Definition

An antibody-dye conjugate composed of basiliximab, a chimeric monoclonal antibody directed against the alpha subunit of interleukin-2 receptor (IL-2R alpha, CD25 or Tac antigen), and conjugated to the light-activatable phthalocyanine dye IR700 (IRDye 700DX), with potential antineoplastic activity. Upon intravenous administration of basiliximab-IR700 RM-1995, the basiliximab moiety targets and binds to IL-2R alpha expressed on the surface of activated regulatory T lymphocytes (Tregs) in the tumor microenvironment (TME). Upon binding and localized application of 690nm nonthermal red light using the PIT690 laser system, the IR700 dye transiently becomes activated, disrupts the cell membrane and selectively kills the IL-2R alpha-expressing Tregs. This may abrogate the Tregs-mediated immunosuppressive nature of the TME and may result in systemic anti-cancer immune activation. This may activate a cytotoxic T-lymphocyte (CTL)-mediated immune response against tumor cells. CD25-positive Tregs inhibit antitumor immune responses and enhance tumor growth.