Chronic intratumoral chemotherapy of a rat tumor with cisplatin and fluorouracil

The effect of locally delivered cisplatin is dependent on an intact immune function in an experimental glioma model

Several chemotherapeutic drugs are now considered to exert anti-tumour effects, by inducing an immune-promoting inflammatory response. Cisplatin is a potent chemotherapeutic agent used in standard medulloblastoma but not glioblastoma protocols. There is no clear explanation for the differences in clinical efficacy of cisplatin between medulloblastomas and glioblastomas, despite the fact that cisplatin is effective in vitro against the latter. Systemic toxicity is often dose limiting but could tentatively be reduced by intratumoral administration. We found that intratumoral cisplatin can cure GL261 glioma-bearing C57BL/6 mice and this effect was abolished in GL261-bearing NOD-scid IL2rγnull (NSG) mice. Contrary to previous results with intratumoral temozolomide cisplatin had no additive or synergistic effect with whole cell either GL261 wild-type or GM-CSF-transfected GL261 cells whole cell vaccine-based immunotherapy. While whole tumour cell immunizations increased CD8+ T-cells and decreased F4/80+ macrophages intratumorally, cisplatin had no effect on these cell populations. Taken together, our results demonstrate that intratumoral cisplatin treatment was effective with a narrow therapeutic window and may be an efficient approach for glioma or other brain tumour treatment.

Efficacy of intracerebral delivery of cisplatin in combination with photon irradiation for treatment of brain tumors

We have evaluated the efficacy of intracerebral (i.c.) convection-enhanced delivery (CED) of cisplatin in combination with photon irradiation for the treatment of F98 glioma-bearing rats. One thousand glioma cells were stereotactically implanted into the brains of Fischer rats and 13 days later cisplatin (6 microg/20 microl) was administered i.c. by CED at a flow rate of 0.5 microl/min. On the following day the animals were irradiated with a single 15 Gy dose of X-rays, administered by a linear accelerator (LINAC) or 78.8 keV synchrotron X-rays at the European Synchrotron Radiation Facility (ESRF). Untreated controls had a mean survival time (MST) + or - standard error of 24 + or - 1 days compared to >59 + or - 13 days for rats that received cisplatin alone with 13% of the latter surviving >200 days. Rats that received cisplatin in combination with either 6 MV (LINAC) or 78.8 keV (synchrotron) X-rays had almost identical MSTs of >75 + or - 18 and >74 + or - 19 days, respectively with 17 and 18% long-term survivors. Microscopic examination of the brains of long-term surviving rats revealed an absence of viable tumor cells and cystic areas at the presumptive site of the tumor. Our data demonstrate that i.c. CED of cisplatin in combination with external X-irradiation significantly enhanced the survival of F98 glioma-bearing rats. This was independent of the X-ray beam energy and probably was not due to the production of Auger electrons as we previously had postulated. Our data provide strong support for the approach of concomitantly administering platinum-based chemotherapy in combination with radiotherapy for the treatment of brain tumors. Since a conventional LINAC can be used as the radiation source, this should significantly broaden the clinical applicability of this approach compared to synchrotron radiotherapy, which could only be carried out at a very small number of specialized facilities.

Sustained release chemotherapeutic microspheres provide superior efficacy over systemic therapy and local bolus infusions

PURPOSE

The present studies evaluated the ability of injectable, biodegradable microspheres releasing carboplatin, doxorubicin, or 5-fluorouracil to suppress the growth of solid tumors implanted subcutaneously or intramuscularly.

METHODS

Seven to 10 days after implantation of MATB-III cells, rats received systemic chemotherapy, intratumoral bolus chemotherapy, or injections of chemotherapeutic microspheres into the tumor center or multiple sites along the outer perimeter of the tumor.

RESULTS

A single treatment with carboplatin, doxorubicin, or 5-fluorouracil microspheres along the perimeter of the tumors produced a significant, dose-related suppression in tumor growth, relative to injections directly into the tumor center. Moreover, five temporally-spaced microsphere treatments along the tumor perimeter (with either doxorubicin or 5-fluorouracil microspheres) completely eradicated 100% of the subcutaneous tumors and 40-53% of the intramuscular tumors. Polypharmacy, accomplished by blending doxorubicin- and 5-fluorouracil-loaded microspheres and injecting them into the tumors was even more efficacious than sustained delivery of either drug alone. Comparable doses of systemic chemotherapy or intratumoral bolus chemotherapy were ineffective.

CONCLUSIONS

Injectable microspheres might be ideal for local, sustained delivery of chemotherapeutic agents to solid tumors. However, attention must be paid to the placement of the microspheres, for injections around the tumor perimeter may be required for efficacy.

Interstitial chemotherapy of experimental brain tumors: comparison of intratumoral injection versus polymeric controlled release

Interstitial chemotherapy with controlled release polymers is a clinical adjunct in the management of malignant gliomas. The need for polymer to release the chemotherapeutic drug rather than simply injecting the drug into the tumor warrants further investigation. Therefore, we compared the effects of direct intralesional injection of carmustine (BCNU) and 4-hydroperoxycyclophosphamide (4HC) into the rat brain tumor bed with those from the same agents delivered via controlled release polymers implanted intracranially. Treatment was initiated on the fifth day after intracranial implantation of 9L gliosarcoma into male rats; two doses of each drug were injected intratumorally, representing either the amount of drug typically released in vivo from polymer during the first 24 h, or the maximal drug loaded on each polymer. Control rats were treated with empty polymers. We found that the median lifespan was extended in the groups of rats treated with intratumoral injection of BCNU (23% and 36% for 1 mg and 2 mg doses), and 271% with BCNU-impregnated polymer. Similar results were found with intratumoral 4HC (21% and 36% for 0.1 mg and 2 mg injection doses), and 121% with 4HC-impregnated polymer. Overall survival after intraneoplastic injections, however, was not statistically significantly different from that of control rats (p > 0.05). Furthermore, improvement in survival was not consistent, and some animals subjected to 4HC injection died early in the course of treatment. Polymeric treatment resulted in statistically significant prolongation of survival, compared to control rats (p < 0.001 for both BCNU and 4HC). We concluded that direct intralesional injection of BCNU and 4HC is less effective than controlled release via polymers for the treatment of 9L gliosarcoma in the rat model.

Convection-enhanced delivery of macromolecules in the brain

For many compounds (neurotrophic factors, antibodies, growth factors, genetic vectors, enzymes) slow diffusion in the brain severely limits drug distribution and effect after direct drug administration into brain parenchyma. We investigated convection as a means to enhance the distribution of the large and small molecules 111In-labeled transferrin (111In-Tf; M(r), 80,000) and [14C]sucrose (M(r), 359) over centimeter distances by maintaining a pressure gradient during interstitial infusion into white matter to generate bulk flow through the brain interstitium. The volume of distribution (Vd) containing > or = 1% concentration of infusion solution increased linearly with the infusion volume (Vi) for 111In-Tf(Vd/Vi, 6:1) and [14C]sucrose (Vd/Vi, 13:1). Twenty-four hours after infusion, the distribution of 111In-Tf was increased and more homogeneous, and penetration into gray matter had occurred. By using convection to supplement simple diffusion, enhanced distribution of large and small molecules can be obtained in the brain while achieving drug concentrations orders of magnitude greater than systemic levels.

Effects of intralesional injection of cisplatin dissolved in urografin and lipiodol on Ehrlich ascites tumor and normal tissues of CD-1 mice

The response of Ehrlich ascites tumor and the effect on normal tissues (kidney and small intestine) of CD-1 mice were evaluated after intralesional (i.l.) injection of cisplatin dissolved in urografin and lipiodol, which is henceforth termed CUL suspension. The results obtained were compared with the effects of i.p. and i.l. injections of cisplatin dissolved in sterile distilled water. Each of these treatment modalities involves the injection of 10 mg/kg cisplatin. The tumor response was evaluated by tumor growth-delay studies as well as by determining the percentage of cells in the S phase. Toxicity studies were accomplished by evaluation of the change in the body weight of mice and also by S-phase studies. S-phase fraction analyses were done with the use of the Cell Proliferation Kit. This commercial kit was used to measure bromodeoxyuridine (BrdU), a thymidine analogue that is incorporated into cells synthesizing DNA. Tumor, kidney, and small-intestine platinum concentrations were determined by measurement with a flameless atomic absorption spectrophotometer. The results of the tumor growth-delay studies showed that i.p. injection, with water being the drug carrier, produced the weakest antitumor effect, whereas i.l. injection of cisplatin, with lipiodol being the drug carrier, evoked the most enhanced effect. This finding was substantiated by BrdU-uptake analysis of tumor cells, wherein i.p. injections yielded the highest S-phase fraction and CUL treatment gave the lowest. Toxicity studies showed that a very significant decrease in body weight occurred in mice receiving i.p. treatment. No significant decrease in body weight was noted after i.l. treatment. BrdU analysis revealed that DNA synthesis in kidney cells and crypt cells of the small intestine was depressed after i.p. treatment. On the other hand, no significant effect was observed in the kidney or small intestine of CUL-treated mice. A correlation between the effects of the various treatment modalities (on tumors, kidney, and small intestine) and the retention of cisplatin was found.