Bevacizumab-based therapies in the first-line treatment of metastatic colorectal cancer

Alternate dosing of cetuximab for patients with metastatic colorectal cancer

BACKGROUND

Many chemotherapeutic regimens used to treat colorectal cancer (CRC), including 5-fluorouracil plus leucovorin in combination with irinotecan (FOLFIRI) or oxaliplatin (FOLFOX), are administered on an every-other-week (q2w) dosing schedule. Chemotherapy in combination with a monoclonal antibody (mAb) directed toward the epidermal growth factor receptor (EGFR) has emerged as an effective treatment option. There are currently 2 anti-EGFR mAbs approved by the United States Food and Drug Administration: cetuximab and panitumumab. Mutations of KRAS, a downstream protein in the EGFR pathway, predict resistance to EGFR mAbs. Thus, cetuximab and panitumumab are indicated for patients without a KRAS mutation (KRAS wild-type). Whereas panitumumab is approved on a q2w dosing schedule, cetuximab is approved as a weekly dose. However, only cetuximab is approved with FOLFIRI for frontline metastatic CRC, whereas panitumumab is approved for third-line. Because concomitant therapies are often administered q2w, the weekly dosing of cetuximab results in additional medical office visits.

DESIGN

Several studies have assessed the safety and efficacy of cetuximab q2w. For this review, a comprehensive literature search of studies evaluating cetuximab q2w dosing was conducted. Safety and efficacy results of these trials and retrospective analyses were summarized and reviewed.

RESULTS

In general, results with cetuximab q2w were comparable to those obtained with the weekly regimen.

CONCLUSION

These data suggest that for patients for whom weekly treatment with cetuximab presents a substantial burden to their quality of life, q2w dosing of cetuximab is a viable treatment option with a benefit:risk profile similar to that of the weekly regimen.

Current and Novel Treatment Options for Metastatic Colorectal Cancer: Emphasis on Aflibercept

Worldwide, colorectal cancer (CRC) is the third most frequently diagnosed cancer in men and the second in women. Metastatic disease develops in more than half of the patients and carries a poor prognosis. Over the past three decades, significant advances have been made in the treatment of metastatic colorectal cancer (mCRC). The development of new cytotoxic agents and the incorporation of target-specific agents in first-, second-, third-, and nowadays even fourth-line treatment has prolonged median overall survival up to 24–28 months. However, 5-year survival rates remain disappointingly low. This review summarizes the currently available cytotoxic treatment options for mCRC, and highlights the further emerging role of vascular endothelial growth factor (VEGF)-inhibiting strategies, emphasizing the role of aflibercept. Aflibercept is a recombinant fusion protein with high VEGF affinity, and is the second antiangiogenic agent to obtain registration in the treatment of mCRC.

Controlling escape from angiogenesis inhibitors

Selective inhibition of vascular endothelial growth factor (VEGF) increases the efficacy of chemotherapy and has beneficial effects on multiple advanced cancers, but response is often limited and the disease eventually progresses. Changes in the tumour microenvironment--hypoxia among them--that result from vascular pruning, suppressed angiogenesis and other consequences of VEGF inhibition can promote escape and tumour progression. New therapeutic approaches that target pathways that are involved in the escape mechanisms add the benefits of blocking tumour progression to those of slowing tumour growth by inhibiting angiogenesis.