Treatment regimens including the multitargeted antifolate LY231514 in human tumor xenografts.

The scheduling of antifolate antitumor agents, including the new multitargeted autofolate LY231514 (MTA), with 5-fluorouracil was explored in the human MX-1 breast carcinoma and human H460 and Calu-6 non-small cell lung carcinoma xenografts to assess antitumor activity and toxicity (body weight loss). Administration of the antifolate (methotrexate, MTA, or LY309887) 6 h prior to administration of 5-fluorouracil resulted in additive growth delay of the MX-1 tumor when the antifolate was methotrexate or LY309887 and greater-than-additive tumor growth delay (TGD) when the antifolate was MTA. In the H460 tumor, the most effective regimens were a 14-day course of MTA or LY309887 along with 5-fluorouracil administered on the final 5 days. In addition, the simultaneous combination of MTA administered daily for 5 days for 2 weeks with administration of gemcitabine resulted in greater-than-additive H460 TGD. MTA was additive with fractionated radiation therapy in the H460 tumor when the drug was administered prior to each radiation fraction. MTA administered along with paclitaxel produced greater-than-additive H460 TGD and additive responses along with vinorelbine and carboplatin. In the Calu-6 non-small cell lung carcinoma xenograft, MTA administered in combination with cisplatin or oxaliplatin was highly effective, whereas MTA administered in combination with cyclophosphamide, gemcitabine, or doxorubicin produced additive responses. Administration of MTA along with paclitaxel or doxorubicin resulted in additive MX-1 TGD. Thus, MTA appears to be especially effective in combination therapies including 5-fluorouracil or an antitumor platinum complex.     

Combined effects of the orally active cisplatin analog, JM216, and radiation in antitumor therapy

Purpose: We evaluated the orally administered platinum agent, JM216, in combination with ionizing radiation both in vivo and in vitro against human tumor cells. Methods: H460 human lung carcinoma cells were used as a subcutaneous xenograft in nude mice. JM216 (30 mg/kg) was administered orally, and radiation treatments (2 Gy) were given 1 h after JM216 delivery for five consecutive days. For in vitro analysis, attached H460 cells were treated with JM216 (15 μM) for 1 h and then irradiated. Cells were rinsed 20 min later, and survival was determined by clonogenic assay. Results: Tumor growth delay measurements showed that the combination of JM216 and radiation was additive in vivo, with an enhancement ratio of 1.24. In vitro clonogenic survival experiments demonstrated a dose enhancement ratio of 1.23. Isobologram analysis showed that this interaction was also additive. Conclusions: These data demonstrate that the combination of JM216 and fractionated radiotherapy is more effective against human lung cancer xenografts than either agent alone, and the in vivo results were supported by those observed using an in vitro system with the same tumor cell line. Received: 20 December 1999 / Accepted: 24 May 2000     

Whole-body hyperthermia and lonidamine as adjuvant therapy to treatment with cisplatin with or without local radiation in mouse bearing the Lewis lung carcinoma

The Lewis lung carcinoma implanted subcutaneously in the hind leg of a C57BL mouse metastasizes avidly to the lungs of the host. This tumour model system thus allows assessment of both primary and metastatic disease to treatment. Lonidamine (50 mg/kg) administered once or twice daily produced approximately additive tumour growth delay with whole-body hyperthermia (60 min to 42°C and 60 min at 42°C). The addition of lonidamine to treatment with cisplatin (10 mg/kg) and whole-body hyperthermia continued to produce increased tumour growth delay of up to 14·7 days compared with 10·8 days for cisplatin/whole-body hyperthermia. The response of the metastatic disease paralleled that of the primary tumour with a reduction in the number and percent of large metastases (> 3 mm) on day 20 post-tumour implantation. The addition of local fractionated radiation therapy (3 Gy × 5) to the primary tumour produced a very effective treatment regimen resulting in 37·5 days of tumour growth delay along with twice daily lonidamine/cisplatin whole-body hyperthermia. With this treatment regimen there was also a reduction to 50% of control of the number of lung metastases as well as the percent of large metastases on day 20. Further investigation of these treatment combinations is warranted.     

The potentiation of the effect of radiation treatment by intratumoral delivery of cisplatin

Purpose: To compare potentiation of the effects of acute or fractionated radiation by cisplatin when the drug was delivered intratumorally by implanted biodegradable polymer, by intraperitoneal injection, or by intraperitoneal osmotic pump.Methods and Materials: Radiation was delivered to a mouse tumor (RIF-1) either in a single dose or in a fractionated regime in conjunction with cisplatin delivered either as a bolus injection, with an osmotic pump, or with a biodegradable polymer rod containing cisplatin. The osmotic pump was implanted in the intraperitoneal cavity of the mouse while the polymer implants were placed directly in the tumor. As the polymer degrades, the drug is released at the treatment site leading to high local concentrations. The osmotic pump, in contrast, leads to prolonged systemic exposure to the drug at low concentrations. Tumor growth delay (TGD) was used as an endpoint in these experiments.Results: The most effective treatment protocol, in terms of potentiating the effects of radiation was cisplatin delivered by polymer implanted 2 days before an acute dose of radiation (growth modification factor [DMF] = 2.2). Comparison of single and multifraction regimes where polymer implant was on the same day as the commencement of treatment showed greater potentiation of the effect of fractionated than of acute radiation treatment with the DMF for fractionated treatment remaining relatively constant (1.5–1.9) for 5, 8, and 12 fraction treatments. Cisplatin delivered via the osmotic pump did not deliver a high enough dose of cisplatin to produce therapeutic effect in this mouse tumor model and had little impact on response to treatment.Conclusions: Our results indicated that cisplatin delivered intratumorally by biodegradable polymer implant was effective in potentiating the effect of both acute and fractionated radiation. For the fractionated treatments the effect was maintained with increasing fraction numbers and treatment time.     

Chemopotentiation in vivo: no loss of sensitization with fractionation

The response of KHT sarcomas to one, two, five or ten daily fractions of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), with and without misonidazole (MISO), was evaluated using delay of tumour regrowth as the measure of response. When CCNU was given as 2 dose fractions separated by 24 h rather than as a single treatment, no extra dose was necessary to achieve a particular level of damage, suggesting a lack of damage repair. With increasing fraction number, however, an increasing total dose of drug was required to achieve a given effect, presumably to compensate for proliferation. Increasing drug doses also were readily tolerated (almost twice the LD50/7 for a single dose of CCNU resulted in no deaths when given in a 10 fraction treatment) indicating a large sparing of normal tissue toxicity when CCNU treatments were fractionated. The addition of MISO enhanced the tumour response to CCNU in all treatment schemes. When single doses of CCNU were combined with 0.5 mg g-1 MISO, an enhancement ratio (ER) of approximately 1.5 was observed. This ER was maintained for all fractionated treatment schedules including the 10 daily fraction protocol. In addition, no loss of sensitization with increasing fractionation was observed when a lower dose of 0.2 mg g-1 MISO was combined with each of 5 or 10 daily fractions of CCNU. Similar experiments were performed to test the combination of cyclophosphamide (Cy) and MISO (0.5 mg g-1) in the RIF-1 tumour; again chemopotentiation was maintained with increasing fractionation. These results of combined MISO and fractionated chemotherapy are in contrast to the rapid loss of sensitization observed when MISO is used as a radiation sensitizer and combined with small doses of X-rays, thus providing in vivo evidence of the mechanistic difference between the effects of MISO used as a radiation sensitizer or chemopotentiator. Peripheral white blood cell counts performed on mice receiving 5 daily fractions of CCNU +/- MISO displayed no significant enhancement of normal tissue toxicity by MISO. Thus combining MISO with repeated low dose treatments of a chemotherapeutic agent results in a therapeutic gain.     

Four-hourly scheduling of temozolomide improves tumour growth delay but not therapeutic index in A375M melanoma xenografts

Purpose: To establish whether temozolomide is more effective against A375M human melanoma xenografts if given every 4 h rather than every 24 h, in order to exploit depletion of the DNA repair protein O ⁶-alkylguanine-DNA alkyltransferase (ATase) by prior doses of the drug. Methods: ATase depletion in A375M human melanoma xenografts was determined over 24 h after a single dose of temozolomide. The effect of different drug schedules (all of total dose 500 mg/kg) in delaying the growth of the xenografts was tested, and ATase depletion and DNA methylation damage assessed in tumour and normal tissue. Results: Maximal depletion of ATase in tumour, to 2.52 ± 0.23% of pretreatment levels, occurred 4–8 h after a single 100 mg/kg i.p. dose of temozolomide, with 23.0% recovery of protein levels at 24 h. Scheduling of temozolomide every 4 h increased tumour growth delay (33.6 ± 1.39 days with temozolomide 100 mg/kg 4-hourly ×5 versus 23.2 ± 1.43 days with temozolomide 100 mg/kg once daily ×5; P < 0.0001) at the expense of increased toxicity (17.4 ± 1.55% animal weight loss versus 10.6 ± 1.27%, respectively). Temozolomide every 4 h did not increase ATase depletion compared with the 5-day schedule, but resulted in greater DNA O ⁶-guanine methylation (29.0% more in tumour, 20.8% in liver and 56.0% in brain, comparing areas under the methylation-time curve). Conclusions: The 4-hourly schedule of temozolomide delayed tumour growth significantly more than the once-daily and 12-hourly schedules, probably as a result of greater DNA damage inflicted, but also increased toxicity. It remains to be seen if this regimen confers a net benefit over the standard schedule. Received: 12 March 1999 / Accepted: 9 August 1999     

Phase I study of cisplatin and irinotecan combined with concurrent hyperfractionated accelerated thoracic radiotherapy for locally advanced non-small cell lung carcinoma

Background Irinotecan, when combined with cisplatin, is an effective treatment for advanced non-small cell lung cancer (NSCLC). This constitutes a rationale for conducting a phase I study of chemoradiotherapy including this combination for locally advanced NSCLC. Patients and methods Patients with locally advanced NSCLC and a performance status of 0 or 1 were eligible. The protocol consisted of escalating doses of irinotecan on days 1 and 15, and daily low-dose cisplatin (6 mg/m² daily for a total dose of 120 mg/m²) combined with concurrent hyperfractionated accelerated thoracic irradiation (1.5 Gy twice daily for a total dose of 60 Gy). Results The maximum tolerable dose was 50 mg/m² of irinotecan, and the dose-limiting toxicity was esophagitis. Tumor response was observed in 50% of cases, and the median survival time of the 12 patients enrolled was 10.1 months, including two patients with 5-year disease-free survival. A pharmacokinetics study demonstrated an accumulation of total platinum, but not of free platinum, during the 26-day treatment period. Conclusion The recommended dose for phase II studies was determined.     

The interaction of cisplatin plus etoposide with radiation +/- hyperthermia

The addition of concurrent etoposide and cisplatin to radiation +/- hyperthermia was evaluated in the murine FSaIIC fibrosarcoma tumor system. Tumor growth delay (TGD) demonstrated that when the drugs were tested with radiation (3 Gy daily X 5) plus (43 degrees X 30 min) local hyperthermia, cisplatin/hyperthermia/radiation (TGD approximately 25 days) was significantly more effective than etoposide/hyperthermia/radiation (TGD approximately 14 days). The addition of etoposide to cisplatin/hyperthermia/radiation, however, yielded a significantly longer growth delay (approximately 34 days). Tumor cell survival studies demonstrated that hyperthermia (43 degrees C, 30 minutes) was dose modifying for etoposide cytotoxicity (dose modifying factor approximately 2.0 as determined by comparisons of the slopes of the curves). The addition of etoposide to cisplatin modified cisplatin killing only slightly at 37 degrees C or 43 degrees C. Considerable additional cell kill was observed over a range of radiation doses with cisplatin, hyperthermia, and etoposide added singly or in combination, especially at the lowest radiation dose tested (5 Gy), but essentially no dose modification was observed. Evaluation of Hoechst 33342 dye-selected tumor subpopulations demonstrated that cisplatin, etoposide, radiation (10 Gy), etoposide plus radiation, and cisplatin plus radiation killed significantly fewer dim (presumably hypoxic) cells than bright (presumably normally oxygenated) cells. Hyperthermia killed more dim than bright cells. The combination of hyperthermia with cisplatin and radiation, however, resulted in approximately 5-fold lesser kill in dim cells, and the addition of etoposide increased this differential to 6.4-fold. These results indicate that etoposide adds small but measurable antitumor effects when used with cisplatin alone or with cisplatin in combination with radiation +/- hyperthermia (especially at lower radiation fraction sizes).     

Solid tumor models for the assessment of different treatment modalities: XXIII. A new approach to the more effective utilization of radiotherapy alternated with chemotherapy

This study with the rat hepatoma 3924A demonstrated the marked improvement in tumor cure rates and control of tumor growth that can be achieved by the addition of cyclophosphamide (CP) to multiple fractions of radiation per day (MFD) schedules given intermittently. MFD radiation was delivered over a 2-day period followed by CP (150 mg/kg or 0.9 g/m2) 1 day later; this combined course was repeated at 11-day intervals (to allow for gastrointestinal tract and bone marrow recovery) for a total of 3 courses over a 23-day period. Cure rates of 30, 50 and 60% were achieved with total radiation doses of 4500, 6000 and 7500 rad, respectively, when the MFD radiation was given with CP. No cures and no complete responses were realized when the same intermittent MFD schedules for radiation were employed up to 9000 rad without CP. Other groups of 10 animals each were treated with daily fractions of 100, 150, 188, 250 and 375 rad given on days 0-9, 11-20 and 22-31. A 150 mg/kg or 0.9 g/m2 dose of CP was given after each course of daily radiation on days 10, 21 and 32 in the combined treatment groups. No complete responses or tumor cures occurred with radiation alone given daily for total radiation doses, which were increased from 3000 to 11,250 rad. Only the highest radiation dose given, 375 rad per day to a total of 11,250 rad, resulted in a complete response rate and tumor cure rate of 50% when CP was added. The addition of CP to the daily fractionation schedules reduced the total dose needed to give a growth delay of 100 days by 39% (5600 rad versus 9200 rad). The addition of CP to the intermittent MFD schedules further reduced the total dose needed to give a growth delay of 100 days to 4200 rad. Major improvements in some types of cancer treatment may be realized if we can develop clinical protocols for the alternate use of chemotherapy and radiotherapy as we have done successfully in our experimental program. The finding that intermittent MFD radiation schedules are as effective as daily schedules when given alone suggests that greater flexibility of patient management in clinical radiotherapy may be possible without a major loss of therapeutic effectiveness. These alternated fractionated schedules offer the possibility of optimizing treatment in terms of patient convenience and economy as well as the potential for improving the effectiveness of the interaction of radiotherapy with radiosensitizers, radioprotectors, and hyperthermia in addition to chemotherapy.     

Antitumor activity of cryptophycins: effect of infusion time and combination studies

Introduction/Purpose: Cryptophycins are a family of antitubulin antitumor agents. A synthetic cryptophycin derivative (LY355703, CRYPTO 52) is in early clinical evaluation. The effect of infusion time on the antitumor activity of four cryptophycins was assessed in rats bearing the 13762 mammary carcinoma and combination treatment regimens were assessed in nude mice bearing human tumor xenografts. Methods: The cryptophycins were prepared in 2% PEG300/8% cremophor/90% normal saline and delivered by jugular vein catheter on days 7, 9 and 11 post tumor implant to 13762 tumor-bearing rats. The cryptophycins prepared in the same formulation were administered by intravenous bolus injection on an alternate day schedule for five doses to human tumor xenograft bearing nude mice. Results: An infusion time of 2 h in the rats increased the tumor growth delay produced by CRYPTO 52 and CRYPTO 55, while increasing the infusion time to 6 h continued to increase the tumor growth delay for CRYPTO 292 and CRYPTO 296. Administering CRYPTO 292 at a higher dose two times was more effective than administering it at a lower dose three times. The tumor growth delays produced by the cryptophycins in the rat 13762 mammary carcinoma were greater than those with cisplatin, doxorubicin, 5-fluorouracil and 5 × 3 Gray and comparable with cyclophosphamide and gemcitabine. Combination studies were carried out in human tumor xenografts including the MX-1 breast carcinoma, the Calu-6 non-small cell lung carcinoma, the H82 small cell lung carcinoma and the SW-2 small cell lung carcinoma. CRYPTO 52 and CRYPTO 55 combined with doxorubicin, paclitaxel and 5-fluorouracil to form highly effective regimens against the human MX-1 breast carcinoma. CRYPTO 52 and CRYPTO 55 were also highly effective against the three lung carcinoma xenografts when combined with the antitumor platinum complexes, cisplatin, carboplatin or oxaliplatin. Conclusions: Cryptophycins represent a promising new class of antitumor agents that may be optimally administered by intravenous infusion and in combination with doxorubicin, paclitaxel and 5-fluorouracil. Received: 18 November 1999 / Accepted: 16 March 2000     

Maximizing therapeutic gain with gemcitabine and fractionated radiation

Purpose/Objective: The nucleoside analogue gemcitabine inhibits cellular repair and repopulation, induces apoptosis, causes tumor growth delay, and enhances radiation-induced growth delay. After single doses of drug and radiation, maximum enhancement of tumor response was obtained when gemcitabine preceded radiation by at least 24 h. Conversely, the cellular radioresponse of the normal gastrointestinal epithelium was slightly protected when gemcitabine and radiation were separated by 24 h. This differential response created a time frame within which therapeutic gain could be maximized. In our present investigation, we sought to define the most therapeutically beneficial scheme of gemcitabine administration when combined with fractionated radiotherapy.

Methods and Materials: C3Hf/Kam mice were given identical drug and radiation schedules of administration, and both normal tissue (jejunal mucosa) and tumor (Sa-NH) responses were measured. Irradiation was given once per day for 5 days in normal tissue and tumor growth delay studies and twice per day for the tumor cure endpoint. A total dose of 25 mg/kg gemcitabine was given i.p. in 1 of 3 schedules: a single dose of 25 mg/kg 24 h before the start of fractionated irradiation, 12.5 mg/kg 24 h before the first and third radiation doses, or 24 h before each of 5 radiation doses. Groups of mice bearing 7- or 8-mm diameter tumors were treated with gemcitabine alone or in combination with fractionated irradiation under ambient or hypoxic conditions. The survival response of the jejunal mucosa was quantified by the microcolony assay and histologically by quantifying apoptosis, mitosis, S-phase fraction, and crypt cellularity.

Results: For tumor growth delay, dose-modifying factors (DMFs) were similar (1.34–1.46) for all 3 schedules of drug administration. In contrast, the response of the jejunum was strongly dependent on the schedule of gemcitabine administration. A single dose of gemcitabine before the start of fractionated radiotherapy resulted in slight radioprotection (DMF 0.96). Two doses and 5 daily doses of gemcitabine enhanced radiation response by factors of 1.09 and 1.23, respectively. Major factors affecting the response of the jejunal mucosa were apoptotic death of S-phase cells exposed to gemcitabine and cell cycle synchrony of surviving cells. Tumor reoxygenation was found to be a major mechanism for tumor radioenhancement, in addition to those reported earlier.

Conclusion: All 3 schedules of drug administration produced therapeutic gain; however, when gemcitabine was given more than once in a 5-fraction radiation treatment schedule, normal tissue toxicity increased. The highest therapeutic gain (1.4) was achieved by giving a single dose of gemcitabine (25 mg/kg) 24 h before the start of fractionated radiotherapy.     

Use of tetrahydraindazolone dicarboxylic acid (HIDA) to improve the therapeutic effect in vivo of combined cisplatin,heat and radiation treatment

The effect of tetrahydraindazolone dicarboxylic acid (HIDA) on tumour response and mouse lethality after treatment with cisplatin given either alone or combined with hyperthermia (43-5d`C/60 min) with or without radiation, was studied in the CDF, mouse bearing a foot transplanted C<sub>3</sub> H mouse mammary carcinoma. The tumour response to a combined heat, cisplatin and HIDA treatment was assessed by tumour growth time, while local tumour control was used when irradiation was added to that treatment scheme. Toxicity was estimated as lethality within 14 days. Cisplatin and heat exerted the highest antitumour effect when given simultaneously, but at the same time there was a substantial increase in lethality. No sensitization of the tumour response or enhanced toxicity to cisplatin was observed if heat was given sequentially (i.e. 4 h) after cisplatin. The effect of this sequential schedule being only additive. When HIDA (100 mg/kg) was given 150 min before cisplatin and tumours heated 15 min later, the lethal toxicity was significantly reduced. HIDA did not, however, influence tumour growth time results. In tumour control studies combining radiation, drug and heat, cisplatin (6 mg/kg) and heat (43 -5d`C/60 min) were given simultaneously 4 h after local irradiating the leg of tumour-bearing mice. The lethality of this regime was more than 55 %, but when HIDA was added to the protocol, the toxicity fell to 5 % without affecting local tumour control. In conclusion, HIDA administered before cisplatin protects against drug-induced toxicity without reducing the drug's antitumour activity when used alone or in combination with hyperthermia and/or radiation, and thus results in a significantly improved therapteutic benefit.     

The effect of cisplatin on the repair of radiation damage in RIF1 mouse tumours in vivo

The effect of the antitumour agent cisplatin on repair of X-ray-induced damage was studied in RIF1 mouse tumours treated in situ. The response of tumours, assessed by growth delay, to 4 fractions of X-rays given at 5-h intervals was compared with that after single doses. The displacement between the curves was taken as a measure of repair. A single dose of 6 mg.kg-1 cisplatin given 0.5 h before the first fraction resulted in no detectable inhibition of repair despite a significant growth delay caused by drug alone. A dose of 2 mg/kg cisplatin given 0.5 h before each of the X-ray fractions did, however, cause some repair inhibition; a result confirmed by tumour control experiments. The schedule dependence for repair inhibition was the same whether the irradiations were carried out on clamped (fully hypoxic) tumours or under ambient conditions. Significant enhancement of radiation damage was seen after correcting for the effects of drug alone, whether or not repair inhibition occurred. The effects of cisplatin on normal stroma within the tumour (vascular damage) was also investigated by monitoring the regrowth rates of recurrent tumours. In contrast to the effects on tumour cells, no enhancement of damage or inhibition of repair was seen for this assay in the combined treatment schedules.     

Enhancement of radiation response by inhibition of Aurora-A kinase using siRNA or a selective Aurora kinase inhibitor PHA680632 in p53-deficient cancer cells

Overexpression of Aurora-A kinase has been correlated with cancer susceptibility and poor prognosis in several human cancers. In this study, we evaluated the effect of inhibition of Aurora-A kinase on cell cycle progression and tumour cell survival after exposure to ionising radiation (IR). Combined IR and Aurora-A inhibition by short interfering RNA (siRNA) or by PHA680632 (a selective Aurora kinase inhibitor with submicromolar activity against Aurora-A) prior to IR led to an enhancement of radiation-induced annexin V positive cells, micronuclei formation, and Brca1 foci formation only in cells with deficient p53. However, the drug brought about additive to sub-additive interaction with radiation with regard to in vitro clonogenic survival. Cell cycle analysis revealed a high >4N DNA content 24 h after PHA680632 exposure. DNA content >4N was reduced dramatically when cells were irradiated combined with PHA680632 simultaneously. In vivo xenografts (p53-/- HCT116) of a mice study showed enhanced tumour growth delay (TGD) after the PHA680632-IR combinatorial treatment compared with IR alone. These results demonstrate that PHA680632 in association with radiation leads to an additive effect in cancer cells, especially in the p53-deficient cells, but does not act as a radiosensitiser in vitro or in vivo.     

Addition of mitomycin C to cis-diamminedichloroplatinum(ii)/ hyperthermia/radiation therapy in the FSaIIC fibrosarcoma

Hyperthermia (temperatures<42°) is used clinically to improve the effectiveness of radiation therapy and, although therapeutic gains have been reported, efficacy is limited when tumours are large and/or radiation tolerance is reduced. In order to improve the utility of the hyperthermia/radiation combination we have tested the addition of cisplatin (CDDP) in the laboratory and in the clinic. Our clinical studies have shown that the CDDP/hyperthermia/radiation combination is tolerable and effective, but laboratory investigations demonstrated a relative lack of cytotoxicity in the hypoxic tumour subpopulation. In order to improve the effectiveness of the CDDP/hyperthermia/radiation combination against hypoxic cells we have evaluated the addition of mitomycin C, a hypoxic cell cytotoxic agent to this combination. Mitomycin C (5 mg/kg) i.p. produced a tumour growth delay (TGD) of about 5.3 days in the FSaIIC murine fibrosarcoma; hyperthermia (43°±30 min) caused only about 1.4 day TGD and the combination of mitomycin C followed immediately by hyperthermia caused a TGD of about 8.6 days. CDDP (5 mg/kg) i.p. followed by hyperthermia and then 3 Gy on day 1 only of a 5 day ± 3 Gy radiation protocol produced a TGD of about 25 days. With the addition of mitomycin C just before CDDP a TGD of about 44 days resulted. Whole tumour excision experiments demonstrated that mitomycin C was highly interactive with CDDP at 37° and was dose-modifying. When used with CDDP and hyperthermia, however, mitomycin C added little additional cytotoxicity. Hoechst 33342 dye diffusion-determined tumour subpopulation studies indicated a marked effect of the addition of mitomycin C in the dim (enriched in hypoxic cells) subpopulation and nearly equal cytotoxicity in both bright (enriched in euoxic cells) and dim cells resulted. These investigations suggest considerable potential therapeutic efficacy to the addition of mitomycin C to the CDDP/hyperthermia/radiation combination.     

Combinations of CCNU, MISO, and fractionated radiotherapy

Studies were performed to determine whether the radiation sensitizer misonidazole (MISO) could enhance the tumor response of the KHT sarcoma to a treatment combining fractionated radiotherapy and the chemotherapeutic agent 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU). A single dose of CCNU (20 mg/kg) was given 24 hr prior to the start of a multi-fraction radiation protocol in which 10 fractions were delivered once a day in 12 days overall treatment time. Daily radiation doses ranged from 1.0 to 4.0 Gy. MISO was administered at a dose of 1.0 mmol/kg, either once as a chemopotentiator simultaneously with CCNU, or repeatedly as a radiosensitizer 30-40 min prior to each radiation dose. Tumor response to treatment was assessed using tumor regrowth delay as the end point. The results indicate that, at 1.0 mmol/kg, MISO failed to radiosensitize the tumors in each of the fractionation schedules evaluated; that is, there was no difference between the regrowth delay curves obtained when CCNU treatment was followed by fractionated radiation, administered either alone or with MISO prior to each radiation dose fraction. However, when a single dose of 1.0 mmol/kg MISO was combined with CCNU 24 hr prior to the start of radiotherapy, regrowth delay was increased for all fractionated radiation schedules, particularly, at the larger dose fraction sizes. Comparison of the dose response curves suggests that MISO, used as a chemopotentiator, effectively reduced the proportion of radiobiologically hypoxic cells in the tumors prior to the start of the radiation therapy. These findings indicate that chemopotentiation can be used effectively in a combination with fractionated radiotherapy.     

An intergroup phase III comparison of standard radiation therapy and two schedules of concurrent chemoradiotherapy in patients with unresectable squamous cell head and neck cancer.

PURPOSE: The Head and Neck Intergroup conducted a phase III randomized trial to test the benefit of adding chemotherapy to radiation in patients with unresectable squamous cell head and neck cancer. PATIENTS AND METHODS: Eligible patients were randomly assigned between arm A (the control), single daily fractionated radiation (70 Gy at 2 Gy/d); arm B, identical radiation therapy with concurrent bolus cisplatin, given on days 1, 22, and 43; and arm C, a split course of single daily fractionated radiation and three cycles of concurrent infusional fluorouracil and bolus cisplatin chemotherapy, 30 Gy given with the first cycle and 30 to 40 Gy given with the third cycle. Surgical resection was encouraged if possible after the second chemotherapy cycle on arm C and, if necessary, as salvage therapy on all three treatment arms. Survival data were compared between each experimental arm and the control arm using a one-sided log-rank test. RESULTS: Between 1992 and 1999, 295 patients were entered on this trial. This did not meet the accrual goal of 362 patients and resulted in premature study closure. Grade 3 or worse toxicity occurred in 52% of patients enrolled in arm A, compared with 89% enrolled in arm B (P <.0001) and 77% enrolled in arm C (P <.001). With a median follow-up of 41 months, the 3-year projected overall survival for patients enrolled in arm A is 23%, compared with 37% for arm B (P =.014) and 27% for arm C (P = not significant). CONCLUSION: The addition of concurrent high-dose, single-agent cisplatin to conventional single daily fractionated radiation significantly improves survival, although it also increases toxicity. The loss of efficacy resulting from split-course radiation was not offset by either multiagent chemotherapy or the possibility of midcourse surgery.     

C225 antiepidermal growth factor receptor antibody enhances the efficacy of docetaxel chemoradiotherapy

PURPOSE: C225 anti-EGFR (epidermal growth factor receptor) antibody has been shown to enhance tumor response to radiation and a number of chemotherapeutic agents. Because of increased use of concurrent chemoradiotherapy in cancer treatment, it is important to determine whether C225 enhances also the antitumor efficacy of radiation when combined with chemotherapy. This study assessed the effect of C225 on tumor response when combined with docetaxel plus single or fractionated radiation. METHODS AND MATERIALS: MDA468 human adenocarcinoma and A431 human epidermoid carcinoma cells growing as xenografts in the right hind leg of nude mice were used. Mice bearing 8-mm tumors were treated with C225 antibody at a dose of 1 mg given i.p. once, twice, or three times 3 days apart, 10 or 30 mg/kg docetaxel given i.v., and/or local tumor irradiation of 8 or 10 Gy single dose or fractionated irradiation consisting of 2 Gy daily for 5 days. When all three agents were combined, C225 was given 6 h before or 18 h after docetaxel, and radiation was given 24 h after docetaxel. The treatment end point was tumor growth delay. RESULTS: C225 enhanced the antitumor efficacy of docetaxel, local tumor irradiation, and docetaxel combined with radiation. The response of both MDA468 and A431 carcinomas was enhanced. The enhancement factors ranged from 1.19 to 8.52, the degree of the enhancement depending on experimental conditions such as administration of multiple vs. single dose C225 or single or fractionated irradiation. C225 given twice or 3 times was more effective than when administered as a single dose. The effect of C225 was more pronounced when combined with single than fractionated irradiation with or without docetaxel. The triple-agent therapy was more effective than a single agent or double combination therapies, expressed by both increased tumor growth delay and the rate of tumor cure. CONCLUSIONS: Our results show that C225 anti-EGFR antibody is a potent enhancer of tumor response to docetaxel or radiation as single agents, and to docetaxel when combined with radiation. Thus, these findings provide strong preclinical evidence in support of combination of anti-EGFR blockade with chemoradiotherapy.     

Addition of mitomycin C to cis-diamminedichloroplatinum(II)/hyperthermia/radiation therapy in the FSaIIC fibrosarcoma.

Hyperthermia (temperatures greater than or equal to 42 degrees C) is used clinically to improve the effectiveness of radiation therapy and, although therapeutic gains have been reported, efficacy is limited when tumours are large and/or radiation tolerance is reduced. In order to improve the utility of the hyperthermia/radiation combination we have tested the addition of cisplatin (CDDP) in the laboratory and in the clinic. Our clinical studies have shown that the CDDP/hyperthermia/radiation combination is tolerable and effective, but laboratory investigations demonstrated a relative lack of cytotoxicity in the hypoxic tumour subpopulation. In order to improve the effectiveness of the CDDP/hyperthermia/radiation combination against hypoxic cells we have evaluated the addition of mitomycin C, a hypoxic cell cytotoxic agent to this combination. Mitomycin C (5 mg/kg) i.p. produced a tumour growth delay (TGD) of about 5.3 days in the FSaIIC murine fibrosarcoma; hyperthermia (43 degrees C x 30 min) caused only about 1.4 day TGD and the combination of mitomycin C followed immediately by hyperthermia caused a TGD of about 8.6 days. CDDP (5 mg/kg) i.p. followed by hyperthermia and then 3 Gy on day 1 only of a 5 day x 3 Gy radiation protocol produced a TGD of about 25 days. With the addition of mitomycin C just before CDDP a TGD of about 44 days resulted. Whole tumour excision experiments demonstrated that mitomycin C was highly interactive with CDDP at 37 degrees C and was dose-modifying. When used with CDDP and hyperthermia, however, mitomycin C added little additional cytotoxicity. Hoechst 33342 dye diffusion-determined tumour subpopulation studies indicated a marked effect of the addition of mitomycin C in the dim (enriched in hypoxic cells) subpopulation and nearby equal cytotoxicity in both bright (enriched in euoxic cells) and dim cells resulted. These investigations suggest considerable potential therapeutic efficacy to the addition of mitomycin C to the CDDP/hyperthermia/radiation combination.     

Jasplakinolide: interaction with radiation and hyperthermia in human prostate carcinoma and Lewis lung carcinoma

Purpose: Human ovarian cancer cells were evaluated to determine whether combination treatment with mild hyperthermia and cisplatin could inhibit repair of sublethal radiation damage. Materials and methods: Human ovarian carcinoma cell lines A2780S (parental line) and A2780CP (cisplatin resistant variant) were used in this study. Cisplatin at concentrations of 1 or 3 μg/ml was given concomitantly with 1 h of heating at 40 °C either immediately before or after irradiation. Survival was determined using a colony-forming assay. Results: Neither mild hyperthermia nor cisplatin treatments alone affected sublethal damage repair. The combined treatment showed an effect in both cell lines and was treatment sequence-dependent. The effect was greater in the parental cell line. Conclusions: The data show that combined treatment of cisplatin and hyperthermia may have clinical efficacy at cisplatin concentrations and hyperthermia temperatures which by themselves have little to no effect. Received: 7 May 1997 / Accepted: 11 September 1997