When side effect becomes the effect: Efficacy of capecitabine in refractory psoriasis

Dear Editor, Psoriasis vulgaris (PV) is one of the most common chronic inflammatory skin disorders characterized by hyperproliferation of epidermal keratinocytes. PV substantially affects the quality of life and is associated with disfigurement, and disability (Boehncke & Schon, 2015). Topical agents remain to be the cornerstone of treatment in mild disease. Phototherapy and systemic therapies such as methotrexate, cyclosporine, acitretin are the conventional systemic therapies. Biologic drugs including tumor necrosis factoralfa antagonists, anti-Interleukin (IL)12/23, and anti-IL17 provide a more specific treatment and are indicated for patients who have a resistant disease (Boehncke & Schon, 2015; Kelly, Foley, & Strober, 2015; Kunz, 2009). Here, we present the first case of a psoriatic patient with metastatic gastric cancer whose lesions regressed significantly after capecitabine (Xeloda; Roche Medical) treatment. A 59-year old male presented to our center with newly diagnosed metastatic gastric cancer. He had a history of plaque-type psoriasis for 19 years. He had been treated with infliximab for the last 8 years with complete clinical response. After the diagnosis of gastric cancer, infliximab treatment was terminated, the patient was under follow-up with topical emollients. Of note, in this patient long-term inhibition of tumor necrosis factor alfa may have a role in inducing and evolution of cancer. Docetaxel, cisplatin, and 5-fluorouracil (5-FU) (DCF treatment) was commenced. While he received DCF chemotherapy, 8 mg dexamethasone was administered as a precaution for docetaxel anaphylaxis on the first day of the infusion and no any topical agent was applied for psoriasis during the whole chemotherapy period. He had no psoriatic lesions throughout the treatment period, but the exacerbation of PV was observed after termination of the DCF treatment. After DCF treatment, single-agent capecitabine (1,250 mg/m bid for 14 days, every 3 weeks) treatment was started for gastric cancer. At the beginning of the first cycle of capecitabine, psoriatic lesions were highly active with widespread erythematous scaly plaques involving 70% of the body surface area (Figure 1). At the end of the first cycle, skin lesions of the patient improved significantly (Figure 2). This effect continued in subsequent cycles and capecitabine was well-tolerated. 5-FU is an antimetabolite like methotrexate which is a widely used systemic agent for PV. They are both active at S phase of cell cycle. They are cycle specific and affect mostly rapidly proliferating cells (Parker, 2009). 5-FU interferes with DNA synthesis as well as RNA processing and therefore decreases epidermal proliferation (Ceilley, 2012). It has been used topically or intralesionally for treatment for psoriatic nails. The oral preparation of 5-FU, conversely, has not been used in clinical practice because of unpredictable absorption. 5-FU infusion in a cancer patient which resulted in subsequent erosions and necrosis over the psoriasis plaques similar to methotrexate intoxication is an example to this concern (Wetzig, Beckheinrich, Rytter, & Haustein, 2002).