China
Africa
Explore chapters and articles related to this topic
Total Body Irradiation
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
The American College of Radiology/American Society for Radiation Oncology (ACR-ASTRO) Practice Parameter (ACR 2017) identifies a number of advantages of TBI as part of conditioning for bone marrow transplants: A homogeneous dose is delivered to the whole body (with the option to spare particular organs as required) independently of the blood supply to a particular area. In consequence, there are no sanctuary sites.The dose can be precisely controlled and is not subject to physiological influences.There is less likelihood of cross-resistance with other chemotherapeutic agents.
Clinical Implications of the Phenomenon of Drug Resistance
Published in Nicholas Bruchovsky, James H. Goldie, Drug and Hormone Resistance in Neoplasia, 2019
Providing one keeps in mind what the objectives are in combination chemotherapy, it should be possible to design appropriate and rational drug treatment sequences whose exact form will be dictated by the number and variety of agents available. Because it appears that the requirement for complete lack of cross-resistance can be significantly relaxed, then protocol design which involves the retention of the most active of a series of agents in each treatment block is entirely feasible. Likewise there need be no concern about the continuous application of essentially nontoxic agents such as steroid hormones to the chemotherapy. Although contributing to “cross-resistance”, the quantitative effect of these additional agents will more than counterbalance this effect.
Mechanisms of Resistance to Antineoplastic Drugs
Published in Robert I. Glazer, Developments in Cancer Chemotherapy, 2019
Philip J. Vickers, Alan J. Townsend, Kenneth H. Cowan
Cellular resistance to antineoplastic drugs can be classified into a number of different types, as shown in Table 1. In considering these mechanisms, it should be remembered that members of the same class of drug may share common transport processes, metabolism, and site of action. Because drug resistance may be due to alterations in one or more of these parameters, the cells which develop resistance to a particular drug will frequently be cross-resistant to other members of the same class of drug. However, this will generally not affect the sensitivity of the cells to other classes of cytotoxic drugs. For example, there are several different mechanisms whereby cells may develop resistance to the antifolate methotrexate (4-deoxy-4-amino-10-methyl folate, MTX). While MTX-resistant cells may be resistant to other antifolates, in general antifolate-resistant cells are not cross-resistance to anthracy-clines.4 Likewise, resistance to one alkylating agent may lead to cross-resistance to other agents in this class, but does not in general result in cross-resistance to other classes of antitumor agents.5 The exception to this dogma is the phenomenon of pleiotropic or “multidrug” resistance (MDR). In this phenotype, cells selected for resistance to one agent develop cross-resistance to a wide range of agents which differ markedly in structure and apparent mechanism of action. Because of the clinical implications of and growing interest in this phenomenon, the mechanisms associated with the development of MDR will be considered in some detail later in this review.
Emerging peptide therapeutics for the treatment of ovarian cancer
Published in Expert Opinion on Emerging Drugs, 2023
Ana C. Veneziani, Eduardo Gonzalez-Ochoa, Amit M. Oza
Primary or acquired treatment resistance has been a major clinical challenge, and subsequent treatment options are limited, leading to broad cross-resistance. For example, in platinum-resistant EOC, response rates to single-agent chemotherapy are as low as 10–15%, and median overall survival (OS) is estimated at only 12 months [8]. Hence, there is an urgent need to identify novel therapeutic approaches, which may be effective in this setting for EOC. Proteomic technologies, such as mass spectrometry and protein array analysis, have significantly advanced our ability to understand molecular signaling events and proteomic profiles [23]. Proteomic analysis of ovarian cancer and its adaptive responses to therapy can reveal new therapeutic options that have the potential to mitigate drug resistance and improve patient outcomes.
Novel avenues for identification of new antifungal drugs and current challenges
Published in Expert Opinion on Drug Discovery, 2022
Superficial mycoses are most often caused by filamentous fungi (e.g. genera Trichophyton, Epidermophyton, and Microsporum) and yeasts of genera Candida (C. albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis) and Malassezia furfur. In the last decade, they have shown high resistance to fluconazole, voriconazole, and echinocandins. Invasive fungal infections are caused by Candida, Aspergillus, Fusarium, Cryptococcus, and Pneumocystis. Increasing resistance, cross-resistance, and the occurrence of multidrug-resistant or completely resistant strains are evident in all of these genera. New pathogenic strains such as Candida auris or Emergomyces sp. have also been reported [6,8,16–21].
The role of UDP-glycosyltransferases in xenobioticresistance
Published in Drug Metabolism Reviews, 2022
Diana Dimunová, Petra Matoušková, Radka Podlipná, Iva Boušová, Lenka Skálová
Some UGTs detoxify insecticides with different chemical structures and could thus be responsible for cross-resistance and/or multi-resistance in insect species, e.g. four Spodoptera UGT genes were significantly co-upregulated by the insecticides lambda-cyhalothrin, chlorantraniliprole, metaflumizone, and indoxacarb (Hu, Hu, et al. 2019). Chen et al. (2019) tested the involvement of two UGTs (UGT344B4 and UGT344C7) previously identified as having higher expression in resistant field populations of A. gossyppi, an aphid with resistance to multiple insecticides. Various types of cross-resistance were confirmed, e.g. cross-resistance to sulfoxaflor was detected in a field-originated imidacloprid-resistant population (Chen et al. 2019). Furthermore, the involvement of specific UGT(s) in resistance to multiple insecticides, e.g., UGT344B4 in A. gossyppi confirms resistance to thimethoxam (Pan et al. 2018), sulfoxaflor (Ma et al. 2021), and imidacloprid (Chen et al. 2019), suggests that the involvement of UGTs is a general resistance mechanism, one which should be taken into consideration in designing new chemicals or repurposing them. On the other hand, a detailed study of UGTs in the Chinese honeybee (A. cerana cerana) revealed the beneficial effect of UGTs in the battle against pesticides that represent serious threat to these pollinators (Cui et al. 2020).