Targeted delivery of interferon-alpha via fusion to anti-CD20 results in potent antitumor activity against B-cell lymphoma

Abstract

The anti-CD20 antibody rituximab has substantially improved outcomes in patients with B-cell non-Hodgkin lymphomas. However, many patients are not cured by rituximab-based therapies, and overcoming de novo or acquired rituximab resistance remains an important challenge to successful treatment of Bcell malignancies. Interferon-alpha (IFN␣) has potent immunostimulatory properties and antiproliferative effects against some B-cell cancers, but its clinical utility is limited by systemic toxicity. To improve the efficacy of CD20-targeted therapy, we constructed fusion proteins consisting of anti-CD20 and murine or human IFN␣. Fusion proteins had reduced IFN␣ activity in vitro compared with native IFN␣, but CD20 targeting permitted efficient antiproliferative and proapoptotic effects against an aggressive rituximab-insensitive human CD20 ؉ murine lymphoma (38C13-huCD20) and a human B-cell lymphoma (Daudi). In vivo efficacy was demonstrated against established 38C13-huCD20 grown in syngeneic immunocom- IntroductionThe anti-CD20 antibody rituximab (C2B8/Rituxan; Genentech/ Biogen-IDEC) has substantially improved treatment outcomes in B-cell non-Hodgkin lymphomas (NHLs), achieving high response rates in low-grade B-cell lymphomas, 1 and improving survival in both indolent and aggressive lymphomas in combination with chemotherapy. 2,3 However, many tumors do not respond to or relapse after rituximab-based therapies. 4 Thus, new approaches are needed to improve anti-CD20 efficacy and overcome rituximab resistance.The in vivo antilymphoma effects of rituximab are believed to be mediated by antibody dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), induction of apoptosis in tumor cells, and recruitment of T cells responding to tumor antigens released upon antibody-mediated tumor lysis. [5][6][7] Clinical studies have suggested that ADCC plays a dominant role in rituximab action in humans. 8,9 Thus, attempts have been made to boost rituximab-mediated ADCC by activation of Fc receptorbearing natural killer (NK) cells, monocytes/macrophages, or granulocytes via systemic administration of cytokines such as interleukin-2, interleukin-12, or granulocyte-macrophage colonystimulating factor, 10-12 with limited efficacy. None of these trials involving systemic administration of cytokines offered a clear advantage over the expected efficacy of rituximab alone, likely due to the inability of systemically administered agents to achieve high concentrations within the tumor bed.Interferon-alpha (IFN␣), a member of the type I interferon family (␣, ␤, ), is a pleiotropic cytokine with attractive features for combination with rituximab in treating NHL. 13,14 Beneficial properties of IFN␣ against NHL and other cancers include direct antiproliferative and proapoptotic effects, 15-17 blockade of autocrine growth factor loops, 18 repression of c-myc oncogene expression, 19 down-regulation of telomerase activity, 20 and inhibition of angiogenesis. 21 Favorable immunologic effects of IFN␣ for lymphoma treatment...

Anti-CD20-interleukin-21 fusokine targets malignant B cells via direct apoptosis and NK-cell–dependent cytotoxicity

“…21,34 Apart from its immunostimulatory effects, IL-21 exerts direct cytotoxicity on a variety of IL-21R-expressing NHLs, including diffuse large B-cell lymphoma (DLBCL), MCL, chronic lymphocytic leukemia, and follicular lymphoma. 32,[35][36][37][38][39][40][41][42] We found that the direct apoptotic effects of IL-21 in DLBCL and MCL were mediated via activation of an IL-21R-dependent signaling pathway that leads to phosphorylation of STATs followed by upregulation of cMyc and Bax and downregulation of BCL-2 and BCL-XL. 32,35 These studies suggest IL-21 may become a potent adjuvant to cancer immunotherapy against B-cell lymphoma.…”

“…Use of immunocompetent mice allows recruitment of the full range of host innate and adaptive immune effector mechanisms activated by the fusokine that should contribute to lymphoma eradication. 32,39 Further, this model also allows testing of the fusokine in cells resistant to rituximab therapy. In vivo treatment of mice bearing A20-hCD20 tumors with the aCD20-IL-21 fusokine resulted in significant delay in tumor growth and prolonged animal survival compared with treatment with aCD20-IgG1 alone or together with IL-21.…”

“…In preclinical studies, fusion of type I interferons (IFNa/b) with CD20 mAb demonstrated potent antilymphoma effects in B-cell lymphoma tumor models. 39,40 Fusion of granulocyte-macrophage colony-stimulating factor and IL-21 (GIFT-21) activated immune response and led to antitumor responses in the B16 xenograft model. 41 A recent study of IL-2 fusion with fragment constant (Fc) region (Fc/IL-2) resulted in significant tumor control in isogenic tumor models.…”

Targeting and utilizing primary tumors as live vaccines: changing strategies

“…For instance, it has been shown that the therapeutic effect is greatly improved when antibodies are conjugated to immune modulators. 26,27 Local ablative radiation therapy (RT) The antitumor effect of RT depends on the dose and treatment schedule. Our review focused on the use of ablative RT, during which a high dose of radiation is precisely delivered to small tumors.…”

Targeted immunotherapy using anti-CD138-interferon α fusion proteins and bortezomib results in synergistic protection against multiple myeloma

“…This approach has been used effectively to target IFN to various tumors. [8][9][10][11] To target IFN to MM, we fused it to the B-B4 antibody that specifically binds CD138. 8,12 CD138, also known as syndecan-1, is highly expressed on mature plasma cells, making it a suitable target for MM.…”