcomes in a cohort of patients with metastatic liver tumors treated with a resin-based microsphere agent.

MATERIALS AND METHODS

Thirty patients with colon (n = 13), breast (n = 7), and other primary cancers (n = 10) were treated after the failure of first- and second-line therapy. Overall survival (OS), time to progression (TTP), and time to treatment failure (TTTF) were calculated from the first treatment. Response was measured according to Response Evaluation Criteria In Solid Tumors at interval follow-up imaging.

RESULTS

Thirty patients underwent 56 infusions of (90)Y, and 18 remained alive at the end of the study. Fourteen patients (47%) had a partial response or stable disease. OS (604 vs 251 days), TTP (223 vs 87 days), and TTTF (363 vs 87 days) were all significantly longer for patients who had a partial response or stable disease (P < .05). Median OS, TTP, and TTTF for patients with colorectal carcinoma were 357, 112, and 107 days, respectively, versus 638, 118, and 363 days in patients with other metastatic sources. Median survival was not reached for patients with breast carcinoma, and the TTP and TTTF were each 282 days. One patient (3%) experienced grade 3 toxicity (gastrointestinal ulceration).

CONCLUSIONS

(90)Y microsphere therapy produced promising survival rates compared with systemic salvage options, with minimal toxicity.

Review article: panitumumab--a fully human anti-EGFR monoclonal antibody for treatment of metastatic colorectal cancer

BACKGROUND

Panitumumab is a fully human monoclonal IgG2 antibody targeting the epidermal growth factor receptor (EGFR).

AIM

To review the efficacy of panitumumab in the treatment of metastatic colorectal cancer (mCRC).

METHODS

Available literature identified from PubMed and conference websites was reviewed.

RESULTS

In phase 2-3 studies, panitumumab monotherapy achieved objective response rates (ORRs) of 8-13% in relapsed/refractory EGFR-expressing mCRC. In a randomized phase 3 study (463 patients), panitumumab almost halved the risk of disease progression/death vs. a control group receiving only best supportive care (hazard ratio 0.54; 95% CI: 0.44-0.66; P < 0.0001). Objective response was achieved in 22/231 (10%) patients randomized to panitumumab--and also in 20/176 (11%) patients assigned to the control group who received panitumumab in a separate crossover protocol after disease progression. Response was confined to patients with tumours harbouring wild-type KRAS (ORR approximately equal to 20%). Panitumumab is also being evaluated in earlier lines of treatment. Panitumumab monotherapy is generally well tolerated; the most common toxicities are skin toxicity (approximately equal to 90%) and diarrhoea (<30%). Development of anti-panitumumab antibodies (0.3% by ELISA) and grade 3-4 infusion reactions (<1%) are rare.

CONCLUSION

Panitumumab is an effective monotherapy option for patients with relapsed/refractory EGFR-expressing mCRC harbouring wild-type KRAS.

Immunotherapy for gastrointestinal cancer: current status and strategies for improving efficacy

BACKGROUND

Despite improvement in conventional strategies for treating gastrointestinal (GI) carcinoma, large numbers of patients still suffer from incurable or progressive disease.

OBJECTIVE

Here we consider the prospects for circumventing limitations and maximising the efficacy of different immunotherapies.

METHODS

We summarise different cancer vaccines and targeted drugs and highlight the scientific rationale of using immunotherapy for targeting GI cancers, in addition to the potential strategies for improving immunotherapeutic efficacy.

RESULTS/CONCLUSION

Many cancer vaccines and antibody-directed therapies have been tested in early phase clinical trials and demonstrated proof of concept and safety. As yet few have been properly evaluated for clinical efficacy; although adoptive transfer of tumour-associated-antigen-specific T cells has shown dramatic clinical responses in some patients. The recognition of a role for T regulatory cells in limiting anti-tumour immunity has provided momentum for developing strategies to over-ride such immunoinhibitory effects. There is some evidence that conventional therapies may work by influencing these negative factors and allowing expression of immune control mechanisms. An important developing area for clinical evaluation is the testing of combined conventional and immunotherapeutic modalities which may provide for synergy; thereby circumventing the limitations of individualised treatments and generating additional clinical benefits.

Systemic and targeted therapy for advanced colon cancer

Colorectal cancer (CRC) is the third most common malignancy and the second most common cause of cancer-related death in the USA. Prognosis is best when the disease is detected early; however, nearly two-thirds of newly diagnosed cases of CRC have lymph node involvement or metastatic disease. For years, 5-fluorouracil (FU)-based regimens represented the only viable treatment option for patients with metastatic CRC. However, in recent years several newer agents have been added to the treatment arsenal for this disease. These agents include oxaliplatin, irinotecan and newer monoclonal antibodies targeting the epidermal growth factor receptor (cetuximab and panitumumab) and VEGF (bevacizumab). This review aims to discuss current systemic and targeted therapies for metastatic colon cancer with a focus on mechanism of action, indications, toxicity and efficacy.

The multidisciplinary management of gastrointestinal cancer. The integration of cytotoxics and biologicals in the treatment of metastatic colorectal cancer

The management of patients with metastatic colorectal cancer (CRC) has changed dramatically over the last five years, with increasing chances of prolonged survival. The development of new drugs has contributed to the better outcome of patients with metastatic colorectal cancer. Until the mid-1990s the only available drug, with limited activity in metastatic CRC, was 5-fluorouracil (5-FU). The development of the cytotoxic agents irinotecan, oxaliplatin and capecitabine and of the monoclonal antibodies against the vascular endothelial growth factor (VEGF) bevacizumab and against the epidermal growth factor receptor (EGFR) cetuximab and panitumumab have clearly increased the therapeutic options and have improved the outcome for patients with metastatic colorectal cancer. However, their introduction also raises many new questions and challenges.

Association of progression-free survival with patient-reported outcomes and survival: results from a randomised phase 3 trial of panitumumab

In a randomised phase 3 trial, panitumumab significantly improved progression-free survival (PFS) in patients with refractory metastatic colorectal cancer (mCRC). This analysis characterises the association of PFS with CRC symptoms, health-related quality of life (HRQoL), and overall survival (OS). CRC symptoms (NCCN/FACT CRC symptom index, FCSI) and HRQoL (EQ-5D) were assessed for 207 panitumumab patients and 184 best supportive care (BSC) patients who had at least one post-baseline patient-reported outcome (PRO) assessment. Patients alive at week 8 were included in the PRO and OS analyses and categorised by their week 8 progression status as follows: no progressive disease (no PD; best response of at least stable disease) vs progressive disease (PD). Standard imputation methods were used to assign missing values. Significantly more patients were progression free at weeks 8–24 with panitumumab vs BSC. After excluding responders, a significant difference in PFS remained favouring panitumumab (HR=0.63, 95% CI=0.52–0.77; P<0.0001). At week 8, lack of disease progression was associated with significantly and clinically meaningful lower CRC symptomatology for both treatment groups and higher HRQoL for panitumumab patients only. Overall survival favoured no PD patients vs PD patients alive at week 8. Lack of disease progression was associated with better symptom control, HRQoL, and OS.

Epidermal growth factor receptor gene copy number and clinical outcome of metastatic colorectal cancer treated with panitumumab

PURPOSE

In a previous cohort study, we proposed that responsiveness of metastatic colorectal cancer (mCRC) to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies has a genetic basis, being associated with increased EGFR gene copy number (GCN) as measured by fluorescence in situ hybridization (FISH) in individual tumors. The present study was aimed at assessing the predictive role of EGFR GCN, in terms of clinical outcome, in patients treated with panitumumab.

PATIENTS AND METHODS

Patients with mCRC refractory to standard therapies were a subset of patients from a phase III trial of panitumumab plus best supportive care (BSC; n = 58) versus BSC alone (n = 34) who were selected on the basis of availability of tumor samples adequate for FISH.

RESULTS

In patients treated with panitumumab, a mean EGFR GCN of less than 2.5/nucleus or less than 40% of tumor cells displaying chromosome 7 polysomy within the tumor predicted for shorter progression-free survival (PFS; P = .039 and P = .029, respectively) and overall survival (P = .015 and P = .014, respectively). None of the treated patients with mean EGFR GCN of less than 2.47/nucleus or less than 43% of tumor cells displaying chromosome 7 polysomy obtained objective response compared with six of 20 and six of 19 patients with values greater than these cutoff limits, respectively (P = .0009 and P = .0007, respectively). Evaluation of BSC-treated patients showed no correlation between EGFR GCN or chromosome 7 polysomy status and PFS.

CONCLUSION

In a larger and more homogeneous series than in previous studies, present exploratory data suggest that mCRC patients with tumors distinguishable by FISH analysis of EGFR as homogenously disomic or with low chromosome 7 polysomy have a reduced likelihood of response to panitumumab.