A comparative study of Ro 03-8799: racemic mixture and enantiomers

The maximum single dose of the 2-nitroimidazole hypoxic cell radiosensitiser Ro 03-8799 is limited to 1 g/m2 by the occurrence of a well characterised acute syndrome of sweating, nausea and mental changes. In an attempt to increase the tolerable dose, the clinical toxicity of the racemic mixture was compared with that of the R- and S-enantiomers of Ro 03-8799. Twelve patients received escalating alternate doses of racemic mixture and R- or S-enantiomer, the dose levels being 0.25 g/m2, 0.5 g/m2, 0.75 g/m2 and 1.0 g/m2. Careful monitoring of the acute syndrome failed to demonstrate any consistent differences between racemic mixture and either enantiomer. This would suggest that the toxicity is not mediated via any specific central nervous system receptor. It is concluded that separation of Ro 03-8799 into its enantiomers will not enable a clinically useful increase in dosage.

Effect of misonidazole dose on survival in patients with stage IIIB-IVA squamous cell carcinoma of the uterine cervix: an RTOG randomized trial

Between August 1980 and November 1984, 120 patients with FIGO Stage IIIB or IVA squamous cell carcinoma of the uterine cervix were randomized to receive radiation therapy (RT) (46 Gy pelvis + 10 Gy parametrial boost) followed by intracavitary or external boost to the primary +/- misonidazole (MISO) (400 mg/M2 2-4 hours prior to RT daily, maximum 12 gm/M2). The median at 24-28 hr misonidazole plasma level was 20 micrograms/ml 2-6 hr and 3.5 micrograms/ml. Approximately 60% of the patients on RT + MISO received 100% of expected total Misonidazole dose; peripheral neurologic toxicity was reported for nine patients receiving misonidazole (8 with mild and 1 with moderate paresthesia or pain). Time-dependent regression analyses found that actual cumulative misonidazole dose was not related to duration of survival from start of treatment (p = 0.5). MISO dose expressed as a percent of expected dose was marginally related to increased survival measured from 14 weeks on on study (p = 0.1). No improvement in survival was observed with the addition of misonidazole to RT (64% of the patients on RT alone were alive at 18 months versus 54% of those on RT + MISO).

Use of ornidazole in fractionated radiotherapy: dose tolerance, serum and tumour tissue concentration

Sensitizing and neurotoxic effect of ornidazole, was tested in a double-blind randomized study in patients with carcinoma of the cervix and larynx. Ornidazole or placebo were given orally, two times weekly, for 3 weeks. Dose was 2.5 g/m2 for each administration. Total dose given was 15 g/m2. Radiation therapy was given 3 h after the drug administration. Ornidazole was well tolerated in the majority of the patients. No neurotoxic side effects, such as peripheral neuropathy or convulsion, were observed with a total dose of up to 30 g. Dizziness, somnolence and nausea were the prominent acute side effects, seen mostly (70%) in women. In the placebo group this rate was 17% (p less than 0.01). No important side effect was observed in men receiving ornidazole. Serum concentration of ornidazole reached the maximum level in 2-4 h after oral administration and ranged (23 patients) from 65.1 to 139.8 micrograms/ml. Mean half-life was 15.6 +/- 2.8 h. Peak concentration in tumour tissue was achieved 1-3 h after the administration, ranging from 13.0 to 78.0 micrograms/g. Tumour concentration of ornidazole ranged from 14 to 93% of the serum concentration at the time of irradiation.

Radiotherapy and cis-diammine dichloroplatinum (II) as a combined treatment modality for inoperable non-small cell lung cancer: a dose finding study

A dose finding study was carried out to establish the dose of cis-diammine dichloroplatinum (II), cDDP, that can be combined with high dose radiotherapy routinely in patients with inoperable non-small cell lung cancer. The patients were irradiated over a period of 2 weeks, 5 fractions a week, followed by a rest period of 14 days. Thereafter a second course of 2 weeks was given; a total dose of 55 Gy was achieved. The weekly cDDP administration in a 3 hour infusion with pre- and posthydration preceded the first day irradiation. Twenty patients were evaluable for acute toxicity. The dose limiting factor appeared to be severe nausea and vomiting, which was not responsive to anti-emetic therapy at a cDDP level of 35 mg/m2. No renal or significant hematological side effects were observed. Complete response was seen in 10 patients, using X rays and CT scans; this was confirmed by bronchoscopy with biopsies in 9 patients. Partial remission was scored in 7 patients and no change in 4 patients. cDDP as a radiosensitizer will be further studied at a dose level of 30 mg/m2 a week or 6 mg/m2 a day in a prospective, randomized EORTC Phase II study.

Distinctive eruption characterized by linear supravenous papules and erythroderma following broxuridine (bromodeoxyuridine) therapy and radiotherapy

A distinctive cutaneous eruption occurred in two patients with central nervous system tumors who were treated with broxuridine (bromodeoxyuridine) and radiotherapy. Findings included the initial appearance of papular lesions within skin directly overlying acral superficial veins and the later development of a more generalized eruption eventuating into exfoliative erythroderma.

Chemical sensitizers for hypoxic cells: a decade of experience in clinical radiotherapy

The clinical work with chemical agents to restore the radiosensitivity of hypoxic cells began in 1973 with metronidazole, misonidazole was first given in 1974. The results so far recorded of the clinical trials with misonidazole have been generally disappointing. Only in 5 of 32 studies analyzed have significant benefits been shown to suggest real advantage with the use of misonidazole. Hypoxic cells must exist in all human tumours presenting for treatment and it is, however, probable that the oxygen effect is an important one at all dose fractionation regimes employed in radiotherapy but, after conventional fractionated radiotherapy, hypoxia may be a reason for failure in only a proportion of cases. The most important factor underlying the failure of misonidazole to achieve useful advantage is undoubtedly the low radiosensitizing concentrations achievable with the permitted dose of this neurotoxic drug. New drugs are under development and some have different dose-limiting toxicity. Those showing promise at this time are the Stanford compound, SR-2508, which is being extensively studied in the United States and the Roche compound, Ro 03-8799, which is being studied in the United Kingdom. It is possible that the greatest sensitization with the greatest tolerance will be achieved by a combination of drugs.

Clinical trials with cyclophosphamide and misonidazole combination for maintaining treatment after radiation therapy of lung carcinoma

Fifteen patients with inoperable non oat cell lung carcinoma, who had already been treated with telecobalt therapy in the mediastinum-hilar region, were treated with continuing therapy with misonidazole (MISO) and cyclophosphamide (Cy). MISO was administered in single doses of 1000 mg/m2 and 500 mg/m2, orally. Cy was administered in single doses of 500 mg/m2 and 250 mg/m2, i.v. This treatment was given every 4 weeks. All patients (15/15) suffered from hyporexia, nausea and vomiting within 48 hours from administration; furthermore, 2 patients had hemoragic cystitis, 2 had peripheral neurotoxicity, 3 had fever, and 2 had serious nervous depression. Leukopenia occurred in all patients immediately after drug administration, although it was not present in any patient by the time of the next administration. This clinical trial was concluded in December 1981. The follow-up at 18 months shows 7/15 cases of relapse (3 patients dead and 1 patient alive with recurrence, 2 patients dead and 1 patient alive with metastasis without recurrence). Eight of 15 patients are alive with progression of disease from 8 to 18 months.

Identification of bromodeoxyuridine in malignant and normal cells following therapy: relationship to complications

During a clinical Phase I study of bromodeoxyuridine (BUdR) as a radiation sensitizer we identified the normal and malignant cells that incorporated the BUdR. BUdR was infused for up to 14 days and the in vivo incorporation of BUdR into DNA was assessed using an immunohistochemical technique and a monoclonal antibody directed against BUdR. BUdR was identified in 50% of breast cancer cells and 10% of cells in a malignant melanoma. BUdR was also found in the basal layer of the normal epidermis and in 50% of cells in the marrow. The incorporation of BUdR into cells in the epidermis and marrow may produce the phototoxicity and myelosuppression observed in patients treated with BUdR. Sequential biopsies from a breast cancer taken prior to and following radiotherapy suggested that cells that incorporated BUdR may have been selectively killed by the radiation. The immunohistochemical technique used to identify BUdR appeared to be useful for studies of in vivo and in vitro cell proliferation.

[Pharmacokinetics and the effects of metronidazole during its use as a radiosensitizer]

During gamma-beam therapy (40-60 Gy) a study was made of the content of metronidazole (MZ) in the blood of 20 patients with oral mucosa cancer and 12 patients with esophageal cancer depending on a mode of its administration. A MZ effect on liver and renal function was studied. MZ was administered to the patients with cancer of both sites on the first 3 days of radiation therapy 3 h before an enlarged fraction of 4 Gy, estimated at 145 mg per 1 kg body mass (8-10 g) per os or via a gastrostoma and 15 g in rectal administration. In the patients with oral mucosa cancer after the administration of MZ per os its level which was sufficient for radiosensitization, was achieved after 2 h and remained for subsequent 4 h with maximum accumulation of 262 +/- 22 micrograms/ml in the blood serum 3-4 h after administration. In 24 h there remained 84 +/- 9 micrograms/ml of MZ in the blood (32% of its maximum level). In the patients with esophageal cancer after MZ administration via the gastrostoma, the nature and time course of drug accumulation in the blood was identical, however accumulation maximum was lower and reached 219 +/- 25 micrograms/ml. In the patients with esophageal cancer after MZ rectal administration, its level in the blood was 118 micrograms/ml only and did not achieve a therapeutically effective level. In repeated administration of MZ per os or via the gastrostoma its accumulation by 25-30% was observed. MZ caused a transient increase in the permeability of the cell membranes of the liver and the suppression of its protein-forming function. It is assumed that the lowering of MZ repeated dose by 20% will cause a decrease in the drug accumulation in the body and the degree of a toxic effect with maintaining its therapeutically effective level in the blood and tumor.

Cutaneous complications of chemotherapeutic agents

Increasing numbers of chemotherapeutic agents are being used to treat patients with cancer and various immunologically mediated and inflammatory disorders. Many of the drugs used have distinctive cutaneous side effects that range from relatively common ones, such as alopecia, stomatitis, and hyperpigmentation, to more unusual ones, such as radiation enhancement and recall phenomena, photosensitivity and hypersensitivity reactions, and phlebitis or chemical cellulitis. In addition, there are some rare complications such as diffuse sclerosis of the hands and feet, Raynaud's phenomenon, sterile folliculitis, and flushing reactions. By being aware of which drug may have caused a particular cutaneous reaction, dermatologists will be able to contribute to the care of patients with complex problems in a meaningful way.

Photocarcinogenesis, skin cancer, and aging

Nonmelanoma skin cancers, like most malignancies, increase in incidence with increasing age. However, in general they are not due to the aging process but are primarily due to solar radiation. Clinically, squamous cell carcinomas and basal cell epitheliomas are the most common cancers that occur in the Caucasian population in the United States. The role of radiation from the sun was suggested by a number of astute clinical observations reported around 1900 and subsequently has been established by epidemiologic and experimental studies. Action spectrum evaluations indicate that the ultraviolet B (UVB) rays are the most carcinogenic. However, recent studies indicate that the UVA rays can augment the cancer-producing effects of UVB rays. Other physical stimuli, including heat and wind, can also accelerate UVB carcinogenesis. Chemicals such as the polycyclic hydrocarbons, the nitrosoureas, and nitrogen mustard have an additive carcinogenic effect with UVB radiation. Also, some chemicals such as croton oil, the phorbol ester--TPA, and all-trans-retinoic (RA) acid can promote UVB-initiated carcinogenesis. RA can also inhibit UVB-induced cancer formation. The role of the immune status has received a great deal of attention. Both in experimental and clinical situations, nonspecific immune suppression results in increased cancer formation. Also, recent studies indicate that a specific T cell suppressor population can be induced in experimental animals with UVB which will inhibit rejection of tumors produced by UVB radiation. Finally, damage to DNA by UVB radiation is well established. Studies with the genetic disease xeroderma pigmentosum support the concept that such damage, if not repaired, will lead to cancer formation. It also has been suggested that unrepaired damage to deoxyribonucleic (DNA) and other macromolecules is at least in part responsible for the aging process in general.

Radical irradiation and misonidazole in the treatment of T2 grade III and T3 bladder cancer

The results of 2 pilot studies using a new radiation fractionation schedule plus misonidazole (MISO) in the radical radiotherapy of T2 Grade III and T3 carcinoma of the bladder are presented. Forty Gy in 20 daily fractions of 2 Gy was administered to the whole pelvis over 4 weeks followed by 12 Gy in 2 weekly fractions of 6 Gy. These last 2 doses were given after MISO administration. In an initial pilot study (Pilot Study I) MISO was administered orally only. The first two patients received MISO at a dose of 4.5g/m2 orally with each radiation fraction, after which the dose was reduced to 3.0g/m2 because of drug toxicity. In the second pilot study (Pilot Study II) MISO was administered orally at a dose of 3.0g/m2 and intravesically at a dose of 1.0g to 22 patients. The complete response rate at cystoscopy at 6 months in the latter group of patients is 73%, which is significantly better than that of 43% obtained in a retrospective study of historical controls. There have been no late radiation complications in any of the patients nor any MISO toxicity apart from nausea in the patients receiving 3.0g/m2 orally with or without the intravesical MISO.

A pilot study with ethyl bis (2,2-dimethyl-1-aziridinyl) phosphinate (AB-163) and radiation therapy

Ethyl bis (2,2 dimethyl-1-aziridinyl) phosphinate (AB-163), a TEPA analogue, was used with radiation therapy in treating 18 patients with advanced malignancies. There were 12 patients with esophageal carcinoma; 3 with adenocarcinomas of the gastrointestinal tract; one, squamous carcinoma of the cervix; and one, adenocarcinoma of the ovary. One hundred mg/M2 AB-163 was given by rapid i.v. drip one half-hour before conventional radiation therapy. The majority of patients received 10 combined treatments. Three of those with squamous cell carcinomas (two in the esophagus and one in the cervix) remained disease-free for more than 2 years. One with liver metastasis and unresectable carcinoma of the stomach survived for 9 months. The drug causes side effects mainly involving the central nervous system and gastrointestinal tract. Drug-related myelosuppression has not been observed. The mode of action is speculated to be a result of active intermediate hydrolysis products which appear capable of phosphorylating X ray induced DNA strand damage. However, much additional investigation is required, both in vitro and clinically, before its efficacy and safety can be demonstrated.

Initial pharmacology and toxicology of intravenous desmethylmisonidazole

Since January 1981, 52 patients have entered the Radiation Therapy Oncology Group Phase I trial with intravenous (i.v.) desmethylmisonidazole (DMM). DMM is less lipophilic than misonidazole (MISO) and theoretically will be less neurotoxic due to lower penetration into neural tissue and more rapid elimination. The drug is administered intravenously to achieve the maximum drug concentration in tumor for a given dose. The protocol slowly escalates the total dose of drug administered. At this time the planned dose on the three week schedule is 1g/m2 five times per week to a total of 15g/m2, and on the seven week schedule is 1.25g/m2 twice weekly to a total dose of 17.5g/m2. The preliminary plasma pharmacokinetic data demonstrates high peak plasma levels within five minutes of the end of the drug infusion. Compared to MISO the percent of DMM excreted in the urine is increased, 63% vs 10%, and the elimination half-life is decreased: DMM, i.v. 5.3h; MISO, i.v. 9.3h; MISO, oral 10 to 13h. Neurotoxicity has been observed in approximately 30% of patients given a cumulative dose of greater than 11g/m2. This is in comparison to a 50% incidence in the RTOG Phase I study with oral MISO at doses of 12g/m2. There is not sufficient data to evaluate the relationship between neurotoxicity and drug exposure. Further patient accrual on this study is required to better define the properties of DMM.

Mechanisms of hypoxic cell radiosensitization and the development of new sensitizers

Some of the mechanisms by which drugs can potentiate the radiation response of tumors and cells in culture are discussed. Emphasis is placed on the action of nitroaromatic and heterocyclic compounds as hypoxic cell radiosensitizers, and some potential successors to misonidazole (MISO) are described. These include desmethylmisonidazole and SR 2508, selected because of their low toxicity in experimental systems. Groups of compounds, more efficient sensitizers than would be predicted from electron affinity correlations, have been examined and the use of Ro-03-8799 or RSU 1047 is proposed. Finally, ortho-substituted nitroimidazoles and electron-affinic compounds with alkylating groups are described. The latter group, in particular, holds promise for the development of compounds much superior to MISO.

Neurotoxic radiosensitizers and head and neck cancer patients--how many will benefit?

The causes for the exclusion of patients from a Phase I dose tolerance study of metronidazole as a hypoxic cell sensitizing agent in patients receiving radiation therapy for head and neck cancer have been reviewed. One hundred and fifty nine consecutive patients were assessed between October 1979 and December 1980 according to eligibility criteria decided upon prior to the study. Only 26 (23%) of 111 patients treated with radical radiation therapy entered the Phase I study. The major reasons for exclusion were a history of prior nervous system abnormality, age over 70, and refusal by some patients to participate in the study. The criteria used for patient selection for studies of hypoxic cell sensitizers (and other investigational agents) must be known so that data from each study can be assessed appropriately before being extrapolated to the general patient population. Clinical trials should be designed to take into account factors that might influence patient entry.