The relationship between the expression of thymidylate synthase, dihydropyrimidine dehydrogenase, orotate phosphoribosyltransferase, excision repair cross-complementation group 1 and class III β-tubulin, and the therapeutic effect of S-1 or carboplatin plus paclitaxel in non-small-cell lung cancer

Role of pH in Regulating Cancer Pyrimidine Synthesis

Replication is a fundamental aspect of cancer, and replication is about reproducing all the elements and structures that form a cell. Among them are DNA, RNA, enzymes, and coenzymes. All the DNA is doubled during each S (synthesis) cell cycle phase. This means that six billion nucleic acids must be synthesized in each cycle. Tumor growth, proliferation, and mutations all depend on this synthesis. Cancer cells require a constant supply of nucleotides and other macromolecules. For this reason, they must stimulate de novo nucleotide synthesis to support nucleic acid provision. When deregulated, de novo nucleic acid synthesis is controlled by oncogenes and tumor suppressor genes that enable increased synthesis and cell proliferation. Furthermore, cell duplication must be achieved swiftly (in a few hours) and in the midst of a nutrient-depleted and hypoxic environment. This also means that the enzymes participating in nucleic acid synthesis must work efficiently. pH is a critical factor in enzymatic efficiency and speed. This review will show that the enzymatic machinery working in nucleic acid synthesis requires a pH on the alkaline side in most cases. This coincides with many other pro-tumoral factors, such as the glycolytic phenotype, benefiting from an increased intracellular pH. An increased intracellular pH is a perfect milieu for high de novo nucleic acid production through optimal enzymatic performance.

Anlotinib Combined with S-1 in the Third-Line Treatment of Stage IV Non-Small Cell Lung Cancer: Study Protocol for Phase II Clinical Trial

Background:

A proportion of patients with stage IV non-small-cell lung cancer (NSCLC) is predicted to receive third-line treatment. However, currently no standard third-line treatment for NSCLC is available. Anlotinib is an oral, multi-targeted tyrosine kinase (TK) receptor inhibitor, which was approved as a third-line treatment for stage IV NSCLC in China on May 9, 2018. Nevertheless, The objective response rate of patients treated with anlotinib was merely 9.2% and the overall survival was only 3 months compared with the patients treated with placebo. Previous studies have shown that cancer treatment with a combination of chemotherapy with TK receptor inhibitors is effective and safe well tolerated. Therefore, the combination of anlotinib with other chemotherapeutic agents may be an effective treatment strategy for patients with stage IV NSCLC. Oral S-1 is a third-generation fluorouracil derivative; it showed good efficacy and caused relatively low toxicity in patients with NSCLC.

Methods:

The purpose of this trial is to evaluate the efficacy and safety of anlotinib combined with S-1 as the third-line treatment for patients with stage IV NSCLC. This is a prospective, phase II clinical trial. We will enroll29 patients with stage IV NSCLC treated with anlotinib plus S-1. Tumors will be assessed using computed tomography prior to treatment, after two, four, and six cycles of treatment, and during follow-up every 3 months until disease progression or death. The primary endpoint is the objective response rate (ORR). The secondary endpoints are progression-free survival, duration of response, proportion of disease control, and safety.

Discussion:

The expected outcome of this study is that anlotinib combined with S-1 has tolerable toxicity and better ORR than anlotinibmonotherapy. The results may indicate additional treatment options for patients with stage IV NSCLC.

Tailored therapy in patients treated with fluoropyrimidines: focus on the role of dihydropyrimidine dehydrogenase

Fluoropyrimidines are widely used in the treatment of solid tumors, mainly gastrointestinal, head and neck and breast cancer. Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme for catabolism of 5-FU and it is encoded by DPYD gene. To date, many known polymorphisms cause DPD deficiency and subsequent increase of 5-FU toxicity. In addition, reduced inactivation of 5-FU could lead to increased 5-FU intracellular concentration and augmented efficacy of this drugs. Therefore DPD expression, particularly intratumoral, has been investigated as predictive and prognostic marker in 5-FU treated patients. There also seems to be a tendency to support the correlation between DPD expression and response/survival in patients treated with fluoropyrimidine even if definitive conclusions cannot be drawn considering that some studies are conflicting. Therefore, the debate on intratumoral DPD expression as a potential predictor and prognostic marker in patients treated with fluoropyrimidines is still open. Four DPD-polymorphisms are the most relevant for their frequency in population and clinical relevance. Many studies demonstrate that treating a carrier of one of these polymorphisms with a full dose of fluoropyrimidine can expose patient to a severe, even life-threatening, toxicity. Severe toxicity is reduced if this kind of patients received a dose-adjustment after being genotyped. CPIC (Clinical Pharmacogenetics Implementation Consortium) is an International Consortium creating guidelines for facilitating use of pharmacogenetic tests for patient care and helps clinicians ensuring a safer drug delivery to the patient. Using predictive DPD deficiency tests in patients receiving 5FU-based chemotherapy, in particular for colorectal cancer, has proven to be a cost-effective strategy.