Vaccin tegen prostaatkanker blijkt effectief tonen dierstudies aan.

21 juni 2011: Bron: Nature

Dierstudies tonen aan dat een vaccin tegen prostaatkanker effectief kan zijn. Dit blijkt uit een artikel in Nature. Hier het abstract van deze studie met vooraf enkele citaten uit een artikel in Medscape over dezelfde studie. Opmerkelijk dat de onderzoekers zeggen dat deze manier van immuuntherapie bij heel patienten zou kunen worden toegepast.

Bron: Medscape: lees hier het volledige artikel

Animal studies of a new human prostate cancer vaccine show that repeated intravenous injections can destroy well-established prostate tumors in mice, without adjuvant chemotherapy or radiation and with no apparent adverse effects.........

The vaccine was developed by inserting a cDNA library from healthy human prostate tissue into mutated vesicular stomatitis viruses, which were then cultured and given to test mice with established prostate tumors. The results showed that 9 intravenous injections cured more than 80% of the established tumors in the mice, without triggering autoimmunity.

"Nobody knows how many antigens the immune system can really see on tumor cells," senior author Richard Vile, PhD, said in a press statement. "By expressing all of these proteins in highly immunogenic viruses, we increased their visibility to the immune system. The immune system now thinks it is being invaded by the viruses, which are expressing cancer-related antigens that should be eliminated."..........

New Approach Targets Tumor From Many Routes

Previous attempts to vaccinate against prostate and other types of cancerous tumors have been hampered, largely by the inability of researchers to isolate a sufficiently diverse and robust collection of antigens in tumor cells. Because of this, tumors often mutate and reestablish themselves in spite of the body's immune system. The use of viruses as vectors for cDNA libraries overcomes the difficulty of isolating antigens in tumor cells by giving the immune system a more complete picture of the cancerous invader.

This approach used doses of a vaccine that contained a library of DNA with multiple fragments of genes and, therefore, many possible antigens. This approach did not send the immune system into overdrive, which had been a concern. Instead, the range of DNA meant that the vaccine was able to target the tumor through many routes.

Importantly, the DNA library was harvested from the same organ as the tumor. This meant that the immune system self-selected the cancer antigens it respond to, and did not react against healthy parts of the body. The fact that the process of self-selection was triggered when the vaccine was injected intravenously means that the vaccine can be given systemically, obviating the need for tumor targeting.

The authors write that "with this approach, a broad repertoire of individually weak T-cell responses is raised against multiple [tumor-associated antigens], imposing a cumulatively strong selective pressure against immune escape, and no tumors have to be accessed by targeted vector delivery." Read more>>>>>>

Broad antigenic coverage induced by vaccination with virus-based cDNA libraries cures established tumors

Bron: Nature

Broad antigenic coverage induced by vaccination with virus-based cDNA libraries cures established tumors

Effective cancer immunotherapy requires the release of a broad spectrum of tumor antigens in the context of potent immune activation. We show here that a cDNA library of normal tissue, expressed from a highly immunogenic viral platform, cures established tumors of the same histological type from which the cDNA library was derived. Immune escape occurred with suboptimal vaccination, but tumor cells that escaped the immune pressure were readily treated by second-line virus-based immunotherapy. This approach has several major advantages. Use of the cDNA library leads to presentation of a broad repertoire of (undefined) tumor-associated antigens, which reduces emergence of treatment-resistant variants and also permits rational, combined-modality approaches in the clinic. Finally, the viral vectors can be delivered systemically, without the need for tumor targeting, and are amenable to clinical-grade production. Therefore, virus-expressed cDNA libraries represent a novel paradigm for cancer treatment addressing many of the key issues that have undermined the efficacy of immuno- and virotherapy to date.

antigens, cdna, established, library, vaccine, broad, approach, libraries, viruses, cures