Bortezomib plus docetaxel in advanced non-small cell lung cancer and other solid tumors: a phase I California Cancer Consortium trial

BACKGROUND

This phase I study was performed to determine the dose-limiting toxicity and maximum tolerated dose (MTD) of docetaxel in combination with bortezomib in patients with advanced non-small cell lung cancer (NSCLC) or other solid tumors.

METHODS

Patients were enrolled in cohorts of three over six dose levels. Each treatment cycle was 3 weeks long and consisted of one docetaxel infusion (day 1) and four bortezomib injections (days 1, 4, 8, and 11). Dose escalation and MTD determination were based on the occurrence of dose-limiting toxicities in cycle 1 only.

RESULTS

A total of 36 patients were enrolled, 26 of whom had NSCLC. All patients received at least one dose of study drug at one of five dose levels. The MTD of the combined regimen was determined to be 1.0/75 mg/m bortezomib/docetaxel. The combination was generally well tolerated. Toxicities were manageable, and no additive toxicities were observed. The most common adverse events were fatigue (67% of patients), nausea (50%), diarrhea (39%), and neutropenia (39%). Two patients with NSCLC achieved a partial response, and seven (19%) patients achieved stable disease (including six patients with NSCLC).

CONCLUSION

The combination of bortezomib and docetaxel was feasible and well tolerated in patients with advanced NSCLC or other solid tumors. The recommended phase II dose is bortezomib 1.0 mg/m on days 1, 4, 8, and 11 plus docetaxel 75 mg/m on day 1, cycled every 21 days. Therapeutic doses of docetaxel and bortezomib are achievable for this combination.

Phase I clinical trial of weekly docetaxel and exisulind, a novel inducer of apoptosis

BACKGROUND

The objective of this phase I study was to determine the maximal tolerated dose (MTD) of the combination of weekly docetaxel and exisulind in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients with advanced or refractory solid tumors were treated with intravenous weekly docetaxel with daily oral exisulind. The following dose levels (docetaxel/exisulind) were explored: 30-mg/m2/200 mg po bid, 35/200, 35/250 and 40/250. Docetaxel was administered weekly for 6 weeks followed by 2 weeks off, and exisulind was taken twice daily. Each cycle was 8 weeks.

RESULTS

Eighteen patients were enrolled in the study. All of them had received prior systemic therapy. Most patients had either melanoma or carcinomas of the upper gastrointestinal tract. A total of 31 cycles of therapy were administered. DLTs were grade 3 diarrhea, anorexia and fatigue and grade 3 cutaneous toxicity at dose level 4 (40/250). Myelosuppression was mild. Fatigue and gastrointestinal toxicity (anorexia, dyspepsia, nausea, abdominal pain and diarrhea) represented the most common toxicities. However, grade 3 and grade 4 toxicities were uncommon. There were no treatment related deaths. No objective responses were observed and five patients achieved stable disease.

CONCLUSIONS

The recommended dose for phase II studies is weekly docetaxel 35 mg/m2 for 6 weeks followed by 2 weeks off in combination with oral exisulind 250 mg po bid. This combination is feasible and well-tolerated at these doses.

Intermittent dosing of the farnesyl transferase inhibitor tipifarnib (R115777) in advanced malignant solid tumors: a phase I California Cancer Consortium Trial

Tipifarnib (R115777) inhibits farnesylation of key proteins that modulate signaling pathways implicated in cell growth and proliferation, including members of the Ras and Rho families. It has broad-spectrum antiproliferative activity in vitro and in vivo. Clinical trials employing a continuous administration schedule have demonstrated dose-limiting neurotoxicity and myelosuppression. Preclinical studies have shown that intermittent oral administration can suppress tumor growth comparable to continuous administration. We conducted a National Cancer Institute-sponsored phase I trial to determine the feasibility of an intermittent dosing schedule of R115777 given orally twice daily on weeks 1 and 3 of a 28-day cycle in patients with malignant solid tumors. Starting dose was 300 mg twice daily (b.i.d.) with escalation by 300 mg b.i.d. increments over six dose levels to a maximum of 1800 mg b.i.d. Dose-limiting toxicity (DLT) was defined as any grade 3 or 4 non-hematologic toxicity, grade 4 thrombocytopenia, grade 4 neutropenia (ANC) with fever (38.3 degrees C or above) or a documented infection. Twenty-one patients with advanced solid tumors, all of whom had prior systemic therapy, were accrued. Grade 3 fatigue was dose limiting for two of three patients at the 900 mg b.i.d. dose level. Although no responses were seen, four of six patients with stable disease remained on study for at least a year (16, 17, 13 and 12 months) before developing progressive disease. Three of these prolonged stable disease patients had non-small cell lung cancer. We conclude that intermittent dosing of R115777 is feasible and tolerable. The recommended phase II dose is 600 mg orally b.i.d. on alternate weeks.

Pharmacology of oxaliplatin in solid tumor patients with hepatic dysfunction: a preliminary report of the National Cancer Institute Organ Dysfunction Working Group

Oxaliplatin, which was recently approved by the US Food and Drug Administration for the treatment of advanced colorectal cancer, is often administered to patients with altered liver function caused by hepatic metastases. Because of the absence of data on the clearance of oxaliplatin in patients with liver dysfunction, and to develop dosing recommendations for the safe use of oxaliplatin in this clinical setting, the Organ Dysfunction Working Group of the National Cancer Institute performed a phase I and pharmacokinetic trial of this drug in patients displaying a wide range of liver function abnormalities. Sixty patients grouped into five classes of liver function were enrolled in this study, including a 12-patient control group with normal liver function, 15 patients with "mild," 16 patients with "moderate," and 16 with "severe" liver dysfunction, as well as one patient who had undergone liver transplantation. The patients had a median age of 62 years and a Eastern Cooperative Oncology Group performance status of 0. All patients had received prior systemic chemotherapy, and 70% had a diagnosis of a gastrointestinal malignancy. The control patients were treated with 130 mg/m(2) oxaliplatin intravenously every 21 days; the starting doses for patients with mild, moderate, or severe liver dysfunction or post-liver transplantation were 105, 80, or 60 mg/m(2), respectively. Cohorts of three or more patients were escalated from these starting doses to 130 mg/m(2) if dose-limiting toxicities were not observed, and pharmacokinetic evaluations were performed at each dose level for every category of liver dysfunction. We found that oxaliplatin was well tolerated at its recommended dose and schedule of 130 mg/m(2) every 21 days in patients with all levels of liver dysfunction, and that there was no apparent alteration in the clearance of either total or ultrafilterable platinum species from plasma, even in patients with severe hepatic functional abnormalities.

Pharmacogenomics in colorectal cancer

The goal in administering chemotherapeutics is to develop the ability to predict the outcome of therapy in terms of response and toxicity. Technology has been developed to allow tumor profiling with the measurement of protein expression and gene expression levels of markers and even genetic polymorphisms that may predict response to particular chemotherapeutics. The chemotherapeutics for which particular markers have been shown to predict outcome include the fluoropyrimidines and platinums. The next step is to develop clinical trials that will prospectively assess the benefits of profiling a patient's particular tumor, which should translate into an improvement in response and toxicity.

Pharmacogenetic aspects in treatment of colorectal cancer – an update

Pharmacogenomic analyses will become crucial to predict patients’ toxicity to treatment and will also help to predict the tumor response. Processes of drug metabolism, drug efflux, DNA-repair and characteristics of drug targets are critical checkpoints of drug efficacy. These crucial pathways for drug action have been part of pharmacogenomic studies evaluating the impact of genomic variants on transcription, translation, protein structure and substrate binding of the genes involved. Promising candidates have been identified with predictive value for response and toxicity to chemotherapy in colorectal cancers. These candidates need to be incorporated into large, prospective clinical trials to confirm their impact for response and survival to chemotherapy that has been reported in retrospective analyses. Confirmed predictive markers, together with additional yet to be identified pharmacogenomic key players, will provide the basis for tailoring chemotherapy in the future.

SU5416 plus interferon alpha in advanced renal cell carcinoma: a phase II California Cancer Consortium Study with biological and imaging correlates of angiogenesis inhibition

PURPOSE

Vascular endothelial growth factor (VEGF) is expressed in up to 70% of renal cell carcinomas (RCCs) and is a rational therapeutic target. SU5416 is a small molecule inhibitor of VEGF-mediated signaling through Flk-1, a transmembrane tyrosine kinase. IFN-alpha also possesses dose- and schedule-dependent antiangiogenic effects at doses lower than those used for RCC therapy. We hypothesized that SU5416 plus low dose IFN-alpha 2B (Intron-A) would result in a 1-year event-free survival (EFS), exceeding 20% in patients with metastatic RCC using the results of a randomized immunotherapy trial as historical control. Efficacy was correlated with serial plasma VEGF and plasminogen activator inhibitor-1 levels and with positron emission tomography scans.

EXPERIMENTAL DESIGN

Thirty patients were treated with SU5416 145 mg/m(2) i.v. twice weekly plus Intron-A 1 million units s.c. twice daily, cycled every 6 weeks.

RESULTS

Fifteen patients (50%) had stable disease (SD) at 12 weeks, including 1 minor response and 8 with progressive disease (27%). Median survival time was 10 months, and 1-year EFS was 6% (95% confidence interval, 1-35). The most common grade 3 or 4 toxicities included fatigue and lymphopenia, among others. There were 3 on-study deaths, 2 of which were infection-related. Significant declines in median plasma levels of VEGF pre- and posttherapy were observed. In 5 patients with paired FDG and O-15 positron emission tomography scans, tumor metabolism and perfusion were unchanged in 3 patients with SD, increased in 1 patient with progression, and decreased in 1 patient with SD.

CONCLUSIONS

Although SU5146 plus low-dose IFN exhibits biological activity in RCC as evidenced by significant declines in serial VEGF and plasminogen activator inhibitor-1 plasma levels, the 1-year EFS of 6% and adverse toxicity profile diminishes enthusiasm for additional studies with this combination in advanced RCC.

Tirapazamine plus carboplatin and paclitaxel in advanced malignant solid tumors: a california cancer consortium phase I and molecular correlative study

PURPOSE

Tumor hypoxia confers chemotherapy resistance. Tirapazamine is a cytotoxin that selectively targets hypoxic cells and has supra-additive toxicity with platinums and taxanes in preclinical studies. We conducted a Phase I study of tirapazamine, carboplatin, and paclitaxel and assessed potential plasma markers of hypoxia as surrogates for response.

EXPERIMENTAL DESIGN

Forty-two patients with advanced solid tumors were treated at four dose levels; parallel dose escalations were carried out in chemotherapy-naive and previously treated subjects. Pre and post-therapy plasma levels of the hypoxia-induced proteins plasminogen activator inhibitor-1 and vascular endothelial growth factor were measured.

RESULTS

Three of four chemotherapy-naïve patients developed dose-limiting toxicities at dose level 4 (grade 3 stomatitis/infection, grade 3 emesis, and grade 4 febrile neutropenia). Four of seven previously treated patients developed dose-limiting toxicities at dose level 3, including one death [grade 3 myalgia, grade 3 infection/grade 4 neutropenia, grade 3 infection/grade 4 neutropenia, and grade 5 infection (death)/grade 4 neutropenia]. Of 38 patients assessable for response, 3 had a complete response, 1 a partial response, 1 an unconfirmed partial response, and 23 had stable disease in at least one evaluation; 10 quickly progressed. One complete responder had normalization of vascular endothelial growth factor and plasminogen activator inhibitor-1 levels.

CONCLUSION

Dose levels 3 (carboplatin AUC of 6, 225 mg/m(2) paclitaxel, and 330 mg/m(2) tirapazamine) and 2 (carboplatin AUC 6, 225 mg/m(2) paclitaxel, and 260 mg/m(2) tirapazamine) are the maximum tolerated doses for chemotherapy naive and patients treated previously, respectively. Dose level 3 is the experimental arm of a Phase III Southwest Oncology Group trial (S0003) in advanced non-small cell lung cancer. Potential markers of tumor hypoxia may be useful correlates in studies of hypoxic cytotoxins and are being prospectively investigated in S0003.

Clinical update: proteasome inhibitors in solid tumors

The proteasome plays a critical role in regulating the cell cycle, neoplastic growth, and metastasis. Bortezomib (VELCADE; formerly PS-341, LDP-341, MLN341) is a novel dipeptide boronic acid that is the first proteasome inhibitor to have progressed to clinical trials. Preclinical research has shown that through the prevention of IkappaB degradation, bortezomib may block chemotherapy-induced NF-kappaB activation and augment the apoptotic response to chemotherapeutic agents. Bortezomib also appeared to increase the stabilization of p21 and p27, as well as transcription factor p53. In preclinical models of breast, lung, pancreatic, and ovarian tumor types, bortezomib inhibited tumor growth and demonstrated anti-angiogenic properties. Bortezomib exhibited the greatest activity when combined with standard chemotherapeutic agents, such as irinotecan, gemcitabine, and docetaxel, suggesting its potential additive/syngeristic role in overcoming resistance to conventional chemotherapy. Preliminary data from early clinical trials suggest that bortezomib can be given at pharmacologically active doses in combination with standard doses of chemotherapy with manageable toxicities. Responses have been seen and no evidence of additive toxicity has been exhibited in combination agent trials.

Targeted therapy and pharmacogenomic programs

The goal in administering chemotherapeutics is to develop the ability to predict the outcome of therapy in terms of response and toxicity. Technology has been developed to allow tumor profiling with measurement of protein expression, gene expression levels of markers, and even genetic polymorphisms, which may predict response to particular chemotherapeutics. The chemotherapeutics for which particular markers have been shown to predict outcome include the fluoropyrimidines and platinums. The next step is to develop clinical trials that will assess prospectively the benefits of profiling a patient's particular tumor, which should translate into an improvement in response and toxicity.

Thymidylate synthase gene polymorphism determines response and toxicity of 5-FU chemotherapy

Thymidylate synthase (TS) catalyses the conversion of deoxy-uridylate to deoxy-thymidylate and is essential for DNA synthesis. The human TS gene promoter is polymorphic, having either double or triple tandem repeats of a 28-bp sequence. Here we determined the significance of this polymorphism in humans and its prediction for clinical outcome of patients with metastatic colorectal cancer treated with 5-fluorouracil. The TS mRNA level was analyzed using RT-PCR. Individuals homozygous for the triple repeat variant (L/L) had 3.6 times higher TS mRNA levels compared to those homozygous for the double repeat variant (S/S) in tumor tissue (P = 0.004). We tested 50 patients with disseminated colorectal cancer who received 5-FU treatment to determine whether this TS polymorphism will predict clinical outcome. We found individuals with S/S genotype had a response rate of 50% (4/8) when compared to 9% (2/22) in those with L/L and 15% (3/20) in those with S/L genotype (P = 0.041). Patients with L/L had less severe side effects to 5-FU (P = 0.008). The data suggest that genotyping for the TS polymorphism may have the potential to identify patients more likely to respond to 5-FU based chemotherapy.

A Xeroderma pigmentosum group D gene polymorphism predicts clinical outcome to platinum-based chemotherapy in patients with advanced colorectal cancer

The Xeroderma pigmentosum group D (XPD) protein is an essential participant in nucleotide excision repair and basal transcription. There is evidence that three common polymorphisms of the XPD gene (C156A, Asp312Asn, and Lys751Gln) may be associated with differential DNA repair activity. Because increased DNA repair plays an important role in chemoresistance to platinum-based compounds, we assessed the aforementioned polymorphisms in 73 patients with metastatic colorectal cancer and determined their outcome to 5-fluorouracil/oxaliplatin. Among those tested for the Lys751Gln polymorphism, 24% (5 of 21) patients with the Lys/Lys genotype responded, versus 10% (4 of 39) and 10% (1 of 10) of those with the Lys/Gln and Gln/Gln genotypes (P = 0.015). The median survival for those with the Lys/Lys genotype was 17.4 (95% CI 7.9, 26.5) versus 12.8 (95% CI 8.5, 25.9) and 3.3 (95% CI 1.4, 6.5) months for patients with the Lys/Gln and Gln/Gln respectively (P = 0.002). The polymorphisms C156A and Asp312Asn of the XPD gene were not associated with response to 5-fluorouracil/oxaliplatin nor with survival. However, a linkage was observed between the Lys751 allele and the C156 allele (P = 0.028), and between the Lys751Lys genotype and the Asp312Asp genotype (P < 0.001). We conclude that XPD Lys751Gln polymorphism may be an important marker in the prediction of clinical outcome to platinum-based chemotherapy.

ERCC1 and thymidylate synthase mRNA levels predict survival for colorectal cancer patients receiving combination oxaliplatin and fluorouracil chemotherapy

PURPOSE

To test the hypotheses of whether the relative mRNA expression of the thymidylate synthase (TS) gene and the excision cross-complementing (ERCC1) gene are associated with response to and survival of fluorouracil (5-FU)/oxaliplatin chemotherapy in metastatic colorectal cancer.

PATIENTS AND METHODS

Patients had progressive stage IV disease after unsuccessful 5-FU and irinotecan chemotherapy. All patients were evaluated for eligibility for a compassionate 5-FU/oxaliplatin protocol. cDNA was derived from paraffin-embedded tumor specimens to determine TS and ERCC1 mRNA expression relative to the internal reference gene beta-actin using fluorescence-based, real-time reverse transcriptase polymerase chain reaction.

RESULTS

The median TS gene expression level from 50 metastasized tumors was 3.4 x 10(-3) (minimum expression, 0.18 x 10(-3);maximum expression, 11.5 x 10(-3)), and the median ERCC1 gene expression level was 2.53 x 10(-3) (minimum, 0.0; maximum, 14.61 x 10(-3)). The gene expression cutoff values for chemotherapy nonresponse were 7.5 x 10(-3) for TS and 4.9 x 10(-3) for ERCC1. The median survival time for patients with TS <or= 7.5 x 10(-3) (43 of 50 patients) was 10.2 months, compared with 1.5 months for patients with TS greater than 7.5 x 10(-3) (P < .001). Patients with ERCC1 expression <or= 4.9 x 10(-3) (40 of 50 patients) had a median survival time of 10.2 months, compared with 1.9 months for patients with ERCC1 expression greater than 4.9 x 10(-3) (P < .001). A TS of 7.5 x 10(-3) segregated significantly into response, stable disease, and progression (P = .02), whereas the association between ERCC1 and response did not reach statistical significance (P = .29).

CONCLUSION

These data suggest that intratumoral ERCC1 mRNA and TS mRNA expression levels are independent predictive markers of survival for 5-FU and oxaliplatin combination chemotherapy in 5-FU-resistant metastatic colorectal cancer. Precise definition of the best TS cut point will require further analysis in a large, prospective study.

Activity of high-dose toremifene plus cisplatin in platinum-treated non-small-cell lung cancer: a phase II California Cancer Consortium Trial

PURPOSE

Although cisplatin is an important agent in non-small-cell lung cancer (NSCLC), de novo resistance is common and acquired resistance emerges rapidly during therapy. Proposed mediators of platinum resistance include the protein kinase C (PKC) signal transduction pathway and associated c-FOS overexpression. While estrogen administration has been reported to upregulate PKC and c-FOS expression, the triphenylethylenes tamoxifen and toremifene potentiate platinum cytotoxicity by inhibition of PKC. Downregulation of c-FOS expression has been reported to result from PKC inhibition. In view of these findings, we hypothesized that toremifene would reverse platinum resistance and that this interaction would be influenced by tumor estrogen receptor (ER) status.

MATERIALS AND METHODS

A phase II trial of high-dose toremifene (600 mg orally daily on days 1-7) plus cisplatin (50 mg/m2 intravenously on days 4 and 11) every 28 days in NSCLC patients was conducted. A group of 30 patients with metastatic NSCLC who had been previously treated with platinum-based therapy were enrolled.

RESULTS

All of the 30 patients were assessable for toxicity and 28 for tumor response. Therapy was well tolerated with minimal hematologic and non-hematologic toxicity. Common toxicity criteria grade 3 hematologic toxicity was seen in only three patients. Five patients achieved a partial response for an overall response rate of 18% (95% CI 6-37). Median overall survival was 8.1 months (95% CI 5.4-17). To assess PKC, ER, and c-Fos expression by immunohistochemistry, 12 informative pretreatment patient tumor specimens were obtained. Four patient tumor specimens were positive for one or both PKC isoforms (alpha and epsilon) while c-Fos was overexpressed in three. None of the responding patient tumors exhibited c-FOS or PKC-epsilon overexpression. ER expression was found to be infrequent (8%), contrasting with previous reports in this tumor type.

CONCLUSION

While this phase II study indicates that high-dose toremifene plus cisplatin is feasible, active, and well tolerated in NSCLC patients previously treated with platinum compounds, the mechanism of action remains unclear. Further study of this regimen is warranted.

A polymorphism of the XRCC1 gene predicts for response to platinum based treatment in advanced colorectal cancer

Recently, it has been demonstrated that the Arg399Gln substitution in the XRCC1 gene is associated with increased levels of markers of DNA damage. Deficiency in DNA repair pathways has been shown to confer to resistance to several drugs, including platinum compounds. Here we have studied whether this polymorphism of the XRCCI gene will predict response and survival of patients with metastatic colorectal cancer treated with oxaliplatin and 5-FU. Sixty-one patients received a combination of 130 mg/m2 oxaliplatin and continuous infusion 5-FU. The XRCC1 polymorphism was evaluated using a RFLP method. We found 73% (8/11) of responders had an Arg/Arg genotype and three were heterozygous, but 66% (33/50) of non-responders showed a Gln/Gln or Gln/Arg genotype (p=0.038). Patients carrying at least one Gln mutant allele were at a 5.2 (95%CI: 1.21,22.07) fold increased risk to fail the 5-FU/oxaliplatin chemotherapy. The data suggest that the polymorphism in exon 10 of the XRCC1 gene may be associated with resistance to oxaliplatin/5-FU chemotherapy in advanced colorectal cancer.

Phase II trial of outpatient schedule of paclitaxel in patients with previously untreated metastatic, measurable adenocarcinoma of the stomach

BACKGROUND

Chemotherapy represents the standard treatment for patients with metastatic stomach cancer. Conflicting results have been published regarding the activity of paclitaxel in this setting. Therefore, we developed a phase II study to evaluate an outpatient 3 h infusion of paclitaxel.

METHODS

Patients with chemonaive metastatic stomach cancer received paclitaxel 210 mg/m(2) every 3 weeks. Patients with esophageal cancer were not eligible.

RESULTS

Twenty-one patients were enrolled. The median age was 55.5 years (range 37-81 years). Two partial responses were observed among the 18 patients evaluable for response and toxicity (response rate 11%, 95% CI: 2-33%). The median time to progression was 10.5 weeks and median survival 23 weeks. There was only one episode of grade IV neutropenia and no episodes of grade 3-4 non-hematological toxicity were observed.

CONCLUSION

Paclitaxel exhibited minimal activity in this patient population.

Sensitive and reproducible quantitation of mucosal HIV-1 RNA and DNA viral burden in patients with detectable and undetectable plasma viral HIV-1 RNA using endoscopic biopsies

Mucosal tissue is the main portal of entry for HIV-1 infection and, in macaques, has been demonstrated to be a significant compartment for viral replication and CD4+ T lymphocyte depletion. Quantitating tissue viral burden in addition to plasma viral load provides insights into HIV-1 pathogenesis and an additional means to gauge antiretroviral response. The aim of this study was to develop reliable, reproducible, and sensitive assays to quantitate tissue viral burden of HIV-1 RNA and DNA using 1-3 endoscopically acquired, rectosigmoid biopsies. Total DNA and RNA were simultaneously extracted following homogenization from the same tissue samples. Quantitative polymerase chain reaction (PCR) assay in the HIV-1 LTR region was used to detect viral DNA and RT-PCR for viral RNA. It was determined that HIV-1 RNA and DNA can be reproducibly quantified from a single rectosigmoid biopsy with minimal intra-assay or intra-patient variability. These results reflect high recovery of extracted nucleic acids with calculated results accurately reflecting in vivo levels. The techniques outlined differ from currently available approaches by incorporating control standards to identify loss or degradation of RNA and DNA from acquisition through the in vitro assay and permit extraction with high yields of RNA and DNA from the same tissue sample.

Phase I trial of 96-hour continuous infusion of dexrazoxane in patients with advanced malignancies

Dexrazoxane is a bidentate chelator of divalent cations. Pretreatment with short infusions of dexrazoxane prior to bolus doxorubicin has been shown to lessen the incidence and severity of anthracycline-associated cardiac toxicity. However, because of rapid, diffusion-mediated cellular uptake and the short plasma half-life of dexrazoxane, combined with prolonged cellular retention of doxorubicin, dexrazoxane may be more effective when administered as a continuous infusion. Thus, a Phase I pharmacokinetic trial of a 96-h infusion of dexrazoxane was performed. Dexrazoxane doses were escalated in cohorts of 3 to 6 patients per dose level. All patients received granulocyte-colony stimulating factor at a dose of 5 microg/kg/day starting 24 h after completion of the dexrazoxane infusion. Plasma samples were collected and analyzed for dexrazoxane by high-performance liquid chromatography. Urine collections were performed at baseline and during the infusion to determine the renal clearance of dexrazoxane and the excretion rate of divalent cations. Twenty-two patients were enrolled at doses ranging from 125 to 250 mg/m(2)/day. Grade 3 and 4 toxicities included grade 4 thrombocytopenia in 2 patients treated at 250 mg/m(2)/day, grade 3 thrombocytopenia and grade 4 nausea and vomiting in 1 patient treated at 221 mg/m(2)/day, grade 4 diarrhea and grade 3 nausea and vomiting in 1 patient treated at 221 mg/m(2)/day, and grade 3 hypertension in 1 patient treated at 166.25 mg/m(2)/day. Steady-state dexrazoxane levels ranged from 496 microg/l (2.2 microM) to 1639 microg/l (7.4 microM). Dexrazoxane plasma CL(ss) and elimination t(1/2) were 7.2 +/- 1.6 l/h/m(2) and 2.0 +/- 0.8 h, respectively. The mean percentage of administered dexrazoxane recovered in the urine at steady state was 30% (range, 10-66%). Urinary iron and zinc excretion during the dexrazoxane infusion increased in 12 of 18 and 19 of 19 patients by a median of 3.7- and 2.4-fold, respectively. These results suggest that dexrazoxane as a 96-h infusion can be safely administered with granulocyte-colony stimulating factor at doses that achieve plasma levels that have been demonstrated previously to inhibit topoisomerase II activity and to induce apoptosis in vitro. Additional studies will be required to determine whether the combination of continuous infusions of dexrazoxane and doxorubicin would provide enhanced cardioprotection compared with the currently recommended bolus or short infusion schedules.

Determinants of prognosis and response to therapy in colorectal cancer

Identification of the molecular determinants of 5-fluorouracil (5-FU) and irinotecan (CPT-11) efficacy and toxicity is critically important for the development of more efficient and less toxic treatment strategies for patients with colon cancer. We have identified molecular predictors of response to chemotherapy with 5-FU and survival in patients with advanced colorectal cancer. Low gene expression levels of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) are associated with response and survival. Preliminary data suggest that gene expression levels of topoisomerase I, p21, bcl-2, and ICE may be predictive of response to therapy with CPT-11. Increased toxicity seen in patients treated with CPT-11 may be explained by polymorphism in the UGT1A1 gene, which is responsible for glucuronidation of the active metabolite of CPT-11.

[Molecular markers as basis for chemotherapy?]

Although a majority of cancer patients show no response or minimal response to any given chemotherapy, all patients are nevertheless placed on standard therapy regimens because there has been no way to identify beforehand those patients who are destined not to respond. Determining the biochemical factors relevant to drug response in each patient's tumor cells prior to treatment should allow optimal therapy to be selected for each patient on a rational basis. In this paper, we summarize studies aimed at determining whether analysis of the quantitative expression levels of genes or proteins involved in cancer drug activity in clinical specimens of tumor tissue could predict the effect of the drug on a tumor. This hypothesis has been tested mostly in 5-fluorouracil (5-FU)-based regimens in colorectal cancer. In the case of 5-FU, the quantitative expression levels of thymidylate synthase, thymidine phosphorylase, and dihydropyrimidine dehydrogenase were found to be associated with tumor response. Using all three of these markers together resulted in very effective identification of responding patients. The salient results of these studies were that, using the PCR enhanced by newly developed methodology, gene expressions can be identified and measured in pretreatment biopsies that are quantitatively associated with either response or non-response to drugs that are used in treating colorectal cancer.

dUTP nucleotidohydrolase isoform expression in normal and neoplastic tissues: association with survival and response to 5-fluorouracil in colorectal cancer

Aberrant dUTP metabolism plays a significant role in the underlying molecular mechanisms of cell killing mediated by inhibitors of thymidylate biosynthesis. dUTP nucleotidohydrolase (dUTPase) is the key regulator of dUTP pools, and significant evidence exists suggesting that the expression of this enzyme may be an important determinant of cytotoxicity mediated by inhibitors of thymidylate synthase (TS). In this study, we have determined the expression patterns of dUTPase in normal and neoplastic tissues and examined the association between dUTPase expression and response to 5-fluorouracil (5-FU)-based chemotherapy and overall survival in colorectal cancer. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections using a monoclonal antibody (MAb), DUT415, that cross-reacts with both nuclear and mitochondrial isoforms of human dUTPase. Nuclear and cytoplasmic staining was observed in both normal and neoplastic tissues. In normal tissues, nuclear dUTPase staining was observed exclusively in replicating cell types. This observation is in agreement with cell culture studies where expression of the nuclear isoform (DUT-N) is proliferation dependent In contrast, cytoplasmic expression of dUTPase does not correlate with proliferation status and was observed in tissues rich in mitochondria. Consistent with this observation, cell culture studies reveal that the mitochondrial isoform (DUT-M) is expressed constitutively, independent of cell cycle status. These data suggest that in normal tissues, nuclear staining with the DUT415 antibody represents the DUT-N isoform, whereas cytoplasmic staining represents the DUT-M isoform. In colon cancer tumor specimens, expression of dUTPase was shown to be highly variable in both amount and intracellular localization. Patterns of dUTPase protein expression observed included exclusive nuclear, exclusive cytoplasmic, and combined nuclear and cytoplasmic staining. Thus, immunohistochemical detection of dUTPase in colon cancers provides distinct intracellular phenotypes of expression that may be of significant prognostic value. To examine the association between dUTPase expression and response to 5-FU-based chemotherapy and overall survival, we initiated a retrospective study including tumor specimens from 20 patients who had received protracted infusion of 5-FU and leucovorin for treatment of metastatic colon cancer. Positive nuclear staining was found in 8 patients, whereas 12 lacked nuclear expression. Of the patients lacking nuclear dUTPase expression, 6 responded to 5-FU-based chemotherapy, 4 had stable disease, and 2 had progressive disease. Of the patients presenting positive nuclear dUTPase expression, 0 responded to chemotherapy, 1 had stable disease, and 7 had progressive disease (P = 0.005). The median survival for patients with tumors lacking nuclear staining was 8.5 months and 6.9 months for patients with tumors demonstrating positive nuclear dUTPase expression (P = 0.09). Time to progression was significantly longer for patients with tumors lacking nuclear staining (P = 0.017). Variable cytoplasmic dUTPase expression was observed in these tumors; however, there was no apparent association with clinical response or survival in this limited study. Nuclear dUTPase staining within these tumors was also associated with TS gene expression (P = 0.06). This study demonstrates that low intratumoral levels of nuclear dUTPase protein expression is associated with response to 5-FU-based chemotherapy, greater time to progression, and greater overall survival in colorectal cancer. Conversely, high levels of nuclear dUTPase protein expression predict for tumor resistance to chemotherapy, shorter time to progression, and shorter overall survival. This report represents the first clinical study implicating dUTPase overexpression as a mechanism of resistance to TS inhibitor-based chemotherapy.

Colorectal tumors responding to 5-fluorouracil have low gene expression levels of dihydropyrimidine dehydrogenase, thymidylate synthase, and thymidine phosphorylase

We had previously shown that high gene expressions (mRNA levels) of thymidylate synthase (TS; Leichman et al., J. Clin. Oncol., 15: 3223-3229, 1997) and thymidine phosphorylase (TP; Metzger et al., Clin. Cancer Res., 4: 2371-2376, 1998) in pretreatment tumor biopsies could identify tumors that would be nonresponsive to 5-fluorouracil (5-FU)-based therapy. In this study, we investigated the association between intratumoral gene expression of the pyrimidine catabolism enzyme dihydropyrimidine dehydrogenase (DPD) and the response of colorectal tumors to the same 5-FU-based protocol. DPD expressions were measured by quantitative reverse transcription-PCR in 33 pretreatment biopsies of colorectal tumors from patients who went on to receive treatment with 5-FU and leucovorin (LV). The range of DPD gene expression in those tumors that were nonresponsive to 5-FU was much broader than that of the responding tumors. None of the tumors with basal-level DPD expressions above a DPD:beta-actin ratio of 2.5 x 10(-3) (14 of 33) were responders to 5-FU/LV therapy, whereas those tumors with DPD gene expressions below DPD: beta-actin ratio of 2.5 x 10(-3) had a response rate of 50%. There was no correlation among DPD, TS, and TP expression values in this set of colorectal tumors, which indicated that these gene expressions are independent variables. All of the tumors that responded to 5-FU therapy (11 of 33) had expression values of all three of the genes, TS, TP, and DPD, below their respective nonresponse cutoff values, whereas, in each of the nonresponding tumors, at least one of these gene expressions was high. The patients with low expression of all three of the genes had significantly longer survival than patients with a high value of any one of the gene expressions. The results of this study show that intratumoral gene expression level of DPD is associated with tumor response to 5-FU and that the use of more than one independent determinant of response permits the identification of a high percentage of responding patients.

High basal level gene expression of thymidine phosphorylase (platelet-derived endothelial cell growth factor) in colorectal tumors is associated with nonresponse to 5-fluorouracil

The gene expression levels of the nucleoside cleavage enzyme/angiogenic factor thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, were measured by quantitative reverse transcription-PCR in 38 pretreatment biopsies of colorectal tumors from patients who were subsequently treated with 5-fluorouracil (5-FUra) and leucovorin (LV). The range of TP gene expression (relative mRNA levels) in those tumors nonresponsive to 5-FUra was much broader than that of the responding tumors. In contrast to in vitro studies that had shown that an increased intracellular level of TP potentiates the activity of 5-FUra by converting it to the more cytotoxic nucleoside form 5-fluoro-2'deoxyuridine, tumors with the highest basal TP expressions were nonresponders to 5-FUra/LV therapy. The mean TP mRNA level in the nonresponding tumors was 2.6-fold higher than that of the responding patients. We had shown previously that high expression of thymidylate synthase (TS), the target enzyme of 5-FUra, was also a predictor of nonresponse to 5-FUra (L. Leichman et al, J. Clin. Oncol., 15: 3223-3229, 1997). TP and TS expressions were found to be independent variables in these tumors, so that low expression levels of both TS and TP in tumors predicted a very high response rate (11 of 14) to 5-FUra/LV as well as a significantly longer survival, whereas none (0 of 24) of the patients with high expression of either TP or TS were responders.