Prognostic Significance of Pretreatment Immune Cell Infiltration in Muscle Invasive Bladder Cancer Treated with Definitive Chemoradiation: Analysis of NRG RTOG 0524 and 0712

PURPOSE/OBJECTIVE(S)

Chemoradiation therapy (CRT) is an organ conserving approach in the treatment of locally advanced bladder cancer. Chemoradiation is thought to potentially result in immunogenic stimulation, and bladder cancer is often a tumor with high immune cell infiltration. Thus, we aimed to profile the tumor immune microenvironment of bladder cancer and identify prognostic immune biomarkers for CRT response by profiling tumor samples from NRG/RTOG 0524 and 0712, two prospective trials of CRT in muscle invasive bladder cancer (MIBC).

MATERIALS/METHODS

Pretreatment tissue samples from both trials were profiled using Cofactor Genomics ImmunoPrism, an RNA sequencing assay that uses gene expression profiles to quantify immune cell populations in the tumor microenvironment (TME). Differential gene expression was estimated for different immune cell type proportions across samples. Kaplan-Meier survival analysis and log rank tests were performed to evaluate differences in overall survival (OS) stratified by genes influenced by immune cell proportions or genes associated with immune response signatures.

RESULTS

A total of 70 samples (43 from RTOG 0524 and 27 from RTOG 0712) underwent analysis using the ImmunoPrism assay. Immune cell proportions were as follows: CD8 T cells: median 1.2%, CD4 T cells: median 0.8%, Treg cells: median 9.2%, CD19 B cells: median 5.1%, M2 macrophages: median 0.8%, M1 macrophages: median 0%. Unbiased clustering based on gene expression profiles driven by immune cell proportions demonstrated two groups: cluster 1 with a low percentage of immune cells and shorter OS (median 31 months) and cluster 2 with a high percentage of immune cells and longer OS (median 101 months, p = 0.036). Higher expression of genes associated with T cell infiltration (CD8A and ICOS) was associated with improved OS (104 vs 35 months, p = 0.028, HR = 0.48 (0.25 - 0.94), p = 0.031) as was higher expression of IDO1, which is associated with the interferon gamma pathway (104 vs 35 months, p = 0.042, HR = 0.49 (0.24 - 0.99), p = 0.046).

CONCLUSION

Bladder tumors have a wide range of immune cell infiltration in the TME. Increased immune cell proportions are prognostic for OS following CRT, as well as a higher expression of genes associated with T cell infiltration interferon gamma signaling. These findings have implications for the integration of immunotherapy in the definitive management of MIBC; and can be explored further in the ongoing NRG/SWOG 1806 trial.

Neurologist Attitudes on Practicing in Hawai'i

There is a shortage of neurologists nationwide, and the demand for neurologists is expected to increase in the upcoming years while the pool of practicing neurologists dwindles. Per Hawai'i Neurological Society, there were 44 practicing neurologists in the state of Hawai'i in 2019, representing a shortage of approximately 28 neurologists. Considering that Hawai'i is geographically, demographically, and culturally distinct compared to other states, a concern is that practicing neurology in Hawai'i poses unique challenges that may contribute to the low numbers of neurologists. An anonymous online survey was sent via email to all members of the Hawai'i Neurological Society from February 2019 to June 2019, inquiring about aspects of their practice they considered unique to Hawai'i. Twenty-three neurologists completed the survey, representing 52% of Hawai'i's neurology workforce. One neurologist completed a portion of the survey. Twenty-five percent of participants were born and raised or completed their medical education in Hawai'i. Self-reported reasons for practicing in Hawai'i included family, lifestyle, and patient population despite financial challenges and limited resources and opportunities. Participants suggested introducing a mandatory neurology rotation for Hawai'i medical students and creating an instate neurology residency program to combat the growing neurologist shortfall in Hawai'i. This survey identified local strengths and challenges in the field of neurology, potential ways to improve the practice environment in Hawai'i, and neurologists' perspectives on ways to address the neurology shortage.

Significance of epitrochlear lymph node involvement in Hodgkin disease

BACKGROUND

Epitrochlear involvement in Hodgkin disease (HD) is a rare event, with only limited data available describing this unique presentation, its treatment, and long term outcome.

METHODS

Between 1968 and 1997, 1180 patients with clinical stage (CS) IA-IIB HD were treated at the Harvard Longwood Area Hospitals, among whom 11 were identified to have presented with epitrochlear lymphadenopathy (1%). Together with 6 CS III-IV patients also with clinically involved epitrochlear lymph nodes at diagnosis, these 17 patients form the basis of the current study. The clinical characteristics, histopathologic distribution, and treatment details are described. Two radiation therapy techniques were used: the "single field" and "separate-field" techniques. The median dose to the epitrochlear region was 3600 centigrays. Survival outcome was calculated by the Kaplan-Meier method. The median follow-up was 17 years.

RESULTS

The actuarial 15-year freedom from recurrence, cause specific survival, and overall survival (OS) rates for the 17 patients were 70%, 88%, and 70%, respectively. Among the CS IA-IIB patients, the 15-year OS rates of the 1169 patients and 11 patients without and with epitrochlear involvement were 80% and 90%, respectively. Two of the 11 CS IA-IIB and 3 of the 6 CS III-IV patients experienced recurrence. None of the recurrences involved the epitrochlear or ipsilateral brachial region regardless of the treatment technique, and no complications from the local radiation therapy were observed.

CONCLUSIONS

Feasible and effective radiation therapy techniques are available for patients with HD with epitrochlear involvement. If appropriately treated, the prognosis of patients with this unique presentation appears to be similar to that of other HD patients.

Enhanced potency of daunorubicin against multidrug resistant subline KB-ChR-8-5-11 by a pulsed magnetic field

Tumor cell resistance to many unrelated anticancer drugs is a major obstacle during cancer chemotherapy. One mechanism of drug resistance is thought to be due to the efflux of anticancer drugs caused by P-glycoprotein. In recent years, magnetic fields have been found to enhance the potency of anticancer drugs, with favorable modulation of cancer therapy. In this study, KB-ChR-8-5-11, a multidrug resistant (MDR) human carcinoma subline, was used as a model to evaluate the ability of pulsed magnetic fields (PMF) to modulate the potency of daunorubicin (DNR) in vivo and to determine the appropriate order of exposure to drugs and PMF using an in vitro cytotoxicity assay. Solenoid coils with a ramped pulse current source were used at 250 pulses per second for both in vivo and in vitro experiments. For the in vivo study, KB-ChR-8-5-11 cells were inoculated into thymic Balbc-nu/nu female mice. Treatment was begun when the average tumor volume reached 250-450 mm3. Treatment consisted of whole body exposure to PMF for one hour, followed immediately by intravenous (i.v.) injection of 8 mg/kg DNR designated as day 0, and repeated on days 7 and 14. Among the various groups, significant differences in the tumor volume were found between PMF + saline and PMF + DNR groups (p = 0.0107) at 39 days and 42 days (p = 0.0101). No mice died in the PMF alone group, and no toxicity attributable to PMF was found during the experimental period. For the in vitro studies, the sulforhodamine blue (SRB) cytotoxicity assay was used to determine the effect of the sequence which cells are exposed to PMF and/or DNR. Cells were exposed to PMF either before (pre-PMF) or after (post-PMF) drug was added. Results showed that the IC50 was significantly different between controls and pre-PMF + DNR groups (P = 0.0096, P = 0.0088). The IC50 of the post-PMF + DNR group was not found to be significantly different from control groups. Thus, the data in this report demonstrates that PMF enhanced the potency of DNR against KB-ChR-8-5-11 xenograft in vivo, while the efficacy of DNR was potentiated in vitro by PMF exposure only when PMF exposure occurred in the presence of drug. The data in vitro suggest that the mechanism by which PMFs modulate DNR's potency may be by inhibition of the efflux pump, P-glycoprotein. Further work to determine conditions for maximum modulation of drug potency by PMFs is warranted.

Effects of diethyl spermine analogues in human bladder cancer cell lines in culture

The biochemical and antiproliferative effects of two recently developed N-alkylated analogues of naturally-occurring polyamines, N1,N14-diethylhomospermine (DEHSPM) and N1,N11-diethylnorspermine (DENSPM), were investigated in two human transitional cell carcinoma (TCC) lines, T24 and J82. Parallel studies with the ornithine decarboxylase enzyme inhibitor alpha-difluoromethylornithine (DFMO) were included for comparison. DENSPM displayed greater antiproliferative activity than DEHSPM in both TCC cell lines. Both analogues were strikingly more potent than DFMO. DEHSPM and DENSPM suppressed the activity of the major biosynthetic enzymes, ornithine decarboxylase and S-adenosylmethionine decarboxylase. However, differences in the resulting polyamine depletion suggest that the substantial antiproliferative activity of these analogues may result from mechanisms other than polyamine depletion. The greater polyamine depletion seen with DENSPM is thought to result from its striking induction of spermidine/spermine N1-acetyltransferase. DENSPM is an attractive agent for further preclinical and clinical development, possibly as a chemopreventive agent, in TCC of the bladder.

Regulatory and antiproliferative effects of N-alkylated polyamine analogues in human and hamster pancreatic adenocarcinoma cell lines

N-Alkylated polyamine analogues have been shown to exert antiproliferative effects in several tumor models, with the bis-ethyl derivatives exerting the greatest suppression of polyamines by virtue of down-regulation of the polyamine biosynthetic enzymes. Pancreatic adenocarcinoma presents a challenge both clinically and experimentally due to its inherent resistance to conventional therapy, which results in its having the worst 5-year survival rate of all cancers. We have previously shown that N1,N12-bis(ethyl)spermine (BESPM) is much more potent than the polyamine enzyme inhibitor alpha-difluoromethylornithine (DFMO) against pancreatic adenocarcinoma cell lines. In the present study, we compared the biochemical and antiproliferative effects of two N-alkylated polyamine analogues, N1,N14-bis(ethyl)homospermine (BEHSPM) and N1,N11-bis(ethyl)norspermine (BENSPM) in two human pancreatic ductal adenocarcinoma cell lines, PANC-1 (poorly differentiated) and BxPC-3 (moderately well-differentiated), and in the WD PaCa (well-differentiated ductal) hamster cell line. BENSPM displayed greater antiproliferative activity in the human pancreatic cancer cell lines, whereas BEHSPM was more potent in the hamster cell line. Both BEHSPM and BENSPM suppress the activity of the major biosynthetic enzymes ornithine decarboxylase and S-adenosylmethionine decarboxylase. However, the induction of polyamine depletion in the human cell lines was only modest for BENSPM and minimal for BEHSPM, which suggests that the substantial antiproliferative activity of these analogues may result from mechanisms other than polyamine depletion. The somewhat greater polyamine depletion seen following treatment with BENSPM is thought to result from its striking induction of spermidine/spermine N1-acetyltransferase. The biochemical and antiproliferative activity of BENSPM makes it an attractive agent for further preclinical and clinical development, especially in pancreatic cancer.

Antitumor effects of N-alkylated polyamine analogues in human pancreatic adenocarcinoma models

Adenocarcinoma of the pancreas presents a formidable challenge both experimentally and clinically, whereby effective anticancer therapy is lacking. We have recently explored a relatively new class of antitumor agents in pancreatic cancer cell lines and have found the bis-ethyl derivatives of spermine to show considerable promise. In the present paper, we report the results of in vivo studies demonstrating the antitumor activity of two of these N-alkylated analogues, N1,N14-bis(ethyl)homospermine (BEHSPM) and N1,N11-bis(ethyl)norspermine (BENSPM) in athymic (nude) mouse xenografts of two human pancreatic ductal adenocarcinoma cell lines, PANC-1 (poorly differentiated) and BxPC-3 (moderately well-differentiated). BENSPM was found to exert greater antitumor activity in vivo than either BEHSPM or other conventional agents, largely because higher doses could be given due to its lower toxicity to mice. BENSPM shows greater activity than any other agent we have thus far tested against our pancreatic-cancer models. Optimal schedules of administration have yet to be determined. Nevertheless, of the analogues tested, BENSPM presently appears to be the analogue of choice for further development.

Inhibitory effects of a calcium antagonist on ornithine decarboxylase induction in pancreatic cancer cell lines

The calcium channel blocker verapamil has been previously shown to augment the chemosensitivity of pancreatic adenocarcinoma cell lines to doxorubicin by mechanisms other than changes in the intracellular accumulation, retention, or metabolism of doxorubicin. Because of our interest in polyamine biosynthesis and metabolism and the known involvement of calcium in the induction of ornithine decarboxylase (ODC) by serum refeeding of cultured cells, the effects of verapamil on the serum-stimulated ODC activity in two hamster pancreatic adenocarcinoma cell lines were examined. In plateau phase well-differentiated (WD) PaCa and poorly differentiated (PD) PaCa cells, a dose-dependent inhibition of the 4-h serum induction of ODC was seen at concentrations of 1, 5, and 10 microM verapamil. At the higher concentrations of verapamil, the inhibition of ODC induction was comparable to that achieved with 5 mM alpha-difluoromethylornithine (DFMO, a specific enzyme inhibitor of ODC) and greater than that seen with 2 mM EGTA plus calcium-depleted serum. Log phase PD PaCa cells, included for comparison, showed less ODC induction with serum and lesser degrees of inhibition of the response to serum refeeding with verapamil, DFMO, and calcium depletion. No direct inhibition of the ODC enzyme was found when verapamil was added at the time the activity was measured. Based on our present data, a possible influence of intracellular calcium pools in the verapamil effect on ODC activity is unclear. Nevertheless, the present findings suggest that verapamil's effects on cytotoxicity may be mediated (at least in part) by inhibition of the serum-mediated induction of ODC.

Cellular pharmacology of doxorubicinol alone and combined with verapamil in pancreatic cancer cell lines

The cellular accumulation/retention and cytotoxicity of doxorubicinol (DOXOL) were determined in three pancreatic cancer cell lines, which display primary or intrinsic resistance to doxorubicin (DOX). The studies reported here were performed in the presence and in the absence of verapamil, a calcium antagonist which we have previously shown to potentiate the cytotoxicity of DOX in our panel of pancreatic cancer cell lines. The accumulation/retention of DOXOL, as assayed by HPLC, was not enhanced by 6.6 microM verapamil in these cell lines. No aglycone metabolites were detected in any of the cell lines. The DOXOL cytotoxicity was enhanced 2.0 to 2.9-fold in two of the cell lines. The dose-related accumulation of DOX, as compared to that of DOXOL, was 7.5 to 10-fold greater at 0.1 microM, 3.6 to 6.5-fold greater at 1.0 microM, and 1.9 to 2.4-fold greater at 10 microM. In contrast, for two of our more sensitive cell lines, DOX was 25 to 27 times more cytotoxic than DOXOL. The present study suggests that (a) verapamil's effect on the cytotoxicity of DOX is not mediated by changes in the accumulation/retention nor the cytotoxicity of DOXOL; (b) metabolism of DOXOL does not influence its cytotoxicity nor that of DOX; and (c) DOXOL'S lower antitumor potency as compared to DOX cannot be fully explained by differences in intracellular accumulation.

Dissociation of the verapamil-induced enhancement of doxorubicin's cytotoxicity from changes in cellular accumulation or retention of doxorubicin in pancreatic cancer cell lines

The poor response of pancreatic adenocarcinoma to conventional chemotherapy has prompted us to search for innovative treatment approaches. Verapamil, a calcium channel blocker, has been reported to increase the doxorubicin sensitivity of several tumor models with acquired resistance, often in association with decreased efflux resulting in increased net accumulation/retention of doxorubicin. The cell lines used in the present study, PANC-1 of human origin and two cell lines of hamster origin, WD PaCa and PD PaCa, exhibit primary or intrinsic doxorubicin resistance. Verapamil caused a dose-dependent enhancement of doxorubicin's cytotoxicity in the pancreatic cancer-cell lines studied. In PANC-1, WD PaCa, and PD PaCa, respectively, the enhancement was 10.4-, 281.01-, and 15.8-fold at 6.6 microM verapamil and 1.1-, 8.8-, and 6.3-fold at 1.0 microM verapamil. Of note is the finding that the verapamil enhancement of sensitivity to doxorubicin was most marked in our most drug resistant cell line (WD PaCa). However, minimal to no effect on the accumulation or retention of doxorubicin was documented. In addition, the intracellular metabolism of doxorubicin was not found to be altered by verapamil. The present study raises questions concerning the nature and mechanism(s) of primary anthracycline resistance.

Modulation of polyamine biosynthesis and transport by oncogene transfection

The effects of oncogene expression on phenomena related to polyamine metabolism were examined in Rat-1 cells stably transfected with EJ2-ras or N-myc oncogenes. In ras-transfected cells, ornithine decarboxylase activity was about 12-times higher than in either the parent or N-myc-transfected cell lines. By contrast, polyamine uptake was markedly increased in N-myc-transfected cells, as indicated by their enhanced sensitivity to the antiproliferative and enzyme regulatory effects of the polyamine analog, N1, N12-bis(ethyl)spermine (BESm), their intracellular accumulation of BESm and by their increased sensitivity to the growth inhibitory effects of methylglyoxalbis(guanylhydrazone)--another analog which utilizes the polyamine transport mechanism. These associations between N-myc and ras expression and critical aspects of polyamine metabolism suggest a possible role for the latter in facilitating the growth promoting properties of these oncogenes.

Doxorubicin cardiotoxicity may be caused by its metabolite, doxorubicinol

Doxorubicin (former generic name, adriamycin), a highly effective anticancer drug, produces cardiotoxicity, which limits its therapeutic potential. The mechanism of this cardiotoxicity has remained elusive. Our data suggest that this toxicity could involve doxorubicinol, the primary circulating metabolite of doxorubicin. Doxorubicinol was markedly more potent than doxorubicin at compromising both systolic and diastolic cardiac function. Similarly, doxorubicinol was much more potent than doxorubicin at inhibiting the calcium pump of sarcoplasmic reticulum [ATP phosphohydrolase (Ca2+-transporting), EC 3.6.1.38], the Na+/K+ pump of sarcolemma [ATP phosphohydrolase (Na+/K+-transporting), EC 3.6.1.37], and the F0F1 proton pump of mitochondria [ATP phosphohydrolase (H+-transporting, EC 3.6.1.34]. Our finding that this highly toxic metabolite was produced by cardiac tissue exposed to doxorubicin suggests that doxorubicinol could accumulate in the heart and contribute significantly to the chronic cumulative cardiotoxicity of doxorubicin therapy. Our observation that doxorubicin was more potent than doxorubicinol in inhibiting tumor cell growth in vitro suggests that the cardiotoxicity of doxorubicin is dissociable from its anticancer activity.

Schedule-dependent interaction of alpha-difluoromethylornithine and cis-diamminedichloroplatinum(II) against human and hamster pancreatic cancer cell lines

The interaction of cis-diamminedichloroplatinum (cisplatin) and alpha-difluoromethylornithine (DFMO) has been previously shown by us to be roughly additive in enhancing the growth-inhibitory effects of cisplatin and by another group of investigators to be antagonistic. Since two different schedules of administration were used, we sought to investigate systematically the role of schedule dependence in the interaction of cisplatin and DFMO in a panel of pancreatic adenocarcinoma cell lines (PANC-1, of human origin, and WD PaCa and PD PaCa, both of hamster origin). Dose-effect relationships of single drug alone and in combination were analyzed by the median-effect principle and by the combination indices for the quantitation of synergism or antagonism with the aid of a microcomputer. Pre-cisplatin administration of DFMO for 2 or 5 to 6 days at concentrations of 50 or 100 micrograms/ml (0.21 or 0.42 mM) was found to antagonize the effects of cisplatin to various degrees in the cell lines. In contrast, whenever post-cisplatin DFMO was administered, marked enhancement, which was synergistic in most instances, of cisplatin's inhibition of colony formation was found. Thus, the interaction of cisplatin and DFMO is felt to be schedule dependent with deleterious effects found only when DFMO is administered prior to and not following cisplatin. Furthermore, the combination shows promise as an approach to overcoming drug resistance in pancreatic cancer.

Experimental method for the hyperthermic treatment of cells in tissue culture: initial application to pancreatic cancer cells

Hyperthermia is attractive as a potential adjunctive modality in the treatment of cancer, especially those cancers that are more resistant to conventional modalities. In the present study, we characterized the response of two pancreatic cancer cell lines to hyperthermia alone. In so doing, we utilized and characterized a novel exposure system that heats by 915-MHz continuous wave microwave (MW) radiation, with microprocessor control of the power input via temperature monitoring of the sample and simultaneous visualization and recording of temperature parameters. Samples, consisting of cells in 25-cm2 culture flasks with 10 ml of medium, were exposed to MWs in a stripline for 1 h at MW-induced temperatures of 37, 41.5, 42.5, 43.5, or 44.5 degrees C. The specific absorption rate was 132 W/kg for all temperatures. In addition, 37 degrees C waterbath controls were concurrently run. The colony formation assay was used to assess cytotoxicity. No significant difference was found between 37 degrees C waterbath and 37 degrees C MW controls. Significant differences in the thermosensitivity of the two cell lines were found, with the most drug-sensitive cell line showing the greatest thermosensitivity. However, hyperthermia alone was not very effective as a single cytotoxic modality in either cell line. The MW-hyperthermia-induction system provided precise, automated temperature control (+/- 0.2 degrees C), and ease of utilization and data management.

Different zeta globin gene deletions among black Americans

Four types of chromosomes with a deletion between the human embryonic zeta and psi zeta globin genes were identified among 2.8% of 321 Black Americans from Georgia. Two deletions of approximately 11 kb which differed by about 300 bp occurred on chromosomes with or without a polymorphic Xba I site 5' to the zeta globin gene [(X+) or (X-)]. The deletions are identifiable in Xba I digests of genomic DNA using an alpha or a zeta globin gene probe which yield fragments of 23 kb from (X+)-zeta alpha alpha chromosomes or 27 kb from (X-)-zeta alpha alpha chromosomes. Digestion with other enzymes and probing with both alpha and zeta probes gave fragments typical of the two zeta globin gene deletions previously identified in Polynesians. Among Black Americans, these zeta globin gene deletions have been found in combination with alpha globin gene deletions in trans but not in cis. Homozygotes have not been found. Hematologic data on carriers of the zeta globin gene deletions in association with Hb AS, SS, and SC suggest that these deletions have no effect on the function of the adult alpha globin genes.

Combined effects of alpha-difluoromethylornithine and doxorubicin against pancreatic cancer cell lines in culture

Pancreatic adenocarcinoma presents a clinical and experimental challenge because of its relative resistance to conventional modes of therapy. The present study explores a novel, biologically based approach to enhancing its chemosensitivity and to overcoming its chemoresistance in a panel of pancreatic adenocarcinoma cell lines (two human lines: PANC-1 and COLO-357; and two hamster lines: WD PaCa and PD PaCa). Difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (ODC) that produces antiproliferative effects by polyamine depletion, was combined with the cytotoxic agent doxorubicin (DOX) in vitro. The inhibitory effects of DFMO were cytostatic and roughly additive to those of DOX. Although the response to the combination varied as a function of the cell lines studied and the response to DFMO as a single agent, all cell lines studied showed some increased inhibition with the combination. The most striking enhancement was seen in our most DOX-resistant cell line, WD PaCa, and also in PANC-1, a relatively sensitive cell line. Thus, the combination of DFMO and DOX shows promise as an experimental approach to the problem of drug resistance and the limited chemosensitivity of pancreatic cancer.

Comparison of the cellular pharmacology of doxorubicin in resistant and sensitive models of pancreatic cancer

The cellular accumulation and retention of doxorubicin (ADR) was investigated in two models of pancreatic adenocarcinoma, which differ markedly in their sensitivity to ADR. In vitro studies revealed that the relatively resistant cell line, WD PaCa (or well-differentiated pancreatic adenocarcinoma of the Syrian hamster), actually had higher ADR cellular levels than the sensitive cell line, PD PaCa (or poorly differentiated pancreatic adenocarcinoma of the Syrian hamster). While the efflux of ADR from WD PaCa was greater, the overall retention of ADR by WD PaCa was comparable to PD PaCa. These results failed to document differences in accumulation or retention of ADR capable of explaining the difference in the sensitivity of the cell lines to ADR and indicate the need to search beyond attainable drug concentrations for mechanisms of primary ADR resistance.

Inhibition of growth of human or hamster pancreatic cancer cell lines by alpha-difluoromethylornithine alone and combined with cis-diamminedichloroplatinum(II)

A major problem in the therapy of pancreatic adenocarcinoma is its inherent resistance to most chemotherapeutic agents. Previously, we have reported that the four pancreatic cancer cell lines studied here have elevated levels of ornithine decarboxylase, a growth-regulating enzyme, and further that the degree of elevation tends to parallel the degree of chemoresistance. On the basis of these prior findings, we investigated the effects of alpha-difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase, alone and in combination with cis-diamminedichloroplatinum(II) (cisplatin), to which two of the four cell lines display relative resistance. The cell lines studied were: two of human origin, PANC-1 and COLO-357; and two of hamster origin, WD PaCa and PD PaCa. Colony formation (clonogenic) assays were used to evaluate drug effects. Cells were exposed continuously to DFMO in medium. For the combined treatments, cells were exposed to cisplatin for 1 hr, washed, and then plated in DFMO-containing medium. The inhibitory effects of DFMO were predominantly cytostatic, were reversible by putrescine, and were roughly additive when combined with cisplatin. Our panel of cell lines responded heterogeneously to DFMO, with PANC-1 and WD PaCa showing the most sensitivity. The combination of DFMO and cisplatin appears to be a promising experimental approach to overcoming drug resistance in pancreatic cancer.

The disposition of the new anthracycline antibiotic, menogarol, in mice

We have investigated the metabolism and disposition, in mice, of 7-con-O-methylnogarol ( menogarol ; 7-OMEN), a new anthracycline antibiotic entering clinical trials. 7-OMEN, dissolved in 0.01 M glucuronic acid, was administered iv to mice (10 mg/kg). At specified times after injection, groups of mice were killed and 7-OMEN and metabolites were assayed in plasma and organs by HPLC. Plasma concentrations of 7-OMEN declined in triexponential fashion. The terminal t1/2 was 10.6 hr; the AUC was 10.13 microM X hr; the apparent Vc was 0.4 liter/m2, and the systemic clearance was 91.2 ml/min/m2. One metabolite, with the same HPLC characteristics as N- demethylmenogarol , was seen in plasma during the first 30 min after injection. 7-OMEN was distributed extensively to all tissues except brain. Initially, pulmonary concentrations of 7-OMEN were 15 times higher than those in any other organ and 30 times higher than those in plasma. Concentrations of 7-OMEN were the most persistent in spleen, kidney, and pancreas, and the least persistent in heart and liver. The AUC for 7-OMEN in organs was the greatest in lungs (605 nmol/g X hr), spleen (522 nmol/g X hr), and pancreas (430 nmol/g X hr), and least in heart (33 nmol/g X hr) and liver (60 nmol/g X hr). Kidneys and skeletal muscles had intermediate AUC values. In liver, two metabolites, one of which had the HPLC characteristics of N- demethylmenogarol , were seen. In other organs, the same metabolites were seen later and in small quantities.

Comparison of in vitro methods for assessing cytotoxic activity against two pancreatic adenocarcinoma cell lines

Several models of pancreatic adenocarcinoma are now available for experimental evaluation of newer chemotherapeutic agents. The present study represents an attempt to develop a rapid in vitro screening technique that would allow prediction of cytotoxic activity (or lack thereof) as reliably as the clonogenic or colony formation assay. To this end, seven drugs (cisplatin, dactinomycin, doxorubicin, 5-fluorouracil, menogarol, mitoxantrone, and streptozocin) were tested against two pancreatic adenocarcinoma cell lines using a standard colony formation assay and a 24-hr microcytotoxicity assay. The cell lines tested were PANC-1, of human poorly differentiated pancreatic adenocarcinoma origin, and WD PaCa, of hamster well-differentiated pancreatic adenocarcinoma origin. The dose-survival curves and resulting determinations of drug dose (microgram/ml/1-hr exposure) at which there is a 50% inhibition of survival as compared to controls were compared for the two cell lines by each assay system. Lack of correlation of the two assays and considerable interdrug and inter-cell line variation were found. In addition, the microcytotoxicity assay was felt to underestimate the in vitro drug sensitivity of PANC-1 to three drugs (dactinomycin, doxorubicin, and mitoxantrone) and of WD PaCa to two drugs (5-fluorouracil and mitoxantrone). Despite the possible utility of the microcytotoxicity assay with other experimental models, the colony formation assay technique appears to provide the most reliable in vitro assessment of antineoplastic activity for pancreatic adenocarcinoma cell lines and should continue to be the standard to which other assay systems are compared.

Ornithine decarboxylase enzyme activity in human and hamster pancreatic tumor cell lines

We measured ornithine decarboxylase (ODC) enzyme activity, protein and DNA levels in 4 pancreatic cancer cell lines, 2 derived from human tumors (COLO-357 and PANC-1) and 2 derived from hamster tumors (WDPaCa and PDPaCa). We measured the parameters in confluent stage conditions and in log-growth phase. We report that the enzyme levels in all cell lines are elevated with respect to normal pancreatic tissue. Half-life studies of ODC in the PDPaCa cell line indicate a 3-fold increase in half-life.

Chemotherapy of pancreatic adenocarcinoma: initial report on two transplantable models in the Syrian hamster

Experimental evaluation of chemotherapy of pancreatic cancer has been limited by the lack of suitable animal models, which have only recently become available. The present study is the first report on the chemosensitivity of two transplantable animal models of pancreatic adenocarcinoma. The single-agent antitumor activity of 5-fluorouracil, cyclophosphamide, mitomycin C (MMC), methotrexate, actinomycin D, vincristine, and two dose levels of Adriamycin (ADR) were tested against established palpable tumors of well-differentiated pancreatic ductal adenocarcinoma (WD PaCa), a solid tumor model of the Syrian hamster. None of the agents or dosages of ADR were effective against palpable WD PaCa tumors. ADR, MMC, streptozotocin, and the combination of 5-fluorouracil, ADR, and MMC were similarly ineffective when administered 1 week after WD PaCA implantation, while tumors were still nonpalpable. The behavior of poorly differentiated pancreatic ductal adenocarcinoma (PD PaCa), an ascitic model of the Syrian hamster, was studied for comparison. In vivo, with survival as the end point, PD PaCa is markedly sensitive to ADR, perhaps weakly sensitive to MMC, and resistant to streptozotocin. In vitro clonogenic assays from cultured PD PaCa and WD PaCa confirmed the pattern of response seen in vivo. The data suggest that these recently developed pancreatic cancer models can be profitably used and compared, both in vivo and in vitro, as examples of relatively chemotherapy resistant (WD PaCa) and more sensitive (PD PaCa) tumor models.

Microwave treatment of intracerebral L1210 leukemia: schedule-dependent partial reversal of the effects of methotrexate

One-GHz microwave (MW) irradiation at a power density of 5 mW/cm2 was combined with methotrexate (MTX) in an attempt to treat more effectively central nervous system (CNS) L1210 leukemia in DBA/2J mice. When mice with CNS leukemia were treated with the combination of MW and MTX, there was no improvement in survival compared with a group of animals treated with MTX alone; however, the group that received MTX before the MW exposure had a significantly reduced survival time compared with the group treated with MTX alone or with the group to which MTX was administered after MW.

Inhibition of DNA synthesis and enhancement of the uptake and action of methotrexate by low-power-density microwave radiation in L1210 leukemia cells

We have studied the effects of low-power-density microwave (MW) radiation (continuous and pulsed wave with average power density of 10 milliwatts/sq cm and range of 5 to 50 milliwatts/sq cm; frequency, 1.0 GHz) on the uptake and action of methotrexate (MTX), the inhibition of DNA synthesis in L1210 murine leukemia cells in vitro, and the MTX treatment of mice bearing this leukemia. Using short-term tissue culture techniques, MTX concentrations of 0.2 microM, and MW exposure times of 20 min, we have found that continuous-wave low-power-density MW irradiation enhances the uptake of [3H]MTX as compared to nonirradiated controls. The enhancement is observed in only a small range of power densities (5 to 25 milliwatts/sq cm) and is in an inverted-U-shaped relationship. MW irradiation alone has an inhibitory effect on the [3H]deoxyuridine incorporation into DNA. Compared to cell suspensions treated with MTX alone, groups treated with MW irradiation followed by MTX exhibit an augmentation of inhibition of DNA synthesis as measured by [3H]deoxyuridine incorporation. Combined treatment of L1210-bearing mice with MW irradiation and MTX in vivo prolonged the duration of survival over that of animals treated with MTX alone, indicating a greater killing of leukemia cells. These results suggest that the therapeutic index of MTX may be improved by the use of MW irradiation at low power densities.