Enhancement of semustine-induced cytotoxicity by chlorpromazine and caffeine in a human melanoma xenograft

Chlorpromazine (CPZ) and caffeine (CFN) enhance the cytotoxicity of nitrosoureas in conventional murine tumor systems, but this effect was not confirmed in a randomized clinical trial which compared the action of semustine (MeCCNU) against the combination of MeCCNU, CPZ, and CFN. Since differences in repair systems are known to exist between cells of human or murine origin, we have employed a human melanoma xenograft system to quantify the drug interaction. The enhancement in human melanoma cells was similar to that observed with conventional murine tumor systems. Alkaline elution studies and determination of radioactivity from labeled MeCCNU pointed to increased drug retention and fixation of DNA damage as the mechanism of enhancement. Although toxicity studies were limited to murine tissues, there was evidence of increased toxicity, especially if MeCCNU was combined with both CPZ and CFN. Thus, a true therapeutic synergism may not be present for the combination. Some explanations for the failure to detect such drug interaction in clinical trials and the relevance of advanced preclinical tumor systems are discussed.

Effect of Fluosol-DA/O2 on tumor-cell and bone-marrow cytotoxicity of nitrosoureas in mice bearing FSA-II fibrosarcoma

The perfluorochemical emulsion, Fluosol-DA, combined with carbogen breathing, potentiates the effects of radiation and a number of chemotherapeutic agents in several rodent tumors. The interaction of Fluosol-DA with drugs may be quite complex. In addition to increasing the oxygen supply in the tumor, Fluosol-DA may alter the pharmacokinetics of the drug and function as a drug delivery system. A series of 4 nitrosoureas of varying lipophilicity were administered as single doses intravenously (i.v.) to C3H/Be/FeJ mice bearing subcutaneous FSa-IIC fibrosarcomas. Doses of 40 mg/kg of CCNU, 15 mg/kg of BCNU, 20 mg/kg of MeCCNU and 15 mg/kg of chlorozoticin followed by 2 hr of breathing 95% oxygen produced tumor growth delays of 7.5, 4.0, 3.8 and 2.7 days, respectively. When the drug injection was followed immediately by 0.3 ml of Fluosol-DA and 2 hr of breathing 95% oxygen, the tumor growth delay produced by CCNU, BCNU, MeCCNU and chlorozoticin increased 2-fold, 10-fold, 4.5-fold and 3.5-fold, respectively. Administration of the drugs in Fluosol-DA followed by 2 hr of 95% oxygen breathing resulted in a 3.5-fold increase in tumor growth delay with CCNU, a 17-fold increase with BCNU, a 12.5-fold increase with MeCCNU and a 6-fold increase with chlorozoticin compared to drug and 95% oxygen breathing. These results are quantified in terms of cell survival by the tumor excision assay. Effects on the bone marrow from each treatment were measured using the granulocyte-monocyte colony-forming units (CFU-GM) assay. There was no correlation between the lipophilicity of the nitrosoureas tested and the tumor growth delay produced by each treatment.

Biphenotypic leukemia with unusual chromosomal translocation in a patient treated for melanoma

A patient in complete remission from malignant melanoma but with refractory anemia after nitrosourea treatment developed acute biphenotypic leukemia. This disease, progression was accompanied by expansion of a cytogenetically abnormal clone. At first cytogenetic analysis, 1 year post discontinuation of chemotherapy, only 25% of the metaphases examined were hypodiploid with monosomy 7. Six months later, all of the metaphases seen were 45,XY,-7. Six months before overt acute leukemia was diagnosed, an additional chromosome abnormality emerged, t(2;3)(q31;q27). Although the translocation was present in all metaphases examined, the patient progressed into an acute leukemia with two components: one TdT-positive, Ia-positive, and the other TdT-negative, Ia-positive, monocytoid antigen-positive. This mixed leukemia was identified by double fluorescence staining for intranuclear TdT and surface labeling with a monocyte-specific monoclonal antibody.

Emergence of nitrosourea resistant sublines of Lewis lung tumour following MeCCNU treatment in vivo

Several different drug retreatment protocols were employed to examine the emergence of resistance to MeCCNU in Lewis lung tumours. Previous studies suggested that although the majority of cells in untreated Lewis lung tumours were sensitive to MeCCNU, there was a very small proportion of resistant cells (approximately 0.001%) that limited "tumour cure' with that drug. If such cells were inherently drug resistant then it should be possible to derive highly resistant tumours by repeated drug treatment. In the first experiment tumours were treated with a single high dose of MeCCNU (35 or 40 mgkg-1) and on regrowth, transplanted into fresh mice and tested for drug sensitivity. Using both excision cell survival and growth delay endpoints, only approximately 25% of tumours were significantly resistant to the test dose, suggesting that many tumours resist the effects of the drug for reasons other than the presence of inherently drug resistant cells. One of the tumours (R4), that regrew after the initial treatment and appeared to be resistant to the test treatment, was retreated with a further 30 mgkg-1 MeCCNU and became more resistant. This line, designated R4/1, was cross-resistant to the other nitrosoureas, BCNU and CCNU, but not to cyclophosphamide, melphalan, cis-platinum or ionising radiation. The effect of treatment dose on the kinetics of MeCCNU resistance development was also studied in a retreatment regimen where the tumours were allowed to regrow and then transplanted into fresh hosts for the next treatment. Resistance developed more quickly at an intermediate dose of 15 mgkg-1 than at 7.5 mgkg-1 where the selective pressure was lower, or at 30 mgkg-1 where there was probably extinction of partially resistant cells. Resistance to MeCCNU developed even more quickly when tumours were retreated several times in the same host, although in a similar experiment with cyclophosphamide no resistance occurred.

Methyl-CCNU and methotrexate therapy in patients with advanced colorectal cancer after failure of 5-fluorouracil chemotherapy

Thirty-six patients with advanced colorectal cancer whose disease progressed during treatment with 5-fluorouracil (5-FU) chemotherapy were treated with methyl-CCNU and methotrexate. Five patients (14%) achieved a partial response (PR), three (8%) showed disease regression less than that required for a PR, and three (8%) showed evidence of stable disease. Twenty-five patients (69%) progressed on treatment. Tumor regression was seen only in patients with good performance status (ECOG 0.1). The median survival time of patients achieving a PR was 31 weeks. Those patients with stable disease or disease regression less than a PR had median survival times of 49 and 32 weeks, respectively. The comparable figure for those patients with disease progression was 17 weeks. Myelosuppression, principally in the form of leukopenia and thrombocytopenia, was common. Nausea and vomiting were universal with methyl-CCNU, and mucositis and diarrhea occurred commonly due to methotrexate. These results demonstrate the limited activity of chemotherapy in refractory colorectal cancer. They also reaffirm that poor pretreatment performance status should exclude patients from futile attempts at palliative therapy or phase II clinical trials, as these patients derive little or no benefit from them.

Combined 5-fluorouracil (5-FU) and radiation therapy following resection of locally advanced gastric carcinoma

Twenty-five patients with locally advanced but resectable adenocarcinoma of the stomach were given concomitant postoperative radiotherapy to the tumor bed and chemotherapy with 5-Fluorouracil (5-FU). Twenty-two of the patients had regional lymph node involvement and seven had residual tumor in the surgical margins. Radiotherapy was delivered to a total dose of 5,000 rads in 7 weeks with a two-week split. 5-FU was given daily the first 3 days of each treatment period and was then continued weekly for a minimum of 1 year. At a median follow-up time of 19 months, 11 patients have relapsed, two locally and nine distally, and all have died. Thirteen patients remain alive, all but one disease-free, for a median of 21 months from diagnosis. One additional patient died of unrelated causes, free of tumor. The actuarial median survival for the whole group stands at 33 months with a projected 5-year survival of 40%. Treatment has been well tolerated.

Cure rates and tumor resistance in cured mice after nitrosourea treatment of EMT6 ascites tumors

Single-dose BCNU or chlorozotocin (CLZ) treatment of EMT6 mammary carcinoma tumors of the BALB/c mouse has only a transient effect on tumor growth, after which tumors follow control growth patterns. To test the hypothesis that drug access to tumor cells might be a factor in cell killing, we adapted the EMT6/KY tumor to ascites form. Injection of 10(5) EMT6/KY cells i.p. kills BALB/c mice with a mean survival time of 13.0 +/- 1.0 days. We have surveyed several nitrosoureas for their effects on the EMT6/KY ascites tumor after intraperitoneal injection of the drugs. Cure rates and percent increase in life span were used as endpoints. Also, we tested for induced host tumor resistance (TR) in cured mice, by challenging survivors with live EMT6 cells. Highest cure rates were obtained for treatment on days 2, 3, or 4 after inocula of 10(5) cells: CLZ (10 mg/kg), 83.3%; cis-acid (20 mg/kg), 75%, and CCNU (30 mg/kg), 70%. Other nitrosoureas, i.e. BCNU, PCNU, GANU, STZN, FCNU, ACNU, MeCCNU, NSC-88104 produced lower cure rates. Cured mice surviving challenges of 10(6) EMT6 cells were considered TR. TR mice did not correlate with cure rates for the 3 nitrosoureas giving high cure rates. As percent of survivors, TR mice were (for day 3 treatment): FCNU, 100%, BCNU, 100.0% and CLZ, 50.0%. Thus, cure rates and TR seem to depend on the structure of the nitrosourea, but through different mechanisms.

Management of cancer in the elderly. Implications of the aging process

Cancer is one of the most serious illnesses of the elderly. Screening programs focusing on its early detection in this age-group are needed to allow maximum opportunity for cure. Also important is convincing the older patients who smoke that stopping is still worthwhile. Compared with younger patients, the elderly have more intercurrent medical illnesses and are more likely to suffer from financial difficulties and loss of family support. These factors must be considered when managing these patients. Although age-imposed compromises in treatment are often made, available data suggest that a priori dose reduction of chemotherapy on the basis of age alone is not indicated in patients with solid tumors. Prospective clinical trials are needed to further address the issue of responsiveness to chemotherapy as a function of age. Such trials should include assessment of physiologic age and quality of life.

O6-Alkylguanine-DNA alkyltransferase activity correlates with the therapeutic response of human rhabdomyosarcoma xenografts to 1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea

Immune-deprived female CBA/CaJ mice bearing xenografts of six different human rhabdomyosarcoma lines were treated with 1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea (MeCCNU). Tumor responses were compared with levels of O6-methylguanine-DNA methyltransferase activity because of evidence indicating that repair of DNA interstrand cross-link precursors, mediated by the transferase, may be an important determinant of MeCCNU cytotoxicity. Levels of methyltransferase in tumor extracts were measured by determining the loss of O6-methylguanine from 3H-labeled methylated DNA. Five of the six tumor lines examined showed either no response to MeCCNU or regrowth after an incomplete response. In each instance, the extent of tumor regression correlated with the level of O6-methylguanine-DNA methyltransferase activity in tumor extracts. The single highly drug sensitive line was totally devoid of the activity. These results suggest that O6-methylguanine-DNA methyltransferase levels in human tumor cells may be a clinically useful predictor of sensitivity to the chloroethylnitrosoureas.

Eastern Cooperative Oncology Group experience with chemotherapy for inoperable gallbladder and bile duct cancer

In a prospective randomized Eastern Cooperative Oncology Group (ECOG) study, 53 eligible and evaluable patients with advanced gallbladder carcinoma and 34 with advanced bile duct carcinoma were treated with oral 5-fluorouracil (5-FU) or with oral 5-FU plus streptozotocin (Stz) or oral 5-FU + Methyl-CCNU (MeCCNU). Severe toxicity occurred in 2 of 30 patients receiving 5-FU (7%), in 14 of 26 receiving 5-FU + Stz (54%), and in 12 of 31 receiving 5-FU + MeCCNU (39%). Five of 53 patients with gallbladder carcinoma (2/18 [11%] on 5-FU, 2/16 [12%] on 5-FU + Stz, and 1/19 [5%] on 5-FU + MeCCNU) had objective response to treatment. There was no significant difference between treatments with respect to response or survival. Three of 34 patients with bile duct cancer (1/12 [8%] on 5-FU, 0/10 on 5-FU + Stz, and 2/12 on 5-FU + MeCCNU) had objective response to treatment. There was no significant difference between treatments with respect to response or survival. Patients with prior chemotherapy were randomized between MeCCNU alone and Stz alone. Among such patients, only 1 of 17 patients who had prior chemotherapy with other agents responded to MeCCNU alone, and none of 14 patients responded to Stz alone.

Primary liver cancer. An Eastern Cooperative Oncology Group Trial

One hundred ninety-two patients with unresectable primary liver cancer studied by members of the Eastern Cooperative Oncology Group (ECOG) were evaluable in a prospectively randomized clinical trial. Patient discriminants such as performance status were carefully evaluated to assess their influence on prognosis and to evaluate the importance of patient status on response and survival. Patients who were totally bedridden or with signs of overt liver failure were not entered on study. The median survival time for all evaluable previously untreated patients was 17 weeks (19 weeks for North American and European, and 10 weeks for South African black patients). Among the South African patients, however, there was a significantly larger proportion with an initially poor performance status. Prognostic variables (performance status, jaundice, and reduced appetite) dominate any differences among the treatments studied. Among North American and European patients on intravenous (IV) 5-fluorouracil (5-FU) + Methyl-CCNU (MeCCNU) + Adriamycin (ADM, doxorubicin), the 19% response rate is offset by 63% with severe toxicity and a median survival time of only 17 weeks, making this treatment unacceptable clinically. The median survival time of North American and European patients treated with IV 5-FU +/- MeCCNU was 28 weeks in contrast to a median survival time of 12 weeks with ADM (P less than or equal to 0.01). EST 2273 was the ECOG study of patients with primary liver cancer. The results of the first part of the trial were published in 1978. This report updates those findings and reports the results of patients entered subsequently on the second part of that study after it was amended in 1979. With more than 300 evaluable patients in EST 2273, this duet of studies is the largest ever conducted in patients with primary liver cancer, and draws a new baseline from which to measure the disease and its response to treatment.

Eastern Cooperative Oncology Group experience with chemotherapy for inoperable gallbladder and bile duct cancer

In a prospective randomized Eastern Cooperative Oncology Group (ECOG) study, 53 eligible and evaluable patients with advanced gallbladder carcinoma and 34 with advanced bile duct carcinoma were treated with oral 5-fluorouracil (5-FU) or with oral 5-FU plus streptozotocin (Stz) or oral 5-FU + Methyl-CCNU (MeCCNU). Severe toxicity occurred in 2 of 30 patients receiving 5-FU (7%), in 14 of 26 receiving 5-FU + Stz (54%), and in 12 of 31 receiving 5-FU + MeCCNU (39%). Five of 53 patients with gallbladder carcinoma (2/18 [11%] on 5-FU, 2/16 [12%] on 5-FU + Stz, and 1/19 [5%] on 5-FU + MeCCNU) had objective response to treatment. There was no significant difference between treatments with respect to response or survival. Three of 34 patients with bile duct cancer (1/12 [8%] on 5-FU, 0/10 on 5-FU + Stz, and 2/12 on 5-FU + MeCCNU) had objective response to treatment. There was no significant difference between treatments with respect to response or survival. Patients with prior chemotherapy were randomized between MeCCNU alone and Stz alone. Among such patients, only 1 of 17 patients who had prior chemotherapy with other agents responded to MeCCNU alone, and none of 14 patients responded to Stz alone.

Chemotherapy of advanced colorectal carcinoma: fluorouracil alone vs. two drug combinations using fluorouracil, hydroxyurea, semustine, dacarbazine, razoxane, and mitomycin. A phase III trial by the Eastern Cooperative Oncology Group (EST: 1278)

Patients with advanced colorectal cancer and no prior chemotherapy were randomized to six treatment regimens: A) fluorouracil (FU) alone; B) FU + hydroxyurea (HU); C) semustine (SE) + dacarbazine (DA); D) FU + HU alternating with SE + DA; E) SE + razoxane (RA); F) mitomycin (MI) + DA. There were no significant treatment differences with respect to response, which ranged from 9-23% (overall 32/207 or 15%) or median survival duration, which ranged from 17 weeks to 32 weeks. Patients treated with FU or FU + HU experienced substantially less toxicity than those on the other treatment arms.

Identification of a subpopulation of MeCCNU resistant cells in previously untreated Lewis lung tumours

A variety of experimental endpoints including excision cell survival, lung colony curability, tumour regrowth delay and i.m. tumour curability following MeCCNU alone and combined with gamma-radiation, were used to define the MeCCNU cell survival curve down to "tumour cure" level in previously untreated i.m. Lewis lung tumours. The survival curve was found to be biphasic, the tumour cells being markedly resistant to MeCCNU at high doses of the drug. Below 10 mg kg-1 the survival curve was exponential through the origin with a D10 of approximately 2 mg kg-1, while above 15 mg kg-1 the D10 was approximately 25 mg kg-1. From linear extrapolation of the terminal part of the cell survival curve to zero drug dose, it appeared that about 1 in 10(5) (or 0.001%) of tumour cells were resistant to MeCCNU.

Induced and inherent resistance to alkylating agents in human small-cell bronchial carcinoma xenografts

Inherent and induced resistance was investigated in human small-cell lung cancer xenografts. Specimens from three patients were established in immune suppressed mice; the sensitivity of the xenografts to cyclophosphamide, MeCCNU and melphalan was determined using the growth delay end-point. Clinical chemosensitivity data were available in two cases and inherent differences in sensitivity were noted both in the xenografts and clinically. Radioactively labelled melphalan uptake studies were performed with these two xenografts. A number of different strategies to induce resistance were explored. Only one method proved to be successful and in only one of the xenografts; this was with cyclophosphamide. The induced resistant line was characterised in terms of the time course of its production, the degree of induced resistance, the growth rate, the cross-resistance pattern and stability of the phenotype; the possibility of altered antigenicity was also examined.

Randomized trial of chlorozotocin, neocarzinostatin, or methyl-CCNU in patients with malignant melanoma

One hundred twenty-two patients with disseminated malignant melanoma were randomized using an unbalanced randomization to receive chlorozotocin, neocarzinostatin, or MeCCNU. Of the 114 evaluable patients, 46 received chlorozotocin, 47 received neocarzinostatin, and 21 received MeCCNU. The response rates to these three drugs were 9%, 4%, and 14% respectively. Median survival times were 4.2, 3.4, and 5.8 months respectively. Toxicity was acceptable with all three agents. Chlorozotocin and neocarzinostatin do not appear to offer any improved response rates over MeCCNU for patients with disseminated malignant melanoma.

Studies on drug resistance in a human melanoma xenograft system

Alkylating agents and their functional analogues belong to the most useful antineoplastic drugs in the treatment of disseminated malignant melanoma. In conjunction with an open clinical phase II trial evaluating the combination of cisplatin and ifosfamide, 17 melanoma xenograft lines were established from patients often refractory to dacarbazine (DTIC). These xenograft lines were exposed to cisplatin, dacarbazine, dibromodulcitol, ifosfamide, methyl-CCNU, mitomycin C, and malonato-diaminocyclohexane-platinum II (PHM) at the respective LD 10/30 doses. Growth delay values less than 2 corresponded in 26/27 instances with progressive disease, whereas values greater than 2 corresponded in only 10/13 instances with achievement of a no-change status or a partial remission of the donor patient's disease. Among the panel of DNA-damaging agents tested, cross-resistance was incomplete. Some xenograft lines revealed unique chemosensitivity patterns in contrast to a uniform pattern of drug resistance in others (pleiotropic or multidrug resistance). The data confirm independently of results obtained in the phase II study that the combination of cisplatin and ifosfamide is effective against malignant melanoma refractory to dacarbazine. Suboptimal drug exposure, repeated up to 21 transplant generations, was employed to induce secondary resistance to either dacarbazine, melphalan or methyl-CCNU in a melanoma xenograft line originally quite sensitive to drug treatment. When the resistant sublines were exposed to the other agents, only partial cross-resistance was observed. Tumour volume responses to treatment with dacarbazine correlated with persisting DNA damage assayed 24 h after in vivo drug exposure in a sensitive line and the absence of such lesions in a resistant line.

cis-4-[[[(2-Chloroethyl)nitrosoamino]carbonyl]methylamino] cyclohexanecarboxylic acid, a nitrosourea with latent activity against an experimental solid tumor

cis-4-[[[(2-Chloroethyl)nitrosoamino]carbonyl]methylamino] cyclohexanecarboxylic acid (N-Me-cis-CCCNU) was synthesized in five steps from cis-4-aminocyclohexanecarboxylic acid via an N-tosylated intermediate. N-Me-cis-CCCNU, which is incapable of the facile decomposition that characterizes the clinically useful nitrosoureas, effected a significant cure rate of both early and established murine Lewis lung carcinoma, even though its in vitro half-life was approximately 5.5 times that of the unmethylated parent compound. This is the first observation of latent activity of a nitrosourea against an experimental solid tumor.

Therapeutic evaluation of five nitrosoureas in a human melanoma xenograft system

The development of nitrosoureas has switched from more lipophilic derivatives to congeners with higher water-solubility, since this property was presumably associated with a decrease in myelosuppression. We have compared the therapeutic efficacy of clinically well-known lipophilic nitrosoureas BCNU, CCNU, and MeCCNU with the recently introduced water-soluble nitrosoureas chlorozotocin (CZT) and hydroxyethyl-CNU (HeCNU), using a human melanoma xenograft system. There were considerable differences in tumor-inhibitory activity, with HeCNU ranking first and CZT last, and the rank order was similar for drug-induced lethality or bone marrow damage (in terms of reduced cellularity or macromolecular DNA damage). When the doses are expressed as percentages of the corresponding LD10/30 values, CZT ranks last and HeCNU low among conventional nitrosoureas. We conclude that water-solubility is not associated with reduced myelosuppression and that other guidelines will have to be adopted for rational development of nitrosoureas.

In vivo drug sensitivity assay of clonogenic human melanoma cells and correlation with treatment outcome

In vitro tests of tumor cell drug sensitivity have been suggested as a means of selecting more appropriate clinical strategies against human cancer and improving preclinical drug development. The lack of biotransformation in these in vitro assays precludes the meaningful assessment of several major chemotherapeutic agents, including dacarbazine and cyclophosphamide. In vivo drug exposure of tumor cells in agar diffusion chambers placed in mice offers a possible solution to problems of drug biotransformation and pharmacokinetics. We have prospectively used this system as an assay for sensitivity of clonogenic human melanoma cells. Tumor cells were tested fresh, cryopreserved, and/or cultured in vitro before or after clinical use of dacarbazine, semustine, and mitolactol in 41 patient-drug combinations in which a clinical correlation could be made. Tumor cell drug sensitivity in the assay using fresh or cryopreserved tumor cells was highly correlated with clinical response and resistance with clinical nonresponse. Cultured melanoma cells exhibited enhanced plating efficiency in comparison to both fresh and cryopreserved cells of the same tumor. Cultured cells also showed increased drug sensitivity which did not correlate with drug sensitivity of the same fresh or cryopreserved tumor or with clinical response. Tumor cell drug sensitivity assays carried out in vivo provide a possible basis for preclinical evaluation of drugs which are unsuitable for in vitro testing.

Ineffectiveness of chemotherapy in patients with metastatic ependymoma of the cauda equina

Six cases of intraspinal ependymoma metastasizing outside the central nervous system have been reported. This report documents a seventh case. This patient received multiple courses of combination and single-agent chemotherapy without evidence of tumor regression. All seven patients had four things in common: early onset of disease, numerous operations, massive local recurrence at the time distant metastases were noted, and a long time period from diagnosis to death.