Survival Time Of Tumor-bearing Animals Research Articles

Pre-clinical efficacy of CD20-targeted chimeric antigen receptor T cells for non-Hodgkin's lymphoma

BackgroundA 4-1BB/CD3-ζ-costimulated CAR-T against CD20 (CAR-T20) was subjected to a systemic efficacy evaluation in a cell co-culture model, and NOD-SCID IL-2 receptor gamma null mice (short for NSG mice) were xenografted with human Burkitt's lymphoma Raji cells.MethodsCAR-T20 cells were incubated with target cells (K562, K562 CD20 or Raji cells) at ratios of 10:1 and 5:1 for 24 h, and the killing rate was estimated by an LDH cytotoxicity assay. To evaluate the effect of CAR-T20 on the survival time of tumor-bearing animals, 30 NSG mice were employed, and Raji-Luc cells (5 × 105 cells per mouse) were administered prior to CAR-T20 administration. The survival time, optical intensity of Raji-Luc cells, clinical symptoms, and body mass of the animals were observed. Another 144 male NSG mice were employed to investigate the proliferation and antitumor effects of CAR-T20. Human cytokine and murine cytokines were detected at 1, 7, 14, 21, 28, 42, 56 and 90 days post-CAR-T administration, while biochemistry index analysis, T-cell and CAR-T-cell detection in peripheral blood, and histopathological examination were performed at 14, 28, 56 and 90 days post-administration.ResultsCAR-T20 cells had a specific killing effect on CD20-expressing cells in vitro. At a dose of 1 × 106 per mouse or above, CAR-T20 prolonged the median survival time from 14 days to more than 3 months, inhibited the proliferation of Raji cells in mice, and alleviated the clinical manifestations and weight loss caused by the Raji-Luc cell load. CAR-T20 at a dose of 2 × 106 per mouse or above inhibited the proliferation of Raji cells in mice for up to 111 days post-administration without recurrence. The numbers of T cells and CAR-T cells in the animals administered CAR-T20 increased significantly when Raji cells were markedly proliferated and subsequently decreased when Raji cells were predominantly inhibited. CAR-T20 increased human IFN-γ, murine TNF and murine IL-6 levels and decreased human IL-10 levels in tumor-bearing mice. The incidences of xenografted tumors in organs/tissues were also reduced effectively by CAR-T20.ConclusionThe effective dose of CAR-T20 in mice starts from 1 × 106 per mouse, equivalent to a clinical dose of 5 × 106/kg. Together, our data support the clinical translation of CAR-T20 for R/R B-cell NHL patients.

CircPIK3C2A Facilitates the Progression of Glioblastoma via Targeting miR-877-5p/FOXM1 Axis.

Glioblastoma is a rare yet lethal type of tumor that poses a crucible for the medical profession, owing to its rapid proliferation and invasion resulting in poor prognosis. Circular RNAs (circRNAs), a subclass of regulatory RNAs, are implicated in the regulation of cancerous progression. This study aims to investigate the roles and underlying mechanism of circPIK3C2A in regulating proliferation and invasion of glioblastoma. qRT-PCR assays showed that the expression level of circPIK3C2A was aberrantly higher in glioblastoma cell lines, in comparison with that in normal glia cells. The ectopic expression of circPIK3C2A promoted the proliferation, invasion and clonal formation of glioblastoma cells, while circPIK3C2A loss-of-function exerted exactly the opposite biological effects on the cells. The construction of subcutaneous xenograft tumor model in nude mice indicated that circPIK3C2A loss-of-function effectively diminished tumor load in vivo and prolonged the survival time of tumor-bearing animals. Luciferase reporter assay confirmed the interaction among circPIK3C2A/miR-877-5p and FOXM1. CircPIK3C2A function as competitive endogenous RNA via sponging miR-877-5p through certain binding sites, thereby modulating the expression of FOXM1. Our results collectively indicate that circPIK3C2A functions as ceRNA by mediating miR-877-5p/FOXM1 axis, providing a novel perspective of applying CircPIK3C2A in the clinical intervention of glioblastoma in the future.

Mathematical Model of Muscle Wasting in Cancer Cachexia.

Cancer cachexia is a debilitating condition characterized by an extreme loss of skeletal muscle mass, which negatively impacts patients’ quality of life, reduces their ability to sustain anti-cancer therapies, and increases the risk of mortality. Recent discoveries have identified the myostatin/activin A/ActRIIB pathway as critical to muscle wasting by inducing satellite cell quiescence and increasing muscle-specific ubiquitin ligases responsible for atrophy. Remarkably, pharmacological blockade of the ActRIIB pathway has been shown to reverse muscle wasting and prolong the survival time of tumor-bearing animals. To explore the implications of this signaling pathway and potential therapeutic targets in cachexia, we construct a novel mathematical model of muscle tissue subjected to tumor-derived cachectic factors. The model formulation tracks the intercellular interactions between cancer cell, satellite cell, and muscle cell populations. The model is parameterized by fitting to colon-26 mouse model data, and the analysis provides insight into tissue growth in healthy, cancerous, and post-cachexia treatment conditions. Model predictions suggest that cachexia fundamentally alters muscle tissue health, as measured by the stem cell ratio, and this is only partially recovered by anti-cachexia treatment. Our mathematical findings suggest that after blocking the myostatin/activin A pathway, partial recovery of cancer-induced muscle loss requires the activation and proliferation of the satellite cell compartment with a functional differentiation program.

PEGylated reduced-graphene oxide hybridized with Fe3O4 nanoparticles for cancer photothermal-immunotherapy.

Photoimmunotherapy has attracted much attention recently for the treatment of metastatic tumors. The development of smart nanocomposites for imaging-guided therapies is needed to improve the efficacy of cancer treatment. Herein, a PEGylated nanocomposite was developed for photothermal-immunotherapy. In particular, this nanocomposite was formulated by hybridizing Fe3O4 nanoparticles (FNPs) with reduced-graphene oxide (rGO) through electrostatic interaction, modified by PEG-NH2 on the surface of FNPs/rGO. The FNPs/rGO-PEG nanocomposites are excellent agents for photothermal therapy (PTT) under irradiation by an 805 nm laser. This nanocomposite could promote the activity of the host antitumor immune response efficiently because of the reduction of tumor-associated macrophages by the incorporation of FNPs. In our experiments, we observed FNPs/rGO-PEG based PTT induced immunogenic cell death accompanied by the release of danger-associated molecular patterns. We also found that FNPs/rGO-PEG + laser irradiation of animal tumors could activate dendritic cells (DCs) in tumor draining lymph nodes. In vivo antitumor studies revealed that FNPs/rGO-PEG nanocomposites, when combined with laser irradiation, could result in desirable photothermal effects and destroy primary tumors. Moreover, intratumoral injection of FNPs/rGO-PEG nanocomposites into 4T1 orthotopic mouse breast tumors, in combination with near-infrared laser irradiation, significantly increased the median survival time of tumor-bearing animals. FNPs/rGO-PEG nanocomposites could also be used for magnetic resonance imaging, which may lead to a MRI-guided photothermal-immunotherapy for metastatic cancers. This study could lead to a cancer treatment strategy that combines PTT with immunotherapies using FNPs/rGO-PEG nanocomposites.

Effect of the autonomic nervous system on cancer progression depends on the type of tumor: solid are more affected then ascitic tumors.

A number of recently published studies have shown that the sympathetic nervous system may influence cancer progression. There are, however, some ambiguities about the role of the parasympathetic nerves in the modulation of growth of different tumor types. Moreover, tumor models used for investigation of the autonomic neurotransmission role in the processes related to the cancer growth and progression are mainly of the solid nature. The knowledge about the nervous system involvement in the modulation of the development and progression of malignant ascites is only fragmental. Therefore, the aim of the present article was to summarize the results of our experimental studies focused on the elucidation of the role of the autonomic nervous system in the modulation of tumor growth in animals. We are summarizing data from studies, in which not only different experimental approaches in order to influence the autonomic neurotransmission, but also different tumor models have been used. Three different types of tumor models, namely solid rat intra-abdominal fibrosarcoma, solid murine subcutaneous melanoma, and rat ascites hepatoma, and three types of interventions have been used in order to modulate the autonomic neurotransmission, specifically chemical sympathectomy, subdiaphragmatic vagotomy, or the electric stimulation of the vagus nerve. We have proved a strong stimulatory effect of the sympathetic nerves on the development and growth in both solid tumors, rat fibrosarcoma as well as murine melanoma, and significant inhibitory impact on the survival time of tumor-bearing animals. The progression of ascites hepatoma in rats was not influenced by chemical sympathectomy. Modulation of parasympathetic signalization by vagotomy or vagal nerve stimulation does not affect fibrosarcoma and ascites hepatoma growth and survival of the tumor-bearing rats. Based on the obtained data, it seems that the solid types of tumors are suitable substrate for the direct action of neurotransmitters released especially from the sympathetic nerves. In contrast, it appears that the malignant ascites are not under the direct autonomic nerves control; however, an indirect action via the immune functions modulation cannot be excluded.

Dimethylsulfoxide excerbates cisplatin-induced cytotoxicity in Ehrlich ascites carcinoma cells.

BackgroundCisplatin (CIS) is a potent antineoplastic agent with high therapeutic efficacy against many kinds of tumors. Its use is limited by its nephrotoxicity. The aim of this work was to minimize cisplatin effective dose and the possible reduction of its severe side effects. The present study was designed to assess the role of sulfur containing agent dimethyl sulfoxide (DMSO) on sensitization of mammary carcinoma, Ehrlich ascites carcinoma (EAC), to the action of cisplatin and at the same time the possible protective effect against cisplatin induced nephrotoxicity in experimental animals.MethodsTo evaluate these effects we have explored the cisplatin effect on the survival time of tumor-bearing animals, tumor weight, cisplatin cellular uptake, apoptosis induction and cell cycle distribution and renal function in presence and absence of DMSO.ResultsCisplatin at dose of 4.5 mg/kg increased the mean survival time of tumor bearing mice to 37 days compared with tumor bearing control mice. Pretreatment of tumor bearing mice with DMSO 50 % (2 ml/kg equal to 1 gm/kg) 2 h. before cisplatin showed a significant increase in their mean survival time 43 days compared to cisplatin treated animals. DMSO pretreatment retained rat’s serum urea and creatinine levels to normal compared to animals treated with cisplatin alone.ConclusionDMSO pretreatment enhanced the cytotoxic activity of cisplatin against the growth of EAC in vivo and showed protective effects against cisplatin-induce nephrotoxicity.

Live attenuated measles virus vaccine induces apoptosis and promotes tumor regression in lung cancer

Although the treatment of lung carcinoma has improved, at least 65% of patients with this tumor succumb to progressive disease. Measles virus oncolytic therapy has been reported to be effective in reducing tumor burden in immunocompetent or nude mice; however, its potential to reduce tumor burden in lung carcinoma remains to be determined. Herein, we report the potent antitumor effects of a live attenuated measles vaccine virus Hu-191 strain (MV) against lung carcinoma. Immunocompetent C57BL/6 mice bearing Lewis lung carcinoma (LLC) cells were treated with MV (1x104 to 1x106 CCID50/ml) once every other day for 10 days. Our results showed that treatment with MV effectively suppressed tumor growth and significantly prolonged the survival time of tumor-bearing animals. Histological examination revealed that the antitumor effects of MV therapy may result from increased induction of apoptosis, tumor necrosis and elevated lymphocyte infiltration. Our data suggest that MV, one of the widely used vaccines in China, has the ability to inhibit the growth of mouse lung carcinoma and may prove useful in the further exploration of the application of this approach in the treatment of human advanced lung cancer.

Antitumor Activity of Glycosylated Molluscan Hemocyanins via Guerin Ascites Tumor

As observed in most molluscan hemocyanins, high-mannose type glycans were identified in hemocyanins from Rapana venosa (RvH), Helix lucorum (HlH) and keyhole limpet (Megatura crenulata). In addition, a glycan with a branching structure containing xylose, fucose and terminal methyl hexose was identified in β-HlH. We have examined the immuno-adjuvant properties of hemocyanins, their derivatives and conjugates associated with the cell mediated immunity in experimental tumor-bearing animals with ascites tumor of Guerin. After immunization of the animals with the experimental vaccine preparations, the highest values of splenic lymphocytes were observed in groups immunized with the conjugates RvH-TAg, β-HlH-TAg and KLH-TAg (42.3%; 40.8% and 40.58%, respectively) than with the native hemocyanins (36.5%; 35.1% and 32.4%, respectively). The immunization of rats with the hemocyanins β-HlH, RvH and KLH and their conjugates, prolonged the median survival time of tumor-bearing animals compared with non-immunized animals (39, 33, 31 and 7 days, respectively). Both hemocyanins β-HlH and RvH activate the immune system of the experimental animals and therefore could be a good alternative for KLH. For this reason they could be included into the composition of non-specific anti-tumor vaccines to enhance their effectiveness.

Effective conversion of irinotecan to SN-38 after intratumoral drug delivery to an intracranial murine glioma model in vivo

Irinotecan (CPT-11), a topoisomerase I inhibitor, is a cytotoxic agent with activity against malignant gliomas and other tumors. After systemic delivery, CPT-11 is converted to its active metabolite, SN-38, which displays significantly higher cytotoxic potency. However, the achievement of therapeutically effective plasma levels of CPT-11 and SN-38 is seriously complicated by variables that affect drug metabolism in the liver. Thus the capacity of CPT-11 to be converted to the active SN38 intratumorally in gliomas was addressed. For in vitro studies, 2 glioma cell lines, U87 and U251, were tested to determine the cytotoxic effects of CPT-11 and SN-38 in a dose-dependent manner. In vivo studies were performed by implanting U87 intracranially into athymic/nude mice. For a period of 2 weeks, SN-38, CPT-11, or vehicle was administered intratumorally by means of an osmotic minipump. One series of experiments measured the presence of SN-38 or CPT-11 in the tumor and surrounding brain tissues after 2 weeks' exposure to the drug. In a second series of experiments, after 2 weeks' exposure to the drug, the animals were maintained, in the absence of drug, until death. The survival curves were then calculated. The results show that the animals that had CPT-11 delivered intratumorally by the minipump expressed SN-38 in vivo. Furthermore, both CPT-11 and SN-38 accumulated at higher levels in tumor tissues compared with uninvolved brain. Intratumoral delivery of CPT-11 or SN-38 extended the average survival time of tumor-bearing animals from 22 days to 46 and 65 days, respectively. These results demonstrate that intratumorally administered CPT-11 can be effectively converted to SN-38 and this method of drug delivery is effective in extending the survival time of animals bearing malignant gliomas.

Differential Proteomic Profiling Identifies Novel Molecular Targets of Paclitaxel and Phytoagent Deoxyelephantopin against Mammary Adenocarcinoma Cells

A major germacranolide sesquiterpene lactone, deoxyelephantopin, identified from Elephantopus scaber L. (known as "Didancao" in Chinese medicine) showed significant antitumor growth and antimetastatic effect on murine mammary adenocarcinoma TS/A cells in vitro and in vivo in mice. Deoxyelephantopin exhibited a superior effect to that of the paclitaxel in prolonging median survival time of tumor-bearing animals in our recent study. To investigate the molecular mechanisms underlying the difference in efficacy between deoxyelephantopin and paclitaxel, we used 2-D DIGE and LC-ESI-MS/MS to profile proteins differentially expressed in the nucleus and cytoplasm of TS/A cells and used the MetaCore database to determine the functional protein networks affected by both treatments. Deoxyelephantopin and paclitaxel treatment produced regulation of molecules involved in proteolysis and calcium ion transport, suggesting the possible effects of both drugs on proteasome and endoplasmic reticulum machinery in TS/A cells. Western blot analysis of marker proteins (e.g., PDI, GRP78, TXND5, caspase-12, caspase-3 and PARP) further verified that induction of endoplasmic reticulum stress was associated with apoptosis induced by both deoxyelephantopin and paclitaxel, but only deoxyelephantopin inhibited proteasomal proteolysis in TS/A cells. The novel effects on targeting ER machinery and suppressing proteasome activity suggest the great potential of deoxyelephantopin for mammary cancer therapy.

Immunization with truncated sequence of Telomerase Reverse Transcriptase induces a specific antitumor response in vivo

To select the MHC-I-binding epitope-rich sequence of mice telomerase reverse transcriptase (mTERT) and study the antitumor immune response induced by truncated TERT through mRNA-transfected dendritic cells (DCs) immunization in mice. The MHC-I-binding epitopes of TERT were predicted using bioinformatics software. The selected sequence of TERT (Truncated mTERT, TERTt, mTERT cDNA 1776 bp-2942 bp encoding 584 aa-969 aa) was cloned from B16 mouse melanoma cells and inserted into pBluescriptIIKS(+) plasmid downstream of the T7 promoter. TERTt RNA was prepared through in vitro transcription. Bone marrow-derived DCs were electroporated with TERTt RNA and used to immunize syngeneic naïve mice. The quantity and cytotoxic activity of TERT-specific cytotoxic T lymphocytes (CTLs) in mice spleen were evaluated using IFN-γ enzyme-linked immunospot (ELISPOT) and Lactate dehydrogenase release assay. The immunoprophylactic effects against TERT positive tumor induced by TERTt RNA transfected DC in vivo were evaluated through an immunized-challenged mouse model. TERTt was cloned and in vitro transcribed into TERTt mRNA. As shown in FCM analysis, the efficiency of DC electroporation is 35.1% (29.7–41.2%). After electroporation, a subtle increase of costimulator and MHC-II molecules were expressed on the cell surface. Immunization of TERTt mRNA transfected DCs induced IFN-γ-secreting CTLs which manifested specific cytotoxic activity against TERT-positive target cells. In a cancer mouse model, vaccination of TERTt mRNA-transfected DCs suppressed the growth of TERT positive tumors (p=0.001) and prolong the survival time of tumor-bearing animals (p=0.029). TERTt evokes an antitumor immune response in vivo which is targeted to TERT. TERTt can be used as an antigeneic sequence to produce anti-TERT tumor vaccine.

Melatonin increases the survival time of animals with untreated mammary tumours: Neuroendocrine stabilization

The aim of this study was to evaluate the therapeutic effect of melatonin, the main hormone of the pineal gland, on rats with advanced and untreated mammary tumours. Mammary tumours were chemically induced in Sprague-Dawley rats with the carcinogen 9,10-dimethyl-1,2-bezanthracene (DMBA). After the appearance of tumours the effect of melatonin (5 mg/ml per rat per day) was then evaluated on the survival time, tumour multiplicity, and tumour volume until the death of the animals. In addition, the variations in prolactin, noradrenaline and adrenaline concentrations, and in the percentage of NK cells were evaluated after one month of the treatment with melatonin. Daily administration of melatonin increased significantly the survival time of tumour-bearing animals (p<0.05 with respect to the control non-melatonin-receiving rats). The increased survival time did not correlate, however, with changes in either tumour multiplicity or tumour growth rate. Animals with mammary tumours exhibited an increase (p<0.05 with respect to healthy animals) in prolactin and catecholamine concentrations. The administration of melatonin stabilized the hormone levels, returning them to those in the basal-healthy animals. Rats with mammary tumours also presented lower percentages of NK cells, which were not increased by the administration of melatonin. The results strongly suggest that melatonin per se is beneficial during advanced breast cancer. It increases survival time, maybe by improving the homeostatic and neuroendocrine equilibrium which is imbalanced during advanced breast cancer.

Reduction of Spontaneous Metastases through Induction of Carbohydrate Cross-Reactive Apoptotic Antibodies

The selective targeting of tumor-associated carbohydrate Ags by the induction of serum Abs that trigger apoptosis of tumor cells as a means to reduce circulating tumor cells and micrometastases would be an advantage in cancer vaccine development. Some plant lectins like Griffonia simplicifolia lectin I and wheat germ agglutinin mediate the apoptosis of tumor cells. We investigated the possibility of using these lectins as templates to select peptide mimotopes of tumor-associated carbohydrate Ags as immunogens to generate cross-reactive Abs capable of mediating apoptosis of tumor cells. In this study, we show that immunization with a mimotope selected based on its reactivity with Griffonia simplicifolia lectin I and wheat germ agglutinin induced serum IgM Abs in mice that mediated the apoptosis of murine 4T1 and human MCF7 cell lines in vitro, paralleling the apoptotic activity of the lectins. Vaccine-induced anti-carbohydrate Abs reduced the outgrowth of micrometastases in the 4T1 spontaneous tumor model, significantly increasing survival time of tumor-bearing animals. This finding parallels suggestions that carbohydrate-reactive IgM with apoptotic activity may have merit in the adjuvant setting if the right carbohydrate-associated targets are identified.

Po-topic IV-01: CU-ATSM an agent for hypoxia imaging and radiotherapy

Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) is in a class of copper bis(thiosemicarbazones) that we have evaluated in vitro and display uptake that is either nonhypoxia selective (eg, Cu-PTSM) to hypoxia selective. In vivo, Cu-ATSM is rapidly retained in hypoxic tumors and myocardium but diffuses out of normoxic tissue. In experimental tumor models the selective uptake of Cu-ATSM was seen to be pO2 dependent and a direct correlation between tissue uptake of Cu-ATSM and decreased tumor oxygenation was observed. In studies using the Langendorff isolated perfused rat heart model, in which oxygen concentration can be controlled, and in canine models of ischemic myocardium, we have shown that specific retention of Cu-ATSM is due to oxygen depletion. In a study of cervical cancer in humans we have shown that Cu-60-ATSM-PET is an excellent method for assessing tumor hypoxia in patients with cervical cancer. We have shown that the results of Cu-60-ATSM-PET correlate well with patient outcome. In radiotherapy studies, the systemic administration of Cu-64-ATSM has been shown to significantly increase the survival time of hamsters bearing human GW39 colon cancer tumors. Radiotherapy experiments were performed in animals bearing either 7-day (0.5–1.0 g) or 15-day (1.5–2.0 g) old tumors. Studies compared animals treated with escalating doses of Cu-64-ATSM that significantly increased the survival time of tumor-bearing animals. The highest dose, 10 mCi Cu-64-ATSM, increased survival to 135 days in 50% of animals bearing 7-day-old tumors, 6-fold longer than control animals’ survival (20 days), with only transient leucopenia and thrombocytopenia but no overt toxicity. High-resolution MRI and PET using a therapeutic administration of 10 mCi were used to monitor tumor volume and morphology and to accurately assess tumor dosimetry, giving a tumor dose of 81 ± 7.5 rad/mCi. We also investigated whether the intratumoral (i.t.) delivery of Cu-64-ATSM into the GW39 tumor resulted in an increased efficacy compared with an i.v. administration. We further investigated whether ATSM labeled with the shorter-lived Cu-61 would result in tumor regression. Studies were performed by administering i.t. a single dose of either 10 mCi of Cu-64-ATSM (n = 9) or 15.7 mCi of Cu-61-ATSM (n = 10). These levels of radioactivity were determined by dosimetry calculations to deliver identical absorbed doses to the GW39 tumor. MicroPET imaging (n = 2) following Cu-64-ATSM injection determined that the i.t. mode of delivery resulted in a significant difference in biodistribution compared with systemic delivery.

Combined CXC chemokine and interleukin-12 gene transfer enhances antitumor immunity.

It has been shown that intratumor administration of an adenovirus vector expressing IL-12 produces a potent T cell-mediated response that leads to significant tumor regression in a murine breast cancer model. IP-10 and MIG are CXC chemokines that recruit mononuclear cells in vivo. In addition to their chemotactic roles, IP-10 and MIG inhibit angiogenesis. We tested whether the addition of IP-10 or MIG may both enhance the antitumor immune response of IL-12 through T cell recruitment and inhibit tumor growth through angiostasis. Adenovirus vectors expressing IP-10 or MIG and/or IL-12 were administered intratumorally in a murine model of mammary adenocarcinoma and fibrosarcoma. Administration of IP-10 or MIG in combination with IL-12 resulted in considerable tumor regression and increased survival time of tumor-bearing animals as compared with IP-10, MIG, IL-12 alone or control-treated animals, with the IP-10 IL-12 combination being most effective. These results suggest augmenting the antitumor immune response and inhibiting tumor angiogenesis with adenoviral vectors expressing IP-10 in combination with IL-12 is a novel way to enhance tumor regression.

Copper-64-diacetyl-bis(N4-methylthiosemicarbazone): An agent for radiotherapy.

Systemic administration of hypoxia-selective (64)Cu-diacetyl-bis(N(4)-methylthiosemicarbazone) ((64)Cu-ATSM) has increased significantly the survival time of hamsters bearing human GW39 colon cancer tumors. Radiotherapy experiments were performed in animals bearing either 7-day-old (0.5-1.0 g) or 15-day-old (1.5-2.0 g) tumors. Studies compared animals treated with a single dose of 0, 4, 6, 7, 8, or 10 mCi of (64)Cu-ATSM (1 Ci = 37 GBq) with or without the vasodilator hydralazine. A multiple dose regimen of 3 x 4 mCi at 72-h intervals was studied also. Single doses of >6 mCi of (64)Cu-ATSM and the dose-fractionation protocol significantly increased the survival time of the hamsters compared with controls. The highest dose, 10 mCi of (64)Cu-ATSM, increased survival to 135 days in 50% of animals bearing 7-day-old tumors, 6-fold longer than control animals' survival (20 days), with only transient leucopenia and thrombocytopenia but no overt toxicity. Human absorbed doses were calculated from hamster biodistribution; the dose-critical organs were the lower large intestine (1.43 +/- 0.19 rad/mCi) and upper large intestine (1.20 +/- 0.38 rad/mCi). High-resolution MRI and positron-emission tomography using a therapeutic administration of 10 mCi were used to monitor tumor volume and morphology and to assess tumor dosimetry accurately, giving a tumor dose of 81 +/- 7.5 rad/mCi. (64)Cu-ATSM has increased the survival time of tumor-bearing animals significantly with no acute toxicity and thus is a promising agent for radiotherapy.

Glucans as immunological adjuvants.

β-1,3-Linked glucopyranose (β-glucan), a major structural component of yeast, fungi, and algae [1], has a wide range of biological activities. Systemic administration of β-glucan (1) provides nonspecific resistance in experimental animals against a variety of pathogenic challenges [2–7]; (2) prolongs the survival time of tumor-bearing animals [8,9]; (3) enhances bone marrow recovery and survival of lethally irradiated mice [10]; (4) promotes wound healing when applied topically [11,12]; and (5) displays an adjuvant effect when coadministered with either bacterial, fungal, protozoan, or viral agents[13–18].

Cell kinetic studies of the effect of a combined therapy with 1-beta D-arabinofuranosylcytosine (Ara-C) and X-irradiation on the L1210 ascites tumour.

We studied the effect of combined therapy with X-ray and 1-beta-D-arabinofuranosylcytosine (Ara-C); firstly the effect of whole-body X-irradiation alone on the proliferation of the L1210 ascites tumour of the mouse was studied by autoradiographic and cytofluorometric (FCM) methods. The effect X-irradiation with 4 Gy was mainly a cytostatic one leading to an altered distribution of the cells throughout the cycle due to radiation induced mitotic delay. The cytocidal effect is negligible. As is known from previous studies (Fietkau, Friede & Maurer-Schultze, 1984) the effect of 200 mg/kg Ara-C consists of an inhibition of DNA synthesis and of killing a considerable portion of the L 1210 cells, predominantly of S phase cells. With respect to the importance for potential therapeutic regimens, the influence of the sequence and the time interval between the two therapeutic steps on the survival of tumour-bearing mice was studied. Most combination therapies significantly increase the survival of tumour-bearing mice compared to the single therapeutic steps; however, no significant differences between the various combined therapies were found. Whole-body X-irradiation with 4 Gy followed by the application of 200 mg/kg Ara-C 10 hr later resulted in the greatest increase of the mean survival time of tumour-bearing animals, from 13.2 to 17.4 days. It was shown that apart from the cytocidal effect on S-phase cells, Ara-C also kills cells sublethally damaged by a preceding X-irradiation.

Combined cyclotron fast-neutron and BCNU therapy in a rat brain-tumor model.

The combination of cyclotron fast-neutron radiotherapy with BCNU chemotherapy was compared to 137Cs gamma photon radiotherapy combined with BCNU in the 36B-10, F-344 rat-transplanted glioma model. Radiation and drug treatments were administered 7 to 8 days after intracerebral tumor implantation. Increase in animal survival time was used as the measure of the effectiveness of various treatment schedules. Single-dose neutron or gamma radiotherapy was tested on Day 7 over the ranges 0 to 900 rads and 0 to 2000 rads, respectively. This therapy produced increases in mean survival times up to 70% at the highest radiation doses. When BCNU (10 mg/kg body weight) was administered intravenously on Day 8, 1 day following radiotherapy, mean survival times were increased by an additional 35% to 50%, irrespective of the dose or type of irradiation. In contrast, by using the same radiation and drug doses but scheduling combined therapy trials so that BCNU was administered 1 hour before either neutron or gamma irradiation on Day 7, there was enhancement of the radiation effect by BCNU. Under these conditions, the maximum enhancement of the mean survival time was 70% to 75% in neutron-treated animals and 120% to 150% in gamma-treated animals. Treatment with BCNU 1 hour before or 1 day after neutron irradiation proved to be no more effective in proving the survival time of tumor-bearing animals than the drug similarly combined with conventional gamma irradiation.

Blood-brain barrier and chemotherapy of experimental brain tumors (author's transl)

Using an experimental model of meningeal carcinomatosis in rats, studies of how the blood-CSF barrier was affected by tumor growth in the subarachnoid space were conducted. The state of the blood-CSF barrier was estimated by drug delivery to the tumor. Cyclophosphamide which crosses the blood-brain barrier poorly and 1-(4-amino-2-methyl-5-pyrimidinyl)-methy 1-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) which crosses it easily had an equivalent cytostatic effect on the subcutaneously transplanted Walker 256 carcinosarcoma in SD rats at a dose of 30 mg/kg and 15 mg/kg, respectively. SD rats inoculated intracisternally with 1×104 Walker 256 carcinosarcoma cells were treated by either a single i. v. dose of cyclophosphamide 30 mg/kg or ACNU 15 mg/kg at 1, 2, 4 or 5 days after tumor inoculation. Effects of these two types of agents were compared by the survival time of animals. At 1 day after tumor inoculation, intravenously administered cyclophosphamide failed to prevent tumor growth in the subarachnoid space and survival time of tumor-bearing animals was prolonged only 10 to 14% compared to control. On the other hand, ACNU was effective and produced a maximum increased survival time of 180%. At 2 days after inoculation both cyclophosphamide and ACNU were effective and increased median survival time by 109% and 127%, respectively. At 4 days after inoculation, cyclophosphamide increased survival time 90% and ACNU 240%. At 5 days, cyclophosphamide increased survival time 52% and ACNU 74%. The results indicated that the subarachnoid tumor growth in its early stage was protected from the water-soluble chemotherapeutic agent by the intact blood-CSF barrier. In the advanced stage of tumor growth, the barrier was mostly circumvented, however there were still some areas where infiltrating neoplastic cells were protected by the intact barrier. These findings suggest that systemic chemotherapy of metastatic tumors of the central nervous system should include an agent which crosses the blood-brain (CSF) barrier, although the first choice is an agent to which the original tumor is most sensitive.