Efficacy and Safety of Avelumab for Patients With Recurrent or Refractory Ovarian Cancer: Phase 1b Results From the JAVELIN Solid Tumor Trial

Importance

Current treatment options for progressive ovarian cancer provide limited benefit, particularly in patients whose disease has become resistant to platinum-based chemotherapy.

Objective

To assess the efficacy and safety of avelumab, an anti-programmed death-ligand 1 agent, in a cohort of patients with previously treated recurrent or refractory ovarian cancer.

Design, Setting, and Participants

In an expansion cohort of a phase 1b, open-label study (JAVELIN Solid Tumor), 125 patients with advanced ovarian cancer who had received chemotherapy including a platinum agent were enrolled between November 6, 2013, and August 27, 2015. Statistical analysis was performed from December 31, 2016, to October 9, 2018.

Intervention

Patients received avelumab, 10 mg/kg, every 2 weeks until disease progression, unacceptable toxic effects, or withdrawal from the study.

Main Outcomes and Measures

Prespecified end points in this cohort included confirmed best overall response (per Response Evaluation Criteria In Solid Tumors, version 1.1), immune-related best overall response, duration of response, progression-free survival, overall survival, results of programmed death-ligand 1 expression-based analyses, and safety.

Results

A total of 125 women (median age, 62.0 years [range, 27-84 years]) who had received a median of 3 prior lines of treatment (range, 0-10) for advanced disease were enrolled in the study. Patients received avelumab for a median of 2.8 months (range, 0.5-27.4 months), with a median follow-up of 26.6 months (range, 16-38 months). A confirmed objective response occurred in 12 patients (9.6%; 95% CI, 5.1%-16.2%), including a complete response in 1 patient (0.8%) and a partial response in 11 patients (8.8%). The 1-year progression-free survival rate was 10.2% (95% CI, 5.4%-16.7%) and median overall survival was 11.2 months (95% CI, 8.7-15.4 months). Infusion-related reactions occurred in 25 patients (20.0%). Other frequent treatment-related adverse events (any grade event occurring in ≥10% of patients) were fatigue (17 [13.6%]), diarrhea (15 [12.0%]), and nausea (14 [11.2%]). Grade 3 or higher treatment-related adverse events occurred in 9 patients (7.2%), of which only the level of lipase increased (3 [2.4%]) occurred in more than 1 patient. Twenty-one patients (16.8%) had an immune-related adverse event of any grade. No treatment-related deaths occurred.

Conclusions and Relevance

Avelumab demonstrated antitumor activity and acceptable safety in heavily pretreated patients with recurrent or refractory ovarian cancer.

Trial Registration

ClinicalTrials.gov identifier: NCT01772004.

Immuno-Oncology in the Era of Personalized Medicine

Personalized medicine in oncology utilizes evidence derived from genetic, immune, and proteomic profiling to inform therapeutic options as well as provide prognostic information for each unique individual and their tumor. Our ability to biologically and immunologically define each patient's tumor has been driven by the development of assays characterizing the genomic and proteomic profiles of tumors that in turn have led to the development of large biologic databases and computational tools for the analysis of these large data sets. In Immuno-oncology, the introduction of checkpoint inhibitors and their approval across multiple tumor types has led to the recognition that the majority of patients will not clinically respond to these therapies but will remain at risk for the development of significant immunologic side effects. This challenge highlights the need for the development and validation of both predictive biomarkers for response to such therapies as well as biomarkers prognostic of disease course. Despite extensive investigation into predictive biomarkers using these biologic databases and computational methods, only recently has progress been made in this area. This progress is the first step allowing us to identify patients likely to benefit from these therapies and moving our field closer to a truly personalized approach to the use of immune therapies in oncology.

SITC 2018 workshop report: Immuno-Oncology Biomarkers: State of the Art

Identification of biomarkers in cancer immunotherapy that predict therapeutic response and/or limit adverse events are a critical need in the field. To address recent progress and hurdles around cancer biomarker development and utilization, the Society for Immunotherapy of Cancer (SITC) convened a workshop, “Immuno-Oncology Biomarkers: State of the Art,” on May 16–17, 2018. Topics discussed included challenges in handling biospecimens, identification and validation of new biomarkers, data sharing, and collaborating across disciplines to advance biomarker development. Panel discussions followed session presentations to help foster participant conversation and discuss future projects and collaborations. The results of the Workshop include the development of new initiatives for the SITC Biomarkers Committee.

Abstract 1266: Downregulation of PD-L1 by NSAID administration augments the effects of a multi-antigen vaccine for the prevention of adenomatous polyps in APC(Min/+) mice

Introduction: We have shown that treatment of APC(Min/+) mice with NSAIDs will inhibit development of adenomatous polyps and induce significant levels of polyp-infiltrating CD8 T-cells. We sought to identify the mechanism of NSAID induced immune stimulation and questioned whether administration of NSAIDs concurrent with vaccination could further reduce polyp formation.

Methods: PD-L1 expression and T-cell infiltrates were assessed by IHC and flow cytometry. MC38 and RKO (murine/human colorectal carcinoma cell lines) were treated with naproxen (200uM-1000 uM) and harvested at 24, 48 and 72h. At 4-6 weeks, APC(Min/+) mice were given a multi-antigen peptide vaccine (COX2, CDC25B, EGFR) with CFA/IFA or adjuvant alone. Two groups received 400ppm naproxen orally 7d/wk for 18 weeks. Polyps were quantified at ≤24 weeks. Spleens and polyps were collected for IFN-gamma ELISPOT, flow cytometry, and IHC.

Results: Polyps from the APC(Min/+) mouse and both cancer cell lines highly express PD-L1. PD-L1 expression was significantly decreased in MC38 (p<0.01) and RKO (p<0.01) as compared to control after incubation with naproxen at all doses. The inhibitory effect of NSAIDs on PD-L1 expression was both time and dose dependent. We evaluated the in vivo effect of combination immunoprevention in the APC(Min/+). Animals receiving vaccine alone showed a 33% inhibition of polyp formation while naproxen alone showed 54% inhibition (p<0.0001) compared to adjuvant alone. Combination treatment demonstrated significantly greater inhibition of polyps than either modality (p<0.001), 81% inhibition vs. adjuvant. Antigen specific T-cells could be detected at higher levels than control antigen in both the vaccine alone (p=0.0001) and combination-treated animals (p<0.0001). The antigen specific responses seen in combination treated animals were nearly two-fold that of vaccine alone (p=0.008). No antigen specific immunity was detected in naproxen and adjuvant only treated mice. The magnitude of the immune response was significantly correlated with lower polyp counts, with a Pearson correlation coefficient of -0.55 (p=0.0014). Detailed immunologic analysis of tumors will be presented.

Conclusions: NSAIDs, via modulation of PD-L1, synergize with vaccines to increase immunogenicity and enhance influx of polyp infiltrating lymphocytes. This synergy results in superior prevention of polyp formation compared to treatment with NSAID or vaccine alone and has high potential for clinical application.

Citation Format: Mary L. Disis, Lauren R. Corulli, Clinton Grubbs, Ronald A. Lubet, Paul Cowan, Ekram Gad. Downregulation of PD-L1 by NSAID administration augments the effects of a multi-antigen vaccine for the prevention of adenomatous polyps in APC(Min/+) mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1266.

Abstract 2224: Panel of autoantibodies to seven early tumor-associated overexpressed proteins can identify women with DCIS from women with benign breast tumors detected by mammography

While mammography is essential to identify early breast cancer, the sensitivity is dependent on breast characteristics. Currently all breast masses identified by mammography have to be biopsied to determine if malignant. A serum-based biomarker used along with mammography to identify pre-malignant lesions to biopsy would both improve the sensitivity of mammography and reduce the number of biopsies needed. We have identified a panel of autoantibodies found in early breast cancer. An autoantibody biomarker is ideal because antibody immunity can be detected with very low levels of antigen with direct antigen recognition by B cells resulting in clonal amplification of antigen specific plasma cells. Work in our laboratory has identified tumor-associated proteins present in pre-malignant tumors that are necessary for survival of human breast cancer cells across breast cancer subtypes. We have found that increased autoantibodies to seven of these early tumor-associated proteins (PDIA6, KRT8, SERBP1, ARPC2, RRM2, AURKA, and NDC80) were present in the sera of women with pre-malignant breast atypia but not women with no breast atypia or benign breast atypia and may be a panel to increase sensitivity of mammography.

The presence of autoantibodies was evaluated in 191 individuals, 36 women with no breast atypia, 12 women with benign breast atypia, 36 patients with fibroadenoma, 12 patients with hyperplasia, 59 patients with ductal carcinoma in situ (DCIS), and 36 patients with invasive breast cancer (IBC). We found more women with pre-malignant breast atypia had increased autoantibodies to at least one of the seven early tumor associated proteins as compared to women with either no breast atypia or benign breast atypia. For example, a positive autoantibody response is over 2 standard deviations above the mean found in women with no breast atypia. There were 2.9% of women with positive autoantibody response to RRM2 in women without breast atypia. However, in women with breast atypia, there was a positive antibody response in 41.7% of individuals with hyperplasia, 48.6% of individuals with fibroadenoma, 34.5% of individuals with DCIS, and 28.6% of individuals with IBC. All seven autoantibodies could predict patients with hyperplasia, fibroadenoma, DCIS, and IBC from both women with no atypia and women with benign breast atypia. For example, the seven-antibody panel could identify DCIS from women with no breast atypia with AUC of 0.95 (95% CI 0.912 to 0.995) and from women with benign breast atypia with AUC of 0.71 (95% CI 0.519 to 0.898). This is a better AUC than seen with previous published autoantibody profiles in DCIS. Future studies will validate these findings with the goal of developing a serum biomarker that will improve sensitivity of mammography.

Citation Format: Sasha Elizabeth Stanton, Erik Ramos, Mary L. Disis. Panel of autoantibodies to seven early tumor-associated overexpressed proteins can identify women with DCIS from women with benign breast tumors detected by mammography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2224.

Immunologic synergy between intermittent NSAID administration and antigen specific vaccination in inhibiting the development of intestinal polyps in the APC(Min/+)

Introduction

Studies from our group have shown that administration of NSAIDs in mouse models of Familial Adenomatous Polyposis results in a decrease in polyp formation and a significant increase in CD8 tumor infiltrating lymphocytes with downregulation of PD-L1 expression in tumors. We questioned whether a short course of NSAID could be used in combination with vaccination to even further reduce the development of intestinal polyps.

Methods

At 4–6 weeks of age, APC(Min/+) male/female mice were given CFA/IFA adjuvant with or without a multi-antigen (EGFR, COX2, CDC25B) peptide vaccine. Upon start of vaccinations, normal food or 400ppm naproxen mixed with food was provided either continuously (CON; 18w on) or intermittently (INT; 3w on + 3w off for 3 cycles). Animals were euthanized at 22±1 weeks and tumors quantified. Systemic and tissue specific immunity was measured by ELISPOT, FACS, and direct tumor staining.

Results

Tumor development was significantly inhibited both by vaccine alone and naproxen alone (p<0.0001). Combining naproxen (INT or CON) with vaccine was additive compared to vaccine alone (p<0.0001) and naproxen alone (INT+Vaccine p<0.0007; CON+Vaccine p<0.0003). INT naproxen was as effective as CON, with or without vaccine (p>0.999). Mice with greater tumor inhibition demonstrated higher magnitude antigen specific T-cell responses (p=0.0441, r=−0.423) and CD8+ T-cell infiltration (p<0.0001, r=−0.506) than those with less protection.

Conclusions

Data demonstrates that short-term administration of NSAIDs may be as effective as the more toxic long-duration alternative. Further, a short course of NSAID significantly synergizes with antigen specific vaccination to inhibit the development of polyps.

Vaccine targeting antigens associated with cancer stem cells/epithelial to mesenchymal transition inhibits triple negative breast cancer growth

Triple negative breast cancer (TNBC) is characterized by higher relapse and poor survival rates compared to other breast cancer types and is marked by a cancer stem cell (CSC)/epithelial to mesenchymal transition (EMT) signature. We questioned whether a vaccine targeting CSC/EMT associated proteins could prevent development of TNBC. We identified five overexpressed proteins found in TNBC and associated with different CSC/EMT pathways. We used a scoring system derived from three common algorithms for predicting class II MHC binding to select Th epitopes for CD105, CDH3, MDM2, SOX-2 and YB-1. Those epitopes that induced a selective Th1 (IFN-gamma) immune response in human population based screening were included in a multi-antigen vaccine. Epitopes were highly homologous between mouse and man. Immunization with the multi-antigen vaccine induced Th1 specific for all five antigens compared to adjuvant control (p<0.05 for all). Immunity persisted 3 months after the final vaccine (p<0.05 for all). Vaccination generated an antigen-specific cytotoxic T-cell (CTL) immune response to three antigens (p<0.05). The vaccine increased effector memory T-cells by 2-fold compared to control (p=0.03). Tumor growth in vaccinated FVB-Tg(C3-1-TAg) mice, a basal breast cancer model, was inhibited by over 80% compared to control mice (p<0.0001). We observed significantly more CTL (p=0.04) and Th1 (p<0.001) infiltrating the tumor with a concomitant reduction in cells expressing the stem cell marker Sca-1 (p=0.003) after immunization with vaccine compared to control. This multi-antigen vaccine targeting CSC/EMT antigens is currently being investigated in a Phase I clinical trial (NCT02157051).

The Immune Landscape of Cancer

We performed an extensive immunogenomic analysis of more than 10,000 tumors comprising 33 diverse cancer types by utilizing data compiled by TCGA. Across cancer types, we identified six immune subtypes-wound healing, IFN-γ dominant, inflammatory, lymphocyte depleted, immunologically quiet, and TGF-β dominant-characterized by differences in macrophage or lymphocyte signatures, Th1:Th2 cell ratio, extent of intratumoral heterogeneity, aneuploidy, extent of neoantigen load, overall cell proliferation, expression of immunomodulatory genes, and prognosis. Specific driver mutations correlated with lower (CTNNB1, NRAS, or IDH1) or higher (BRAF, TP53, or CASP8) leukocyte levels across all cancers. Multiple control modalities of the intracellular and extracellular networks (transcription, microRNAs, copy number, and epigenetic processes) were involved in tumor-immune cell interactions, both across and within immune subtypes. Our immunogenomics pipeline to characterize these heterogeneous tumors and the resulting data are intended to serve as a resource for future targeted studies to further advance the field.

Immunotherapy in breast cancer: An introduction

The field of breast cancer immunology has progressed tremendously over the last decade. Twenty years ago immunotherapy was not considered for the treatment of breast cancers because breast cancer was not considered immunogenic. Today we know that most patients with breast cancer have some evidence of an adaptive immune response against their tumors, detectable either in the peripheral blood or in the tumor. Moreover, immunity to breast cancer begins at the earliest stages of the disease, in some patients prior to diagnosis. Recent evidence suggests that lymphocytes infiltrating breast cancers and found in the tumor stroma are strong prognostic indicators of a beneficial disease outcome. These observations now pave the way for the integration of immunomodulation into standard of care therapy for the treatment of breast cancer.

TLR8 ligation induces apoptosis of monocytic myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) accumulate in tumors and the peripheral blood of cancer patients and demonstrate cancer-promoting activity across multiple tumor types. A limited number of agents are known to impact MDSC activity. TLR8 is expressed in myeloid cells. We investigated expression of TLR8 on MDSC and the effect of a TLR8 agonist, motolimod, on MDSC survival and function. TLR8 was highly expressed in monocytic MDSC (mMDSC) but absent in granulocytic MDSC (gMDSC). Treatment of human PBMC with motolimod reduced the levels of mMDSC in volunteers and cancer donors versus control (P < 0.001). Motolimod did not impact levels of gMDSC. The reduction of mMDSC was due to induced cell death by TLR8 ligation. Pretreatment of PBMC with a FAS neutralizing antibody inhibited motolimod-induced reduction of mMDSC (P < 0.001). Finally, we demonstrated that mMDSC impeded IL-2 secretion by CD3/CD28-activated T cells; IL-2 secretion was partially restored when cells were cocultured with motolimod (142 ± 36 pg/ml vs. 59 ± 13 pg/ml; P = 0.03). There is increasing evidence that MDSCs contribute to the progression of cancer by inhibiting tumor-directed T cells. TLR8 agonists may synergize with cancer immunotherapeutic approaches to enhance the antitumor effects of the adaptive immune response.

A First-in-Human Phase I Study of Subcutaneous Outpatient Recombinant Human IL15 (rhIL15) in Adults with Advanced Solid Tumors

Purpose: Preclinical data established IL15 as a homeostatic factor and powerful stimulator of NK and CD8⁺ T-cell function, the basis for clinical testing.Experimental Design: A first-in-human outpatient phase I dose escalation trial of subcutaneous (SC) rhIL15 was conducted in refractory solid tumor cancer patients. Therapy consisted of daily (Monday-Friday) subcutaneous injections of rhIL15 for two consecutive weeks (10 total doses/cycle). Clinical response was assessed by RECIST. Pharmacokinetics of rhIL15 and immune biomarkers were evaluated.Results: Nineteen patients were treated with rhIL15 at dose levels of 0.25, 0.5, 1, 2, and 3 mcg/kg/day. Fourteen patients completed ≥ 2 cycles of therapy that was well tolerated. One serious adverse event (SAE), grade 2 pancreatitis, required overnight hospitalization. Enrollment was halted after a patient receiving 3 mcg/kg/day developed a dose-limiting SAE of grade 3 cardiac chest pain associated with hypotension and increased troponin. No objective responses were observed; however, several patients had disease stabilization including a renal cell carcinoma patient who continued protocol treatment for 2 years. The treatment induced profound expansion of circulating NK cells, especially among the CD56^bright subset. A proportional but less dramatic increase was found among circulating CD8⁺ T cells with maximal 3-fold expansion for the 2 and 3 mcg/kg patients.Conclusions: SC rhIL15 treatment was well tolerated, producing substantial increases in circulating NK and CD8⁺ T cells. This protocol establishes a safe outpatient SC rhIL15 regimen of 2 mcg/kg/day dosing amenable to self-injection and with potential as a combination immunotherapeutic agent. Clin Cancer Res; 24(7); 1525-35. ©2017 AACR.

Topical Imiquimod Plus Nab-paclitaxel for Breast Cancer Cutaneous Metastases: A Phase 2 Clinical Trial

Importance

Salvage chemotherapy for recurrent chest wall lesions in breast cancer results in response rates of 20% to 30%. Preclinical studies showed significant disease regression could be induced in murine chest wall mammary cancers with a topical toll-like receptor (TLR)-7 agonist, imiquimod.

Objective

To evaluate the safety and objective response rate (ORR) of imiquimod in combination with systemic albumin bound paclitaxel in treatment-refractory breast cancer of the chest wall.

Design, Setting, and Particpants

A single arm phase 2 clinical trial of 15 patients with breast cancer previously treated in an academic medical center setting between 2009 and 2012 for chest wall disease that had recurred.

Interventions

Imiquimod cream, 5%, was applied topically to a designated target lesion once per day for 4 consecutive days on days 1 through 4, 8 through 11, 15 through 18, and 22 through 25 of a 28-day cycle, for 12 weeks. Albumin bound paclitaxel, 100 mg/m2, was given intravenously on days 1, 8, and 15, and repeated every 28 days over the 12-week period.

Main Outcomes and Measures

The primary endpoint was safety and ORR. Secondary endpoints included the generation of tumor-infiltrating lymphocytes and modulation of immune cell populations.

Results

The median age at baseline of the 15 study participants was 54 years (range, 46-92 years). Fourteen patients were evaluable. Combination therapy was associated with low-grade toxic effects. Of 358 adverse events 330 (92%) were grades 1 and 2. Five (36%) patients achieved a compete response and another 5 (36%) were partial responders for an overall response rate of 72% (10 of 14). The response duration was limited. Pretreatment levels of programmed death-1 (PD-1)+ peripheral blood T cells (PD-1+ cluster of differentiation [CD]4+; 95% CI, 2.68-6.63; P < .001 and PD-1+CD8+; 95% CI, 1.13-8.35; P = .01) and monocytic myeloid derived suppressor cells (mMDSC) (95% CI, 3.62-12.74; P = .001) greater than controls predicted suboptimal clinical response.

Conclusions and Relevance

Chemoimmunomodulation with a TLR-7 agonist and albumin bound paclitaxel is effective in inducing disease regression in treatment-refractory breast cancer chest wall metastases but responses are short-lived. Preexisting levels of cells indicating either T-cell exhaustion or systemic immunosuppression may be markers of selection for responsive patients.

Trial Registration

clinicaltrials.gov Identifier: NCT00821964.

Surrogate in vitro activation of innate immunity synergizes with interleukin-7 to unleash rapid antigen-driven outgrowth of CD4+ and CD8+ human peripheral blood T-cells naturally recognizing MUC1, HER2/neu and other tumor-associated antigens

Effective adoptive immunotherapy has proved elusive for many types of human cancer, often due to difficulties achieving robust expansion of natural tumor-specific T-cells from peripheral blood. We hypothesized that antigen-driven T-cell expansion might best be triggered in vitro by acute activation of innate immunity to mimic a life-threatening infection. Unfractionated peripheral blood mononuclear cells (PBMC) were subjected to a two-step culture, first synchronizing their exposure to exogenous antigens with aggressive surrogate activation of innate immunity, followed by γ-chain cytokine-modulated T-cell hyperexpansion. Step 1 exposure to GM-CSF plus paired Toll-like receptor agonists (resiquimod and LPS), stimulated abundant IL-12 and IL-23 secretion, as well as upregulated co-stimulatory molecules and CD11c expression within the myeloid (CD33+) subpopulation. Added synthetic long peptides (>20aa) derived from widely expressed oncoproteins (MUC1, HER2/neu and CMVpp65), were reliably presented to CD4+ T-cells and cross-presented to CD8+ T-cells. Both presentation and cross-presentation demonstrated proteasomal and Sec61 dependence that could bypass the endoplasmic reticulum. Step 2 exposure to exogenous IL-7 or IL-7+IL-2 produced selective and sustained expansion of both CD4+ and CD8+ peptide-specific T-cells with a predominant interferon-γ-producing T1-type, as well as the antigen-specific ability to lyse tumor targets. Other γ-chain cytokines and/or combinations were initially proliferogenic, but followed by a contractile phase not observed with IL-7 or IL-7+IL-2. Regulatory T-cells were minimally propagated under these culture conditions. This mechanistically rational culture sequence, effective even for unvaccinated donors, enables rapid preparation of T-cells recognizing tumor-associated antigens expressed by the majority of human cancers, including pancreatic cancers, breast cancers and glioblastomas.

Abstract 623: Identifying candidate antigens for a ductal carcinoma in situ vaccine that are essential to breast cancer survival across multiple subtypes

Vaccine therapy may be ideal to destroy ductal carcinoma in situ (DCIS) and prevent recurrence. A vaccine can induce type 1 T-cells against DCIS antigens that could migrate from the circulation to invade and destroy the tumor as well as generate immunologic memory to provide long lasting protective immunity. One of the limitations to developing a DCIS vaccine is identifying antigens that target all subtypes of DCIS. DCIS has many of the same molecular abnormalities as invasive breast cancer (IBC), including overexpressed proteins that may be drivers of progression to invasive disease. Eliminating cells that are overexpressing driver proteins by vaccination may prevent progression to IBC if such proteins could be determined.

In this study, we identified proteins that were overexpressed from normal breast in both DCIS and IBC across fifteen Geo and Array Express data sets. From 68 candidate proteins, we identified twelve whose expression was necessary for cancer cell survival across breast cancer subtypes. We selected overexpressed proteins necessary for cancer survival using a high throughput siRNA screen and chose candidates that increased apoptosis and decreased cell survival in HER2 positive (HER2), triple negative (TN), and hormone receptor positive HER2 negative (HR) human breast cancer cell lines with decreased expression of the target protein. For example, decreased expression of NDC80 caused decreased cell survival to 56±3% in HR, 46±3% in TN, and 77±2% in HER2 breast cancer cell lines and increased apoptosis by 1.4±0.03 fold in HR and 1.2±0.03 fold in TN breast cancer cell lines. Decreased expression of RRM2 caused decreased cell survival to 66±3% in HR and 89±2% in HER2 breast cancer cell lines and increased apoptosis by 1.6±0.08 fold in HR, 1.4±0.07 fold in TN, and 2.4±0.3 fold in HER2 breast cancer cell lines. Twelve proteins (AURKA, KIF11, NDC80, RRM2, SDC1, UBE2C, HJURP, CENPA, CENPF, HIST2H2AA3, HIST1H2BD, and TOP2A) were essential for cancer cell survival in at least 2 breast cancer subtypes.

These protein targets are immunogenic in patients with DCIS. In the sera of women without breast atypia (n=36), autoantibodies to NDC80 were detected with a mean of 5.3±1.8 ng/mL while in women with fibroadenoma (n=36) autoantibodies were detected with a mean of 8.3±1.5 (p=0.05). In the sera of women without breast atypia (n=36), autoantibodies to RRM2 were detected with a mean of 0.16±0.7 ng/mL while in women with fibroadenoma (n=36) autoantibodies were detected with a mean of 7.2±2.1 (p=0.05) and in women with DCIS (n=59) autoantibodies were detected with a mean of 2.6±0.6 ng/mL (p=0.0003). These proteins represent DCIS antigens of biologic importance in tumor growth and, potentially, progression to IBC and are candidate immunogens for a vaccine to treat DCIS.

Citation Format: Sasha Elizabeth Stanton, Erik Ramos, James Annis, Andrew Timms, Tessa Rue, Mary L. Disis. Identifying candidate antigens for a ductal carcinoma in situ vaccine that are essential to breast cancer survival across multiple subtypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 623. doi:10.1158/1538-7445.AM2017-623

Abstract 3687: Bexarotene activates type 1 antigen presenting cells, increases tumor infiltrating CD8 T-cells, and augments the anti-tumor activity of chemotherapy in breast cancer

Bexarotene is an oral rexinoic receptor (RXR) agonist that has anti-proliferative activity in breast cancer. RXRs are nuclear receptors that heterodimerize, including with the retinoic acid receptor (RAR), to activate transcription for processes including cellular differentiation, embryonic development, proliferation, and metabolism. We have demonstrated that bexarotene can enhance cancer vaccine efficacy by synergizing with a multi-antigen vaccine to prevent breast cancer in the TgMMTV-neu model. Bexarotene as a single agent increased CD8 T-cell tumor infiltration. We therefore questioned the mechanism by which bexarotene acted as an immunomodulatory drug.

Evaluating RXR expression in human peripheral blood monocytes (PBMC) (n=10), we found that RXR is not expressed in NK T-cells or B-cells and in only a minority of CD4+ (5.1 ± 4%) and CD8+ T-cells (3.6 ± 3%). RXR, however, is expressed in 24.9±13% of macrophages, 38.6 ± 14% of plasmacytic dendritic cells (pDC), and 33.1 ± 16% of monocytic dendritic cells (mDC). PMBC treated with increasing doses of bexarotene for 48 hours had increased co-stimulatory CD40 expression on mDC (p=0.0011 between 0 and 20 uM bexarotene) and increased type 1 cytokine release including IL-1β (p=0.03 between 0 and 20 uM bexarotene) and TNFα (p=0.02 between 0 and 20 uM bexarotene) but not type 2 cytokine release of IL-10 (p=0.21) and IL-4 (p=0.5). These data demonstrate that bexarotene can activate type 1 dendritic cells

Since activated type 1 dendritic cells are effective at presenting tumor antigens from dying tumor cells, we wanted to determine if bexarotene could increase type 1 immunity in the tumor and thereby enhance the efficacy of paclitaxel chemotherapy. In TgMMTV-neu mice with 100 mm3 established spontaneous tumors (n=5), 50 mg/kg bexarotene inhibited tumor growth by 49% and increased the influx of intratumoral CD8+ T-cells by 61% as compared to PBS treated mice (p=0.01). 10 mg/kg paclitaxel inhibited tumor growth by 57% and increased intratumoral CD8+ T-cells by 45% as compared to PBS treated mice (p=0.003). Paclitaxel and bexarotene together inhibited tumor growth by 83% (p=0.02 compared to bexarotene or paclitaxel alone) and increased intratumoral CD8+ T-cell infiltrate by 58% as compared to PBS treated mice (p=0.01). Bexarotene could both activate type 1 APC and increase the CD8 T-cell infiltrate in the tumor and enhance the efficacy of paclitaxel. These data suggest concurrent adminstration of immunomodulatory bexarotene with paclitaxel may result in augmentation of the anti-tumor activity of chemotherapy in breast cancer.

Citation Format: Sasha Elizabeth Stanton, Ekram Gad, Lauren R. Corulli-Rastetter, Mary L. Disis. Bexarotene activates type 1 antigen presenting cells, increases tumor infiltrating CD8 T-cells, and augments the anti-tumor activity of chemotherapy in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3687. doi:10.1158/1538-7445.AM2017-3687

Abstract KP03: NOVEL IMMUNOTHERAPEUTICS FOR OVARIAN CANCER

In the last decade we have seen significance advances in the understanding of how the immune system modulates the ovarian tumor microenvironment and cancer growth. A number of studies have shown that high levels of tumor infiltrating adaptive immune system cells (B-cells and T-cells) found in ovarian cancer are associated with a favorable prognosis, especially if there is evidence of reduced regulatory T-cells. Robust T-cell tumor infiltration (TIL) is associated with PD-L1 upregulation. Almost half of ovarian cancers demonstrate enhanced PD-L1 expression on tumor cells and/or tumor infiltrating immune system cells. Immune checkpoint inhibitor monoclonal antibodies block receptors such as PD-1 and PD-L1 which suppress T-cell function. The largest study of immune checkpoint inhibition in ovarian cancer evaluated the blockade of PD-L1 using avelumab. In this phase I/II study 124 patients with recurrent disease, considered chemotherapy refractory, were treated with 10mg/kg avelumab every 2 weeks (65% of patients with 3 or greater salvage regimens). The overall response rate was 10% with a stable disease rate of 44% resulting in a disease control rate of 54%. Overall survival at 12 months was 44%. Clinical response did not correlate with either PDL-1 expression on tumor or immune infiltrating cells or BRCA mutation status. A randomized trial of avelumab in combination with pegylated liposomal doxorubicin in cisplatin refractory ovarian cancer has been initiated. Pre-clinical studies have shown that clinical responses to immune checkpoint inhibitor therapy in ovarian cancer may be enhanced by increasing Type I T-cell infiltration concurrent with therapy. Clinical strategies aimed at increasing TIL include the use of vaccines immunizing against ovarian cancer antigens to stimulate T-cells trafficking to tumor. Specific chemotherapy may result in increased TIL as some cytotoxic agents have been shown to modulate both the level and phenotype of TIL in ovarian cancer. An alternate approach is to suppress alternate pathways of tumor immune escape such as depletion of macrophage or inhibition of the IDO pathway to enhance immune activation. Several promising combination immunotherapy strategies are currently being evaluated in ovarian cancer.

Citation Format: Mary L. Disis, MD. NOVEL IMMUNOTHERAPEUTICS FOR OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr KP03.

Abstract NTOC-097: VACCINATION TARGETING INSULIN–LIKE GROWTH FACTOR BINDING PROTEIN–2 (IGFBP–2) IN ADVANCED OVARIAN CANCER: SAFETY, IMMUNOGENICITY, AND SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS (SEER) COMPARISON

BACKGROUND: Immunization against self-antigens can induce regulatory responses that inhibit desirable Type 1 antitumor immune responses. Deletion of epitopes that favor a regulatory phenotype may improve the efficacy of therapeutic vaccines. We have developed a novel IGFBP-2 targeting DNA plasmid vaccine that selectively induces Type 1 immunity. IGFBP-2 regulates invasiveness and metastases in ovarian cancer. Eradication of ovarian cancer cells expressing IGFBP-2 through effective immunization could prevent disease relapse or metastasis.

METHODS: Twenty-five patients with advanced stage or recurrent ovarian cancer treated to complete remission after primary or salvage therapy received 3 monthly doses of an IGFBP-2 DNA vaccine in a single-arm, non-randomized study. ELISPOT and flow cytometry were used to characterize antigen specific T-cell responses. Serum antibodies were measured using ELISA and Western blot. The SEER database was reviewed to identify women diagnosed between 2006 and 2012 matched for age, year of diagnosis and stage of diagnosis. The difference between dates of diagnosis and enrollment (lead time) was calculated for each patient receiving vaccine. Only SEER patients who survived at least as long as the lead time of their matches plus an additional 6 months were kept for analysis. In cases where this resulted in no SEER matched patients, unmatched vaccine patients were excluded. Overall survival (OS) was analyzed using Cox models and the Kaplan-Meier method.

RESULTS: 206 adverse events (AE) were recorded. Fatigue (12%) and injection site reactions (12%) were the most common. 97% of AE were grades 1-2, 3% grade 3, and no grades 4 or 5. In preliminary immune analysis (16 patients), IGFBP-2 specific T-cell precursor frequencies are significantly elevated over baseline levels at 4 (p&lt;0.01) and 6 (p&lt;0.001) months. T-regulatory cells were not increased over the levels measured in a control reference population. No patients developed new IGFBP-2 specific antibody responses after immunization suggesting a lack of Th2 augmentation. Median OS for the matched SEER group (n=754) was 11 months. Matched IGFBP-2 vaccinated patients (n=20) have yet to reach median OS, but the lower 95% confidence limit is 27.3 months (p&lt;0.0001).

CONCLUSIONS: IGFBP-2 Th1 selective immunization is well tolerated, generates significant Type I immunity, and may demonstrate clinical efficacy.

Citation Format: John B. Liao, Denise L. Cecil, Yushe Dang, Kelsey K. Baker, Kelsie J. Ovenell, Jessica Reichow, Stephanie Parker, Doreen M. Higgins, Jennifer S. Childs, Elizabeth K. Broussard, Andrew L. Coveler, Lupe G. Salazar, Barbara A. Goff, Mary W. Redman, Mary L. Disis. VACCINATION TARGETING INSULIN–LIKE GROWTH FACTOR BINDING PROTEIN–2 (IGFBP–2) IN ADVANCED OVARIAN CANCER: SAFETY, IMMUNOGENICITY, AND SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS (SEER) COMPARISON [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr NTOC-097.

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.

Precancer Atlas to Drive Precision Prevention Trials

Cancer development is a complex process driven by inherited and acquired molecular and cellular alterations. Prevention is the holy grail of cancer elimination, but making this a reality will take a fundamental rethinking and deep understanding of premalignant biology. In this Perspective, we propose a national concerted effort to create a Precancer Atlas (PCA), integrating multi-omics and immunity - basic tenets of the neoplastic process. The biology of neoplasia caused by germline mutations has led to paradigm-changing precision prevention efforts, including: tumor testing for mismatch repair (MMR) deficiency in Lynch syndrome establishing a new paradigm, combinatorial chemoprevention efficacy in familial adenomatous polyposis (FAP), signal of benefit from imaging-based early detection research in high-germline risk for pancreatic neoplasia, elucidating early ontogeny in BRCA1-mutation carriers leading to an international breast cancer prevention trial, and insights into the intricate germline-somatic-immunity interaction landscape. Emerging genetic and pharmacologic (metformin) disruption of mitochondrial (mt) respiration increased autophagy to prevent cancer in a Li-Fraumeni mouse model (biology reproduced in clinical pilot) and revealed profound influences of subtle changes in mt DNA background variation on obesity, aging, and cancer risk. The elaborate communication between the immune system and neoplasia includes an increasingly complex cellular microenvironment and dynamic interactions between host genetics, environmental factors, and microbes in shaping the immune response. Cancer vaccines are in early murine and clinical precancer studies, building on the recent successes of immunotherapy and HPV vaccine immune prevention. Molecular monitoring in Barrett's esophagus to avoid overdiagnosis/treatment highlights an important PCA theme. Next generation sequencing (NGS) discovered age-related clonal hematopoiesis of indeterminate potential (CHIP). Ultra-deep NGS reports over the past year have redefined the premalignant landscape remarkably identifying tiny clones in the blood of up to 95% of women in their 50s, suggesting that potentially premalignant clones are ubiquitous. Similar data from eyelid skin and peritoneal and uterine lavage fluid provide unprecedented opportunities to dissect the earliest phases of stem/progenitor clonal (and microenvironment) evolution/diversity with new single-cell and liquid biopsy technologies. Cancer mutational signatures reflect exogenous or endogenous processes imprinted over time in precursors. Accelerating the prevention of cancer will require a large-scale, longitudinal effort, leveraging diverse disciplines (from genetics, biochemistry, and immunology to mathematics, computational biology, and engineering), initiatives, technologies, and models in developing an integrated multi-omics and immunity PCA - an immense national resource to interrogate, target, and intercept events that drive oncogenesis. Cancer Res; 77(7); 1510-41. ©2017 AACR.

Immunotherapy of head and neck cancer: Emerging clinical trials from a National Cancer Institute Head and Neck Cancer Steering Committee Planning Meeting

Recent advances have permitted successful therapeutic targeting of the immune system in head and neck squamous cell carcinoma (HNSCC). These new immunotherapeutic targets and agents are being rapidly adopted by the oncologic community and hold considerable promise. The National Cancer Institute sponsored a Clinical Trials Planning Meeting to address the issue of how to further investigate the use of immunotherapy in patients with HNSCC. The goals of the meeting were to consider phase 2 or 3 trial designs primarily in 3 different patient populations: those with previously untreated, human papillomavirus-initiated oropharyngeal cancers; those with previously untreated, human papillomavirus-negative HNSCC; and those with recurrent/metastatic HNSCC. In addition, a separate committee was formed to develop integrative biomarkers for the clinical trials. The meeting started with an overview of key immune components and principles related to HNSCC, including immunosurveillance and immune escape. Four clinical trial concepts were developed at the meeting integrating different immunotherapies with existing standards of care. These designs were presented for implementation by the head and neck committees of the National Cancer Institute-funded National Clinical Trials Network. This article summarizes the proceedings of this Clinical Trials Planning Meeting, the purpose of which was to facilitate the rigorous development and design of randomized phase 2 and 3 immunotherapeutic trials in patients with HNSCC. Although reviews usually are published immediately after the meeting is held, this report is unique because there are now tangible clinical trial designs that have been funded and put into practice and the studies are being activated to accrual. Cancer 2017;123:1259-1271. © 2016 American Cancer Society.