Brent A. Hanks

Re-engineered CD40 receptor enables potent pharmacological activation of dendritic-cell cancer vaccines in vivo

Modest clinical outcomes of dendritic-cell (DC) vaccine trials call for the refinement of DC vaccine design. Although many potential antigens have been identified, development of methods to enhance antigen presentation by DCs has lagged. We have engineered a potent, drug-inducible CD40 (iCD40) receptor that permits temporally controlled, lymphoid-localized, DC-specific activation. iCD40 is comprised of a membrane-localized cytoplasmic domain of CD40 fused to drug-binding domains. This allows it to respond to a lipid-permeable, high-affinity dimerizer drug while circumventing ectodomain-dependent negative-feedback mechanisms. These modifications permit prolonged activation of iCD40-expressing DCs in vivo, resulting in more potent CD8+ T-cell effector responses, including the eradication of previously established solid tumors, relative to activation of DCs ex vivo (P < 0.01), typical of most clinical DC protocols. In addition, iCD40-mediated DC activation exceeded that achieved by stimulating the full-length, endogenous CD40 receptor both in vitro and in vivo. Because iCD40 is insulated from the extracellular environment and can be activated within the context of an immunological synapse, iCD40-expressing DCs have a prolonged lifespan and should lead to more potent vaccines, perhaps even in immune-compromised patients.

Enhanced Activation of Human Dendritic Cells by Inducible CD40 and Toll-like Receptor-4 Ligation

Despite the potency of dendritic cells (DC) as antigen-presenting cells for priming adaptive immunity, DC-based cancer vaccines have been largely insufficient to effectively reduce tumor burden or prevent tumor progression in most patients. To enhance DC-based vaccines, we used the combination of a synthetic ligand-inducible CD40 receptor (iCD40) along with Toll-like receptor-4 (TLR-4) ligation in human monocyte-derived DCs. The iCD40 receptor permits targeted, reversible activation of CD40 in vivo, potentially bypassing the essential role of CD4(+) T cells for activation of DCs. As a rigorous preclinical study of this approach, we evaluated key parameters of DC activation and function. Whereas neither iCD40 nor TLR-4 signaling alone led to high levels of interleukin (IL)-12p70 and IL-6, using iCD40 in combination with lipopolysaccharide (LPS) or monophosphoryl lipid A led to strongly synergistic production of both. Furthermore, this approach led to high expression of DC maturation markers, epitope-specific CTL and T helper 1 responses, as well as DC migration in vitro and in vivo. Moreover, use of iCD40-modified and LPS-stimulated DCs led to targeted expansion of autologous T cells against tumor-associated antigens, including prostate-specific membrane antigen, and elimination of preestablished tumors, supporting this technology as a potent strategy for DC-based cancer immunotherapy.

Type III TGF-β receptor downregulation generates an immunotolerant tumor microenvironment

Cancers subvert the host immune system to facilitate disease progression. These evolved immunosuppressive mechanisms are also implicated in circumventing immunotherapeutic strategies. Emerging data indicate that local tumor-associated DC populations exhibit tolerogenic features by promoting Treg development; however, the mechanisms by which tumors manipulate DC and Treg function in the tumor microenvironment remain unclear. Type III TGF-β receptor (TGFBR3) and its shed extracellular domain (sTGFBR3) regulate TGF-β signaling and maintain epithelial homeostasis, with loss of TGFBR3 expression promoting progression early in breast cancer development. Using murine models of breast cancer and melanoma, we elucidated a tumor immunoevasion mechanism whereby loss of tumor-expressed TGFBR3/sTGFBR3 enhanced TGF-β signaling within locoregional DC populations and upregulated both the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) in plasmacytoid DCs and the CCL22 chemokine in myeloid DCs. Alterations in these DC populations mediated Treg infiltration and the suppression of antitumor immunity. Our findings provide mechanistic support for using TGF-β inhibitors to enhance the efficacy of tumor immunotherapy, indicate that sTGFBR3 levels could serve as a predictive immunotherapy biomarker, and expand the mechanisms by which TGFBR3 suppresses cancer progression to include effects on the tumor immune microenvironment.

Identifying baseline immune-related biomarkers to predict clinical outcome of immunotherapy

As cancer strikes, individuals vary not only in terms of factors that contribute to its occurrence and development, but as importantly, in their capacity to respond to treatment. While exciting new therapeutic options that mobilize the immune system against cancer have led to breakthroughs for a variety of malignancies, success is limited to a subset of patients. Pre-existing immunological features of both the host and the tumor may contribute to how patients will eventually fare with immunotherapy. A broad understanding of baseline immunity, both in the periphery and in the tumor microenvironment, is needed in order to fully realize the potential of cancer immunotherapy. Such interrogation of the tumor, blood, and host immune parameters prior to treatment is expected to identify biomarkers predictive of clinical outcome as well as to elucidate why some patients fail to respond to immunotherapy. To approach these opportunities for progress, the Society for Immunotherapy of Cancer (SITC) reconvened the Immune Biomarkers Task Force. Comprised of an international multidisciplinary panel of experts, Working Group 4 sought to make recommendations that focus on the complexity of the tumor microenvironment, with its diversity of immune genes, proteins, cells, and pathways naturally present at baseline and in circulation, and novel tools to aid in such broad analyses.

Rapid complete response of metastatic melanoma in a patient undergoing ipilimumab immunotherapy in the setting of active ulcerative colitis

While blockade of the cytotoxic T-lymphocyte antigen-4 (CTLA-4) T cell regulatory receptor has become a commonly utilized strategy in the management of advanced melanoma, many questions remain regarding the use of this agent in patient populations with autoimmune disease. We present a case involving the treatment of a patient with stage IV melanoma and ulcerative colitis (UC) with anti-CTLA-4 antibody immunotherapy. Upon initial treatment, the patient developed grade III colitis requiring tumor necrosis factor-alpha (TNF-α) blocking antibody therapy, however re-treatment with anti-CTLA-4 antibody following a total colectomy resulted in a rapid complete response accompanied by the development of a tracheobronchitis, a previously described extra-intestinal manifestation of UC. This case contributes to the evolving literature on the use of checkpoint inhibitors in patients also suffering from autoimmune disease, supports future clinical trials investigating the use of these agents in patients with autoimmune diseases, and suggests that an understanding of the specific molecular pathways involved in a patient’s autoimmune pathology may provide insight into the development of more effective novel combinatorial immunotherapeutic strategies.

Melanoma-Derived Wnt5a Promotes Local Dendritic-Cell Expression of IDO and Immunotolerance: Opportunities for Pharmacologic Enhancement of Immunotherapy

Melanomas produce Wnt5a, which promotes the ability of local DCs to drive regulatory T-cell expansion and to generate an immunosuppressive tumor microenvironment. Targeting this system could lead to the development of novel immunotherapeutic strategies. The β-catenin signaling pathway has been demonstrated to promote the development of a tolerogenic dendritic cell (DC) population capable of driving regulatory T-cell (Treg) differentiation. Further studies have implicated tolerogenic DCs in promoting carcinogenesis in preclinical models. The molecular mechanisms underlying the establishment of immune tolerance by this DC population are poorly understood, and the methods by which developing cancers can co-opt this pathway to subvert immune surveillance are currently unknown. This work demonstrates that melanoma-derived Wnt5a ligand upregulates the durable expression and activity of the indoleamine 2,3-dioxygenase-1 (IDO) enzyme by local DCs in a manner that depends upon the β-catenin signaling pathway. These data indicate that Wnt5a-conditioned DCs promote the differentiation of Tregs in an IDO-dependent manner, and that this process serves to suppress melanoma immune surveillance. We further show that the genetic silencing of the PORCN membrane–bound O-acyl transferase, which is necessary for melanoma Wnt ligand secretion, enhances antitumor T-cell immunity, and that the pharmacologic inhibition of this enzyme synergistically suppresses melanoma progression when combined with anti–CTLA-4 antibody therapy. Finally, our data suggest that β-catenin signaling activity, based on a target gene expression profile that includes IDO in human sentinel lymph node–derived DCs, is associated with melanoma disease burden and diminished progression-free survival. This work implicates the Wnt–β-catenin signaling pathway as a novel therapeutic target in the melanoma immune microenvironment and demonstrates the potential impact of manipulating DC function as a strategy for optimizing tumor immunotherapy. Cancer Immunol Res; 3(9); 1082–95. ©2015 AACR.

Genetic risk analysis of a patient with fulminant autoimmune type 1 diabetes mellitus secondary to combination ipilimumab and nivolumab immunotherapy

BackgroundCheckpoint inhibitor immunotherapy is becoming an effective treatment modality for an increasing number of malignancies. As a result, autoinflammatory side-effects are also being observed more commonly in the clinic. We are currently unable to predict which patients will develop more severe toxicities associated with these treatment regimens.Case presentationWe present a patient with stage IV melanoma that developed rapid onset autoimmune type 1 diabetes (T1D) in response to combination ipilimumab and nivolumab immunotherapy. At the time of the patient’s presentation with diabetes ketoacidosis, a confirmed anti-GAD antibody seroconversion was noted. Longer-term follow-up of this patient has demonstrated a durable complete response based on PET CT imaging along with a persistently undetectable C-peptide level. Single nucleotide polymorphism gene sequencing and HLA risk allele analysis has revealed the patient to lack any established genetic predisposition to the development of autoimmune T1D.ConclusionsWhile larger studies are necessary to better understand the role of genetic risk factors for the development of autoimmune toxicities in those patients undergoing checkpoint inhibitor immunotherapy, these results suggest that pre-screening patients for known T1D risk alleles may not be indicated. Additional investigation is needed to determine whether an approach such as T cell receptor clonotypic analysis to identify the presence of autoreactive T cell clones may be an effective approach for predicting which patients are at risk for the development of autoinflammatory toxicities while undergoing checkpoint inhibitor immunotherapy.

Improved time to progression for transarterial chemoembolization compared with transarterial embolization for patients with unresectable hepatocellular carcinoma.

BACKGROUND Embolizing branches of the hepatic artery lengthens survival for patients with unresectable hepatocellular carcinoma (HCC), but the benefit of combining chemotherapy with the embolizing particles remains controversial. METHODS A retrospective review was undertaken of sequential patients with advanced HCC undergoing embolization in the past 10 years at 2 neighboring institutions and with 2 years of follow-up data. TACE was generally performed with doxorubicin plus mitomycin C. RESULTS One hundred twenty-four patients were included; 77 received TACE and 47 received TAE. On multivariable analysis stratified by institution, type of embolization and CLIP score significantly predicted PFS and time to progression (TTP), whereas CLIP score and AFP independently predicted overall survival (OS). TACE significantly prolonged PFS and TTP (P = .0004 and P = .001, respectively), but not OS (P = .83). CONCLUSIONS The addition of chemotherapy to TAE prolongs PFS and TTP. Future efforts should focus on adjunctive therapies after the embolization to increase survival.

Early Carcinogenesis Involves the Establishment of Immune Privilege via Intrinsic and Extrinsic Regulation of Indoleamine 2,3-dioxygenase-1: Translational Implications in Cancer Immunotherapy.

Although prolonged genetic pressure has been conjectured to be necessary for the eventual development of tumor immune evasion mechanisms, recent work is demonstrating that early genetic mutations are capable of moonlighting as both intrinsic and extrinsic modulators of the tumor immune microenvironment. The indoleamine 2,3-dioxygenase-1 (IDO) immunoregulatory enzyme is emerging as a key player in tumor-mediated immune tolerance. While loss of the tumor suppressor, BIN-1, and the over-expression of cyclooxygenase-2 have been implicated in intrinsic regulation of IDO, recent findings have demonstrated the loss of TβRIII and the upregulation of Wnt5a by developing cancers to play a role in the extrinsic control of IDO activity by local dendritic cell populations residing within tumor and tumor-draining lymph node tissues. Together, these genetic changes are capable of modulating paracrine signaling pathways in the early stages of carcinogenesis to establish a site of immune privilege by promoting the differentiation and activation of local regulatory T cells. Additional investigation of these immune evasion pathways promises to provide opportunities for the development of novel strategies to synergistically enhance the efficacy of the evolving class of T cell-targeted “checkpoint” inhibitors.

Isolated recto-sigmoid colitis: a new imaging pattern of ipilimumab-associated colitis.

AbstractPurposeThe purpose of this study is to describe typical CT findings and distinct imaging patterns of ipilimumab-associated colitis in immunotherapeutic treatment of melanoma.Materials and methodsThis HIPAA-compliant retrospective study included 86 patients with melanoma imaged with CT or PET/CT of the abdomen and pelvis during or shortly after administration of ipilimumab. Twelve of 86 patients (14%) developed symptoms of colitis and underwent CT imaging of the abdomen and pelvis while symptomatic. Two radiologists reviewed CT images to evaluate for the presence of CT findings of colitis including mesenteric vessel engorgement, pericolonic inflammatory change, hyperenhancement of colonic mucosa, colonic wall thickening, fluid-filled colonic distension, pneumoperitoneum, pneumatosis, and diverticulosis in the inflamed segment of colon. One nuclear medicine radiologist reviewed PET images for abnormally increased FDG uptake in the colon. The diagnosis of ipilimumab-associated colitis was made based on clinical presentation, imaging findings, and laboratory data.ResultsCommon CT findings of ipilimumab-associated colitis included colonic mucosal hyperenhancement (10/12 [83%]), mesenteric vessel engorgement (9/12 [75.0%]), colonic wall thickening (9/12 [75%]), and pericolonic fat stranding (2/12 [16%]). No patient developed pneumatosis or pneumoperitoneum. Diffuse colitis was present in 4/12 (33%) patients. Segmental colitis with associated diverticulosis (was present in 2/12 (17%) patients). A third pattern, isolated recto-sigmoid colitis without diverticulosis, was observed in 6/12 (50%) patients. All patients with colitis demonstrated recto-sigmoid involvement.ConclusionsA third radiologic pattern of ipilimumab-associated colitis was observed in this study: isolated recto-sigmoid colitis without diverticulosis. All patterns of ipilimumab-associated colitis include recto-sigmoid involvement.