Drug or radiation changes to the host which could affect the outcome of combined modality therapy

Induction of cisplatinum sensitivity without alteration in radiation sensitivity by fractionated radiation treatment of a human laryngeal squamous cell carcinoma cell line

PURPOSE

To determine if fractionated radiation treatment can alter cisplatinum sensitivity of a human laryngeal squamous carcinoma cell line.

METHODS AND MATERIALS

Human squamous carcinoma cells, both previously untreated, as well as survivors of fractionated radiation therapy, were tested in vitro for their sensitivity to gamma radiation and cisplatinum. Fractionated gamma radiation was delivered in 14 or 10 daily fractions of 2 Gy. The cell line, cSCC-20, was derived from an untreated primary human laryngeal carcinoma.

RESULTS

The human laryngeal squamous cell carcinoma cell line, cSCC-20, was demonstrated to have heterogeneous subpopulations with respect to cisplatinum sensitivity. No variation in radiation sensitivity was seen among subpopulations of varying cisplatinum sensitivity. The cells were relatively radioresistant (Do = 2.5 Gy). Fractionated radiation treatments of the parent cell line (14 fractions, 14 days, 2 Gy/fraction) or a cisplatinum sensitive subline (10 fractions, 12 days, 2 Gy/fraction) induced cisplatinum sensitivity (factor of 1.3 to 1.4) in the surviving cells.

CONCLUSION

Fractionated radiation treatment of human squamous carcinoma cells in vitro induced sensitivity to cisplatinum without concomitant alteration in radiation sensitivity.

Treatment of a human renal cell carcinoma in nude mice with recombinant human tumor necrosis factor alpha and etoposide

The effect of treating a human renal cell adenocarcinoma xenografted into Balb/c-nu/nu (nude) mice with recombinant human tumor necrosis factor alpha (TNF alpha) and the cytostatic agent etoposide (ETP) as monotherapy or combination has been studied. Antitumor effects were evaluated by determining growth of the tumor implants by external caliper measurements and tumor cell proliferation by determining the labelling index (LI) after pulse labelling with 3H-thymidine. The toxicity of the treatment with TNF alpha and/or ETP was also studied by measuring the animal weight. Monotherapy with TNF alpha had no effect on tumor growth or proliferation. Treatment with ETP as a single agent, TNF alpha plus ETP applied concurrently and TNF alpha plus ETP two days later led to a slight inhibition of tumor growth and also to a slight decrease of the LI. In contrast to a monotherapy with TNF alpha, all therapeutic modalities containing ETP showed an increased toxic effect on the animals represented by a distinct weight loss. This suggests that the minute efficacy of the treatment observed could well be due solely to its toxicity. In contrast to two other studies, no additive or synergistic effect of the antineoplastic activity of TNF alpha and/or ETP was found. The intertumoral variation of human renal cell carcinomas could be one reason for the different results with this therapeutic regimen.

Renal damage in mice after sequential cisplatin and irradiation: the influence of prior irradiation on platinum elimination

Doses of 4-6 mg kg-1 c-DDP given 6 months before renal irradiation caused only a modest increase in functional radiation damage (DEF 1.1). These effects could be explained by additive toxicities and the damage was much less than when c-DDP was given 3-6 months after irradiation. Pharmacokinetic studies did not demonstrate any decrease in the rate of platinum elimination after previous low-dose renal irradiation.

Hepatic function and drug pharmacokinetics after total body irradiation plus bone marrow transplant

Radiation nephritis is the principle late toxicity seen after total body irradiation in barrier-maintained rats when hematologic toxicity is prevented by bone marrow transplantation. Renal dysfunction is observed for single doses as low as 7.5 Gy. Hepatic blood flow, as measured by indocyanine green clearance, is decreased after 8.5-9.5 Gy single-dose total body irradiation. Serum albumin levels are decreased after 9.5 Gy single-dose total body irradiation. Hypoalbuminemia is a symptom of hepatic damage, but can also be caused by renal damage or edema. No decrease in total serum protein is observed, indicating that proteinuria resulting from renal damage is not the cause of hypoalbuminemia. No edema and some dehydration are observed. These data indicate that hepatic damage as well as renal damage may be occurring after total body irradiation plus bone marrow transplantation. Animals given total body irradiation plus bone marrow transplantation show decreased tolerance to a wide variety of immunosuppressive and cytotoxic drugs, even when these drugs are given months after total body irradiation. Altered drug clearance after total body irradiation plus bone marrow transplantation is observed for cis-platinum, vincristine, and adriamycin. The increase in cis-platinum toxicity after total body irradiation plus bone marrow transplantation is caused by decreased renal drug clearance. The decrease in vincristine tolerance and the alterations in adriamycin and vincristine pharmacokinetics are caused by altered drug distribution after total body irradiation plus bone marrow transplantation. These results indicate that bone marrow transplant survivors may show altered clearance of, and decreased tolerance to, a wide variety of drugs that are used after bone marrow transplantation.

The uptake of 3H-vincristine by a mouse carcinoma during a course of fractionated radiotherapy

The variations in uptake of 3H-vincristine sulphate, given as a bolus i.v. injection, by a transplantable murine tumour during a realistic course of fractionated daily gamma-radiation of 25 x 2.0 Gy have been investigated. Maximum levels of 3H in the tumours are found when the tracer is injected 4h after irradiation and the tumours are dissected out 1 h after injection. During the course of daily irradiation the pattern of uptake varies considerably but reproducibly. There are peaks of uptake after 7, 13 and 22 fractions of 2.0 Gy when the amount of 3H in the tumours is as much as three times that found in non-irradiated tumours. After 17-18 fractions, however, the tumour content of 3H is lower than that of non-irradiated tumours. The wave-like pattern of uptake could be due either to capillary occlusion brought about by radiation induced cellular swelling and oedema followed by re-opening of the capillaries during periods of decreased cellularity, or to some mechanism of recovery from radiation damage during the week-end rest period.

Thermochemotherapy in vivo of a C3H mouse mammary carcinoma: single fraction heat and drug treatment

The interaction between water bath hyperthermia (43.5 degrees C) and six cancer chemotherapeutic agents in vivo was studied in a transplantable C3H mouse mammary carcinoma grown s.c. in the feet of C3D2F1/Bom mice. Due to differences in tumour regrowth rate between treatment groups, both tumour growth time (TGT) and specific growth delay (SGD) were used as effect parameters. The largest tumour response was observed when the drug was given 15 min prior to heat--this timing was used for dose-effect experiments. Enhancement ratios were the ratios of slopes of dose-effect curves subjected to linear regression analysis. The drug enhancement ratio (DER) was not significantly larger than 1.0 for LD 1% of adriamycin, 5-fluorouracil, methotrexate and vincristine. For cyclophosphamide (CTX) and mitomycin C (MMC) both DER and TER (thermal enhancement ratio) were significantly larger than 1.0. The TGT ratios (SGD ratios in parentheses) were: DER (LD 1%): CTX 1.4 +/- 0.1 (2.1 +/- 0.1), MMC 1.3 +/- 0.1 (1.4 +/- 0.1); TER (43.5 degrees C 30 min): CTX 1.6 +/- 0.1 (2.7 +/- 0.2), MMC 2.8 +/- 0.5 (3.3 +/- 0.7). The data support the choice of CTX and MMC in preference to the other drugs investigated for clinical thermochemotherapy studies.

Applicability of animal tumor data to cancer therapy in humans

The problem of applying experimental tumor studies to clinical cancer therapy is a complex one. The radiotherapy literature contains many examples of premature efforts to apply laboratory observations to the clinic, and many examples of failures to adequately consider animal tumor observations in the design of clinical studies. This review covers three areas: tumor hypoxia, where clinical trials based on animal tumor data have been conducted with radiosensitizers, hyperbaric oxygen, and systemic oxygen carriers; dose fractionation, where current trials of hyperfractionation are based in part on animal tumor studies; and chemo-radiotherapy, where clinical trials are only beginning to exploit concepts developed in animal tumor systems. The use of animal tumor systems extends past the screening of new agents. Animal tumor models can be used in biological, physiological, and pharmacological studies to elucidate the biological factors influencing the efficacy of therapeutic agents. Tumor studies can be combined with studies of normal tissues to predict the toxicities to be anticipated in clinical trials, and to assess the potential for therapeutic gain. Animal studies can also provide data which are useful in designing optimal clinical trials of new agents and maximizing the potential for successful clinical application of new approaches. In general, it is not possible to apply specific laboratory data directly to man. To translate, rather than transpose, information from the laboratory to the clinic, the model studies must be directed at evaluating principles, rather than merely quantifying results. Only through studies of mechanisms, by designing experiments to test or refute a hypothesis, will it be possible to apply model studies to man.

Chronic effects of fractionated renal irradiation on the pharmacokinetics of intravenous methotrexate

the chronic effects of renal irradiation on the pharmacology of methotrexate was studied in a rat model. Unanesthetized rats received 2 doses of bilateral fractionated kidney irradiation (16.2 Gy or 19.8 Gy in 9 fractions). Alterations in renal function were first seen at 3 months in the 19.8 Gy group and 12 months in the 16.2 Gy groups. Life table analysis showed a shift in the survival curve of about 3 months between the 2 radiation doses. The pharmacokinetics of i.v. methotrexate showed an increase in the area under the plasma curve beginning at 9 months in the 19.8 Gy group and at 15 months in the 16.2 Gy group. The volume of distribution of methotrexate was smaller in the irradiated rats than in unirradiated controls. Multiple linear regression models showed significant correlations between parameters of methotrexate clearance and certain renal function tests. Nevertheless, no set of renal function tests consistently predicted alteration in methotrexate clearance in the 2 radiation groups. Furthermore, time after irradiation remained a highly significant variable indicating that renal irradiation causes time dependent change in methotrexate pharmacokinetics that can not be accounted for by the usual tests of renal function.

Experimental studies on interactions of radiation and cancer chemotherapeutic drugs in normal tissues and a solid tumour

The interactions of radiation and seven cancer chemotherapeutic drugs have been investigated in four normal tissues (intestinal crypts, skin, haemopoietic tissue and lung) and in a solid C3H mouse mammary carcinoma in vivo. All experiments were carried out with male C3D2F1 mice. The investigated drugs were adriamycin (ADM), bleomycin (BLM), cyclophosphamide (CTX), 5-fluorouracil (5-FU), methotrexate (MTX), mitomycin C (MM-C) and cis-diamminedichloroplatinum(II) (cis-DDP). Single drug doses were given at different intervals before, simultaneously with and after single doses of radiation. The normal tissue reactions following drug-radiation combinations were found to be highly complex. The interactions varied both quantitatively and qualitatively from drug to drug and from tissue to tissue. The drugs enhanced the radiation response in most cases. However, signs of radioprotection was observed for CTX in skin and for MTX in haemopoietic tissue. The interval and the sequence of the two treatment modalities were of utmost importance for the normal tissue reactions. In general, the most serious interactions occurred when drugs were administered simultaneously with or a few hours before radiation. The radiation-modifying effect of the drugs deviated from this pattern in the haemopoietic tissue as the radiation response was most enhanced on drug administration 1-3 days after radiation. Enhancement of the radiation response was generally less pronounced in the tumour model than in the normal tissues. The combined drug-radiation effect was apparently less time-dependent in the tumour than in the normal tissues.

Renal irradiation and the pharmacology and toxicity of methotrexate and cisplatinum

We used a rat model to study the effects of renal irradiation on the pharmacology of methotrexate (MTX) and cisplatinum (cis-Pt). Unanesthetized rats were given bilateral kidney irradiation (20 Gy in 9 fractions). At 9 months after irradiation, 3% of the animals had died and survivors showed moderately impaired renal function. At 15 months, 30% of the animals had died and survivors showed severely impaired renal function. Some animals were given i.v. MTX 1 week to 15 months after irradiation. In irradiated rats, the area under the MTX plasma clearance curve equaled that of controls through 6 months, and was significantly above controls from 9 months on. Other animals were given i.p. cis-Pt 1 week to 9 months after irradiation. The acute toxicity of cis-Pt was the same in control and irradiated rats when cis-Pt was given immediately before or after irradiation. Beginning 3 months after irradiation there was a progressive increase in cis-Pt toxicity and a simultaneous decrease in urinary platinum excretion. Irradiated animals that survived cis-Pt treatment showed increased radiation nephritis; the greatest effect occurred when cis-Pt was given 3 months or more after irradiation. MTX and cis-Pt clearance decreased when renal dysfunction was first observed and changes in renal function preceded changes in drug clearance and toxicity.

Combined hyperthermia and cis-diamminedichloroplatinum in BD IX rats with transplanted BT4A tumours

Effects on tumours and toxicity of locally applied waterbath hyperthermia (44 degrees C, 60 min) and cis-diamminedichloroplatinum (cis-DDP) were investigated in BD IX rats with transplanted BT4A tumours on the hind foot. The effect of cis-DDP at doses of 2, 3 and 4 mg/kg measured as tumour growth time, defined as time to reach five times the tumour volume at treatment, increased in a drug dose-dependent manner by using hyperthermia. Moderate systemic hyperthermia at a mean of 41 degrees C during the second half of the treatment also increased the tumour regrowth delay of cis-DDP. Skin reactions after local hyperthermia did not increase in this cis-DDP dose range, but systemic toxicity of the drug was markedly enhanced by hyperthermia. At histological evaluation, hyperthermia at 44 degrees C resulted in marked vasodilatation, red blood cell pooling and haemolysis, with a seemingly almost complete central tumour perfusion shutdown lasting up to five days after treatment. The combination of cis-DDP and hyperthermia resulted in additional cell death especially at the tumour periphery and at depth near the tendon and muscle. This in vivo study confirms in vitro data indicating cis-DDP as a candidate for clinical trials combined with hyperthermia. As both the tumour and systemic side effects of cis-DDP are enhanced by hyperthermia, caution is advocated when applying high drug doses with systemic hyperthermia.

Interactions of radiation and cancer chemotherapeutic drugs in a C3H mouse mammary carcinoma

The interactions of radiation and adriamycin (ADM), bleomycin (BLM), cyclophosphamide (CTX), 5-fluorouracil (5-FU), methotrexate (MTX), mitomycin C (MM-C), or cis-diamminedichloroplatinum II (cis-DDP) were studied in a spontaneously arisen C3H mouse mammary carcinoma. The tumour response to drugs alone was evaluated by measuring the tumour to reach a volume 5 times that of the treatment day. CTX resulted in a marked tumour growth delay whereas the other drugs had a modest or uncertain effect. In the combined treatment experiments, drugs were administered as single doses either 15 min before or 4 hours after graded single doses of irradiation. The end point for each treatment was the radiation dose which on an average was required to achieve local tumour control in 50 per cent of the mice (TCD50). The dose effect factor (DEF) was 1.16 for ADM and 1.17 for CTX, the enhanced radiation response being independent of administration before or after irradiation. MM-C also decreased the TCD50 for radiation alone, but its effect was more marked 15 min before (DEF 1.32) than 4 hours after irradiation (DEF 1.18). BLM, 5-FU, MTX, and cis-DDP had no effect on the radiation response neither when administered 15 min before nor 4 hours after irradiation.

Response to chemotherapy of EMT6 spheroids as measured by growth delay and cell survival

Multicellular tumour spheroids of the EMT6 mouse tumour line have been grown in a static (i.e. non-spinner) culture system to a mean spheroid diameter of 250 mum. Samples of spheroids were then exposed for 1 h to graded concentrations of various cytotoxic drugs, and the response assayed by both growth delay and survival of clonogenic cells. For nitrogen mustard (HN2), melphalan, BCNU, CCNU and cis-platinum, a considerable recovery in measured cell survival was seen if correlation between growth delay and cell survival (measured at 24 h) was observed for these 5 agents. For adriamycin, actinomycin D and 5-fluorouracil, no increase in measured cell survival was seen for a 24h delay in assay, and these agents produced longer growth delays for a given level of cell kill.