Five-chlorodeoxycytidine, a tumor-selective enzyme-driven radiosensitizer, effectively controls five advanced human tumors in nude mice

PURPOSE

The study's goals were as follows: (1) to extend our past findings with rodent tumors to human tumors in nude mice, (2) to determine if the drug protocol could be simplified so that only CldC and one modulator, tetrahydrouridine (H4U), would be sufficient to obtain efficacy, (3) to determine the levels of deoxycytidine kinase and dCMP deaminase in human tumors, compared to adjacent normal tissue, and (4) to determine the effect of CldC on normal tissue radiation damage to the cervical spinal cord of nude mice.

METHODS AND MATERIALS

The five human tumors used were as follows: prostate tumors, PC-3 and H-1579; glioblastoma, SF-295; breast tumor, GI-101; and lung tumor, H-165. The duration of treatment was 3-5 weeks, with drugs administered on Days 1-4 and radiation on Days 3-5 of each week. The biomodulators of CldC were N-(Phosphonacetyl)-L-aspartate (PALA), an inhibitor of aspartyl transcarbamoylase, 5-fluorodeoxycytidine (FdC), resulting in tumor-directed inhibition of thymidylate synthetase, and H4U, an inhibitor of cytidine deaminase. The total dose of focused irradiation of the tumors was usually 45 Gy in 12 fractions.

RESULTS

Marked radiosensitization was obtained with CldC and the three modulators. The average days in tumor regrowth delay for X-ray compared to drugs plus X-ray, respectively, were: PC-3 prostate, 42-97; H-1579 prostate, 29-115; glioblastoma, 5-51; breast, 50-80; lung, 32-123. Comparative studies with PC-3 and H-1579 using CldC coadministered with H4U, showed that both PALA and FdC are dispensable, and the protocol can be simplified with equal and possibly heightened efficacy. For example, PC-3 with X-ray and (1) no drugs, (2) CldC plus the three modulators, (3) a high dose of CldC, and (4) escalating doses of CldC resulted in 0/10, 3/9, 5/10, and 6/9 cures, respectively. The tumor regrowth delay data followed a similar pattern. After treating mice only 11/2 weeks with CldC + H4U, 92% of the PC-3 tumor cells were found to possess CldU in their DNA. The great majority of head-and-neck tumors from patient material had markedly higher levels of dC kinase and dCMP deaminase than found in adjacent normal tissue. Physiologic and histologic studies showed that CldC + H4U combined with X-ray, focused on the cervical spinal cord, did not result in damage to that tissue.

CONCLUSIONS

5-CldC coadministered with only H4U is an effective radiosensitizer of human tumors. Ninety-two percent of PC-3 tumor cells have been shown to take up ClUra derived from CldC in their DNA after only 11/2 weeks and 2 weeks of bolus i.p. injections. Enzymatic alterations that make tumors successful have been exploited for a therapeutic advantage. The great electronegativity, coupled with the relatively small Van der Waal radius of the Cl atom, may result in CldC's possessing the dual advantageous properties of FdC on one hand and BrdU and IdU on the other hand. These advantages include autoenhancing the incorporation of CldUTP into DNA by not only overrunning but also inhibiting the formation of competing TTP pools in tumors. A clinical trial is about to begin, with head-and-neck tumors as a first target of CldC radiosensitization.

Long-term survival in 11,661 patients with multivessel coronary artery disease in the era of stenting: a report from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Investigators

BACKGROUND

Studies of survival of patients with multivessel coronary artery disease (MVD) in the prestent era suggested that outcomes after coronary artery bypass surgery (CABG) are similar to those after percutaneous coronary intervention (PCI) in subsets of coronary severity. The purpose of this study of the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) was to examine the association between treatment and survival up to 5 years in patients with MVD enrolled from 1995 through 1998.

METHODS AND RESULTS

Data on patient characteristics were obtained at the time of the initial coronary angiography. Survival was determined through data linkage to the provincial Bureau of Vital Statistics. Risk-adjusted hazard ratios were calculated to compare different treatments. In the 11,661 patients with MVD, CABG was the initial therapy in 3782, PCI in 3540, and medical therapy in 4339. Cumulative 5-year survival was 91.4% with CABG, 91.9% with PCI, and 82.9% with medical therapy (P <.001). Hazard ratios were CABG: medical 0.53 (95% confidence interval [CI] 0.46-0.71), PCI: medical 0.65 (95% CI 0.56-0.74), and CABG: PCI 0.81 (95% CI 0.68-0.96). Analysis across coronary severity groups revealed a benefit of CABG compared with PCI only in the group with severe left main CAD: 0.30 (95% CI 0.17-0.54).

CONCLUSIONS

In a multicenter clinical setting, MVD patients treated with revascularization have significantly higher 5-year survival rate than do those treated medically. Risk-adjusted comparison reveals PCI treatment to be associated with long-term survival similar to treatment with CABG in all coronary severity subgroups except the group with severe left main coronary artery disease. Patient selection factors are likely to be contributing to these findings.

School peer relationships of 'minority' children in Scotland

This paper examines selected issues arising from two studies in mainstream education of two minority groupings of children in Scotland-those with serious medical conditions and refugee children-completed in 1997 and 1999, respectively. It draws on first-person accounts of children, parents and teachers and focuses on school-based peer relationships, including friendships. Many of the described peer experiences were unhappy or mixed, only a minority were positive. The paper relates the research and its findings to current social and educational policy contexts and to theories on peer relationships, friendship and rejection. It challenges the problematizing of groups or individuals with minority experiences and school staff's acceptance of inevitable difficulty in these children's peer relationships. It hypothesizes that ways of developing all children's peer relationships need to be addressed in schools if the well-being of children who may be socially vulnerable is to be improved.

Cyclophosphamide-based, seven-drug hybrid and low-dose involved field radiation for the treatment of childhood and adolescent Hodgkin disease

PURPOSE

The outlook for children and adolescents with Hodgkin disease (HD) is excellent with combined modality therapy. However, the long-term toxicities of multiagent therapy and radiation therapy remain of concern for these patients with curable disease. In an attempt to reduce long-term toxicities while preserving excellent cure rates, we developed a combined-modality protocol using a modified seven-drug hybrid and low-dose (2,000 cGy) involved field radiation therapy (RT). The hybrid used cumulative doses of alkylating agents and anthracyclines that were lower than those used in previous four-drug regimens and substituted a less leukemogenic agent, cyclophosphamide, for nitrogen mustard.

PATIENTS AND METHODS

From 1991 through 1994 a cyclophosphamide, vincristine, procarbazine, and prednisone/adriamycin, bleomycin, and vinblastine hybrid was used to treat 29 patients with HD. Median age was 12 years (range 6-16 yrs). Patients who were postpubertal with early stage disease as determined by surgical staging were excluded. Treatment consisted of four cycles of therapy for stages I and IIA, six cycles for stages IIB and III, and eight cycles for stage IV. Twenty-two patients also received low-dose RT to areas of bulky disease.

RESULTS

Twenty-eight patients (97%) had a complete response to chemotherapy. Five patients experienced relapse; two died from disease 27 and 29 months after initial diagnosis; three received additional therapy and are alive with no evidence of disease. Follow-up for all other patients is a median of 56 months (range 24-78 mos) from cessation of therapy and all have remained disease-free. At 5 years follow-up, actuarial disease-free survival is 82%, and the overall survival is 93%. There have been no clinically significant cardiac or pulmonary toxicities and no secondary malignancies.

CONCLUSIONS

This therapy has resulted in 5-year overall survival and disease-free survival rates similar to regimens using higher doses of alkylating agents, anthracyclines, and radiation. Longer follow-up will be necessary to fully evaluate disease-free survival, organ damage, and quality of life.