Vascular reactions to in vivo electroporation: characterization and consequences for drug and gene delivery.

In vivo electroporation (EP) is gaining momentum for drug and gene delivery. In particular, DNA transfer by EP to muscle tissue can lead to highly efficient long-term gene expression. We characterized a vascular effect of in vivo EP and its consequences for drug and gene delivery. Pulses of 10-20,000 micros and 0.1-1.6 kV/cm were applied over hind- and forelimb of mice and perfusion was examined by dye injection. The role of a sympathetically mediated vasoconstrictory reflex was investigated by pretreatment with reserpine. Expression of a transferred gene (luciferase), permeabilization (determined using (51)Cr-EDTA), membrane resealing and effects on perfusion were compared to assess the significance of the vascular effects. Above the permeabilization threshold, a sympathetically mediated Raynaud-like phenomenon with perfusion delays of 1-2 min was observed. Resolution of this phase followed kinetics of membrane resealing. Above a second threshold, irreversible permeabilization led to long perfusion delays. These vascular reactions (1) affect kinetics of drug delivery, (2) predict efficient DNA transfer, which is optimal during short perfusion delays, and (3) might explain electrocardiographic ST segment depressions after defibrillation as being caused by vascular effects of EP of cardiac muscle.

Use of peptide antibodies to probe for the mitoxantrone resistance-associated protein MXR/BCRP/ABCP/ABCG2.

Recent studies have characterized the ABC half-transporter associated with mitoxantrone resistance in human cancer cell lines. Encoded by the ABCG2 gene, overexpression confers resistance to camptothecins, as well as to mitoxantrone. We developed four polyclonal antibodies against peptides corresponding to four different epitopes on the mitoxantrone resistance-associated protein, ABCG2. Three epitopes localized on the cytoplasmic region of ABCG2 gave rise to high-affinity antibodies, which were demonstrated to be specific for ABCG2. Western blot analysis of cells with high levels of ABCG2 showed a single major band of the expected 72-kDa molecular size of ABCG2 under denaturing conditions. Immunoblot analysis performed under non-reducing conditions and after treatment with cross-linking reagents demonstrated a molecular weight shift from 72 kDa to several bands of 180 kDa and higher molecular weight, suggesting detection of dimerization products of ABCG2. Evidence of N-linked glycosylation was also obtained using tunicamycin and N-glycosidase F. Finally, both by light, fluorescence and electron microscopic immunohistochemical staining, we demonstrate cytoplasmic and predominantly plasma membrane localization of ABCG2 in cell lines with high levels of expression. Plasma membrane staining was observed on the surface of the chorionic villi in placenta. These results support the hypothesis that ABCG2 is an ABC half-transporter that forms dimers in the plasma membrane, functioning as an ATP-dependent outward pump for substrate transport.

Randomized comparative study of tegafur/uracil and oral leucovorin versus parenteral fluorouracil and leucovorin in patients with previously untreated metastatic colorectal cancer.

PURPOSE: This phase III study compared the time to progression (TTP) of an oral regimen of dihydropyrimidine dehydrogenase inhibitory fluoropyrimidine composed of a fixed combination of tegafur and uracil in a 1:4 molar ratio (UFT) and leucovorin (LV) to intravenous (IV) fluorouracil (5-FU) and LV in previously untreated metastatic colorectal carcinoma (CRC) patients. Secondary end points were survival, tumor response, safety, and quality of life. PATIENTS AND METHODS: Between May 1996 and July 1997, 380 patients were randomized to receive either UFT (300 mg/m(2)/d) and LV (90 mg/d), administered for 28 days every 35 days, or 5-FU (425 mg/m(2)/d) and LV (20 mg/m(2)/d), given IV for 5 days every 35 days. RESULTS: No statistically significant difference in TTP was observed between treatments. With 320 events assessed, the median TTP was 3.4 months (95% Confidence interval [CI], 2.6 to 3.8) on UFT/LV and 3.3 months (95% CI, 2.5 to 3.7) on 5-FU/LV (P =.591, stratified log-rank test). There were no statistically significant differences in survival, tumor response, duration of response, and time to response. Substantial safety benefits were observed in patients treated with UFT/LV. They experienced significantly less stomatitis/mucositis (P <.001) and myelosuppression, resulting in fewer episodes of febrile neutropenia (P <.001) and less documented infection (P =.04). Concomitant medication usage was significantly greater on 5-FU/LV (P =.010). With respect to quality of life, after correcting for baseline imbalances, there were no significant differences between treatments for any scale, except diarrhea. CONCLUSION: The oral UFT/LV regimen failed to achieve improved TTP; however, the study confirms significant safety improvements compared with bolus IV 5-FU/LV for the first-line treatment of metastatic CRC.

Influence of chemosensitizers on resistance mechanisms in daunorubicin-resistant Ehrlich ascites tumour cells.

AIM: To determine whether treatment with chemosensitizers influences the development of the drug-resistant phenotype. METHODS: Three sublines were developed from the sensitive Ehrlich ascites tumour cell line (EHR2) and six sublines from the EHR2/DNR cell line positive for P-glycoprotein (PGP) by treatment with daunorubicin (DNR), a combination of DNR and verapamil (VER), or a combination of DNR and cyclosporin A (CsA). A clonogenic assay was used to determine resistance, the expression of PGP, the multidrug resistance associated protein ( Mrp1) and topoisomerase IIalpha and beta were measured by Western blotting, and reverse transcriptase-polymerase chain reaction was used for determination of mdr1a and b, and Mrp1 mRNA. RESULTS: Compared with the EHR2 cell line, the amounts of mdr1a mRNA increased significantly in all sublines except EHR2/DNR, whereas mdr1b mRNA levels were unchanged. Compared with the EHR2 subline selected in DNR alone, the levels of mdr1a mRNA and PGP were significantly lower in the EHR2 sublines selected in the presence of chemosensitizer. Furthermore, mdr1a mRNA and PGP were unchanged in all cotreated sublines selected from the PGP-positive EHR2/DNR cell line. The mRNA and protein levels of Mrp1 did not change significantly in any of the cell lines. Only one DNR plus VER-selected subline showed a decrease in topoisomerase IIalpha (one-third as compared with EHR2). All DNR plus CsA-selected sublines showed significantly less resistance than the corresponding DNR- and DNR plus VER-selected sublines. The effect of VER and CsA on cytotoxicity was retained in all cell lines treated with chemosensitizer. CONCLUSIONS: Selection in chemosensitizer resulted in a decrease in the expression of mdr1a and PGP. These chemosensitizers do not seem to influence Mrp1 expression or topoisomerase II. Selection in CsA may retard the development of resistance.

Double-blind, placebo-controlled, randomized study of chlorhexidine prophylaxis for 5-fluorouracil-based chemotherapy-induced oral mucositis with nonblinded randomized comparison to oral cooling (cryotherapy) in gastrointestinal malignancies.

BACKGROUND: The purpose was to evaluate prevention of oral mucositis (OM) using chlorhexidine compared with placebo and with oral cooling (cryotherapy) during fluorouracil (5-FU)-based chemotherapy in gastrointestinal (GI) cancer. METHODS: Patients with previously untreated GI cancer receiving bolus 5-FU/leucovorin chemotherapy were randomized to chlorhexidine mouthrinse 3 times a day for 3 weeks (Arm A), double-blind placebo (normal saline) with the same dose and frequency (Arm B), or cryotherapy with crushed ice 45 minutes during chemotherapy (Arm C). Patients self-reported on severity (CTC-grading) and duration of OM. RESULTS: Among 225 patients randomized, 206 answered the questionnaire (70, 64, and 63 patients in Arms A, B, and C, respectively) and were well balanced with respect to diagnoses, stage, age, sex, smoking habits, and performance status. Mucositis grade 3-4 occurred more frequently in Arm B (33%) than in A (13%, P< .01) and C (11%, P< .005). Duration was significantly longer in B than in both A (P= .035) and C (P= .003). CONCLUSIONS: The frequency and duration of OM are significantly improved by prophylactic chlorhexidine and by cryotherapy. The latter is easy and inexpensive but has limited use, as it is drug- and schedule-dependent. The current study is the first double-blind randomized evaluation of prophylactic chlorhexidine in a large adult patient population with solid tumors receiving highly OM-inducing chemotherapy. A role for chlorhexidine in the prevention of OM is suggested, which should be evaluated further.

New insight into epirubicin cardiac toxicity: competing risks analysis of 1097 breast cancer patients.

BACKGROUND: Current recommendations that cancer patients receive a maximum cumulative dose of 900 mg/m(2) epirubicin are based on the risk of epirubicin-mediated cardiotoxicity and do not take into account the competing risk of death from cancer. Here, we identify risk factors for cardiotoxicity and overall mortality and determine the cumulative dose of epirubicin that yields a 5% risk for cardiotoxicity for cancer patients from different risk backgrounds. METHODS: Data were collected from 1097 consecutive anthracycline-naive patients treated for metastatic breast cancer with epirubicin. Patients who developed congestive heart failure classified as New York Heart Association class 2 or higher were recorded as having cardiotoxicity. Independent Cox multiple regression analyses for cardiotoxicity and for overall mortality were followed by competing risks analysis, with cardiotoxicity as the primary event and death from all other causes as the competing event. All statistical tests were two-sided. RESULTS: A total of 11.4% of patients developed cardiotoxicity. Risk factors for cardiotoxicity included increased cumulative dose of epirubicin (hazard ratio per every 100 mg/m(2) administered = 1.40, 95% confidence interval = 1.21 to 1.61), patient age, predisposition to cardiac disease, history of mediastinal irradiation, or antihormonal treatment for metastatic disease. Risk factors for death from all other causes (including breast cancer) included lesser dosages of epirubicin, increased tumor burden, prior use of adjuvant chemotherapy, and patient age. The cumulative dosage of epirubicin that carries a 5% risk of cardiotoxicity was lower than previously assumed and was dependent on risks of both cardiotoxicity and overall mortality. CONCLUSION: Maximum cumulative dosages of epirubicin are presented that confer a 5% risk of cardiotoxicity for patients with different sets of risk factors.

Predictors of central nervous system metastasis in patients with metastatic breast cancer. A competing risk analysis of 579 patients treated with epirubicin-based chemotherapy.

In order to identify factors predictive of central nervous system (CNS) metastasis, we reviewed the histories of 579 patients treated with epirubicin-based chemotherapy for metastatic breast cancer. Statistical analysis included Kaplan-Meier survival plots, Cox's regression analysis and competing risk analysis using the cumulative incidence. Median follow-up-time was 137 months (range 0-183+). In this period, one hundred and twenty-four patients (21.4%) developed CNS metastasis. Lung, liver, and lymph node metastases and oestrogen receptor negative or unknown tumor were predictive as well. However, increased pretreatment lactate dehydrogenase (LDH) concentration in serum above the upper normal limits was the strongest single risk factor and should therefore be measured. The risk of CNS metastasis differed considerably among risk groups. Patients without risk factors had a cumulative incidence on 9%, compared to a cumulative incidence of 42%, when the serum LDH concentration was elevated to more than twice the upper normal limits.

Pumping of drugs by P-glycoprotein: a two-step process?

The apparent inhibition constant, Kapp, for the blockade of P-glycoprotein (P-gp) by four drugs, verapamil, cyclosporin A, XR9576 (tariquidar), and vinblastine, was measured by studying their ability to inhibit daunorubicin and calcein-AM efflux from four strains of Ehrlich cells with different levels of drug resistance and P-gp content. For daunorubicin as a transport substrate, Kapp was independent of [P-gp] for verapamil but increased strictly linearly with [P-gp] for vinblastine, cyclosporin A, and XR9576. A theoretical analysis of the kinetics of drug pumping and its reversal shows that Kapp for inhibition should increase linearly with the amount of pumps present in the membrane for a reverser that inhibits pumping from the cytoplasmic face. In contrast, if the reverser acts by blocking transport from the outer face, i.e., preemptively, Kapp should be independent of the number of pumps present. The experimental data suggest that verapamil blocks pumping at the extracellular face of the membrane, whereas the other three blockers act on pumping from the cytoplasmic phase. The maximum degree of inhibition was the same for all four blockers; thus, they do not act in parallel but rather, in serial, i.e., a drug that is pumped from the cytoplasmic phase has to pass the preemptive route upon leaving the cell. Our results are consistent with the Sauna-Ambudkar two-step model for pumping by P-gp. We suggest that the vinblastine/cyclosporin A/XR9576-binding site accepts daunorubicin at the cytoplasmic face and transfers it to the verapamil-binding site, from where daunorubicin is emptied at the extracellular surface.

Angiotensin converting enzyme inhibitors for cancer treatment?

Angiotensin converting enzyme inhibitors (ACEi) prescribed for cardiovascular and renal disease since 1980 are widely atoxic and several experimental studies and one epidemiological study have demonstrated an effect of ACEi on cancer. ACEi has the effect of modifying gene expression; inhibiting proliferation and invasion of cancer cells; reducing endothelial cell migration and angiogenesis in vitro, whereas tumour growth and metastasis were inhibited in vivo. Several mechanisms of action are possible but inhibition of matrix metalloprotease activity, reduced expression of vascular endothelial growth factor and interference with the renin-angiotensin system were demonstrated by the experimental studies. In this paper we review the laboratory investigations and epidemiological studies on the anti-cancer actions of ACEi and present a summary of the evidence regarding the potential use of ACEi in cancer treatment.

Extracellular matrix building marked by the N-terminal propeptide of procollagen type I reflect aggressiveness of recurrent breast cancer.

The purpose of our study was to examine the association between extracellular matrix homeostasis and aggressive breast cancer as reflected by the synthesis of type I collagen marked by circulating concentration of the aminoterminal propeptide of type I procollagen (PINP). Pre-therapeutic serum PINP concentrations were measured in 154 healthy women and 100 patients referred with their first metastatic manifestation of breast cancer and correlated to the metastatic pattern, response to therapy, time to progression and survival with a minimal follow-up of 5 years. Fifty-four percent of the patients had serum PINP concentrations greater than the 95th percentile of the healthy controls and 38% were high PINP level patients with values clearly outside normal range (>125 ng/ml). Patients with high PINP levels were more sick (p = 0.002), had a higher tumor burden (p = 0.013) and revealed a lower responsiveness to anthracycline-based therapy (p = 0.0002) as well as an accelerated time to disease progression (p = 0.00001) and death (p = 0.0006). Median survival in the high serum PINP level group was less than half of that in the group with low PINP level (14.5 vs. 32 months). The lowest PINP levels were seen when the cancer was restricted to the lymph node and skin and increasing PINP levels were found if the cancer had spread to the lungs, the bones, the bone marrow and the liver. High PINP level at recurrence and lack of estrogen receptors (ER) independently reflected aggressive tumor behavior after recurrence with an equal great impact on time to progression and survival. Patients with a high PINP level and primarily ER-negative tumors survived a median of only 6 months with no one alive after 22 months. By contrast patients with a low PINP level and ER-positive tumors had a median survival of 37 months and 23% were still alive after 5 years. Aggressive breast cancer induces a strong fibroproliferative response with synthesis of type I collagen. Serum PINP levels may be a diagnostic and prognostic tool that indicate breast cancer activity, aggressiveness, expansion and metastasis and a predictor of outcome after anthracycline-based chemotherapy.

Edrecolomab alone or in combination with fluorouracil and folinic acid in the adjuvant treatment of stage III colon cancer: a randomised study.

BACKGROUND: Edrecolomab is a murine monoclonal antibody to the cell-surface glycoprotein 17-1A, which is expressed on epithelial tissues and on various carcinomas. Preliminary data suggested that it might be of use in the adjuvant treatment of patients with resected stage III colon cancer. We did a randomised trial in 27 countries to determine the effect of adding edrecolomab to the combination of fluorouracil and folinic acid in these patients. METHODS: After surgery, 2761 patients were randomly assigned edrecolomab plus fluorouracil-folinic acid (combination therapy [n=912]); fluorouracil-folinic acid alone (chemotherapy [n=927]); or edrecolomab alone (edrecolomab monotherapy [n=922]). Patients were assessed for survival and disease recurrence after surgery. The primary endpoint tested the hypothesis that combination therapy improved overall survival relative to chemotherapy. The key secondary endpoint was to test whether edrecolomab monotherapy was non-inferior to chemotherapy in terms of disease-free survival. Analysis was by intention to treat. FINDINGS: Median follow-up time was 26 months (IQR 20-36). 3-year overall survival on combination therapy was no different from that on chemotherapy (74.7% vs 76.1%, hazard ratio 0.94 [95% CI 0.76-1.15], p=0.53). Disease-free survival was significantly lower on edrecolomab monotherapy than on chemotherapy (53.0% vs 65.5%, 0.62 [0.53-0.73], p<0.0001). Hypersensitivity reactions occurred in 452 (25%) patients receiving edrecolomab, causing treatment discontinuation in 71 (4%). The addition of edrecolomab to chemotherapy did not increase neutropenia, diarrhoea, or mucositis. INTERPRETATION: The addition of edrecolomab to fluorouracil and folinic acid in the adjuvant treatment of resected stage III colon cancer does not improve overall or disease-free survival, and edrecolomab monotherapy is associated with significantly shorter overall and disease-free survival than fluorouracil and folinic acid and is therefore an inferior treatment option. Edrecolomab is well tolerated and its addition to fluorouracil and folinic acid does not increase the toxicity of chemotherapy.