Peripheral immune cells in metastatic breast cancer patients display a systemic immunosuppressed signature consistent with chronic inflammation

Immunotherapies blocking the PD-1/PD-L1 checkpoint show some efficacy in metastatic breast cancer (mBC) but are often hindered by immunosuppressive mechanisms. Understanding these mechanisms is crucial for personalized treatments, with peripheral blood monitoring representing a practical alternative to repeated biopsies. In the present study, we performed a comprehensive mass cytometry analysis of peripheral blood immune cells in 104 patients with HER2 negative mBC and 20 healthy donors (HD). We found that mBC patients had significantly elevated monocyte levels and reduced levels of CD4+ T cells and plasmacytoid dendritic cells, when compared to HD. Furthermore, mBC patients had more effector T cells and regulatory T cells, increased expression of immune checkpoints and other activation/exhaustion markers, and a shift to a Th2/Th17 phenotype. Furthermore, T-cell phenotypes identified by mass cytometry correlated with functionality as assessed by IFN-γ production. Additional analysis indicated that previous chemotherapy and CDK4/6 inhibition impacted the numbers and phenotype of immune cells. From 63 of the patients, fresh tumor samples were analyzed by flow cytometry. Paired PBMC-tumor analysis showed moderate correlations between peripheral CD4+ T and NK cells with their counterparts in tumors. Further, a CD4+ T cell cluster in PBMCs, that co-expressed multiple checkpoint receptors, was negatively associated with CD4+ T cell tumor infiltration. In conclusion, the identified systemic immune signatures indicate an immune-suppressed environment in mBC patients who had progressed/relapsed on standard treatments, and is consistent with ongoing chronic inflammation. These activated immuno-suppressive mechanisms may be investigated as therapeutic targets, and for use as biomarkers of response or treatment resistance.

Ipilimumab and nivolumab combined with anthracycline-based chemotherapy in metastatic hormone receptor-positive breast cancer: a randomized phase 2b trial

BACKGROUND

Immune checkpoint inhibitors have shown minimal clinical activity in hormone receptor-positive metastatic breast cancer (HR+mBC). Doxorubicin and low-dose cyclophosphamide are reported to induce immune responses and counter regulatory T cells (Tregs). Here, we report the efficacy and safety of combined programmed cell death protein-1/cytotoxic T-lymphocyte-associated protein 4 blockade concomitant with or after immunomodulatory chemotherapy for HR+mBC.

METHODS

Patients with HR+mBC starting first-/second- line chemotherapy (chemo) were randomized 2:3 to chemotherapy (pegylated liposomal doxorubicin 20 mg/m2 every second week plus cyclophosphamide 50 mg by mouth/day in every other 2-week cycle) with or without concomitant ipilimumab (ipi; 1 mg/kg every sixth week) and nivolumab (nivo; 240 mg every second week). Patients in the chemo-only arm were offered cross-over to ipi/nivo without chemotherapy. Co-primary endpoints were safety in all patients starting therapy and progression-free survival (PFS) in the per-protocol (PP) population, defined as all patients evaluated for response and receiving at least two treatment cycles. Secondary endpoints included objective response rate, clinical benefit rate, Treg changes during therapy and assessment of programmed death-ligand 1 (PD-L1), mutational burden and immune gene signatures as biomarkers.

RESULTS

Eighty-two patients were randomized and received immune-chemo (N=49) or chemo-only (N=33), 16 patients continued to the ipi/nivo-only cross-over arm. Median follow-up was 41.4 months. Serious adverse events occurred in 63% in the immune-chemo arm, 39% in the chemo-only arm and 31% in the cross-over-arm. In the PP population (N=78) median PFS in the immune-chemo arm was 5.1 months, compared with 3.6 months in the chemo-only arm, with HR 0.94 (95% CI 0.59 to 1.51). Clinical benefit rates were 55% (26/47) and 48% (15/31) in the immune-chemo and chemo-only arms, respectively. In the cross-over-arm (ipi/nivo-only), objective responses were observed in 19% of patients (3/16) and clinical benefit in 25% (4/16). Treg levels in blood decreased after study chemotherapy. High-grade immune-related adverse events were associated with prolonged PFS. PD-L1 status and mutational burden were not associated with ipi/nivo benefit, whereas a numerical PFS advantage was observed for patients with a high Treg gene signature in tumor.

CONCLUSION

The addition of ipi/nivo to chemotherapy increased toxicity without improving efficacy. Ipi/nivo administered sequentially to chemotherapy was tolerable and induced clinical responses.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT03409198.

Comparative Evaluation of STEAP1 Targeting Chimeric Antigen Receptors with Different Costimulatory Domains and Spacers

We have developed a chimeric antigen receptor (CAR) against the six-transmembrane epithelial antigen of prostate-1 (STEAP1), which is expressed in prostate cancer, Ewing sarcoma, and other malignancies. In the present study, we investigated the effect of substituting costimulatory domains and spacers in this STEAP1 CAR. We cloned four CAR constructs with either CD28 or 4-1BB costimulatory domains, combined with a CD8a-spacer (sp) or a mutated IgG-spacer. The CAR T-cells were evaluated in short- and long-term in vitro T-cell assays, measuring cytokine production, tumor cell killing, and CAR T-cell expansion and phenotype. A xenograft mouse model of prostate cancer was used for in vivo comparison. All four CAR constructs conferred CD4+ and CD8+ T cells with STEAP1-specific functionality. A CD8sp_41BBz construct and an IgGsp_CD28z construct were selected for a more extensive comparison. The IgGsp_CD28z CAR gave stronger cytokine responses and killing in overnight caspase assays. However, the 41BB-containing CAR mediated more killing (IncuCyte) over one week. Upon six repeated stimulations, the CD8sp_41BBz CAR T cells showed superior expansion and lower expression of exhaustion markers (PD1, LAG3, TIGIT, TIM3, and CD25). In vivo, both the CAR T variants had comparable anti-tumor activity, but persisting CAR T-cells in tumors were only detected for the 41BBz variant. In conclusion, the CD8sp_41BBz STEAP1 CAR T cells had superior expansion and survival in vitro and in vivo, compared to the IgGsp_CD28z counterpart, and a less exhausted phenotype upon repeated antigen exposure. Such persistence may be important for clinical efficacy.

How I treat endocrine-dependent metastatic breast cancer

Estrogen receptor-positive (ER+)/HER2-negative (HER2-), the so-called luminal-type breast cancer, is the most frequent subset, accounting for around 70% of all breast cancer cases. Endocrine therapy (ET) combined with cyclin-dependent kinases (CDK) 4/6 inhibitors is the standard first option in the management of advanced luminal breast cancer independently of disease extension. Classically, patients undergo multiple lines of ET ± targeted treatments until endocrine resistance occurs and palliative chemotherapy is proposed. Understanding endocrine resistance mechanisms and development of novel ET options is one of the main challenges in current clinical research. Another area of utmost interest is the improvement of post-endocrine therapeutic approaches. Among others, the development of antibody-drug conjugates (ADCs) is very promising, and some of these drugs will probably soon become a part of the therapeutic arsenal against this incurable disease. This review paper provides an overview of currently available treatment options in ER+/HER2- metastatic breast cancer and extensively discusses new approaches in late clinical development.

Abstract PD11-11: PD11-11 Results from ALICE – Atezolizumab Combined with Immunogenic Chemotherapy in Patients with Metastatic Triple Negative Breast Cancer, a Randomized Phase IIb Trial

Background: Immune checkpoint inhibitors (CPI) have shown efficacy against metastatic triple negative breast cancer (mTNBC), but only for PD-L1 positive tumors. It is not known if so-called immunogenic chemotherapies may yield clinical relevant synergies with CPI. We addressed these issues, by conducting a trial evaluating atezolizumab (anti-PD-L1) in combination with doxorubicin, which has been reported to provoke immunogenic cell death, and low-dose metronomic cyclophosphamide, which has been reported to counter immunosuppressive cells. The pegylated liposomal form of doxorubicin (PLD) was selected to avoid steroids and allow for long term therapy in responders. To our knowledge, this is the first randomized trial reporting on the concomitant addition of CPI to antracyclines in mTNBC. Methods: The trial enrolled patients with mTNBC and maximum one previous line of chemotherapy in the metastatic setting. Patients were randomized 2:3 into arm A (n=28), receiving chemotherapy alone, or arm B (n=40), receiving chemotherapy in combination with atezolizumab (840 mg every 2nd week). The chemotherapy consisted of PLD (20mg/m2 every 2nd week) + oral cyclophosphamide (cyclo; 50mg/day, 2/4 weeks) in both arms. The per protocol (PP) population was defined as patients receiving > 3 doses of atezolizumab and >2 doses of PLD. The primary efficacy endpoint was progression-free survival (PFS) in the PP population. The protocol power analysis focused on durable response, as measured by 15 months PFS. Safety, a co-primary endpoint, was evaluated in all patients that started therapy (Full Analysis Set; FAS). Secondary endpoints included PFS in FAS, objective response rate (ORR), clinical benefit rate (CBR), durable response rate (>6 months; DRR), overall survival (OS) and biomarkers. PD-L1 status was determined retrospectively by the Ventana SP142 assay, as tumor-infiltrating immune cells with cut-off ≥ 1%. Efficacy data are given in the PP population unless stated otherwise. Hazard ratios (HR) are given with 95% confidence intervals (CI). Results: A total of 68 patients started therapy (FAS), of which 59 were in the PP population and 57% had not received previous chemotherapy in the metastatic setting. PFS was significantly improved in arm B compared to arm A in both the PP population (HR 0.57; CI 0.33-0.99; p=0.0477) and in the FAS (HR 0.56; CI 0.33-0.95; p=0.0326). Median PFS was 4.3 months in arm B versus 3.5 months in arm A. The progression-free proportion after 15 months was 14.7% (CI 6.4-30.1%) in arm B versus 0% in arm A. The ORR was 30.6%/21.7%, CBR was 52.8%/43.5% and DRR was 13.9%/4.3% in arm B/A. The PFS advantage was observed for both PD-L1+ (n=27; HR 0.58) and PD-L1- subjects (n=31; HR 0.66). All five patients without progression after 15 months belonged to arm B, and three out of these patients were PD-L1 negative. Serious adverse events occurred for 48% in arm B and 29% in arm A (FAS). The most common immune related adverse events of any grade in arm B/A were hypothyroidism (10.0%/7.1 %), pneumonitis (10.0%/3.6%), hyperthyroidism (5.0%/7.1%) and rash (7.5%/3.6%). Further biomarker analyses and assessments of immunological changes during therapy are ongoing. Conclusions: The addition of atezolizumab to PLD and low-dose metronomic cyclophosphamide significantly improved PFS. A benefit was indicated also in patients with PD-L1 negative disease. The combination regimen was well tolerated with no new safety signals. Results from the ongoing analyses of consecutive tumor and blood samples will be important to assess the hypothesized immunological effects of the chemotherapy and to investigate biomarkers associated with the response to the combined treatment.

Citation Format: Jon Amund Kyte, Andreas H. Røssevold, Nikolai K. Andresen, Christina Annette Bjerre, Bjørnar Gilje, Erik Hugger Jakobsen, Sunil Xavier Raj, Ragnhild Sørum Falk, Elin Borgen, Thea Jahr, Øystein Garred, Jon Lømo, Randi Margit Mathiesen, Bjørn Naume. PD11-11 Results from ALICE – Atezolizumab Combined with Immunogenic Chemotherapy in Patients with Metastatic Triple Negative Breast Cancer, a Randomized Phase IIb Trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD11-11.

Atezolizumab plus anthracycline-based chemotherapy in metastatic triple-negative breast cancer: the randomized, double-blind phase 2b ALICE trial

Immune checkpoint inhibitors have shown efficacy against metastatic triple-negative breast cancer (mTNBC) but only for PD-L1positive disease. The randomized, placebo-controlled ALICE trial ( NCT03164993 , 24 May 2017) evaluated the addition of atezolizumab (anti-PD-L1) to immune-stimulating chemotherapy in mTNBC. Patients received pegylated liposomal doxorubicin (PLD) and low-dose cyclophosphamide in combination with atezolizumab (atezo-chemo; n = 40) or placebo (placebo-chemo; n = 28). Primary endpoints were descriptive assessment of progression-free survival in the per-protocol population (>3 atezolizumab and >2 PLD doses; n = 59) and safety in the full analysis set (FAS; all patients starting therapy; n = 68). Adverse events leading to drug discontinuation occurred in 18% of patients in the atezo-chemo arm (7/40) and in 7% of patients in the placebo-chemo arm (2/28). Improvement in progression-free survival was indicated in the atezo-chemo arm in the per-protocol population (median 4.3 months versus 3.5 months; hazard ratio (HR) = 0.57; 95% confidence interval (CI) 0.33-0.99; log-rank P = 0.047) and in the FAS (HR = 0.56; 95% CI 0.33-0.95; P = 0.033). A numerical advantage was observed for both the PD-L1positive (n = 27; HR = 0.65; 95% CI 0.27-1.54) and PD-L1negative subgroups (n = 31; HR = 0.57, 95% CI 0.27-1.21). The progression-free proportion after 15 months was 14.7% (5/34; 95% CI 6.4-30.1%) in the atezo-chemo arm versus 0% in the placebo-chemo arm. The addition of atezolizumab to PLD/cyclophosphamide was tolerable with an indication of clinical benefit, and the findings warrant further investigation of PD1/PD-L1 blockers in combination with immunomodulatory chemotherapy.

Development of a High-Affinity Antibody against the Tumor-Specific and Hyperactive 611-p95HER2 Isoform

Simple Summary

In the present study, we addressed the unmet need for a molecular antibody (mAb) with high affinity and specificity against a truncated hyperactive isoform of human epidermal growth factor receptor 2 (HER2), called 611-carboxy terminal fragment (CTF)-p95HER2. Patients with p95HER2+ breast cancer are at risk of developing metastatic breast cancer with a poor prognosis and resistance to therapies targeting full-length HER2. We have generated a mAb named Oslo-2, which react specifically with 611-CTF-p95HER2 and has a high affinity. We also characterized the antigenic determinant (epitope) on the p95HER2 protein and the antigen-binding site (paratope) on the Oslo-2 mAb. The antibody can be used to develop antibody- or cell-based therapies targeting p95HER2, as well as a diagnostic assay to identify p95HER2+ disease.

Abstract

The expression of human epidermal growth factor receptor 2 (HER2) is a key classification factor in breast cancer. Many breast cancers express isoforms of HER2 with truncated carboxy-terminal fragments (CTF), collectively known as p95HER2. A common p95HER2 isoform, 611-CTF, is a biomarker for aggressive disease and confers resistance to therapy. Contrary to full-length HER2, 611-p95HER2 has negligible normal tissue expression. There is currently no approved diagnostic assay to identify this subgroup and no therapy targeting this mechanism of tumor escape. The purpose of this study was to develop a monoclonal antibody (mAb) against 611-CTF-p95HER2. Hybridomas were generated from rats immunized with cells expressing 611-CTF. A hybridoma producing a highly specific Ab was identified and cloned further as a mAb. This mAb, called Oslo-2, gave strong staining for 611-CTF and no binding to full-length HER2, as assessed in cell lines and tissues by flow cytometry, immunohistochemistry and immunofluorescence. No cross-reactivity against HER2 negative controls was detected. Surface plasmon resonance analysis demonstrated a high binding affinity (equilibrium dissociation constant 2 nM). The target epitope was identified at the N-terminal end, using experimental alanine scanning. Further, the mAb paratope was identified and characterized with hydrogen-deuterium-exchange, and a molecular model for the (Oslo-2 mAb:611-CTF-p95HER2) complex was generated by an experimental-information-driven docking approach. We conclude that the Oslo-2 mAb has a high affinity and is highly specific for 611-CTF-p95HER2. The Ab may be used to develop potent and safe therapies, overcoming p95HER2-mediated tumor escape, as well as for developing diagnostic assays.

Development of STEAP1 targeting chimeric antigen receptor for adoptive cell therapy against cancer

Chimeric antigen receptors (CARs) that retarget T cells against CD19 show clinical efficacy against B cell malignancies. Here, we describe the development of a CAR against the six-transmembrane epithelial antigen of prostate-1 (STEAP1), which is expressed in ∼90% of prostate cancers, and subgroups of other malignancies. STEAP1 is an attractive target, as it is associated with tumor invasiveness and progression and only expressed at low levels in normal tissues, apart from the non-vital prostate gland. We identified the antibody coding sequences from a hybridoma and designed a CAR that is efficiently expressed in primary T cells. The T cells acquired the desired anti-STEAP1 specificity, with a polyfunctional response including production of multiple cytokines, proliferation, and the killing of cancer cells. The response was observed for both CD4⁺ and CD8⁺ T cells, and against all STEAP1⁺ target cell lines tested. We evaluated the in vivo CAR T activity in both subcutaneous and metastatic xenograft mouse models of prostate cancer. Here, the CAR T cells infiltrated tumors and significantly inhibited tumor growth and extended survival in a STEAP1-dependent manner. We conclude that the STEAP1 CAR exhibits potent in vitro and in vivo functionality and can be further developed toward potential clinical use.

Improving public cancer care by implementing precision medicine in Norway: IMPRESS-Norway

Background

Matching treatment based on tumour molecular characteristics has revolutionized the treatment of some cancers and has given hope to many patients. Although personalized cancer care is an old concept, renewed attention has arisen due to recent advancements in cancer diagnostics including access to high-throughput sequencing of tumour tissue. Targeted therapies interfering with cancer specific pathways have been developed and approved for subgroups of patients. These drugs might just as well be efficient in other diagnostic subgroups, not investigated in pharma-led clinical studies, but their potential use on new indications is never explored due to limited number of patients.

Methods

In this national, investigator-initiated, prospective, open-label, non-randomized combined basket- and umbrella-trial, patients are enrolled in multiple parallel cohorts. Each cohort is defined by the patient’s tumour type, molecular profile of the tumour, and study drug. Treatment outcome in each cohort is monitored by using a Simon two-stage-like ‘admissible’ monitoring plan to identify evidence of clinical activity.

All drugs available in IMPRESS-Norway have regulatory approval and are funded by pharmaceutical companies. Molecular diagnostics are funded by the public health care system.

Discussion

Precision oncology means to stratify treatment based on specific patient characteristics and the molecular profile of the tumor. Use of targeted drugs is currently restricted to specific biomarker-defined subgroups of patients according to their market authorization. However, other cancer patients might also benefit of treatment with these drugs if the same biomarker is present. The emerging technologies in molecular diagnostics are now being implemented in Norway and it is publicly reimbursed, thus more cancer patients will have a more comprehensive genomic profiling of their tumour. Patients with actionable genomic alterations in their tumour may have the possibility to try precision cancer drugs through IMPRESS-Norway, if standard treatment is no longer an option, and the drugs are available in the study. This might benefit some patients. In addition, it is a good example of a public–private collaboration to establish a national infrastructure for precision oncology.

Trial registrations EudraCT: 2020-004414-35, registered 02/19/2021; ClinicalTrial.gov: NCT04817956, registered 03/26/2021.

Strategies for Improving the Efficacy of CAR T Cells in Solid Cancers

Simple Summary

Cell therapy with genetically retargeted T cells shows strong clinical efficacy against leukaemia and lymphoma. To make this therapy efficient against solid cancers, a series of hurdles must be addressed. This includes the need to enable the T cells to survive long term in patients and to overcome immunosuppressive mechanisms in the tumour. Further, it is essential to prevent tumour cells from escaping by losing the protein that is recognised by the infused cells. The present article provides an overview of the key strategies that are currently being investigated to overcome these hurdles. A series of approaches have been described in preclinical models, but these remain untested in patients. The further progress of the field will depend on evaluating more strategies in a proper clinical setting.

Abstract

Therapy with T cells equipped with chimeric antigen receptors (CARs) shows strong efficacy against leukaemia and lymphoma, but not yet against solid cancers. This has been attributed to insufficient T cell persistence, tumour heterogeneity and an immunosuppressive tumour microenvironment. The present article provides an overview of key strategies that are currently investigated to overcome these hurdles. Basic aspects of CAR design are revisited, relevant for tuning the stimulatory signal to the requirements of solid tumours. Novel approaches for enhancing T cell persistence are highlighted, based on epigenetic or post-translational modifications. Further, the article describes CAR T strategies that are being developed for overcoming tumour heterogeneity and the escape of cancer stem cells, as well as for countering prevalent mechanisms of immune suppression in solid cancers. In general, personalised medicine is faced with a lack of drugs matching the patient’s profile. The advances and flexibility of modern gene engineering may allow for the filling of some of these gaps with tailored CAR T approaches addressing mechanisms identified as important in the individual patient. At this point, however, CAR T cell therapy remains unproved in solid cancers. The further progress of the field will depend on bringing novel strategies into clinical evaluation, while maintaining safety.

Long-Term Outcomes of a Phase I Study With UV1, a Second Generation Telomerase Based Vaccine, in Patients With Advanced Non-Small Cell Lung Cancer

Human telomerase reverse transcriptase (hTERT) is a target antigen for cancer immunotherapy in patients with non-small cell lung cancer (NSCLC). We have tested a novel hTERT vaccine, UV1, designed to give high population coverage. UV1 is composed of three synthetic long peptides containing multiple epitopes identified by epitope spreading data from long-term survivors from previous hTERT vaccination trials. Eighteen non-HLA-typed patients with stage III/IV NSCLC with no evidence of progression after prior treatments, were enrolled in a phase I dose-escalation study of UV1 vaccination with GM-CSF as adjuvant, evaluating safety, immune response, and long-term clinical outcome. Treatment with UV1 was well tolerated with no serious adverse events observed. Seventeen patients were evaluable for tumor response; 15 patients had stable disease as best response. The median progression free survival (PFS) was 10.7 months, and the median overall survival (OS) was 28.2 months. The OS at 4 years was 39% (7/18). Five patients are alive (median survival 5.6 years), and none of these are known to have received checkpoint therapy after vaccination. UV1 induced specific T-cell responses in the majority (67%) of patients. Immune responses were dynamic and long lasting. Both immune response (IR) and OS were dose related. More patients in the highest UV1 dosage group (700 μg) developed IRs compared to the other groups, and the IRs were stronger and occurred earlier. Patients in this group had a 4-year OS of 83%. The safety and clinical outcome data favor 700 μg as the preferred UV1 dose in this patient population. These results provide a rationale for further clinical studies in NSCLC with UV1 vaccination in combination with immune checkpoint blockade.

Clinical Trial Registration

https://www.clinicaltrials.gov, identifier NCT0178909.

ICON: a randomized phase IIb study evaluating immunogenic chemotherapy combined with ipilimumab and nivolumab in patients with metastatic hormone receptor positive breast cancer

BACKGROUND

Immunotherapy with checkpoint inhibitors (CPI) targeting PD-1 or CTLA-4 has emerged as an important treatment modality for several cancer forms. In hormone receptor positive breast cancer (HR + BC), this therapeutic approach is largely unexplored. We have started a clinical trial, ICON (CA209-9FN), evaluating CPI combined with selected chemotherapy in patients with metastatic HR + BC. The tumor lymphocyte infiltration is predictive for the effect of chemotherapy in BC. In ICON, we use anthracycline, which are considered as "immunogenic" chemotherapy, and low-dose cyclophosphamide, which has been reported to counter immunosuppressive cells.

METHODS

ICON is a randomized exploratory phase IIb study evaluating the safety and efficacy of combining nivolumab (nivo; anti-PD-1) and ipilimumab (ipi; anti-CTLA-4) with chemotherapy in subjects with metastatic HR + BC. Primary objectives are aassessment of toxicity and progression-free survival. The trial will enrol 75 evaluable subjects, randomized 2:3 into two arms (A:B). Patients in Arm A receive only chemotherapy, i.e. pegylated liposomal doxorubicin (PLD 20 mg/m² intravenously every 2nd week) + cyclophosphamide (cyclo; 50 mg per day, first 2 weeks in each 4 week cycle). Patients in Arm B receive PLD + cyclo + ipilimumab (1 mg intravenously every 6th week) + nivolumab (240 mg intravenously every 2nd week). Patients in arm A will be offered ipi + nivo after disease progression.

DISCUSSION

ICON is among the first clinical trials combining chemotherapy with PD-1 and CTLA-4 blockade, and the first in BC. There is a strong preclinical rationale for exploring if anthracyclines, which are considered to induce immunogenic cell death, synergize with CPI, and for combining PD-1 and CTLA-4 blockade, as these checkpoints are important in different phases of the immune response. If the ICON trial suggests acceptable safety and provide a signal of clinical efficacy, further studies are warranted. The cross-over patients from Arm A receiving ipilimumab/nivolumab without concomitant chemotherapy represent the first BC cohort receiving this therapy. The ICON trial includes a series of translational sub-projects addressing clinically important knowledge gaps. These studies may uncover biomarkers or mechanisms of efficacy and resistance, thereby informing the development of novel combinatory regimes and of personalised biomarker-based therapy. Trial registration NCT03409198, Jan 24th 2018; https://clinicaltrials.gov/ct2/show/record/NCT03409198.

ALICE: a randomized placebo-controlled phase II study evaluating atezolizumab combined with immunogenic chemotherapy in patients with metastatic triple-negative breast cancer

BACKGROUND

Immunotherapy with checkpoint inhibitors (CI) represents an important novel development in cancer treatment. Metastatic triple-negative breast cancer (mTNBC) is incurable, with a median survival of only ~ 13 months. We have initiated the randomized placebo-controlled phase IIb study ALICE, evaluating PD-L1 blockade combined with immunogenic chemotherapy in mTNBC patients (n = 75). Intriguingly, the host immune response is strongly predictive for the effect of chemotherapy in mTNBC. In the ALICE trial, we release the brake on the immune response by use of atezolizumab, an inhibitory antibody against PD-L1. We utilize anthracyclines, shown to trigger the immune system, and low-dose cyclophosphamide, which has been reported to counter immunosuppressive cells.

METHODS

ALICE is a randomized, double-blind, placebo-controlled exploratory phase II study evaluating the safety and efficacy of atezolizumab when combined with immunogenic chemotherapy in subjects with mTNBC. The trial will enroll 75 evaluable subjects, randomized 2:3 into two arms (A:B). The patients receive identical chemotherapy, i.e. pegylated liposomal doxorubicin (PLD 20 mg/m² intravenously every 2nd week) + cyclophosphamide (50 mg per day, first 2 weeks in each 4 week cycle). Patients in arm A receive placebo, while patients in arm B receive atezolizumab. The primary objectives are assessment of toxicity and progression-free survival. The secondary objectives include overall survival, tumor response rate, clinical benefit rate, patient reported outcomes, biomarkers and assessment of tumor-immune evolution during therapy.

DISCUSSION

The question of how CI should be combined with chemotherapy, is a key challenge facing the field. There is a strong preclinical rationale for exploring if anthracyclines, which are considered to induce immunogenic cell death, synergize with PD-L1 blockade, and if low-dose cyclophosphamide counters tumor tolerance. However, the data from patients is as yet very limited, and the clinical evaluation of these hypotheses is among the key objectives in the ALICE trial. The study includes extensive biobanking and translational sub-projects, also addressing other clinically important questions. These analyses may uncover mechanisms of drug efficacy or tumor resistance, and identify biomarkers allowing personalized therapy. If the trial suggests acceptable safety of the ALICE therapy and provide a signal of clinical efficacy, further studies are warranted. Trial registration NCT03164993, May 24th 2017; https://clinicaltrials.gov/ct2/show/record/NCT03164993.

An independent poor-prognosis subtype of breast cancer defined by a distinct tumor immune microenvironment

How mixtures of immune cells associate with cancer cell phenotype and affect pathogenesis is still unclear. In 15 breast cancer gene expression datasets, we invariably identify three clusters of patients with gradual levels of immune infiltration. The intermediate immune infiltration cluster (Cluster B) is associated with a worse prognosis independently of known clinicopathological features. Furthermore, immune clusters are associated with response to neoadjuvant chemotherapy. In silico dissection of the immune contexture of the clusters identified Cluster A as immune cold, Cluster C as immune hot while Cluster B has a pro-tumorigenic immune infiltration. Through phenotypical analysis, we find epithelial mesenchymal transition and proliferation associated with the immune clusters and mutually exclusive in breast cancers. Here, we describe immune clusters which improve the prognostic accuracy of immune contexture in breast cancer. Our discovery of a novel independent prognostic factor in breast cancer highlights a correlation between tumor phenotype and immune contexture.

In breast cancer, the immune infiltration of the tumour associates with clinical outcome. Here, the authors infer immune context based on gene expression data and identify a new independent subtype linked to pro-tumorigenic immune infiltration.

Abstract 3190: Standardization and clinical implementation of liquid biopsy assays - IMI's CANCER-ID

The Innovative Medicines Initiative (IMI) project CANCER-ID (www.cancer-id.eu) is a 5 year (2015-2019) international public-private partnership of currently 40 partners from 14 countries with the aim to evaluate technologies for Circulating Tumor Cell (CTC), circulating free tumor DNA (ctDNA), microRNA (miRNA) and exosome enrichment, isolation and analysis. At the core of CANCER-ID’s activities are establishment of harmonized best practice protocols from patient sample collection, pre-analytical sample handling, sample and bioinformatics analyses down to the actionable information guiding patient selection and personalized treatment. CANCER-ID is furthermore testing and supporting development of standards for liquid biopsy as well as clinical implementation of liquid biopsy based protocols in the clinical setting. This includes interaction with regulatory bodies in Europe (EMA Innovation Task Force) and the US (FDA Public-Private Partnership liaison) to support future approval of liquid biopsies in multi-centered worldwide clinical studies.

During the clinical validation phase of the project, clinical-ready liquid biopsy protocols have been implemented in an observational study on the potential predictive value of monitoring treatment response towards Immune Checkpoint Inhibition (ICI) in 180 NSCLC patients at the UMC Groningen, The Netherlands, as well as in two ICI-chemotherapy combination studies in Triple-Negative Breast Cancer and Luminal B-type breast cancer, respectively, run by the University of Oslo, Norway (ALICE NCT03164993 and ICON NCT03409198). Within both studies, blood has been collected at baseline and at follow-up visits for ctDNA and CTC analysis, including technical evaluation of CTC PD-L1 protein expression. The aim is to assess whether the allelic frequency of mutations identified by plasma NGS as a potential measure for Tumor Mutational Burden or the number of PD-L1–positive/overall CTCs at different time points is indicative of treatment success. The studies aim at providing data to assess whether clinical predictive information could be inferred from baseline number of detected mutations and PD-L1 expressing CTCs. Preliminary data of these analyses will be presented.

As a follow-up activity of the IMI CANCER-ID program, the European Liquid Biopsy Society (ELBS) is currently being established by Prof. Pantel at UKE Hamburg, Germany. The ELBS will be open to all interested liquid biopsy stakeholders worldwide as a platform for scientific exchange, further efforts to standardize technologies and protocols in the field as well as for the initiation of new basic and clinical research projects with the aim to make liquid biopsies an integral part of clinical studies and patient care.

This work is supported by IMI JU & EFPIA (grant no. 115749, CANCER-ID). Samples from patients and healthy volunteers, respectively, were collected under signed informed consent.

Citation Format: Klaus Pantel, Leon W. Terstappen, Nicolò Manaresi, Harry J. Groen, Ed M. Schuuring, Ellen Heitzer, Michael Speicher, Bjørn Naume, Jon Amund Kyte, Thomas Schlange, for the IMI CANCER-ID consortium. Standardization and clinical implementation of liquid biopsy assays - IMI's CANCER-ID [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3190.

Transient redirection of T cells for adoptive cell therapy with telomerase-specific T helper cell receptors isolated from long term survivors after cancer vaccination

Adoptive cell therapy (ACT) with retargeted T cells has produced remarkable clinical responses against cancer, but also serious toxicity. Telomerase is overexpressed in most cancers, but also expressed in some normal cells, raising safety concerns. We hypothesize that ACT with T-helper cell receptors may overcome tumour tolerance, mobilize host immune cells and induce epitope spreading, with limited toxicity. From long term survivors after cancer vaccination, we have isolated telomerase-specific T cell receptors (TCRs) from T-helper cells. Herein, we report the development of transient retargeting of T cells with mRNA-based TCRs. This strategy allows for safer clinical testing and meaningful dose escalation. DP4 is the most common HLA molecule. We cloned two telomerase-specific, DP4-restricted TCRs into the mRNA expression vector pCIpA102, together with the sorter/marker/suicide gene RQR8. Donor T cells were electroporated with mRNA encoding TCR_RQR8. The results showed that both TCR_RQR8 constructs were expressed in >90% of T cells. The transfected T cells specifically recognized the relevant peptide, as well as naturally processed epitopes from a 177aa telomerase protein fragment, and remained functional for six days. A polyfunctional and Th1-like cytokine profile was observed. The TCRs were functional in both CD4+and CD8+recipient T cells, even though DP4-restricted. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired telomerase-specificity and functionality. Preclinical experiments may provide limited information on the efficacy and toxicity of T-helper TCRs, as these mobilize the host immune system. We therefore intend to use the mRNA-based TCRs for a first-in-man trial.

Noninvasive profiling of serum cytokines in breast cancer patients and clinicopathological characteristics

Cancers elicit an immune response by modifying the microenvironment. The immune system plays a pivotal role in cancer recognition and eradication. While the potential clinical value of infiltrating lymphocytes at the tumor site has been assessed in breast cancer, circulating cytokines – the molecules coordinating and fine-tuning immune response – are still poorly characterized.

Using two breast cancer cohorts (MicMa, n = 131, DCTB, n = 28) and the multiplex Luminex platform, we measured the levels of 27 cytokines in the serum of breast cancer patients prior to treatment. We investigated the cytokine levels in relation to clinicopathological characteristics and in perspective of the tumor infiltrating immune cells predicted from the bulk mRNA expression data.

Unsupervised clustering analysis of the serum cytokine levels in the MicMa cohort identified a cluster of pro-inflammatory, pro-angiogenic, and Th2-related cytokines which was associated with poor prognosis. Notably high levels of platelet derived growth factor BB (PDGF) reflected a more aggressive tumor phenotype and larger tumor size. A significant positive correlation between serum levels of interferon gamma-induced protein 10 (IP10) and its mRNA expression at the tumor site suggested that tumor-IP10-production may outflow to the bloodstream. High IP10 serum levels were associated with a worse prognosis. Finally, we found serum levels of both PDGF and IP10 associated with enrichment scores of specific tumor infiltrating immune cells.

Our study suggests that monitoring cytokine circulating levels in breast cancer could be used to characterize breast cancers and the immune composition of their microenvironment through readily available biological material.

Serum cytokine levels in breast cancer patients during neoadjuvant treatment with bevacizumab

A high concentration of circulating vascular endothelial growth factor (VEGF) in cancer patients is associated with an aggressive tumor phenotype. Here, serum levels of 27 cytokines and blood cell counts were assessed in breast cancer patients receiving neoadjuvant chemotherapy with or without bevacizumab (Bev) in a randomized cohort of 132 patients with non-metastatic HER2-negative tumors. Cytokine levels were determined prior to treatment and at various time-points. The cytotoxic chemotherapy regimen of fluorouracil, epirubicin, and cyclophosphamide (FEC) had a profound impact on both circulating white blood cells and circulating cytokine levels. At the end of FEC treatment, the global decrease in cytokine levels correlated with the drop in white blood cell counts and was significantly greater in the patients of the Bev arm for cytokines, such as VEGF-A, IL-12, IP-10 and IL-10. Among patients who received Bev, those with pathological complete response (pCR) exhibited significantly lower levels of VEGF-A, IFN-γ, TNF-α and IL-4 than patients without pCR. This effect was not observed in the chemotherapy-only arm. Certain circulating cytokine profiles were found to correlate with different immune cell types at the tumor site. For the Bev arm patients, the serum cytokine levels correlated with higher levels of cytotoxic T cells at the end of the therapy regimen, which was indicative of treatment response. The higher response rate for Bev-treated patients and stronger correlations between serum cytokine levels and infiltrating CD8T cells merits further investigation.

Abstract P2-05-16: Establishment of molecular profiling for individual treatment decisions in early breast cancer – Clinical impact of PAM50 and PAM50 risk of recurrence score after more than 16 years follow up

Background

Molecular profiling has recently been included in recommendations for decisions on adjuvant treatment in breast cancer (BrCa). However, the use of molecular profiling has not yet been widely established in all countries. Additional studies may give important information about the clinical relevance of the tests.

Aims

The study aims to discover the long term prognostic impact of PAM50 and PAM50 ROR score on survival for early BrCa pts according to treatment, with comparison to the routine clinical and histopathological parameters.

Patients and methods

Unselected early BrCa pts (n=651) from the Oslo Micromet project (n=920) having available FFPE primary tumor tissue were included in the current study. The pts were enrolled from 1995-1998. Follow up status is available for distant disease (median FU 7 years) and BrCa death (16.0-19.7 years after study inclusion). Clinical and histopathological parameters have been collected from the hospital records. FFPE tissue sections were macrodissected, RNA isolated from the dissected tumor tissue, followed by analysis of the PAM50 gene list on the Nanostring Platform. The samples were run in research mode and the raw data was sent to Nanostring (Seattle) for determination of the PAM50 subtype and ROR score.

Results

Of the 651 included pts, 323 did not receive any adjuvant systemic treatment (pT1pN0 patients), 161 tamoxifen only, the rest chemotherapy+/-tamoxifen. Twelve preoperatively treated pts were excluded from the analyses. Of the 639 remaining pts, PAM50 molecular profiling defined 52.3% as LumA, 26.8% LumB, 10.6% HER2enriched and 10.3% Basal. Multivariate analysis showed that the PAM50 intrinsic subtypes yielded prognostic information in addition to the established clinicopathological variables (pT, Grade, pN, age HR/HER2 subgroups, systemic treatment)(BCSS: HazardR vs LumA: 2.7 (95% CI 1.7-4.1) for LumB, 3.5 (1.8-6.8) for HER2enriched, 1.8 (0.8-4.2) for Basal). For the HR+HER2- pts, the risk classification by ROR score was an independent prognostic factor (BCSS: HazardR vs low risk: 3.1 (1.2-8.1) for intermediate, 6.6 (2.5-17.1) for high risk). In univariate analysis, the PAM50 intrinsic subtype classification separated clinical outcome both for all pts, for no adjuvant treated pts (both p<0.001, log rank), for the HR+HER2- (p<0.001), HR+HER2+ (p=0.061) and HR-HER2- (p=0.015) subgroups. Among the pT1-2pN0 HR+HER2- pts with no adjuvant treatment (n=222), risk classification by ROR score categorized 52.7% of the pts as low risk with excellent prognosis (BrCa death 4.2%), 29.7% as intermediate risk (BrCa death 16.7%) and 17.6% as high risk (BrCa death 35.9%)(p<001, log rank). For the pT1-2pN0-1 HR+HER2- pts who received adjuvant tamoxifen only (n=102), a low and similar risk of BrCa death was observed among the low and intermediate ROR risk groups. The high risk group had poor prognosis (BrCa death 32.7%)(p<0.001). Similar results were obtained for patients classified as LumA.

Conclusions

PAM50 subtype classification and ROR score improves classification of BrCa pts into prognostic groups, allowing more precise identification of future recurrence risk and improved basis for adjuvant treatment decisions.

Citation Format: Naume B, Borgen E, Falk RS, Ohnstad HO, Lien TG, Aaserud M, Sveli MAT, Kyte JA, Kristensen V, Geitvik G, Schlichting E, Wist E, Sørlie T, Russnes H. Establishment of molecular profiling for individual treatment decisions in early breast cancer – Clinical impact of PAM50 and PAM50 risk of recurrence score after more than 16 years follow up [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-16.

Cancer immunotherapy: from the lab to clinical applications-Potential impact on cancer centres' organisation

This report covers the Immunotherapy sessions of the 2016 Organisation of European Cancer Institutes (OECI) Oncology Days meeting, which was held on 15th–17th June 2016 in Brussels, Belgium. Immunotherapy is a potential cancer treatment that uses an individual’s immune system to fight the tumour. In recent years significant advances have been made in this field in the treatment of several advanced cancers. Cancer immunotherapies include monoclonal antibodies that are designed to attack a very specific part of the cancer cell and immune checkpoint inhibitors which are molecules that stimulate or block the inhibition of the immune system. Other cancer immunotherapies include vaccines and T cell infusions. This report will summarise some of the research that is going on in this field and will give us an update on where we are at present.

Non-small cell lung cancer is characterised by a distinct inflammatory signature in serum compared with chronic obstructive pulmonary disease

Development of lung cancer is closely related to smoking in a majority of patients. Most smokers, however, do not develop lung cancer in spite of a high mutational load accumulating in the lung tissue. Here we investigate whether a cancer-specific footprint can be revealed by investigating circulating inflammatory markers in patients with non-small cell lung cancer (NSCLC) compared with patients with chronic obstructive pulmonary disease (COPD), both cohorts characterised by similar smoking history. Serum concentrations of 57 cytokines and matrix metalloproteinases (MMPs) from 43 patients with advanced NSCLC were evaluated by multiplex immunoassays and compared with serum samples from 35 patients with COPD. Unsupervised hierarchical clustering and non-parametric analyses were performed. False discovery rate was used to adjust for multiple testing. Clustering of cytokine and MMP concentrations in the serum revealed a distinct separation of the NSCLC patients from the COPD group. Individual concentrations of thymus and activation-regulated cytokine (C-C motif chemokine ligand 17), Gro-b (C-X-C motif chemokine ligand 2 (CXCL2)), CXCL13, interleukin (IL)-1ra, IL-6, IL-8 (CXCL8), IL-16, IL-17A, macrophage migration inhibitory factor (MIF), granulocyte colony-stimulating factor, platelet-derived growth factor subunit B, MMP-2, MMP-8 and MMP-12 were significantly different in serum from NSCLC and COPD patients. Moreover, the interferon-γ/IL-10 ratio was lower in cancer patients compared with COPD patients, consistent with a cytokine milieu favouring tumour tolerance. Our results suggest that NSCLC is characterised by a distinct inflammatory signature in serum. The different cytokine profiles in NSCLC and COPD patients may represent tumour-promoting and tumour-suppressing immune responses developing in response to mucosal inflammation and mutations induced by smoking.

T-helper cell receptors from long-term survivors after telomerase cancer vaccination for use in adoptive cell therapy

We herein report retargeting of T-helper (Th) cells against the universal cancer antigen telomerase for use in adoptive cell therapy. The redirected Th cells may counter tumor tolerance, transform the inflammatory milieu, and induce epitope spreading and cancer senescence. We have previously conducted a series of trials evaluating vaccination with telomerase peptides. From long-term survivors, we isolated >100 CD4⁺ Th-cell clones recognizing telomerase epitopes. The clones were characterized with regard to HLA restriction, functional avidity, fine specificity, proliferative capacity, cytokine profile, and recognition of naturally processed epitopes. DP4 is the most prevalent HLA molecule worldwide. Two DP4-restricted T-cell clones with different functional avidity, C13 and D71, were selected for molecular T-cell receptor (TCR) cloning. Both clones showed a high proliferative capacity, recognition of naturally processed telomerase epitopes, and a polyfunctional and Th1-weighted cytokine profile. TCR C13 and D71 were cloned into the retroviral vector MP71 together with the compact and GMP-applicable marker/suicide gene RQR8. Both TCRs were expressed well in recipient T cells after PBMC transduction. The transduced T cells co-expressed RQR8 and acquired the desired telomerase specificity, with a polyfunctional response including production of TNFa, IFNγ, and CD107a. Interestingly, the DP4-restricted TCRs were expressed and functional both in CD4⁺ and CD8⁺ T cells. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired hTERT-specificity and functionality. We hypothesize that adoptive therapy with Th cells may offer a powerful novel approach for overcoming tumor tolerance and synergize with other forms of immunotherapy.

Immune response and long-term clinical outcome in advanced melanoma patients vaccinated with tumor-mRNA-transfected dendritic cells

The most effective anticancer immune responses are probably directed against patient-specific neoantigens. We have developed a melanoma vaccine targeting this individual mutanome based on dendritic cells (DCs) loaded with autologous tumor-mRNA. Here, we report a phase I/II trial evaluating toxicity, immune response and clinical outcome in 31 metastatic melanoma patients. The first cohort (n = 22) received the vaccine without any adjuvant; the next cohort (n = 9) received adjuvant IL2. Each subject received four weekly intranodal or intradermal injections, followed by optional monthly vaccines. Immune response was evaluated by delayed-type hypersensitivity (DTH), T cell proliferation and cytokine assays. Data were collected for 10 y after inclusion of the last patient. No serious adverse events were detected. In the intention-to-treat-cohort, we demonstrated significantly superior survival compared to matched controls from a benchmark meta-analysis (1 y survival 43% vs. 24%, 2 y 23% vs. 6.6%). A tumor-specific immune response was demonstrated in 16/31 patients. The response rate was higher after intradermal than intranodal vaccination (80% vs. 38%). Immune responders had improved survival compared to non-responders (median 14 mo vs. 6 mo; p = 0.030), and all eight patients surviving >20 mo were immune responders. In addition to the tumor-specific response, most patients developed a response against autologous DC antigens. The cytokine profile was polyfunctional and did not follow a Th1/Th2 dichotomy. We conclude that the favorable safety profile and evidence of a possible survival benefit warrant further studies of the RNA/DC vaccine. The vaccine appears insufficient as monotherapy, but there is a strong rationale for combination with checkpoint modulators.

Abstract B141: Combining the telomerase peptide cancer vaccine UV1 with CTLA-4 blockade in patients with metastatic malignant melanoma: Proof of principle and early clinical reports from a phase I/IIa trial

The purpose of this clinical phase I/IIa, open label, single arm, interventional study (EudraCT No 2013-005582-39) is to investigate the safety, clinical and immunological responses of a therapeutic telomerase peptide vaccine, UV1, combined with ipilimumab in patients with metastatic melanoma (MM).

The CTLA-4 antibody ipilimumab produces long term survival benefits in ca.20% of patients with MM. The mechanism of action of ipilimumab suggests that combinations with therapies inducing tumor-specific immune responses, such as vaccines, may lead to additive and even synergistic anti-tumor activity. We hypothesized that a telomerase peptide-based vaccine in combination with ipilimumab would improve therapeutic efficacy in patients with MM. Telomerase promotes elongation of telomeres after each cell division, representing the key enzymatic process in preventing telomere shortening. It is responsible for human cell immortalization and cancer pathogenesis, and is present in 85-90% of cancer tissues. Thus, telomerase-based immunotherapy has been investigated in several tumor types. Available blood samples from long term cancer survivors previously treated with different types of human telomerase reverse transcriptase subunit (hTERT) vaccines identified a new set of peptide epitopes. T cell responses to these peptides form spontaneously after vaccination by epitope spreading and are found only in patients with remarkable clinical courses, suggesting a role in tumor eradication. This led to the development of UV1, a therapeutic cancer vaccine consisting of a mixture of 3 synthetic peptides representing naturally occurring fragments of human hTERT. Ongoing phase I/IIa trials with UV1 in non-small-cell lung cancer and prostate cancer (EudraCT No 2012-001852-20 and 2012-002411-26, respectively) have shown potent, durable T cell responses against UV1 peptides and low toxicity (unpublished data).

In the present protocol, patients with a histologically or cytologically confirmed diagnosis of unresectable AJCC stage III/IV MM, ECOG 0-1 and an adequate renal, hepatic and hematological function are eligible. Any previous treatment is allowed. Patients with active brain metastases, a history of autoimmune disease, splenic surgery or irradiation, allogenic stem cell transplantation, known hypersensitivity to the investigational products, uncontrolled infectious disease, pregnant or breastfeeding, will be excluded. Intradermal UV1 vaccines of 300 mcg and 75 mcg GM-CSF are administered 7, 5, and 3 days before and 11 days after the first dose of ipilimumab, then 3 days before every dose of ipilimumab, and subsequently every 4th week until week 48 or treatment cessation. Ipilimumab 3 mg/kg is given IV every 3rd week for a total of 4 doses. Each patient will be followed up 5 weeks after the completion of the last study treatment. Adverse events are recorded in coherence with CTCAE vs. 4.0. Tumor response is evaluated according to RECIST vs.1.1. Immune responses against UV1 peptides are monitored by standard immunoassays. Potential predictive biomarkers will be explored in an extensive program involving sequential tumor biopsies, DNA sequencing and mRNA expression. The first patient was enrolled 16 January 2015, estimated completed recruitment by one year. 3 out of 20 patients have been recruited so far. Data from the first 3 patients until week 16 will be reported.

Citation Format: Elin Aamdal, Tormod Kyrre Guren, Else Marit Inderberg Suso, Gunnar Kvalheim, Jon Amund Kyte, Øyvind Kongstun Arnesen, Steinar Aamdal, Gustav Gaudernack. Combining the telomerase peptide cancer vaccine UV1 with CTLA-4 blockade in patients with metastatic malignant melanoma: Proof of principle and early clinical reports from a phase I/IIa trial. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B141.

Immunological factors influencing clinical outcome in lung cancer patients after telomerase peptide vaccination

We have previously reported two trials in non-small cell lung cancer (NSCLC) evaluating vaccine therapy with the telomerase peptide GV1001. The studies demonstrated considerable differences in survival among immune responders, highlighting that an immune response is not necessarily beneficial. In the present study, we conducted long-term clinical follow-up and investigated immunological factors hypothesized to influence clinical efficacy. Peripheral blood mononuclear cells from 33 NSCLC trial patients and 15 healthy donors were analyzed by flow cytometry for T regulatory cells (Tregs, CD4(+)CD25(+)CD127(low/-)FOXP3(+)) and two types of myeloid-derived suppressor cells (MDSCs, HLA-DR (low) CD14 (+) or Lin (-/lo) HLA-DR (-) CD33 (+) CD11b (+)). T cell cultures were analyzed for 17 cytokines. The results demonstrated that immune responders had increased overall survival (OS, p < 0.001) and progression-free survival (p = 0.003), compared to subjects without immunological response. The mean OS advantage was 54 versus 13 months. Six patients were still alive at the last clinical update, all belonging to the immune responders. No serious toxicity had developed (maximum observation 13 years). Most patients developed a polyfunctional cytokine profile, with high IFNγ/IL-4 and IFNγ/IL-10 ratios. Low Treg levels were associated with improved OS (p = 0.037) and a favorable cytokine profile, including higher IFNγ/IL-10 ratios. High CD33(+) MDSC levels were associated with poorer immune response rate (p = 0.005). The levels of CD14(+) MDSC were significantly higher in patients than in healthy controls (p = 0.012). We conclude that a randomized GV1001 trial in NSCLC is warranted. The findings suggest that Tregs and MDSCs are associated with a tolerogenic cytokine milieu and impaired clinical efficacy of vaccine responses.

Immune escape of cancer cells with beta2-microglobulin loss over the course of metastatic melanoma

Cancer cells escape T-cell-mediated destruction by losing human leukocyte antigen (HLA) class I expression via various mechanisms, including loss of beta2-microglobulin (β2m). Our study illustrates the immune escape of HLA class I-negative tumor cells and chronological sequence of appearance of tumor β2m gene mutation in successive lesions obtained from a patient with metastatic melanoma. We observed a gradual decrease in HLA expression in consecutive lesions with few HLA-negative nodules in the primary tumor and the emergence of a totally negative lesion at later stages of the disease. We detected loss of β2m in β2m-negative nests of the primary tumor caused by a combination of two alterations: (i) a mutation (G to T substitution) in codon 67 in exon 2 of β2m gene, producing a stop codon and (ii) loss of the second gene copy by loss of heterozygosity (LOH) in chromosome 15. The same β2m mutation was found in a homogeneously β2m-negative metastasis 10 months later and in a cell line established from a biopsy of a postvaccination lymph node. Microsatellite analysis revealed the presence of LOH in chromosomes 6 and 15 in tumor samples, showing an accumulation of chromosomal loss at specific short tandem repeats in successive metastases during disease progression. HLA loss correlated with decreased tumor CD8+ T-cell infiltration. Early incidence of β2m defects can cause an immune selection and expansion of highly aggressive melanoma clones with irreversible genetic defects causing total loss of HLA class I expression and should be taken into consideration as a therapeutic target in the development of cancer immunotherapy protocols.

Telomerase peptide vaccination in NSCLC: a phase II trial in stage III patients vaccinated after chemoradiotherapy and an 8-year update on a phase I/II trial

PURPOSE

We report two clinical trials in non-small cell lung cancer (NSCLC) patients evaluating immune response, toxicity, and clinical outcome after vaccination with the telomerase peptide GV1001: a phase II trial (CTN-2006) in patients vaccinated after chemoradiotherapy and an 8-year update on a previously reported phase I/II trial (CTN-2000).

EXPERIMENTAL DESIGN

CTN-2006: 23 inoperable stage III patients received radiotherapy (2 Gy × 30) and weekly docetaxel (20 mg/m(2)), followed by GV1001 vaccination. CTN-2000: 26 patients were vaccinated with two telomerase peptides (GV1001 and I540). The immune responses were evaluated by T-cell proliferation and cytokine assays.

RESULTS

CTN-2006 trial: a GV1001-specific immune response developed in 16/20 evaluable patients. Long-term immunomonitoring showed persisting responses in 13 subjects. Serious adverse events were not observed. Immune responders recorded a median PFS of 371 days, compared with 182 days for nonresponders (P = 0.20). CTN-2000 trial update: 13/24 evaluable subjects developed a GV1001 response. The immune responders achieved increased survival compared with nonresponders (median 19 months vs. 3.5 months; P < 0.001). Follow-up of four long-time survivors showed that they all harbored durable GV1001-specific T-cell memory responses and IFNγ(high)/IL-10(low)/IL-4(low) cytokine profiles. Two patients are free of disease after 108 and 93 months, respectively.

CONCLUSIONS

Vaccination with GV1001 is well tolerated, immunizes the majority of NSCLC patients and establishes durable T-cell memory. The considerable immune response rate and low toxicity in the phase II trial support the concept of combining chemoradiotherapy with vaccination. The survival advantage observed for immune responders warrants a randomized trial.

Telomerase peptide vaccination combined with temozolomide: a clinical trial in stage IV melanoma patients

PURPOSE

The study is a proof-of-principle trial evaluating toxicity, immune response, and clinical response in melanoma patients after combined therapy with temozolomide and the telomerase peptide vaccine GV1001. Our previous GV1001 trials showed immune responses in approximately 60% of lung or pancreatic cancer patients.

EXPERIMENTAL DESIGN

Twenty-five subjects with advanced stage IV melanoma (M1B or M1C) received concomitant temozolomide and GV1001. Temozolomide was administered 200 mg/m² orally for 5 days every fourth week, and GV1001 as eight injections over 11 weeks. Immune response was evaluated by delayed type hypersensitivity, T-cell proliferation, and cytokine assays. The immunologic responders continued monthly vaccination.

RESULTS

The treatment was well tolerated. A GV1001-specific immune response was shown in 18 of 23 evaluated subjects (78%). Patients developing long-term T-cell memory survived more than those rapidly losing their responses. The immune response exhibited several characteristics of possible clinical significance including high IFNγ/IL-10 ratios, polyfunctional cytokine profiles, and recognition of naturally processed antigens. Survival compared favorably with matched controls from a benchmark meta-analysis (1 year: 44% vs. 24%, 2 years: 16% vs. 6.6%). The clinical responses developed gradually over years, contrary to what is expected from chemotherapy. Five patients developed partial tumor regression and six more recorded stable disease. One patient has no remaining disease on fluorodeoxyglucose positron emission tomography scans after 5 years.

CONCLUSIONS

The immunologic response rate is considerable compared with previous GV1001 trials without concomitant chemotherapy, although low toxicity is retained. The results warrant further studies of GV1001/temozolomide treatment and support the general concept of combining cancer vaccination with chemotherapy.

Cancer vaccination with telomerase peptide GV1001

Telomerase is highly expressed in essentially all cancer forms, while the expression in normal tissues is restricted. Moreover, telomerase activity is considered indispensable for tumor immortalization and growth. Human telomerase reverse transcriptase (hTERT), the rate-limiting subunit of the telomerase complex, is therefore an attractive target for cancer vaccination. The present review provides an update on the development of GV1001, a peptide vaccine representing a 16-aa hTERT sequence. GV1001 binds multiple HLA class II molecules and harbors putative HLA class I epitopes. The peptide may therefore elicit combined CD4/CD8 T-cell responses, considered important to initiate tumor eradication and long-term memory. Phase I/II trials in advanced pancreatic and pulmonary cancer patients have demonstrated GV1001-specific T-cell responses in > 50% of subjects, without clinically important toxicity. The results indicate a correlation between development of GV1001-specific responses and prolonged survival. However, as in most cancer vaccine trials, a large proportion of immune responders experience no clinical benefit. Long-term survivors harbor durable GV1001-specific T-cell responses with high IFN-gamma/IL-10 ratios and polyfunctional cytokine patterns. Interestingly, the cytokine profiles do not follow a T(H)1/T(H)2 delineation. Here, the author discusses how immunomonitoring may be improved to discriminate between efficient and pointless immune responses, and which questions to address in the further development of GV1001.

Unconventional cytokine profiles and development of T cell memory in long-term survivors after cancer vaccination

Cancer vaccine trials frequently report on immunological responses, without any clinical benefit. This paradox may reflect the challenge of discriminating between effective and pointless immune responses and sparse knowledge on their long-term development. Here, we have analyzed T cell responses in long-term survivors after peptide vaccination. There were three main study aims: (1) to characterize the immune response in patients with a possible clinical benefit. (2) To analyze the long-term development of responses and effects of booster vaccination. (3) To investigate whether the Th1/Th2-delineation applies to cancer vaccine responses. T cell clones were generated from all nine patients studied. We find that surviving patients harbor durable tumor-specific responses against vaccine antigens from telomerase, RAS or TGFbeta receptor II. Analyses of consecutive samples suggest that booster vaccination is required to induce robust T cell memory. The responses exhibit several features of possible clinical advantage, including combined T-helper and cytotoxic functionality, recognition of naturally processed antigens and diverse HLA-restriction and fine-specificity. CD4(-)CD8(-) T cell clones display unconventional cytotoxicity and specifically kill tumor cells expressing mutated TGFbeta receptor II. Cytokine profiling on the long-term survivors demonstrates high IFN gamma/IL10-ratios, favoring immunity over tolerance, and secretion of multiple chemokines likely to mobilize the innate and adaptive immune system. Interestingly, these pro-inflammatory cytokine profiles do not follow a Th1/Th2-delineation. Most IFN gamma(high)/IL4(low)/IL10(low) cultures include high concentrations of hallmark Th2-cytokines IL-5 and IL-13. This does not reflect a mixture of Th1- and Th2-clones, but applies to 19/20 T cell clones confirmed to be monoclonal through TCR clonotype mapping. The present study identifies several factors that may promote clinical efficacy and suggests that cytokine profiling should not rely on the Th1/Th2-paradigm, but assess the overall inflammatory milieu and the balance between key cytokines.

T cell responses in melanoma patients after vaccination with tumor-mRNA transfected dendritic cells

We have developed an individualized melanoma vaccine based on autologous dendritic cells (DCs) transfected with autologous tumor-mRNA. The vaccine targets the unique spectrum of tumor antigens in each patient and may recruit multiple T cell clones. In a recent phase I/II trial, we demonstrated T cell responses against vaccine antigens in 9/19 patients evaluable by T cell assays. Here, we report a follow-up study that was conducted to characterize interesting T cell responses and to investigate the effects of long-term booster vaccination. Two patients were selected for continued vaccine therapy. The clinical follow-up suggested a favorable clinical development in both patients. The immunological data (T cell proliferation/IFNgamma ELISPOT/Bioplex cytokine assays) indicated sustained T cell responses and suggested an enhancing effect of booster vaccinations. Both CD4(+) and CD8(+) T cell responses were demonstrated. From post-vaccination samples, we generated 39 T cell clones that responded specifically to stimulation by mRNA-transfected DCs and 12 clones that responded to mock-transfected DCs. These data clearly indicate a two-component vaccine response, against transfected and non-transfected antigens. T cell receptor (TCR) clonotype mapping, performed on 11 tDC-specific clones, demonstrated that 10/11 clones had different TCRs. The results thus indicate a broad spectrum T cell response against antigens encoded by the transfected tumor-mRNA. We generally observed mixed Th1/Th2 cytokine profiles, even in T cell clones that were confirmed to be derived from a single cell. This finding suggests that cytokine patterns after cancer vaccination may be more complex than indicated by the classic Th1/Th2 dichotomy.

[Cancer vaccines]

Immunotherapy is in principle attractive, as it exploits the immune system's own method of recognizing and destroying tumours. Tumour cells express a number of mutated or over-expressed antigens, which make it possible for the immune system to distinguish between tumour cells and normal cells. Cancer vaccines use tumour-associated antigens to stimulate the patient's immune cells. In the clinical setting, individual differences between cancer patients is of vital importance, as the majority of tumour antigens may be unique to each individual. Genetic differences in patients' immune systems also suggest the need for individualised vaccines. This article gives a short introduction to the basic principles of tumour immunology and development of cancer vaccines. Clinical trials with emphasis on those with peptide and dendritic cell vaccines are presented, and the future development of cancer vaccines is discussed. A number of trials have shown tumour-specific immune responses and demonstrated that side-effects are generally not a problem. Limited documentation is available for the clinical effects. It is important to establish why some immune responses appear to give tumour regression while others are without clinical importance.

Phase I/II trial of melanoma therapy with dendritic cells transfected with autologous tumor-mRNA

We have developed an individualized melanoma vaccine based on transfection of autologous dendritic cells (DCs) with autologous tumor-mRNA. Dendritic cells loaded with complete tumor-mRNA may generate an immune response against a broad repertoire of antigens, including unique patient-specific antigens. The purpose of the present phase I/II trial was to evaluate the feasibility and safety of the vaccine, and the ability of the DCs to elicit T-cell responses in melanoma patients. Further, we compared intradermal (i.d.) and intranodal (i.n.) vaccine administration. Twenty-two patients with advanced malignant melanoma were included, each receiving four weekly vaccines. Monocyte-derived DCs were transfected with tumor-mRNA by electroporation, matured and cryopreserved. We obtained successful vaccine production for all patients elected. No serious adverse effects were observed. A vaccine-specific immune response was demonstrated in 9/19 patients evaluable by T-cell assays (T-cell proliferation/interferon-gamma ELISPOT) and in 8/18 patients evaluable by delayed-type hypersensitivity (DTH) reaction. The response was demonstrated in 7/10 patients vaccinated intradermally and in 3/12 patients vaccinated intranodally. We conclude that immuno-gene-therapy with the described DC-vaccine is feasible and safe, and that the vaccine can elicit in vivo T-cell responses against antigens encoded by the transfected tumor-mRNA. The response rates do not suggest an advantage in applying i.n. vaccination.

Immunotherapy with allotumour mRNA-transfected dendritic cells in androgen-resistant prostate cancer patients

Here, we present results from a clinical trial employing a new vaccination method using dendritic cells (DCs) transfected with mRNA from allogeneic prostate cancer cell lines (DU145, LNCaP and PC-3). In all, 20 patients were enrolled and 19 have completed vaccination. Each patient received at least four weekly injections with 2 × 10⁷ transfected DCs either intranodally or intradermally. Safety and feasibility of vaccination were determined. Immune responses were measured as delayed-type hypersensitivity and by in vitro immunoassays including ELISPOT and T-cell proliferation in pre- and postvaccination peripheral blood samples. Serum prostate-specific antigen (PSA) levels and bone scans were monitored. No toxicity or serious adverse events related to vaccinations were observed. A total of 12 patients developed a specific immune response to tumour mRNA-transfected DCs. In total, 13 patients showed a decrease in log slope PSA. This effect was strengthened by booster vaccinations. Clinical outcome was significantly related to immune responses (n=19, P=0.002, r=0.68). Vaccination with mRNA-transfected DCs is safe and results in cellular immune responses specific for antigens encoded by mRNA derived from the prostate cancer cell lines. The observation that in some patients vaccination affected the PSA level suggests that this approach may become useful as a treatment modality for prostate cancer patients.

Resting small B cells present endogenous immunoglobulin variable-region determinants to idiotope-specific CD4(+) T cells in vivo

Antigenic determinants localized within the highly diversified V-regions of Ig are called idiotopes (Id). Processed Id-peptides can be presented on MHC class II molecules to CD4(+) T cells. If B cells present their endogenous Id-peptides, T cell activation could occur in the absence of nominal antigen, a potentially important process in T-B cooperation and immune regulation. To test this idea, we used mice made transgenic for a lambda2 L-chain (Id(+) mice). Another transgenic mouse strain expresses TCR transgenes with specificity for the Id (lambda2), presented on MHC class II molecules. When highly purified sorted Id(+) B cells and Id-specific T cells were sequentially injected into MHC syngeneic SCID host, T cell became blastoid, CD69(+) and proliferated. To exclude any role of host APC, MHC incompatible Rag2(- / -) mice (H-2(b)) were used as recipients for the Id(+) B and Id-specific T cells, with similar results. Exposure to extracellular Id(+) immunoglobulin (Ig) was not sufficient for Id priming of B cells in vivo, highlighting the preferential presentation of Id peptides derived from endogenous Ig, by B cells. The results suggest that B cells presenting Id self-peptides generated by V(D)J recombinations or somatic mutations may directly stimulate T cell in vivo in the absence of conventional antigen.