• Sophie Escutenaire, Vincenzo Cerullo, Iulia Diaconu, Laura Ahtiainen, Päivi Hannuksela, Minna Oksanen, Elina Haavisto, Aila Karioja-Kallio, Sirkka-Liisa Holm, Lotta Kangasniemi, Camilla Ribacka, Satu Kauppinen, Timo Joensuu, T Petteri Arstila, Sari Pesonen, Anna Kanerva, and Akseli Hemminki.
• Cancer Gene Therapy Group, Transplantation Laboratory, Haartman Institute and Finnish Institute of Molecular Medicine, University of Helsinki, Finland.
• Ann. Med. 2011 Mar 1; 43 (2): 151-63.

BackgroundSuccessful tumor targeting of systemically administered oncolytic adenoviruses may be hindered by interactions with blood components.Materials And MethodsBlood distribution of oncolytic adenoviruses featuring type 5 adenovirus fiber, 5/3 capsid chimerism, or RGD-4C in the fiber knob was investigated in vitro and in patients with refractory solid tumors.ResultsVirus titers and prevalence in serum of patients increased over the first post-treatment week, suggesting replication. Detection of low virus loads was more sensitive in blood clots than in serum, although viral levels > 500 viral particles/mL did not differ significantly between both sample types. While adenovirus bound to erythrocytes, platelets, granulocytes, and peripheral blood mononuclear cells in vitro, the virus was mainly detectable in erythrocytes and granulocytes in cancer patients. Taken together with a temporary post-treatment decrease in thrombocyte counts, platelet activation by adenovirus and subsequent clearance seem likely to occur in humans. Fiber modifications had limited observed effect on virus distribution in blood cell compartments. Neutrophils, monocytes and cytotoxic T lymphocytes were the major leukocyte subpopulations interacting with adenoviruses.ConclusionSerum and blood clots are relevant to estimate oncolytic adenovirus replication. Insight into viral interactions with blood cells may contribute to the development of new strategies for tumor delivery.

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