Assessment of in vitro drug sensitivity of human tumor cells using [3H]thymidine incorporation in a modified human tumor stem cell assay.

We have developed a method for performing in vitro drug testing on primary human tumor explants which is a variant of the human tumor stem cell assay (HTSCA) described previously by Salmon et al. (N. Engl. J. Med. 298: 1321, 1978). The method utilizes a cell-containing liquid top layer and a soft-agar bottom layer. Tumor growth is measured by [3H]thymidine incorporation into material precipitable by 5% trichloroacetate. Results show linear correlations with number of cells plated and with a number of colonies per plate measured using the HTSCA, when cell aliquots from one sample are used. In vitro drug sensitivity, as determined by inhibition of [3H]thymidine incorporation, correlates with HTSCA results in 54 of 61 determinations (89%). Of 22 experiments in which drug sensitivity curves were compared, 21 (95%) were similar in both systems. The [3H]thymidine method yields results more quickly (5 days after samples are plated) and with smaller variances than those measurements obtained using the HTSCA. Normal human skin muscle, lung, and colon tissue and a human fibroblast cell line do not incorporate significant amounts of [3H]thymidine into trichloroacetic acid-precipitable material. Thus, normal cell components plated in tumor samples do not interfere with assay results. Standard scintillation counting is used; optical counting, either visual or automated, is not required. Therefore, the measurement of in vitro drug sensitivity by inhibition of incorporation of radiolabeled precursors deserves further evaluation as a predictor of in vitro response.

Influence of tetrahydrouridine on the pharmacokinetics of intrathecally administered 1-beta-D-arabinofuranosylcytosine.

Tetrahydrouridine (THU), a potent inhibitor of cytidine deaminase, has been shown to increase the antitumor activity of 1-beta-D-arabinofuranosylcytosine (ara-C) both in vitro and in vivo. In initial studies, which examined the cerebrospinal fluid (CSF) pharmacokinetics of intrathecally (i.t.) administered THU, the drug was found to be slowly cleared from the CSF with alpha and beta half-lives of 1 and 8 hr, respectively. In subsequent experiments, both i.v. pretreatment with THU and concomitant i.t. injection of THU were found to retard the disappearance of i.t. ara-C from the CSF, although the effect of i.t. THU was more profound. ara-C given alone was cleared from CSF with alpha and beta half-lives of 27.5 +/- 6.7 and 115.6 +/- 0.4 (S.D.) min, respectively. Pretreatment with i.v. THU resulted in alpha and beta half-lives of 10.4 +/- 1.5 and 85.7 +/- 11.1, respectively, whereas concomitant administration of i.t. THU resulted in a single half-life of 96 +/- 0.7. The mean calculated clearance rates for ara-C alone, ara-C plus i.v. THU, and ara-C plus i.t. THU were 7.5, 6.2, and 4.2 ml/hr, respectively. This effect appeared to be primarily due to THU inhibition of ara-C deamination, since a decrease in formation of 1-beta-D-arabinofuranosyluracil in the CSF was observed when ara-C was given in the presence of THU (either i.t. or i.v.). No acute neurotoxicity was noted after administration of either i.t. THU alone or i.t. THU with ara-C. The ability of THU to alter CSF ara-C pharmacokinetics may have potential therapeutic value.

Controlled clinical trials of nutritional intervention as an adjunct to chemotherapy, with a comment on nutrition and drug resistance.

Nutritional intervention in the cancer patient [e.g., total parenteral nutrition (TPN)] might improve durable survival because of increased tolerance to aggressive tumor therapy. To determine whether this assumption is correct, 42 patients with diffuse histiocytic lymphoma were induced with prednisone, high-dose methotrexate, Adriamycin, cyclophosphamide, and VP-16 (ProMACE). Nitrogen mustard-vincristine-procarbazine-prednisone (MOPP) consolidation was then used, followed by late intensification with ProMACE. Patients were selected randomly to receive adjuvant TPN or a standard diet during ProMACE-MOPP treatment. While TPN patients had a greater median weight gain than did control patients, lean body mass and degree of myelosuppression did not improved as a consequence of TPN. There was no significant difference in tumor response or survival between TPN and control patients, whether or not the patients were initially malnourished. In a second trial, 32 young patients with metastatic or other poor-prognosis sarcomas were randomly allocated to receive TP or a standard diet as an adjunct to one very intensive course of combination chemotherapy or chemotherapy plus total body irradiation; autologous marrow transplantation was used with gain than did controls but remained in a negative nitrogen balance. Response rates and median durable survival did not differ between the two groups. In both trials, the maximum nutritional support permitted by currently available technology was offered. Thus, the limiting factor may not be nutritional status but rather the intrinsic biology of the tumors and the limitations of their response to current therapy. In in vitro studies of the possible influence of nutrition on cancer treatment, we have compared sublines of P388 murine leukemia cells which are sensitive or resistant to Adriamycin. The difference in drug sensitivity correlated with differences in lipid composition, with more intracellular lipid, and with greater membrane rigidity in the resistant cells. Resistant cells have a relatively poor transport of drug into the cell; moreover, intracellular Adriamycin is sequestered in lipid depots away from DNA. These results suggest one possible relationship between nutritional phenomena and drug sensitivity.

L-asparaginase pharmacokinetics and asparagine levels in cerebrospinal fluid of rhesus monkeys and humans.

L-Asparaginase has been widely used for the treatment of acute lymphoblastic leukemia. Therapeutic and toxic effects in the central nervous system have been noted with systemic treatment. In order to better define the relationship between L-asparaginase administration and cerebrospinal fluid (CSF) asparagine levels, L-asparaginase and asparagine were measured in the CSF of rhesus monkeys following intrathecal and i.v. administration. Following intrathecal injection, the enzyme activity of Escherichia coli L-asparaginase in the CSF demonstrated a more rapid terminal half-life than did that of 111In-labeled diethylenetriaminepentaacetic acid, a marker of CSF bulk flow [4 +/- 0.7 (S.D.) hr versus 5.8 +/- 0.2 hr]. Intrathecal injection of E. coli asparaginase resulted in complete depletion of CSF asparagine for at least 5 days. A similar period of CSF asparagine depletion was observed following i.v. administration of L-asparaginase. Similar results were found in seven patients undergoing systemic L-asparaginase therapy. The minimal plasma level of L-asparaginase necessary to deplete CSF asparagine in both species was 0.1 IU/ml. Two other enzymes, Erwinia L-asparaginase and succinylated Acinetobacter glutaminase-asparaginase, were cleared from the CSF at the same rate as bulk flow. These data indicate that systemic L-asparaginase therapy may be a feasible means of treating central nervous system involvement in patients with acute lymphoblastic leukemia and that there is no therapeutic advantage to using intrathecal L-asparaginase.

Active transport of methotrexate from cerebrospinal fluid in humans.

The cerebrospinal fluid (CSF) efflux kinetics of methotrexate (MTX) were studied in three patients with indwelling Ommaya reservoirs. A small dose of MTX was injected intraventricularly several hr after the start of a high-dose continuous i.v. infusion of MTX. In all patients, the CSF antifolate concentration returned to the preinjection level before the end of the i.v. infusion. This result indicated that the efflux of MTX from CSF in humans is independent of plasma drug concentrations. Efflux kinetics were further characterized in one patient. Serially obtained CSF samples after intraventricular injections demonstrated a biphasic disappearance curve with alpha- and beta-phase half-disappearance times of 1.7 and 6.6 hr, respectively. Prolongation of the beta-phase half-time was associated with oral acetazolamide medication and with increased intracranial pressure, indicating that inhibition of CSF production slows MTX clearance. CSF MTX concentration, however, declined more rapidly than that of simultaneously administered diethylenetriaminepentaacetic acid, an extracellular marker substance excreted by bulk flow, indicating that bulk flow excretion alone is insufficient to account for MTX efflux from human CSF. Evidence that there is an active transport component was provided by probenecid pretreatment which also prolonged the CSF MTX half-life. These findings suggest that both passive and active mechanisms govern MTX efflux from the CSF in humans and that they can be inhibited by acetazolamide and probenecid, respectively.

Phase I study of 2'-deoxycoformycin in acute lymphoblastic leukemia.

2'-Deoxycoformycin (2'-dCF), a tight-binding inhibitor of adenosine deaminase, was administered to 26 pediatric patients with acute lymphoblastic leukemia in a Phase I study. Doses ranged from 0.25 to 1.0 mg/kg given i.v. for 3 consecutive days. Common toxicity included nausea, vomiting, diarrhea, hepatocellular enzyme elevations, and conjunctivitis. Lymphopenia occurred in all patients. The most serious adverse effects were acute tubular necrosis and central nervous system toxicity, which appeared to be dose related. In addition, two patients given the 0.75-mg/kg dose developed severe hepatic toxicity, although this could not be ascribed definitively to 2'-dCF. Antitumor activity was observed in eight patients, two of whom experienced a complete remission. Inhibition of lymphoblast adenosine deaminase activity was noted in the majority of cases and was observed at all doses. Antileukemic activity occurred at doses of 2'-dCF which were not associated with limiting toxicities. These results suggest that 2'-dCF is active against acute lymphoblastic leukemia and that a starting dose of 0.5 mg/kg/day be utilized in Phase II studies.

Protein-associated DNA breaks in cells treated with adriamycin or ellipticine.

The effect of intercalating agents on mammalian DNA in vivo was examined by the technique of alkaline elution. Adriamycin and ellipticine were found to produce large numbers of single-strand breaks. These breaks appeared to be intimately associated with protein to the extent that enzymatic deproteinization of the DNA was necessary to reveal the breaks. The frequency of breaks and cross-links increased with concentration and time of exposure to the drugs. These data suggest that DNA single-strand scission may be a feature common to intercalators. The association with a cellular protein is previously undescribed and suggests possible mechanisms for the strand scission.

Treatment of sarcomas of the chest wall using intensive combined modality therapy.

As part of two sequential protocols using intensive combined modality treatment in pediatric and adolescent sarcomas, 31 consecutive patients with primary chest wall tumors were treated between November 1977 and March 1986. This group included 13 patients with peripheral neuroepithelioma (Askin's tumor), 11 patients with Ewing's sarcoma, 3 patients with rhabdomyosarcoma, and 4 patients with undifferentiated sarcomas. Following complete work-up, 17 patients presented with localized disease and 14 patients presented with metastases. Patients received intensive combined modality treatment with combination chemotherapy (vincristine, cyclophosphamide, Adriamycin, +/- actinomycin-D and DTIC) and high-dose conventionally fractionated radiation therapy to the primary (55-60 Gy) and non-pulmonary metastases (45-50 Gy). Radiation techniques used for the primary chest wall tumor varied with the clinical presentation. Patients achieving a complete response received either low-dose fractionated TBI (1.5 Gy/0.15 Gy fx/5 weeks) or high-dose TBI (8 Gy/4 Gy fx/2 days) and an intensive cycle of chemotherapy followed by autologous bone marrow transplantation. Twenty-five of 31 patients were judged to have a complete response (including 1 patient with complete resection). With minimum follow-up of 6 months and median follow-up of 36 months from completion of treatment, 14 patients remain disease-free with 2 additional patients alive in second remission after relapse. Patients with localized disease at presentation have improved disease-free survival and overall survival compared to patients with metastases at presentation. All 17 localized patients achieved a CR and 11 are NED compared to 8 of 14 metastatic patients achieving a CR and only 3 are NED. There have been 5 loco-regional recurrences with 3 "in-field" failures and 2 failures in the regional pleura. There were no treatment-related deaths and no clinically significant cases of pneumonitis. To date, 2 patients have significant treatment related morbidity, including 1 patient with scoliosis requiring surgery and 1 patient with acute leukemia developing 42 months after the start of therapy (presently in remission). We conclude that this intensive combined modality therapy results in a high CR rate and good local control with acceptable morbidity. Patients with metastatic disease at presentation remain a therapeutic challenge.

Electrolytic degradation of DNA fluorochromes during flow cytometric measurement of electronic cell volume.

Changes in flow cytometric measurement of DNA content can result from electrolytic chemical degradation of mithramycin, ethidium bromide, and propidium iodide during simultaneous measurement of electronic cell volume. Bench electrolysis also degrades these fluorochromes without changing the quantum yields, even when they are complexed to DNA. In the flow cytometer, electrolytic production of chlorine at the anode is the probable cause of this degradation, since exposure of these fluorochromes to chlorine gas produces the same effect. It is therefore advisable to measure the DNA content distribution alone before simultaneously measuring the DNA content and the electronic cell volume. If unavoidable effects on the DNA distribution are present, narrow forward-angle light scatter should be used as the cell size indicator during dual parameter measurements. Modifying instrument design by reversing electrode polarity might eliminate this problem.

DNA crosslinking and cell survival in human lymphoid cells treated with 8-methoxypsoralen and long wavelength ultraviolet radiation.

8-Methoxypsoralen (8-MOP) when irradiated with long wavelength ultraviolet radiation (UV-A) inhibits DNA synthesis in lymphocytes in vitro and in vivo. 8-MOP binds reversibly to DNA in the dark; when exposed to UV-A, covalent monoadducts and cross-links are formed with the DNA. The present study correlates the cytotoxic effects of 8-MOP plus UV-A with DNA crosslinking. E-B virus transformed human lymphoblastoid cells were suspended in a colorless salt solution containing 8-MOP and exposed to UV-A from fluorescent lamps filtered to remove radiation below 320 nm (22.5 J/m2-sec). Cells were then returned to complete medium and assayed for survival (by daily counts of viable cells and by cloning in microtiter wells) and for DNA crosslinking by alkaline elution. 8-MOP alone or UV-A alone resulted in minimal to no alterations in survival or in DNA crosslinking. DNA crosslinking was found to be linearly dependent on 8-MOP concentration (in the range of 0.01-1.0 microgram/ml) for 3 different UV-A doses (3000-15 000 J/m2). The surviving fraction declined exponentially as a function of the relative number of DNA crosslinks. These results suggest that the cytotoxic effects of photoactivated 8-MOP in human lymphoblastoid cells may depend on DNA interstrand crosslinks.

Phase II study of 5-azacytidine in sarcomas of bone.

Eight patients with osteogenic sarcoma and seven patients with Ewing's sarcoma, all with advanced metastatic disease refractory to conventional therapy, were treated with 5-azacytidine (NSC-102816) intravenously at a dosage of 150 mg/m2 in three divided doses daily X 5 days. The courses were repeated q 4 weeks and the dosage was escalated to 200 mg/m2/day, as tolerated. Fourteen patients were evaluable for response. Major toxicities wee hematologic and gastrointestinal. 5-azacytidine had no demonstrable antitumor activity.

Influence of prognostic factors on survival in Ewing's sarcoma.

We have analyzed the survival data for 117 patients with Ewing's sarcoma treated at the National Cancer Institute since 1964. Treatment consisted of local irradiation to the primary site and a series of increasingly intensive systemic chemotherapy regimens. Four protocols were used with varying numbers of patients in each treatment group. When survival results were compared by treatment group, an overall difference in favor of the most recent treatment regimens was demonstrated (P less than 0.03). When results were evaluated by treatment group according to the site of primary disease, a significant difference was found only for patients who presented with primary lesions of the central axis and without metastases (P less than 0.001). However, we noted a statistically significant correlation of survival with 1) site of primary disease (P less than 0.001), 2) serum lactate dehydrogenase (LDH) level at presentation (P less than 0.0001), and 3) metastatic status at presentation (P less than 0.0001), irrespective of treatment protocol. When the results were reassessed after adjustment for these factors, no significant difference in survival remained. We concluded that further studies, in which stratification for site of primary disease and LDH levels would be used, are necessary to clarify the role of intensive adjuvant chemotherapy in Ewing's sarcoma.

Subsequent cancer in patients with Ewing's sarcoma.

Among 31 long-term survivors of Ewing's sarcoma, two patients developed second primary cancers, compared to an expected number of 0.03 (relative risk = 72; 95% confidence limit = 8-259). One patient had renal medullary neuroblastoma, which is not known to be related to Ewing's tumor or its therapy. The second patient had a bone fibrosarcoma, arising at the primary tumor site, which was thought to be radiation-induced. The risk of radiation-induced bone sarcomas was lower, although not significantly so, than in a recently reported series of Ewing's tumor. These two reports suggest that patients with Ewing's sarcoma have a tendency to develop radiogenic sarcomas following primary megavoltage radiation therapy. The lowest radiation dose consistent with local tumor eradication should be employed to minimize the risk of subsequent radiogenic cancer.

Probenecid inhibition of methotrexate cytotoxicity in mouse L1210 leukemia cells.

The effect of probenecid on methotrexate cytotoxicity has been measured using mouse L1210 leukemia cells in vitro. Cytotoxic effects were measured using a soft agar cloning technique. Cell exposure to varying concentrations of methotrexate at fixed concentrations of probenecid resulted in increased cell survival when compared with exposure to methotrexate alone. Cell exposure to a fixed concentration of methotrexate and varying concentrations of probenecid showed this effect to be dependent on the concentration of probenecid. Intracellular methotrexate concentrations were unchanged by the presence of probenecid. However, there was an effect of probenecid on progression of cells through the cell cycle which would tend to decrease the number of cells susceptible to the cytotoxic effects of methotrexate.

Azaserine, DON, and azotomycin: three diazo analogs of L-glutamine with clinical antitumor activity.

A review of the clinical data on azaserine, DON, and azotomycin reveals that these agents have limited but definite antitumor activity. All three drugs are analogs of L-glutamine and contain a diazo group. They have been studied as single agents in a wide variety of human malignancies and have also been included in trials using combination chemotherapy. Most of these studies were performed early in the history of clinical trials and, therefore, the method of reporting results and the evaluation criteria were quite different from those in use today. A renewed interest in these agents has been triggered by the remarkable activity of DON and azotomycin against human tumor lines implanted into nude mice. On the basis of this activity and the clinical data we have compiled, we feel that new clinical trials with these agents are warranted.

Probenecid inhibition of methotrexate-cerebrospinal fluid pharmacokinetics in dogs.

Cerebrospinal fluid (CSF) and plasma concentrations of methotrexate (MTX) were followed in dogs for 72 hours after intracisternal injection of MTX with and without probenecid pretreatment. CSF levels declined as a biexponential function of time. Probenecid pretreatment of the animals prolonged the second phase half-disappearance time of MTX from 5.20 +/- 0.89 to 7.086 +/- 0.23 hours (mean +/- SD). The peak mean plasma concentration of MTX was lower in the presence of probenecid. Also, the rate of decline of plasma MTX concentrations was slower after treatment with probenecid, with mean half-disappearance times of 7.60 +/- 0.77 and 11.32 +/- 1.08 hours. These CSF and plasma data support the proposal that probenecid inhibits the transfer of MTX from CSF to blood.

Determination of prognostic factors and their influence on therapeutic results in patients with Ewing's sarcoma.

We have analyzed the results of treatment of 117 patients with Ewing's sarcoma admitted to the National Cancer Institute since 1964. All patients received local irradiation to the primary site and a series of progressively more intensive systemic chemotherapy regimens using drugs known to be active as single agents in this disease. Four protocols were employed with varying numbers of patients in each treatment group. Initially, there appeared to be a difference among treatment groups with regard to disease-free survival (overall P = .06), with the later regimens having more favorable outcomes. We then undertook a statistical analysis of the influence of five pretreatment variables--age, sex, site of primary disease, serum lactic acid dehydrogenase (LDH), and metastatic status--on disease-free survival. Of these five factors, important indicators of favorable prognosis for the entire group (and for each of the treatment subgroups) were a distal site of primary disease, normal serum lactic acid dehydrogenase (LDH) level at presentation, and the absence of metastatic disease at the time of presentation. When we examined treatment results with respect to these prognostic factors, we found that the subgroups treated with the more agressive regimens contained higher proportions of patients with favorable prognostic factors. After adjustment for differences in composition of treatment groups with respect to prognostic factors, the apparent difference in disease-free survival vanished (P = .62). These results indicate that in the case of Ewing's sarcoma, prognostic factors must be carefully considered in the design of treatment protocols and the subsequent analysis of end results.

Chondrosarcoma of the larynx after radiation treatment for vocal cord cancer.

The case of a 57-year-old man with chondrosarcoma of the laryngeal cartilage is presented, occurring 16 years after radiation treatment for squamous cell carcinoma of the right true vocal cord. Chondrosarcoma of the larynx is an uncommon tumor. The location, grade, and time elapsed from initial treatment make it probably that this patient's chondrosarcoma is associated with his prior radiation treatment. However, it is a rare occurrence, this being the second case reported in the literature.