Interleukin-2 gene therapy of residual EL-4 leukaemia potentiates the effect of cyclophosphamide pretreatment

Surgical organ perfusion method for gene transfer into cells of the perifollicular area of the spleen: an experimental trial on farm pigs

In an attempt to develop a gene therapy method for splenic and systemic diseases, an evaluation was made of surgical methods for gene transfer into porcine spleen. We have developed a continuous closed-circuit organ perfusion method for gene transfer into porcine spleen. For gene transfer, we used a type-5 replication defective adenovirus vector expressing the E. coli beta-galactosidase gene as a reporter gene. In eight young 22-35 kg farm pigs, the spleen was perfused in vivo with the viral solution via laparotomy, for 30 or 60 min. Gene transfer was determined visually on histological cryosections after X-gal and PAS staining. Infusion of the viral solution through the splenic artery did not result in gene expression. Perfusion of spleen in vivo resulted in beta-galactosidase reporter gene expression in the macrophages located around capillaries terminating in the perifollicular zone and in the red pulp examined after four days. The present results suggest that the surgically performed spleen perfusion method can be used for gene transfer in the treatment of diseases having splenic manifestations and in systemic diseases.

Interleukin-2 gene therapy of surgical minimal residual tumour disease

Our study was designed to examine the effects of IL-2 gene therapy in a surgical minimal residual tumour disease (SMRTD). Mice were inoculated s.c. with methylcholanthrene (MC)-induced MC12 sarcoma cells. When the tumours reached 8 to 12 mm in diameter, they were excised, either completely ("microscopic SMRTD") or incompletely ("macroscopic SMRTD"). On day 90 after surgery, the tumour recurrence rate in untreated mice with microscopic SMRTD was approximately 30%, whereas in those with macroscopic SMRTD it was 75%. After surgery, experimental mice were treated with 2 types of irradiated, IL-2 gene-modified, IL-2-producing tumour cell vaccine. One type of vaccine was derived from the MC12 sarcoma cells (MC12-1L2/IV-3); the other type was derived from an unrelated X63-Ag8.653 plasmacytoma (X63-m-IL-2). Both types of vaccine failed to cure the macroscopic SMRTD. Whereas the X63-m-IL-2 vaccine was also ineffective in the microscopic SMRTD, the MC12-IL2/IV-3 vaccine was capable of preventing growth in all but one mouse (1164) with microscopic SMRTD when administered 2 to 5 days after surgery. If the vaccination took place 2 days before surgery or later than 5 days after surgery, the therapeutic activity was lost. Vaccination with irradiated parental MC12 cells did not produce any significant benefit compared to the operated-only mice. The protective effect of the MC12-L2/IV-3 vaccine was specific and comparatively long-lasting. Vaccinated mice, which had rejected the MC12 tumour residuum, were capable of rejecting a second inoculum of the MC12 sarcoma cells injected on days 35 to 110 after surgery but succumbed to the growth of 2 other unrelated murine sarcomas carrying different tumour-rejection antigens.

Cytokines in animal models of cancer

Cytokines are a complex family of mediators that play a wide role in development, immunity, inflammation and tissue repair. Their use in therapy is still in its infancy and animal models have a key role to play in optimizing doses and schedules. Whilst xenogeneic and syngeneic transplantable systems have traditionally been used to look at the effects of cytokines in tumour models, oncogene transgenic mice prone to develop cancer, may now have a role to play. Moreover, gene therapy has allowed the investigation of ectopically expressed high and continuous levels of cytokines. We will attempt to review the literature on the effect of cytokines and their combinations in these models of cancer.

Cytokine gene-modified vaccines in the therapy of cancer

Therapeutic strategies based on the insertion of cytokine genes into the genome of tumour cells, followed by vaccination with the resulting genetically modified, cytokine-producing cells, represent a new potential prospect for treatment of cancer patients. In this review, the concept of cytokine gene-modified cancer vaccines is discussed; the discussion is focused on the rationale, characterization, progress in the development, preclinical testing, and first clinical trials. An effort is made to analyse and integrate the results obtained in different experimental model systems in order to determine the needed approaches and directions for further research.