The optimal combination of hyperthermia and carbogen breathing to increase tumor oxygenation and radiation response

PURPOSE

To determine the most effective combination of carbogen breathing with mild temperature hyperthermia (MTH) to increase the oxygenation and radiation response in murine tumors.

METHODS AND MATERIALS

MTH at 41.5 degrees C for 60 min was applied by immersion of the tumor in a precisely controlled water bath. The tumor pO2 was measured with a polarographic microelectrode. The radiation response of the tumor was determined using the in vivo/in vitro assay for surviving tumor cells.

RESULTS

In the FSaII fibrosarcoma the median pO2 increased from a control value of 6.5 +/- 0.5 mm Hg to 16.6 +/- 1.1 mm Hg immediately after MTH and was 10.9 +/- 1.3 mm Hg 24 h later. Carbogen breathing for 5 min increased the FSaII pO2 to 19.9 +/- 2.1 mm Hg. Carbogen breathing for 5 min beginning immediately after MTH increased the median pO2 more than 5 times to 35.4 +/- 3.8 mm Hg. This combined treatment also substantially increased the response of the tumors to a radiation exposure of 20 Gy. In another tumor model, the SCK mammary carcinoma, MTH treatment increased the median pO2 from the control level of 4.4 +/- 0.2 mm Hg to 12.6 +/- 1.2 mm Hg, and it returned to 4.3 +/- 0.3 mm Hg 24 h later. Carbogen breathing for 5 min increased the SCK tumor pO2 to 17.1 +/- 1.4 mm Hg. The median SCK pO2 was increased about 7 times to 31.2 +/- 4.2 mm Hg when MTH was followed immediately with carbogen breathing for 5 min. The radiation response was also markedly increased by this combination. When the animals breathed carbogen for 15 or 30 min, the pO2 and radiosensitivity in both tumor types either remained the same or was lower than that after 5 min of breathing. In addition, both FSaII and SCK tumors were radiosensitized 24 h after MTH treatment alone or with 5 min of carbogen breathing.

CONCLUSIONS

A shorter carbogen breathing time immediately after MTH causes the most tumor radiosensitization. The results of this study also demonstrate that MTH increases radiosensitivity with and without carbogen breathing up to 24 h after the mild hyperthermia treatment.

Are hypoxic cells critical for the outcome of fractionated radiotherapy in a slow-growing mouse tumor?

PURPOSE

To investigate the significance of hypoxic cells, reoxygenation and repopulation for the outcome of fractionated radiotherapy of a slow-growing subline of a murine fibrosarcoma and to compare the results with those previously obtained from the original fast-growing tumor.

MATERIALS AND METHODS

A slow-growing subline, 457-O, was obtained among the tumors that recurred after a single irradiation to the third generation isotransplants of a mouse fibrosarcoma, FSa-II. The single cell suspensions were transplanted into the mouse foot and when the tumors reached an average diameter of 4 mm, they were subjected to one to 20 equal daily y-ray doses given in air (A) or under hypoxic conditions (H). The TCD50 (50% tumor control radiation dose) was calculated according to the tumor control frequency within 180 days. The linear-quadratic plus time model was fitted to these data by logistic regression analysis.

RESULTS

The volume doubling time of the 457-O tumors was approximately 2.2 times slower than that of the original FSa-II tumors. The TCD50(H) (single dose) was 52.3 Gy and increased with an increasing number of fractions to a TCD50(H) (20 doses) of 90.8 Gy. This increase of 38.5 Gy was much smaller than that of 149 Gy for the original FSa-II. The TCD50(A) (single dose) and TCD50(A) (20 doses) were 41.3 and 50.6 Gy, respectively. This small difference of 9.3 Gy contrasted with a significant increase of 52.9 Gy for the FSa-II.

DISCUSSION

These results suggested no repopulation of 457-O tumor clonogens during the course of up to 20 daily doses, while the original FSa-II tumor cells repopulated substantially. Hypoxic clonogens in the slow-growing tumor reoxygenated but some fractions remained critical.

CONCLUSION

The present data together with those obtained from the fast-growing FSa-II suggested that hypoxic clonogens were critical for the outcome of fractionated radiotherapy. Repopulation was insignificant in this slow-growing tumor during five to 20 daily doses.

Dental anomalies caused by oncological treatment: case report

In infancy, the oncological treatment is at times chemoradiotherapy. This treatment may cause dental development anomalies that can affect the form and structure of the tooth. A case report with this type of dental damage is presented.

Radiosensitization of mouse sarcoma cells by fludarabine (F-ara-A) or gemcitabine (dFdC), two nucleoside analogues, is not mediated by an increased induction or a repair inhibition of DNA double-strand breaks as measured by pulsed-field gel electrophoresis

PURPOSE

To investigate the effect of fludarabine (F-ara-A) and gemcitabine (dFdC), two radiosensitizing nucleoside analogues, on the induction and repair of DNA dsb after ionizing radiation.

MATERIALS AND METHODS

Radiosensitization of mouse sarcoma SA-NH and FSA cells was studied using a clonogenic assay. Cell survival curves were fitted with the linear-quadratic model. DNA dsbs were detected by pulsed-field gel electrophoresis under neutral conditions.

RESULTS

F-ara-A (100 micromol dm(-3) for 1 h prior to irradiation) induced a substantial radiosensitization in SA-NH cells with a dose modification factor of 2.0 for a surviving fraction of 0.5. In a FSA mouse sarcoma cell line, dFdC (5 micromol dm(-3) for 3 h prior to irradiation) induced a modest radiosensitization with a DMF of 1.2 for a surviving fraction of 0.5. Under similar experimental conditions, neither F-ara-A nor dFdC altered the yield of radiation-induced DNA dsbs in the dose range of 0-40 Gy. After a single dose of 25 Gy (SA-NH cells) or 40 Gy (FSA cells), neither the kinetics of repair nor the amount of residual damage was affected by F-ara-A or dFdC.

CONCLUSIONS

For experimental conditions under which radiosensitization was observed, neither the induction nor the repair of DNA dsbs after ionizing radiation were affected by F-ara-A or dFdC.

Involvement of nitric oxide during phthalocyanine (Pc4) photodynamic therapy-mediated apoptosis

Photodynamic therapy (PDT), a new treatment modality, uses a combination of photosensitizing agent and visible light for the therapy of many solid malignancies. The hallmark of PDT is intracellular oxidative stress mediated by reactive oxygen species, which, through a cascade of events, results in a cell kill that induces apoptosis in some cells. To better understand the mechanism of apoptosis, we hypothesized the role of nitric oxide (NO), which is considered to be involved in a variety of physiological and pathological processes, during PDT. The model photosensitizer we have been working with is a silicon-phthalocyanine compound termed Pc4. Here, we investigated the involvement of NO during Pc4 PDT in PDT of apoptosis-resistant radiation-induced fibrosarcoma (RIF-1) cells and in PDT of apoptosis-sensitive human epidermoid carcinoma (A431) cells. Pc4 PDT resulted in a rapid increase in nitrite production in A431 cells, starting as early as 15 s post-PDT, and showed a progressive increase up to 15 min post-PDT. This increase in nitrite production was observed in cell lysates as well as in the cell culture medium. RIF-1 cells did not show an increase in nitrite production in either the cell lysates or the culture medium. At this time, a majority of the cells were viable. The Western blot analysis also showed a rapid increase in the expression of the constitutive form of NO synthase as early as 15 s post-PDT when compared to that of the controls. This response showed a dose dependency up to 5 min after Pc4 PDT. This observation was confirmed by a [3H]L-citrulline assay, which also showed a similar pattern for constitutive NO-synthase activity. RIF-1 cells did not show any change in protein expression or enzyme activity after the same treatment. These data, for the first time, demonstrate the generation of NO during PDT and suggest that it may be involved in PDT-mediated apoptosis. This may have relevance in improving the therapeutic efficacy of PDT using pharmacological modulators of NO or NO synthase.

[Late results of radiotherapy of soft tissue sarcoma]

PURPOSE

To evaluate the effect of radiation therapy in the treatment of soft-tissue sarcomas.

MATERIALS AND METHODS

Between March 1970 and January 1990, 58 patients with soft-tissue sarcoma were referred for radiation therapy. The most frequent histologic diagnoses included fibrosarcoma (n = 15), neurofibrosarcoma (n = 5) and rhabdomyosarcoma (n = 5). Central tumor sites in the trunk (n = 31) were much more frequent than in the head and neck region (n = 14) or the extremities (n = 13). Thirty-nine of 58 primary tumors were bigger than 5 centimeters. Forty-five patients were irradiated after surgery, 5 patients prior to surgery; in 8 cases only radiation therapy was used. Radiation therapy was performed with Co-60 photons and an average total dose of 58 Gy, fractionated in single doses of 2 Gy. The treatment results were obtained by actual follow-up examinations.

RESULTS

Twenty-three of 58 patients survived at least 5 years (39.9%). Of 15 patients with R0 resection 11 were alive after 5 years (73.3%). Local tumor control was achieved in 34 of 58 patients (58.6%). Low 5-year-survival rates were associated with dedifferentiation of the primary tumor (three survivors in 10 patients with G3 tumor), tumor diameters over 5 cm (13 survivors of 39), R2 resection (3 survivors of 16) and tumor sites in the body trunk (11 survivors of 31).

CONCLUSIONS

(1) The best results of radiation therapy were achieved after R0 resection of the primary tumor. (2) Tumors in the trunk are prognostically worse because of bigger tumor diameters due to later diagnosis.

Radiation therapy and surgery for fibrosarcoma in 33 cats

Thirty-three cats with histologically confirmed fibrosarcomas were treated with radiation therapy followed by surgery. The median (95% confidence interval) disease free interval and overall survival were 398 (261,924) and 600 (lower limit 515) days, respectively. There were 19 treatment failures; 11 cats had only local recurrence, 4 cats developed metastatic disease, 3 cats had local recurrence followed by metastasis, and 1 cat developed simultaneous local and distant disease. Twelve cats are alive and disease free. Two cats died without evidence of treatment failure. The presence of tumor cells at the margin of resected tissue after radiation was the only variable which influenced treatment success. The median (95% confidence interval) disease free interval in 5 cats with tumor cells at the margin of the resected specimen was 112 (94,150) days versus 700 (lower limit 328) days for 26 cats with negative tumor margins, p < 0.0001. We did not identify a relationship between tumor volume, number of prior tumor excisions, concomitant use of chemotherapy or various descriptors of the radiation therapy technique and disease free interval.

Improvement of tumor oxygenation status by mild temperature hyperthermia alone or in combination with carbogen

The effects of mild temperature hyperthermia (MTH) on the oxygenation and radioresponse in rodent tumors were investigated. FSall tumors grown in the legs of C3H mice and R3230 AC tumors grown in the legs of Fischer rats were heated with a water bath and the partial pressure of oxygen (pO2) was determined using the microelectrode method. In FSall tumors, the pO2 measured immediately after heating at 41.5 degrees C for 1 hour was markedly higher than that in the control tumors, whereas heating at higher temperatures for 1 hour decreased the tumor oxygenation. In R3230 AC tumors, heating at 41.5 degrees C for 1 hour caused a moderate increase in the pO2 and heating at 42.5 degrees or 43.5 degrees C for 30 minutes markedly increased the pO2. However, heating at 42.5 degrees C or higher temperatures for 1 hour decreased the pO2 in the R3230 AC tumors. The improvement of oxygenation in FSall tumors by heating at 41.5 degrees C for 1 hour increased the radiation-induced cell death in these tumors. The combination of carbogen breathing with MTH was far more potent than carbogen breathing or MTH alone in increasing tumor oxygenation and potentiating the radiation effect in FSall tumors.

The effect of UCN-01 (7-hydroxystaurosporine), a potent inhibitor of protein kinase C, on fractionated radiotherapy or daily chemotherapy of a murine fibrosarcoma

PURPOSE

To investigate the effect of UCN-01 (7-hydroxystaurosporine), a potent and selective protein kinase C inhibitor, on fractionated irradiation or daily chemotherapy; cis-diamminedichloroplatinum(II) (cis-DDP) or 5-fluorouracil (5-FU) in vivo. Radiosensitivity and chemosensitivity given in combination with UCN-01 were further studied in vitro to analyze these in vivo results.

METHODS AND MATERIALS

For in vivo studies, single-cell suspension was prepared from fourth generation FSa-II tumors and transplanted subcutaneously into the leg of 8-10-week-old C3Hf/Sed mice. Treatments were initiated when tumors reached an average diameter of 4 mm. Tumor response was studied using tumor growth and growth delay time assays. UCN-01 was given continuously for 7 days using Alzet osmotic pump (4.0 microg/microl/h or approximately 3.2 mg/kg/day). A daily gamma-ray dose of 10 Gy each was given in air for 7 days. Cis-DDP (0.7 mg/kg/day) or 5-FU (20 mg/kg/day) was given by an i.p. injection for 7 days. For in vitro studies, an established FSa-II cell line was used and cell survival was studied by colony formation assay.

RESULTS

UCN-01 acted synergistically with fractionated irradiation, though it was slightly radioprotective in vitro and had no effect on SLD repair. The surviving fraction of the FSa-II cells treated with both UCN-01 and cis-DDP in vitro was lower than the calculated additive effect; however, the sensitizing effect of UCN-01 was not found when combined with either of the chemotherapeutic agents in vivo. Possible causes of synergism of combined UCN-01 and fractionated radiation may be that a continuous UCN-01 treatment inhibited clonogen repopulation during the course of fractionated irradiation and accumulated cells in the G2-M phase where cells are most sensitive to irradiation.

CONCLUSION

UCN-01 is a promising agent that may indirectly interact with fractionated irradiation in vivo but may not with chemotherapeutic agents.

Single dose radiocurability of four murine solid tumors and a predictive assay for the curability in situ

Correlations between radiocurability and kinetic parameters were investigated in four transplantable tumor types in WHT/Ht mice. The radiation dose to achieve 50% tumor control at 120 days after irradiation, i.e., TCD50/120, was 30 Gy for squamous cell carcinoma H, 32 Gy for squamous cell carcinoma NOS, 46 Gy for rhabdomyosarcoma KAS, and 63 Gy for fibrosarcoma YAS. The tumor cell kinetic parameters investigated were specific growth delay, volume doubling time, 125I-iododeoxyuridine (IUdR) uptake rate, and specific cell loss rate. The specific cell loss rate was defined as the ratio of cell loss rate in non-irradiated tumors to the rate in irradiated tumors, and was obtained by measuring the retention rate of radioactivity in the tumors. No correlations were found between specific growth delay, volume doubling time, 125I-IUdR uptake rate, and TCD50. However, the specific cell loss rate correlated with the TCD50. Therefore, the 125I-IUdR labeling method may be useful as an in situ predictive assay for tumor radiocurability.

Effects of IL-3 gene expression on tumor response to irradiation in vitro and in vivo

Expression of a murine interleukin 3 gene in murine fibrosarcoma cells (FSA-JmIL-3) did not alter their survival after in vitro irradiation. However, FSA-JmIL-3 tumors established in vivo were much more sensitive to irradiation than was the parental tumor. Following 25 Gy of irradiation, parental fibrosarcoma tumors regrew after a growth delay of 10 days, but FSA-JmIL-3 tumors continued to regress. Examination of the cellular composition of tumors following irradiation revealed that, instead of tumor cell repopulation, the FSA-JmIL-3 tumors became heavily infiltrated with lymphocytes, indicating that the effect of irradiation was to allow the IL-3-elicited cellular immune response to infiltrate the tumors and mediate rejection. This study indicates that combining gene immunotherapy approaches with radiotherapy might increase the effectiveness of both, and it seems logical to pursue such treatment options.

Sensitivity to radiation treatment and changes in metallothionein synthesis in a transplanted murine tumor

A protective role for metallothionein (MT) in cellular injury caused by ionizing radiation has been proposed. To elucidate the role of MT in the sensitivity of tumors to radiation, we examined the effectiveness of radiation treatment of tumors with altered synthesis of MT after injection of tumor-bearing mice with zinc and/or propargyl glycine (PPG). The mice were inoculated with Meth-A fibrosarcoma cells and the antitumor activity of X radiation was tested in mice with and without induced synthesis of MT. Exposure to X radiation decreased the tumor weight markedly. In mice pretreated with zinc to induce MT, the tumor weight did not change compared to the controls. However, injection of PPG, an inhibitor of cystathionase, decreased the zinc-induced MT synthesis in the tumors and also decreased the tumor weight after exposure to X radiation. These results suggest that in radiation therapy one of the factors involved in radiosensitivity may be the expression of MT in certain tumors.

Adjuvant therapy: the effects on microvascular lower extremity reconstruction

Adjuvant therapy and microsurgery have allowed advances in surgical extirpation of lower extremity neoplasms. This retrospective study was designed to evaluate the microvascular transfer for lower extremity reconstruction in patients receiving pre- or post-operative irradiation and chemotherapy alone and in combination. Over a 5-year period, 24 free tissue transfers were performed in 22 patients undergoing surgical resection with adjuvant therapy for lower extremity neoplasms. There were 13 male and 9 female patients with an average age of 51 years. The latissimus dorsi muscle was most commonly transferred (N = 15). Eighteen tumors received pre- and three received postoperative radiotherapy. Two tumors received a combination of radiotherapy and brachytherapy. Pre- and/or postoperative chemotherapy was used in 14 patients. Twelve of these patients had both chemo- and radiation therapy. A total of six complications occurred, with no flap loss. Complications were evenly distributed among adjuvant regimens. All patients who underwent attempted limb salvage were able to ambulate postoperatively, except for 1 patients who had local recurrence. In conclusion, adjuvant therapy did not increase the complication rate for free tissue transfer in the lower extremity. Adjuvant therapy did not require alterations in the free tissue transfer and, similarly, free tissue transfer did not alter adjuvant therapy. We believe that free tissue transfer in complicated wounds allows for better wound healing with adjuvant therapy rather than local or primary wound closure alone.

Induction thermochemotherapy increases therapeutic gain factor for the fractionated radiotherapy given to a mouse fibrosarcoma

PURPOSE

It has been shown that thermochemotherapy (TC) given prior to radiation reduces the number of clonogens, with a resultant decrease in the tumor control radiation dose. The purpose of this article was to investigate using an animal tumor model how this clonogen reduction affects subsequent fractionated radiotherapy, including repopulation of surviving clonogens, and whether the induction TC can increase the therapeutic gain factor (TGF).

METHODS AND MATERIALS

The single-cell suspensions prepared from the fourth-generation isotransplants of a spontaneous fibrosarcoma, FSa-II, were transplanted into the C3Hf/Sed mouse foot. TC was given by heating tumors at 41.5 degrees C for 30 min immediately after an intraperitoneal injection of cyclophosphamide (200 mg/kg) when tumors reached an average diameter of 4 mm. Fractionated radiotherapy (R) with equally graded daily doses was initiated 24 h after TC either in air (A) or under hypoxic conditions (H). The 50% tumor control dose (TCD50) and the radiation dose to induce a score 2.0 reaction (complete epilation with fibrosis) in one-half of irradiated animals, RD50(2.0), were obtained, and the TGF was calculated. Our previous results on the fractionated radiotherapy using the same tumor system served as controls.

RESULTS

The TCD50(A, single dose) and TCD50(H, single dose) following TC+R were 52.2 and 57.3 Gy, respectively, which were 14.0 and 20.4 Gy lower than those following radiation alone. The TCD50(A, TC+R) increased only slightly when the number of fractions was increased from one to 10 doses, and all TCD50s were significantly lower than the TCD50(A, R alone). Both TCD50(H, TC+R) and TCD50(H, R alone) increased consistently from a single dose to 20 doses, but all TCD50(H, TC+R) were significantly lower than the TCD50(H, R alone). Regarding the normal tissue reaction, the RD50 values both following TC+R and R alone increased consistently from a single dose to 20 daily doses. However, the RD50(TC+R) and RD50(R alone) for each corresponding number of fractions was not significantly different, resulting in the TGFs significantly > 1.0 for combined TC+R treatments, with the exception of 20 daily doses given in air.

CONCLUSION

The induction TC decreased the TCD50 values substantially without altering the RD50 for a late reaction, resulting in an significant increase in the TGF. These results encourage the use of TC as an induction treatment prior to fractionated radiotherapy.

Analysis of prognostic factors and patterns of failure in dogs with malignant oral tumors treated with megavoltage irradiation

OBJECTIVE

To determine quality and duration of progression-free survival (PFS) time in dogs with malignant oral tumors after definitive megavoltage irradiation, to analyze prognostic factors for PFS time and patterns of failure, and to analyze the influence of tumor recurrence and development of metastasis on survival.

DESIGN

Prospective clinical trial.

ANIMALS

105 dogs with squamous cell carcinoma, fibrosarcoma, or malignant melanoma of the oral cavity without evidence of metastasis.

PROCEDURE

Dogs were treated with 48 Gy over 4 weeks on an alternate-day schedule of 4 Gy/fraction. Multivariate analysis was done by use of Cox's regression model to determine significant prognostic factors and by use of a competing risk model to determine the differential effects of prognostic factors on type of, and time to, failure. In 8% of the dogs, severe acute radiation reactions in the final week of treatment resulted in treatment discontinuation. In 7.6% of the dogs, chronic radiation reactions, including bone necrosis and fistula formation, developed.

RESULTS

Prognostic factors that independently affected PFS time were histologic type and tumor T stage. Histologic type significantly influenced pattern of failure, but not time to failure, whereas clinical stage significantly influenced time to failure, but not type of failure.

CLINICAL IMPLICATIONS

Irradiation was a safe and effective treatment of malignant oral tumors. Because the local efficacy of radiation was influenced only by tumor size, early treatment of oral tumors should improve the prognosis. In dogs without tumor recurrence, systemic metastases, rather than regional metastases, limited long-term survival after radiation therapy.

31P magnetic resonance spectroscopy detection of response-predictive adenosine triphosphate decrease in irradiated radiation-induced fibrosarcoma-1 tumors

RATIONALE AND OBJECTIVES

In previous phosphorus-31 (31P) magnetic resonance (MR) spectroscopy studies of radiation-induced fibrosarcoma (RIF-1), tumor model single-dose x-ray irradiation was applied at subcurative doses. A more effective x-ray does was used in this study, allowing correlation of treatment efficacy with the early changes observed in the 31P MR spectra of RIF-1 tumors.

METHODS

Subcutaneous RIF-1 tumors of 60 mice were examined by 31P MR spectroscopy shortly before a single localized x-ray dose of 40 Gy and at eight times (2, 12, 24, 48, 72, 120, 168, and 216 hours) thereafter.

RESULTS

Early increases in the relative concentration of inorganic phosphate and decreases in adenosine triphosphate (ATP), most notably at 2 and 12 hours (each P < 0.00001), were observed that lasted up to 48 hours after irradiation. Phosphomonoester and tumor pH showed decreases that reversed even earlier. Reduction of ATP measured at 48 hours after irradiation was, however, correlated with percent tumor shrinkage observed during the subsequent weeks (r = -0.59; P < 0.00001).

CONCLUSIONS

Sustained loss of RIF-1 tumor ATP is predictive of treatment efficacy. Temporary depression of high-energy phosphate in favor of inorganic phosphate does not necessarily lead to cell death.

Enhancement of tumor antigen expression and inhibition of pulmonary metastasis of rat fibrosarcoma cells by local radiotherapy

Pulmonary metastasis formation after local radiotherapy against a rat fibrosarcoma was investigated. KMT-17 fibrosarcoma cells were transplanted into the hind leg in syngeneic WKA rats and two different doses (30Gy, 60Gy) of irradiation from a 60Co source were applied 5 days after transplantation. Pulmonary metastasis was inhibited by 30Gy irradiation rather than 60Gy irradiation, which was enough to almost completely cure the local tumors. This inhibitory effect of 30Gy irradiation was induced by the continued presence of irradiated tumors. As for pulmonary metastasis, the different effects of irradiation doses were not recognized when the tumor was removed surgically 1 day after irradiation, but when it was removed 4 days after 30Gy irradiation significantly inhibited metastasis. Expression of tumor-associated antigen (TAA), termed CE7 antigen, on the cell surface was enhanced effectively and continuously by 30Gy irradiation rather than by 60Gy. With this increase in CE7-expressing cells, the enhancement of anti-tumor immunity of spleen cells was observed in an in vitro 125I-IudR release assay and an in vivo tumor-neutralizing assay (Winn assay). The above results suggest that an appropriate dose of irradiation such as 30Gy, to a local tumor can efficiently enhance the TAA expression and that TAA-expressing cells may stimulate anti-tumor immunity, resulting in inhibition of pulmonary metastasis. This phenomenon may offer the possibility of resistance to micrometastasis through the induction of antitumor effector cells.

Mild temperature hyperthermia combined with carbogen breathing increases tumor partial pressure of oxygen (pO2) and radiosensitivity

The partial pressure of oxygen (pO2) of FSaII tumors grown in the leg of C3H mice significantly improved when the tumors were heated by immersing the tumor-bearing legs in a water bath at 41.5 degrees C for 60 min. The tumor pO2 also substantially increased when the tumor-bearing mice breathed carbogen (95% O2:5% CO2). Additionally, mild hyperthermia followed by carbogen breathing further increased the tumor pO2 and increased radiation cytotoxicity as assessed by the in vivo/in vitro excision assay for surviving FSaII cells. It was concluded that mild hyperthermia in combination with carbogen breathing is potentially useful to reoxygenate radioresistant hypoxic cells and improve the radiotherapy of human tumors.

Gene therapy of spontaneous canine melanoma and feline fibrosarcoma by intratumoral administration of histoincompatible cells expressing human interleukin-2

The production of human interleukin-2 (hIL-2) local to the tumor site by engineered histoincompatible cells has been shown in various murine models to promote a strong immune response leading to tumor growth inhibition or rejection. To assess whether this strategy would be similarly applicable for treatment of primary neoplastic cells, two naturally occurring tumors were used as preclinical models; the highly metastatic melanoma of the dog and the low metastatic fibrosarcoma of the cat. We demonstrate that both cats and dogs when treated by tumor surgery, radiotherapy and repeated local injections of xenogeneic Vero cells secreting high levels of hIL-2 relapse less frequently and survive longer than control animals treated by surgery and radiotherapy alone. Local secretion of hIL-2 by the xenogeneic cells is shown to be necessary for the induction of an optimal antitumor effect. Moreover, the safety of the procedure was demonstrated in both animal models and through extensive toxicological analysis performed in rats. These results confirm for the first time to our knowledge the safety and therapeutic potential of a gene transfer strategy in animals with spontaneous metastatic and nonmetastatic tumors.

Enhancement of radiation effect by Ginkgo biloba extract in C3H mouse fibrosarcoma

BACKGROUND AND PURPOSE

Ginkgo biloba leaf extract (GBE) is known to increase peripheral blood circulation. The hypothesis that GBE may be able to enhance radiosensitivity of tumor by improving tumor blood flow and thus decreasing hypoxic fraction was tested.

MATERIALS AND METHODS

Fibrosarcoma (FSaII) growing in C3H mouse leg muscle was used as a tumor model. GBE was given i.p. 1 h before irradiation with or without priming dose given 1 day earlier. Effect on tumor and normal tissue radiation reaction was investigated.

RESULTS

Tumor growth delay by radiation was more elongated after two doses (1-day interval) of GBE than after a single dose. Radiation dose for 3-day tumor growth delay was decreased from 12.45 (10.97-13.93) Gy to 6.06 (3.89-8.22) Gy by two doses of GBE [enhancement ratio = 2.06 (1.32-2.79)]. Hypoxic cell fraction was 10.6% (6.3-18.2%) for control, 7.2% (3.8-14.0%) after a single dose (P = 0.18) and 2.7% (1.5-5.0%) after two doses (P < 0.001). Radiation effect on normal tissue, estimated by acute skin reaction and jejunal crypt assay, was not affected by GBE.

CONCLUSION

Ginkgo biloba extract enhances radiation effect on tumor without increasing acute normal tissue radiation damage in this model system probably by increasing tumor blood flow and further investigation for this possible radiosensitizer is needed.

Defining the synergistic effects of irradiation and T-cell immunotherapy for murine intracranial tumors

In recent studies, we demonstrated that the systemic adoptive transfer of tumor-draining lymph node (LN) cells, activated ex vivo with anti-CD3 mAb or bacterial superantigens, was effective for treatment of tumors in the brain, an immunologically privileged site. In this study, we demonstrate that sublethal whole body irradiation (WBI) or local cranial irradiation of the tumor-bearing host prior to the adoptive transfer of LN cells, activated with the superantigen, SEC2, augments therapeutic efficacy, whereas body irradiation with cranial shielding is ineffective. WBI prior to tumor inoculation or treatment of tumor-bearing animals with cyclophosphamide to eliminate suppressor cells did not enhance the therapeutic efficacy of adoptively transferred cells. Analysis of brains by immunohistochemistry, 4 days after cell transfer, revealed a dense infiltrate of SEC2-activated T lymphocytes which exclusively express the T cell receptor V beta 8.2 phenotype, of both CD4 and CD8 subsets, throughout the tumors in both irradiated and nonirradiated animals. In addition, MAC-1+ cells were present within tumors irrespective of either irradiation or cell transfer. These findings demonstrate that the systemically transferred T cells could gain access to the tumor located in the CNS. However, the therapeutic enhancement by sublethal irradiation does not reflect an increase in T cell or MAC-1+ cell migration into the tumor.

Effects of interstitial heating on the RIF-1 tumor using an Nd:YAG laser with multiple fibers

BACKGROUND AND OBJECTIVE

Hyperthermia was induced in tumor-bearing C3H mice using a Nd:YAG laser emitting near-infrared radiation at 1,064 nm. The efficacy of multiple implanted fiberoptics in the control of the RIF-1 tumor was investigated.

STUDY DESIGN/MATERIALS AND METHODS

RIF-1 tumors in the right hind leg were heated interstitially at 42, 44, or 46 degrees C for 30 or 60 minutes. Two, three, or four 400-microns quartz fibers terminating in a 1.0-cm cylindrical diffusor were inserted into each tumor, as were five microthermocouples to monitor temperature during treatment. Laser Doppler Flow (LDF) was also recorded pre- and post-treatment to determine changes in red blood cell flux in overlying skin (42, 44, or 46 degrees C) and the center of the tumor (46 degrees C).

RESULTS

These experiments indicated that interstitial heating at 42, 44, and 46 degrees C resulted in tumor growth delay, although long-term control of tumors was not achieved. Treatment using four fibers resulted in the greatest tumor growth delay at 42 and 44 degrees C, increasing tumor doubling time by 50% or greater compared to control tumors; tumor growth delay following 46 degrees C treatments was seven times greater than that in control tumors. Significant changes (decreases) in LDF (P < .05) were seen in four treatment groups, using two fibers at 42 degrees C for 30 minutes, four fibers at 44 and 46 degrees C for 60 minutes on the overlying skin, and 46 degrees C for 60 minutes in the center of the tumor.

CONCLUSIONS

Initial data indicate that interstitial heating with multiple fibers increases tumor growth delay compared to previous single fiber treatments, with tumor growth delay increasing with increasing treatment temperature; however, long-term tumor control was not achieved under the conditions investigated. Follow-up studies will explore the use of higher temperatures and/or longer treatment times in order to optimize tumor response.

Radiation therapy in the treatment of oral neoplasia

Oral neoplasia occasionally may be treated adequately with a single modality. Multimodality therapy, however, more often is indicated. This article reviews the recommendations of treatment of oral neoplasia focusing on the role of radiation therapy both singly and as a part of multimodality therapy.

Modulation of the rat tumor-associated shedding antigen (CE7) and augmentation of immunogenicity by irradiation

We have previously reported that rat fibrosarcoma KMT-17 cells and their in vitro counterparts, cloned A3 cells, shed a tumor-associated antigen (TAA), termed CE7, from the cell surface on vesicular membranes, under growth-enhancing conditions. This study shows that irradiation (1 approximately Gy) from a 60Co source, inhibited A3 cell growth dose-dependently and correspondingly increased CE7 expression by A3 cells as determined by anti-CE7 monoclonal antibody using flow cytometry. CE7 expression gradually increased with increasing doses of irradiation and reached a peak level at 30Gy. After 30Gy irradiation, CE7 expressing A3 cells were fixed with 1% paraformaldehyde and were used to intradermally immunize syngenic rats. Immunized rats developed transplantation resistance to the parent KMT-17 cells as compared to rats immunized with unirradiated A3 cells. Rat MHC class 1 antigen expression was slightly decreased by irradiation and therefore, resistance to tumor transplantation appeared to arise solely due to the enhancing effects of irradiation on TAA expression which increases the antigenicity of the tumor cells coverting them to an effective stimulator of antitumor effector cells. This phenomenon may offer a possibility of the resistance to the re-emergence and metastasis of the tumor like a KMT-17 through the induction of antitumor memory cells.

Genetic radiotherapy overcomes tumor resistance to cytotoxic agents

We report that radiation enhances gene therapy of a radioresistant tumor by upregulating the induction of a chimeric gene encoding a radiosensitizing protein, tumor necrosis factor alpha (TNF-alpha). We ligated the radiation-inducible CArG elements of the radiation-inducible Egr-1 promoter/enhancer region upstream to the transcriptional start site of the human TNF cDNA (pE425-TNF). This construct was transfected using cationic liposomes into the variant murine fibrosarcoma cell line, P4L. The P4L cell line was both radioresistant (D0 = 188) and resistant to TNF. After a single intratumoral injection of 10 micrograms of pE425-TNF in cationic liposomes and two 20-Gy doses of irradiation, mean tumor volumes were significantly reduced in P4L tumors as compared to those receiving either pE425-TNF in liposomes or radiation alone (P = 0.01). TNf protein in P4L tumors was induced by radiation as high as 29 times control levels and remained detectable for 14 days. Our data indicate that combined gene therapy using liposomes, together with ionizing radiation to locally activate the induction of a radiosensitizing protein, is successful at overcoming resistance to both TNF and radiation.

The proliferative capacity of mouse fibrosarcoma cells that survived x-irradiation

Delayed reproductive death, the appearance of colonies with a reduced cell density (impaired colonies) and the number of giant cells per colony were investigated in murine fibrosarcoma cells after irradiation with 3 to 9 Gy of x-rays. Radiation survivors were replated after reaching confluence, which occurred after 13 to 15 doublings; this procedure was repeated three times. The replating efficiency decreased in a dose-dependent manner, the survivors of 9 Gy achieving only 30% of the plating efficiency of unirradiated cells. After the third replating, i.e. after 40 to 45 doublings, the plating efficiency of the survivors approached that of the controls. The median colony size of the survivors showed a similar dose-dependent decrease, which was pronounced after the first replating but still remained significant after the third replating. The fraction of impaired colonies was increased to more than 30% in 9-Gy survivors, and though abating, the increase was still significant even after the third replating. Evidence of residual damage was also provided by the presence of giant cells. For instance, after 6 Gy irradiation and 13 to 15 doublings, the proportion of colonies with giant cells was 60%, decreasing only to 45% after 40 to 45 doublings. The number of giant cells per colony was 1.4 in colonies arising immediately after 6 Gy, decreasing to 0.9 after the third replating. These results suggest that the proliferative capacity of surviving cells is depressed even longer than their clonogenic capacity.

Reversal of radiation-induced cisplatin resistance in murine fibrosarcoma cells by selective modulation of the cyclic GMP-dependent transduction pathway

Cisplatin resistance, induced in murine fibrosarcoma cells (SSK) in vitro or in vivo by low-dose irradiation, can be overcome by activation of the cyclic GMP(cGMP)-dependent transduction pathway. This is mediated either by stimulating cGMP formation with sodium nitroprusside or by replacing cGMP with a selective activator of the cGMP-dependent protein kinase, 8-bromo-cGMP. The cyclic AMP-dependent transduction pathway is not involved in cisplatin resistance. Instead, activation of cAMP sensitises both parental and resistant SSK cells equally to the action of cisplatin. There is a 1.8 to 2.5-fold increase in drug toxicity, depending on the activating agent. Enhancement of cisplatin sensitivity is induced by specific inhibition of cAMP hydrolysis, increase in cAMP formation or by increasing the activation potential to cAMP-dependent protein kinase by specific cAMP analogues. Cells that have lost cisplatin resistance respond to cGMP- or cAMP-elevating agents in the same way as the parental SSK cells. The radiation sensitivity is unchanged in all cell lines, even after activation of cAMP or cGMP. These results suggest that specific DNA repair pathways are altered by radiation but affected only in cisplatin damage repair, which is regulated by cGMP. Although there is ample cooperativity and interaction between the cAMP- and the cGMP-dependent transduction pathways, specific substrate binding by cGMP appears to play an important role in radiation-induced cisplatin resistance.

Expression of manganese superoxide dismutase reduces tumor control radiation dose: gene-radiotherapy

This study investigated the in vitro and in vivo radiation response of tumor cells transfected with human manganese superoxide dismutase (MnSOD) cDNA. A major objective was to test the potential tumor suppressive effect of MnSOD in vivo. Tumor cells studied were an in vitro line derived from a murine spontaneous fibrosarcoma, FSa-II, which expressed an undetectable MnSOD activity. These cells were transfected with pSV2-NEO plasmid (NEO line) or cotransfected with MnSOD plasmid plus pSV2-NEO plasmid (SOD lines) as described previously. The cell lines used were SOD-L and SOD-H, which expressed, respectively, low and high MnSOD activities after transfection, and NEO and parental FSa-II controls. Both SOD-L and SOD-H cell lines were slightly more resistant to ionizing radiation than were the two control cell lines when irradiated in vitro in the presence of oxygen. The dose-modifying factors calculated at the survival level of 0.01 were 1.13 and 1.15 for the SOD-L and SOD-H cells, respectively. To investigate potential tumor suppressive effects, animal tumors of 4 mm diameter were irradiated in vivo under hypoxic conditions, and the radiation dose to control one-half of the irradiated tumors (TCD50) was determined for each tumor. The TCD50S obtained on the basis of the tumor control rate in 120 days after irradiation were substantially lower for the SOD-H and SOD-L tumors compared to the NEO tumors. They were 22.9, 28.6, and 47.5 Gy for SOD-H, SOD-L and NEO tumors, respectively. To analyze these data, survival curves were obtained for hypoxic cells by irradiating NEO and SOD-H tumors under hypoxic conditions in vivo and assaying in vitro. Analysis of these curves suggests that the decrease in the TCD50S of SOD tumors is attributable to the reduced tumorigenicity in these tumors. The hypoxic cell survival curves also showed that SOD did not protect cells from radiation in the absence of oxygen. Electron microscopy showed no morphological differences between these cells. These results suggest that the fraction of tumorigenic cells could be reduced by expression of MnSOD, resulting in a substantial decrease in the TCD50.

Changes of oxygen tension in experimental tumors after a single dose of X-ray irradiation

Electron paramagnetic resonance oximetry was used to measure the partial pressure of oxygen (pO2) in two types of tumor in vivo in C3H/HeJ mice. The pO2 in MTG-B (high hypoxic fraction) and RIF-1 (low hypoxic fraction) tumors was monitored prior to and at several time points after a single dose of X-ray irradiation (up to 7 days after treatment). Initial values of pO2 in RIF-1 (8.7 +/- 1.1 mm Hg; n = 14) were higher than that of pO2 in MTG-B (3.3 +/- 0.5 mm Hg; n = 19). The pO2 in both types of unirradiated tumors decreased slowly with tumor growth. Irradiation of tumors had a two-phase effect on pO2: an initial sharp decrease in pO2, followed by slow reoxygenation. After a 20-Gy radiation dose, the pO2 was 2.2 +/- 0.5 mm Hg at 6 h [significantly lower (P < 0.0001) than in control] and 3.2 +/- 0.5 mm Hg at 48 h [significantly higher (P < 0.02) than in control] in MTG-B, and 5.4 +/- 1.2 mm Hg at 24 h and 8.2 +/- 1.0 mm Hg at 72 h in RIF-1. The time course for these changes in pO2 was found to be independent of the doses in use in this study (10, 20, and 40 Gy). The occurrence of radiation-induced changes in pO2 and the different time courses of these changes suggest that repeated monitoring of pO2 in tumors during treatment could be used to enhance the efficacy of clinical treatments.

Primary fibrosarcoma of the heart

A case of primary fibrosarcoma of the heart, which was diagnosed in a 17 year old man, is presented. Extensive tumour resection and postoperative radiation therapy was carried out. The patient is alive after 18 months after the operation. Although these tumours are associated with very poor survival, early diagnosis and combined therapy may prolong life expectancy.

p53 status and the efficacy of cancer therapy in vivo

The therapeutic responsiveness of genetically defined tumors expressing or devoid of the p53 tumor suppressor gene was compared in immunocompromised mice. Tumors expressing the p53 gene contained a high proportion of apoptotic cells and typically regressed after treatment with gamma radiation or adriamycin. In contrast, p53-deficient tumors treated with the same regimens continued to enlarge and contained few apoptotic cells. Acquired mutations in p53 were associated with both treatment resistance and relapse in p53-expressing tumors. These results establish that defects in apoptosis, here caused by the inactivation of p53, can produce treatment-resistant tumors and suggest that p53 status may be an important determinant of tumor response to therapy.

Sarcomas of nasal cavity and paranasal sinuses: chondrosarcoma, osteosarcoma and fibrosarcoma

Forty-two patients were treated for sarcoma of the nasal cavity and paranasal sinuses at the Institut Gustave Roussy, Paris, between 1960 and 1993. Twelve patients had chondrosarcoma (CS), 14 had osteosarcoma (OS) and 16 had fibrosarcoma (FS). Ten patients had grade I, six grade II and 26 grade III tumours. All but 10 patients had surgery for the primary tumour. A significantly increased risk of local failure was associated with the male sex (p < 0.01), grade III tumours (p < 0.02) and patients excluded from surgery (p < 0.04). The overall incidence of local and distant failure was 76 and 12 per cent respectively. Overall survival was 28 per cent at three years and 23 per cent at five years. Eight patients (20 per cent) were alive more than 10 years later. The factors significantly influencing survival were sex (p < 0.01), grade (p < 0.05) and local failure (p < 0.01).

Cisplatin resistance in mouse fibrosarcoma cells after low-dose irradiation in vitro and in vivo

Murine fibrosarcoma cells (SSK) exhibit a transient cisplatin resistance after low-dose irradiation (5 x 2 Gy) in vitro and in vivo. When resistance is lost, it can be restored by a single drug exposure which, without preirradiation, does not generate cisplatin resistance in parental cells. There is no cross-resistance to radiation. Metallothioneins, which are associated with cisplatin resistance after high-dose irradiation (15 x 6 Gy), do not correlate with induction and loss of cisplatin resistance after low-dose irradiation. Since cisplatin survival curves are also monotonous when drug resistance diminishes, an adaptive response is more likely than a mutational event to underlie cisplatin-induced resistance. Drug resistance can be overcome by combined exposure to cisplatin in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Under these conditions, cisplatin sensitivity is increased 2.4- to 2.8-fold in the resistant strains compared with only 1.5- to 1.8-fold in the parental cells. The cellular platinum content with and without IBMX treatment is not significantly different in sensitive and resistant cells. Loss of drug resistance correlates with a decrease in cisplatin sensitisation by IBMX. This suggests that cisplatin resistance after low-dose irradiation may be associated with alterations of the cAMP-dependent signal transduction pathway.

Improvement of combined modality therapy with cisplatin and radiation using intratumoral drug administration in murine tumors

The aim of these studies was to increase the therapeutic ratio by achieving higher tumor concentrations of cisplatin during the course of a fractionated irradiation treatment. Specific goals were to test, firstly, whether multiple drug injections could be replaced by a single slow release implant of cisplatin, and secondly, whether the therapeutic potential of the combined treatment could be increased by administering the drug intratumorally. Drug administration routes tested were intraperitoneal (i.p.) of drug in solution, intratumoral (i.t.) of drug in solution, and intratumoral of drug in a slow release formulation. The latter consisted of a hydrogel polymer formulated into rods which were implanted into the center of subcutaneous tumors. For drug alone, both i.t. routes (solution or polymer) produced higher therapeutic gains than i.p. administration, as judged by tumor growth delay for a given weight loss. When combined with radiation, dose response curves were always shifted to lower doses and were steeper than for radiation or drug alone, although isobologram analysis indicated additivity. In a first series, drug enhancement ratios ranged from 1.6 to 2.6, and were highest for the i.t. groups. In a second series, X-ray enhancement ratios ranged from 1.1 to 1.7, with overlap between results from the different routes. Therapeutic ratios, however, were highest for the i.t. groups in both series. Slow release rods produced the highest therapeutic gains in the first series, while i.t. administration of drug in solution was approximately as effective in the second series.(ABSTRACT TRUNCATED AT 250 WORDS)

Irradiation of nonlymphoproliferative neoplasms of the nasal cavity and paranasal sinuses in 16 cats

Sixteen cats with malignant tumors (10 carcinomas, 6 sarcomas) of the nasal cavity and paranasal sinuses were treated with curative intent by radiotherapy. Clinical stating was based on radiographic findings, using the tumor, node, metastasis classification system of the World Health Organization. Irradiation was done with a telecobalt-60 unit (13 cats) and an orthovoltage unit (3 cats). Fourteen cats were treated with irradiation alone, and 2 cats had incomplete surgical resections prior to radiotherapy. Treatment dose was 48 Gy (minimum tumor dose), administered by use of 4 Gy per fraction on a Monday/Wednesday/Friday basis over 4 weeks. Survival times after treatment ranged from 1 to 36 months. The 1- and 2-year overall survival rates were 44.3 and 16.6%, respectively. Histologic type and clinical stage did not have prognostic value. Most acute radiation reactions were mild and self-limiting. Chronic ocular complications were seen in 3 cats. These treatment responses compared favorably with those previously described in dogs and cats with intranasal neoplasms treated with teletherapy and provided a perspective for comparison of new treatment methods.

Lipid-associated methylpheophorbide-a (hexyl-ether) as a photodynamic agent in tumor-bearing mice

Liposomes are a potential system for more selective delivery of photosensitizers (PS) to tumors. Pheophorbides are one series of new PS under investigation for use in photodynamic therapy. The pharmacokinetics, anti-tumor response and normal tissue effects of methylpheophorbide-a-(hexyl-ether) (MPH) associated with negatively charged phospholipid vesicles composed of high and low transition temperature lipids were determined in mice. In some preparations monosialoganglioside, which is known to impart long circulation time to liposomes was also included. Normally water-insoluble MPH could be quantitatively incorporated in multilamellar liposomes up to at least 20 mol MPH/mol lipid% for most liposome compositions and sonicated to form clear suspensions. Evidence from electron microscopy and entrapment of aqueous space markers indicated that the particles formed by sonication were not standard liposomes. Anti-tumor responses to light treatment (135 J/cm2, 665 nm argon-dye laser) 24 h after MPH (0.4 mumol/kg) administration were slightly but significantly greater (P < 0.05) for lipid associated MPH compared to MPH solubilized in Tween 80. There were no major differences in tumor uptake and tumor cell photosensitization between lipid or Tween 80 formulations of MPH, whereas, dependent on lipid composition and time after MPH administration, the doses of light required to cause occlusive vascular damage were increased for the lipid formulations. Pharmacokinetic studies showed rapid dissociation between lipids and MPH in vivo. Lipid formulations are useful for solubilizing MPH and may improve the therapeutic effects of this PS.

Apoptosis during photodynamic therapy-induced ablation of RIF-1 tumors in C3H mice: electron microscopic, histopathologic and biochemical evidence

Very little is known about the applicability of the metabolic and biochemical events observed in cell culture systems to in vivo tumor shrinkage following photodynamic therapy (PDT). The purpose of this study was to assess whether PDT induces apoptosis during tumor ablation in vivo. We treated radiation-induced fibrosarcoma (RIF-1) tumors grown in C3H/HeN mice with PDT employing three photosensitizers, Photofrin-II, chloroaluminum phthalocyanine tetrasulfonate, or Pc IV (a promising phthalocyanine developed in this laboratory). Each photosensitizer was injected intraperitoneally and 24 h later the tumors were irradiated with an appropriate wavelength of red light using an argon-pumped dye laser. During the course of tumor shrinkage, the tumors were removed at 1, 2, 4 and 10 h post-PDT for DNA fragmentation, histopathologic, and electron microscopic studies. Markers of apoptosis, viz. the ladder of nucleosome-size DNA fragments, increased apoptotic bodies, and condensation of chromatin material around the periphery of the nucleus, were evident in tumor tissue even 1 h post-PDT; the extent of these changes increased during the later stages of tumor ablation. No changes were observed in tumors given photosensitizer alone or irradiation alone. Our data suggest that the damage produced by in vivo PDT may activate endonucleolysis and chromatin condensation, and that apoptosis is an early event in tumor shrinkage following PDT.

Response of the FSaII fibrosarcoma to antiangiogenic modulators plus cytotoxic agents

The formation of a blood supply (angiogenesis) is critical to the growth of solid tumors. The naturally occurring steroid tetrahydrocortisol, the synthetic cyclodextrin derivative beta-cyclodextrin tetradecasulfate, and the tetracycline derivative minocycline have antiangiogenic activity. Tetrahydrocortisol (125 mg/kg) and beta-cyclodextrin tetradecasulfate (1000 mg/kg) in a 1:1 molar ratio by continuous infusion over 14 days and minocycline (10 mg/kg) administered i.p. daily from day 4 to day 18 postimplantation of the FSaII fibrosarcoma did not alter the growth of the tumor. These antiangiogenic modulators were not cytotoxic toward FSaIIC tumor cells or bone marrow CFU-GM when tumor-bearing animals were treated and cytotoxicity determined by colony formation in culture. The antiangiogenic modulators markedly increased the cytotoxicity of cyclophosphamide toward FSaIIC tumor cells and to a much lesser degree toward bone marrow CFU-GM. The cytotoxicity of CDDP and radiation was enhanced only by administration of the three modulators in combination. In tumor growth delay studies, the three modulator combination increased the effectiveness of CDDP by 1.5-fold, of cyclophosphamide by 1.9-fold and of radiation by 1.4-fold. Although the antiangiogenic therapies alone did not substantially reduce the number of lung metastases compared with the untreated controls, addition of the antiangiogenic agents to treatment with the cytotoxic therapies reduced not only the number of lung metastases formed from the primary tumor but also reduced the number of large metastases. Thus, antiangiogenic therapies can potentiate the efficacy of standard anticancer therapies.

Antitumorous and immunomodulatory effects of the Viscum album L. preparation Isorel

There are numerous data on the immunostimulative and antitumorous activity of various Viscum album tissue extracts. Isorel (Novipharm, Austria) is one of these compounds. We found that in mice an increased number of plaque-forming cells to sheep red blood cells (SRBC) followed the injection of Isorel together with SRBC. Further, survival time of a foreign skin graft was shortened if Isorel was applied at the correct time. Finally, suppressed immune reactivity in tumorous mice recovered following Isorel injection. Isorel was further shown to be cytotoxic to tumor cells in vitro. Its application to tumor-bearing mice could prolong their life but without any therapeutic effect. However, a combination of local irradiation and Isorel was very effective: following 43 Gy of local irradiation to a transplanted methylcholanthrene-induced fibrosarcoma (volume about 240 mm3) growing in syngeneic CBA/HZgr mice, the tumor disappeared in about 25% of the animals; the addition of Isorel increased the incidence of cured animals to over 65%. The combined action of Isorel, influencing tumor viability on the one hand and the host's immune reactivity on the other, seems to be favorable for its antitumor action in vivo.

Timing and sequence of hyperthermia in fractionated radiotherapy of a murine fibrosarcoma

PURPOSE

This study investigated the effect of timing and sequence of hyperthermia on fractionated radiotherapy, since it has been shown that the heat increases the size of hypoxic cell fraction which could affect the effect of subsequent radiation doses.

METHODS AND MATERIALS

Animal-tumors were early generation isotransplants of a spontaneous fibrosarcoma, FSa-II, in C3Hf/Sed mice. Tumor response was studied by tumor growth time and TCD50 (50% tumor control dose) assays. The tumor growth time is the time required for one-half of the treated tumors to reach 500 mm3 from the first treatment day. The TCD50 is a radiation dose to control one-half of the treated tumors for 120 days following treatments. One heat treatment at 43.5 degrees C for 45 min was given in a water bath in combination with fractionated doses independently (24 hr interval) or simultaneously (2 min interval). For the normal tissue study, the mouse foot was treated, and the acute foot reaction was scored daily and averaged. The late foot reaction was scored in animals used in the TCD50 assay that developed no recurrence for 120 days. The RD50(2.0) and RD50(5.0), or total radiation doses to induce an average score of 2.0 (complete epilation) and 5.0 (partial foot atrophy) in 50% of treated animals, were calculated.

RESULTS

Thermal radiosensitization was most prominent when heat was combined simultaneously with the first or last radiation dose in both the tumor growth time and TCD50 assays. However, the thermal enhancement was greatest when heat was given either with the first or last radiation dose in the TCD50 assay; whereas it was greatest when heat was administered with the last radiation dose in the tumor growth time assay. Both acute and late skin reactions were significantly potentiated by heat administered 24 hr before the first radiation dose.

CONCLUSION

A significant observation in this study was that, in both the tumor growth time and TCD50 assays, heat given independently or simultaneously did not result in any therapeutic gain compared to the radiation alone treatment.

A generalized "tumor growth delay" assay for quantifying alterations of tumor regrowth patterns

Tumor growth delay (TGD) is a widely accepted method for in situ assessment of tumor treatment modalities. However, it has some drawbacks: (1) dependency on arbitrary endpoints and, even more serious, (2) lack of alterations of the tumor-growth pattern after treatment. In the present study a generalization of TGD is proposed which is based on the analysis of tumor growth curves by applying the difference equation of the Gompertz function. The advantages of the present method consist primarily of addressing the drawbacks of the classical assay mentioned above: generalized TGD permits a quantitative evaluation of treatment-induced alterations of tumor-growth patterns after treatment as well as estimations of TGD in a classical form by comparing growth curves as entities, i.e. independently of endpoints. The possibility of studying dose-effect relationships of antineoplastic treatment modalities by the generalized TGD is demonstrated by applying this method on experimental chemotherapy and radiotherapy data.

Improved tumour oxygenation and radiosensitization by combination with nicotinamide and pentoxifylline

We hypothesized that the combination of pentoxifylline (PTX) and nicotinamide (NA) can reduce the radioresistance of FSaII murine fibrosarcoma by improving oxygenation of the hypoxic tumour cells. The purpose of this study was to test the hypothesis; first, tumour blood flow after treatment with NA, PTX, and the combination (PTX+NA) was measured using laser Doppler flowmetry. Second, intratumour pO2 after various treatments was measured polarographically using O2 microelectrodes. Third, the radiation response was also measured, i.e. after an exposure to 20 Gy, the time required to reach a four-fold increase in initial tumour volume was 18 days in the saline-treated control group, 21 days in the NA-treated group, 26 days in the PTX-treated group, but was 36 days in PTX+NA treated group. Interestingly, tumour blood flow significantly increased at 10 min after injection of PTX+NA. The mean pO2 in untreated control tumours was 7.5 mmHg, increasing to 13.1 mmHg after 500 mg/kg of NA alone. Repeated injections of PTX with 100 mg/kg/day for 3 days significantly increased intratumour pO2 to 17.2 mmHg. Compared with PTX alone, PTX+NA slightly increased intratumour pO2 from 17.2 to 18.5 mmHg. However, the percentage of regions having values < 2.5 mmHg significantly decreased from 5% with PTX alone to 1% with PTX+NA. In conclusion, single or multiple injections of PTX may increase available O2 in the tumour and thus ameliorate hypoxia in tumour microregions. As previously reported, the subsequent injection of NA may efficiently oxygenate acutely hypoxic cells. Consequently, PTX+NA may increase the radioresponse of tumours by oxygenating chronic as well as acutely hypoxic cells. PTX alone or in combination with NA is potentially useful to radiosensitize tumours.

[Resection of the aortic bifurcation for fibrosarcoma of the inferior vena cava]

Leiomyosarcomas of the lower vena cava are tumours whose prognosis is bad. The best survival opportunities consist of the widest possible exeresis. You will find below two cases that lead us to proceed to a joint exeresis of the aortic and vena cava bifurcation.

Interleukin-1 modulatory effect on the action of chemotherapeutic drugs and localized irradiation of the lip, duodenum, and tumor

PURPOSE

This study was conducted to examine the radioprotective and radiochemoprotective capabilities of interleukin 1 beta (IL-1) on two acute-reacting normal tissues of the C3H mouse, the mucosa of the lip and the duodenum. Also assessed was the modulating effect of IL-1 on tumor growth in the same strain of mice.

METHODS AND MATERIALS

IL-1 was administered to C3H/Km mice in combination with fractionated irradiation, or with cyclophosphamide, cisplatin, or 5-fluorouracil (5FU) followed by irradiation. Normal tissue damage was evaluated in the mouse lip, using a subjective scoring system for tissue reaction, and in the duodenum, using the crypt cell survival assay. RIF-1 fibrosarcoma tumor response was assayed with the regrowth delay method.

RESULTS

IL-1 protected against the acute reaction produced by fractionated irradiation in the lip mucosa, shifting the dose-response curve by 3.8 Gy. IL-1 was protective when injected intraperitoneally 24 hr before CY or c-DDP, which were given immediately before the first of five daily radiation dose fractions. The dose-response curves for cyclophosphamide and cisplatin were shifted 4.0 Gy and 1.6 Gy, respectively. IL-1 did not protect against 5FU toxicity when treatments were administered in that same sequence; however, when 5FU was given 4 or 8 hr before IL-1 and the first radiation dose fraction followed 20 or 16 hr later, there was significant protection and the curves were separated by 1.5 Gy or 3.5 Gy. IL-1 also protected duodenal crypt cells against the cytocidal effect of fractionated irradiation, with a dose difference of 1.5 Gy and an improvement of crypt survival of 11.7%. It was even more protective for these cells against the enhanced drug toxicity when cyclophosphamide or 5FU were administered immediately before the first of five daily radiation doses, with the dose differences of 4.4 and 5.3 Gy, respectively, and improvements of crypt survival of 33.8 and 29.9%, respectively. There was no modification by IL-1 of the effect of irradiation alone on the RIF-1 tumor.

CONCLUSION

This study demonstrates the potential for use of IL-1 as an auxiliary in combinations with chemotherapeutic agents and radiation. It also indicates that for some drugs, such as 5FU, IL-1 effects may be sequence dependent.

The effect of combination therapy of radiation and Z-100, an arabinomannan on tumor growth in mice

The effect of radiation combined with intraperitoneal administration of Z-100, an immunomodulatory arabinomannan extracted from Mycobacterium tuberculosis, was studied using Meth A fibrosarcoma in BALB/c mice and metastasis of Lewis lung carcinoma, 3LL, in C57BL/6 mice. In mice bearing Meth A fibrosarcoma, a moderate degree of growth inhibition was observed in the group of single therapy with Z-100 or radiation (10 Gy). When radiation was combined with Z-100, the tumor growth was significantly inhibited. In mice bearing 3LL, slight inhibition of pulmonary metastasis was observed in the group of single therapy, while significant degrees of inhibition of primary tumor growth and pulmonary metastasis were observed in the combination group. This suggests the usefulness of combined use of Z-100 in radiation therapy.

Interaction of topoisomerase I inhibitors with radiation in cis-diamminedichloroplatinum(II)-sensitive and -resistant cells in vitro and in the FSAIIC fibrosarcoma in vivo

The cytotoxicity of the topoisomerase-I inhibitors, camptothecin and topotecan, toward the SCC-25 human head-and-neck squamous-carcinoma cells and the SCC-25/CDDP sub-line made resistant to cis-diamminedichloroplatinum(II) was assessed alone and in combination with radiation. Topotecan was less cytotoxic than camptothecin in cell culture and the SCC-25/CDDP cell line was more sensitive to either topoisomerase-I inhibitor than was the parental SCC-25 cell line. Both camptothecin and topotecan were effective radiation sensitizers of hypoxic SCC-25 and SCC-25/CDDP cells under normal pH or acidic pH conditions. Sensitizer-enhancement ratios ranged between 1.5 and 1.6 for hypoxic SCC-25 cells and between 1.3 and 1.5 for hypoxic SCC-25/CDDP cells. When the ability of camptothecin or topotecan to sensitize the FSallC fibrosarcoma to single-dose radiation was assessed using the tumor-cell-survival assay, a sensitizer-enhancement ratio of 1.2 was found with each drug. However, using tumor growth delay of the FSaIIC fibrosarcoma to determine the effect of camptothecin or topotecan to enhance the efficacy of a daily fractionated radiation regimen, topotecan produced a sensitizer-enhancement ratio of 1.4, while that for camptothecin was 1.2. These results indicate that topoisomerase-I inhibitors may retain activity in CDDP-resistant cells and may be effective adjuncts to radiation therapy.

Combination of interleukin-2 and irradiation in therapy of murine tumors

Experiments were designed to investigate the therapeutic efficacy of interleukin-2 (IL-2) combined with radiotherapy. The effect of IL-2 and local thoracic irradiation (LTI) was determined on 4-day-old lung micrometastases, generated by i.v. injection of tumor cells into mice. IL-2 alone reduced the number of lung nodules more effectively when given from 1 to 4 than 4 to 7 days after tumor cell injection. The combination of IL-2 and LTI reduced the number of lung nodules more than did the individual treatments alone. When IL-2 therapy was combined with local irradiation of 8-mm leg tumors, there was no change in the TCD50 (radiation dose yielding 50% local tumor control). However, the combination of IL-2 treatment on days 1-4 with irradiation of tumor-bearing legs on day 1 after inoculation of tumor cells reduced the TCD50 by a factor of 1.3. These results show that IL-2 improves tumor radiotherapy, but that the improvement depends on anatomic localization and tumor size at the time of treatment.

Description of a spheroid model for the study of radiation and chemotherapy effects on hypoxic tumor cell populations

The presence of poorly oxygenated cells in solid tumors may account for clinical resistance to ionizing radiation and some chemotherapy in many cancers. Studies of the presence and spatial distribution, sensitivity to cancer therapies, and other physiological characteristics of hypoxic cells are hindered by the lack of markers specific for hypoxia and a relevant yet easily manipulated model system. We have chosen to use multicellular spheroids composed of murine EMT6 (fibrosarcoma) tumor cells as a model system and have applied an immunohistochemical marker specific for hypoxic cells with the ultimate goal of determining how cell populations change in response to radiation and/or chemotherapy. Large spheroids (500-700 microns in diameter) were selected and incubated in the presence of a hexafluorinated 2-nitroimidazole derivative, designated CCI-103F, which undergoes reductive metabolism and irreversibly binds to cellular macromolecules only under low oxygen tensions. A rabbit polyclonal antibody raised against a CCI-103F/protein adduct was used to visualize hypoxic cells using standard streptavidin-biotin-peroxidase immunohistochemical methods. Investigations using this spheroid model system promise to further our understanding of hypoxic cell resistance to cytotoxic therapies and of hypoxic cell biology in general.

Therapeutic gain of local and radical resection combined with postoperative radiation for murine fibrosarcomas

Resection of 8-mm fibrosarcomas (FSaII) growing in the right leg of syngeneic C3H/Sed mice was performed under a dissecting (x8) microscope. Local and radical resection achieved 20% (5/25) and 48% (12/25) tumor control, respectively. TCD80s (average dose expected to control 80% of irradiated tumors) for radiation alone given as one fraction per day for 5 consecutive days were 73.1 and 118.0 Gy for the microscopic and 8-mm tumors, respectively. Radiation therapy started at 4 or 7 days following local or radical resection enhanced both the local tumor control and the treatment-related morbidity represented by leg shortening. From enhancement ratios (ERs) for tumor control (TCD80 for radiation alone/TCD80 for postoperative radiation) and for leg shortening (dose for 5-mm leg shortening for radiation alone/postoperative radiation) values, therapeutic gain factors (TGFs) were derived as ER tumor/ER leg shortening. These were 1.3 and 1.4 for local and radical resection followed by radiation started on the 7th postoperative day, respectively. Corresponding figures for radiation started on the 4th postoperative day resulted in 1.2 for both resection procedures.