Immune-Stimulatory Effects of Rapamycin Are Mediated by Stimulation of Antitumor γδ T Cells

The FDA-approved mTOR inhibitor rapamycin mediates important immune effects, but its contributions to the anticancer effects of the drug are unclear. Here we report evidence that rapamycin-mediated cancer protection relies upon stimulation of γδ T cells. In a well-established mouse model of carcinogen and inflammation-driven skin carcinogenesis, IFNγ recruited γδ TCRmid T cells to the epidermis where rapamycin boosted their perforin-dependent antitumor properties. These antitumor cells were mostly Vγ5-Vγ4-Vγ1- in phenotype. IFNγ signals were required in both hematopoietic and nonhematopoietic cells for rapamycin to optimally promote epidermal infiltration of γδ TCRmid T cells, as mediated by CXCR3-CXCL10 interactions, along with the antitumor effects of these cells. In mouse xenograft models of human squamous cell carcinoma, rapamycin improved human γδ T-cell-mediated cancer cell killing. Our results identify immune mechanisms for the cancer prevention and treatment properties of rapamycin, challenging the paradigm that mTOR inhibition acts primarily by direct action on tumor cells. Cancer Res; 76(20); 5970-82. ©2016 AACR.

Biphasic Rapamycin Effects in Lymphoma and Carcinoma Treatment

mTOR drives tumor growth but also supports T-cell function, rendering the applications of mTOR inhibitors complex especially in T-cell malignancies. Here, we studied the effects of the mTOR inhibitor rapamycin in mouse EL4 T-cell lymphoma. Typical pharmacologic rapamycin (1-8 mg/kg) significantly reduced tumor burden via direct suppression of tumor cell proliferation and improved survival in EL4 challenge independent of antitumor immunity. Denileukin diftitox (DD)-mediated depletion of regulatory T cells significantly slowed EL4 growth in vivo in a T-cell-dependent fashion. However, typical rapamycin inhibited T-cell activation and tumor infiltration in vivo and failed to boost DD treatment effects. Low-dose (LD) rapamycin (75 μg/kg) increased potentially beneficial CD44hiCD62L⁺ CD8⁺ central memory T cells in EL4 challenge, but without clinical benefit. LD rapamycin significantly enhanced DD treatment efficacy, but DD plus LD rapamycin treatment effects were independent of antitumor immunity. Instead, rapamycin upregulated EL4 IL2 receptor in vitro and in vivo, facilitating direct DD tumor cell killing. LD rapamycin augmented DD efficacy against B16 melanoma and a human B-cell lymphoma, but not against human Jurkat T-cell lymphoma or ID8agg ovarian cancer cells. Treatment effects correlated with IL2R expression, but mechanisms in some tumors were not fully defined. Overall, our data define a distinct, biphasic mechanisms of action of mTOR inhibition at doses that are clinically exploitable, including in T-cell lymphomas. Cancer Res; 77(2); 520-31. ©2016 AACR.

Tumor Cell-Independent Estrogen Signaling Drives Disease Progression through Mobilization of Myeloid-Derived Suppressor Cells

The role of estrogens in antitumor immunity remains poorly understood. Here, we show that estrogen signaling accelerates the progression of different estrogen-insensitive tumor models by contributing to deregulated myelopoiesis by both driving the mobilization of myeloid-derived suppressor cells (MDSC) and enhancing their intrinsic immunosuppressive activity in vivo Differences in tumor growth are dependent on blunted antitumor immunity and, correspondingly, disappear in immunodeficient hosts and upon MDSC depletion. Mechanistically, estrogen receptor alpha activates the STAT3 pathway in human and mouse bone marrow myeloid precursors by enhancing JAK2 and SRC activity. Therefore, estrogen signaling is a crucial mechanism underlying pathologic myelopoiesis in cancer. Our work suggests that new antiestrogen drugs that have no agonistic effects may have benefits in a wide range of cancers, independently of the expression of estrogen receptors in tumor cells, and may synergize with immunotherapies to significantly extend survival.

SIGNIFICANCE

Ablating estrogenic activity delays malignant progression independently of the tumor cell responsiveness, owing to a decrease in the mobilization and immunosuppressive activity of MDSCs, which boosts T-cell-dependent antitumor immunity. Our results provide a mechanistic rationale to block estrogen signaling with newer antagonists to boost the effectiveness of anticancer immunotherapies. Cancer Discov; 7(1); 72-85. ©2016 AACR.See related commentary by Welte et al., p. 17This article is highlighted in the In This Issue feature, p. 1.

Tumor-Intrinsic PD-L1 Signals Regulate Cell Growth, Pathogenesis, and Autophagy in Ovarian Cancer and Melanoma

PD-L1 antibodies produce efficacious clinical responses in diverse human cancers, but the basis for their effects remains unclear, leaving a gap in the understanding of how to rationally leverage therapeutic activity. PD-L1 is widely expressed in tumor cells, but its contributions to tumor pathogenicity are incompletely understood. In this study, we evaluated the hypothesis that PD-L1 exerts tumor cell-intrinsic signals that are critical for pathogenesis. Using RNAi methodology, we attenuated PD-L1 in the murine ovarian cell line ID8agg and the melanoma cell line B16 (termed PD-L1^lo cells), which express basal PD-L1. We observed that PD-L1^lo cells proliferated more weakly than control cells in vitro As expected, PD-L1^lo cells formed tumors in immunocompetent mice relatively more slowly, but unexpectedly, they also formed tumors more slowly in immunodeficient NSG mice. RNA sequencing analysis identified a number of genes involved in autophagy and mTOR signaling that were affected by PD-L1 expression. In support of a functional role, PD-L1 attenuation augmented autophagy and blunted the ability of autophagy inhibitors to limit proliferation in vitro and in vivo in NSG mice. PD-L1 attenuation also reduced mTORC1 activity and augmented the antiproliferative effects of the mTORC1 inhibitor rapamycin. PD-L1^lo cells were also relatively deficient in metastasis to the lung, and we found that anti-PD-L1 administration could block tumor cell growth and metastasis in NSG mice. This therapeutic effect was observed with B16 cells but not ID8agg cells, illustrating tumor- or compartmental-specific effects in the therapeutic setting. Overall, our findings extend understanding of PD-L1 functions, illustrate nonimmune effects of anti-PD-L1 immunotherapy, and suggest broader uses for PD-L1 as a biomarker for assessing cancer therapeutic responses. Cancer Res; 76(23); 6964-74. ©2016 AACR.

Safety and Efficacy of Durvalumab (MEDI4736), an Anti-Programmed Cell Death Ligand-1 Immune Checkpoint Inhibitor, in Patients With Advanced Urothelial Bladder Cancer

PURPOSE

To investigate the safety and efficacy of durvalumab, a human monoclonal antibody that binds programmed cell death ligand-1 (PD-L1), and the role of PD-L1 expression on clinical response in patients with advanced urothelial bladder cancer (UBC).

METHODS

A phase 1/2 multicenter, open-label study is being conducted in patients with inoperable or metastatic solid tumors. We report here the results from the UBC expansion cohort. Durvalumab (MEDI4736, 10 mg/kg every 2 weeks) was administered intravenously for up to 12 months. The primary end point was safety, and objective response rate (ORR, confirmed) was a key secondary end point. An exploratory analysis of pretreatment tumor biopsies led to defining PD-L1-positive as ≥ 25% of tumor cells or tumor-infiltrating immune cells expressing membrane PD-L1.

RESULTS

A total of 61 patients (40 PD-L1-positive, 21 PD-L1-negative), 93.4% of whom received one or more prior therapies for advanced disease, were treated (median duration of follow-up, 4.3 months). The most common treatment-related adverse events (AEs) of any grade were fatigue (13.1%), diarrhea (9.8%), and decreased appetite (8.2%). Grade 3 treatment-related AEs occurred in three patients (4.9%); there were no treatment-related grade 4 or 5 AEs. One treatment-related AE (acute kidney injury) resulted in treatment discontinuation. The ORR was 31.0% (95% CI, 17.6 to 47.1) in 42 response-evaluable patients, 46.4% (95% CI, 27.5 to 66.1) in the PD-L1-positive subgroup, and 0% (95% CI, 0.0 to 23.2) in the PD-L1-negative subgroup. Responses are ongoing in 12 of 13 responding patients, with median duration of response not yet reached (range, 4.1+ to 49.3+ weeks).

CONCLUSION

Durvalumab demonstrated a manageable safety profile and evidence of meaningful clinical activity in PD-L1-positive patients with UBC, many of whom were heavily pretreated.

Follicle-Stimulating Hormone Receptor Is Expressed by Most Ovarian Cancer Subtypes and Is a Safe and Effective Immunotherapeutic Target

PURPOSE

To define the safety and effectiveness of T cells redirected against follicle-stimulating hormone receptor (FSHR)-expressing ovarian cancer cells.

EXPERIMENTAL DESIGN

FSHR expression was determined by Western blotting, immunohistochemistry, and qPCR in 77 human ovarian cancer specimens from 6 different histologic subtypes and 20 human healthy tissues. The effectiveness of human T cells targeted with full-length FSH in vivo was determined against a panel of patient-derived xenografts. Safety and effectiveness were confirmed in immunocompetent tumor-bearing mice, using constructs targeting murine FSHR and syngeneic T cells.

RESULTS

FSHR is expressed in gynecologic malignancies of different histologic types but not in nonovarian healthy tissues. Accordingly, T cells expressing full-length FSHR-redirected chimeric receptors mediate significant therapeutic effects (including tumor rejection) against a panel of patient-derived tumors in vivo In immunocompetent mice growing syngeneic, orthotopic, and aggressive ovarian tumors, fully murine FSHR-targeted T cells also increased survival without any measurable toxicity. Notably, chimeric receptors enhanced the ability of endogenous tumor-reactive T cells to abrogate malignant progression upon adoptive transfer into naïve recipients subsequently challenged with the same tumor. Interestingly, FSHR-targeted T cells persisted as memory lymphocytes without noticeable PD-1-dependent exhaustion during end-stage disease, in the absence of tumor cell immunoediting. However, exosomes in advanced tumor ascites diverted the effector activity of this and other chimeric receptor-transduced T cells away from targeted tumor cells.

CONCLUSIONS

T cells redirected against FSHR⁺ tumor cells with full-length FSH represent a promising therapeutic alternative against a broad range of ovarian malignancies, with negligible toxicity even in the presence of cognate targets in tumor-free ovaries. Clin Cancer Res; 23(2); 441-53. ©2016 AACR.

Rapamycin directly inhibits T cell lymphoma proliferation at high doses and facilitates immune-independent toxin-mediated killing at a low dose in vivo

Hyperactive mammalian target of rapamycin (mTOR) signaling that drives tumor growth makes mTOR inhibition an attractive cancer therapeutic strategy. mTOR inhibitors are approved to treat certain carcinomas, but effects on T cell hematologic malignancies, which also express hyper-activated mTOR, are less reported. We studied effects of the mTOR inhibitor rapamycin (Rapa) in mouse EL4 T cell lymphoma. Typical pharmacologic Rapa doses (1–8 mg/kg) significantly reduced tumor burden and improved survival in subcutaneous EL4 challenge independent of interferon (IFN)-γ or host T cells which we showed was by direct suppression of tumor cell proliferation. Though we found EL4 refractory to many anti-cancer immunotherapies, its growth was significantly slowed by regulatory T cell depletion with denileukin diftitox (DD) in vivo in a T cell-dependent fashion. However, typical Rapa doses inhibited T cell activation and tumor infiltration in vivo and failed to boost DD treatment effects as expected. Low dose (LD, 75 μg/kg) Rapa reportedly improves anti-tumor immunity and we found it increased potentially beneficial CD8+ T cells with a central memory phenotype (CD44hiCD62L+) in EL4 challenge, but without clinical effect. LD Rapa significantly enhanced DD treatment efficacy, but surprisingly, DD + LD Rapa treatment effects were independent of T cells, IFN-γ or perforin. Instead, Rapa up-regulated EL4 IL-2 receptor expression (DD binding site) in vitro and in vivo, apparently facilitating direct DD tumor cell killing. We thus show an unexpected mechanism for mTOR inhibitor in cancer immunotherapy and show distinct, biphasic mechanisms of action at typical pharmacologic doses versus LD Rapa that can be exploited clinically.

Microencapulated rapamycin prevents carcinogen and inflammation driven colon cancer through immune mechanisms

We tested microencapsulated rapamycin (eRapa, ~2.2 mg/kg rapamycin/mouse/day) in carcinogen (azoxymethane, AOM) + inflammatory agent (dextran sodium sulfate, DSS) colon cancer. WT BL6 mice fed eRapa before, and during AOM/DSS had significantly fewer colon tumors and tumor burden than control fed mice (empty microcapsules). eRapa prevented colon cancer in δ TCR KO mice lacking γδ T cells but not in IFN-γ KO mice. In carcinogen (DMBA) + inflammatory agent (TPA) skin cancer, IFN-γ and γδ T cells were both needed for eRapa cancer prevention, showing tumor-specific and common immune requirements for eRapa-mediated cancer prevention. In βδ TCR KO mice lacking all T cells, AOM/DSS induced no cancer or only few tumors, suggesting αβ T cells are required for colon neoplasia and cancer in the AOM/DSS model. Protection from acute colitis in this model usually predicts colon cancer protection. Strikingly, however, eRapa did not prevent acute clinical or histologic colitis induced by DSS, despite cancer protection, suggesting effects on chronic colitis, or induction of cancer-protective but not acute colitis-protective mechanisms. In acute colitis, eRapa significantly decreased spleen and colon weights and CD3+CD4+ T cells, and increased mesenteric lymph node γδ T cells (with decreased Vγ1.1+ and increased Vγ2+ subsets) consistent with altered inflammation and reduced CD4-CXCR3+ and CD4-α4β7 T cells (likely γδ T cells) consistent with altered trafficking but did not affect CCR9+ T cells. In chronic colitis, eRapa significantly increased γδ T cells (with no changes in Vγ1.1+ or Vγ2+ subsets) that could mediate cancer protection. These novel immune effects of rapamycin help define its cancer prevention mechanisms and define novel clinical uses.

Tumor B7-H1 regulates cancer stem cell generation and virulence

Cancer stem cells (CSC) resist chemotherapy and radiation, leading to treatment failures and reduced patient survival. Thus, CSC are clinically relevant therapy targets. B7-H1 is an immune checkpoint molecule and a target for αB7-H1 immunotherapy. We generated control (native B7-H1+) and B7-H1lo B16 melanoma lines by shRNA. B16*ctrl cultures were 4.2% CSCs (CD44+CD133+CD24+) vs. 0.19% in B16*B7-H1lo. CSC from B16*B7-H1lo cultures formed fewer and smaller (<50 μm) microspheres vs. many, large (100–150 μm) microspheres from control CSC. B16*ctrl CSC were more tumorigenic in mice than B7-H1lo CSC. B7-H1 expression was 2-fold higher on CSC vs. non-CSC. αB7-H1 reduced CSC numbers in B16*B7-H1lo cultures (~4-fold) but not control cultures. PD-1 expression was 2-fold higher in B16*B7-H1lo non-CSC vs B16*ctrl non-CSC. PD-1 was 5-fold higher in B7-H1lo CSC vs. B7-H1lo non-CSC, but equal in B16*ctrl CSC vs. non-CSC, suggesting PD-1 regulation by B7-H1. αPD-1 reduced CSC only in B7-H1*ctrl cultures (18.9% to 2.4%). 0.1 ng/ml IFN-γ for 48 hours reduced total cell counts in control vs. B7-H1lo cultures (by 55% and 65%, respectively). Strikingly, IFN-γ increased B7-H1lo CSC numbers 9.5-fold vs. 5.6-fold for control CSC. In parallel work, we tested ID8agg ovarian cancer cells. CSC (CD24+CD44+) were 12.2% vs. 2.2% in ID8*ctrl vs. ID8agg*B7-H1lo culture. B7-H1 and PD-1 expression was similar to B16. RNA-seq of total ID8agg cells showed significantly lower expression of CSC associated genes c-Kit, Lin28A and CD24 in B7-H1lo cells. Classic CSC genes were too low to read. B7-H1 is a candidate CSC regulator. It affects CSC PD-1 expression and alters αB7-H1, αPD-1 and IFN-γ effects differentially in CSC vs non-CSC suggesting novel pathogenic mechanisms.

Age effects on tumor B7-H1 and related immune therapies in an aggressive model of ovarian cancer

Age is the greatest cancer risk factor, but contributions of aging to tumor intrinsic properties and immunotherapy responses are poorly understood as most preclinical studies are in young hosts. We assessed age effects on tumor properties, progression, immunity and response to immunotherapies in an aggressive ID8 ovarian cancer line (ID8agg) that is poorly immunogenic and fatal in ~5 weeks. Young (3 mos) and aged (24 mos) BL6 females were injected intraperitoneally with 4×106 syngeneic ID8agg cells. In young mice, ID8agg ascites had more regulatory T cells (Tregs) and myeloid suppressor cells (MDSCs). Young mice gained 30% weight from ascites ~30 days after ID8agg challenge and formed 1–2 large, discrete peritoneal tumor masses. Aged mice tended to lose weight although ascites volumes were comparable to young, suggesting cachexia, and formed multiple small peritoneal nodules. Aged ascites had more tumor cells, Tregs, monocytic MDSCs and PD-1+ T cells versus young. Strikingly, tumor cells and MDSCs in aged ascites upregulated the immune checkpoint molecule B7-H1 greater than in young ascites. The combination of depleting Tregs and MDSCs with denileukin diftitox (DD), an FDA-approved IL-2/diphtheria toxin + αGr-1 temporarily slowed tumor progression in aged mice with increased IFNγ+ CD8 T cells, consistent with our prior B16 data. Treg depletion with either DD or αCD25 alone, or plus αCTLA4 did not significantly prevent ID8agg progression in young or aged mice. In young hosts, αB7-H1 slowed tumor growth and increased survival, with both clinical outcomes potentiated by adding αCTLA4. αCTLA4 + αB7-H1 effects in aged hosts are under study. Thus, we identified major age effects on tumor progression, and immune and immunotherapy responses.

Tumor-intrinsic B7-H1 in melanoma and ovarian cancer regulates mTOR, autophagy and tumor growth

Tumor B7-H1 (PD-L1) promotes tumor immune evasion by interaction with T cell PD-1. B16 melanoma and ID8agg ovarian cancer express B7-H1. We genetically made B7-H1lo or B7-H1hi lines to study additional B7-H1 effects. Control B16 and ID8agg grew more rapidly in vitro versus B7-H1lo cells and B7-H1hi B16 cells grew faster than control. In vivo, B16 and ID8agg grew faster than B7-H1lo lines in immunodeficient NSG mice. B16 challenge in NSG mice with B7-H1hi cells produced more lung metastases versus parental, which produced more metastases than B7-H1lo. αB7-H1 significantly reduced tumor growth and metastases. These data support an immune-independent role for tumor B7-H1 in tumor growth and metastatic spread. Control B16 and ID8agg cells had elevated TORC1 and reduced TORC2 versus B7-H1lo cells. The mTOR inhibitor rapamycin reduced cell growth greater in parental versus B7-H1lo cells in vitro. Also in line with reduced TORC1, B7-H1lo cells had increased autophagy (LC3-II/actin ratio and autophagosome formation) compared to parental cells. Notably, autophagy inhibitors chloroquine and 3-methyladenine had a greater inhibitory effect on in vitro proliferation of control B16 versus B7-H1lo cells. Inhibition of autophagy in vivo with either agent significantly reduced tumor growth of B16 but not B7-H1lo cells, suggesting that B7-H1 replete tumors are more dependent on the stress-modulating function of autophagy versus B7-H1lo tumors. Our studies show novel tumor-intrinsic B7-H1 signal effects that regulate mTOR and autophagy signals directly associated with immune-independent tumor growth, supporting a paradigm shifting concept that tumor B7-H1 augments stress response and metabolism through cell-intrinsic mechanisms.

Age and sex affect αCTLA-4 efficacy alone and combined with αB7-H1 or regulatory T cell depletion in a melanoma model

Background

Most cancer patients are aged but most preclinical studies are in young hosts. We tested age effects on immunotherapy to further our understanding and identify strategies.

Methods

Young (3 mos) and aged (~26 mos) BL6 mice were injected subcutaneously with syngeneic B16 melanoma cells. 7 days later, mice got 2 μg denileukin diftitox (DD), an FDA-approved IL-2/diphtheria toxin or 200 μg αCD25 (both to deplete Tregs) ± 50 μg αCTLA-4 or 100 μg αB7-H1. 5 days later mice got a 2nd treatment.

Results

αCTLA-4 depleted intra-tumor Tregs in young but not aged males, a major age effect. In young BL6 males or females αCTLA-4 + αB7-H1 rejected B16 tumors better than either single agent. In aged males, αCTLA4 + αB7-H1 treated B16, but surprisingly accelerated tumors in aged females. Individual agents were effective in young hosts but had negligible effects in the aged. αCTLA-4 + either DD or αCD25 to deplete Tregs significantly reduced tumor growth in young mice but DD was better than αCD25. Neither combo treated B16 in aged mice. This DD dose did not deplete Tregs in aged mice as well as young, but higher DD doses were equally effective. In support, in Foxp3DTR mice, in which we deplete ~100% Treg (versus 20–50% with DD or αCD25), aged mice potently rejected B16.

Conclusions

Cancer immunotherapy studies in young give an incomplete understanding of clinical effects and mechanisms in the aged most at risk for cancer. We identify major Treg effects and differential Treg depletion efficacy of αCTLA4 and DD contributing to treatment failures in the aged and means to mitigate effects. With appropriate treatments, even very old mice can mount effective anti-tumor immunity. Novel sex differences in aged are unlikely estrogen-related and require further study.

Effect of vorinostat (VOR) and hydroxychloroquine (HCQ) on immunity and autophagy in metastatic colorectal cancer (mCRC)

670

Background:HCQ enhances the anti-cancer activity of the histone deacetylase inhibitor, VOR in pre-clinical CRC models. Our phase 1 dose escalation trial found that patients (pts) with mCRC obtained prolonged clinical benefit from VOR + HCQ. Thus, a single arm expansion cohort in refractory mCRC was done. Methods: Pts with refractory mCRC received VOR 600 mg by mouth (PO) + HCQ 400 mg PO daily, in a 3-week cycle. The primary endpoint was median progression-free survival (mPFS). Secondary endpoints: median overall survival (mOS), adverse events (AE) (NCI-CTCAEv3.0), flow cytometry (FACS) of peripheral blood mononuclear cells (PBMCs), tumor biopsies. Results: 20 pts were enrolled (19 evaluable for survival): mean age 61 (44-74). Female 7/male 23, 9 Caucasian/10 Hispanic/1 Black, 11 KRAS mutated. ECOG 0-1 (18 pts). 3+ prior lines (13), previous regorafenib (4). Dose level reduction on study (7). mPFS 2.8 months (95% CI: 1.63-8.16). mOS 6.7 months (95% CI: 4.63-NR). Treatment-related grade 3 AEs: nausea/vomiting (3), anemia (3). Grade 4 thrombocytopenia (3). Grade 4 INR elevation (1 pt on Coumadin). No grade 5 AEs. Five pts (26%) had stable disease ≥12 weeks. Treatment significantly reduced regulatory and PD-1+ (exhausted) CD4+ and CD8+ T cells and increased CD45RO+CD62L-CD4+ (effector) T cells, consistent with improved anti-tumor immunity. On-study biopsies (3) showed increased lysosomal protease CTSD and LC3-II consistent with autophagy inhibition. Conclusions: VOR/HCQ is active, safe and tolerated in refractory CRC patients, resulting in potentially improved anti-tumor immunity (decreased exhausted and regulatory T cells and increased effector phenotype T cells) and reduced tumor autophagy. A randomized phase II trial of VOR/HCQ versus regorafenib is now open. Clinical trial information: NCT01023737.

Chronic mTOR inhibition in mice with rapamycin alters T, B, myeloid, and innate lymphoid cells and gut flora and prolongs life of immune-deficient mice

The mammalian (mechanistic) target of rapamycin (mTOR) regulates critical immune processes that remain incompletely defined. Interest in mTOR inhibitor drugs is heightened by recent demonstrations that the mTOR inhibitor rapamycin extends lifespan and healthspan in mice. Rapamycin or related analogues (rapalogues) also mitigate age-related debilities including increasing antigen-specific immunity, improving vaccine responses in elderly humans, and treating cancers and autoimmunity, suggesting important new clinical applications. Nonetheless, immune toxicity concerns for long-term mTOR inhibition, particularly immunosuppression, persist. Although mTOR is pivotal to fundamental, important immune pathways, little is reported on immune effects of mTOR inhibition in lifespan or healthspan extension, or with chronic mTOR inhibitor use. We comprehensively analyzed immune effects of rapamycin as used in lifespan extension studies. Gene expression profiling found many and novel changes in genes affecting differentiation, function, homeostasis, exhaustion, cell death, and inflammation in distinct T- and B-lymphocyte and myeloid cell subpopulations. Immune functions relevant to aging and inflammation, and to cancer and infections, and innate lymphoid cell effects were validated in vitro and in vivo. Rapamycin markedly prolonged lifespan and healthspan in cancer- and infection-prone mice supporting disease mitigation as a mechanism for mTOR suppression-mediated longevity extension. It modestly altered gut metagenomes, and some metagenomic effects were linked to immune outcomes. Our data show novel mTOR inhibitor immune effects meriting further studies in relation to longevity and healthspan extension.

Immunotherapy for ovarian cancer

OPINION STATEMENT

All work referenced herein relates to treatment of epithelial ovarian carcinomas, as their treatment differs from ovarian germ cell cancers and other rare ovarian cancers, the treatments of which are addressed elsewhere. Fallopian tube cancers and primary peritoneal adenocarcinomatosis are also generally treated as epithelial ovarian cancers. The standard of care initial treatment of advanced stage epithelial ovarian cancer is optimal debulking surgery as feasible plus chemotherapy with a platinum plus a taxane agent. If this front-line approach fails, as it too often the case, several FDA-approved agents are available for salvage therapy. However, because no second-line therapy for advanced-stage epithelial ovarian cancer is typically curative, we prefer referral to clinical trials as logistically feasible, even if it means referring patients outside our system. Immune therapy has a sound theoretical basis for treating carcinomas generally, and for treating ovarian cancer in particular. Advances in understanding the immunopathogenic basis of ovarian cancer, and the immunopathologic basis for prior failures of immunotherapy for it and other carcinomas promises to afford novel treatment approaches with potential for significant efficacy, and reduced toxicities compared with cytotoxic agents. Thus, referral to early phase immunotherapy trials for ovarian cancer patients that fail conventional treatment merits consideration.

Interventions to Slow Aging in Humans: Are We Ready?

The workshop entitled ‘Interventions to Slow Aging in Humans: Are We Ready?’ was held in Erice, Italy, on October 8–13, 2013, to bring together leading experts in the biology and genetics of aging and obtain a consensus related to the discovery and development of safe interventions to slow aging and increase healthy lifespan in humans. There was consensus that there is sufficient evidence that aging interventions will delay and prevent disease onset for many chronic conditions of adult and old age. Essential pathways have been identified, and behavioral, dietary, and pharmacologic approaches have emerged. Although many gene targets and drugs were discussed and there was not complete consensus about all interventions, the participants selected a subset of the most promising strategies that could be tested in humans for their effects on healthspan. These were: (i) dietary interventions mimicking chronic dietary restriction (periodic fasting mimicking diets, protein restriction, etc.); (ii) drugs that inhibit the growth hormone/IGF-I axis; (iii) drugs that inhibit the mTOR–S6K pathway; or (iv) drugs that activate AMPK or specific sirtuins. These choices were based in part on consistent evidence for the pro-longevity effects and ability of these interventions to prevent or delay multiple age-related diseases and improve healthspan in simple model organisms and rodents and their potential to be safe and effective in extending human healthspan. The authors of this manuscript were speakers and discussants invited to the workshop. The following summary highlights the major points addressed and the conclusions of the meeting.

Prevention of carcinogen and inflammation-induced dermal cancer by oral rapamycin includes reducing genetic damage

Cancer prevention is a cost-effective alternative to treatment. In mice, the mTOR inhibitor rapamycin prevents distinct spontaneous, noninflammatory cancers, making it a candidate broad-spectrum cancer prevention agent. We now show that oral microencapsulated rapamycin (eRapa) prevents skin cancer in dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) carcinogen-induced, inflammation-driven carcinogenesis. eRapa given before DMBA/TPA exposure significantly increased tumor latency, reduced papilloma prevalence and numbers, and completely inhibited malignant degeneration into squamous cell carcinoma. Rapamycin is primarily an mTORC1-specific inhibitor, but eRapa did not reduce mTORC1 signaling in skin or papillomas, and did not reduce important proinflammatory factors in this model, including p-Stat3, IL17A, IL23, IL12, IL1β, IL6, or TNFα. In support of lack of mTORC1 inhibition, eRapa did not reduce numbers or proliferation of CD45(-)CD34(+)CD49f(mid) skin cancer initiating stem cells in vivo and marginally reduced epidermal hyperplasia. Interestingly, eRapa reduced DMBA/TPA-induced skin DNA damage and the hras codon 61 mutation that specifically drives carcinogenesis in this model, suggesting reduction of DNA damage as a cancer prevention mechanism. In support, cancer prevention and DNA damage reduction effects were lost when eRapa was given after DMBA-induced DNA damage in vivo. eRapa afforded picomolar concentrations of rapamycin in skin of DMBA/TPA-exposed mice, concentrations that also reduced DMBA-induced DNA damage in mouse and human fibroblasts in vitro. Thus, we have identified DNA damage reduction as a novel mechanism by which rapamycin can prevent cancer, which could lay the foundation for its use as a cancer prevention agent in selected human populations.

Host miR155 promotes tumor growth through a myeloid-derived suppressor cell-dependent mechanism

miR155 is a regulator of immune cell development and function that is generally thought to be immunostimulatory. However, we report here that genetic ablation of miR155 renders mice resistant to chemical carcinogenesis and the growth of several transplanted tumors, suggesting that miR155 functions in immunosuppression and tumor promotion. Host miR155 deficiency promoted overall antitumor immunity despite the finding of defective responses of miR155-deficient dendritic cells and antitumor T cells. Further analysis of immune cell compartments revealed that miR155 regulated the accumulation of functional myeloid-derived suppressive cells (MDSC) in the tumor microenvironment. Specifically, miR155 mediated MDSC suppressor activity through at least two mechanisms, including SOCS1 repression and a reduced ability to license the generation of CD4(+)Foxp3(+) regulatory T cells. Importantly, we demonstrated that miR155 expression was required for MDSC to facilitate tumor growth. Thus, our results revealed a contextual function for miR155 in antitumor immunity, with a role in MDSC support that appears to dominate in tumor-bearing hosts. Overall, the balance of these cellular effects appears to be a root determinant of whether miR155 promotes or inhibits tumor growth.

Sequential intravesical mitomycin plus Bacillus Calmette-Guérin for non-muscle-invasive urothelial bladder carcinoma: translational and phase I clinical trial

PURPOSE

To determine the safety and toxicities of sequential MMC (mitomycin C) + BCG (bacillus Calmette-Guérin) in patients with non-muscle-invasive bladder cancer (NMIBC) and explore evidence for potentiation of BCG activity by MMC.

EXPERIMENTAL DESIGN

A 3 + 3 phase I dose-escalation trial of six weekly treatments was conducted in patients with NMIBC. MMC (10, 20, or 40 mg) was instilled intravesically for 30 minutes, followed by a 10-minute washout with gentle saline irrigation and then instillation of BCG (half or full strength) for 2 hours. Urine cytokines were monitored and compared with levels in a control cohort receiving BCG only. Murine experiments were carried out as described previously.

RESULTS

Twelve patients completed therapy, including 3 patients receiving full doses. The regimen was well tolerated with no treatment-related dose-limiting toxicities. Urinary frequency and urgency, and fatigue were common. Eleven (91.7%) patients were free of disease at a mean (range) follow-up of 21.4 (8.4-27.0) months. Median posttreatment urine concentrations of IL2, IL8, IL10, and TNFα increased over the 6-week treatment period. A greater increase in posttreatment urinary IL8 during the 6-week period was observed in patients receiving MMC + BCG compared with patients receiving BCG monotherapy. In mice, intravesical MMC + BCG skewed tumor-associated macrophages (TAM) toward a beneficial M1 phenotype.

CONCLUSIONS

Instillation of sequential MMC + BCG is safe tolerable up to 40-mg MMC plus full-strength BCG. This approach could provide improved antitumor activity over BCG monotherapy by augmenting beneficial M1 TAMs.

A phosphotyrosine switch determines the antitumor activity of ERβ

Estrogen receptors ERα and ERβ share considerable sequence homology yet exert opposite effects on breast cancer cell proliferation. While the proliferative role of ERα in breast tumors is well characterized, it is not clear whether the antitumor activity of ERβ can be mobilized in breast cancer cells. Here, we have shown that phosphorylation of a tyrosine residue (Y36) present in ERβ, but not in ERα, dictates ERβ-specific activation of transcription and is required for ERβ-dependent inhibition of cancer cell growth in culture and in murine xenografts. Additionally, the c-ABL tyrosine kinase and EYA2 phosphatase directly and diametrically controlled the phosphorylation status of Y36 and subsequent ERβ function. A nonphosphorylatable, transcriptionally active ERβ mutant retained antitumor activity but circumvented control by upstream regulators. Phosphorylation of Y36 was required for ERβ-mediated coactivator recruitment to ERβ target promoters. In human breast cancer samples, elevated phosphorylation of Y36 in ERβ correlated with high levels of c-ABL but low EYA2 levels. Furthermore, compared with total ERβ, the presence of phosphorylated Y36-specific ERβ was strongly associated with both disease-free and overall survival in patients with stage II and III disease. Together, these data identify a signaling circuitry that regulates ERβ-specific antitumor activity and has potential as both a prognostic tool and a molecular target for cancer therapy.

Optimization of immunotherapy in elderly cancer patients

Increasing evidence has revealed the incidence of cancer augments with aging, which could be attributed to a multitude of age-associated changes including the dysregulation of the immune system. Although many reports demonstrate the efficacy of cancer immunotherapies in numerous preclinical studies, most experiments have been performed in young animals. Studies from our group and others show that cancer immunotherapy could be ineffective in old mice, even though the same therapeutic treatment works efficiently in young mice. Given that cancer occurs mostly in the elderly, we should take age-associated immune dysregulation into consideration to achieve the effectiveness of immunotherapeutic interventions in the old. Understanding both age-related and tumor-related immune alterations might be equally important in improving the effectiveness of immunotherapy. This article reviews a number of age-associated immune alterations with specific attention given to the impact on antitumor responses, and also discusses possible strategies for optimization of immunotherapeutic interventions in the elderly.

Combined autophagy and HDAC inhibition: a phase I safety, tolerability, pharmacokinetic, and pharmacodynamic analysis of hydroxychloroquine in combination with the HDAC inhibitor vorinostat in patients with advanced solid tumors

We previously reported that inhibition of autophagy significantly augmented the anticancer activity of the histone deacetylase (HDAC) inhibitor vorinostat (VOR) through a cathepsin D-mediated mechanism. We thus conducted a first-in-human study to investigate the safety, preliminary efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and VOR in patients with advanced solid tumors. Of 27 patients treated in the study, 24 were considered fully evaluable for study assessments and toxicity. Patients were treated orally with escalating doses of HCQ daily (QD) (d 2 to 21 of a 21-d cycle) in combination with 400 mg VOR QD (d one to 21). Treatment-related adverse events (AE) included grade 1 to 2 nausea, diarrhea, fatigue, weight loss, anemia, and elevated creatinine. Grade 3 fatigue and/or myelosuppression were observed in a minority of patients. Fatigue and gastrointestinal AE were dose-limiting toxicities. Six-hundred milligrams HCQ and 400 mg VOR was established as the maximum tolerated dose and recommended phase II regimen. One patient with renal cell carcinoma had a confirmed durable partial response and 2 patients with colorectal cancer had prolonged stable disease. The addition of HCQ did not significantly impact the PK profile of VOR. Treatment-related increases in the expression of CDKN1A and CTSD were more pronounced in tumor biopsies than peripheral blood mononuclear cells. Based on the safety and preliminary efficacy of this combination, additional clinical studies are currently being planned to further investigate autophagy inhibition as a new approach to increase the efficacy of HDAC inhibitors.

Female gender is associated with a worse survival after radical cystectomy for urothelial carcinoma of the bladder: a competing risk analysis

OBJECTIVE

To determine the association of gender with outcome after radical cystectomy for patients with bladder cancer.

METHODS

An observational cohort study was conducted using retrospectively collected data from 11 centers on patients with advanced bladder cancer treated with radical cystectomy. The association of gender with disease recurrence and cancer-specific mortality was examined using a competing risk analysis.

RESULTS

The study comprised 4296 patients, including 890 women (21%). The median follow-up duration was 31.5 months for all patients. Disease recurred in 1430 patients (33.9%) (36.8% of women and 33.1% of men) at a median of 11 months after surgery. Death from any cause was observed in 46.0% of men and 50.1% of women. Cancer-specific death was observed in 33.0% of women and 27.2% of men. Multivariable regression with competing risk found that female gender was associated with an increased risk for disease recurrence and cancer-specific mortality (hazard ratio, 1.27; 95% confidence interval, 1.108-1.465; P = .007) compared with male gender. Important limitations include the inability to account for additional potential confounders, such as differences in environmental exposures, treatment selection, and histologic subtypes between men and women.

CONCLUSION

Our analysis identified female gender as a poor-risk feature for patients undergoing radical cystectomy. This adverse prognostic factor was independent of standard clinical and pathologic features and competing risk from non-cancer-related death.