A recombinant canarypox virus (ALVAC) expressing feline interleukin-2 (IL-2) (an important T cell stimulatory cytokine approved as an exogenous anti-tumour agent) is approved for use as adjunctive immunotherapy after surgery and brachytherapy for primary FISS in cats without enlarged lymph nodes and lung metastasis. This evidence concerns the gene IL2 and neoplasm.