A case report of a severe fluoropyrimidine-related toxicity due to an uncommon DPYD variant.

INTRODUCTION: Fluoropyrimidines such as 5-fluorouracil (5-FU) and its orally active prodrug, capecitabine, are widely used in the treatment of gastrointestinal cancer, including colorectal cancer. Dihydropyrimidine dehydrogenase (DPD) plays an important role in the 5-FU metabolism. Dihydropyrimidine dehydrogenase gene (DPYD) is a highly polymorphic gene with several hundreds of reported genetic variants and DPD activity levels vary considerably among individuals, with different 5-FU-related efficacy and toxicity. About 5% of the population is deficient in DPD enzyme activity. The most well studied DPYD variant is the IVS14+1G>A, also known as DPYD *2A. In this report, we present a case of a patient with a double heterozygote DPYD variant (DPYD activity score: 0,5 according to Clinical Pharmacogenetics Implementation Consortium) who experienced a severe fluoropyrimidine-related toxicity resolved without any consequence. PATIENT CONCERNS: A 46-years-old Caucasian man with diagnosis of left colon adenocarcinoma underwent left hemicolectomy on July 2017: pT3 G3 N1c M0. According to the disease stage, he started an adjuvant therapy with XELOX using capecitabine at 50% of total dose, because of his DPYD IVS14+1G>A variant, detected before the treatment. DIAGNOSIS: After few days, despite of this dose reduction, he experienced life-threatening adverse events such as mucositis G3, diarrhea G3, neutropenia G4, thrombocytopenia G4, and hyperbilirubinemia G3 according to Common Terminology Criteria for Adverse Events v 5.0. INTERVENTIONS: As first, we set up an intensive rehydration therapy, antibiotic and antifungal prophylaxis, Granulocyte-Colony Stimulating Factors, and supportive blood transfusions. Additional genetic tests revealed a double heterozygote variant of DPYD gene (DPYD IVS14+1G>A and 2846A>T) which is a very rare situation and only 3 cases are described in literature, all of them concluded with patient's death. OUTCOMES: After 3 weeks of intensive therapy, the patient was fully recovered. Furthermore, all the whole-body CT scans performed since discharge from the hospital until now, have confirmed no evidence of disease. CONCLUSIONS: Recent studies demonstrated that screening strategy for the most common DPYD variants allowed for avoiding toxicities and saving money. This report underlines the importance of genotyping DPYD before treatment and emphasizes the role of genotype-guided dose individualization.

Acute and delayed toxicity of gemcitabine administered during isolated lung perfusion: a preclinical dose-escalation study in pigs.

OBJECTIVES: Colorectal cancer is the third most commonly diagnosed cancer worldwide, with up to 25% of patients presenting with metastases at the time of diagnosis. Despite pulmonary metastasectomy many patients go on to develop pulmonary recurrence, which might be linked to the presence of lung micrometastases. In this setting, the adjuvant administration of high-dose chemotherapy by isolated lung perfusion (ILP) has shown encouraging results. However, the tolerance to and efficacy of modern gemcitabine (GEM)-based chemotherapy regimens during adjuvant ILP remain unknown. We conducted a dose-escalating preclinical study to evaluate the immediate and delayed toxicity of GEM in a pig model to define dose-limiting toxicity (DLT) and maximum tolerated concentration. METHODS: Twenty-three pigs were given increasing concentrations of GEM during ILP, and were awakened at the end of the procedure. The concentrations of GEM were 40, 80, 160, 320, 640 and 1280 µg/ml. Serum and lung samples were taken to measure GEM concentrations. Pulmonary damage was evaluated by histological examination and cleaved caspase-3 detection. Immediate and delayed (1 month) toxicity were recorded. RESULTS: All of the animals underwent successful ILP with GEM. No systemic leak was observed. The three pigs that received a concentration of GEM of 1280 µg/ml died of hypoxia after lung recirculation at the end of the procedure. Eleven pigs survived for 1 month. Major lung toxicity was observed for the concentration of GEM of 640 µg/ml, both at the end of the procedure and after 1 month. DLT was defined at the concentration of 640 µg/ml and the maximum tolerated dose (MTD) was defined at the concentration of 320 µg/ml. CONCLUSIONS: ILP with GEM is a safe and reproducible technique in this large-animal model, which includes 1 month of survival. The MTD in this pig model was a concentration of GEM of 320 µg/ml.

Synergistic cytotoxic activity of treosulfan and gemcitabine in pancreatic cancer cell lines.

BACKGROUND: Treatment for advanced pancreatic cancer is still very unsatisfactory. Treosulfan is an alkylating agent used for conventional, as well as high-dose chemotherapy regimens, whereby plasma concentrations over 500 µg/ml can be achieved. We investigated the effects of treosulfan on pancreatic cancer cell lines. MATERIALS AND METHODS: Using Panc-1, MIA PaCa-2 and Capan-2 cell lines, we investigated the in vitro cytotoxicity of treosulfan-alone and in combination with gemcitabine, 5-fluorouracil or irradiation. RESULTS: Treosulfan was potently cytotoxic against all pancreatic cancer cell lines at all concentrations (1-100 µg/ml). Combination of treosulfan and gemcitabine revealed strong synergistic effects independent of the sequence of drug administration. Similarly, synergism was observed with irradiation. Combination of treosulfan and 5-fluorouracil revealed antagonism. CONCLUSION: Treosulfan effectively kills pancreatic carcinoma cells in vitro and has synergistic activity in combination with gemcitabine and irradiation. These results warrant further investigation of treosulfan in the treatment of pancreatic cancer.

Ursolic acid inhibits growth and metastasis of human colorectal cancer in an orthotopic nude mouse model by targeting multiple cell signaling pathways: chemosensitization with capecitabine.

PURPOSE: Development of chemoresistance, poor prognosis, and metastasis often renders the current treatments for colorectal cancer (CRC) ineffective. Whether ursolic acid, a component of numerous medicinal plants, either alone or in combination with capecitabine, can inhibit the growth and metastasis of human CRC was investigated. EXPERIMENTAL DESIGN: The effect of ursolic acid on proliferation of CRC cell lines was examined by mitochondrial dye uptake assay, apoptosis by esterase staining, NF-κB activation by DNA-binding assay, and protein expression by Western blot. The effect of ursolic acid on the growth and chemosensitization was also examined in orthotopically implanted CRC in nude mice. RESULTS: We found that ursolic acid inhibited the proliferation of different colon cancer cell lines. This is correlated with inhibition of constitutive NF-κB activation and downregulation of cell survival (Bcl-xL, Bcl-2, cFLIP, and survivin), proliferative (cyclin D1), and metastatic (MMP-9, VEGF, and ICAM-1) proteins. When examined in an orthotopic nude mouse model, ursolic acid significantly inhibited tumor volume, ascites formation, and distant organ metastasis, and this effect was enhanced with capecitabine. Immunohistochemistry of tumor tissue indicated that ursolic acid downregulated biomarkers of proliferation (Ki-67) and microvessel density (CD31). This effect was accompanied by suppression of NF-κB, STAT3, and ß-catenin. In addition, ursolic acid suppressed EGF receptor (EGFR) and induced p53 and p21 expression. We also observed bioavailability of ursolic acid in the serum and tissue of animals. CONCLUSION: Overall, our results show that ursolic acid can inhibit the growth and metastasis of CRC and further enhance the therapeutic effects of capecitabine through the suppression of multiple biomarkers linked to inflammation, proliferation, invasion, angiogenesis, and metastasis.

Cytidine deaminase single-nucleotide polymorphism is predictive of toxicity from gemcitabine in patients with pancreatic cancer: RTOG 9704.

The aim of this study is to validate the prognostic and predictive value of the non-synonymous cytidine deaminase (CDA) Lys²7Gln polymorphism for hematological toxicity and survival using a randomized phase III adjuvant trial (Radiation Therapy Oncology Group (RTOG) 9704) in pancreatic cancer in which one treatment arm received gemcitabine. CDA is involved in gemcitabine inactivation, and there is conflicting data on the role of the non-synonymous CDA Lys²7Gln polymorphism in predicting toxicity and survival in cancer patients treated with gemcitabine. RTOG 9704 randomized 538 patients after pancreatic resection to receive radiotherapy with either 5-fluorouracil (5-FU) or gemcitabine. CDA Lys²7Gln polymorphism genotype was analyzed. We tested an association between CDA single-nucleotide polymorphism genotype and the survival outcome by the Cox proportional hazard model adjusting for other covariates, as well as toxicity by the logistic regression model. There is statistically significant more severe hematological toxicity in patients treated with gemcitabine with either the homozygote wild-type genotype (Lys/Lys) alone (odds ratio (OR)=0.06, P=0.01), or in combination with the heterozygote (Lys/Gln; OR=0.14, P=0.03) when compared with homozygote variant genotype (Gln/Gln) when adjusted for other covariates. This was not seen in the non-gemcitabine treated arm. There are no genotype differences with respect to survival outcome. In conclusion, in this prospective randomized adjuvant study of patients with pancreatic cancer, the CDA Lys²7Gln polymorphism is validated as a predictive marker of gemcitabine hematological toxicity, but not with treatment response or survival.

Pulmonary toxicity with oxaliplatin and capecitabine/5-Fluorouracil chemotherapy: a case report and review of the literature.

BACKGROUND: Oxaliplatin in combination with either 5-fluorouracil or capecitabine is commonly used in the treatment of colorectal cancer and is rarely associated with pulmonary toxicity. This is the first reported case of oxaliplatin and capecitabine/5-fluorouracil causing pulmonary toxicity in a patient with pre-existing asymptomatic interstitial lung disease. CASE REPORT: We report a case of a man who was treated with oxaliplatin and capecitabine for 1 cycle, then subsequently with oxaliplatin and 5-fluorouracil following a resected Dukes' C colon carcinoma. His preoperative computed tomography scan incidentally showed mild pulmonary interstitial changes for which he was asymptomatic. He developed pulmonary fibrosis during the course of his chemotherapy, and therefore further chemotherapy was stopped. He was treated with high dose steroids and immunosuppressants which initially stabilized his respiratory symptoms. CONCLUSIONS: Pulmonary fibrosis is a rare complication of oxaliplatin and capecitabine/5-fluorouracil. With the widespread use of oxaliplatin combinations in colorectal cancer, active assessment for interstitial lung disease is recommended and caution in its use should be exercised in those with pre-existing interstitial lung disease.

Honokiol arrests cell cycle, induces apoptosis, and potentiates the cytotoxic effect of gemcitabine in human pancreatic cancer cells.

Survival rates for patients with pancreatic cancer are extremely poor due to its asymptomatic progression to advanced and metastatic stage for which current therapies remain largely ineffective. Therefore, novel therapeutic agents and treatment approaches are desired to improve the clinical outcome. In this study, we determined the effects of honokiol, a biologically active constituent of oriental medicinal herb Magnolia officinalis/grandiflora, on two pancreatic cancer cell lines, MiaPaCa and Panc1, alone and in combination with the standard chemotherapeutic drug, gemcitabine. Honokiol exerted growth inhibitory effects on both the pancreatic cancer cell lines by causing cell cycle arrest at G1 phase and induction of apoptosis. At the molecular level, honokiol markedly decreased the expression of cyclins (D1 and E) and cyclin-dependent kinases (Cdk2 and Cdk4), and caused an increase in Cdk inhibitors, p21 and p27. Furthermore, honokiol treatment led to augmentation of Bax/Bcl-2 and Bax/Bcl-xL ratios to favor apoptosis in pancreatic cancer cells. These changes were accompanied by enhanced cytoplasmic accumulation of NF-κB with a concomitant decrease in nuclear fraction and reduced transcriptional activity of NF-κB responsive promoter. This was associated with decreased phosphorylation of inhibitor of kappa B alpha (IκB-α) causing its stabilization and thus increased cellular levels. Importantly, honokiol also potentiated the cytotoxic effects of gemcitabine, in part, by restricting the gemcitabine-induced nuclear accumulation of NF-κB in the treated pancreatic cancer cell lines. Altogether, these findings demonstrate, for the first time, the growth inhibitory effects of honokiol in pancreatic cancer and indicate its potential usefulness as a novel natural agent in prevention and therapy.

Combined environmental risk assessment for 5-fluorouracil and capecitabine in Europe.

An environmental risk assessment (ERA) was made for the old cytostatic active pharmaceutical ingredient 5-fluorouracil (5-FU) and for capecitabine (CAP), which is a prodrug of 5-FU. This ERA is based on published and company internal data as well as new test results for physicochemical, human metabolism, biodegradability, environmental partitioning and fate, and acute and chronic ecotoxicity properties of the active substance 5-FU as well as on use sales data for 5-FU and CAP in Europe. Predicted environmental concentrations (PECs) were extrapolated following the EMEA 2006 Guideline on ERA for human pharmaceuticals and the European Union 2003 Technical Guidance Document (TGD) for risk assessment as well as the TGD-based application EUSES v2.0. Actual amounts sold were taken from IMS Health Databases, in order to refine the default use and EMEA penetration factor as well as the PECs. Moreover, available measured environmental concentrations (MECs) were used to supplement PECs. A predicted no-effect concentration (PNEC) for 5-FU was derived from chronic ecotoxicity data. Except for the simplistic EMEA Phase I default PEC, the risk characterization by PEC:PNEC and MEC:PNEC ratios for various environmental compartments resulted in no significant risk. As the EMEA Phase I PEC does not integrate documented human metabolism and environmental degradation, in contrast to refined PEC derivations, it is inferred that the current use of CAP and 5-FU does not present any evident risk to the environment. An additional evaluation of persistence, bioaccumulation, and toxicity (PBT) properties supports the conclusion of no significant environmental risk for 5-FU and CAP.

Phase I study of oxaliplatin in combination with capecitabine and radiotherapy as postoperative treatment for stage II and III rectal cancer.

PURPOSE: A Phase I study was conducted to determine the maximal tolerated dose and the dose-limiting toxicity (DLT) of oxaliplatin (OXA) combined with capecitabine and radiotherapy as adjuvant treatment in patients with operable rectal cancer. PATIENTS AND METHODS: A total of 21 patients with Stage II or III rectal adenocarcinoma after curative surgery were treated with radiotherapy to a total dose of 50 Gy in 5 weeks. OXA was administered at a dosage of 40 (n = 6), 50 (n = 3),60 (n = 3), 70 (n = 3), or 80 mg/m(2) (n = 6) once a week for 2 weeks (first cycle) followed by a second cycle after a 7-day break. Capecitabine at a fixed dose of 1,300 mg/m(2)/d was administered orally at the same schedule as for OXA. DLT was defined as Grade 3 or 4 hematologic and nonhematologic toxicity. RESULTS: Grade 1-3 leukopenia, diarrhea, and nausea/vomiting were the most common toxic side effects, and most were Grade 1-2. A DLT was first observed in 1 of 3 patients at 40 mg/m(2) (Grade 3 diarrhea) but was not observed in the next 3 patients at the same level or in patients who received a dose level of 50-70 mg/m(2). At 80 mg/m(2), DLT occurred in 3 of 6 patients (1 Grade 4 leukopenia and 2 Grade 3 diarrhea). CONCLUSIONS: OXA combined with a fixed dose of capecitabine at 625 mg/m(2) twice daily by mouth plus radiotherapy in the adjuvant setting was tolerable and clinically feasible. The maximal tolerated dose of OXA in this setting was 80 mg/m(2), comparable to the maximal tolerated dose of OXA in the neoadjuvant setting.

Preclinical toxicology (subacute and acute) and efficacy of a new squalenoyl gemcitabine anticancer nanomedicine.

This study investigates 1) the anticancer efficacy of a new squalenoyl prodrug of gemcitabine (SQgem) in nanoassembly form compared with gemcitabine at equitoxic doses and 2) the subacute and acute preclinical toxicity of these compounds. The toxicity studies revealed that SQgem nanoassemblies, like gemcitabine, were toxic, and they led to dose-dependent mortality after daily i.v. injections for 1 week, irrespective of the route of administration. However, a 4- to 5-day spaced dosing schedule (injections on day 0, 4, 8, and 13) was proved to be safer in terms of weight loss and hematological and other toxicity. Using this spaced dosing schedule, SQgem nanoassemblies exhibited impressive anticancer activity in mice bearing L1210 leukemia because this treatment led to 75% long-term survivors. In contrast, at equitoxic doses, neither free gemcitabine nor cytarabine led to longterm survivors and all the mice of these groups died of the disease. Further toxicity studies performed at lethal doses by blood and serum analysis and organ weight determinations revealed that the hematological toxicity was the dose-limiting toxicity in both SQgem nanoassemblies and gemcitabine, whereas probable gastrointestinal toxicity was also associated with free gemcitabine. The SQgem nanoassemblies did not display hepatotoxicity, which is one of the clinically encountered toxicities of gemcitabine. To summarize, these preclinical studies demonstrated that the toxicological profile of new squalenoyl gemcitabine nanomedicine was not distinct from that of the parent gemcitabine, whereas it was much more potent than gemcitabine at equitoxic doses and cytarabine at clinically relevant doses. These data support the candidature of SQgem for clinical trials.

Effect of dose regimen on the toxicity of 2'-deoxy-2'-methylidenecytidine (DMDC) in monkeys.

2'-deoxy-2'-methylidenecytidine (DMDC) is a potential anticancer deoxycytidine analog of cytosine arabinoside. Using monkeys, we conducted a 4-week toxicity study with toxicokinetics of DMDC at 1, 3, and 10 mg/kg/day and a dose-regimen study of three different schedules of once-daily administration (5 mg/kg/day) for 1 week every 2 weeks, 2 weeks every 4 weeks, and 3 weeks every 4 weeks. Deaths, myelosuppression, intestinal toxicity, and swelling of palm and sole skin were observed by oral DMDC treatment at 10 mg/kg/day in 4-week repeated toxicity study; however, no skin disorders have been reported in humans. No notable changes were observed at 1 and 3 mg/kg/day. The curves of dose vs. AUC and the AUC at MTD in monkey are similar to those in humans. In the dose-regimen study, all the toxicities were reversible but more severe toxicity was observed with the longer administration periods. One-week interruption showed sufficient recovery of decreased WBC in dosing regimens of 1-week-on/1-week-off and 2-weeks-on/2-weeks-off. A 2-week recovery period was almost sufficient for the recovery of decreased RBC, HCT, and skin disorders in the 2-weeks-on/2-weeks-off regimen. Therefore, once-daily for 2 weeks every 4 weeks was concluded to be the optimal dose regimen. In summary, myelosuppression, intestinal toxicity, and skin disorders were observed in DMDC treatment in monkeys, the relationship between AUC and toxicity in monkeys was close to that in humans, and in preclinical studies, it is advantageous to investigate optimal dose regimens using the appropriate species.

A phase II study of second-line neoadjuvant chemotherapy with capecitabine and radiation therapy for anthracycline-resistant locally advanced breast cancer.

OBJECTIVE: According to data from Brazil's National Cancer Institute nearly 30% of the new patients who present with breast cancer have locally advanced disease. These patients are inoperable and tumor reduction is usually attempted with chemotherapy. First-line anthracyclin-based neoadjuvant chemotherapy is often effective; however, about 30% of the patients fail and to date there is no established second-line treatment. We have studied the concomitant use of radiation therapy and capecitabine in this setting, to determine the toxicity and efficacy of this regimen as a second-line neoadjuvant treatment. PATIENTS AND METHODS: Twenty-eight patients with inoperable locally advanced breast cancer refractory to first-line anthracycline based treatment were enrolled between January 2003 and May 2004. Patients received radiation therapy (total dose 5000 cGy) and concomitant capecitabine (850 mg/m2) twice daily for 14 days every 3 weeks. RESULTS: This treatment rendered 23 of the 28 patients (82%) operable. The 5 remaining patients did not undergo surgery because of disease progression. The median clinical tumor size decreased from 80 cm2 to 49 cm2. Microscopic residual disease was observed in 3 patients (13%) and another patient achieved a complete pathologic response. The median number of involved lymph nodes was 2 and treatment was well tolerated with no grade 3 or 4 events. CONCLUSION: Our data indicate that second-line neoadjuvant treatment with radiation therapy and capecitabine is feasible, well tolerated, and effective in patients with locally advanced breast cancer refractory to primary anthracycline-based treatment. These results suggest that a randomized study should be done to compare radiotherapy alone to capecitabine combined with radiotherapy.

Dendritic cell-mediated cross-presentation of antigens derived from colon carcinoma cells exposed to a highly cytotoxic multidrug regimen with gemcitabine, oxaliplatin, 5-fluorouracil, and leucovorin, elicits a powerful human antigen-specific CTL response with antitumor activity in vitro.

Gemcitabine, oxaliplatin, leucovorin, and 5-fluorouracil (GOLF) is a novel multidrug regimen inducing high levels of necrosis and apoptosis in colon carcinoma cells. This regimen is also able to promote a process of Ag remodeling including up-regulation of immunotherapy targets like carcinoembryonic Ag (CEA), thymidylate synthase (TS). We have conducted a preclinical study aimed to investigate whether these drug-induced modifications would also enhance colon cancer cell immunogenicity. Several CTL lines were thus generated by in vitro stimulating human HLA-A(*)02.01(+) PBMCs, from normal donors and colon cancer patients, with autologous dendritic cells cross-primed with cell lysates of colon cancer cells untreated, irradiated, or previously exposed to different drug treatments including the GOLF regimen. Class I HLA-restricted cytolytic activity of these CTL lines was tested against colon cancer cells and CEA and TS gene transfected target cells. These experiments revealed that CTLs sensitized with GOLF-treated cancer cells were much more effective than those sensitized with the untreated colon carcinoma cells or those exposed to the other treatments. CTL lines sensitized against the GOLF-treated colon cancer cells, also expressed a greater percentage of T-lymphocyte precursors able to recognize TS- and CEA-derived peptides. These results suggest that GOLF regimen is a powerful antitumor and immunomodulating regimen that can make the tumor cells a suitable means to induce an Ag-specific CTL response. These results suggest that a rationale combination of GOLF chemotherapy with cytokine-based immunotherapy could generate a chemotherapy-modulated Ag-specific T-lymphocyte response in cancer patients able to destroy the residual disease survived to the cytotoxic drugs.

Phase II study of pemetrexed-gemcitabine combination in patients with advanced-stage non-small cell lung cancer.

PURPOSE: Cisplatin is one of the most active agents for the treatment of non-small cell lung cancer (NSCLC). It is also known for significant toxicity, which makes it unsuitable for certain patients. Our purpose was to evaluate the efficacy and toxicity of a promising cisplatin-free combination, gemcitabine plus pemetrexed, in NSCLC. EXPERIMENTAL DESIGN: Chemo-naive patients with inoperable NSCLC were eligible for this study. Gemcitabine (1250 mg/m2) was given intravenously on days 1 and 8, followed by intravenous pemetrexed (500 mg/m2) on day 8. After inclusion of 13 patients, folic acid and vitamin B12 supplementation was added to lower pemetrexed-induced toxicity. Quality of life was assessed with the Lung Cancer Symptom Scale. RESULTS: Sixty patients enrolled; 58 were evaluable for response. All patients had a World Health Organization performance status of 0 or 1. Eighty-seven percent had stage IV disease. Nine patients had a confirmed partial response [overall response rate, 15.5%; 95% confidence interval (CI), 7.3-27.4%]. Twenty-nine (50.0%) patients had stable disease. Median overall survival was 10.1 months (95% CI, 7.9-13.0 months), with a 1- and 2-year overall survival of 42.6% (95% CI, 30.0-55.3%) and 18.5% (95% CI, 7.9-29.1%). Median progression-free survival was 5.0 months. Median response duration was 3.3 months. There were no deaths attributed to treatment. Common Toxicity Criteria grade 3/4 toxicities were neutropenia (61.7%), febrile neutropenia (16.7%), fatigue (23.3%), and elevations of aspartate aminotransferase (15.0%) and alanine aminotransferase (20.0%). CONCLUSIONS: This combination had good tolerance and achieved promising overall survival with extended 1- and 2-year survival rates. This cisplatin-free regimen warrants further evaluation in randomized trials.

Experimental study on the toxicity and the local and systemic tolerability of gemcitabine after topical treatment of the rabbit bladder.

This study investigated gemcitabine administered intravesically to establish the local and systemic tolerability necessary for clinical trials. Gemcitabine was directly administered via catheter into the bladders of 24 male New Zealand rabbits weighing an average of 1.9+/-0.08 kg. Three groups received weekly gemcitabine for 5 (50 mg/kg) or 8 (25 mg/kg or controls) weeks. Animals were inspected daily for signs of toxicity and distress, body weight changes, and water and food consumption; electrocardiogram, blood pressure, and urinalysis were recorded before dosing and after 4 and 8 weeks of treatment. The rabbits were euthanized, and a full necropsy was performed on day 1 after the last instillation. Principal organs (spleen, thymus, testis, and muscle) and plasma samples were analyzed for the systemic absorption of gemcitabine. The 25-mg/kg dose was well tolerated with no clinical side effects. At 50 mg/kg, signs of mild myelosuppression and severe symptomatic toxicity (leg weakness, and hair and body weight loss) was evident after 3 weeks of treatment and three of the seven animals in this group died after four doses. Necropsies revealed normal bone marrow cellularity and organ histology at both doses. No significant systemic drug absorption was seen. These findings suggest that intravesical administration of gemcitabine does not produce organ-specific toxicity, but the higher dose (50 mg/kg) may represent the threshold above which increasing morbidity may occur.

Combination effects of alkylphosphocholines and gemcitabine in malignant and normal hematopoietic cells.

Cytosine arabinoside (ara-C) and 2',2'-difluorodeoxycytidine (Gem) were compared in leukemia cells, with Gem being more potent than ara-C. Gem was combined with hexadecylphosphocholine (HPC) or erucylphospho-N,N,N-trimethylpropanolamine (ErPC(3)) in resistant CML cells. Supra-additive effects were seen in K-562 cells after concomitant and sequential exposure of Gem followed by HPC. The reverse sequence resulted in antagonism. Both effects were more significant when HPC was exchanged for ErPC(3). Gem or HPC failed to induce DNA laddering in K-562 cells, but apoptotic signals were transferred by the Gem-exposed SKW-3 cytosolic fraction to K-562 nuclei. HPC did not increase the clastogenicity of Gem and counteracted its mitotic inhibition in murine bone marrow. Thus, the combination of Gem and an alkylphosphocholine is advantageous in terms of their complementary mode of action, resulting in increased cytotoxicity and lowered myelotoxicity.

Capecitabine, a new oral fluoropyrimidine for the treatment of colorectal cancer.

Capecitabine (Xeloda)(R) was developed as a tumour-selective fluoropyrimidine carbamate to achieve higher intratumoural 5-FU level and lower toxicity than 5-FU. Capecitabine passes unchanged through the gastrointestinal tract and is metabolised in the liver to 5'-deoxy-5-fluorocytidine (5'-DFCR). Here it is converted to doxifluridine (5'-DFUR) and finally, 5'-DFUR is metabolised by thymidine phosphorilase to 5-FU at the tumour site. Preclinical studies have demonstrated capecitabine's activity in both 5-FU-sensitive and 5-FU-resistant tumours. In a randomised phase II trial in advanced colorectal cancer the recommended dose and schedule of Capecitabine is 2.510 mg/m(2)/day (total dose divided into two equal morning and evening doses) given in an intermittent schedule (2 weeks on/1 week off). Phase III trials in patients with advanced colorectal cancer show a better response rate than the Mayo Clinic schedule, with no differences in terms of DR, PFS. Diarrhoea and hand-foot syndrome were the principal grade 3/4 toxicities noted, occurring in 10% and 16% of patients, respectively. The selectivity of this drug opens an important prospective in the treatment of colorectal cancer in advanced and adjuvant setting.

Toxicology and pharmacokinetics of intravesical gemcitabine: a preclinical study in dogs.

More active and well-tolerated agents are needed for the treatment of superficial bladder cancer. This study investigated intravesical gemcitabine to establish the toxicology and pharmacokinetics necessary for clinical trials. Beagle dogs (in groups of 2; n = 6) received 100 mg, 350 mg, or 1 g of drug by intravesical administration on alternate days three times/week for 4 weeks. Animals were observed for clinical signs of toxicity; gemcitabine levels and peripheral blood counts were taken three times weekly. The dogs were euthanized, and a full necropsy was performed at days 1 and 14 after the last dose. Intravesical gemcitabine was given at 100 mg (n = 2), 350 mg (equivalent to the 1000 mg/m2 human dose; n = 3), and 3.5 g (n = 1). i.v. gemcitabine was given at 350 mg (n = 2). Plasma samples drawn at time points up to 8 h were analyzed for systemic absorption and clearance of drug. Doses of 100 and 350 mg were well tolerated with no clinical side effects. Necropsies revealed normal bone marrow cellularity and normal bladder histology. At 1 g, signs of severe clinical toxicity were evident, and after only three doses, necropsies demonstrated severe bone marrow hypoplasia, cystitis, and intestinal necrosis. At all intravesical doses, significant systemic absorption was seen. The T1/2 (+/- SD) for intravesical and i.v. administration of 350 mg was 328 (+/-6.8) min and 99.3 (+/-5.2) min, respectively (P<0.001). Intravesical gemcitabine is well tolerated and has no direct bladder toxicity at doses up to 1000 mg/m2. Higher doses result in gastrointestinal, bladder, and bone marrow toxicity.

Evaluation of the antitumor activity of gemcitabine (2',2'-difluoro-2'-deoxycytidine).

A new pyrimidine antimetabolite, 2',2'-difluorodeoxycytidine, Gemcitabine (LY188011, dFdCyd) has been synthesized and evaluated in experimental tumor models. dFdCyd is a very potent and specific deoxycytidine analogue. The concentration required for 50% inhibition of growth is 1 ng/ml in the CCRF-CEM human leukemia cell culture assay. Concurrent addition of deoxycytidine to the cell culture system provides about a 1000-fold decrease in biological activity. The inhibition of growth of human leukemia cells in culture led to the in vivo evaluation of this compound as a potential oncolytic agent. Maximal activity in vivo was seen with dFdCyd when administered on an every third day schedule. 1-beta-D-Arabinofuranosylcytosine, administered on a daily for 10-day schedule, was directly compared to dFdCyd in this evaluation. dFdCyd demonstrated good to excellent antitumor activity in eight of the eight murine tumor models evaluated. 1-beta-D-Arabinofuranosylcytosine was substantially less active or had no activity in these same tumor models. This in vivo activity against murine solid tumors supports the conclusion that dFdCyd is an excellent candidate for clinical trials in the treatment of cancer.

Comparison of the cellular pharmacokinetics and toxicity of 2',2'-difluorodeoxycytidine and 1-beta-D-arabinofuranosylcytosine.

2',2'-Difluorodeoxycytidine (dFdC) is a new deoxycytidine analogue with good activity against human leukemic cell lines and murine solid tumors, while the activity of 1-beta-D-arabinofuranosylcytosine (ara-C) is established in experimental systems and for the treatment of human adult leukemia. This study compared the cellular metabolism and cytotoxic properties of dFdC and ara-C in Chinese hamster ovary cells. In wild-type cells, dFdC was significantly more cytotoxic than ara-C after both 4- and 18-h incubations. The 5'-triphosphate of dFdC (dFdCTP) was the major cellular metabolite (85-90%), reaching cellular concentrations up to 20-fold greater than those observed for ara-C 5'-triphosphate at equimolar concentrations of the parent drug. A deoxycytidine kinase-deficient mutant neither accumulated dFdCTP nor showed any cytotoxic response up to drug concentrations of 100 microM. The cytotoxicity of dFdC could be competitively reversed by deoxycytidine further suggesting that dFdC, like ara-C, required phosphorylation by deoxycytidine kinase for biological activity. Several explanations for the different cellular accumulation of the drug triphosphates were established: (a) nucleoside transport studies demonstrated that the membrane permeation of dFdC was 65% more rapid than that of ara-C; (b) deoxycytidine kinase had a higher affinity for dFdC (Km = 3.6 microM) than for ara-C (Km = 8.8 microM), while the Km for deoxycytidine was 1.4 microM; (c) the elimination of intracellular dFdCTP was biphasic with t1/2 alpha = 3.9 and t1/2 beta greater than 16 h while the degradation of ara-CTP was monophasic and significantly faster (t1/2 = 0.7 h). The comparatively long half-life of dFdCTP was related to the prolonged inhibition of DNA synthesis after removal of exogenous nucleoside. Together these factors contribute to the more potent cytotoxicity of dFdC compared with ara-C.