Natural Agents-Mediated Targeting of Histone Deacetylases.

In the past few years, basic and clinical scientists have witnessed landmark achievements in many research projects, such as those conducted by the US National Institutes of Health Roadmap Epigenomics Mapping Consortium, the International Human Epigenome Consortium, The Cancer Genome Atlas Network and the International Cancer Genome Consortium, which have provided near-complete resolution of epigenetic landscape in different diseases. Furthermore, genome sequencing of tumors has provided compelling evidence related to frequent existence of mutations in readers, erasers and writers of epigenome in different cancers. Histone acetylation is an intricate mechanism modulated by two opposing sets of enzymes and deeply studied as a key biological phenomenon in 1964 by Vincent Allfrey and colleagues. The research group suggested that this protein modification contributed substantially in transcriptional regulation. Subsequently, histone deacetylases (HDACs), histone acetyltransferases and acetyl-Lys-binding proteins were identified as transcriptional mediators, which further deepened our comprehension regarding biochemical modifications. Overwhelmingly increasing high-impact research is improving our understanding of this molecularly controlled mechanism; moreover, quantification and identification of lysine acetylation by mass spectrometry has added new layers of information. We partition this multi-component review into how both activity and expression of HDAC are targeted using natural agents. We also set spotlight on how oncogenic fusion proteins tactfully utilize HDAC-associated nano-machinery to modulate expression of different genes and how HDAC inhibitors regulate TRAIL-induced apoptosis in cancer cells. HDAC inhibitors have been reported to upregulate expression of TRAIL receptors and protect TRAIL from proteasomal degradation. Deeper understanding of HDAC biology will be useful for stratification and selection of patients who are responders, non-responders and poor-responders for HDACi therapy, and for the rational design of combination studies using HDACi.

Phase II study of capecitabine plus cisplatin in patients with gastric cancer.

A phase II study was conducted to assess the efficacy and toxicity of combination therapy with capecitabine and cisplatin in patients with de-novo advanced gastric cancer, and in patients with refractory/recurrent gastric cancer after previous nonplatinum-based therapy. Sixty-four patients were enrolled in the study. Of these, 50 patients had untreated gastric cancer, and 14 had received previous therapy with nonplatinum-based therapy. All patients received oral capecitabine 1250 mg/m2 twice daily, days 1-14, and intravenous cisplatin 60 mg/m2 on day 1. This cycle was repeated every 3 weeks. Among the 50 previously untreated patients, three achieved complete response, and 19 had partial response, giving a response rate of 44% in the intention-to-treat population. The median time to progression and median overall survival were 6 months [95% confidence interval (CI): 1.4-10.6] and 9 months (95% CI: 5.7-12.3), respectively. In patients who had received previous therapy, clinical usefulness was evaluated resulting in response rate of 14%, disease control rate of 28.5%, and median overall survival of 4 months (95% CI: 3.1-4.9). The principal grade 3/4 adverse events were neutropenia (20%), anemia (14%). No neutropenic fever or treatment-related deaths. Capecitabine in combination with cisplatin is effective and well tolerated as first-line treatment in patients with advanced gastric cancer. Unfortunately, we could not positively suggest the usefulness of the same combination regimen as salvage therapy in patients with progressive or recurrent disease after nonplatinum-based therapy.