INTRODUCTION: Recent approval and introduction into clinical practice of epidermal growth factor receptor inhibitors such as the chimeric monoclonal antibody cetuximab and the fully human monoclonal antibody panitumumab have provided new treatment options for chemotherapy-refractory patients. Here, we report a case of a 47-year-old man with metastatic, chemotherapy-refractory colorectal cancer who achieved long-term partial remission during panitumumab therapy.
CASE PRESENTATION: A 41-year-old male patient presented with a 24-hour history of abdominal pain and fever. A computed tomography (CT) scan revealed a voluminous and perforated abscess with a suspected tumour lesion in the sigmoid colon. The patient underwent sigmoidectomy and was diagnosed with a poorly differentiated necrotic carcinoma of the sigmoid colon with invasion in 13 of 19 tested lymph nodes. A colonoscopy revealed multiple tubular adenomas and a positron emission tomography CT scan showed multiple and bilateral hyperfixating lumbar-aortic lymph nodes leading to a final tumour classification of T4N2M1. Carcinoembryonic antigen (CEA) was elevated. The patient achieved a partial response following six cycles of FOLFIRI (irinotecan, 5-fluorouracil, leucovorin), then progressed and was enrolled in a trial where he received treatment with FOLFOX4 (oxaliplatin, leucovorin and 5-fluorouracil) with or without a vascular endothelial growth factor inhibitor (PTK787/ZK 222584 [valatinib]). Eight months later he progressed again and was included in a panitumumab (6mg/kg every 2 weeks) monotherapy trial. A partial response was noted after 8 weeks of therapy along with a rapid CEA reduction and decrease in lymph node size. The patient is continuing panitumumab treatment and is still in partial remission after 65 months' treatment. He has non-mutated KRAS and no human-anti-human antibodies have been detected. During treatment the patient has on occasion experienced grade 1-2 diarrhoea as well as folliculitis and acne-like rash up to grade 3 in severity. Cutaneous toxicity was managed with a combination dose interruption/reduction and the use of topical agents. No eye or nail toxicities occurred.
CONCLUSION: This case shows that long-term responses are possible during panitumumab therapy and that this agent may be an effective long-term treatment option for selected patients with metastatic colorectal cancer. The associated skin toxicities can be successfully managed.