Cancer Therapy : Preclinical Growth Inhibition of Human Multiple Myeloma Cells by an Oncolytic Adenovirus Carrying the CD 40 Ligand Transgene

Purpose: The growth-inhibitory activity of recombinant CD40 ligand (CD40L) is well documented in human multiple myeloma (MM). We examined MM-targeted delivery of CD40L by a conditional replicative oncolytic adenovirus, AdEHCD40L. Experimental Design: The growth-regulatory activity of AdEHCD40L was determined in vitro and in vivo. Differential analysis with AdEHCD40L and parental virus (AdEHNull)–infected cultures allowed the identification of cellular and molecular pathways modulated by the CD40L transgene. Results: Conditional expression of viral E1A and CD40L transgene was shown in human MM lines RPMI 8226 [interleukin (IL)-6 independent] and Kas-6/1 (IL-6 dependent) under hypoxic conditions commonly found in MM in situ. AdEHCD40L inhibited MM cell growth more effectively than AdEHNull. This enhanced growth-inhibitory activity was abrogated by cotreatment with a CD40L antibody. Chemoresistant MM lines (MR20 and LR5) were similarly susceptible to AdEHCD40L treatment. AdEHCD40L induced apoptosis and S-phase cell cycle blockade while uniquely up-regulating the previously described proapoptotic elements tumor necrosis factor–related apoptosis-inducing ligand, Fas, and IL-8. Intratumoral injections of AdEHCD40L reduced the growth of severe combined immunodeficient/hu RPMI 8226 xenografts by >50% compared with 28% reduction by AdEHNull. Adenoviral hexon and CD40L were detected in AdEHCD40L-treated tumors at day 35 after infection primarily in necrotic areas, suggesting viral replicative activity. Conclusions: These findings show that CD40L acts in concert with viral oncolysis to produce MM growth inhibition through activation of cellular apoptosis. The direct growth-inhibitory activity of AdEHCD40L, together with the well-known immunepotentiating features of CD40L, may be clinically applicable for the experimental treatment of MM or plasma cell leukemia. Multiple myeloma (MM) is a B-cell malignancy characterized by the clonal expansion and accumulation of malignant plasma cells in the bone marrow (1). Despite recent advances in induction therapy, the long-term outlook for patients with this disease is poor. Promising new agents, such as thalidomide-like immunomodulatory drugs (lenalidomide) and proteasome inhibitors (bortezomib), have improved prognosis and survival (2), but MM is still incurable. CD40 belongs to the tumor necrosis factor (TNF) receptor superfamily member and is commonly expressed on human B cells. The CD40 pathway is best known for its costimulatory role in B-cell and T-cell proliferation and differentiation. Interestingly, CD40 is commonly expressed on human MM cells (3) but not normal, terminally differentiated plasma cells (4). This differential pattern of expression presents an opportunity for exploiting the CD40 growth-regulatory pathway for growth inhibition of MM. We and others have found that binding of the CD40 receptor by its natural ligand (CD40L, CD154) produced Authors' Affiliations: Cancer Immunology Research Laboratory and Department of Pathology, Baylor Sammons Cancer Center, Baylor University Medical Center; Gradalis, Inc., Dallas, Texas; Institute of Biomedical Studies, Baylor University, Waco, Texas; and Center for Applied Medical Research, University of Navarra, Pamplona, Spain Received 2/21/09; revised 4/30/09; accepted 5/5/09; published OnlineFirst 7/21/09. Grant support: LeukemiaTexas, Edward and Ruth Wilkof Foundation, Robert A. Schanbaum Memorial Fund, and Sammons Cancer Center Research Fund. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Current address for M.S. Fernandes: Department of Medical Oncology, DanaFarber Cancer Institute, 44 Binney Street, Mayer 540, Boston, MA 02115. Requests for reprints: Marvin J. Stone, Baylor Sammons Cancer Center, 3500 Gaston Avenue, Dallas, TX 75246. E-mail: marvins@baylorhealth.edu. F 2009 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-09-0451 4847 Clin Cancer Res 2009;15(15) August 1, 2009 www.aacrjournals. org Research. on January 6, 2018. © 2009 American Association for Cancer clincancerres.aacrjournals. org Downloaded from Published OnlineFirst July 21, 2009; DOI: 10.1158/1078-0432.CCR-09-0451