Clinical practice guidelines for the care and treatment of breast cancer: 15. Treatment for women with stage III or locally advanced breast cancer

OBJECTIVE

To define the optimal treatment for women with stage III or locally advanced breast cancer (LABC).

EVIDENCE

Systematic review of English-language literature retrieved from MEDLINE (1984 to June 2002) and CANCERLIT (1983 to June 2002). A nonsystematic review of the literature was continued through December 2003.

RECOMMENDATIONS

The management of LABC requires a combined modality treatment approach involving surgery, radiotherapy and systemic therapy. Systemic therapy: chemotherapy. Operable tumours. Patients with operable stage IIIA disease should be offered chemotherapy. They should receive adjuvant chemotherapy following surgery, or primary chemotherapy followed by locoregional management. Chemotherapy should contain an anthracycline. Acceptable regimens are 6 cycles of FAC, CAF, CEF or FEC. Taxanes are under intense investigation. Inoperable tumours. Patients with stage IIIB or IIIC disease, including those with inflammatory breast cancer and those with isolated ipsilateral internal mammary or supraclavicular lymph-node involvement, should be treated with primary anthracycline-based chemotherapy. Acceptable chemotherapy regimens are FAC, CAF, CEF or FEC. Taxanes are under intense investigation. Patients with stage IIIB or IIIC disease who respond to primary chemotherapy should be treated until the response plateaus or to a maximum of 6 cycles (minimum 4 cycles). Patients with stage IIIB disease should then undergo definitive surgery and irradiation. The locoregional management of patients with stage IIIC disease who respond to chemotherapy should be individualized. In patients with stage IIIB or IIIC disease who achieve maximum response with fewer than 6 cycles, further adjuvant chemotherapy can be given following surgery and irradiation. Patients whose tumours do not respond to primary chemotherapy can be treated with taxane chemotherapy or can proceed directly to irradiation followed by modified radical mastectomy, if feasible. Systemic therapy: hormonal therapy. Operable and inoperable tumours. Tamoxifen for 5 years should be recommended to pre- and postmenopausal women whose tumours are hormone responsive. Locoregional management. Operable tumours. Patients with stage IIIA disease should receive both modified radical mastectomy (MRM) and locoregional radiotherapy if feasible. They may be managed with MRM followed by chemotherapy and locoregional radiotherapy, or chemotherapy first followed by MRM and locoregional radiotherapy. Breast-conserving surgery is currently not a standard approach. Locoregional radiotherapy should be delivered to the chest wall and to the supraclavicular and axillary nodes. The role of internal mammary irradiation is unclear. Inoperable tumours. Patients with stage IIIB disease who respond to chemotherapy should receive surgery plus locoregional radiotherapy. The locoregional management of patients with stage IIIC disease who respond to chemotherapy is unclear and should be individualized. Patients whose disease remains inoperable following chemotherapy should receive locoregional radiotherapy with subsequent surgery, if feasible.

VALIDATION

The authors' original text was revised by members of the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer. Subsequently, feedback was provided by 9 oncologists from across Canada. The final document was approved by the steering committee.

SPONSOR

The Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer was convened by Health Canada. Completion date: December 2003.

Increased use of adjuvant regional radiotherapy for node-positive breast cancer in British Columbia

This study was to determine if the use of regional radiotherapy (RT) changed in British Columbia after publication of new randomized trial data in 1997. Women with pathologic T1-3N1, nonmetastatic breast cancer treated with a mastectomy or breast-conserving surgery (BCS) were included. The use of regional RT was compared in two cohorts: cohort 1, July 1, 1995-June 30, 1997 (n = 834); and cohort 2, July 1, 1998-June 30, 2000 (n = 1072). All p-values were two-sided. Adjuvant systemic therapy was given to 96% and 95% of women in cohorts 1 and 2, respectively. Forty-five percent of cohort 1 and 48% of cohort 2 had BCS. Regional RT was received by 44% of cohort 1 and 66% of cohort 2 (p < 0.001). Eighty-eight percent and 90% of women with four or more positive nodes in cohorts 1 and 2 received regional RT, respectively. For women in cohorts 1 and 2 with one to three positive nodes, regional RT use increased from 32% to 54% after mastectomy, and from 23% to 59% after BCS, respectively (p < 0.001 for both). Publication of randomized trials and a coordinated guideline implementation process in British Columbia was associated with a significant increase in the use of regional RT in women with one to three positive nodes.

Prognostic significance of the number of axillary lymph nodes removed in patients with node-negative breast cancer

PURPOSE

The objective of the study was to evaluate the association between the number of lymph nodes removed at axillary dissection and recurrence and survival for patients with node-negative invasive breast cancer.

PATIENTS AND METHODS

Subjects were 2,278 women with pathologically node-negative invasive breast cancer, diagnosed from 1989 to 1993 in British Columbia, Canada. Women aged > or = 90 years, with pure in-situ, bilateral invasive breast cancer or T4, N1, N2, or M1 stage, or who had axillary radiation were excluded. Two groups were defined for analysis: node-negative with no systemic therapy (n = 1,468) and node-negative with systemic therapy (n = 810). Median follow-up was 7.5 years. Prognostic variables assessed were age at diagnosis, tumor size, tumor grade, invasion of lymphatics, veins, or nerves, estrogen receptor status, and number of nodes removed.

RESULTS

For patients not receiving systemic therapy, regional relapse was significantly increased with smaller numbers of nodes removed (P =.03). There was a trend toward shorter overall survival with fewer nodes removed (P =.06). Node-negative patients who received systemic therapy did not have a higher regional relapse rate or shorter overall survival when fewer nodes were recovered.

CONCLUSION

Recovery of a small number of negative lymph nodes at axillary dissection likely understages patients and leads to undertreatment, resulting in an increased regional relapse rate and poorer survival. The use of systemic therapy may overcome this effect. The number of nodes removed, in conjunction with other prognostic factors, may be useful in selecting node-negative patients for systemic therapy.

Differences detected in vivo between samples of aflatoxin-contaminated peanut meal, following decontamination by two ammonia-based processes

A sample of peanut meal, highly contaminated with aflatoxins, has been subjected to decontamination by two commercial ammonia-based processes. The original contaminated and the two decontaminated meals were fed to rats for 90 days. No lesions associated with aflatoxin-induced hepatocarcinogenesis were detected histologically following feeding with the two detoxified meals. There were, however, clear differences between the two meals in respect of growth rates of the rats. In addition, feeding one of the detoxified meals resulted in hepatic abnormalities detected using novel immunohistochemical reagents. Differences between the two detoxified meals were also indicated by the results of studies using meals 'spiked' with [14C]-aflatoxin B1 prior to being subjected to the detoxification processes. The meals differed in the bioavailability of the label. It was concluded that peanut meal where an initial, unacceptable level of contamination with aflatoxins had been reduced by two ammonia-based processes to comparable, acceptable levels, may still have different effects in vivo when incorporated into animal diets.

N(2)-Aroylanthranilamide inhibitors of human factor Xa

Reversal of the A-ring amide link in 1,2-dibenzamidobenzene 1 (fXa K(ass) = 0.81 x 10(6) L/mol) led to a series of human factor Xa (hfXa) inhibitors based on N(2)-aroylanthranilamide 4. Expansion of the SAR around 4 showed that only small planar substituents could be accommodated in the A-ring for binding to the S1 site of hfXa. Bulky groups such as 4-isopropyl, 4-tert-butyl, and 4-dimethylamino were favored in the B-ring to interact with the S4 site of hfXa. The central (C) ring containing a 5-methanesulfonamido group yielded greater activity than carbamoyl groups. Combining the beneficial features from the B- and C-ring SAR, compound 55 represents the most potent hfXa inhibitor in the N(2)-aroylanthranilamide 4 series with hfXa K(ass) = 58 x 10(6) L/mol (K(i) = 11.5 nM).

Cancer of the tonsil: the results of ipsilateral radiation treatment

BACKGROUND AND PURPOSE

The use of ipsilateral irradiation techniques to treat patients with carcinoma of the tonsil reduces the acute radiation reaction in the contralateral pharynx and late damage to the contralateral salivary tissue. However, this may also spare microscopic disease in apparently uninvolved contralateral lymph nodes. The purpose of this study was to analyse the survival and recurrence rates and sites of recurrance in a group of patients with carcinoma of the tonsil treated with ipsilateral techniques.

MATERIALS AND METHODS

Between 1975 and 1993, 271 patients with invasive squamous cell cancer of the tonsil were referred to the Vancouver Cancer Centre (VCC). One hundred and seventy-eight received ipsilateral radiation treatment. Three received surgery only, six post-operative radiation, 12 supportive treatment only and 72 bilateral radiation treatment. In the absence of bilateral neck nodes and extensive lymphodenopathy, field sizes were generally kept small to include the primary tumour and the first echelon of nodes. The most common dose was 60 Gy in 25 daily fractions in 5 weeks (2.4 Gy per day).

RESULTS AND DISCUSSION

The disease specific survival for all patients treated by radical radiation treatment was 61% at 5 years. For the 178 patients who received ipsilateral radiation treatment the overall primary tumour control rate by ipsilateral radiation treatment alone was 75% and for T1 and T2 tumours 84%. Eight (7.5%) of 101 of these patients with N0 nodes at presentation and without prior failure at the primary site, developed nodal recurrence (four within the initially radiated high dose volume). Two developed contralateral nodes, and two developed field edge nodal recurrence, one cured by surgery. In 54 patients with N1 disease, five developed nodal recurrence, two within field, two contralateral, one of whom was cured by surgery, and one at field edge. In 23 patients with N2a, N2b or N3 disease node control was achieved from radiation treatment in 11 and two more were cured by surgery. All nodal failures were within the radiated volume. Overall, 10 of the 25 patients with nodal failure were cured by subsequent surgery.

CONCLUSIONS

Ipsilateral treatment of patients with carcinoma of the tonsil gives survival results that are at least as good as those reported with bilateral treatment with fewer side effects and a very low risk of failure in the contralateral neck.

Restenosis in human vein bypass grafts

The restenosis rate in vein bypass grafts is higher than in native coronary arteries, and both the cascade of regulatory factors and the vessel reaction may be altered. In this study, vein bypass atherectomy specimens were classified as primary (n = 10) or restenotic (n = 12). Immunohistochemistry with 11 primary antibodies showed low levels of proliferation in both tissues and similar amounts of extracellular matrix components in both primary and restenotic specimens at the time points at which tissue was removed for clinical reasons. Inflammation appeared increased in restenotic specimens. Using in situ hybridization, transforming growth factor-beta1 messenger RNA was detected in both primary and restenotic tissue, with a trend to higher expression in restenosis (8.4 +/- 5.3 vs. 9.4 +/- 7.4 grains/nucleus) and further increased expression in multiple compared with single restenoses (15.1 +/- 6.1 vs. 5.6 +/- 5.1 grains/nucleus, P < 0.05). Hence, there were no great differences in cell proliferation or extracellular matrix formation between primary and restenosis vein graft tissue, in contrast to previously described findings in arterial tissue. This suggests that primary vein graft tissue is already in a chronic 'restenosis-like' state and subsequent injury creates minimal additional upregulation.

Differential expression of nonmuscle myosin II isoforms in human atherosclerotic plaque

Intimal proliferation and functional changes involving vascular smooth muscle cells are key events in the development of atherosclerosis, including restenosis after percutaneous transluminal angioplasty. Nonmuscle myosin (NMM) is required for cytokinesis and has been shown in cultures of vascular smooth muscle cells to undergo changes of isoform expression depending on the stage of proliferation and differentiation. The purpose of this study was to examine the differential expression of the two most recently identified nonmuscle myosin heavy chain isoform II (NMMHC-II) isoforms A and B in atherosclerotic plaque. Primary atherosclerotic and restenotic atherectomy specimens and non-atherosclerotic controls, were analyzed by Western Blot analysis, immunohistochemistry and in situ hybridization. Nonmuscle myosin heavy chain isoform IIA (NMMHC-IIA) was equally expressed in all types of tissue specimens both at the protein and mRNA levels. In contrast, NMMHC-IIB protein was found in restenotic specimens and normal artery but was at very low levels in primary atherosclerotic plaque. By in situ hybridization NMMHC-IIB mRNA levels were significantly greater in restenotic versus primary atherosclerotic lesions. NMMHC-IIB expression is associated with vascular restenosis but is downregulated in stable atherosclerotic lesions, whereas NMMHC-IIA is expressed in both. These results indicate that these new myosin isoforms have different functions and should be regarded separately with respect to smooth muscle proliferation and restenosis. They should prove to be useful molecular markers for the study of atherosclerosis and restenosis.

Therapeutic angiogenesis following arterial gene transfer of vascular endothelial growth factor in a rabbit model of hindlimb ischemia

The plasmid phVEGF165, expressing the 165-amino-acid isoform of vascular endothelial growth factor (VEGF), an endothelial cell specific mitogen, was applied to the polymer coating of an angioplasty balloon and delivered percutaneously to the iliac artery of rabbits in which the femoral artery had been excised to cause hindlimb ischemia. Site-specific transfection of phVEGF165 resulted in augmented development of collateral vessels documented by serial angiograms, and increased capillary density as well as increased capillary/myocyte ratio documented histochemically at necropsy. Consequent amelioration of the hemodynamic deficit in the ischemic limb was documented by improvement in the calf blood pressure ratio (ischemic/normal limb) to 0.70 +/- 0.08 in the VEGF-transfected group vs 0.50 +/- 0.18 in controls (p < 0.05). These findings suggest that site-specific arterial gene transfer of VEGF165 may achieve physiologically meaningful therapeutic modulation of vascular insufficiency.

Apocrine carcinoma of the lip: a case report including immunohistochemical and ultrastructural study, discussion of differential diagnosis, and review of the literature

The light microscopic, immunohistochemical, and ultrastructural features of a case of apocrine carcinoma of the upper lip of a 54-year-old white man are described. The neoplasm had a cribriform intraductal component resembling apocrine carcinoma of the breast. The tumor had irregular borders and infiltrated skeletal muscle. The neoplastic cells had abundant eosinophilic granular cytoplasm and showed apical decapitation secretion characteristic of apocrine differentiation. The differential diagnosis is discussed with particular reference to distinction of the tumor from oncocytic carcinoma and ductal carcinoma of minor salivary gland.

Arterial gene transfer for therapeutic angiogenesis in patients with peripheral artery disease

The age-adjusted prevalence of peripheral arterial disease (PAD) in the U.S. population has been estimated to approach 12%. The clinical consequences of occlusive peripheral arterial disease (PAD) include pain on walking (claudication), pain at rest, and loss of tissue integrity in the distal limbs; the latter may ultimately lead to amputation of a portion of the lower extremity. Surgical bypass techniques and percutaneous catheter-based interventions may be used to successfully revascularize the limbs of certain patients with PAD. In many patients, however, the anatomic extent and distribution of arterial occlusion is too severe to permit relief of pain and/or healing of ischemic ulcers. No effective medical therapy is available for the treatment of such patients. The purpose of this clinical protocol is to document the safety of therapeutic angiogenesis achieved in this case by percutaneous catheter-based delivery of the gene encoding vascular endothelial growth factor (VEGF) in patients with PAD; and, as secondary objectives, investigate the bioactivity of this strategy to relieve rest pain and heal ischemic ulcers of the lower extremities. The rationale for this human protocol is based upon preclinical studies performed in a rabbit model of hindlimb ischemia. These studies are described in detail below and in the manuscripts enclosed in the Appendix to this proposal. In brief, a single intra-arterial bolus of VEGF recombinant human protein, delivered percutaneously to the ischemic limb via an intravascular catheter, resulted in angiographic, hemodynamic, physiologic, and histologic evidence of augmented collateral artery development. Subsequently, similar results were achieved using an angioplasty catheter with a hydrogel-coated balloon to deliver 400 micrograms of a plasmid containing the cDNA for VEGF to the internal iliac artery in the same animal model. Accordingly, we propose to administer arterial gene (VEGF) therapy to patients with rest pain and/or ischemic leg ulcers considered not to be candidates for conventional revascularization techniques. The dose of plasmid to be administered will be progressively escalated beginning with 500 micrograms for the first four patients, 1000 micrograms for the following six patients, 2000 micrograms for the third group of six patients, and 400 micrograms for the fourth group of six patients.

Processing of chimeric antisense oligonucleotides by human vascular smooth muscle cells and human atherosclerotic plaque. Implications for antisense therapy of restenosis after angioplasty

BACKGROUND

Antisense oligonucleotides have been used in animals to inhibit the accumulation of vascular smooth muscle cells (VSMCs) after arterial injury. This has raised prospects for an oligonucleotide-mediated approach to prevent restenosis in patients undergoing angioplasty. However, little is known about the processing of oligonucleotides by human VSMCs or their bioavailability in human atherosclerotic tissue.

METHODS AND RESULTS

Oligonucleotides were synthesized with a mixture of unmodified and sulfur-modified linkages (S-chimeric oligonucleotides). These were more stable than unmodified oligonucleotides and could be recovered from within human VSMCs after 36 hours. Oligonucleotide antisense to human proliferating cell nuclear antigen mRNA specifically reduced DNA synthesis (P < .01) and proliferating cell nuclear antigen protein content (P < .05) in human VSMCs. Confocal microscopy of both live and fixed cells showed modest oligonucleotide uptake that was primarily nuclear. Surprisingly, cationic liposomes did not enhance nuclear uptake but led to extensive, punctated cytoplasmic loading without an enhanced antisense effect. Oligonucleotides incubated with human coronary atherosclerosis fragments associated with cells within 1 hour, despite the presence of abundant extracellular matrix.

CONCLUSIONS

S-chimeric oligonucleotides are stable and can specifically inhibit gene expression in human VSMCs. Nuclear transport is a feature of oligonucleotide processing by human VSMCs, indicating a potential influence at the nuclear level rather than with cytoplasmic mRNA. Cationic liposomes increased oligonucleotide uptake but not intracellular bioavailability, and S-chimeric oligonucleotides can be incorporated into cells within human atherosclerotic plaque, despite the presence of a dense extracellular matrix.

Radiation treatment of cervical lymph node metastases from an unknown primary: an analysis of outcome by treatment volume and other prognostic factors

One hundred and forty-four patients with diagnosis of carcinoma involving cervical lymph nodes from an unknown primary site were seen at the Princess Margaret Hospital, Toronto between 1970 and 1986. This paper addresses the outcome of two treatment approaches using radiation treatment as potentially curative therapy. The treatment approaches compared in a retrospective analysis are radiation to the involved node regions alone (85 cases), and radiation to both the nodes and to potential primary sites in the head and neck (59 cases). The overall 5-year survival rate of the entire group of 144 cases was 41%. There was a trend to increased survival in favour of the group receiving radiation to the nodes and potential primary sites (p = 0.07), however, when differences in extent of nodal involvement were considered and adjusted for using the Cox Proportional Hazard Model, no difference in survival, or cause-specific survival was found between the two treatment groups (p = 0.18 and 0.22, respectively). A total of seven head and neck primary cancers were subsequently discovered, six in the group receiving radiation only to the nodes and one in the group receiving radiation to the nodes and primary sites. The results of this retrospective analysis need to be interpreted with caution but suggest that, for some patients with this diagnosis, radiation to the involved node region alone is adequate. A discussion of the literature is presented with attention to the effect of extent of treatment on outcome.

Expression of gax, a growth arrest homeobox gene, is rapidly down-regulated in the rat carotid artery during the proliferative response to balloon injury

gax is a recently described homeobox gene whose expression in the adult is largely confined to cardiovascular tissues, gax has been shown to be rapidly down-regulated in cultured vascular smooth muscle cells (VSMC) upon stimulation by serum or platelet-derived growth factor. The temporal profile of gax expression in vitro matches that of two families of growth arrest genes: the gas genes and the gadd genes. All of these genes are expressed at their highest levels in quiescent cells and are down-regulated following mitogen activation. Here we report that gax is also down-regulated in vivo in the vascular wall in response to endothelial denudation by balloon angioplasty. The reduction in steady state levels of gax mRNA is transient and occurs with a similar time course to that seen in vitro. The down-regulation of gax in response to balloon injury mirrors the up-regulation seen in a number of early response genes such as c-myc and c-fos. This report is the first to document the in vivo expression of a growth arrest gene which regulates proliferation of vascular smooth muscle cells. In addition, in contrast with previous reports which have demonstrated up-regulation of several genes following balloon injury and/or angioplasty, the present report demonstrates the down-regulation of a regulatory gene within hours of balloon injury. The characteristics of gax suggest it may be required to maintain the gene expression of proteins in VSMC that are associated with the nonproliferative or contractile phenotype in smooth muscle cells.

Use of the rabbit ear artery to serially assess foreign protein secretion after site-specific arterial gene transfer in vivo. Evidence that anatomic identification of successful gene transfer may underestimate the potential magnitude of transgene expression

BACKGROUND

The development of molecular strategies for the treatment of restenosis has been hindered by low efficiencies of in vivo arterial transfection. Expression of intracellular marker proteins is generally evident in < 1% of vascular smooth muscle cells after in vivo arterial transfection. Efforts to improve the efficiency of in vivo gene transfer have been further impeded by the use of transgenes encoding for intracellular marker proteins, necessitating tissue removal and limiting survey for expression to one point in time.

METHODS AND RESULTS

To study gene expression on a serial basis in vivo and determine the relation between a secreted gene product and transfection efficiency after in vivo arterial gene transfer, a method for performing and serially monitoring gene expression in vivo was developed using the central artery of the rabbit ear. Liposome-mediated transfection of plasmid DNA containing the gene for human growth hormone (hGH) was successfully performed in 18 of 23 arteries. Serum hGH levels measured 5 days after transfection ranged from 0.1 to 3.8 ng/mL (mean, 0.97 ng/mL); in contrast, serum drawn from the control arteries demonstrated no evidence of hGH production. Serial measurement of hGH from transfected arteries demonstrated maximum hGH secretion 5 days after transfection and no detectable hormone after 20 days. Despite these levels of secreted gene product documented in vivo, immunohistochemical staining of sections taken from the rabbit ear artery at necropsy disclosed only rare cells in which there was evidence of successful transfection.

CONCLUSIONS

These experiments demonstrate a useful method of performing serial in vivo analyses of gene expression after vascular transfection and that anatomic analyses of transfection efficiency may underestimate the potential magnitude of expression in the case of a secreted gene product. These findings have implications for the clinical application of somatic gene therapy because low-efficiency transfection with a gene encoding for a secreted protein may achieve therapeutic effects not realized by transfection with genes encoding for proteins that remain intracellular.

Increased gene expression after liposome-mediated arterial gene transfer associated with intimal smooth muscle cell proliferation. In vitro and in vivo findings in a rabbit model of vascular injury

Arterial gene transfer represents a novel strategy that is potentially applicable to a variety of cardiovascular disorders. Attempts to perform arterial gene transfer using nonviral vectors have been compromised by a low transfection efficiency. We investigated the hypothesis that cellular proliferation induced by arterial injury could augment gene expression after liposome-mediated gene transfer. Nondenuded and denuded rabbit arterial strips were maintained in culture for up to 21 d, after which transfection was performed with a mixture of the plasmid encoding firefly luciferase and cationic liposomes. In non-denuded arteries, the culture interval before transfection did not affect the gene expression. In contrast, denuded arteries cultured for 3-14 d before transfection yielded 7-13-fold higher expression (vs. day 0; P < 0.005). Transfection was then performed percutaneously to the iliac arteries of live rabbits with or without antecedent angioplasty. Gene expression increased when transfection was performed 3-7 d postangioplasty (P < 0.05). Proliferative activity of neointimal cells assessed in vitro by [3H]thymidine incorporation, and in vivo by immunostaining for proliferating cell nuclear antigen, increased and declined in parallel with gene expression. These findings thus indicate that the expression of liposome-mediated arterial gene transfer may be augmented in presence of ongoing cellular proliferation.

Liposome-mediated gene transfer into human vascular smooth muscle cells

BACKGROUND

Complexing recombinant DNA with cationic liposomes is a convenient means of introducing foreign genes into cells (lipofection) and could potentially form the basis for genetically modifying diseased blood vessels in patients. The mechanism of lipofection is incompletely understood, but it is recognized that the degree of successful gene transfer is highly dependent on cell type. To date, there has been no reported experience with lipofection of human vascular smooth muscle cells.

METHODS AND RESULTS

Primary cultures of human vascular smooth muscle cells were transfected under optimized conditions with a plasmid expressing either firefly luciferase (Luc) or nuclear-localized beta-galactosidase (NL-beta-gal). Cells were derived from either normal human internal mammary arteries (n = 6), fragments of primary atherosclerotic plaque (n = 4), or fragments of restenotic lesions (n = 5). Concurrent lipofection of rabbit vascular smooth muscle cells and NIH 3T3 cells was performed as well. Cultures derived from 15 patients all demonstrated positive expression of the reporter gene. Compared with NIH 3T3 cells, however, expression in human vascular smooth muscle cells was markedly reduced: in cells derived from internal mammary artery, Luc expression, normalized for protein content, was 123-fold lower than in NIH 3T3 cells, whereas the proportion of cells expressing NL-beta-gal was 30-fold lower. Luc expression in cells derived from restenotic tissue was significantly greater than from cells derived from primary plaque (P < .03). Within a given population of cells, the mitotic index of cells expressing the recombinant gene was significantly higher than the mitotic index for the total population of cells (P < .05). Finally, cotransfection experiments, in which lipofection of smooth muscle cells was performed using genes for NL-beta-gal and for human growth hormone, showed that among positive transfects, a high proportion of cells (23% to 36%) coexpressed both genes.

CONCLUSIONS

The efficiency of successful lipofection in human vascular smooth muscle cells in vitro is low. Transfection appears to be preferentially facilitated in cells derived from restenotic tissue, and specific properties of smooth muscle cells, including growth rates, appear to be critical for successful transfection. Further elucidation of cell properties that promote transfection is required to augment the efficiency of liposome-mediated gene transfer in human vascular cells.