Toward a Better Understanding of the Complexity of Cancer Drug Resistance

Resistance to anticancer drugs is a complex process that results from alterations in drug targets; development of alternative pathways for growth activation; changes in cellular pharmacology, including increased drug efflux; regulatory changes that alter differentiation pathways or pathways for response to environmental adversity; and/or changes in the local physiology of the cancer, such as blood supply, tissue hydrodynamics, behavior of neighboring cells, and immune system response. All of these specific mechanisms are facilitated by the intrinsic hallmarks of cancer, such as tumor cell heterogeneity, redundancy of growth-promoting pathways, increased mutation rate and/or epigenetic alterations, and the dynamic variation of tumor behavior in time and space. Understanding the relative contribution of each of these factors is further complicated by the lack of adequate in vitro models that mimic clinical cancers. Several strategies to use current knowledge of drug resistance to improve treatment of cancer are suggested.

Interstrand Crosslink Repair as a Target for HDAC Inhibition

DNA interstrand crosslinks (ICLs) covalently connect complementary DNA strands. Consequently, DNA replication and transcription are hampered, DNA damage responses (DDR) are initiated, and cell death is triggered. Therefore, drugs inducing ICLs are effective against rapidly growing cancer cells. However, tumors engage a complicated enzymatic machinery to repair and survive ICLs. Several factors, including the post-translational acetylation/deacetylation of lysine residues within proteins, control this network. Histone deacetylases (HDACs) modulate the expression and functions of DNA repair proteins which remove ICLs and control the accessibility of chromatin. Accordingly, histone deacetylase inhibitors (HDACi) are small, pharmacologically and clinically relevant molecules that sensitize cancer cells to ICL inducers. We discuss the mechanism of ICL repair and targets of HDACi within this pathway.

Prospective evaluation of cisplatin- and carboplatin-mediated ototoxicity in paediatric and adult soft tissue and osteosarcoma patients

Platinum-compound chemotherapy is known to have ototoxic side-effects. However, there is a paucity of literature examining hearing function prospectively and longitudinally in cohorts containing paediatric and adult patients treated within the same cisplatin- or carboplatin-containing treatment trial protocols. In Germany, Austria and Switzerland, late effects of treatment for osteosarcoma and soft tissue sarcoma have been prospectively and longitudinally registered by the Late Effects Surveillance System since 1998. The aim of this study was to analyse cisplatin- and carboplatin-induced ototoxity in a group of 129 osteosarcoma and soft tissue sarcoma patients treated within the COSS-96, CWS-96 and CWS-2002P treatment trials. The cohort consisted of 112 children and 17 adults. The median age at diagnosis was 13.56 (IQR, 10.26-16.27) years. Follow-up was 6.97 (IQR, 0.87-15.63) months. Hearing function was examined by audiometry before and after platinum treatment. A total of 108 patients were treated with cisplatin with a median cumulative dose of 360 mg/m(2). Thirteen patients received carboplatin with a median cumulative dose of 1500 mg/m(2) and 8 patients were treated with both platinum compounds (median cisplatin dose, 240 mg/m(2); IQR, 240-360 mg/m(2) and median carboplatin dose: 1200 mg/m(2); IQR, 600-3000 mg/m(2)). Following cessation of therapy, 47.3% of the patients demonstrated a hearing impairment, namely 55 children (49.1%) and 6 adults (42.1%). Out of thirteen children treated with carboplatin with a cumulative dose of 1500 mg/m(2), six revealed a significant hearing impairment. Although ototoxicity caused by platinum compounds is considered irreversible, we identified hearing improvements over time in 11 children (9.8%) and 3 adults (17.6%). None of these patients received irradiation to the head. We conclude that hearing loss is frequent in children treated with protocols containing platinum compounds and recommend prospective testing via audiometry.

Long-term auditory complications after childhood cancer: A report from the Swiss Childhood Cancer Survivor Study

BACKGROUND

Auditory complications are an adverse event of childhood cancer treatment, especially common in children treated with platinum chemotherapy or cranial radiation. Variation between diagnostic childhood cancer groups has rarely been studied, and we do not know if the burden of auditory complications has changed over the last decades.

PROCEDURE

Within the Swiss Childhood Cancer Survivor Study, we sent a questionnaire to all survivors who were diagnosed at age 16 years or less between 1976 and 2005. We compared prevalence of self-reported hearing loss and tinnitus between all diagnostic childhood cancer groups and siblings, used multivariable logistic regression to analyze the effect of treatment-related factors on hearing loss, and compared the cumulative incidence of hearing loss between different periods of cancer diagnosis.

RESULTS

Prevalence of self-reported hearing loss was higher in survivors (10%) than in siblings (3%, P < 0.001), and highest in survivors of central nervous system tumors (25%). Significant risk factors were treatment with platinum compounds (carboplatin: odds ratio [OR] 2.4; cisplatin: OR 9.4), cranial radiation (>29 Gy: OR >1.7), or brain surgery (OR 2.2). Children diagnosed in 1986-1995, when platinum compounds came into widespread use, had a significantly higher cumulative incidence of hearing loss than those diagnosed in 1976-1985. In the most recent period, 1996-2005, the risk decreased again, both for patients treated with platinum compounds and with cranial radiation.

CONCLUSIONS

Our data show that the burden of hearing loss has stabilized in recently treated survivors, suggesting that survivors have benefited from new treatment regimens that use less ototoxic radiation and more carefully dosed platinum compounds.

PAXIP1 Potentiates the Combination of WEE1 Inhibitor AZD1775 and Platinum Agents in Lung Cancer

The DNA damage response (DDR) involves a complex network of signaling events mediated by modular protein domains such as the BRCA1 C-terminal (BRCT) domain. Thus, proteins that interact with BRCT domains and are a part of the DDR constitute potential targets for sensitization to DNA-damaging chemotherapy agents. We performed a pharmacologic screen to evaluate 17 kinases, identified in a BRCT-mediated interaction network as targets to enhance platinum-based chemotherapy in lung cancer. Inhibition of mitotic kinase WEE1 was found to have the most effective response in combination with platinum compounds in lung cancer cell lines. In the BRCT-mediated interaction network, WEE1 was found in complex with PAXIP1, a protein containing six BRCT domains involved in transcription and in the cellular response to DNA damage. We show that PAXIP1 BRCT domains regulate WEE1-mediated phosphorylation of CDK1. Furthermore, ectopic expression of PAXIP1 promotes enhanced caspase-3-mediated apoptosis in cells treated with WEE1 inhibitor AZD1775 (formerly, MK-1775) and cisplatin compared with cells treated with AZD1775 alone. Cell lines and patient-derived xenograft models expressing both PAXIP1 and WEE1 exhibited synergistic effects of AZD1775 and cisplatin. In summary, PAXIP1 is involved in sensitizing lung cancer cells to the WEE1 inhibitor AZD1775 in combination with platinum-based treatment. We propose that WEE1 and PAXIP1 levels may be used as mechanism-based biomarkers of response when WEE1 inhibitor AZD1775 is combined with DNA-damaging agents. Mol Cancer Ther; 15(7); 1669-81. ©2016 AACR.

Focal Adhesion Kinase in Ovarian Cancer: A Potential Therapeutic Target for Platinum and Taxane-Resistant Tumors

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase, which is an essential player in regulating cell migration, invasion, adhesion, proliferation, and survival. Its overexpression and activation have been identified in sixty-eight percent of epithelial ovarian cancer patients and this is significantly associated with higher tumor stage, metastasis, and shorter overall survival of these patients. Most recently, a new role has emerged for FAK in promoting resistance to taxane and platinum-based therapy in ovarian and other cancers. The development of resistance is a complex network of molecular processes that make the identification of a targetable biomarker in platinum and taxane-resistant ovarian cancer a major challenge. FAK overexpression upregulates ALDH and XIAP activity in platinum-resistant and increases CD44, YB1, and MDR-1 activity in taxaneresistant tumors. FAK is therefore now emerging as a prognostically significant candidate in this regard, with mounting evidence from recent successes in preclinical and clinical trials using small molecule FAK inhibitors. This review will summarize the significance and function of FAK in ovarian cancer, and its emerging role in chemotherapeutic resistance. We will discuss the current status of FAK inhibitors in ovarian cancers, their therapeutic competencies and limitations, and further propose that the combination of FAK inhibitors with platinum and taxane-based therapies could be an efficacious approach in chemotherapeutic resistant disease.

Interaction of the New Monofunctional Anticancer Agent Phenanthriplatin With Transporters for Organic Cations

Cancer treatment with platinum compounds is an important achievement of modern chemotherapy. However, despite the beneficial effects, the clinical impact of these agents is hampered by the development of drug resistance as well as dose-limiting side effects. The efficacy but also side effects of platinum complexes can be mediated by uptake through plasma membrane transporters. In the kidneys, plasma membrane transporters are involved in their secretion into the urine. Renal secretion is accomplished by uptake from the blood into the proximal tubules cells, followed by excretion into the urine. The uptake process is mediated mainly by organic cation transporters (OCT), which are expressed in the basolateral domain of the plasma membrane facing the blood. The excretion of platinum into the urine is mediated by exchange with protons via multidrug and toxin extrusion proteins (MATE) expressed in the apical domain of plasma membrane. Recently, the monofunctional, cationic platinum agent phenanthriplatin, which is able to escape common cellular resistance mechanisms, has been synthesized and investigated. In the present study, the interaction of phenanthriplatin with transporters for organic cations has been evaluated. Phenanthriplatin is a high affinity substrate for OCT2, but has a lower apparent affinity for MATEs. The presence of these transporters increased cytotoxicity of phenanthriplatin. Therefore, phenanthriplatin may be especially effective in the treatment of cancers that express OCTs, such as colon cancer cells. However, the interaction of phenanthriplatin with OCTs suggests that its use as chemotherapeutic agent may be complicated by OCT-mediated toxicity. Unlike cisplatin, phenanthriplatin interacts with high specificity with hMATE1 and hMATE2K in addition to hOCT2. This interaction may facilitate its efflux from the cells and thereby decrease overall efficacy and/or toxicity.

Gemcitabine and Platinum-Based Agents for the Prediction of Cancer-Associated Venous Thromboembolism: Results from the Vienna Cancer and Thrombosis Study

Simple Summary

Certain chemotherapy agents (gemcitabine, platinum-based agents) have been suggested to increase the risk of venous thromboembolism in cancer patients. Our aim was to evaluate, whether treatment with these agents can be used to better predict the risk of cancer-associated venous thromboembolism. Within a prospective observational cohort study, including 1409 patients, we found that treatment with gemcitabine and/or platinum-based agents is only of limited value in predicting the risk of venous thromboembolism beyond known risk factors included in an established risk prediction model (tumor type, blood levels of D-dimer). These findings suggest that a large part of the observed rate of venous thromboembolism in patients treated with these agents might be related to the underlying thrombotic risk rather than the agent itself.

Abstract

Gemcitabine and platinum-based agents could increase the risk of venous thromboembolism (VTE) in patients with cancer. We evaluated the additive predictive utility of these agents towards cancer-associated VTE beyond a recently developed and externally validated clinical prediction model, which was based on tumor entity and continuous D-dimer levels. Analysis was performed in the derivation cohort of this model, obtained from the Vienna Cancer and Thrombosis Study (CATS), a prospective observational cohort study (n = 1409). Patients were followed for the occurrence of VTE for a maximum of two years. Competing-risk analysis was performed to obtain cumulative incidences and to conduct between-group comparisons of VTE risk. Cumulative two-year incidences of VTE were not elevated with gemcitabine treatment (10.2% vs. 7.5%, p = 0.148), whereas they were higher for platinum-based therapy (11.6% vs. 5.9%, p < 0.001). In a multivariable analysis, adjusting for tumor site category and D-dimer, gemcitabine was not associated with increased risk of VTE (subdistribution hazard ratio (SHR) 0.82, 95% confidence interval (CI) 0.53–1.28, p = 0.390), whereas platinum-based therapy predicted for a numerically increased VTE risk (SHR 1.44, 95% CI 0.96–2.17, p = 0.080). Similar results were obtained in a sensitivity analysis (updated cohort, n = 1870). Our findings suggest limited additional value of chemotherapy for the prediction of cancer-associated VTE, beyond a validated clinical prediction model.

Combination chemotherapy with 5-fluorouracil and heptaplatin as first-line treatment in patients with advanced gastric cancer

Heptaplatin is a recently developed platinum derivative. This agent has been reported to have a response rate of 17% as a single agent, and tolerable toxicity in the treatment of advanced gastric cancer. The aim of this study was to evaluate the efficacy and toxicity of a combination of 5-fluorouracil (5-FU) and heptaplatin in patients with advanced gastric cancer. Forty-seven chemotherapy-naive patients with advanced or recurred gastric cancer were recruited. 5-FU was administered over 120 hr by continuous intravenous infusion from day 1 to 5, at a daily dose of 1,000 mg/m2 and heptaplatin was administered over 1 hr by intravenous infusion on day 1 at 400 mg/m2, and this cycle was repeated every 4 weeks. The response rate was 21%, median progression-free survival was 1.9 months (95% CI, 1.6 to 2.2 months). Median overall survival was 6.2 months (95% CI, 4 to 8.4 months) and the 1-yr survival rate was 29% for all patients. The most frequent toxicity was proteinuria. Toxicities were generally mild and reversible. This study demonstrates that the combination of 5-FU/heptaplatin combination is less active but tolerated in patients with advance gastric cancer.

Highlights of New Strategies to Increase the Efficacy of Transition Metal Complexes for Cancer Treatments

Although important progress has been made, cancer still remains a complex disease to treat. Serious side effects, the insurgence of resistance and poor selectivity are some of the problems associated with the classical metal-based anti-cancer therapies currently in clinical use. New treatment approaches are still needed to increase cancer patient survival without cancer recurrence. Herein, we reviewed two promising-at least in our opinion-new strategies to increase the efficacy of transition metal-based complexes. First, we considered the possibility of assembling two biologically active fragments containing different metal centres into the same molecule, thus obtaining a heterobimetallic complex. A critical comparison with the monometallic counterparts was done. The reviewed literature has been divided into two groups: the case of platinum; the case of gold. Secondly, the conjugation of metal-based complexes to a targeting moiety was discussed. Particularly, we highlighted some interesting examples of compounds targeting cancer cell organelles according to a third-order targeting approach, and complexes targeting the whole cancer cell, according to a second-order targeting strategy.

Nanocarriers containing platinum compounds for combination chemotherapy

Platinum compounds-based drugs are used widely in the clinic for the treatment of many types of cancer. However, serious undesirable side effects and intrinsic or acquired resistance limit their successful clinic use. Nanocarrier-based combination chemotherapy is considered to be an effective strategy to resolve these challenges. This review introduces the recent advance in nanocarriers containing platinum compounds for combination cancer chemotherapy, including liposomes, polymer nanoparticles, polymer micelles, mesoporous silica nanoparticles, carbon nanohors, polymer-caged nanobins, carbon nanotube, nanostructured lipid carriers, solid lipid nanoparticles, and multilayered fiber mats in detail.

Neurotoxic Effects of Platinum Compounds: Studies in vivo on Intracellular Calcium Homeostasis in the Immature Central Nervous System

Platinum compounds cause significant clinical neurotoxicity. Several studies highlight neurological complications especially in paediatric oncology patients with Central Nervous System (CNS) and non-CNS malignancies. To understand the toxicity mechanisms of platinum drugs at cellular and molecular levels in the immature brain, which appears more vulnerable to injury than in the adult one, we compared the effects in vivo of the most used platinum compounds, i.e., cisdichlorodiammineplatinum (cisplatin, cisPt), and the new [Pt(O,O′-acac)(γ-acac)(DMS)] (PtAcacDMS). As models of developing brain areas, we have chosen the cerebellum and hippocampus dentate gyrus. Both areas show the neurogenesis events, from proliferation to differentiation and synaptogenesis, and therefore allow comparing the action of platinum compounds with DNA and non-DNA targets. Here, we focused on the changes in the intracellular calcium homeostasis within CNS architecture, using two immunohistochemical markers, the calcium buffer protein Calbindin and Plasma Membrane Calcium ATPase. From the comparison of the cisPt and PtAcacDMS effects, it emerges how essential the equilibrium and synergy between CB and PMCA1 is or how important the presence of at least one of them is to warrant the morphology and function of nervous tissue and limit neuroarchitecture damages, depending on the peculiar and intrinsic properties of the developing CNS areas.

High plasma exposure to pemetrexed leads to severe hyponatremia in patients with advanced non small cell lung cancer receiving pemetrexed-platinum doublet chemotherapy

BACKGROUND

Pemetrexed-platinum doublet therapy is a standard treatment for stage IIIb/IV nonsquamous non small cell lung cancer (NSCLC). While the regimen is associated with several grade ≥3 toxicities, hyponatremia is not a commonly reported adverse effect. Here we report an unusually high incidence of grade ≥3 hyponatremia in Indian patients receiving pemetrexed-platinum doublet, and the pharmacological basis for this phenomenon.

METHODS

Forty-six patients with advanced NSCLC were enrolled for a bioequivalence study of two pemetrexed formulations. All patients received the pemetrexed-platinum doublet for six cycles followed by single-agent pemetrexed maintenance until progression. Pharmacokinetic blood samples were collected at predefined time points during the first cycle and the concentration-time profile of pemetrexed was investigated by noncompartmental analysis. Hyponatremic episodes were investigated with serum electrolytes, serum osmolality, urinary sodium, and urine osmolality.

RESULTS

Sixteen of 46 patients (35%) had at least one episode of grade ≥3 hyponatremia. Twenty-four episodes of grade ≥3 hyponatremia were observed in 200 cycles of doublet chemotherapy. Plasma exposure to pemetrexed was significantly higher in patients with high-grade hyponatremia than in those with low-grade or no hyponatremia (P=0.063 and P=0.001, respectively). Pemetrexed clearance in high-grade hyponatremia was quite low compared with normal and low-grade hyponatremia (P=0.001 and P=0.055, respectively). Median pemetrexed exposure in this cohort was much higher than that reported in the literature from Western studies.

CONCLUSION

Higher exposure to pemetrexed is associated with grade ≥3 hyponatremia. The pharmacogenetic basis for higher exposure to pemetrexed in Indian patients needs further investigation.

Ruthenium(II) and Platinum(II) Complexes with Biologically Active Aminoflavone Ligands Exhibit In Vitro Anticancer Activity

Continuing our studies on the mechanisms underlying the cytotoxicity of potential drugs, we have described several aspects of the in vitro anticancer activity of ruthenium(II) and platinum(II) complexes with bioactive, synthetic aminoflavone ligands. We examined the mechanism of proapoptotic activity of cis-dichlorobis(3-imino-2-methoxyflavanone)ruthenium(II), cis-dichlorobis(3-imino-2-ethoxyflavanone)ruthenium(II), and trans-dichlorobis(3-aminoflavone)platinum(II). Cisplatin was used as a reference compound. The cytotoxicity was investigated by MTT assay. The mechanism of proapoptotic activity of the tested compounds was investigated by evaluation of caspase-8 activity, cytometric analysis of annexin-V positive cells, and mitochondrial potential loss measurement. The results showed that ruthenium compounds break partially or completely the cisplatin resistance by activating the caspase 8-dependent apoptosis pathway and loss of mitochondrial membrane potential. Platinum compounds also have a cytostatic effect, but their action requires more exposure time. Potential mechanisms underlying drug resistance in the two pairs of cancer cell lines were investigated: total glutathione content, P-glycoprotein activity, and differences in the activity of DNA repair induced by nucleotide excision. Results showed that cisplatin-resistant cells have elevated glutathione levels relative to sensitive cells. Moreover, they indicated the mechanisms enabling cells to avoid apoptosis caused by DNA damage. Pg-P activity has no effect on the development of cisplatin resistance in the cell lines described.

Flow cytometric analyses of the characteristics of tumor cells treated with two platinum compounds: 1,1-cyclobutanedicarboxylato(2-aminomethylpyrrolidine)- platinum(II) and cisplatin

In order to reduce the toxicities of cisplatin (DDP) and/or to improve antitumor efficacy, a large number of new platinum analogues have been synthesized. 1,1-Cyclobutanedicarboxylato(2-aminomethylpyrrolidine)platin um(II) (DWA2114R) is one of them. In this study, we characterized the action mechanism of DWA2114R flow-cytometrically in 3 human lung cancer cell lines by using bromodeoxyuridine (BrdUrd), rhodamine 123 (Rho) and Ki-67 antibody (Ab), and compared the results with those for DDP. We found that the actions of these 2 platinum analogues were characteristically different at the subcellular level. Our observations may be summarized as follows. a) Simultaneous exposure of cells to DDP and BrdUrd resulted in decreases in fluorescence intensity, i.e. in the amount of BrdUrd incorporated into single-stranded DNA. b) DDP appears to be approximately 20-fold more active than DWA2114R in producing cell cycle perturbation. c) In PC-6 small cell carcinoma cells, DDP induced decreases in S phase cells and accumulation of cells in the G2M phase, whereas in PC-10 squamous carcinoma and PC-3 adenocarcinoma cells DDP produced S phase cell accumulation. Weak but similar changes occurred with DWA2114R. d) The high Ki-67 antigen cell population was decreased by treatment with either DDP or DWA2114R, but DDP reduced the low Ki-67 antigen population more than DWA2114R. e) In PC-10 and PC-6 cells, DDP suppressed Rho incorporation into live mitochondria, whereas DWA2114R produced no change in Rho incorporation. PC-3 cells were not affected by either DDP or DWA2114R. It is likely that these differences reflect the biological activities of DDP and DWA2114R.

Incorporation of N7-Platinated Guanines into Thermus Aquaticus (Taq) DNA Polymerase: Atomistic Insights from Molecular Dynamics Simulations

In this work, we elucidated some key aspects of the mechanism of action of the cisplatin anticancer drug, cis-[Pt(NH₃)₂Cl₂], involving direct interactions with free nucleotides. A comprehensive in silico molecular modeling analysis was conducted to compare the interactions of Thermus aquaticus (Taq) DNA polymerase with three distinct N7-platinated deoxyguanosine triphosphates: [Pt(dien)(N7-dGTP)] (1), cis-[Pt(NH₃)₂Cl(N7-dGTP)] (2), and cis-[Pt(NH₃)₂(H₂O)(N7-dGTP)] (3) {dien = diethylenetriamine; dGTP = 5'-(2'-deoxy)-guanosine-triphosphate}, using canonical dGTP as a reference, in the presence of DNA. The goal was to elucidate the binding site interactions between Taq DNA polymerase and the tested nucleotide derivatives, providing valuable atomistic insights. Unbiased molecular dynamics simulations (200 ns for each complex) with explicit water molecules were performed on the four ternary complexes, yielding significant findings that contribute to a better understanding of experimental results. The molecular modeling highlighted the crucial role of a specific α-helix (O-helix) within the fingers subdomain, which facilitates the proper geometry for functional contacts between the incoming nucleotide and the DNA template needed for incorporation into the polymerase. The analysis revealed that complex 1 exhibits a much lower affinity for Taq DNA polymerase than complexes 2-3. The affinities of cisplatin metabolites 2-3 for Taq DNA polymerase were found to be quite similar to those of natural dGTP, resulting in a lower incorporation rate for complex 1 compared to complexes 2-3. These findings could have significant implications for the cisplatin mechanism of action, as the high intracellular availability of free nucleobases might promote the competitive incorporation of platinated nucleotides over direct cisplatin attachment to DNA. The study's insights into the incorporation of platinated nucleotides into the Taq DNA polymerase active site suggest that the role of platinated nucleotides in the cisplatin mechanism of action may have been previously underestimated.

The Efficacy and Safety of First-line Chemotherapies for Advanced Biliary Tract Cancer: A Network Meta-analysis

Major chemotherapeutic drugs for advanced biliary tract cancer (ABTC) include gemcitabine, fluoropyrimidines and platinum compounds, but the optimum combination of them remains inconclusive. The main objective of this network meta-analysis was to compare the efficacy and safety of first-line chemotherapies for ABTC.

Methods: We searched PubMed, EMBASE, the Cochrane library and Science Direct for relevant controlled trials until May 2017. We estimated the Hazard ratios (HRs) for survival time and odds ratios (ORs) for response rate and toxic effects among different therapies. All data were calculated by Aggregate Data Drug Information System (ADDIS) v2.0 online and STATA software.

Results: 16 trials involving 2245 patients and 10 regimens were included in this study. In terms of the objective response rate, Cap plus CIS (CapC) exhibited better performance than FU (OR 5.46, 95% CI 1.07-56.63). Gem plus S-1 (GS) was superior to Gem (OR 4.72, 95% CI 1.31-17.02) and FU (OR 9.08, 95% CI 1.56-89.20). Also, GS had an overall survival benefit compared to FU and Gem, with a HR of 0.51 (95% CI 0.28-0.96) and 0.43 (95% CI 0.20-0.93), respectively. Compared with FU, Gem plus OXA (Gemox) prolonged the OS (HR 0.57, 95% CI 0.32-0.96). And FU was also inferior to FP (HR 1.88, 95% CI 1.07-3.16). The PFS did not differ between all regiments. The incidence of grade 3 or 4 hematological toxic effects appeared to be higher in the Gem-based chemotherapies. In regard to nonhematological adverse events, grade 3 or 4 diarrhea and stomotitis occurred more frequently in S-1-based groups. In addition, the Cap plus CIS combination (CapC) were more likely to cause vomiting, stomotitis and hand-foot syndrome. As for peripheral neuropathy, Gem plus OXA (Gemox), CapC and GC were associated with higher risk. There was no difference among different treatments with respect to anorexia, fatigue, nausea, pigmentation, renal dysfunction and asthenia.

Conclusion: Physicians should discuss with the patients the different options outlining potential benefit and toxicity since no clear evidence of an approach of choice can be produced.

Platinum-Nucleos(t)ide Compounds as Possible Antimetabolites for Antitumor/Antiviral Therapy: Properties and Perspectives

Nucleoside analogues (NAs) are a family of compounds which include a variety of purine and pyrimidine derivatives, widely used as anticancer and antiviral agents. For their ability to compete with physiological nucleosides, NAs act as antimetabolites exerting their activity by interfering with the synthesis of nucleic acids. Much progress in the comprehension of their molecular mechanisms has been made, including providing new strategies for potentiating anticancer/antiviral activity. Among these strategies, new platinum-NAs showing a good potential to improve the therapeutic indices of NAs have been synthesized and studied. This short review aims to describe the properties and future perspectives of platinum-NAs, proposing these complexes as a new class of antimetabolites.

Oxaliplatin-induced papilledema: Rare case report

Papilledema is the presence of bilateral optic disc edema in the presence of raised intracranial pressure and often is symmetric. We report a case of a 70-year-old male with rectal carcinoma on chemotherapy presented with minimal drop in visual acuity. The patient has bilateral disc edema and investigations including computed tomography and cerebrospinal fluid opening pressure were normal and no evidence of brain metastasis has been found. The patient was on oxaliplatin regimen and literature search has shown very few cases of platinum chemotherapy agents-induced papilledema. So far to our knowledge, oxaliplatin-induced papilledema has not been reported and knowing this condition can be sight saving for ill patients.

Checkpoint Kinase 1 Pharmacological Inhibition Synergizes with DNA-Damaging Agents and Overcomes Platinum Resistance in Basal-Like Breast Cancer

Basal-like breast cancer is an incurable disease with limited therapeutic options, mainly due to the frequent development of anti-cancer drug resistance. Therefore, identification of druggable targets to improve current therapies and overcome these resistances is a major goal. Targeting DNA repair mechanisms has reached the clinical setting and several strategies, like the inhibition of the CHK1 kinase, are currently in clinical development. Here, using a panel of basal-like cancer cell lines, we explored the synergistic interactions of CHK1 inhibitors (rabusertib and SAR020106) with approved therapies in breast cancer and evaluated their potential to overcome resistance. We identified a synergistic action of these inhibitors with agents that produce DNA damage, like platinum compounds, gemcitabine, and the PARP inhibitor olaparib. Our results demonstrated that the combination of rabusertib with these chemotherapies also has a synergistic impact on tumor initiation, invasion capabilities, and apoptosis in vitro. We also revealed a biochemical effect on DNA damage and caspase-dependent apoptosis pathways through the phosphorylation of H2AX, the degradation of full-length PARP, and the increase of caspases 3 and 8 activity. This agent also demonstrated synergistic activity in a platinum-resistant cell line, inducing an increase in cell death in response to cisplatin only when combined with rabusertib, while no toxic effect was found on non-tumorigenic breast tissue-derived cell lines. Lastly, the combination of CHK1 inhibitor with cisplatin and gemcitabine resulted in more activity than single or double combinations, leading to a higher apoptotic effect. In conclusion, in our study we identify therapeutic options for the clinical development of CHK1 inhibitors, and confirm that the inhibition of this kinase can overcome acquired resistance to cisplatin.

Diversity of dose-individualization and therapeutic drug monitoring practices of platinum compounds: a review

Introduction: Platinum-derived drugs are commonly used for the treatment of solid tumors. The differences in chemical structures of these molecules lead to different pharmacological properties, in terms of indication, efficacy, and toxicity. Their pharmacokinetics (PK) differ according to their respective renal elimination and have led to many studies investigating their dose optimization. Area covered: This review attempts to summarize and compare PK and pharmacodynamics of cisplatin, carboplatin, and oxaliplatin, with an emphasis on differences of dose calculations and opportunities for therapeutic drug monitoring (TDM) in various patient populations. Expert opinion: Although cisplatin and carboplatin can be considered as analogs since they share the same DNA interacting properties, the slower hydrolysis of the latter results in a better safety profile. Carboplatin is the only drug in oncology to be administrated according to a target area under the curve of concentration versus time, considering that its PK variability is almost fully explained by renal function, not by body size. This enables individual dosing based on predicted carboplatin clearance (along with patients renal characteristics) or on actual clearance with TDM, especially in a high-dose protocol.

Severity of hearing loss after platinum chemotherapy in childhood cancer survivors

BACKGROUND

Hearing loss is a potential side effect from childhood cancer treatment. We described the severity of hearing loss assessed by audiometry in a representative national cohort of childhood cancer survivors (CCS) and identified clinical risk factors.

PROCEDURE

We included all CCS from the Swiss Childhood Cancer Registry who were diagnosed ≤18 age and treated with platinum-based chemotherapy between 1990 and 2014. We extracted audiograms, treatment-related information, and demographic data from medical records. Two reviewers independently assessed the severity of hearing loss at latest follow-up using the Münster Ototoxicity Scale. We used ordered logistic regression to identify clinical risk factors for severity of hearing loss.

RESULTS

We analyzed data from 270 CCS. Median time from cancer diagnosis to last audiogram was 5 years (interquartile range 2.5-8.1 years). We found 53 (20%) CCS with mild, 78 (29%) with moderate, and 75 (28%) with severe hearing loss. Higher severity grades were associated with (a) younger age at cancer diagnosis (odds ratio [OR] 5.4, 95% confidence interval [CI]: 2.5-12.0 for <5 years); (b) treatment in earlier years (OR 4.8, 95% CI: 2.1-11.0 for 1990-1995); (c) higher cumulative cisplatin doses (OR 13.5, 95% CI: 4.7-38.8 for >450 mg/m² ); (d) concomitant cranial radiation therapy (CRT) (OR 4.4, 95% CI: 2.5-7.8); and (e) hematopoietic stem cell transplantation (HSCT) (OR 2.7, 95% CI: 1.0-7.2).

CONCLUSION

Three of four CCS treated with platinum-based chemotherapy experienced some degree of hearing loss. We recommend closely monitoring patient's hearing function if treated at a young age with high cumulative cisplatin doses, and concomitant CRT as part of long-term care.

High Antimetastatic Activity of Platin Liposomal Form after Lyophilization and Storage

Antimetastatic activity of Platin in lyophilized liposomes stored for 7 years after fabrication was evaluated. The main flaw of liposomes as vehicles for drug delivery to the tumors is their high affinity for the liver, which accumulates a great amount thereof. This property of liposomes can be used for adjuvant therapy of operable primary tumors metastasizing to the liver. It is shown on the model of mouse GA-1 tumor metastases in the liver that platinum(II) complex compound Platin in phosphatidylcholine-cholesterol liposomes, stored for 7 years after lyophilization, causes complete cure of 40% animals, while free Platin prolongs the lifespan of mice with tumors by only 31.7% vs. control (no treatment).

Synergistic strategies: histone deacetylase inhibitors and platinum-based drugs in cancer therapy

INTRODUCTION

The synergistic combination of histone deacetylase inhibitors and platinum-based medicines represents a promising therapeutic strategy to efficacy and overcome drug resistance in cancer therapy, necessitating a comprehensive understanding on their molecular interactions and clinical potential.

AREAS COVERED

The objective of presented review is to investigate the molecular pathways of platinum medicines and HDAC inhibitors. A comprehensive literature review from 2011 to 2024 was conducted across multiple databases like MEDLINE, PubMed, Google Scholar, Science Direct, Scopus and official websites of ClinicalTrial.gov to explore publications on HDAC inhibitors, platinum drugs, and combination cancer therapies, revealing preliminary evidence of innovative treatment strategies involving HDAC inhibitors and platinum chemotherapeutics. Several new platinum (IV) complexes, with HDAC inhibitory moieties and better cytotoxicity profiles than conventional platinum drugs, are also reviewed here.

EXPERT OPINION

The above combination has great potential in cancer treatment, however managing toxicity, dosage regimens, and patient selection biomarkers are problematic. More selective HDAC inhibitors and innovative delivery techniques are potential areas for future research. An adaptation toward changing cancer therapeutic landscapes, highlights combining HDAC inhibitors with platinum-based medicines serves as a new concept for personalized medicine, however, a deeper research is still needed at this time.