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BRCA1-mediated homologous recombination is an important DNA repair mechanism that is the target of FDA-approved PARP inhibitors, yet details of BRCA1-mediated functions remain to be fully elucidated. Similarly, immune checkpoint molecules are targets of FDA-approved cancer immunotherapies, but the biological and mechanistic consequences of their application are incompletely understood. We show here that the immune checkpoint molecule PD-L1 regulates homologous recombination in cancer cells by promoting BRCA1 nuclear foci formation and DNA end resection. Genetic depletion of tumor PD-L1 reduced homologous recombination, increased nonhomologous end joining, and elicited synthetic lethality to PARP inhibitors olaparib and talazoparib in vitro in some, but not all, BRCA1 wild-type tumor cells. In vivo, genetic depletion of tumor PD-L1 rendered olaparib-resistant tumors sensitive to olaparib. In contrast, anti-PD-L1 immune checkpoint blockade neither enhanced olaparib synthetic lethality nor improved its efficacy in vitro or in wild-type mice. Tumor PD-L1 did not alter expression of BRCA1 or its cofactor BARD1 but instead coimmunoprecipitated with BARD1 and increased BRCA1 nuclear accumulation. Tumor PD-L1 depletion enhanced tumor CCL5 expression and TANK-binding kinase 1 activation in vitro, similar to known immune-potentiating effects of PARP inhibitors. Collectively, these data define immune-dependent and immune-independent effects of PARP inhibitor treatment and genetic tumor PD-L1 depletion. Moreover, they implicate a tumor cell–intrinsic, immune checkpoint–independent function of PD-L1 in cancer cell BRCA1-mediated DNA damage repair with translational potential, including as a treatment response biomarker. Significance: PD-L1 upregulates BRCA1-mediated homologous recombination, and PD-L1–deficient tumors exhibit BRCAness by manifesting synthetic lethality in response to PARP inhibitors, revealing an exploitable therapeutic vulnerability and a candidate treatment response biomarker. See related commentary by Hanks, p. 2069

Recent studies suggest that B cells could play an important role in the tumor microenvironment. However, the role of humoral responses in endometrial cancer remains insufficiently investigated. Using a cohort of 107 patients with different histological subtypes of endometrial carcinoma, we evaluated the role of coordinated humoral and cellular adaptive immune responses in endometrial cancer. Concomitant accumulation of T, B, and plasma cells at tumor beds predicted better survival. However, only B-cell markers corresponded with prolonged survival specifically in high-grade endometrioid type and serous tumors. Immune protection was associated with class-switched IgA and, to a lesser extent, IgG. Expressions of polymeric immunoglobulin receptor (pIgR) by tumor cells and its occupancy by IgA were superior predictors of outcome and correlated with defects in methyl-directed DNA mismatch repair. Mechanistically, pIgR-dependent, antigen-independent IgA occupancy drove activation of inflammatory pathways associated with IFN and TNF signaling in tumor cells, along with apoptotic and endoplasmic reticulum stress pathways, while thwarting DNA repair mechanisms. Together, these findings suggest that coordinated humoral and cellular immune responses, characterized by IgA:pIgR interactions in tumor cells, determine the progression of human endometrial cancer as well as the potential for effective immunotherapies. Significance: This study provides new insights into the crucial role of humoral immunity in human endometrial cancer, providing a rationale for designing novel immunotherapies against this prevalent malignancy. See related commentary by Osorio and Zamarin, p. 766

Legends for all 7 supplementary figures

Figure S6 - Figure.S6 shows combination of rapamycin and BCG increase percentage of effector memory γδ T cells and production of cytokine such as IFNγ within γδ T cells.

Reagent information for flow cytometry and ELISPOT assay.

Bacillus Calmette-Guérin (BCG) is the most effective intravesical agent at reducing recurrence for patients with high-grade, non–muscle-invasive bladder cancer. Nevertheless, response to BCG is variable and strategies to boost BCG efficacy have not materialized. Prior work demonstrated a requirement for either conventional αβ or nonconventional γδ T cells in mediating BCG treatment efficacy, yet the importance of T-cell antigen specificity for BCG's treatment effect is unclear. Here, we provide direct evidence to show that BCG increases the number of tumor antigen–specific αβ T cells in patients with bladder cancer and protects mice from subsequent same-tumor challenge, supporting BCG induction of tumor-specific memory and protection. Adoptive T-cell transfers of antigen-specific αβ T cells into immunodeficient mice challenged with syngeneic MB49 bladder tumors showed that both tumor and BCG antigen–specific αβ T cells contributed to BCG efficacy. BCG-specific antitumor immunity, however, also required nonconventional γδ T cells. Prior work shows that the mTOR inhibitor rapamycin induces the proliferation and effector function of γδ T cells. Here, rapamycin increased BCG efficacy against both mouse and human bladder cancer in vivo in a γδ T cell–dependent manner. Thus, γδ T cells augment antitumor adaptive immune effects of BCG and support rapamycin as a promising approach to boost BCG efficacy in the treatment of non–muscle-invasive bladder cancer.

Supplementary Figure Legends

Supplementary Figures S1-6

Supplemental Figures S1-4. Supplementary Figure S1: eRapa prevents DMBA/TPA-induced dermal neoplasia and malignant degeneration in WT mice. Supplementary Figure S2: eRapa does not suppress mTORC1 signaling in whole skin. Supplementary Figure S3: eRapa is not a calorie restriction mimetic. Supplementary Figure S4: eRapa prevents DMBA/TPA-induced dermal neoplasia in T cell deficient mice.

Expression of ESR1 by PCR and lack of responsiveness of tumor cells used in vivo.

Mutation of a single copy of the adenomatous polyposis coli (APC) gene results in familial adenomatous polyposis (FAP), which confers an extremely high risk for colon cancer. ApcMin/+ mice exhibit multiple intestinal neoplasia (MIN) that causes anemia and death from bleeding by 6 months. Mechanistic target of rapamycin complex 1 (mTORC1) inhibitors were shown to improve ApcMin/+ mouse survival when administered by oral gavage or added directly to the chow, but these mice still died from neoplasia well short of a natural life span. The National Institute of Aging Intervention Testing Program showed that enterically targeted rapamycin (eRapa) extended life span for wild-type genetically heterogeneous mice in part by inhibiting age-associated cancer. We hypothesized that eRapa would be effective in preventing neoplasia and extend survival of ApcMin/+ mice. We show that eRapa improved survival of ApcMin/+ mice in a dose-dependent manner. Remarkably, and in contrast to previous reports, most of the ApcMin/+ mice fed 42 parts per million eRapa lived beyond the median life span reported for wild-type syngeneic mice. Furthermore, chronic eRapa did not cause detrimental immune effects in mouse models of cancer, infection, or autoimmunity, thus assuaging concerns that chronic rapamycin treatment suppresses immunity. Our studies suggest that a novel formulation (enteric targeting) of a well-known and widely used drug (rapamycin) can dramatically improve its efficacy in targeted settings. eRapa or other mTORC1 inhibitors could serve as effective cancer preventatives for people with FAP without suppressing the immune system, thus reducing the dependency on surgery as standard therapy. Cancer Prev Res; 7(1); 169–78. ©2013 AACR.

MOV file - 3205K, Three ApcMIn/+ 42 ppm eRapa-fed female mice at 902 days of age.

Complication data for all patients

The mechanistic target of rapamycin (mTOR) integrates environmental inputs to regulate cellular growth and metabolism in tumors. However, mTOR also regulates T-cell differentiation and activation, rendering applications of mTOR inhibitors toward treating cancer complex. Preclinical data support distinct biphasic effects of rapamycin, with higher doses directly suppressing tumor cell growth and lower doses enhancing T-cell immunity. To address the translational relevance of these findings, the effects of the mTOR complex 1 (mTORC1) inhibitor, rapamycin, on tumor and T cells were monitored in patients undergoing cystectomy for bladder cancer. MB49 syngeneic murine bladder cancer models were tested to gain mechanistic insights. Surgery-induced T-cell exhaustion in humans and mice and was associated with increased pulmonary metastasis and decreased PD-L1 antibody efficacy in mouse bladder cancer. At 3 mg orally daily, rapamycin concentrations were 2-fold higher in bladder tissues than in blood. Rapamycin significantly inhibited tumor mTORC1, shown by decreased rpS6 phosphorylation in treated versus control patients (P = 0.008). Rapamycin reduced surgery-induced T-cell exhaustion in patients, evidenced by a significant decrease in the prevalence of dysfunctional programmed death-1 (PD-1)–expressing T cells. Grade 3 to 4 adverse event rates were similar between groups, but rapamycin-treated patients had a higher rate of wound complications versus controls. In conclusion, surgery promoted bladder cancer metastasis and decreased the efficacy of postoperative bladder cancer immunotherapy. Low-dose (3 mg daily) oral rapamycin has favorable pharmacodynamic and immune modulating activity in surgical patients and has the potential to decrease surgery-induced immune dysfunction.

AVI file - 9806K, A 42 ppm-fed ApcMin/+ female at 1087 days of age.

Fig. S2 Representative flow cytometry data in humans and mice samples. A. Flow cytometry gating strategy for defining Tregs phenotypically by expression of CD3, CD4, CD25 and Foxp3.

Flow cytometry gating strategies.

Suppl. Fig. 1 confirms that ID8agg is more virulent versus parental ID8 in WT mice. Suppl. Fig. 2 provides relevant details for plasmids used to make recombinant cell lines, and gives Western blot validations for each PD-L1lo clone described. Suppl, Fig. 3 shows that αPD-L1 reduces tumor growth and metastatic spread of B16hi cells in NSG mice and shows color photomicrographs of lungs from treated mice. Suppl. Fig. 4 shows that αPD-L1 immunotherapy fails to treat ID8agg in wild-type mice. Suppl. Fig. 5 shows that tumor PD-L1 is necessary and sufficient for αPD-L1 treatment effects on B16 cells challenged into wild type mice. Suppl. Fig. 6 provides much additional Western blot data on mTORC1 and mTORC2 signals in B16 and ID8agg cells after rapamycin or chloroquine treatments. Suppl. Fig. 7 shows effects of tumor cell PD-L1 expression on B16 and ID8agg cell proliferation sensitivity to TNFα, cis-platinum and paclitaxel in vitro.

Recent studies suggest that B cells could play an important role in the tumor microenvironment. However, the role of humoral responses in endometrial cancer remains insufficiently investigated. Using a cohort of 107 patients with different histological subtypes of endometrial carcinoma, we evaluated the role of coordinated humoral and cellular adaptive immune responses in endometrial cancer. Concomitant accumulation of T, B, and plasma cells at tumor beds predicted better survival. However, only B-cell markers corresponded with prolonged survival specifically in high-grade endometrioid type and serous tumors. Immune protection was associated with class-switched IgA and, to a lesser extent, IgG. Expressions of polymeric immunoglobulin receptor (pIgR) by tumor cells and its occupancy by IgA were superior predictors of outcome and correlated with defects in methyl-directed DNA mismatch repair. Mechanistically, pIgR-dependent, antigen-independent IgA occupancy drove activation of inflammatory pathways associated with IFN and TNF signaling in tumor cells, along with apoptotic and endoplasmic reticulum stress pathways, while thwarting DNA repair mechanisms. Together, these findings suggest that coordinated humoral and cellular immune responses, characterized by IgA:pIgR interactions in tumor cells, determine the progression of human endometrial cancer as well as the potential for effective immunotherapies.Significance:This study provides new insights into the crucial role of humoral immunity in human endometrial cancer, providing a rationale for designing novel immunotherapies against this prevalent malignancy.See related commentary by Osorio and Zamarin, p. 766

Table S2

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.

Purpose:Immunotherapy treats some cancers, but not ovarian cancer. Regulatory T cells (Tregs) impede anti-ovarian cancer immunity but effective human Treg-directed treatments are lacking. We tested Treg depletion with denileukin diftitox (DD) ± IFNα as ovarian cancer immunotherapy.Patients and Methods:Mice with syngeneic ID8 ovarian cancer challenge were treated with DD, IFNα, or both. The phase 0/I trial tested one dose-escalated DD infusion for functional Treg reduction, safety, and tolerability. The phase II trial added IFNα2a to DD if DD alone failed clinically.Results:DD depleted Tregs, and improved antitumor immunity and survival in mice. IFNα significantly improved antitumor immunity and survival with DD. IFNα did not alter Treg numbers or function but boosted tumor-specific immunity and reduced tumor Treg function with DD by inducing dendritic cell IL6. DD alone was well tolerated, depleted functional blood Tregs and improved immunity in patients with various malignancies in phase 0/I. A patient with ovarian cancer in phase 0/I experienced partial clinical response prompting a phase II ovarian cancer trial, but DD alone failed phase II. Another phase II trial added pegylated IFNα2a to failed DD, producing immunologic and clinical benefit in two of two patients before a DD shortage halt. DD alone was well tolerated. Adding IFNα increased toxicities but was tolerable, and reduced human Treg numbers in blood, and function through dendritic cell–induced IL6 in vitro.Conclusions:Treg depletion is clinically useful but unlikely alone to cure ovarian cancer. Rational treatment agent combinations can salvage clinical failure of Treg depletion alone, even when neither single agent provides meaningful clinical benefit.

Tregs expand in tumor draining lymph nodes

Supplementary Figure from IgA-Dominated Humoral Immune Responses Govern Patients' Outcome in Endometrial Cancer

Supplementary Materials and Methods

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. Clin Cancer Res; 21(2); 303–11. ©2014 AACR.

Table S1

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-L1lo cells), which express basal PD-L1. We observed that PD-L1lo cells proliferated more weakly than control cells in vitro. As expected, PD-L1lo 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-L1lo 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.

Supplemental Methods

Supplemental Figure 1. (A) Cytotoxicity of FSHCER or mock transduced T-cells of OVCAR-3 luciferase tumor cells measured by luciferase detection after co-culture of 18 hours. (B) Gating strategy followed for the flow cytometry based cytotoxicity assay. After gating on the singlet cells we could gate the tumor cells and exclude T-cells by FSC and SSC (confirmed by the no Tcell control) and measure the percentage of living cells as double negatives from Annexin-V and 7AAD. Supplemental Figure 2. (A) immunohistochemistry showing a section CAOV3 tumor stained with FSHR18 antibody followed by secondary anti-mouse (FSHR18) or secondary alone (Negative). 20x, scale bar: 1 um. (B) Western blot and qPCR showing FSHR expression of different ovarian cancer and breast cancer tumor cell lines. (C) Tumor volume of three ovarian patient-derived xenograft tumors grown in the flank of NOD-SCID mice (n=2 mice per tumor, one case-one control, single experiment) injected intratumorally with 10 million FSHCER or mock transduced T-cells (arrows mark time of T-cell injection). Common axis used for easier cross comparison. Supplemental Figure 3. (A) FSHR mRNA of FACS-sorted ID8-Defb29/Vegf-a/Fshr from the peritoneal cavity of orthotopic ID8-Defb29/Vegf-a/Fshr-bearing mice treated with either FSHCER, mock transduced T-cells or PBS. (B) Normalized real-time quantitative-PCR of FSHR expression in the human healthy ovarian tissue shown in Figure 3A, a human serous ovarian carcinoma specimen and 2 additional cell lines. (C) Absence of expression of the FSHR in untransduced ID8-Defb29/Vegf-a cells, compared to FSHR-transduced clones (40 PCR cycles).

S1 shows DMBA/TPA modulation of epidermal alphabeta and gammadelta TCRhi T cells in WT and CXCR3-/- mice. S2 shows epidermal chemokines in WT and IFN-gamma-/- mice treated with Eudragit control or eRapa. S3 shows mTOR signaling in epidermal and draining lymph node T cells. S4 shows human gammadelta TCR expression in gammadelta T cells.

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.

Acquired resistance to BRAFV600E inhibitors (BRAFi) in melanoma remains a common clinical obstacle, as is the case for any targeted drug therapy that can be developed given the plastic nature of cancers. Although there has been significant focus on the cancer cell-intrinsic properties of BRAFi resistance, the impact of BRAFi resistance on host immunity has not been explored. Here we provide preclinical evidence that resistance to BRAFi in an autochthonous mouse model of melanoma is associated with restoration of myeloid-derived suppressor cells (MDSC) in the tumor microenvironment, initially reduced by BRAFi treatment. In contrast to restoration of MDSCs, levels of T regulatory cells remained reduced in BRAFi-resistant tumors. Accordingly, tumor gene expression signatures specific for myeloid cell chemotaxis and homeostasis reappeared in BRAFi-resistant tumors. Notably, MDSC restoration relied upon MAPK pathway reactivation and downstream production of the myeloid attractant CCL2 in BRAFi-resistant melanoma cells. Strikingly, although combination checkpoint blockade (anti-CTLA-4 + anti-PD-1) was ineffective against BRAFi-resistant melanomas, the addition of MDSC depletion/blockade (anti-Gr-1 + CCR2 antagonist) prevented outgrowth of BRAFi-resistant tumors. Our results illustrate how extrinsic pathways of immunosuppression elaborated by melanoma cells dominate the tumor microenvironment and highlight the need to target extrinsic as well as intrinsic mechanisms of drug resistance. Cancer Res; 77(7); 1599–610. ©2017 AACR.

Supplementary figure 1. Rapamycin reduces EL4 bone marrow infiltration. Supplementary figure 2. HD rapamycin impairs T cell activation and infiltration. Supplementary figure 3. Effects of rapamycin on mTOR signals and Ki67 (proliferation) in EL4 cells studied ex vivo. Supplementary figure 4. Dose response effects of rapamycin on EL4 in vivo. Supplementary figure 5. EL4 is refractory to many standard immunotherapies. Supplementary figure 6. LD rapamycin plus DD-mediated EL4 cell death is not blocked by anti-CD25 in vivo. Supplementary figure 7. LD rapamycin improves DD treatment efficacy of B16F10. Supplementary figure 8. Rapamycin + DD killing of EL4 and B16 cells is blocked with anti-CD25 + anti-CD22 in vitro. Supplementary figure 9. CD25 and CD122 expression are not upregulated by rapamycin treatment in vitro in mouse tumor lines B16F10 or ID8agg. Supplementary figure 10. CD25 and CD122 expression are not upregulated by rapamycin treatment in vivo in mouse challenged with B16F10. Supplementary figure 11. CD25 and CD122 expression on human NM001 and Jurkat cell lines is unchanged with temsirolimus in vitro.

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.

Description of additional methods and procedures used in the study. Also includes Supplementary References.

Supplemental Table. Number (percent) of patients experiencing symptoms by week of therapy

Supplementary figures 1-10. Figure S1. IL-2c increases conventional CD4 T cell in ascites three weeks after final IL-2c, but does not affect ascites Treg and effector T cell numbers at one week after final IL-2c administration. Figure S2. IL-2c treatment increases CD8+ central and effector memory T cells in the ascites, and central memory T cells in TDLN. Fig S3. Additional Treg phenotype in ascites and TDLN after IL-2c treatment. Fig S4. IL-2c directly inhibits Treg suppression specifically in the tumor microenvironment. Fig S5. IL-2 signaling is not impaired in TDLN after IL-2c treatment. Figure S6. Specific Treg depletion is highly effective against ID8agg. Figure S7. αCD25 attenuates IL-2c-induced tumor rejection and T cell function in ID8agg OC. Figure S8. IL-2c promotes intratumoral T cell infiltration. Figure S9. IL-2c reduces intratumoral Treg activation and functional molecules in B16 melanoma. Figure S10. IL-2c increases TIGIT+LAG-3+PD-1+ CD8+ T cells in B16 tumors.

Regulatory T cells (Treg) are critical mediators of immunosuppression in established tumors, although little is known about their role in restraining immunosurveillance during tumorigenesis. Here, we employ an inducible autochthonous model of melanoma to investigate the earliest Treg and CD8 effector T-cell responses during oncogene-driven tumorigenesis. Induction of oncogenic BRAFV600E and loss of Pten in melanocytes led to localized accumulation of FoxP3+ Tregs, but not CD8 T cells, within 1 week of detectable increases in melanocyte differentiation antigen expression. Melanoma tumorigenesis elicited early expansion of shared tumor/self-antigen–specific, thymically derived Tregs in draining lymph nodes, and induced their subsequent recruitment to sites of tumorigenesis in the skin. Lymph node egress of tumor-activated Tregs was required for their C-C chemokine receptor 4 (Ccr4)–dependent homing to nascent tumor sites. Notably, BRAFV600E signaling controlled expression of Ccr4-cognate chemokines and governed recruitment of Tregs to tumor-induced skin sites. BRAFV600E expression alone in melanocytes resulted in nevus formation and associated Treg recruitment, indicating that BRAFV600E signaling is sufficient to recruit Tregs. Treg depletion liberated immunosurveillance, evidenced by CD8 T-cell responses against the tumor/self-antigen gp100, which was concurrent with the formation of microscopic neoplasia. These studies establish a novel role for BRAFV600E as a tumor cell–intrinsic mediator of immune evasion and underscore the critical early role of Treg-mediated suppression during autochthonous tumorigenesis.Significance: This work provides new insights into the mechanisms by which oncogenic pathways impact immune regulation in the nascent tumor microenvironment. Cancer Res; 78(17); 5038–49. ©2018 AACR.

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Supplementary Methods from CD73 on Tumor Cells Impairs Antitumor T-Cell Responses: A Novel Mechanism of Tumor-Induced Immune Suppression

Supplementary Figure 3 from Cytokine Receptor CXCR4 Mediates Estrogen-Independent Tumorigenesis, Metastasis, and Resistance to Endocrine Therapy in Human Breast Cancer

Supplementary Methods, Figure Legends 1-5 from Cytokine Receptor CXCR4 Mediates Estrogen-Independent Tumorigenesis, Metastasis, and Resistance to Endocrine Therapy in Human Breast Cancer