Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the efficacy and safety of panitumumab versus cetuximab as seen in the ASPECCT trial in colorectal cancer (CRC).

The ASPECCT trial examined panitumumab and cetixumab in chemotherapy-resistant patients with colorectal cancer. Peeters says the trial found that there is no difference in progression-free survival or overall response between the two agents. However, the study did show there are some differences in toxicity.

Hypomagnesemia is more commonly seen in patients treated with panitumumab while there are more infusion reactions seen in patients treated with cetixumab, Peeters says. However, the occurrence and severity of skin toxicities seems to be very similar between the two agents.

Peeters says from an efficacy standpoint, the two agents are similar but the mild differences in toxicity seen between the two agents may play a role in the decision-making process of each patient.

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Dr. Peeters Discusses the Efficacy and Safety of Panitumumab Versus Cetuximab in CRC

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the frequency of 

 mutations found in patients with metastatic colorectal cancer who were treated with panitumumab or cetuximab monotherapy.

For this analysis, tumor samples from the phase III ASPECCT trial were analyzed to find the specific point mutation of 

 in the EGFR receptor region, Peeters notes. In ASPECCT, the EGFR inhibitors panitumumab and cetuximab were compared as treatments for patients with chemorefractory wild-type KRAS metastatic colorectal cancer.

Researchers compared baseline results to tumor samples that were taken 4 weeks after treatment was stopped, in order to ascertain whether the mutation is due to induction of resistance or if it was already present at baseline, Peeter notes.

 mutations were not detected in either arm. However, following treatment, 16% of patients that were treated with cetuximab tested positive for the mutation compared with less than 5% in the panitumumab arm.

These findings highlight the differences between the two EGFR inhibitors. This analysis provides new insight for treatment strategies, Peeters believes, since patients who develop the 

 mutation following induction therapy with cetuximab could potentially still be candidates for treatment with panitumumab.

View more from the 2014 World GI Congress

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the frequency of S492R mutations found in patients with metastatic colorectal cancer patients who were treated with panitumumab or cetuximab monotherapy.

Dr. Peeters on the Frequency of S492R Mutations Following EGFR Inhibition in mCRC

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the future of the treatment of colorectal cancer.

Peeters says in the future, patients with colorectcal cancer will continue to receive treatment in a multidisciplinary setting. In addition to medical oncologists making decisions, surgeons, radiation oncologists, and gastroenterologists will be part of the team to decide on strategies for patients.

Peeters says colorectal cancer treatment needs to remain personalized.

For the field to advance, new drugs must be developed, Peeters says. Currently, patients with colorectal cancer are living longer and asking for newer options to prolong survival. Peeters says colorectal cancer is moving towards becoming a chronic disease, where the help of multidisciplinary teams and newer agents are needed.

Dr. Peeters on the Future of Colorectal Cancer

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses an analysis of 

 mutations in the phase III study 20050181, which compared panitumumab plus FOLFIRI versus FOLFIRI for second-line treatment of metastatic colorectal cancer (mCRC).

Peeters says before patients with mCRC are treated with anti-EGFR agents, they are tested for 

 exon 2 status of their tumor. If the patient has a mutated tumor, they are not treated with anti-EGFR agents such as panitumumab or cetuximab.

In an analysis of the phase III study 20050181, researchers first looked for the wild-type patients in 

 exon 2 and then looked at the exon 3 and exon 4 in the 

 genes, Peeters says. The analysis showed an additional 18% of new mutations outside the 

 exon 2 gene. Further analysis showed that if a patient has a mutated tumor, there is no benefit but there is also no harm when a patient is treated with panitumumab plus FOLFIRI. If patients have a wild-type 

 tumor, the analysis showed that there is a clear benefit in progression-free survival and overall survival when panitumumab is combined with FOLFIRI, Peeters says.

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses an analysis of RAS mutations in the phase III study 20050181, which compared panitumumab plus FOLFIRI versus FOLFIRI for second-line treatment of mCRC

Dr. Peeters on KRAS/NRAS Mutations in mCRC

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the utility of aflibercept in patients with advanced colorectal cancer.

Based on available data, there are two populations where aflibercept could be used. The first group, consisting of patients who rapidly progress on bevacizumab, may benefit from another VEGF-targeting agent. The second subgroup of patients consists of those who could see a better response in the second line, Peeters says.

Previous data demonstrates that it is crucial to directly impact the disease as it evolves quickly, Peeters says. It is also important to induce a response in patients and move to resection in the second-line setting.

Dr. Peeters on the Utility of Aflibercept in CRC

Marc Peeters, MD, PhD, department of oncology, Antwerp University Hospital, Antwerpen, Belgium, discusses the importance of properly managing the toxicities associated with aflibercept when treating patients with metastatic colorectal cancer.

There is an impression that treatment with aflibercept is associated with more toxicity than bevacizumab, based on findings from the VELOUR trial. However, Peeters believes, when examining findings from clinical practice and cohort studies it seems clear that aflibercept-related side effects can be managed without altering dose intensity or schedule. As a result, familiarity with managing drug-related toxicity is important, to optimize treatment.

Marc Peeters, MD, PhD, from the Antwerp University Hospital, discusses the importance of properly managing the toxicities associated with aflibercept when treating patients with metastatic colorectal cancer.

Marc Peeters, MD, PhD

Articles

Dr. Peeters Discusses the Efficacy and Safety of Panitumumab Versus Cetuximab in CRC

Dr. Peeters on the Frequency of S492R Mutations Following EGFR Inhibition in mCRC

Dr. Peeters on the Future of Colorectal Cancer

Dr. Peeters on KRAS/NRAS Mutations in mCRC

Dr. Peeters on the Utility of Aflibercept in CRC

Dr. Marc Peeters on the Aflibercept Toxicity Profile