Therapeutic efficacy of tumor-targeted IL2 in LTalpha(-/-) mice depends on conditioned T cells

Immunological tumor destruction in a murine melanoma model by targeted LTalpha independent of secondary lymphoid tissue

BACKGROUND

We previously demonstrated that targeting lymphotoxin alpha (LTalpha) to the tumor evokes its immunological destruction in a syngeneic B16 melanoma model. Since treatment was associated with the induction of peritumoral tertiary lymphoid tissue, we speculated that the induced immune response was initiated at the tumor site.

METHODS AND RESULTS

In order to directly test this notion, we analyzed the efficacy of tumor targeted LTalpha in LTalpha knock-out (LTalpha(-/-)) mice which lack peripheral lymph nodes. To this end, we demonstrate that tumor-targeted LTalpha mediates the induction of specific T-cell responses even in the absence of secondary lymphoid organs. In addition, this effect is accompanied by the initiation of tertiary lymphoid tissue at the tumor site in which B and T lymphocytes are compartmentalized in defined areas and which harbor expanded numbers of tumor specific T cells as demonstrated by in situ TRP-2/K(b) tetramer staining. Mechanistically, targeted LTalpha therapy seems to induce changes at the tumor site which allows a coordinated interaction of immune competent cells triggering the induction of tertiary lymphoid tissue.

CONCLUSION

Thus, our data demonstrate that targeted LTalpha promotes an accelerated immune response by enabling the priming of T cells at the tumor site.

Antibody targeted drugs as cancer therapeutics

Treatment of cancer is a double-edged sword: it should be as aggressive as possible to completely destroy the tumour, but it is precisely this aggressiveness which often causes severe side effects - a reason why some promising therapeutics can not be applied systemically. In addition, therapeutics such as cytokines that physiologically function in a para- or autocrine fashion require a locally enhanced level to exert their effect appropriately. An elegant way to accumulate therapeutic agents at the tumour site is their conjugation/fusion to tumour-specific antibodies. Here, we discuss recent preclinical and clinical data for antibody-drug conjugates and fusion proteins with a special focus on drug components that exert their antitumour effects through normal biological processes.