Gliadel wafer in initial surgery for malignant glioma: long-term follow-up of a multicenter controlled trial.

OBJECTIVE: Adjuvant systemic chemotherapy increases survival of primary malignant glioma patients beyond 12-18 months. The only interstitial chemotherapy treatment approved for malignant glioma is Gliadel wafer containing carmustine (BCNU) placed in the resection cavity at surgery. Analysis of a large trial by Westphal and colleagues (n = 240) showed a 29% risk reduction (P = 0.03) in the BCNU wafer-treated group over the course of the 30-month trial. Long-term follow-up of these patients was undertaken to determine the survival benefit at 2 and 3 years. METHODS: Survival proportions for the placebo and treatment groups over the 56-month study were estimated by the Kaplan-Meier method. Multiple-regression analyses using the Cox proportional hazards model included prognostic factors of age, KPS, and tumor type. A secondary analysis was conducted for 207 GBM patients. RESULTS: Of the 59 patients available for long-term follow-up, 11 were alive at 56 months: 9 had received BCNU wafers and 2 had received placebo wafers. Median survival of patients treated with BCNU wafers was 13.8 months vs 11.6 months in placebo-treated patients (P = 0.017) with a hazard ratio of 0.73 (P = 0.018), representing a 27% significant risk reduction. This survival advantage was maintained at 1, 2, and 3 years and was statistically significant (P = 0.01) at 3 years. Two of 207 GBM patients remained alive at the end of the follow-up period, both in the BCNU wafer-treated group. CONCLUSION: Malignant glioma patients treated with BCNU wafers at the time of initial surgery in combination with radiation therapy demonstrated a survival advantage at 2 and 3 years follow-up compared with placebo.

Candida lambica polyarthritis in a patient with chronic alcoholism.

We describe a patient with an indolent polyarthritis over a period of several years caused by Candida lambica probably acquired from a contaminated wound. C. lambica has not been previously reported to cause infectious arthritis. Hematogenous spread was manifest by 4 separate sites of involvement. Chronic alcoholism was the only apparent risk factor for dissemination. The infection seems to be environmentally acquired.

Basis of observed resistance of L1210 leukemia in mice: methotrexate, 6-thioguanine, 6-methylmercaptopurine riboside, 6-mercaptopurine, 5-fluorouracil, and 1-beta-D-arabinofuranosylcytosine administered in different combinations.

Schmid et al. (Cancer Treat. Rep., 60: 23-27, 1976) reported rapid emergence of resistance of L1210 leukemia cells in mice to two schedules of six antimetabolites and much slower development of resistance to a third schedule. Such rapid development of resistance to six drugs presents a striking puzzle, and one whose solution gives some insights into the basis for general emergence of drug resistance. Our approach was to examine the consequences of applying these drugs singly or in pairs and, from the results, to infer interactions in six-drug combinations. 6-Thioguanine (TG) and 6-mercaptopurine are the key drugs since, as shown by Schmid et al., resistance of leukemic cells appeared to six-drug combinations at the same time as did resistance to the purine analogs; sensitivity to the other drugs remained. We demonstrated that cells which emerged were resistant to both of the purine analogs, owing to a deficiency of the activating enzyme hypoxanthine-guanine phosphoribosyltransferase. TG resistance arose in the presence of TG because of an overgrowth of TG-resistance mutants that were present as one cell in 10(4) in the original L1210 population. L1210 cultures were prepared free of TG-resistant mutants. With these cells, TG administered shortly after inoculation was very effective in delaying their death. The cells that finally grew out were still TG sensitive. Simultaneous treatment with all the drugs greatly delayed appearance of TG resistance in vivo and in vitro. Methotrexate alone was responsible for this result, owing to its ability preferentially to kill TG-resistant cells. The other three drugs were not effective in delaying TG resistance. Methotrexate was effective only if it was added daily; one large injection was ineffective. Therefore, TG and methotrexate added daily for 6 days (simultaneous schedule) was the most effective drug regimen tested.

Growth arrest states of RNA virus- and chemically transformed mouse cells.

Moloney virus- and benzo(a)pyrene-transformed cells, like the mouse BALB/c 3T3 cell line from which they are derived, arrest with a G1 DNA content in serum-deficient medium. The arrested cells are stimulated to proliferate by readdition of serum. The stimulated Moloney virus-transformed cells show identical kinetics of entry into S phase and also synthesize the same marker proteins as do growth-stimulated quiescent (G0) BALB/c 3T3 cells. In contrast, the benzo(a)pyrene-transformed cells enter S phase about 2 hr earlier and show a lower level of marker protein synthesis. Studies with cycloheximide indicate that protein synthesis is required for all three lines to resume DNA synthesis. Thus, it appears that transformed tumorigenic cells can have kinetic and biochemical growth properties very similar to those of their nontumorigenic parental cells.

Quiescent cells but not cycling cells exhibit enhanced actin synthesis before they synthesize DNA.

Major proteins synthesized by Swiss 3T3 cells at different stages of the cell cycle have been analyzed using double isotope labeling and one-dimensional SDS-polyacrylamide slab gels. The synthesis of actin was previously shown to be markedly enhanced a few hours after quiescent cells initiated growth following addition of serum. In contrast, the synthesis of actin remained at a constant rate, similar to that in quiescent cells, relative to synthesis of other proteins during the entire cell cycle. We conclude that enhanced actin synthesis is a process specific for the G0 to S transit, and may serve as a marker event during this interval. In contrast, three other proteins (90,000, 57,000, and 33,000 daltons) were synthesized throughout the cell cycle at higher rates than in G0 cells, and thus, are markers characteristic of cells traversing the cell cycle. A transient increase, such as seen for actin synthesis, by cells emerging from quiescence, may represent a process that these cells must perform before they can enter the G1 portion of the cell cycle. A transient event such as this need not be a periodic event that occurs during each cycle.

Synthesis of labile, serum-dependent protein in early G1 controls animal cell growth.

We present a model to account for several major observations on growth control of animal cells in culture. This model is tested by means of kinetic experiments which show that exponentially growing animal cells whose ability to synthesize total protein has been inhibited with cycloheximide (by up to 70%) grow at rates approximately proportional to their rates of protein synthesis. However, virtually the entire elongation of the cell cycle occurs in the part of the G(1) phase that depends on a high concentration of serum in the medium. This part of the cycle has earlier been suggested to lie prior to the restriction point-i.e., the point beyond the main regulatory processes of G(1). The remainder of the cycle, from restriction point to mitosis, is markedly insensitive to these concentrations of cycloheximide as well as to growth regulation. We quantitatively account for the specific lengthening of that part of the cycle involved in growth regulation by assuming that cells must accumulate a specific protein in a critical amount before they can proceed beyond the restriction point. The lability of this protein (half-life about 2 hr) makes its accumulation unusually sensitive to inhibition of total protein synthesis by cycloheximide. Its production appears to depend on growth factors provided by serum. The model can also account for greater variations of G(1) durations as the growth of cell populations is made slower. It also predicts two sorts of quiescence: one of cells slowly traversing G(1), in slightly suboptimal conditions; the other of cells that enter G(0) under inadequate conditions. Transformation of different sorts could create cells with altered variables for initiation, synthesis, or inactivation of the regulatory protein or could altogether eliminate the need for the protein.

Changes in the synthesis of actin and other cell proteins after stimulation of serum-arrested cells.

The synthesis of both cytoplasmic and nuclear proteins has been studied as quiescent, serum-deprived Swiss mouse 3T3 cells are stimulated to transit the cell cycle. In serum-arrested cells a 200,000 dalton cytoplasmic protein and a 51,000 dalton nuclear protein were found to be preferentially synthesized. In serum-stimulated cells the first major protein whose synthesis was seen to increase had a molecular mass of 42,000 daltons. This protein also showed the greatest change in synthesis during the transit from G0 to S phase. Its synthesis rose to a maximum 4--6 hr after stimulation and then declined as cells entered S phase. The protein was present in both nuclear and cytoplasmic extracts. It was identified as actin on the basis of its mobility on sodium dodecyl sulfate and isoelectric focusing polyacrylamide gels. Other proteins synthesized preferentially by stimulated cells had molecular masses of 57,000 daltons (cytoplasmic), 33,000 daltons (cytoplasmic and nuclear), and 15,000 daltons (nuclear). The synthesis of the 57,000 and 33,000 dalton proteins increased gradually after stimulation and remained high during S phase. The 15,000 dalton proteins began to be synthesized as cells entered S phase. The preferential synthesis of these proteins provides biochemical markers for the transition from quiescence to proliferation.

Growth control of normal and transformed cells.

Both serum factors and protein synthesis are required for normal cell growth. Swiss 3T3 cells require the serum growth factors insulin and EGF (epidermal growth factor) during the initial part of the G1 period, until they pass a restriction point about 2 h before the initiation of DNA synthesis. Concentrations of cycloheximide that inhibit protein synthesis by as much as 70% dramatically lengthen the cell cycle before the restriction point, while the cell cycle after the restriction point remains nearly constant. These results are consistent with a model in which labile proteins are required for transit of cells past the serum-sensitive restriction point. The relation of these findings to the growth control of transformed cells is discussed.

Synthesis of a liver enzyme in hybrid cells.

Rat hepatoma cells were fused with cells of an established mouse lymphoma line, with normal diploid mouse macrophages, lymphocytes and fibroblasts and with normal diploid rat macrophages and lymphocytes. The liver-specific enzyme tyrosine aminotransferase was produced by almost all the hybrid cells, but usually at a lower level than in the parental hepatoma cells. Most of the hybrids also showed increased levels of this enzyme after exposure to dexamethasone. In the rat x mouse hybrids, the electrophoretic mobility of the enzyme indicated that only the rat hepatoma enzyme was produced. The findings are difficult to explain in terms of simple models involving a single diffusible repressor or activator of tyrosine aminotransferase synthesis.