Among patients with colorectal cancer, skin treatment beginning on the day prior to therapy with Vectibix® (panitumumab) significantly reduces skin side effects associated with Vectibix compared with skin treatment after side effects occur. These results were presented at the 10th World Congress on Gastrointestinal Cancer held in Spain in June 2008.

Colon cancer remains the second leading cause of cancer-related deaths in the United States. Patients who have already received therapy and experience disease progression or a recurrence following standard therapies have limited treatment options. Vectibix is a new targeted therapy that binds to specific targets on cancer cells. Vectibix targets the epidermal growth factor receptor (EGFR), a biologic pathway that is involved in the growth and spread of cancer. By targeting EGFR, Vectibix can destroy cancer cells directly while sparing healthy cells from the side effects of treatment. Vectibix, which is FDA approved, is often used in combination with chemotherapy for the treatment of colorectal cancer.

The main side effects associated with Vectibix are skin reactions. These reactions can be mild to severe and often adversely affect a patient’s quality of life. Researchers have been evaluating ways to minimize these side effects.

Researchers from several institutions in the United States recently conducted a trial, referred to as the STEPP trial, which compared two different approaches aimed at minimizing skin reactions associated with treatment with Vectibix. This trial included nearly 100 patients with advanced, recurrent colorectal cancer who were treated with Vectibix plus a Camptosar® (irinotecan)-based chemotherapy regimen. Patients were divided into two groups: one group received preemptive skin treatment, which started the day before beginning therapy and continued through the sixth week of therapy, while the other group received reactive treatment, which was administered anytime during the six weeks of therapy if the healthcare provider felt that side effects of the skin necessitated therapy. Skin treatment included skin moisturizer (applied to the entire body, except stomach and legs, every morning), sunscreen (applied to exposed skin areas prior to being outdoors), topical steroid (applied to entire body, except stomach and legs, at bedtime), and the antibiotic doxycycline. Upon the seventh week of treatment, patients had the option to continue skin treatment.

• Only 29% of patients experienced serious skin reactions in the preemptive group compared with 62% in the reactive treatment group.
• The effectiveness of Vectibix/chemotherapy was not affected by preemptive skin therapy.
• Median progression-free survival was 4.9 months for patients in the pre-emptive skin therapy group and 4.3% for patients in the reactive skin therapy group.
• Median overall survival was approximately 13.5 months for both groups of patients.
• As with other EGFR inhibitors, patients without KRAS mutations had improved outcomes compared with those who had KRAS mutations.

The researchers concluded that preemptive therapy for skin reactions appears to significantly reduce the rate of skin reactions associated with treatment with Vectibix among colorectal cancer patients without affecting the therapy’s effectiveness.

Comments: These maneuvers appear to alleviate the side effects of Vectibix.

Reference: Mitchell E, LaCouture M, Shearer H, et al. Updated Results of STEPP, a Phase 2, Open-Label Study of Pre-Emptive Versus Reactive Skin Toxicity Treatment in Metastatic Colorectal Cancer (mCRC) Patients Receiving Panitumumab + FOLFIRI or Irinotecan-Only Chemotherapy as Second-Line Treatment. 10th World Congress on Gastrointestinal Cancer. June 2008. Barcelona, Spain.

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Vectibix™ (Panitumumab) Approved for Recurrent Colorectal Cancer (09/29/2006)