Liposomal Phenylephrine Nanoparticles Enhance the Antitumor Activity of Intratumoral Chemotherapy in a Preclinical Model of Melanoma

Intratumoral injection of anticancer agents has limited efficacy and is not routinely used for most cancers. In this study, we aimed to improve the efficacy of intratumoral chemotherapy using a novel approach comprising peri-tumoral injection of sustained-release liposomal nanoparticles containing phenylephrine, which is a potent vasoconstrictor. Using a preclinical model of melanoma, we have previously shown that systemically administered (intravenous) phenylephrine could transiently shunt blood flow to the tumor at the time of drug delivery, which in turn improved antitumor responses. This approach was called dynamic control of tumor-associated vessels. Herein, we used liposomal phenylephrine nanoparticles as a "local" dynamic control strategy for the B16 melanoma. Local dynamic control was shown to increase the retention and exposure time of tumors to intratumorally injected chemotherapy (melphalan). C57BL/6 mice bearing B16 tumors were treated with intratumoral melphalan and peri-tumoral injection of sustained-release liposomal phenylephrine nanoparticles (i.e., the local dynamic control protocol). These mice had statistically significantly improved antitumor responses compared to melphalan alone (p = 0.0011), whereby 58.3% obtained long-term complete clinical response. Our novel approach of local dynamic control demonstrated significantly enhanced antitumor efficacy and is the subject of future clinical trials being designed by our group.

Expression of c-erb-B2 oncoprotein as a neoantigen strategy to repurpose anti-neu antibody therapy in a model of melanoma

In this study, we tested a novel approach of "repurposing" a biomarker typically associated with breast cancer for use in melanoma. HER2/neu is a well characterized biomarker in breast cancer for which effective anti-HER2/neu therapies are readily available. We constructed a lentivirus encoding c-erb-B2 (the animal homolog to HER2/neu). This was used to transfect B16 melanoma in vitro for use in an orthotopic preclinical mouse model, which resulted in expression of c-erb-B2 as a neoantigen target for anti-c-erb-B2 monoclonal antibody (7.16.4). The c-erb-B2-expressing melanoma was designated B16/neu. 7.16.4 produced statistically significant in vivo anti-tumor responses against B16/neu. This effect was mediated by NK-cell antibody-dependent cell-mediated cytotoxicity. To further model human melanoma (which expresses <5% HER2/neu), our c-erb-B2 encoding lentivirus was used to inoculate naïve (wild-type) B16 tumors in vivo , resulting in successful c-erb-B2 expression. When combined with 7.16.4, anti-tumor responses were again demonstrated where approximately 40% of mice treated with c-erb-B2 lentivirus and 7.16.4 achieved complete clinical response and long-term survival. For the first time, we demonstrated a novel strategy to repurpose c-erb-B2 as a neoantigen target for melanoma. Our findings are particularly significant in the contemporary setting where newer anti-HER2/neu antibody-drug candidates have shown increased efficacy.

Th17-inducing dendritic cell vaccines stimulate effective CD4 T cell-dependent antitumor immunity in ovarian cancer that overcomes resistance to immune checkpoint blockade

BACKGROUND

Ovarian cancer (OC), a highly lethal cancer in women, has a 48% 5-year overall survival rate. Prior studies link the presence of IL-17 and Th17 T cells in the tumor microenvironment to improved survival in OC patients. To determine if Th17-inducing vaccines are therapeutically effective in OC, we created a murine model of Th17-inducing dendritic cell (DC) (Th17-DC) vaccination generated by stimulating IL-15 while blocking p38 MAPK in bone marrow-derived DCs, followed by antigen pulsing.

METHODS

ID8 tumor cells were injected intraperitoneally into mice. Mice were treated with Th17-DC or conventional DC (cDC) vaccine alone or with immune checkpoint blockade (ICB). Systemic immunity, tumor associated immunity, tumor size and survival were examined using a variety of experimental strategies.

RESULTS

Th17-DC vaccines increased Th17 T cells in the tumor microenvironment, reshaped the myeloid microenvironment, and improved mouse survival compared with cDC vaccines. ICB had limited efficacy in OC, but Th17-inducing DC vaccination sensitized it to anti-PD-1 ICB, resulting in durable progression-free survival by overcoming IL-10-mediated resistance. Th17-DC vaccine efficacy, alone or with ICB, was mediated by CD4 T cells, but not CD8 T cells.

CONCLUSIONS

These findings emphasize using biologically relevant immune modifiers, like Th17-DC vaccines, in OC treatment to reshape the tumor microenvironment and enhance clinical responses to ICB therapy.

Protein kinase Cι mediates immunosuppression in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the most prevalent form of non–small cell lung cancer (NSCLC) and a leading cause of cancer death. Immune checkpoint inhibitors (ICIs) of programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) signaling induce tumor regressions in a subset of LUAD, but many LUAD tumors exhibit resistance to ICI therapy. Here, we identified Prkci as a major determinant of response to ICI in a syngeneic mouse model of oncogenic mutant Kras / Trp53 loss (KP)–driven LUAD. Protein kinase Cι (PKCι)–dependent KP tumors exhibited resistance to anti–PD-1 antibody therapy (α-PD-1), whereas KP tumors in which Prkci was genetically deleted (KPI tumors) were highly responsive. Prkci- dependent resistance to α-PD-1 was characterized by enhanced infiltration of myeloid-derived suppressor cells (MDSCs) and decreased infiltration of CD8 + T cells in response to α-PD-1. Mechanistically, Prkci regulated YAP1-dependent expression of Cxcl5 , which served to attract MDSCs to KP tumors. The PKCι inhibitor auranofin inhibited KP tumor growth and sensitized these tumors to α-PD-1, whereas expression of either Prkci or its downstream effector Cxcl5 in KPI tumors induced intratumoral infiltration of MDSCs and resistance to α-PD-1. PRKCI expression in tumors of patients with LUAD correlated with genomic signatures indicative of high YAP1-mediated transcription, elevated MDSC infiltration and low CD8 + T cell infiltration, and with elevated CXCL5 / 6 expression. Last, PKCι-YAP1 signaling was a biomarker associated with poor response to ICI in patients with LUAD. Our data indicate that immunosuppressive PKCι-YAP1-CXCL5 signaling is a key determinant of response to ICI, and pharmacologic inhibition of PKCι may improve therapeutic response to ICI in patients with LUAD.

Folate Receptor Alpha Peptide Vaccine Generates Immunity in Breast and Ovarian Cancer Patients

Purpose: Folate receptor alpha (FR) is overexpressed in several cancers. Endogenous immunity to the FR has been demonstrated in patients and suggests the feasibility of targeting FR with vaccine or other immune therapies. CD4 helper T cells are central to the development of coordinated immunity, and prior work shows their importance in protecting against relapse. Our previous identification of degenerate HLA-class II epitopes from human FR led to the development of a broad coverage epitope pool potentially useful in augmenting antigen-specific immune responses in most patients.Patients and Methods: We conducted a phase I clinical trial testing safety and immunogenicity of this vaccine, enrolling patients with ovarian cancer or breast cancer who completed conventional treatment and who showed no evidence of disease. Patients were initially treated with low-dose cyclophosphamide and then vaccinated 6 times, monthly. Immunity and safety were examined during the vaccine period and up to 1 year later.Results: Vaccination was well tolerated in all patients. Vaccine elicited or augmented immunity in more than 90% of patients examined. Unlike recall immunity to tetanus toxoid (TT), FR T-cell responses developed slowly over the course of vaccination with a median time to maximal immunity in 5 months. Despite slow development of immunity, responsiveness appeared to persist for at least 12 months.Conclusions: The results demonstrate that it is safe to augment immunity to the FR tumor antigen, and the developed vaccine is testable for therapeutic activity in most patients whose tumors express FR, regardless of HLA genotype. Clin Cancer Res; 24(13); 3014-25. ©2018 AACR.

Folate Receptor Alpha Peptide Vaccine Generates Immunity in Breast and Ovarian Cancer Patients

Purpose: Folate receptor alpha (FR) is overexpressed in several cancers. Endogenous immunity to the FR has been demonstrated in patients and suggests the feasibility of targeting FR with vaccine or other immune therapies. CD4 helper T cells are central to the development of coordinated immunity, and prior work shows their importance in protecting against relapse. Our previous identification of degenerate HLA-class II epitopes from human FR led to the development of a broad coverage epitope pool potentially useful in augmenting antigen-specific immune responses in most patients.Patients and Methods: We conducted a phase I clinical trial testing safety and immunogenicity of this vaccine, enrolling patients with ovarian cancer or breast cancer who completed conventional treatment and who showed no evidence of disease. Patients were initially treated with low-dose cyclophosphamide and then vaccinated 6 times, monthly. Immunity and safety were examined during the vaccine period and up to 1 year later.Results: Vaccination was well tolerated in all patients. Vaccine elicited or augmented immunity in more than 90% of patients examined. Unlike recall immunity to tetanus toxoid (TT), FR T-cell responses developed slowly over the course of vaccination with a median time to maximal immunity in 5 months. Despite slow development of immunity, responsiveness appeared to persist for at least 12 months.Conclusions: The results demonstrate that it is safe to augment immunity to the FR tumor antigen, and the developed vaccine is testable for therapeutic activity in most patients whose tumors express FR, regardless of HLA genotype. Clin Cancer Res; 24(13); 3014-25. ©2018 AACR.

IL10 Release upon PD-1 Blockade Sustains Immunosuppression in Ovarian Cancer

Ligation of programmed cell death-1 (PD-1) in the tumor microenvironment is known to inhibit effective adaptive antitumor immunity. Blockade of PD-1 in humans has resulted in impressive, durable regression responses in select tumor types. However, durable responses have been elusive in ovarian cancer patients. PD-1 was recently shown to be expressed on and thereby impair the functions of tumor-infiltrating murine and human myeloid dendritic cells (TIDC) in ovarian cancer. In the present work, we characterize the regulation of PD-1 expression and the effects of PD-1 blockade on TIDC. Treatment of TIDC and bone marrow-derived dendritic cells (DC) with IL10 led to increased PD-1 expression. Both groups of DCs also responded to PD-1 blockade by increasing production of IL10. Similarly, treatment of ovarian tumor-bearing mice with PD-1 blocking antibody resulted in an increase in IL10 levels in both serum and ascites. While PD-1 blockade or IL10 neutralization as monotherapies were inefficient, combination of these two led to improved survival and delayed tumor growth; this was accompanied by augmented antitumor T- and B-cell responses and decreased infiltration of immunosuppressive MDSC. Taken together, our findings implicate compensatory release of IL10 as one of the adaptive resistance mechanisms that undermine the efficacy of anti-PD-1 (or anti-PD-L1) monotherapies and prompt further studies aimed at identifying such resistance mechanisms. Cancer Res; 77(23); 6667-78. ©2017 AACR.

Improved Survival of HER2+ Breast Cancer Patients Treated with Trastuzumab and Chemotherapy Is Associated with Host Antibody Immunity against the HER2 Intracellular Domain

The addition of trastuzumab to chemotherapy extends survival among patients with HER2(+) breast cancer. Prior work showed that trastuzumab and chemotherapy augments HER2 extracellular domain (ECD)-specific antibodies. The current study investigated whether combination therapy induced immune responses beyond HER2-ECD and, importantly, whether those immune responses were associated with survival. Pretreatment and posttreatment sera were obtained from 48 women with metastatic HER2(+) breast cancer on NCCTG (now Alliance for Clinical Trials in Oncology) studies, N0337 and N983252. IgG to HER2 intracellular domain (ICD), HER2-ECD, p53, IGFBP2, CEA, and tetanus toxoid were examined. Sera from 25 age-matched controls and 26 surgically resected HER2(+) patients were also examined. Prior to therapy, some patients with metastatic disease had elevated antibodies to IGFBP2, p53, HER2-ICD, HER2-ECD, and CEA, but not to tetanus toxin, relative to controls and surgically resected patients. Treatment augmented antibody responses to HER2-ICD in 69% of metastatic patients, which was highly associated with improved progression-free survival (PFS; HR = 0.5, P = 0.0042) and overall survival (OS; HR = 0.7, P = 0.038). Augmented antibody responses to HER2-ICD also correlated (P = 0.03) with increased antibody responses to CEA, IGFBP2, and p53, indicating that treatment induces epitope spreading. Paradoxically, patients who already had high preexisting immunity to HER2-ICD did not respond to therapy with increased antibodies to HER2-ICD and demonstrated poorer PFS (HR = 1.6, P < 0.0001) and OS (HR = 1.4, P = 0.0006). Overall, the findings further demonstrate the importance of the adaptive immune system in the efficacy of trastuzumab-containing regimens. Cancer Res; 76(13); 3702-10. ©2016 AACR.

Abstract B66: Blockade of PD-1 signaling in tumor-associated dendritic cells results in compensatory IL-10 release maintaining immune suppression in ovarian cancer microenvironments

PD-1 and PD-L1 form a major inhibitory axis that acts to suppress tumor-rejecting effector responses. In addition to its expression and inhibitory functions in T and B cells, PD-1 has also been shown to be expressed on and hence impact the functions of cells of innate arm, such as dendritic cells (DCs), primarily at the tumor site but not in the periphery. Our aim in this study was to identify tumor-associated factor(s) responsible for PD-1 regulation on DCs and investigate how DCs in the tumor microenvironment respond to anti-PD-1-based immunotherapy. Both bone marrow-derived dendritic cells (BMDCs) as well as murine ovarian tumor ascites-derived DCs were used in the studies. Using in vitro cultures, we show that the cytokine IL-10; which is expressed in abundance in many malignancies including ovarian cancer, is potent regulator of PD-1 expression on DCs. Based on inhibition and siRNA knockdown studies; we show that IL-10 mediated PD-1 expression depends on STAT3 activation. Treatment of DCs with IL-10 also led to an increase in expression of PD-L1 on surface of DCs as well as an increase in release of soluble PD-L1. Antibody-mediated blockade of PD-1 on DCs led to greatly increased production of IL-10 (&gt; 4 fold) in cultures in vitro. Furthermore, treatment of tumor bearing mice with anti-PD-1 antibody led to a significant increase of IL-10 in ascites (&gt; 6 fold) and periphery (&gt; 4 fold). This compensatory release of IL-10 correlated with a further increase in PD-1 expression on DCs both in vitro and in vivo. In in vivo studies, while the blockade of PD-1 or IL-10 neutralization as monotherapy were ineffective, blockade of PD-1 and IL-10 neutralization as combination therapy augmented the anti-tumor response in ovarian tumor bearing mice; leading to a decrease in tumor growth and a significant increase in survival. These results show that the IL-10 and PD-1 pathways intersect with DCs in the tumor microenvironment. PD-1 blockade on DCs leads to compensatory release of IL-10 resulting in the maintenance of immunosuppression, and a combination regimen of PD-1 blockade and IL-10 neutralization has therapeutic benefit in ovarian tumors. These results serve as catalyst to explore the feasibility/efficacy of exploiting these targets in clinical settings for treatment of human ovarian cancer.

Citation Format: Purushottam Lamichhane, Lavakumar Karyampudi, Barath Shreeder, James Krempski, Deborah Bahr, Matthew Block, Keith Knutson. Blockade of PD-1 signaling in tumor-associated dendritic cells results in compensatory IL-10 release maintaining immune suppression in ovarian cancer microenvironments. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B66.

PD-1 and IL-10: partners in crime against anti-tumor immunity in ovarian cancer. (TUM9P.1011)

PD-1: PD-L1 is a major inhibitory axis that acts to suppress tumor-rejecting effector responses. In addition to its expression and inhibitory functions in T and B cells; PD-1 has also been shown to be expressed on and thereby impact the functions of cells of innate arm such as dendritic cells (DCs) primarily at the tumor site but not in the periphery. We show here that one of the culprits in the tumor microenvironment responsible for enhancing PD-1 expression on the tumor-associated DCs is the cytokine IL-10; which is expressed in abundance in many malignancies including ovarian cancer. Based on inhibition and knockdown studies, we show that IL-10 mediated PD-1 expression depends on STAT3 activation. Using murine model of ovarian carcinoma (ID8), we show that tumor-associated DCs express not only high levels of PD-1 on the surface but also have increased expression of STAT-3 and p-STAT3 compared to splenic DCs. Blockade of PD-1 on DCs led to increased production of IL-10 which correlated with a further increase in PD-1 expression. In in vivo studies, blockade of PD-1 and IL-10 neutralization as combination therapy augmented the anti-tumor response in ID8 ovarian tumor bearing mice; leading to a decrease in tumor mass and a significant increase in survival. These results show that IL-10 and PD-1 pathway intersect in DCs in theTME hence making them attractive targets for therapy of ovarian cancer.

Accumulation of memory precursor CD8 T cells in regressing tumors following combination therapy with vaccine and anti-PD-1 antibody

Immunosuppression in the tumor microenvironment blunts vaccine-induced immune effectors. PD-1/B7-H1 is an important inhibitory axis in the tumor microenvironment. Our goal in this study was to determine the effect of blocking this inhibitory axis during and following vaccination against breast cancer. We observed that using anti-PD-1 antibody and a multipeptide vaccine (consisting of immunogenic peptides derived from breast cancer antigens, neu, legumain, and β-catenin) as a combination therapy regimen for the treatment of breast cancer-bearing mice prolonged the vaccine-induced progression-free survival period. This prolonged survival was associated with increase in number of Tc1 and Tc2 CD8 T cells with memory precursor phenotype, CD27+IL-7RhiT-betlo, and decrease in number of PD-1+ dendritic cells (DC) in regressing tumors and enhanced antigen reactivity of tumor-infiltrating CD8 T cells. It was also observed that blockade of PD-1 on tumor DCs enhanced IL-7R expression on CD8 T cells. Taken together, our results suggest that PD-1 blockade enhances breast cancer vaccine efficacy by altering both CD8 T cell and DC components of the tumor microenvironment. Given the recent success of anti-PD-1 monotherapy, our results are encouraging for developing combination therapies for the treatment of patients with cancer in which anti-PD-1 monotherapy alone may be ineffective (i.e., PD-L1-negative tumors).