Transcatheter arterial infusion of anti-programmed cell death 1 antibody pembrolizumab combined with temozolomide or nab-paclitaxel in patient with primary anorectal malignant melanoma

Primary anorectal malignant melanoma (ARMM) is an extremely rare but aggressive tumor. We assessed the efficacy and safety of transcatheter arterial infusion (TAI) with anti-PD-1 antibody pembrolizumab at a dosage of 100 mg with 0.9% NaCl at a volume of 100 mL administered over a 30-min period every 3 weeks, combined with temozolomide or albumin-bound paclitaxel (nab-paclitaxel) in four patients with ARMM. Temozolomide was administered orally once per day at a dosage of 200 mg/m2/d for five consecutive days about every 4 weeks. Nab-paclitaxel was administered at a dosage of 200mg/m2/d once about every 3 weeks. Among four patients with a median follow-up of 8.9 months, two cases showed Murine Double Minute 2 (MDM2) amplification. Case 1 with Stage II ARMM showed pathological complete response after four cycles of TAI with pembrolizumab combined with nab-paclitaxel. Case 4 was at Stage II and showed stable disease consistently throughout the treatment. Case 2 was at stage II and Case 3 was at stage III, and they showed partial response after four or three cycles, respectively, of TAI with pembrolizumab combined with temozolomide. No Grades 3–4 adverse reactions were observed. Therefore, a combination of TAI with pembrolizumab and temozolomide or with nab-paclitaxel appears to be a promising option for treating ARMM. However, multicenter clinical trials are required to confirm the efficacy and safety of this procedure.