Reiko E. Yamada

Phase I Study of Ipilimumab, an Anti–CTLA-4 Monoclonal Antibody, in Patients with Relapsed and Refractory B-Cell Non–Hodgkin Lymphoma

Purpose: The growth of non–Hodgkin lymphomas can be influenced by tumor–immune system interactions. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative regulator of T-cell activation that serves to dampen antitumor immune responses. Blocking anti–CTLA-4 monoclonal antibodies improves host resistance to immunogenic tumors, and the anti–CTLA-4 antibody ipilimumab (MDX-010) has clinical activity against melanoma, prostate, and ovarian cancers. Experimental Design: We did a phase I trial of ipilimumab in patients with relapsed/refractory B-cell lymphoma to evaluate safety, immunologic activity, and potential clinical efficacy. Treatment consisted of ipilimumab at 3 mg/kg and then monthly at 1 mg/kg × 3 months (dose level 1), with subsequent escalation to 3 mg/kg monthly × 4 months (dose level 2). Results: Eighteen patients were treated, 12 at the lower dose level and 6 at the higher dose level. Ipilimumab was generally well tolerated, with common adverse events attributed to it, including diarrhea, headache, abdominal pain, anorexia, fatigue, neutropenia, and thrombocytopenia. Two patients had clinical responses; one patient with diffuse large B-cell lymphoma had an ongoing complete response (>31 months), and one with follicular lymphoma had a partial response lasting 19 months. In 5 of 16 cases tested (31%), T-cell proliferation to recall antigens was significantly increased (>2-fold) after ipilimumab therapy. Conclusions: Blockade of CTLA-4 signaling with the use of ipilimumab is well tolerated at the doses used and has antitumor activity in patients with B-cell lymphoma. Further evaluation of ipilimumab alone or in combination with other agents in B-cell lymphoma patients is therefore warranted. (Clin Cancer Res 2009;15(20):6446–53)

Programmed death ligand 1 is expressed by non-hodgkin lymphomas and inhibits the activity of tumor-associated T cells.

Purpose: Programmed death ligand 1 (PD-L1) is expressed on antigen-presenting cells and inhibits activation of T cells through its receptor PD-1. PD-L1 is aberrantly expressed on some epithelial malignancies and Hodgkin lymphomas and may prevent effective host antitumor immunity. The role of PD-L1 in non–Hodgkin lymphomas (NHL) is not well characterized. Experimental Design: PD-L1 expression was analyzed in cell lines and lymphoma specimens by using flow cytometry and immunohistochemistry. Functional activity of PD-L1 was studied by incubating irradiated lymphoma cells with allogeneic T cells with or without anti-PD-L1 blocking antibody; T-cell proliferation and IFN-γ secretion served as measures of T-cell activation. Similar experiments were conducted using cultures of primary lymphoma specimens containing host T cells. Results: PD-L1 was expressed uniformly by anaplastic large cell lymphoma (ALCL) cell lines, but rarely in B-cell NHL, confined to a subset of diffuse large B-cell lymphomas (DLBCL) with activated B-cell features (3 of 28 cell lines and 24% of primary DLBCL). Anti-PD-L1 blocking antibody boosted proliferation and IFN-γ secretion by allogeneic T cells responding to ALCL and DLBCL cells. In autologous cultures of primary ALCL and DLBCL, PD-L1 blockade enhanced secretion of inflammatory cytokines IFN-γ, granulocyte macrophage colony-stimulating factor, interleukin (IL)-1, IL-6, IL-8, IL-13, TNF-α, and macrophage inflammatory protein-1α. In establishing cell lines from an aggressive PD-L1+ mature B-cell lymphoma, we also noted that PD-L1 expression could be lost under certain in vitro culture conditions. Conclusions: PD-L1 may thwart effective antitumor immune responses and represents an attractive target for lymphoma immunotherapy. Clin Cancer Res; 17(13); 4232–44. ©2011 AACR.

A Phase I Dose-Finding Trial of Recombinant Interleukin-21 and Rituximab in Relapsed and Refractory Low Grade B-cell Lymphoproliferative Disorders

Purpose: We conducted a phase I study to determine the safety, maximum-tolerated dose (MTD), and efficacy of weekly bolus recombinant human interleukin-21 (rIL-21) plus rituximab in patients with indolent B-cell malignancies. Experimental Design: One week after a lead-in rituximab dose, cohorts of three patients were treated with 30, 100, or 150 μg/kg rIL-21 weekly for four weeks, concurrent with four weekly doses of rituximab. Patients with stable disease or better were eligible for a second course of therapy. Results: Twenty-one patients with relapsed small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL, n = 11), follicular lymphoma (n = 9), or marginal zone lymphoma (n = 1) were enrolled, with 19 completing at least one course of therapy. The MTD for rIL-21 was 100 μg/kg, based on observed toxicities including nausea, vomiting, diarrhea, hypotension, edema, and hypophosphatemia. Clinical responses were seen in 8 of 19 evaluable patients (42%; 3 CR/CRu, 5 PR), with 4 of longer duration than the patients previous response to rituximab-based treatment (median 9 months vs. 3 months). Conclusions: Outpatient therapy of indolent B-cell malignancies with rituximab and weekly rIL-21 was well tolerated and clinically active, with durable complete remissions in a small subset of patients. Additional studies of rIL-21 and anti-CD20 antibodies in lymphoma and SLL/CLL are warranted. Clin Cancer Res; 18(20); 5752–60. ©2012 AACR.

In vivo gene transfer of pigment epithelium-derived factor inhibits tumor growth in syngeneic murine models of thoracic malignancies

OBJECTIVE Pigment epithelium-derived factor is known to be an inhibitor of angiogenesis. We hypothesized that in vivo gene transfer of pigment epithelium-derived factor may inhibit tumor angiogenesis and growth in syngeneic models of thoracic malignancies. METHODS An adenovirus vector encoding the human pigment epithelium-derived factor cDNA (AdPEDF) was used to transduce human lung cancer cells in vitro. Transgene expression was assessed using Western analysis. Three different murine flank tumors (2 lung, 1 colon) were then established in syngeneic mice and treated intratumorally with phosphate-buffered saline, AdPEDF, or an empty vector (AdNull). Endpoints measured included transgene expression, tumor size, and animal survival, as well as microvessel density within the tumor. Additionally, a murine pulmonary metastasis model was established by intravenous injection of a syngeneic colon adenocarcinoma cell line expressing a marker gene (beta-galactosidase). One day later, treatment (phosphate-buffered saline, AdNull, or AdPEDF) was administered intrapleurally. Tumor burden (gross and histologic inspection, lung weight, and beta-galactosidase expression) was then evaluated 13 days after vector dosing, and survival was recorded. RESULTS AdPEDF-derived expression of pigment epithelium-derived factor was demonstrated in vitro and in vivo. In syngeneic murine lung cancer flank tumors, intratumoral administration of AdPEDF significantly inhibited tumor growth (P <.01), prolonged mouse survival (P <.01), and decreased microvessel density (P <.01) compared with control groups. In the pulmonary metastasis model, AdPEDF-treated mice exhibited significantly reduced lung lesions, lung weight (P <.0005), beta-galactosidase expression (P <.05), and animal survival was prolonged (P <.05). CONCLUSION Gene transfer of pigment epithelium-derived factor suppresses tumor vascularization and growth, while prolonging survival in syngeneic murine models of thoracic malignancies.

Intratumoral but not systemic delivery of CpG oligodeoxynucleotide augments the efficacy of anti-CD20 monoclonal antibody therapy against B cell lymphoma.

The anti-CD20 monoclonal antibody rituximab (Rituxan) has become a mainstay in the treatment of B cell non-Hodgkin lymphomas. The mechanisms of action for rituximab include antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity, and apoptosis induction. Combination of anti-CD20 antibodies with immunostimulatory agents may improve their efficacy via enhancement of one or more of these mechanisms. Toll-like receptor 9 agonist CpG oligodeoxynucleotides administered systemically have been studied in clinical trials with and without rituximab. However, recent data suggest that intratumoral (IT) delivery of CpG has advantages in the treatment of tumors. Using a syngeneic murine B cell lymphoma line expressing human CD20, we found that IT, but not systemically administered CpG significantly improved the efficacy of rituximab against 7-day established tumors. Rituximab plus IT CpG could eradicate tumors from 42% of mice, whereas systemically administered CpG, with or without rituximab, did not achieve tumor eradication. Both natural killer cells and complement participated in the cure of tumors by rituximab plus IT CpG, apparently by increasing tumor cell sensitivity to complement and ADCC lysis, and by augmenting the cytotoxicity of ADCC effectors. No role for T cells in mediating tumor eradication was demonstrated in this model. These results suggest that previous clinical trials in B cell lymphoma combining systemic administration of CpG with rituximab may have employed suboptimal routes of CpG delivery. Future trials combining IT CpG with anti-CD20 antibodies or the antibody-mediated targeting of CpG directly to the sites of B cell lymphoma may thus be warranted.

Maleimide conjugation markedly enhances the immunogenicity of both human and murine idiotype-KLH vaccines

The collection of epitopes present within the variable regions of the tumor-specific clonal immunoglobulin expressed by B cell lymphomas (idiotype, Id) can serve as a target for active immunotherapy. Traditionally, tumor-derived Id protein is chemically conjugated to the immunogenic foreign carrier protein keyhole limpet hemocyanin (KLH) using glutaraldehyde to serve as a therapeutic vaccine. While this approach offered promising results for some patients treated in early clinical trials, glutaraldehyde Id-KLH vaccines have failed to induce immune and clinical responses in many vaccinated subjects. We recently described an alternative conjugation method employing maleimide-sulfhydryl chemistry that significantly increased the therapeutic efficacy of Id-KLH vaccines in three different murine B cell lymphoma models, with protection mediated by either CD8(+) T cells or antibodies. We now define in detail the methods and parameters critical for enhancing the in vivo immunogenicity of human as well as murine Id-KLH conjugate vaccines. Optimal conditions for Id sulfhydryl pre-reduction were determined, and maleimide Id-KLH conjugates maintained stability and potency even after prolonged storage. Field flow fractionation analysis of Id-KLH particle size revealed that maleimide conjugates were far more uniform in size than glutaraldehyde conjugates. Under increasingly stringent conditions, maleimide Id-KLH vaccines maintained superior efficacy over glutaraldehyde Id-KLH in treating established, disseminated murine lymphoma. More importantly, human maleimide Id-KLH conjugates were consistently superior to glutaraldehyde Id-KLH conjugates in inducing Id-specific antibody and T cell responses. The described methods should be easily adaptable to the production of clinical grade vaccines for human trials in B cell malignancies.

Cisplatin augments cytotoxic T-lymphocyte–mediated antitumor immunity in poorly immunogenic murine lung cancer

OBJECTIVE Many tumors are poorly immunogenic and resistant to cytotoxic T-lymphocyte-mediated cell lysis. Because cisplatin has been demonstrated to increase tumor cell Fas receptor expression, we hypothesized that cisplatin will enhance cytotoxic T-lymphocyte tumor cell killing and augment the antitumor effect of an active immunotherapy strategy in a poorly immunogenic murine lung cancer model. METHODS Lewis lung carcinoma cells were exposed to cisplatin in vitro, and Fas receptor expression and apoptosis in response to an agonistic anti-Fas antibody were quantified using flow cytometry. Wild-type and Fas ligand-deficient mice bearing Lewis lung carcinoma flank tumors were then treated with intraperitoneal cisplatin as well as an intratumoral injection of an adenovirus gene transfer vector encoding CD40 ligand. End points included tumor size, animal survival, and Fas expression (determined using immunofluorescence). Cytotoxicity assays were performed using splenocytes from adenovirus gene transfer vector encoding CD40 ligand-treated animals as effectors and cisplatin-treated Lewis lung carcinoma cells as targets. RESULTS Cisplatin induced heightened expression of Fas receptor on Lewis lung carcinoma cells in vitro and in vivo and enhanced apoptosis in cells exposed to an agonistic anti-Fas antibody. In vivo, the combination of 1 dose of intraperitoneal cisplatin and intratumoral adenovirus gene transfer vector encoding CD40 ligand inhibited tumor growth and prolonged survival compared with adenovirus gene transfer vector encoding CD40 ligand alone, resulting in a higher cure rate. This effect was lost in Fas ligand-deficient mice. Splenocytes from adenovirus gene transfer vector encoding CD40 ligand-treated wild-type mice lysed cisplatin-treated Lewis lung carcinoma cells more efficiently than untreated Lewis lung carcinoma cells, an effect lost in splenocytes from Fas ligand-deficient mice. CONCLUSION Cisplatin augments the antitumor effect of a cytotoxic T-lymphocyte-mediated immunotherapy strategy, resulting in a higher cure rate than seen with immunotherapy alone. This effect is associated with the enhanced ability of cytotoxic T lymphocytes to lyse tumor cells that have been exposed to cisplatin through Fas/Fas ligand interactions.

Anti-CD20-interferon-β fusion protein therapy of murine B cell lymphomas

Type I interferons (IFN&agr;/&bgr;) are cytokines with a broad spectrum of antitumor activities including antiproliferative, proapoptotic, and immunostimulatory effects, and are potentially useful in the treatment of B-cell malignancies and other cancers. To improve antitumor potency and diminish the systemic side effects of IFN, we recently developed anti-CD20-IFN&agr; fusion proteins with in vitro and in vivo efficacy against both mouse and human lymphomas expressing CD20. As IFN&bgr; binds more tightly to the IFN&agr;/&bgr; receptor (IFNAR) and has more potent antitumor activities, we have now constructed an anti-CD20 fusion protein with murine IFN&bgr; (mIFN&bgr;). Anti-CD20-mIFN&bgr; was more potent than recombinant mIFN&bgr; and anti-CD20-mIFN&agr; in inhibiting the proliferation of a mouse B-cell lymphoma expressing human CD20 (38C13-huCD20). Growth inhibition was accompanied by caspase-independent apoptosis and DNA fragmentation. The efficacy of anti-CD20-mIFN&bgr; required the physical linkage of mIFN&bgr; to anti-CD20 antibody. Importantly, anti-CD20-mIFN&bgr; was active against tumor cells expressing low levels of IFNAR (38C13-huCD20 IFNARlo). In vivo, established 38C13-huCD20 tumors were largely insensitive to rituximab or a nontargeted mIFN&bgr; fusion protein, yet treatment with anti-CD20-mIFN&bgr; eradicated 83% of tumors. Anti-CD20-mIFN&bgr; was also more potent in vivo against 38C13-huCD20 than anti-CD20-mIFN&agr;, curing 75% versus 25% of tumors (P=0.001). Importantly, although anti-CD20-mIFN&agr; could not eradicate 38C13-huCD20 IFNARlo tumors, anti-CD20-mIFN&bgr; treatment prolonged survival (P=0.0003), and some animals remained tumor-free. Thus, antibody fusion proteins targeting mIFN&bgr; to tumors show promise as therapeutic agents, especially for use against tumors resistant to the effects of mIFN&agr;.

Intratumoral expression of macrophage-derived chemokine induces CD4+ T cell-independent antitumor immunity in mice.

Macrophage-derived chemokine is chemotactic for a variety of leukocytes, and has been shown to be involved in TH2-mediated cellular immunity. To evaluate the role of this chemokine in tumor immunity in vivo, an adenovirus vector encoding the human macrophage-derived chemokine cDNA (AdMDC) was administered to established murine tumors. Gene transfer with AdMDC significantly inhibited tumor growth and prolonged animal survival. AdMDC was not directly cytotoxic to tumor cells, but splenocytes from animals that received intratumoral AdMDC were able to lyse syngeneic tumor cells, and purified splenic CD8+ cells secreted interferon-&ggr; in a tumor-specific manner. The antitumor activity of AdMDC was lost in mice lacking CD8+ T lymphocytes, but surprisingly, it was preserved in animals lacking CD4+ cells, as was the systemic cytotoxic T lymphocyte response. Systemic NK cells did not play a role in the antitumor immune response induced by AdMDC. Experiments using knockout mice demonstrated that host expression of MHC Class I, but not Class II, IL-4, or IL-12, was necessary for AdMDC to exert its antitumor effect, and immunohistochemistry demonstrated infiltrates of CD8+ and CD86+ cells, but not CD4+ cells in treated tumors. These studies highlight a new function for macrophage-derived chemokine by demonstrating that it possesses in vivo antitumor activity with CD8+ T cells as the effector cells, and interestingly, that the CD4+ cell/MHC II pathway of CD8+ cell activation is not required for the antitumor effects of this chemokine.

Adenovirus Gene Transfer Vectors Inhibit Growth of Lymphatic Tumor Metastases Independent of a Therapeutic Transgene

Adenovirus (Ad) gene transfer vectors traffic to regional lymph nodes (RLNs) after footpad injections in mice, resulting in localized production of interferon gamma (IFN-gamma). With this background, we evaluated the hypothesis that Ad vector administration may inhibit RLN tumor metastasis independent of the transgene in the expression cassette. Tumors of MM48, a cell line with a propensity toward lymphogenous metastasis, were established in the footpads of syngeneic C3H mice, and E1(-)E3(-) Ad vectors encoding no transgene (AdNull) or encoding an irrelevant transgene (AdCD; Escherichia coli cytosine deaminase with no 5-fluorocytosine administration) were administered (10(10) particles) in a peritumoral location. Both vectors suppressed the growth of tumor in the regional (popliteal) lymph node. This effect was localized to the regional, but not distant, lymph nodes (p < 0.05). Heat inactivation of the vector or decreasing the dose of the vector to 10(9) particles did not suppress RLN growth of the tumor when compared with 10(10) particles of active AdNull (p < 0.05 and p < 0.01, respectively). The ability of an E1(-)E4(-) vector expressing beta-galactosidase (AdRSVbetagal.11) to suppress RLN tumor growth showed that the E4 region of the Ad vector was not responsible for the effect. Blocking either IFN-gamma or natural killer (NK) cells with systemic antibody treatment in immunocompetent mice allowed rapid growth of RLN metastases despite Ad vector administration, and Ad vector injection into the footpads of tumor-free mice induced the accumulation of NK cells in the RLN. These data demonstrate that, in a metastatic murine tumor model, a low dose (10(10) particles) of replication-deficient Ad vectors inhibits RLN metastases independent of a therapeutic transgene, an effect that is mediated, at least in part, by IFN-gamma and NK cells.