Validation of biomarkers to predict response to immunotherapy in cancer: Volume I - pre-analytical and analytical validation

Immunotherapies have emerged as one of the most promising approaches to treat patients with cancer. Recently, there have been many clinical successes using checkpoint receptor blockade, including T cell inhibitory receptors such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death-1 (PD-1). Despite demonstrated successes in a variety of malignancies, responses only typically occur in a minority of patients in any given histology. Additionally, treatment is associated with inflammatory toxicity and high cost. Therefore, determining which patients would derive clinical benefit from immunotherapy is a compelling clinical question.

Although numerous candidate biomarkers have been described, there are currently three FDA-approved assays based on PD-1 ligand expression (PD-L1) that have been clinically validated to identify patients who are more likely to benefit from a single-agent anti-PD-1/PD-L1 therapy. Because of the complexity of the immune response and tumor biology, it is unlikely that a single biomarker will be sufficient to predict clinical outcomes in response to immune-targeted therapy. Rather, the integration of multiple tumor and immune response parameters, such as protein expression, genomics, and transcriptomics, may be necessary for accurate prediction of clinical benefit. Before a candidate biomarker and/or new technology can be used in a clinical setting, several steps are necessary to demonstrate its clinical validity. Although regulatory guidelines provide general roadmaps for the validation process, their applicability to biomarkers in the cancer immunotherapy field is somewhat limited. Thus, Working Group 1 (WG1) of the Society for Immunotherapy of Cancer (SITC) Immune Biomarkers Task Force convened to address this need. In this two volume series, we discuss pre-analytical and analytical (Volume I) as well as clinical and regulatory (Volume II) aspects of the validation process as applied to predictive biomarkers for cancer immunotherapy. To illustrate the requirements for validation, we discuss examples of biomarker assays that have shown preliminary evidence of an association with clinical benefit from immunotherapeutic interventions. The scope includes only those assays and technologies that have established a certain level of validation for clinical use (fit-for-purpose). Recommendations to meet challenges and strategies to guide the choice of analytical and clinical validation design for specific assays are also provided.

Validation of biomarkers to predict response to immunotherapy in cancer: Volume II - clinical validation and regulatory considerations

There is growing recognition that immunotherapy is likely to significantly improve health outcomes for cancer patients in the coming years. Currently, while a subset of patients experience substantial clinical benefit in response to different immunotherapeutic approaches, the majority of patients do not but are still exposed to the significant drug toxicities. Therefore, a growing need for the development and clinical use of predictive biomarkers exists in the field of cancer immunotherapy. Predictive cancer biomarkers can be used to identify the patients who are or who are not likely to derive benefit from specific therapeutic approaches. In order to be applicable in a clinical setting, predictive biomarkers must be carefully shepherded through a step-wise, highly regulated developmental process. Volume I of this two-volume document focused on the pre-analytical and analytical phases of the biomarker development process, by providing background, examples and "good practice" recommendations. In the current Volume II, the focus is on the clinical validation, validation of clinical utility and regulatory considerations for biomarker development. Together, this two volume series is meant to provide guidance on the entire biomarker development process, with a particular focus on the unique aspects of developing immune-based biomarkers. Specifically, knowledge about the challenges to clinical validation of predictive biomarkers, which has been gained from numerous successes and failures in other contexts, will be reviewed together with statistical methodological issues related to bias and overfitting. The different trial designs used for the clinical validation of biomarkers will also be discussed, as the selection of clinical metrics and endpoints becomes critical to establish the clinical utility of the biomarker during the clinical validation phase of the biomarker development. Finally, the regulatory aspects of submission of biomarker assays to the U.S. Food and Drug Administration as well as regulatory considerations in the European Union will be covered.

Proceedings of the 2016 China Cancer Immunotherapy Workshop

A1 Proceedings of 2016 China Cancer Immunotherapy Workshop, Beijing, China

Bin Xue, Jiaqi Xu, Wenru Song, Zhimin Yang, Ke Liu, Zihai Li

A2 Set the stage: fundamental immunology in forty minutes

Zihai Li

A3 What have we learnt from the anti-PD-1/PD-L1 therapy of advanced human cancer?

Lieping Chen

A4 Immune checkpoint inhibitors in lung cancer

Edward B. Garon

A5 Mechanisms of response and resistance to checkpoint inhibitors in melanoma

Siwen Hu-Lieskovan

A6 Checkpoint inhibitor immunotherapy in lymphoid malignancies

Wei Ding

A7 Translational research to improve the efficacy of immunotherapy in genitourinary malignancies

Chong-Xian Pan

A8 Immune checkpoint inhibitors in gastrointestinal malignancies

Weijing Sun

A9 What’s next beyond PD-1/PDL1?

Yong-Jun Liu

A10 Cancer vaccines: new insights into the oldest immunotherapy strategy

Lei Zheng

A11 Bispecific antibodies for cancer immunotherapy

Delong Liu

A12 Updates on CAR-T immunotherapy

Michel Sadelain

A13 Adoptive T cell therapy: personalizing cancer treatment

Cassian Yee

A14 Immune targets and neoantigens for cancer immunotherapy

Rongfu Wang

A15 Phase I/IIa trial of chimeric antigen receptor modified T cells against CD133 in patients with advanced and metastatic solid tumors

Meixia Chen, Yao Wang, Zhiqiang Wu, Hanren Dai, Can Luo, Yang Liu, Chuan Tong, Yelei Guo, Qingming Yang, Weidong Han

A16 Cancer immunotherapy biomarkers: progress and issues

Lisa H. Butterfield

A17 Shaping of immunotherapy response by cancer genomes

Timothy A. Chan

A18 Unique development consideration for cancer immunotherapy

Wenru Song

A19 Immunotherapy combination

Ruirong Yuan

A20 Immunotherapy combination with radiotherapy

Bo Lu

A21 Cancer immunotherapy: past, present and future

Ke Liu

A22 Breakthrough therapy designation drug development and approval

Max Ning

A23 Current European regulation of innovative oncology medicines: opportunities for immunotherapy

Harald Enzmann, Heinz Zwierzina

Society for immunotherapy of cancer (SITC) statement on the proposed changes to the common rule

The Common Rule is a set of ethical principles that provide guidance on the management of human subjects taking part in biomedical and behavioral research in the United States. The elements of the Common Rule were initially developed in 1981 following a revision of the Declaration of Helsinki in 1975. Most academic facilities follow the Common Rule in the regulation of clinical trials research. Recently, the government has suggested a revision of the Common Rule to include more contemporary and streamlined oversight of clinical research. In this commentary, the leadership of the Society for Immunotherapy of Cancer (SITC) provides their opinion on this plan. While the Society recognizes the considerable contribution of clinical research in supporting progress in tumor immunotherapy and supports the need for revisions to the Common Rule, there is also some concern over certain elements which may restrict access to biospecimens and clinical data at a time when high throughput technologies, computational biology and assay standardization is allowing major advances in understanding cancer biology and providing potential predictive biomarkers of immunotherapy response. The Society values its professional commitment to patients for improving clinical outcomes with tumor immunotherapy and supports continued discussion with all stakeholders before implementing changes to the Common Rule in order to ensure maximal patient protections while promoting continued clinical research at this historic time in cancer research.

Phenotypic and functional testing of circulating regulatory T cells in advanced melanoma patients treated with neoadjuvant ipilimumab

Background

We have previously investigated neoadjuvant ipilimumab (ipi) for patients with locally/regionally advanced melanoma. That initial assessment of peripheral blood mononuclear cells (PBMC) showed a significant increase in shared tumor associated antigen specific CD4⁺ and CD8⁺ T cell activation. We also observed a transient increase in circulating T regulatory cells (Treg) with a parallel increase in total CD4⁺ T cells, as well as a significant decrease in circulating myeloid derived suppressor cells (MDSC). The increase in circulating Treg frequency, as assessed at 6 weeks after initiation of ipilimumab, was significantly associated with improved progression free survival (PFS, p = 0.034; HR = 0.57) and returned to baseline levels by 12 weeks. To shed light on the unexpected positive correlation between increased Treg and PFS, we here investigated the suppressive activity of circulating Treg at baseline and 6 weeks.

Methods

Patients were treated with ipi (10 mg/kg intravenously every 3 weeks for 2 doses) bracketing definitive surgery. Treg (CD4⁺CD25⁺CD127^dim/-) were isolated from pre-ipi (baseline) and post-ipi (6 weeks) PBMC samples. Treg were co-cultured with autologous responder CD4⁺ T cells that were stimulated with OKT3/IL-2/CD28 and CFSE-labeled T cells. 1:1, 1:2, and 1:5 ratios were tested. Flow cytometery was used to evaluate the degree of Treg proliferation suppression.

Results

Thirty-five patients were enrolled in the study; 18 patients had adequate PBMC samples with sufficient Treg isolated for Treg functional analysis. At 6 weeks following ipi, a decrease in percent of maximal inhibition of Th by Treg compared to baseline was seen for some patients. Scatter plot analysis showed no association between Treg frequency and function at any ratio or between circulating Treg frequency and function at baseline and at 6 weeks post-ipi. An increase in Treg suppressive function was significantly associated with a decrease in PFS (p = 0.02).

Conclusions

We find that Treg frequency measures do not correlate with suppressive activity measured ex vivo. Treg suppressive activity increases correlate with poorer patient outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-016-0141-1) contains supplementary material, which is available to authorized users.

Functional reprograming of chemokine microenvironment in colorectal cancer to promote intratumoral accumulation of immune effector cells

Infiltration of tumor lesions with effector CD8+ T cells (CTLs) has been shown to predict improved clinical outcomes in multiple cancer types and predict patients’ responsiveness to checkpoint blockers. In contrast, local prevalence of regulatory T(reg) cells has been shown to be a negative prognostic factor.

To correct the balance between intratumoral CTLs and Tregs in patients with advanced cancer, we developed a combinatorial approach to modify the balance between the CTL- and Treg-attracting chemokines in tumor tissues. Our preclinical studies in ex vivo tissue explant culture- and mouse tumor models, showed that TLR3 ligands combined with IFNα and PGE2 antagonists can reprogram tumor microenvironments to selectively promote the accumulation of CTLs and suppress Treg attraction.

Based on these preclinical data, we developed a phase I/II clinical trial (UPCI 10-131/NCT01545141), to determine the safety and local effectiveness of the intravenous infusion of Rintatolimod (selective TLR3 ligand) combined with Intron A and oral celecoxib, in patients with resectable recurrent colorectal cancer. In the completed phase I of this trial, we observed very good safety profile of this combination and, in accordance with our expectations, selective reduction in the markers of CTLs, TH1- and NK cells in circulation, lasting 24–48 hours after Rintatolimod and Intron A infusion. Comparison of the resected tumors demonstrated an enhanced ratio of CXCL10 (CTL-attractant) to CCL22 (Treg-attractant) and an increased ratio of CD8α (CTL marker) to FoxP3 (Treg marker), in the chemokine modulation cohort, compared to patients receiving standard care at our center (non-randomized control). The randomized phase II portion of the trial is ongoing.

Prolonged intralymphatic delivery of dendritic cells through implantable lymphatic ports in patients with advanced cancer

Background

The currently-used modes of administration of immunotherapeutic agents result in their limited delivery to the lymph nodes and/or require repetitive ultrasound-guided nodal injections or microsurgical lymphatic injections, limiting their feasibility. Here, we report on the feasibility and safety of a new method of long-term repetitive intralymphatic (IL) infusion of immune cells, using implantable delivery ports.

Methods

Nine patients with stage IV recurrent colorectal cancer underwent complete resection and received autologous dendritic cells (DCs) loaded with killed autologous tumor cells, KLH and PADRE, for up to four monthly cycles. Leg lymphatic vessels were cannulated, connected to 6.6Fr low-profile implantable subcutaneous delivery ports, and used to infuse 12 doses of DC over each 72 h-long cycle (every 6 h), followed by heparin flushes of the cannula-port system (one 72 h-long cycle per month). The patients who opted for alternative route of vaccine administration (2 patients) or whose ports became non-functional between cycles, continued treatment via intranodal (one injection/cycle) or intradermal (four injections/cycle) routes.

Results

A total of nine lymphatic cannulations and implantations of subcutaneous delivery ports were attempted in seven patients, with a success rate of eight out of nine (89 %). The average patency of the IL delivery system was 7.5 (±3.2) weeks. All six patients with IL ports successfully completed at least one complete 72 h-long DC infusion cycle (12 injections). Five patients (56 %) completed two full IL cycles (24 IL injections). No patients received more than two IL cycles without replacement of the IL port, due to catheter occlusion and/or local side effects: cellulitis and hematoma. Intranodal and intradermal backup options were used in, respectively, one and two patients. Overall cohort survival was >28 (±25) months. One patient with aggressive recurrent carcinomatosis, who received DC vaccines by intranodal route is alive at > 90 months, without evidence of disease.

Conclusions

We conclude that an intermediate-duration IL delivery of multiple doses of immunotherapeutic factors using implantable delivery ports is feasible, highly-tolerable and can be reproducibly performed in cancer patients to administer immune cells, or potentially, other immune factors. However, long-term IL port placement (>7.5 weeks), is not a currently-feasible option.

Trial registration

NCT00558051, registered Nov. 13, 2007.

Web-based collaborative care intervention to manage cancer-related symptoms in the palliative care setting

BACKGROUND

The aim of this study was to examine the efficacy of a collaborative care intervention in reducing depression, pain, and fatigue and improve quality of life.

METHODS

A total of 261 patients with advanced cancer and 179 family caregivers were randomized to a web-based collaborative care intervention or enhanced usual care. The intervention included the following: 1) a web site with written and audiovisual self-management strategies, a bulletin board, and other resources; 2) visits with a care coordinator during a physician's appointment every 2 months; and 3) telephone follow-up every 2 weeks. Primary patient outcomes included measures of depression, pain, fatigue, and health-related quality of life. Secondary outcomes included Interleukin (IL)-1α, IL-1β, IL-6, and IL-8 levels, Natural Killer (NK) cell numbers, and caregiver stress and depression.

RESULTS

At the baseline, 51% of the patients reported 1 or more symptoms in the clinical range. For patients who presented with clinical levels of symptoms and were randomized to the intervention, reductions in depression (Cohen's d = 0.71), pain (Cohen's d = 0.62), and fatigue (Cohen's d = 0.26) and improvements in quality of life (Cohen's d = 0.99) were observed when compared to those in the enhanced usual car arm at 6 months. Reductions in IL-6 (φ = 0.18), IL-1β (φ = 0.35), IL-1α (φ = 0.19), and IL-8 (φ = 0.15) and increases in NK cell numbers (φ = 0.23) were observed in comparison with enhanced usual care arm at 6 months. Reductions in caregiver stress (Cohen's d = 0.75) and depression (Cohen's d = 0.37) were observed at 6 months for caregivers whose loved ones were randomized to the intervention arm.

CONCLUSIONS

The integration of screening and symptom management into cancer care is recommended.

Immune responses and outcome after vaccination with glioma-associated antigen peptides and poly-ICLC in a pilot study for pediatric recurrent low-grade gliomas

BACKGROUND

Low-grade gliomas (LGGs) are the most common brain tumors of childhood. Although surgical resection is curative for well-circumscribed superficial lesions, tumors that are infiltrative or arise from deep structures are therapeutically challenging, and new treatment approaches are needed. Having identified a panel of glioma-associated antigens (GAAs) overexpressed in these tumors, we initiated a pilot trial of vaccinations with peptides for GAA epitopes in human leukocyte antigen-A2+ children with recurrent LGG that had progressed after at least 2 prior regimens.

METHODS

Peptide epitopes for 3 GAAs (EphA2, IL-13Rα2, and survivin) were emulsified in Montanide-ISA-51 and administered subcutaneously adjacent to intramuscular injections of polyinosinic-polycytidylic acid stabilized by lysine and carboxymethylcellulose every 3 weeks for 8 courses, followed by booster vaccines every 6 weeks. Primary endpoints were safety and T-lymphocyte responses against GAA epitopes. Treatment response was evaluated clinically and by MRI.

RESULTS

Fourteen children were enrolled. Other than grade 3 urticaria in one child, no regimen-limiting toxicity was encountered. Vaccination induced immunoreactivity to at least one vaccine-targeted GAA in all 12 evaluable patients: to IL-13Rα2 in 3, EphA2 in 11, and survivin in 3. One child with a metastatic LGG had asymptomatic pseudoprogression noted 6 weeks after starting vaccination, followed by dramatic disease regression with >75% shrinkage of primary tumor and regression of metastatic disease, persisting >57 months. Three other children had sustained partial responses, lasting >10, >31, and >45 months, and one had a transient response.

CONCLUSIONS

GAA peptide vaccination in children with recurrent LGGs is generally well tolerated, with preliminary evidence of immunological and clinical activity.

Lessons learned from cancer vaccine trials and target antigen choice

A wide variety of tumor antigens have been targeted in cancer immunotherapy studies. Traditionally, the focus has been on commonly overexpressed antigens shared across many patients and/or tumor types. As the field has progressed, the identity of human tumor rejection antigens has broadened. Immunologic monitoring of clinical trials has slowly elucidated candidate biomarkers of immune response and clinical response, and conversely, of immune dysfunction and suppression. We have utilized MART-1/Melan-A in our melanoma studies and observed a high frequency of immune responses and several significant clinical responses in patients vaccinated with this melanosomal protein. Alpha-fetoprotein is a shared, overexpressed tumor antigen and secreted glycoprotein that we have tested in hepatocellular cancer vaccines. Our recent studies have identified immunosuppressive and immune-skewing activities of this antigen. The choice of target antigen and its form can have unexpected effects.

Prospective Clinical Testing of Regulatory Dendritic Cells in Organ Transplantation

Dendritic cells (DC) are rare, professional antigen-presenting cells with ability to induce or regulate alloimmune responses. Regulatory DC (DCreg) with potential to down-modulate acute and chronic inflammatory conditions that occur in organ transplantation can be generated in vitro under a variety of conditions. Here, we provide a rationale for evaluation of DCreg therapy in clinical organ transplantation with the goal of promoting sustained, donor-specific hyporesponsiveness, while lowering the incidence and severity of rejection and reducing patients’ dependence on anti-rejection drugs. Generation of donor- or recipient-derived DCreg that suppress T cell responses and prolong transplant survival in rodents or non-human primates has been well-described. Recently, good manufacturing practice (GMP)-grade DCreg have been produced at our Institution for prospective use in human organ transplantation. We briefly review experience of regulatory immune therapy in organ transplantation and describe our experience generating and characterizing human monocyte-derived DCreg. We propose a phase I/II safety study in which the influence of donor-derived DCreg combined with conventional immunosuppression on subclinical and clinical rejection and host alloimmune responses will be examined in detail.

Novel technologies and emerging biomarkers for personalized cancer immunotherapy

The culmination of over a century's work to understand the role of the immune system in tumor control has led to the recent advances in cancer immunotherapies that have resulted in durable clinical responses in patients with a variety of malignancies. Cancer immunotherapies are rapidly changing traditional treatment paradigms and expanding the therapeutic landscape for cancer patients. However, despite the current success of these therapies, not all patients respond to immunotherapy and even those that do often experience toxicities. Thus, there is a growing need to identify predictive and prognostic biomarkers that enhance our understanding of the mechanisms underlying the complex interactions between the immune system and cancer. Therefore, the Society for Immunotherapy of Cancer (SITC) reconvened an Immune Biomarkers Task Force to review state of the art technologies, identify current hurdlers, and make recommendations for the field. As a product of this task force, Working Group 2 (WG2), consisting of international experts from academia and industry, assembled to identify and discuss promising technologies for biomarker discovery and validation. Thus, this WG2 consensus paper will focus on the current status of emerging biomarkers for immune checkpoint blockade therapy and discuss novel technologies as well as high dimensional data analysis platforms that will be pivotal for future biomarker research. In addition, this paper will include a brief overview of the current challenges with recommendations for future biomarker discovery.

Novel technologies and emerging biomarkers for personalized cancer immunotherapy

The culmination of over a century’s work to understand the role of the immune system in tumor control has led to the recent advances in cancer immunotherapies that have resulted in durable clinical responses in patients with a variety of malignancies. Cancer immunotherapies are rapidly changing traditional treatment paradigms and expanding the therapeutic landscape for cancer patients. However, despite the current success of these therapies, not all patients respond to immunotherapy and even those that do often experience toxicities. Thus, there is a growing need to identify predictive and prognostic biomarkers that enhance our understanding of the mechanisms underlying the complex interactions between the immune system and cancer. Therefore, the Society for Immunotherapy of Cancer (SITC) reconvened an Immune Biomarkers Task Force to review state of the art technologies, identify current hurdlers, and make recommendations for the field. As a product of this task force, Working Group 2 (WG2), consisting of international experts from academia and industry, assembled to identify and discuss promising technologies for biomarker discovery and validation. Thus, this WG2 consensus paper will focus on the current status of emerging biomarkers for immune checkpoint blockade therapy and discuss novel technologies as well as high dimensional data analysis platforms that will be pivotal for future biomarker research. In addition, this paper will include a brief overview of the current challenges with recommendations for future biomarker discovery.

Randomized, Placebo-Controlled, Phase III Trial of Yeast-Derived Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Versus Peptide Vaccination Versus GM-CSF Plus Peptide Vaccination Versus Placebo in Patients With No Evidence of Disease After Complete Surgical Resection of Locally Advanced and/or Stage IV Melanoma: A Trial of the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network Cancer Research Group (E4697)

PURPOSE

We conducted a double-blind, placebo-controlled trial to evaluate the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) and peptide vaccination (PV) on relapse-free survival (RFS) and overall survival (OS) in patients with resected high-risk melanoma.

PATIENTS AND METHODS

Patients with completely resected stage IV or high-risk stage III melanoma were grouped by human leukocyte antigen (HLA) -A2 status. HLA-A2-positive patients were randomly assigned to receive GM-CSF, PV, both, or placebo; HLA-A2-negative patients, GM-CSF or placebo. Treatment lasted for 1 year or until recurrence. Efficacy analyses were conducted in the intent-to-treat population.

RESULTS

A total of 815 patients were enrolled. There were no significant improvements in OS (stratified log-rank P = .528; hazard ratio, 0.94; 95% repeated CI, 0.77 to 1.15) or RFS (P = .131; hazard ratio, 0.88; 95% CI, 0.74 to 1.04) in the patients assigned to GM-CSF (n = 408) versus those assigned to placebo (n = 407). The median OS times with GM-CSF versus placebo treatments were 69.6 months (95% CI, 53.4 to 83.5 months) versus 59.3 months (95% CI, 44.4 to 77.3 months); the 5-year OS probability rates were 52.3% (95% CI, 47.3% to 57.1%) versus 49.4% (95% CI, 44.3% to 54.3%), respectively. The median RFS times with GM-CSF versus placebo were 11.4 months (95% CI, 9.4 to 14.8 months) versus 8.8 months (95% CI, 7.5 to 11.2 months); the 5-year RFS probability rates were 31.2% (95% CI, 26.7% to 35.9%) versus 27.0% (95% CI, 22.7% to 31.5%), respectively. Exploratory analyses showed a trend toward improved OS in GM-CSF-treated patients with resected visceral metastases. When survival in HLA-A2-positive patients who received PV versus placebo was compared, RFS and OS were not significantly different. Treatment-related grade 3 or greater adverse events were similar between GM-CSF and placebo groups.

CONCLUSION

Neither adjuvant GM-CSF nor PV significantly improved RFS or OS in patients with high-risk resected melanoma. Exploratory analyses suggest that GM-CSF may be beneficial in patients with resected visceral metastases; this observation requires prospective validation.

Baseline circulating IL-17 predicts toxicity while TGF-β1 and IL-10 are prognostic of relapse in ipilimumab neoadjuvant therapy of melanoma

Background

We evaluated candidate circulating serum cytokines, chemokines and growth factors in patients with locally/regionally advanced melanoma receiving neoadjuvant ipilimumab with toxicity and clinical outcome.

Methods

Patients were treated with ipilimumab (10 mg/kg IV every 3 weeks, 2 doses) before and after surgery. xMAP multiplex serum testing for 36 functionally selected cytokines and chemokines was performed at baseline and at six weeks (following ipilimumab). Based on our prior data, the association of IL-17 and immune related colitis was tested. Serum cytokines were divided into functional groups (Th1, Th2, Regulatory, Proinflammatory) and were assessed at baseline and week 6 using sparse-group Lasso modeling to assess the association of various cytokine groups with progression free survival (PFS). The linear combination of the cytokines/chemokines in this model was then used as a risk score and a Kaplan-Meier curve was generated to examine the association of the dichotomized score and PFS.

Results

Thirty-five patients were enrolled whose staging was: IIIB (3; N2b), IIIC (30; N2c, N3), IV (2). Median follow-up was 18 months. Among 33 evaluable patients, median PFS was 11 months (95 % CI = 6.2–19.2). IL-17 was found to correlate significantly with the incidence of grade 3 diarrhea/colitis when measured at baseline (p = 0.02) with a trend towards significance at 6 weeks (p = 0.06). In the modeling analysis, at baseline, the linear combination of 2 regulatory cytokines [TGF- β1 (ρ = 0.19) and IL-10 (ρ = -0.34)] was significantly associated with PFS (HR 2.66; p = 0.035). No significant correlations with clinical outcomes were found in examining the week 6 cytokines.

Conclusions

Baseline IL-17 level was significantly associated with the later development of severe diarrhea/colitis while the combination of baseline TGF- β1 and IL-10 levels were associated with therapeutic clinical outcome after neoadjuvant ipilimumab. These findings warrant further investigation and validation.

Trial registration

ClinicalTrials.gov Identifier NCT00972933.

Abstract 4302: Long term monitoring of circulating regulatory T cells (Treg), myeloid derived suppressor cella (MDSC) and type I effector T cells in melanoma patients treated with neoadjuvant ipilimumab

Background: Patients with regionally advanced melanoma were treated with neoadjuvant ipilimumab in a previously reported study (Tarhini. PLOS One 2014) where significant changes in circulating Treg, MDSC and peptide specific type I CD4+ and CD8+ T cells were observed early on-treatment (6 weeks) that correlated with clinical outcome.

Methods: Patients were treated with ipilimumab (10 mg/kg IV every 3 weeks x 2 doses) bracketing surgery. Blood (serum / peripheral blood mononuclear cells) specimens were collected at baseline and during treatment for up to 9 months. We conducted longer term monitoring in patients with available specimens at 3 (n = 28), 6 (n = 22) and 9 (n = 13) months utilizing multicolor flow cytometry. We compared the frequencies of circulating suppressive Treg and MDSC on-study to baseline levels, as well as frequencies of CD4+ and CD8+ T cells specific to shared tumor-associated antigens (Gp-100, MART-1, NY-ESO-1) utilizing overlapping peptide libraries (15-mer peptides overlapping by 4). The prognostic value of cell frequencies in relation to the probability of the event of progression at 9 months was tested.

Results: Baseline levels of Treg (CD4+/CD25hi+/CD39+) were significantly associated with 9 months progression free survival (PFS) (p = 0.04). A significant increase in Treg (CD4+CD25hi+Foxp3+ and CD4+/CD25hi+/CD39+) frequencies reported previously at 6 weeks after initiation of ipilimumab appears to have reversed starting 3 months as no significant changes were seen at this or any of the later time points compared to baseline. However, in monitoring the time dependent change over time in circulating Treg there was a trend towards an association with PFS (p = 0.09). Unlike what we had observed and reported at 6 weeks, no significant decrease in MDSC levels was seen at 3 months or later time points compared to baseline. We detected evidence of spontaneous in vivo cross presentation resulting in type I (interferon-γ producing), fully activated (CD69+) CD4+ and CD8+ antigen-specific T-cell immunity against cancer-testis (NY-ESO-1) as well as melanocytic lineage (MART-1, gp100) antigens in the absence of therapeutic vaccination. These responses were significantly potentiated at 6 weeks and persisted at 3, 6 and 9 months following the initiation of ipilimumab.

Conclusions: Neoadjuvant ipilimumab significantly modulates the levels of cellular mediators of immune suppression (Treg and MDSC) early on-treatment with less significant changes seen on long term follow up. Significant potentiation of the type I effector T cell response is seen early and persists on long term monitoring. These biomarkers warrant further investigation in relation to the mechanism of action of ipilimumab and for their potential prognostic and therapeutic predictive value. (Supported by NIH award P50CA121973 and BMS)

Citation Format: Janet Retseck, Amanda Gillespie-Twardy, Alexis Nasr, Hui-Min Lin, Yan Lin, John Kirkwood, Lisa H. Butterfield, Haris Zahoor, Cindy Sander, Ahmad A. Tarhini. Long term monitoring of circulating regulatory T cells (Treg), myeloid derived suppressor cella (MDSC) and type I effector T cells in melanoma patients treated with neoadjuvant ipilimumab. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4302. doi:10.1158/1538-7445.AM2015-4302

Route of antigen delivery impacts the immunostimulatory activity of dendritic cell-based vaccines for hepatocellular carcinoma

Background

Dendritic cells (DC) are uniquely equipped to capture, process, and present antigens from their environment. The context in which an antigen is acquired by DC helps to dictate the subsequent immune response. Cancer vaccination promotes antitumor immunity by directing an immune response to antigens expressed by tumors. We have tested the tumor-associated antigen alpha-fetoprotein (AFP) as an immunotherapy target. The majority of hepatocellular carcinomas (HCC) upregulate and secrete this oncofetal antigen.

Methods

To develop cancer vaccines for HCC capable of promoting potent tumor-specific T cell responses, we tested adenovirally-encoded synthetic AFP, with or without its signal sequence, as well as protein forms of AFP and compared intracellular routing and subsequent antigen-specific CD8+ and CD4+ T cell responses.

Results

Surprisingly, the secreted form of antigen was superior for both CD4+ and CD8+ T cell activation. We also examined the mechanism through which AFP protein is endocytosed and trafficked in human DC. We identify the mannose receptor (MR/CD206) as the primary uptake pathway for both normal cord blood-derived AFP (nAFP) and tumor-derived AFP (tAFP) proteins. While in healthy donors, nAFP and tAFP were cross-presented to CD8+ T cells similarly and CD4+ T cell responses were dependent upon MR-mediated uptake. In HCC patient cells, tAFP was more immunogenic, and CD4+ T cell responses were not MR-dependent.

Conclusions

Secreted, cytoplasmically retained, and endocytosed forms of AFP utilize unique uptake and processing pathways, resulting in different immunologic responses from the induced antigen-specific CD4+ and CD8+ T cells and between healthy donors and HCC patients. Collectively, these data elucidate pathways of spontaneous and induced anti-tumor immunity in HCC patients to this secreted antigen.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-015-0077-x) contains supplementary material, which is available to authorized users.