DIHYDROPYRIMIDINE DEHYDROGENASE DEFICIENCY (DPD) IN GI MALIGNANCIES: EXPERIENCE OF 4-YEARS

ABSTRACT Objectives: 5-Fluorouracil (5-FU) is an integral part of treatment of GI malignancies. While normal DPD enzyme activity is rate limiting in 5-FU catabolism, its deficiency could increase concentrations of bioavailable 5-FU anabolic products leading to 5-FU related toxicity syndrome. Methodology: Twenty-three patients were tested for DPD deficiency after excessive toxicities from 5-FU and/or capecitabine. DPD activity was evaluated by Peripheral Blood Mononuclear Cell (PBMC) radioassay, genotyping of DPYD gene by Denaturing High Performance Liquid Chromatography (DHPLC), or 2-13 C uracil breath test (UraBT). Results: Of 23 patients with excessive toxicities from 5-FU and/or capecitabine, 7 (30%) were DPD deficient with a median age of 66 years, M:F ratio = 1.3:1 and ethnicities included Caucasian (71%), African-American (14%) and South-Asian (14%). DPD activity ranged from 0.064 -0.18nmol/ min/mg. Three patients were treated with bolus 5-FU/LV, two with capecitabine, and two with high dose bolus 5-FU with 2', 3', 5'-tri-O-acetyluridine. Toxicities included mucositis (71%), diarrhea (43%), skin rash (43%), memory loss/altered mental status (43%), cytopenias (43%), nausea (29%), hypotension (14%), respiratory distress (14%) and acute renal failure (14%) Re-challenge with capecitabine in one patient after the Mayo regimen caused grade 3 hand-foot syndrome. Genotypic analysis of the DPYD gene in one patient with severe leucopenia demonstrated a heterozygous mutation (IVS14+1 G>A, DPYD). The UraBT in two patients revealed 1 to be DPD-deficient (DOB 50 of 112.8; PDR of 49.4%) and borderline normal values (DOB 50 of 130.9; PDR of 52.5%) in a second patient. There were 2 toxicity-related deaths among DPD-deficient patients (28%). Conclusions: DPD deficiency was observed in several ethnicities. Akin to 5-FU, capecitabine can also lead to severe toxicities in DPD-deficient patients. Screening patients for DPD deficiency prior to administration of 5-FU or capecitabine using UraBT could potentially lower risk of toxicity. Future studies should validate this technique

TAS-102 an emerging oral fluoropyrimidine

Colon cancer is a common type of cancer with high mortality. The standard therapy for colon cancer is 5-FU-based regimen, although the current response rate to 5-FU is only 10-15%. Various approaches have been used to improve the efficacy of 5-FU including inhibition of its degradation enzyme dihydropyrimidine dehydrogenase (DPD) such as S1, UTF, use of 5-FU pro-drug capecitabine to exploit thymidine phosphorylase (TP) and supplementation of reduced folate acid to increase cytotoxicity. TAS-102 is a newly-developed anti-folate drug containing the 5-FU analogue trifluridine (TFD) and tipiracil hydrochloride (TPI). TPI is an inhibitor of TFD degradation enzyme thymidine phosphorylase and thus increases the bioavailability of TFD. In the present review, we summarize recent progress with regard to TAS-102, including pre-clinical tests and clinical trials. We further propose several approaches to further improve the efficacy of TAS-102 including combination with targeted therapy and immune therapy

Heat shock protein inhibitors and vaccines as new agents in cancer treatment

Background: Heat shock proteins (HSP) play an essential role as molecular chaperones by assisting correct holding and folding in human cells. At the same time they present implications in tumor cell proliferation, differentiation, matrix invasion, angiogenesis, metastasis and cell death. They also possess the ability to present tumor molecules to the immune system and elicit an immune response. New agents targeting HSP, as anticancer treatment, are under clinical evaluation. Objective: The aim of this review is to explore the role of HSP90 inhibitors as anticancer agents as well as to evaluate the benefit from the use of autologous HSP vaccines in both the adjuvant setting and first-line treatment. Methods: The latest evidence regarding the use of geldanamycin analogues or newer water-soluble and synthetics molecules that inhibit the binding of HSP90 to client proteins was reviewed. Immunization using tumor-derived HSP in several cancer types was also evaluated. Conclusions: HSP90 inhibitors represent a promising therapeutic option although further evaluation in larger clinical trials is needed. On the other hand, HSP vaccination has already an established role in our armory against cancer

Association between Rash and a Positive Drug Response Associated with Vinorelbine in a Patient with Primary Peritoneal Carcinoma

Vinorelbine (Navelbine, VRL) is commonly used for platinum-resistant ovarian cancer and has been shown to be effective in patients with recurrent primary peritoneal carcinoma. Of VRL’s major side effects, skin rash is uncommon, and, if it does occur, it is usually localized to site of injection. In this case report, a 71-year-old Hispanic female with primary peritoneal carcinoma received single agent VRL as fourth-line regimen, which she tolerated very well except for a skin rash related to VRL. The rash continued to progress throughout 6 cycles of VRL, and follow-up CT/PET scan demonstrated complete metabolic and radiological responses. We, therefore, believe that this rash was linked to VRL administration and correlated with response to therapy. Rash has been recognized as a useful surrogate marker with targeted agents such as cetuximab and erlotinib; to the best of our knowledge, this case report describes the first patient with a possible drug rash and its association with a positive outcome. This case report incites interest in further investigation of similar cases to support this observation, since there is a lack of reports of skin rash with VRL therapy