RESUMEN
DNA adducting drugs, including alkylating agents and platinum-containing drugs, are prominent in cancer chemotherapy. Their mechanisms of action involve direct interaction with DNA, resulting in the formation of DNA addition products known as DNA adducts. While these adducts are well-accepted to induce cancer cell death, understanding of their specific chemotypes and their role in drug therapy response remain limited. This perspective aims to address this gap by investigating the metabolic activation and chemical characterization of DNA adducts formed by the U.S. FDA-approved drugs. Moreover, clinical studies on DNA adducts as potential biomarkers for predicting patient responses to drug efficacy are examined. The overarching goal is to engage the interest of medicinal chemists and stimulate further research into the use of DNA adducts as biomarkers for guiding personalized cancer treatment.
Asunto(s)
Aductos de ADN , Neoplasias , Humanos , Aductos de ADN/uso terapéutico , ADN/química , Neoplasias/tratamiento farmacológico , Platino (Metal) , BiomarcadoresRESUMEN
Peiminine, the primary biologically active compound from Fritillaria thunbergii Miq., has demonstrated significant pharmacological activities. Doxorubicin is one of the most potent chemotherapeutic agents for breast cancer (BC). This study was designed to investigate the efficacy and underlying mechanisms of Peiminine combined with Doxorubicin in treating BC. Our results demonstrated that the combination of Peiminine and 1â¯mg/kg Doxorubicin exhibited more significant suppression of tumor growth compared with the monotherapy in MDA-MB-231 xenograft nude mice model, which is comparable to the effect of 3â¯mg/kg Doxorubicin in vivo. Notably, the 3â¯mg/kg Doxorubicin monotherapy resulted in organ toxicity, specifically in the liver and heart, whereas no toxicity was observed in the combination group. In vitro, this combined treatment exhibited a synergistic reduction on the viability of BC cells. Peiminine enhanced the cell cycle arrest and DNA damage induced by Doxorubicin. Furthermore, the combination treatment effectively blocked DNA repair by inhibiting the MAPKs signaling pathways. And ZEB1 knockdown attenuated the combined effect of Peiminine and Doxorubicin on cell viability and DNA damage. In conclusion, our study found that the combination of Peiminine and Doxorubicin showed synergistic inhibitory effects on BC both in vivo and in vitro through enhancing Doxorubicin-induced DNA damage. These findings support that their combination is a novel and promising therapeutic strategy for treating BC.
Asunto(s)
Neoplasias de la Mama , Cevanas , Ratones , Animales , Humanos , Femenino , Neoplasias de la Mama/tratamiento farmacológico , Ratones Desnudos , Doxorrubicina/farmacología , Doxorrubicina/uso terapéutico , Aductos de ADN/farmacología , Aductos de ADN/uso terapéutico , Línea Celular Tumoral , Apoptosis , Homeobox 1 de Unión a la E-Box con Dedos de ZincRESUMEN
BACKGROUND: Oxaliplatin (Oxa) is the first-line chemotherapy drug for colorectal cancer (CRC), and Oxa resistance is crucial for treatment failure. Prostaglandin F2α synthase (PGF2α) (PGFS), an enzyme that catalyzes the production of PGF2α, is involved in the proliferation and growth of a variety of tumors. However, the role of PGFS in Oxa resistance in CRC remains unclear. AIM: To explore the role and related mechanisms of PGFS in mediating Oxa resistance in CRC. METHODS: The PGFS expression level was examined in 37 pairs of CRC tissues and paracancerous tissues at both the mRNA and protein levels. Overexpression or knockdown of PGFS was performed in CRC cell lines with acquired Oxa resistance (HCT116-OxR and HCT8-OxR) and their parental cell lines (HCT116 and HCT8) to assess its influence on cell proliferation, chemoresistance, apoptosis, and DNA damage. For determination of the underlying mechanisms, CRC cells were examined for platinum-DNA adducts and reactive oxygen species (ROS) levels in the presence of a PGFS inhibitor or its products. RESULTS: Both the protein and mRNA levels of PGFS were increased in the 37 examined CRC tissues compared to the adjacent normal tissues. Oxa induced PGFS expression in the parental HCT116 and HCT8 cells in a dose-dependent manner. Furthermore, overexpression of PGFS in parental CRC cells significantly attenuated Oxa-induced proliferative suppression, apoptosis, and DNA damage. In contrast, knockdown of PGFS in Oxa-resistant HCT116 and HCT8 cells (HCT116-OxR and HCT8-OxR) accentuated the effect of Oxa treatment in vitro and in vivo. The addition of the PGFS inhibitor indomethacin enhanced the cytotoxicity caused by Oxa. Treatment with the PGFS-catalyzed product PGF2α reversed the effect of PGFS knockdown on Oxa sensitivity. Interestingly, PGFS inhibited the formation of platinum-DNA adducts in a PGF2α-independent manner. PGF2α exerts its protective effect against DNA damage by reducing ROS levels. CONCLUSION: PGFS promotes resistance to Oxa in CRC via both PGF2α-dependent and PGF2α-independent mechanisms.
Asunto(s)
Neoplasias Colorrectales , Platino (Metal) , Humanos , Oxaliplatino/farmacología , Oxaliplatino/uso terapéutico , Platino (Metal)/farmacología , Platino (Metal)/uso terapéutico , Aductos de ADN/farmacología , Aductos de ADN/uso terapéutico , Especies Reactivas de Oxígeno , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , ARN Mensajero/metabolismo , Prostaglandinas , Resistencia a Antineoplásicos/genética , Línea Celular TumoralRESUMEN
Cisplatin, a widely prescribed chemotherapeutic agent for treating solid tumors, induces DNA adducts and activates cellular defense mechanisms, including DNA repair, cell cycle checkpoint control, and apoptosis. Considering the circadian rhythmicity displayed by most chemotherapeutic agents and their varying therapeutic efficacy based on treatment timing, our study aimed to investigate whether the circadian clock system influences the DNA damage responses triggered by cisplatin in synchronized cells. We examined the DNA damage responses in circadian-synchronized wild-type mouse embryonic fibroblasts (WT-MEF; clock-proficient cells), cryptochrome1 and 2 double knock-out MEF (CRYDKO; clock-deficient cells), and mouse hepatocarcinoma Hepa1c1c7 cells. Varying the treatment time resulted in a significant difference in the rate of platinum-DNA adduct removal specifically in circadian-synchronized WT-MEF, while CRYDKO did not exhibit such variation. Moreover, diurnal variation in other DNA damage responses, such as cell cycle checkpoint activity indicated by p53 phosphorylation status and apoptosis measured by DNA break frequency, was observed only in circadian-synchronized WT-MEF, not in CRYDKO or mouse hepatocarcinoma Hepa1c1c7 cells. These findings highlight that the DNA damage responses triggered by cisplatin are indeed governed by circadian control exclusively in clock-proficient cells. This outcome bears potential implications for enhancing or devising chronotherapy approaches for cancer patients.
Asunto(s)
Relojes Circadianos , Neoplasias , Animales , Ratones , Cisplatino/farmacología , Cisplatino/uso terapéutico , Aductos de ADN/uso terapéutico , Daño del ADN , Fibroblastos/metabolismo , Reparación del ADN , Relojes Circadianos/genética , Neoplasias/genética , ApoptosisRESUMEN
Protein neddylation is catalyzed by a neddylation activating enzyme (NAE, E1), an E2 conjugating enzyme, and an E3 ligase. In various types of human cancers, the neddylation pathway is abnormally activated. Our previous study validated that the neddylation E2 UBE2F is a promising therapeutic target in lung cancer. Although the NAE inhibitor MLN4924/pevonedistat is currently under clinical investigation as an anti-cancer agent, there are no small molecules available that selectively target UBE2F. Here, we report, for the first time, the discovery, via structure-based virtual screen and chemical optimization, of such a small molecule, designated as HA-9104. HA-9104 binds to UBE2F, reduces its protein levels, and consequently inhibits cullin-5 neddylation. Blockage of cullin-5 neddylation inactivates cullin-RING ligase-5 (CRL5) activity, leading to accumulation of the CRL5 substrate, NOXA, to induce apoptosis. Moreover, HA-9104 appears to form the DNA adduct via its 7-azaindole group to induce DNA damage and G2/M arrest. Biologically, HA-9104 effectively suppresses the growth and survival of lung cancer cells and confers radiosensitization in both in vitro cell culture and in vivo xenograft tumor models. In summary, we discovered a small molecule, designated HA-9104, that targets the UBE2F-CRL5 axis with anti-cancer activity alone or in combination with radiation.
Asunto(s)
Apoptosis , Neoplasias Pulmonares , Apoptosis/genética , Línea Celular Tumoral , Proteínas Cullin/genética , Proteínas Cullin/metabolismo , Ciclopentanos , Aductos de ADN/uso terapéutico , Puntos de Control de la Fase G2 del Ciclo Celular , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/radioterapia , Pirimidinas , Enzimas Ubiquitina-Conjugadoras/genética , Enzimas Ubiquitina-Conjugadoras/metabolismo , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Despite many nano-based strategies devoted to delivering cisplatin for tumor therapy, its clinical benefits are compromised by poor tissue penetration and limited DNA adducts formation of the drug. Herein, a cisplatin loading nanomotor based janus structured Ag-polymer is developed for cisplatin delivery of deeper tissue and increased DNA adducts formation. The nanomotor displayed a self-propelled tumor penetration fueled by hydrogen peroxide (H2O2) in tumor tissues, which is catalytically decomposed into a large amount of oxygen bubbles by Ag nanoparticles (NPs). Notably, cisplatin could elevate the intracellular H2O2 level through cascade reactions, further promote the degradation of Ag NPs accompanied with the Ag+ release, which could downregulate intracellular Cl- through the formation of AgCl precipitate, thereby enhancing cisplatin dechlorination and Pt-DNA formation. Moreover, polymer can also inhibit the activity of ALKBH2 (a Fe2+-dependent DNA repair enzyme) by chelating intracellular Fe2+ to increase the proportion of irreparable Pt-DNA cross-links. It is found that deep tissue penetration, as well as the increased formation and maintenance of Pt-DNA adducts induced by the nanomotor afford 80% of tumor growth inhibition with negligible toxicity. This work provides an important perspective of resolving chemotherapeutic barriers for boosting cisplatin therapy.
Asunto(s)
Antineoplásicos , Nanopartículas del Metal , Neoplasias , Antineoplásicos/uso terapéutico , Cisplatino/farmacología , Cisplatino/uso terapéutico , ADN/metabolismo , Aductos de ADN/uso terapéutico , Humanos , Peróxido de Hidrógeno , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Oxígeno , Polímeros/uso terapéutico , Plata/uso terapéuticoRESUMEN
This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors and sanctioned by the Editor-in-Chief. The authors found errors in the data presentation - apoptotic statistics and in vivo distribution - which makes the conclusion not representative. The authors express sincere apologies for the error and inconvenience to readers.
Asunto(s)
Antineoplásicos/administración & dosificación , Aductos de ADN/administración & dosificación , Doxorrubicina/administración & dosificación , Portadores de Fármacos/administración & dosificación , Oro/administración & dosificación , Nanotubos , Neoplasias de la Próstata/terapia , Receptores de LDL/metabolismo , Animales , Antineoplásicos/química , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Terapia Combinada , Aductos de ADN/química , Aductos de ADN/uso terapéutico , Doxorrubicina/química , Doxorrubicina/uso terapéutico , Portadores de Fármacos/química , Portadores de Fármacos/uso terapéutico , Oro/química , Oro/uso terapéutico , Humanos , Hipertermia Inducida , Masculino , Ratones Endogámicos BALB C , Ratones Desnudos , Nanotubos/química , Péptidos/química , Polietilenglicoles/química , Neoplasias de la Próstata/patología , Carga Tumoral/efectos de los fármacosRESUMEN
In cancer therapy, it is imperative to increase the efficacy and reduce side effects of chemotherapeutic drugs. Nanotechnology offers the unique opportunity to overcome these barriers. In particular, in the last few years, DNA nanostructures have gained attention for their biocompatibility, easy customized synthesis and ability to deliver drugs to cancer cells. Here, an open-caged pyramidal DNA@Doxorubicin (Py-Doxo) nanostructure was constructed with 10 DNA sequences of 26-28 nucleotides for drug delivery to cancer cells. The synthesized DNA nanostructures are sufficiently stable in biological medium. Py-Doxo exhibited significantly enhanced cytotoxicity of the delivered doxorubicin to breast and liver cancer cells up to twofold compared to free doxorubicin. This study demonstrates the importance of the shape and structure of the designed transporter DNA nanostructures for biomedical applications.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Aductos de ADN/uso terapéutico , Doxorrubicina/uso terapéutico , Nanoestructuras , Neoplasias de la Mama/genética , Línea Celular Tumoral , Sistemas de Liberación de Medicamentos/métodos , Femenino , HumanosRESUMEN
This rapid report focuses on the pharmacodynamic mechanism of the carboplatin/paclitaxel combination and correlates it with its cytotoxicity. Consistent with the synergistic to additive antitumor activity (the combination index ranging from 0.53 to 0.94), cells exposed to this combination had significantly increased carboplatin-DNA adduct formation when compared to that of carboplatin alone (450 ± 30 versus 320 ± 120 adducts per 10(8) nucleotides at 2 h, p = 0.004). Removal of paclitaxel increased the repair of carboplatin-DNA adducts: 39.4 versus 33.1 adducts per 10(8) nucleotides per hour in carboplatin alone (p = 0.021). This rapid report provides the first pharmacodynamics data to support the use of carboplatin/paclitaxel combination in the clinic.
Asunto(s)
Carboplatino/metabolismo , Aductos de ADN/metabolismo , Paclitaxel/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/toxicidad , Carboplatino/uso terapéutico , Carboplatino/toxicidad , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Aductos de ADN/uso terapéutico , Aductos de ADN/toxicidad , Sinergismo Farmacológico , Humanos , Paclitaxel/uso terapéutico , Neoplasias de la Vejiga Urinaria/tratamiento farmacológicoRESUMEN
Despite the exciting advances in cancer therapy over past decades, tumor metastasis remains the dominate reason for cancer-related mortality. In present work, DNA-wrapped gold nanorods with doxorubicin (DOX)-loading (GNR@DOX) were developed for treatment of metastatic breast cancer via a combination of chemotherapy and photothermal ablation. The GNR@DOX nanoparticles induced significant temperature elevation and DOX release upon irradiation with near infrared (NIR) light as shown in the test tube studies. It was found that GNR@DOX nanoparticles in combination with laser irradiation caused higher cytotoxicity than free DOX in 4T1 breast cancer cells. Animal experiment with an orthotropic 4T1 mammary tumor model demonstrated that GNR@DOX nanoplatform significantly reduced the growth of primary tumors and suppressed their lung metastasis. The Hematoxylin and Eosin (H&E) and immunohistochemistry (IHC) staining assays confirmed that the tumor growth inhibition and metastasis prevention of GNR@DOX nanoparticles were attributed to their abilities to induce cellular apoptosis/necrosis and ablate intratumoral blood vessels. All these results suggested a considerable potential of GNR@DOX nanoplatform for treatment of metastatic breast cancer.
Asunto(s)
Antibióticos Antineoplásicos/uso terapéutico , Neoplasias de la Mama/terapia , Aductos de ADN/uso terapéutico , Doxorrubicina/uso terapéutico , Oro/uso terapéutico , Neoplasias Pulmonares/prevención & control , Neoplasias Pulmonares/secundario , Nanotubos/química , Animales , Antibióticos Antineoplásicos/administración & dosificación , Mama/efectos de los fármacos , Mama/patología , Neoplasias de la Mama/patología , Línea Celular Tumoral , Aductos de ADN/administración & dosificación , Doxorrubicina/administración & dosificación , Femenino , Oro/química , Humanos , Hipertermia Inducida , Pulmón/efectos de los fármacos , Pulmón/patología , Neoplasias Pulmonares/patología , Ratones Endogámicos BALB C , Ratones Desnudos , Nanotubos/ultraestructura , FototerapiaRESUMEN
The results of Poliplatillen clinical application in 108 patients with advanced pancreatic cancer were analyzed. The use of Poliplatillen in adjuvant regimen improves the long-term results of treatment. The mean survival time was increased on 2.9 months, which was statistically significant, mediana survival was increased on 1.5 months, 10% of patients alived 20 months, 20%--16 months. Survival of patients of control group did not exceed 12 months.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Cisplatino/uso terapéutico , Aductos de ADN/uso terapéutico , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadificación de NeoplasiasRESUMEN
The experience of application of a new antitumoral platinum--containing preparation--polyplatyllen--in the treatment of the small cell pulmonary cancer was summarized. It was established, that the security profile of polyplatyllen is more favourable and efficacy in the treatment of the extended small cell pulmonary cancer is higher, than those of the standard scheme of treatment using cisplatinum and etoposide. The quality of life of the patients, while application of polyplatyllen, is more stable, than in application of the combined prescription of cisplatinum and etoposide.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Células Pequeñas/tratamiento farmacológico , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Carcinoma de Células Pequeñas/cirugía , Cisplatino/administración & dosificación , Cisplatino/efectos adversos , Cisplatino/uso terapéutico , Terapia Combinada , Aductos de ADN/administración & dosificación , Aductos de ADN/efectos adversos , Aductos de ADN/uso terapéutico , Esquema de Medicación , Etopósido/administración & dosificación , Etopósido/efectos adversos , Etopósido/uso terapéutico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
The survival indices of patients suffering gastric cancer stage IV in application of cytostatic preparation polyplatilen were studied up. The most expedient mode of treatment was suggested the conduction of no less than 2 courses of monochemotherapy. As a result, one year had survived (22.53 +/- 4.68)% patients, three years--(7.54 +/- 3.16)%, five years--(4.43 +/- 2.46)%.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Antineoplásicos/uso terapéutico , Cisplatino/uso terapéutico , Aductos de ADN/uso terapéutico , Neoplasias Gástricas , Adenocarcinoma/patología , Adulto , Anciano , Antineoplásicos/administración & dosificación , Cisplatino/administración & dosificación , Aductos de ADN/administración & dosificación , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Gástricas/tratamiento farmacológico , Neoplasias Gástricas/mortalidad , Neoplasias Gástricas/patologíaRESUMEN
In the article authors summarize the experience of new anticancer drug polyplatillen usud in the chemoradiotherapy of small cell lung cancer. Polyplatillen improves the tumor response, general and relapse-free survival of advanced small cell lung cancer treatment in comparance with traditional VEC scheme.
Asunto(s)
Antineoplásicos/uso terapéutico , Carcinoma de Células Pequeñas , Cisplatino/uso terapéutico , Aductos de ADN/uso terapéutico , Neoplasias Pulmonares , Cuidados Paliativos/métodos , Adulto , Anciano , Antineoplásicos/administración & dosificación , Carcinoma de Células Pequeñas/tratamiento farmacológico , Carcinoma de Células Pequeñas/patología , Carcinoma de Células Pequeñas/radioterapia , Cisplatino/administración & dosificación , Aductos de ADN/administración & dosificación , Supervivencia sin Enfermedad , Esquema de Medicación , Femenino , Humanos , Infusiones Intravenosas , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/mortalidad , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/radioterapia , Masculino , Persona de Mediana Edad , Estadificación de NeoplasiasRESUMEN
The authors summarize in the article experience of a new anticancer drug Polyplatillen use in the chemotherapy of advanced pancreatic cancer. Polyplatillen use in the palliative chemotherapy in the patients with advanced pancreatic cancer permits to realize a control of pain and stabilize an ECOG status. Tendency to the improvement of total survival during an early period was registered in the group of patients with advanced pancreatic cancer who were treated with Polyplatillen.
Asunto(s)
Antineoplásicos/uso terapéutico , Cisplatino/uso terapéutico , Aductos de ADN/uso terapéutico , Dolor , Cuidados Paliativos/métodos , Neoplasias Pancreáticas/tratamiento farmacológico , Calidad de Vida , Antineoplásicos/administración & dosificación , Cisplatino/administración & dosificación , Aductos de ADN/administración & dosificación , Humanos , Estado de Ejecución de Karnofsky , Estadificación de Neoplasias , Dolor/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas/psicologíaRESUMEN
Doxorubicin (trade name Adriamycin) is a widely used anticancer agent which exhibits good activity against a wide range of tumors. Although the major mode of action appears to be normally as a topoisomerase II poison, it also exhibits a number of other cellular responses, one of which is the ability to form adducts with DNA. For adduct formation doxorubicin must react with cellular formaldehyde to form an activated Schiff base which is then able to form an aminal (N-C-N) linkage to the exocyclic amino group of guanine residues. The mono-adducts form primarily at G of 5'-GCN-3' sequences where the chromophore of the drug is intercalated between the C and N base pair. The structure of the adducts has have been well defined by 2D NMR, mass spectrometry and X-ray crystallography. The formation of these anthracycline adducts in cells grown in culture has been unequivocally demonstrated. The source of formaldehyde in cells can be endogenous, provided by coadministration of prodrugs that release formaldehyde or by prior complexation of anthracyclines with formaldehyde. Since the adducts appear to be more cytotoxic than doxorubicin alone, and also less susceptible to drug-efflux forms of resistance, they offer new approaches to improving the anticancer activity of the anthracyclines.
Asunto(s)
Antraciclinas/metabolismo , Aductos de ADN/química , Aductos de ADN/metabolismo , Doxorrubicina/química , Doxorrubicina/metabolismo , Modelos Moleculares , Neoplasias/tratamiento farmacológico , Aductos de ADN/uso terapéutico , Doxorrubicina/uso terapéutico , Formaldehído/metabolismo , Humanos , Profármacos/metabolismoRESUMEN
Oxaliplatin (Eloxatin), a recently developed third-generation cisplatin analogue with a 1,2-diaminocyclohexane (DACH) carrier ligand, has displayed preclinical and clinical activity in a wide variety of tumour types. Synergistic with 5-FU in colorectal cancer (CRC), the combination has proven efficacy in 5-FU-resistant advanced disease and in previously untreated CRC, as demonstrated in controlled phase III trials, while evaluation in the adjuvant setting is ongoing. Due to its excellent safety profile, its unique mechanism of action and lack of cross-resistance with other active agents in CRC, oxaliplatin has also been combined with CPT-11 and Raltitrexed with promising results. Trials in pretreated and untreated advanced ovarian cancer (AOC), as a single agent or in combination with cisplatin, cyclophosphamide or paclitaxel, indicate a yet to be defined role in AOC and confirm its lack of cross-resistance with cis/carboplatin. Clinical investigations of single agent and combination therapies in breast, lung, prostate and germ-cell carcinomas, non-Hodgkin's lymphoma and malignant mesothelioma are being pursued. While the role of oxaliplatin in medical oncology is yet to be fully defined, it appears to be an important new anticancer agent.