Cytotoxic drugs are highly efficacious and also have low therapeutic index. A great degree of caution needs to be exercised in their usage. To optimize the efficacy these drugs need to be given at maximum tolerated dose which leads to significant amount of toxicity to the patient. The fine balance between efficacy and safety is the key to the success of cytotoxic chemotherapeutics. However, it is possibly more rewarding to obtain that balance for this class drugs as the frequency of drug related toxicities are higher compared to the other therapeutic class and are potentially life threatening and may cause prolonged morbidity. Significant efforts have been invested in last three to four decades in therapeutic drug monitoring (TDM) research to understand the relationship between the drug concentration and the response achieved for therapeutic efficacy as well as drug toxicity for cytotoxic drugs. TDM evolved over this period and the evidence gathered favored its routine use for certain drugs. Since, TDM is an expensive endeavor both from economic and logistic point of view, to justify its use it is necessary to demonstrate that the implementation leads to perceivable improvement in the patient outcomes. It is indeed challenging to prove the utility of TDM in randomized controlled trials and at times may be nearly impossible to generate such data in view of the obvious findings and concern of compromising patient safety. Therefore, good quality data from well-designed observational study do add immense value to the scientific knowledge base, when they are examined in totality, despite the heterogeneity amongst them. This article compiles the summary of the evidence and the best practices for TDM for the three cytotoxic drug, busulfan, 5-FU and methotrexate. Traditional use of TDM or drug concentration data for dose modification has been witnessing a sea change and model informed precision dosing is the future of cytotoxic drug therapeutic management.

Background: Urothelial carcinoma is the most common malignancy of the bladder and is primarily considered as a disease of the elderly. Studies that address bladder tumor occurrence in young age groups are rare. Case Presentation: A 19-year-old male presented with a gross total painless hematuria. A histology after biopsy revealed a high-grade transitional cell carcinoma with lymph node metastasis. The patient succumbed to the disease on day 72 of the treatment. Here, we used whole-exome sequencing of a paired tumor-normal sample to identify the somatic mutations and the possible targets of treatment. Result: We predicted eight potential driver mutations (TP53 p.V157L, RB1 c.1498+1G>T, MED23 p.L1127P, CTNND1 p.S713C, NSD1 p.P2212A, MED17 p.G556V, DPYD p.Q814K, and SPEN p.S1078^*). In addition, we predicted deleterious mutations in genes involved in the ion channels (CACNA1S p.E1581K, CACNG1 p.P71T, CACNG8 p.G404W, GRIN2B p.A1096T, KCNC1 p.G16V, KCNH4 p.E874K, KCNK9 p.R131S, P2RX7 p.A296D, and SCN8A p.R558H). Conclusions: Most likely, mutations in genes involved in ion channels may be responsible for the aggressive behavior of a tumor. Ion channels are the second largest class of drug targets, and may thus serve as a putative potential therapeutic target in advanced stage urothelial carcinoma.

Background: Cost-effective management of Urinary Bladder Cancer (UBC) is an unmet need Aims: Our study aims to demonstrate the efficacy of a drug repurposing strategy by using disulfiram (DSF) and copper gluconate (Cu) as an add-on treatment combination to traditional GC-based chemother-apy against N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced UBC mice (C57J) model. Methods: Male C57BL/6J mice were given 0.05% BBN in drinking water ad libitum, and tumour for-mation was verified by histological and physical evaluation. Animals were subsequently divided into eight groups and received treatment with different drug combinations. Control animals received only ve-hicle (DMSO). At the end of the treatment schedule, the bladder tumour was excised and further used to check the expression (mRNA and protein) of ALDH1 isoenzymes using qRT-PCR, western blot, and IHC methods. Autophagy induction was assessed by quantifying the expression of LC3B and SQSTM1/p62 proteins through IHC. Biochemical analysis of superoxide dismutase (SOD), reduced glutathione (GSH), and lipid peroxidation levels in the freshly isolated tumours was performed to check the alterations in the antioxidant system caused by combination treatment. Results: We observed significant induction of an invasive form of bladder cancer in the mice after nine-teen weeks of BBN exposure. The animals began exhibiting early indications of inflammatory alterations as early as the sixth week following BBN treatment. Furthermore, the wet bladder weight and overall tu-mour burden were significantly decreased (p< 0.0001) by DSF-Cu co-treatment in addition to the GC-based chemotherapy. Real-time PCR analysis revealed that treatment with disulfiram and copper glu-conate significantly decreased (p<0.0001) the mRNA expression of ALDH1 isoenzymes. Comparing the triple drug combination group (GC+DSF-Cu) to the untreated mice, a significant rise in LC3B puncta (p<0.0001) and a decrease in P62/SQSTM1 (p=0.0002) were noted, indicating the induction of autophagy flux in the add-on group. When GC+DSF-Cu treated mice were compared to the untreated tumour group, a substantial decrease in ALDH1/2 protein expression was observed (p= 0.0029 in IHC and p<0.0001 in western blot). Lipid peroxidation was significantly higher (p<0.0001) in the triple drug combination group than in untreated mice. There was a simultaneous decrease in reduced glutathione (GSH) and en-zyme superoxide dismutase (SOD) levels (p<0.0001), which strongly suggests the generation of reactive oxygen species and induction of ferroptotic cell death in the add-on therapy group. Additionally, in both IHC and western blot assays, ALDH1A3 expression was found to be significantly increased (p=0.0033, <0.0001 respectively) in GC+DSF-Cu treated mice relative to the untreated group, suggesting a potential connection between the ferroptosis pathway and ALDH1A3 overexpression. Conclusion: It was found that disulfiram with copper treatment inhibits bladder tumour growth through ferroptosis-mediated ROS induction, which further activates the process of autophagy. Our results prove that DSF-Cu can be an effective add-on therapy along with the standard chemotherapy drugs for the treatment of UBC.