Plasma Proteome-Based Test for First-Line Treatment Selection in Metastatic Non-Small Cell Lung Cancer

PURPOSE

Current guidelines for the management of metastatic non-small cell lung cancer (NSCLC) without driver mutations recommend checkpoint immunotherapy with PD-1/PD-L1 inhibitors, either alone or in combination with chemotherapy. This approach fails to account for individual patient variability and host immune factors and often results in less-than-ideal outcomes. To address the limitations of the current guidelines, we developed and subsequently blindly validated a machine learning algorithm using pretreatment plasma proteomic profiles for personalized treatment decisions.

PATIENTS AND METHODS

We conducted a multicenter observational trial (ClinicalTrials.gov identifier: NCT04056247) of patients undergoing PD-1/PD-L1 inhibitor-based therapy (n = 540) and an additional patient cohort receiving chemotherapy (n = 85) who consented to pretreatment plasma and clinical data collection. Plasma proteome profiling was performed using SomaScan Assay v4.1.

RESULTS

Our test demonstrates a strong association between model output and clinical benefit (CB) from PD-1/PD-L1 inhibitor-based treatments, evidenced by high concordance between predicted and observed CB (R2 = 0.98, P < .001). The test categorizes patients as either PROphet-positive or PROphet-negative and further stratifies patient outcomes beyond PD-L1 expression levels. The test successfully differentiates between PROphet-negative patients exhibiting high tumor PD-L1 levels (≥50%) who have enhanced overall survival when treated with a combination of immunotherapy and chemotherapy compared with immunotherapy alone (hazard ratio [HR], 0.23 [95% CI, 0.1 to 0.51], P = .0003). By contrast, PROphet-positive patients show comparable outcomes when treated with immunotherapy alone or in combination with chemotherapy (HR, 0.78 [95% CI, 0.42 to 1.44], P = .424).

CONCLUSION

Plasma proteome-based testing of individual patients, in combination with standard PD-L1 testing, distinguishes patient subsets with distinct differences in outcomes from PD-1/PD-L1 inhibitor-based therapies. These data suggest that this approach can improve the precision of first-line treatment for metastatic NSCLC.

Biological insights from plasma proteomics of non-small cell lung cancer patients treated with immunotherapy

Introduction

Immune checkpoint inhibitors have made a paradigm shift in the treatment of non-small cell lung cancer (NSCLC). However, clinical response varies widely and robust predictive biomarkers for patient stratification are lacking. Here, we characterize early on-treatment proteomic changes in blood plasma to gain a better understanding of treatment response and resistance.

Methods

Pre-treatment (T0) and on-treatment (T1) plasma samples were collected from 225 NSCLC patients receiving PD-1/PD-L1 inhibitor-based regimens. Plasma was profiled using aptamer-based technology to quantify approximately 7000 plasma proteins per sample. Proteins displaying significant fold changes (T1:T0) were analyzed further to identify associations with clinical outcomes using clinical benefit and overall survival as endpoints. Bioinformatic analyses of upregulated proteins were performed to determine potential cell origins and enriched biological processes.

Results

The levels of 142 proteins were significantly increased in the plasma of NSCLC patients following ICI-based treatments. Soluble PD-1 exhibited the highest increase, with a positive correlation to tumor PD-L1 status, and, in the ICI monotherapy dataset, an association with improved overall survival. Bioinformatic analysis of the ICI monotherapy dataset revealed a set of 30 upregulated proteins that formed a single, highly interconnected network, including CD8A connected to ten other proteins, suggestive of T cell activation during ICI treatment. Notably, the T cell-related network was detected regardless of clinical benefit. Lastly, circulating proteins of alveolar origin were identified as potential biomarkers of limited clinical benefit, possibly due to a link with cellular stress and lung damage.

Conclusions

Our study provides insights into the biological processes activated during ICI-based therapy, highlighting the potential of plasma proteomics to identify mechanisms of therapy resistance and biomarkers for outcome.

Interferon-stimulated neutrophils as a predictor of immunotherapy response

Despite the remarkable success of anti-cancer immunotherapy, its effectiveness remains confined to a subset of patients-emphasizing the importance of predictive biomarkers in clinical decision-making and further mechanistic understanding of treatment response. Current biomarkers, however, lack the power required to accurately stratify patients. Here, we identify interferon-stimulated, Ly6Ehi neutrophils as a blood-borne biomarker of anti-PD1 response in mice at baseline. Ly6Ehi neutrophils are induced by tumor-intrinsic activation of the STING (stimulator of interferon genes) signaling pathway and possess the ability to directly sensitize otherwise non-responsive tumors to anti-PD1 therapy, in part through IL12b-dependent activation of cytotoxic T cells. By translating our pre-clinical findings to a cohort of patients with non-small cell lung cancer and melanoma (n = 109), and to public data (n = 1440), we demonstrate the ability of Ly6Ehi neutrophils to predict immunotherapy response in humans with high accuracy (average AUC ≈ 0.9). Overall, our study identifies a functionally active biomarker for use in both mice and humans.

Tumor-infiltrating lymphocyte transfusion in a patient with treatment refractory triple negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive form of breast cancer that is treated with chemotherapy. Recently, programmed death 1 (PD1) inhibition, as well as antibody-drug conjugates, have been added to the available treatment regimen, yet metastatic disease is fatal. Adoptive cell therapy (ACT) using tumor infiltrating lymphocytes (TILs) has been well described in melanoma, but less data is available on other solid malignancies.

CASE

Herein, we present a case of a 31-year-old patient diagnosed with Breast Cancer gene 1 (BRCA1) positive, TNBC. The patient's disease rapidly progressed while under standard treatment protocols. As a result, additional genetic testing of the tumor was carried out and revealed loss of BRCA1 heterozygosity, a double Tumor Protein 53 (TP53) mutation, and MYC amplification. Due to resistance to conventional therapy, an experimental approach was attempted using tumor-infiltrating lymphocytes in November 2021 at Hadassah University Medical Center. While receiving this treatment, the patient exhibited a reported subjective clinical improvement including a month spent out of the hospital. However, the final result, presumably due to Interleukin 2 (IL-2) toxicity, was the patient's passing.

CONCLUSION

This case is unique and peculiar regarding the treatment modality chosen, due to the extremely refractory disease the patient suffered from. After standard therapies rapidly failed, adoptive cell therapy was attempted with the infusion of TILs. This treatment has been shown effective in melanoma, however, there is an extreme paucity of data on other solid tumors, including TNBC. Although the patient ultimately demised presumably due to treatment side effects, brief clinical benefit was apparent. Further studies are warranted.

The future of affordable cancer immunotherapy

The treatment of cancer was revolutionized within the last two decades by utilizing the mechanism of the immune system against malignant tissue in so-called cancer immunotherapy. Two main developments boosted cancer immunotherapy: 1) the use of checkpoint inhibitors, which are characterized by a relatively high response rate mainly in solid tumors; however, at the cost of serious side effects, and 2) the use of chimeric antigen receptor (CAR)-T cells, which were shown to be very efficient in the treatment of hematologic malignancies, but failed to show high clinical effectiveness in solid tumors until now. In addition, active immunization against individual tumors is emerging, and the first products have reached clinical approval. These new treatment options are very cost-intensive and are not financially compensated by health insurance in many countries. Hence, strategies must be developed to make cancer immunotherapy affordable and to improve the cost-benefit ratio. In this review, we discuss the following strategies: 1) to leverage the antigenicity of "cold tumors" with affordable reagents, 2) to use microbiome-based products as markers or therapeutics, 3) to apply measures that make adoptive cell therapy (ACT) cheaper, e.g., the use of off-the-shelf products, 4) to use immunotherapies that offer cheaper platforms, such as RNA- or peptide-based vaccines and vaccines that use shared or common antigens instead of highly personal antigens, 5) to use a small set of predictive biomarkers instead of the "sequence everything" approach, and 6) to explore affordable immunohistochemistry markers that may direct individual therapies.

Seven-Year Follow-Up of the Phase III KEYNOTE-006 Study: Pembrolizumab Versus Ipilimumab in Advanced Melanoma

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Immune checkpoint inhibitors have led to unprecedented prolongation of overall survival (OS) for patients with advanced melanoma. Five-year follow-up of KEYNOTE-006 showed pembrolizumab prolonged survival versus ipilimumab. Efficacy results with 7-year follow-up are presented. At data cutoff (April 19, 2021), median follow-up was 85.3 months (range, 0.03-90.8 months). Median OS was 32.7 months for pembrolizumab versus 15.9 months for ipilimumab (hazard ratio [HR], 0.70; 95% CI, 0.58 to 0.83); 7-year OS was 37.8% and 25.3%, respectively. OS HRs favored pembrolizumab regardless of BRAF status or prior BRAF/MEK-inhibitor treatment and prognostic characteristics (elevated lactate dehydrogenase, large tumor size, and brain metastasis). Median modified progression-free survival (mPFS) was 9.4 months for pembrolizumab versus 3.8 months for ipilimumab; 7-year mPFS was 23.8% and 13.3%, respectively. In patients who completed ≥94 weeks of pembrolizumab, the 5-year OS was 92.9% and the 5-year mPFS was 70.1%. The objective response rate with second-course pembrolizumab (n = 16) was 56% (95% CI, 30 to 80) and the 2-year mPFS was 62.5%. These findings confirm that pembrolizumab provides long-term survival benefit in advanced melanoma.

Dupilumab for cancer-associated refractory pruritus

Background

Pruritus can be an intolerable symptom in patients with cancer. Type 2 inflammation, and specifically, the cytokines IL-4, IL-13, and IL-31, play major roles in the itching process. Dupilumab is an antibody against IL-4Rα, which is a common IL-4 and IL-13 receptor subunit. Blocking IL-4 and IL-13 activity reduces the synthesis of IL-31, the "itch cytokine," and receptors for these 3 cytokines are expressed on itch nerves. Dupilumab is approved for treating moderate-to-severe atopic dermatitis, of which itching is a significant symptom.

Objective

The objective of this case study was to present the initial evidence of the safety and efficacy of dupilumab as a treatment for intractable malignancy-associated pruritus in 3 patients, thereby providing a basis for further investigation in a larger cohort.

Methods

As a proof of concept, we used dupilumab in our center to treat 3 patients with intractable malignancy-associated pruritus. The first patient was a 73-year-old male with a history of prostate cancer, the second patient was a 75-year-old female with cutaneous T-cell lymphoma, and the third patient was a 32-year-old male with metastatic melanoma. All 3 patients experienced debilitating itching, which started at some stage after the malignancy had been diagnosed. Moreover, none of the 3 patients showed clinical evidence of atopic dermatitis or other causes of itching (eg, uremia or liver failure), and none of the 3 patients responded to conventional treatments for pruritus.

Results

Biweekly treatment with dupilumab led to an immediate improvement in itching, which subsided entirely after a few doses without any significant adverse effects.

Conclusion

We propose that dupilumab is a safe and effective treatment for intractable malignancy-associated pruritus, and we are currently testing it in a large cohort.

Preventing skin toxicities induced by EGFR inhibitors by topically blocking drug-receptor interactions

Epidermal growth factor receptor (EGFR) inhibitors are used to treat many advanced-stage epithelial cancers but induce severe skin toxicities in most treated patients. These side effects lead to a deterioration in the quality of life of the patients and compromise the anticancer treatment. Current treatment strategies for these skin toxicities focus on symptom reduction rather than preventing the initial trigger that causes the toxicity. In this study, we developed a compound and method for treating "on-target" skin toxicity by blocking the drug at the site of toxicity without reducing the systemic dose reaching the tumor. We first screened for small molecules that effectively blocked the binding of anti-EGFR monoclonal antibodies to EGFR and identified a potential candidate, SDT-011. In silico docking predicted that SDT-011 interacted with the same residues on EGFR found to be important for the binding of EGFR inhibitors cetuximab and panitumumab. Binding of SDT-011 to EGFR reduced the binding affinity of cetuximab to EGFR and could reactivate EGFR signaling in keratinocyte cell lines, ex vivo cetuximab-treated whole human skin, and A431-injected mice. Specific small molecules were topically applied and were delivered via a slow-release system derived from biodegradable nanoparticles that penetrate the hair follicles and sebaceous glands, within which EGFR is highly expressed. Our approach has the potential to reduce skin toxicity caused by EGFR inhibitors.

Abstract 2159: A pretreatment blood-based proteomic biomarker for enhanced decision-making in non-small cell lung cancer

Introduction: Treatment modality selection for metastatic NSCLC patients (immunotherapy alone vs. combination of immunotherapy with chemotherapy) relies mainly on determining the programmed cell death 1 (PD-L1) expression levels in the tumor. However, available assays are only moderately predictive. Here we set to develop PROphet®, a plasma proteomics-based predictive model for informing treatment decisions for NSCLC patients receiving immune checkpoint inhibitor (ICI)-based therapy.

Methods: Pre-ICI plasma samples were collected in 12 centers in a clinical trial (NCT04056247) from 367 advanced-stage NSCLC patients. Clinical benefit (CB) was assessed at 12 months based on the occurrence of progression-free survival (PFS) until this time point. Deep proteomic profiling of the plasma samples was performed using aptamer-based technology. A novel machine learning model was developed to determine the CB probability for each patient, and the performance was successfully evaluated on an independent validation set, followed by training and prediction over the entire cohort using cross-validation. The resulting PROphet® score (positive or negative) was determined by setting the median CB rate probability as a threshold. The patients were divided into four subgroups based on their PD-L1 expression level combined with their PROphet® score prediction, and the overall survival (OS) was examined for each subgroup.

Results: The PROphet® computational model was evaluated in a blinded manner on a subset of 85 patients and displayed strong predictive capability with area under the curve (AUC) of the receiver operating characteristics (ROC) plot of 0.78 (p-value = 5.00e-05), outperforming a PD-L1-based predictive model (AUC = 0.62; p-value 2.76e-01). When combining PROphet® score with PD-L1 expression levels, four different outcome patterns were identified: (i) Patients with PD-L1 ≥50% and PROphet® negative score, who displayed significantly longer OS when treated with ICI-chemotherapy combination therapy compared to ICI monotherapy and may consider combination therapy. (ii) Patients with PD-L1 ≥50% and PROphet® positive score, who benefit similarly from either treatment modalities, and may consider monotherapy to avoid the potential toxicity of the combination therapy. (iii) Patients with PD-L1&lt;50% and PROphet® negative score, who do not benefit from either treatment modalities and may consider chemotherapy alone or treatment beyond standard of care. (iv) Patients with PD-L1&lt;50% and PROphet® positive score who benefit from combination therapy.

Conclusions: Altogether, the PROphet® model, when combined with PD-L1 test, stratifies the patients into four subgroups, providing additional resolution to the PD-L1 biomarker currently used to guide treatment selection. Furthermore, the model accurately predicts CB at 12 months based on proteomic analysis of a pre-treatment plasma sample.

Citation Format: Michal Harel, Petros Christopoulos, Coren Lahav, Itamar Sela, Nili Dahan, Niels Reinmuth, Ina Koch, Alona Zer, Mor Moskovitz, Adva Levy-Barda, Michal Lotem, Hovav Nechushtan, Rivka Katzenelson, Abed Agbarya, Mahmoud Abu-Amna, Maya Gottfried, Ido Wolf, Ella Tepper, Yanyan Lou, Raya Leibowitz, Adam P. Dicker, David Gandara, David P. Carbone. A pretreatment blood-based proteomic biomarker for enhanced decision-making in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2159.

Dermatological adverse events under programmed cell death-1 inhibitors as a prognostic marker in metastatic melanoma

Melanoma is widely treated with programmed cell death-1 (PD-1) inhibitors. As part of their anti-tumor immunity effect, they increase the susceptibility to cutaneous immune-related adverse events (cIRAE) among other autoimmune effects. To characterize the manifestations of cIRAE in melanoma patients treated with PD-1 inhibitors, and evaluate the correlation with tumor response. A retrospective study of 95 metastatic malignant melanoma patients treated with PD-1 inhibitors at the Hadassah Medical Center during 2013-2016. The most common cIRAE was pruritus reported by 39 (41%) patients. All other cIRAE were noted in 34 patients (35.8%), of which the most common cutaneous manifestation was vitiligo, demonstrated in 17 patients (17.9%) followed by various rashes (7.4%, including erythema multiforme, oral lichen planus, photosensitive rash, insect bite-like reaction, and urticaria), psoriasiform rash (3.2%), bullous pemphigoid (3.2%), and eczema (1%). Interestingly, higher response rates to immunotherapy were demonstrated in patients who developed pruritus (85%) and cIRAE (88%), with lower mortality rates in the cIRAE group (38.2%) versus the non-cIRAE group (70.5%, p = 0.002). cIRAE are common among malignant melanoma patients treated with PD-1 inhibitors and may be a marker for favorable prognosis.

A distinct pattern of growth and RAC1 signaling in melanoma brain metastasis cells

BACKGROUND

Melanoma, the deadliest of skin cancers, has a high propensity to form brain metastases that are associated with a markedly worsened prognosis. In spite of recent therapeutic advances, melanoma brain lesions remain a clinical challenge, biomarkers predicting brain dissemination are not clear and differences with other metastatic sites are poorly understood.

METHODS

We examined a genetically diverse panel of human-derived melanoma brain metastasis (MBM) and extracranial cell lines using targeted sequencing, a Reverse Phase Protein Array, protein expression analyses, and functional studies in vitro and in vivo.

RESULTS

Brain-specific genetic alterations were not detected; however, MBM cells in vitro displayed lower proliferation rates and MBM-specific protein expression patterns associated with proliferation, DNA damage, adhesion, and migration. MBM lines displayed higher levels of RAC1 expression, involving a distinct RAC1-PAK1-JNK1 signaling network. RAC1 knockdown or treatment with small molecule inhibitors contributed to a less aggressive MBM phenotype in vitro, while RAC1 knockdown in vivo led to reduced tumor volumes and delayed tumor appearance. Proliferation, adhesion, and migration were higher in MBM vs. non-MBM lines in the presence of insulin or brain-derived factors and were affected by RAC1 levels.

CONCLUSIONS

Our findings indicate that despite their genetic variability, MBM engage specific molecular processes such as RAC1 signaling to adapt to the brain microenvironment and this can be used for the molecular characterization and treatment of brain metastases.

The role of immune checkpoint receptors in the malignant phenotype of cutaneous T cell lymphoma

Immune checkpoint receptors (ICR) modulate the immune response and are critical hubs for immunotherapy. However, data on their role in T lymphoid malignancies, such as cutaneous T cell lymphoma (CTCL), is sparse. We aimed to explore the role of ICR in the malignant features of transformed T lymphocytes and evaluate the effect of ICR-targeting monoclonal antibodies, often used as immunotherapy for solid tumors. We used the CTCL cell line HH and the Sézary cell line Hut78 to examine ICR expression and the effects of ICR inhibition on cell viability and proliferation. Despite their shared T cell progeny, the different CTCL cell lines exhibit markedly different ICR expression profiles. Programmed cell death-ligand 1 (PD-L1) was expressed by both cell lines, while programmed death-1 (PD-1) was expressed only by the HH cell line. Common to all malignant T cells was an autonomous hyper-proliferative state that did not require T cell receptor stimulation. A monoclonal antibody blocking PD-1 had a small but statistically significant augmenting effect on T cell proliferation. Of note, when the cells were exposed to ionizing radiation, healthy lymphocytes and those derived from the HH cell line were salvaged by anti-PD-L1. We show a regulatory role of ICR, mainly PD-1 and its ligand PD-L1, on cutaneous T cell malignancy.

Abstract CT557: Phase 1/2 study of quavonlimab (Qmab) + pembrolizumab (pembro) in patients (pts) with advanced melanoma that progressed on a PD-1/PD-L1 inhibitor

Background: Safe, effective treatment options for advanced melanoma that progressed on a PD-1/PD-L1 inhibitor is an unmet medical need. Results of the phase 1b KEYNOTE-029 trial showed promising antitumor activity in advanced melanoma with pembro combined with a CTLA-4 inhibitor. This ongoing, open-label, multiarm phase 1/2 study (NCT03179436) evaluating the CTLA-4 inhibitor Qmab + pembro showed antitumor activity as first-line treatment for advanced NSCLC and for previously treated extensive-stage SCLC. Data from the efficacy expansion phase in pts with advanced melanoma that progressed on a PD-1/PD-L1 inhibitor are presented.

Methods: Pts with unresectable stage III-IV melanoma and confirmed progressive disease (PD) per iRECIST within 12 wk of the last dose of a PD-1/PD-L1 inhibitor given alone or in combination for ≥2 doses (combinations with CTLA-4 inhibitors were not allowed) were randomly assigned (1:1) to receive Qmab 25 mg IV Q6W with or without pembro 400 mg IV Q6W; 100 pts in the Qmab + pembro arm and 40 pts in the Qmab monotherapy arm were planned for enrollment. Treatment in both arms was given for up to 18 cycles (~2 y) or until PD, toxicity, or pt withdrawal. Pts who had PD after ≥2 Qmab monotherapy cycles could crossover to Qmab + pembro. Tumor imaging was assessed Q9W to wk 54 and Q12W thereafter. Primary end points were safety and ORR by BICR per RECIST v1.1. Secondary and exploratory end points included DOR and PFS by BICR per RECIST v1.1 and OS.

Results: 151 pts were enrolled (n = 111, Qmab + pembro; n = 40, Qmab monotherapy); median time from first dose to database cutoff was 7.7 mo. In all pts, median age was 64 y; 66% of pts were male, 33% had BRAF-mutant tumors, and 50% had elevated LDH. Treatment-related adverse events (TRAEs) were reported in 87 pts (78%) in the Qmab + pembro arm and 24 pts (60%) in the Qmab monotherapy arm; grade 3/4 TRAEs were reported in 16 pts (14%) and 3 pts (8%), respectively. The most common TRAEs were pruritus (26%), fatigue (14%), diarrhea (14%), and rash (13%). No treatment-related deaths occurred in either arm; 5% of pts discontinued because of TRAEs. Confirmed ORR was 9% (95% CI, 4.4-15.9) with Qmab + pembro (1 CR, 9 PRs) and 3% (95% CI, 0.1-13.2) with Qmab monotherapy (1 PR). Median DOR was not reached (NR; range, 2.0+ to 13.8+ mo) with Qmab + pembro. DOR was 1.9+ with Qmab monotherapy. Median PFS was 2.1 mo (95% CI, 2.1-3.2) with Qmab + pembro and 2.1 mo (95% CI, 2.1-2.5) with Qmab monotherapy; 6-mo PFS rates were 21% and 13%, respectively. Median OS was NR (95% CI, 11.2 mo to NR) with Qmab + pembro and 7.8 mo (95% CI, 6.3 to NR) with Qmab monotherapy; 6-mo OS rates were 74% and 73%, respectively.

Conclusions: Qmab + pembro was generally well tolerated and provided modest antitumor activity in pts with advanced melanoma that progressed on a PD-1/PD-L1 inhibitor. This combination and a coformulation of Qmab + pembro will be further investigated in the KEYMAKER-U02 study.

Citation Format: Sanjeev Deva, Jacek Mackiewicz, Stephane Dalle, Helen Gogas, Iwona Lugowska, Alfonso Berrocal, Alexander M. Menzies, Michele Maio, Adnan Nagrial, Karmele Mujika Eizmendi, Jean-Jacques Grob, Christian Caglevic, Megan Lyle, Juan Martin-Liberal, Rachel Altura, Yixin Ren, Anuradha Khilnani, Jobin Cyrus, Shabana Siddiqi, Michal Lotem. Phase 1/2 study of quavonlimab (Qmab) + pembrolizumab (pembro) in patients (pts) with advanced melanoma that progressed on a PD-1/PD-L1 inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT557.

Personalized approach for response prediction and treatment management for non-small cell lung cancer patients based on a liquid biopsy

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Background: To date, predicting response to immune checkpoint blockade (ICB) therapy in non-small cell lung cancer (NSCLC) patients is based on assessing PD-L1 levels in tumor biopsies. However, such assays are only moderately predictive. In addition, the assays require a tumor biopsy and do not aid in identifying patient-specific resistance mechanisms beyond PD-L1. To overcome these issues, we developed a novel computational approach for predicting response to ICB based on pre-treatment proteomic measurements in liquid biopsies. Methods: Plasma samples were collected from 184 NSCLC patients prior to treatment, along with comprehensive clinical data, as part of an ongoing multi-center clinical trial (PROPHETIC; NCT04056247). Overall response rate (ORR) was assessed 3- and 6-months following treatment initiation. A deep proteomic profiling of each plasma sample was performed, measuring the expression levels of approximately 7000 proteins. A novel proprietary machine learning approach was developed on a subset of samples (training set; n = 110) and then was tested on a blind independent validation set (n = 74). Results: A computational model was developed on the proteomic data by identifying patient-specific Resistance Associated Proteins (RAPs). Focusing on differentially expressed proteins between responders and non-responders, a protein was defined as a RAP in a given patient based on its expression level in the patient relative to the expression distribution of the RAP in responders and non-responders. The probability of response to ICB treatment was determined based on the patient’s RAP profile together with 4 clinical parameters. The RAP-based machine learning model successfully stratified between patients with prolonged and limited benefit with a hazard ratio (HR) of 4.5 (confidence interval 2.07-9.77; p-value < 0.0001) and 2.27 (confidence interval 1.7-4.03; p-value = 0.004) for overall survival and progression free survival, respectively. Each patient displayed a resistance map comprised of a unique combination of RAPs, suggesting a new approach for personalized medicine based on patient-specific pathway blockade. For example, a patient with KDR and IL-6 defined as RAPs may benefit from a clinical trial that targets any of these RAPS in combination with ICB. Last, an exploration into the biological functions of the identified RAPs revealed specific biological processes in each response group, including splicing, complement system, coagulation and signaling. Conclusions: We have developed a novel computational approach based on proteomic profiling of liquid biopsies for predicting response to ICB treatment in NSCLC patients. Our approach also sheds light on patient-specific resistance mechanisms, potentially enabling personalized treatment options and patient monitoring over time.

Machine-learning of complex evolutionary signals improves classification of SNVs

Conservation is a strong predictor for the pathogenicity of single-nucleotide variants (SNVs). However, some positions that present complex conservation patterns across vertebrates stray from this paradigm. Here, we analyzed the association between complex conservation patterns and the pathogenicity of SNVs in the 115 disease-genes that had sufficient variant data. We show that conservation is not a one-rule-fits-all solution since its accuracy highly depends on the analyzed set of species and genes. For example, pairwise comparisons between the human and 99 vertebrate species showed that species differ in their ability to predict the clinical outcomes of variants among different genes using conservation. Furthermore, certain genes were less amenable for conservation-based variant prediction, while others demonstrated species that optimize prediction. These insights led to developing EvoDiagnostics, which uses the conservation against each species as a feature within a random-forest machine-learning classification algorithm. EvoDiagnostics outperformed traditional conservation algorithms, deep-learning based methods and most ensemble tools in every prediction-task, highlighting the strength of optimizing conservation analysis per-species and per-gene. Overall, we suggest a new and a more biologically relevant approach for analyzing conservation, which improves prediction of variant pathogenicity.

Exploring the Mechanisms Underlying the Cardiotoxic Effects of Immune Checkpoint Inhibitor Therapies

Adaptive immune response modulation has taken a central position in cancer therapy in recent decades. Treatment with immune checkpoint inhibitors (ICIs) is now indicated in many cancer types with exceptional results. The two major inhibitory pathways involved are cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and programmed cell death protein 1 (PD-1). Unfortunately, immune activation is not tumor-specific, and as a result, most patients will experience some form of adverse reaction. Most immune-related adverse events (IRAEs) involve the skin and gastrointestinal (GI) tract; however, any organ can be involved. Cardiotoxicity ranges from arrhythmias to life-threatening myocarditis with very high mortality rates. To date, most treatments of ICI cardiotoxicity include immune suppression, which is also not cardiac-specific and may result in hampering of tumor clearance. Understanding the mechanisms behind immune activation in the heart is crucial for the development of specific treatments. Histological data and other models have shown mainly CD4 and CD8 infiltration during ICI-induced cardiotoxicity. Inhibition of CTLA4 seems to result in the proliferation of more diverse T0cell populations, some of which with autoantigen recognition. Inhibition of PD-1 interaction with PD ligand 1/2 (PD-L1/PD-L2) results in release from inhibition of exhausted self-recognizing T cells. However, CTLA4, PD-1, and their ligands are expressed on a wide range of cells, indicating a much more intricate mechanism. This is further complicated by the identification of multiple co-stimulatory and co-inhibitory signals, as well as the association of myocarditis with antibody-driven myasthenia gravis and myositis IRAEs. In this review, we focus on the recent advances in unraveling the complexity of the mechanisms driving ICI cardiotoxicity and discuss novel therapeutic strategies for directly targeting specific underlying mechanisms to reduce IRAEs and improve outcomes.

Phase 2 single arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated classical Kaposi Sarcoma (cKS)

BACKGROUND

Classical Kaposi Sarcoma (cKS) is a rare HHV8-associated sarcoma with limited treatment options. We evaluated the efficacy and safety of nivolumab in combination with ipilimumab (Nivo/Ipi) in patients with previously treated progressive cKS.

PATIENTS AND METHODS

cKS pts with progressive disease after > 1 lines of systemic therapy and measurable disease by PET/CT and/or physical examination received nivolumab 240mg every two weeks and ipilimumab 1mg/kg every six weeks until progression or toxicity for a maximum of 24 months. The primary endpoint was overall response rate (ORR); secondary endpoints included 6-months progression free survival rate (PFS) and safety. Immune correlates were explored using IHC, DNAseq (596/648 genes) and RNAseq (exome capture transcriptome) of tumor specimens and matched blood.

RESULTS

Eighteen male patients (median age 76.5) were enrolled between April 2018 and Dec 2020. At a median follow up of 24.4 months, ORR by RECIST v1.1 was 87%. Metabolic complete response as assessed by PET CT was observed in 8 of 13 (62%) evaluable patients. 6/13 achieved pathological CR post treatment. In two patients, palliative limb amputation was prevented. Median PFS was not reached. The 6mo and 12m PFS rate was 76.5% and 58.8%, respectively. Only four patients (22%) experienced grade 3-4 adverse events. The most frequent genomic alteration was biallelic copy number loss of FOX1A gene. The majority of tumors carried a low TMB, were microsatellite stable (MSS), MMR proficient, did not express PD-L1 and displayed only low lymphocytic infiltrates, rendering them immunologically "cold".

CONCLUSIONS

This prospectively designed phase II study of nivolumab and ipilimumab demonstrates promising activity of this combination in progressive cKS representing a new treatment option in this population.

Case report: Robust response of metastatic clear cell sarcoma treated with cabozantinib and immunotherapy

Clear Cell Sarcoma (CCS), also referred to as malignant melanoma of soft parts, is a rare and aggressive malignant tumor. It comprises 1% of all soft tissue sarcomas and is known to be radio- and chemotherapy resistant. CCS shares morphological and immunohistochemical features with malignant melanoma, including melanin biosynthesis and melanocytic markers. However, it is distinct for the presence of EWSR1-ATF1 translocation which activates MITF transcription factor. We report here of an aggressive case of CCS in a 9-year-old patient, which demonstrates the critical role of molecular analysis in the diagnosis and treatment of uncommon cancer variants in the era of personalized medicine. The EWSR1-ATF1 translocation induces pathological c-Met activation, and so, following unsuccessful CTLA4 and PD-1 blockade immunotherapy, the child received cabozantinib, a small molecule tyrosine kinase inhibitor, with the intent to block c-Met oncogenic effect. In parallel, active immunization, using hapten di-nitrophenyl modified autologous tumor cells was administered with monotherapy PD-1 inhibitor nivolumab. Under this "triplet" therapy, the patient attained an initial partial response and was progression-free for 2 years, in good performance status and resumed schooling. Based on our observation, cabozantinib can be used as an effective and potentially life-prolonging treatment in CCS. We suggest that priming the child's immune system using her autologous tumor and combating T cell exhaustion with PD-1 blockade may have synergized with the targeted therapy. Combining targeted and immunotherapy is a rapidly growing practice in solid tumors and provides a glimpse of hope in situations that previously lacked any treatment option.

Antitumor activity of ipilimumab or BRAF ± MEK inhibition after pembrolizumab treatment in patients with advanced melanoma: analysis from KEYNOTE-006

BACKGROUND

Antitumor activity of ipilimumab or BRAF ± MEK inhibitors (BRAFi ± MEKi) following pembrolizumab administration in melanoma is poorly characterized.

PATIENTS AND METHODS

In the phase III KEYNOTE-006 study, patients with unresectable stage III/IV melanoma received pembrolizumab (10 mg/kg) once every 2 or 3 weeks (Q3W) or ipilimumab (3 mg/kg) Q3W. The current post hoc analysis evaluates outcomes with ipilimumab or BRAFi ± MEKi as first subsequent systemic therapy after pembrolizumab administration and includes patients who completed or discontinued pembrolizumab after one or more dose. Pembrolizumab arms were pooled.

RESULTS

At data cut-off (4 December 2017), median follow-up was 46.9 months. Of 555 pembrolizumab-treated patients, first subsequent therapy was ipilimumab for 103 (18.6%) and BRAFi ± MEKi for 59 (10.6%) [33 received BRAFi + MEKi, 26 BRAFi alone; 37 (62.7%) were BRAFi ± MEKi naïve]. In the subsequent ipilimumab group, ORR with previous pembrolizumab was 17.5% [1 complete response (CR); 17 partial response (PR)]; 79.6% had discontinued pembrolizumab due to progressive disease (PD); median overall survival (OS) was 21.5 months. ORR with subsequent ipilimumab was 15.5%; 11/16 responses (8 CRs; 3 PRs) were ongoing. ORR with subsequent ipilimumab was 9.7% for patients with PD as best response to pembrolizumab. Median OS from ipilimumab initiation was 9.8 months. In the subsequent BRAFi ± MEKi group, ORR with previous pembrolizumab was 13.5% (8 PR); 76.3% had discontinued pembrolizumab due to PD; median OS was 17.9 months. ORR with subsequent BRAFi ± MEKi was 30.5%, 7/18 responses (4 CR, 3 PR) were ongoing. Median OS from BRAFi ± MEKi initiation was 12.9 months. ORR for BRAFi ± MEKi-naïve patients who received subsequent BRAFi ± MEKi was 43.2%; 6/16 were ongoing (3 CR, 3 PR).

CONCLUSIONS

Ipilimumab and BRAFi ± MEKi have antitumor activity as first subsequent therapy after pembrolizumab in patients with advanced melanoma.

Combined presentation and immunogenicity analysis reveals a recurrent RAS.Q61K neoantigen in melanoma

Neoantigens are now recognized drivers of the antitumor immune response. Recurrent neoantigens, shared among groups of patients, have thus become increasingly coveted therapeutic targets. Here, we report on the data-driven identification of a robustly presented, immunogenic neoantigen that is derived from the combination of HLA-A*01:01 and RAS.Q61K. Analysis of large patient cohorts indicated that this combination applies to 3% of patients with melanoma. Using HLA peptidomics, we were able to demonstrate robust endogenous presentation of the neoantigen in 10 tumor samples. We detected specific reactivity to the mutated peptide within tumor-infiltrating lymphocytes (TILs) from 2 unrelated patients, thus confirming its natural immunogenicity. We further investigated the neoantigen-specific clones and their T cell receptors (TCRs) via a combination of TCR sequencing, TCR overexpression, functional assays, and single-cell transcriptomics. Our analysis revealed a diverse repertoire of neoantigen-specific clones with both intra- and interpatient TCR similarities. Moreover, 1 dominant clone proved to cross-react with the highly prevalent RAS.Q61R variant. Transcriptome analysis revealed a high association of TCR clones with specific T cell phenotypes in response to cognate melanoma, with neoantigen-specific cells showing an activated and dysfunctional phenotype. Identification of recurrent neoantigens and their reactive TCRs can promote "off-the-shelf" precision immunotherapies, alleviating limitations of personalized treatments.

KEYNOTE-022 part 3: a randomized, double-blind, phase 2 study of pembrolizumab, dabrafenib, and trametinib in BRAF-mutant melanoma

Background

In the KEYNOTE-022 study, pembrolizumab with dabrafenib and trametinib (triplet) improved progression-free survival (PFS) versus placebo with dabrafenib and trametinib (doublet) without reaching statistical significance. Mature results on PFS, duration of response (DOR), and overall survival (OS) are reported.

Methods

The double-blind, phase 2 part of KEYNOTE-022 enrolled patients with previously untreated BRAF^V600E/K-mutated advanced melanoma from 22 sites in seven countries. Patients were randomly assigned 1:1 to intravenous pembrolizumab (200 mg every 3 weeks) or placebo plus dabrafenib (150 mg orally two times per day) and trametinib (2 mg orally one time a day). Primary endpoint was PFS. Secondary endpoints were objective response rate, DOR, and OS. Efficacy was assessed in the intention-to-treat population, and safety was assessed in all patients who received at least one dose of study drug. This analysis was not specified in the protocol.

Results

Between November 30, 2015 and April 24, 2017, 120 patients were randomly assigned to triplet (n=60) or doublet (n=60) therapy. With 36.6 months of follow-up, median PFS was 16.9 months (95% CI 11.3 to 27.9) with triplet and 10.7 months (95% CI 7.2 to 16.8) with doublet (HR 0.53; 95% CI 0.34 to 0.83). With triplet and doublet, respectively, PFS at 24 months was 41.0% (95% CI 27.4% to 54.2%) and 16.3% (95% CI 8.1% to 27.1%); median DOR was 25.1 months (95% CI 14.1 to not reached) and 12.1 months (95% CI 6.0 to 15.7), respectively. Median OS was not reached with triplet and was 26.3 months with doublet (HR 0.64; 95% CI 0.38 to 1.06). With triplet and doublet, respectively, OS at 24 months was 63.0% (95% CI 49.4% to 73.9%) and 51.7% (95% CI 38.4% to 63.4%). Grade 3–5 treatment-related adverse events (TRAEs) occurred in 35 patients (58%, including one death) receiving triplet and 15 patients (25%) receiving doublet.

Conclusion

In BRAF^V600E/K-mutant advanced melanoma, pembrolizumab plus dabrafenib and trametinib substantially improved PFS, DOR, and OS with a higher incidence of TRAEs. Interpretation of these results is limited by the post hoc nature of the analysis.

TP53 missense mutations in PDAC are associated with enhanced fibrosis and an immunosuppressive microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer, which is refractory to all currently available treatments and bears dismal prognosis. About 70% of all PDAC cases harbor mutations in the TP53 tumor suppressor gene. Many of those are missense mutations, resulting in abundant production of mutant p53 (mutp53) protein in the cancer cells. Analysis of human PDAC patient data from The Cancer Genome Atlas (TCGA) revealed a negative association between the presence of missense mutp53 and infiltration of CD8+ T cells into the tumor. Moreover, CD8+ T cell infiltration was negatively correlated with the expression of fibrosis-associated genes. Importantly, silencing of endogenous mutp53 in KPC cells, derived from mouse PDAC tumors driven by mutant Kras and mutp53, down-regulated fibrosis and elevated CD8+ T cell infiltration in the tumors arising upon orthotopic injection of these cells into the pancreas of syngeneic mice. Moreover, the tumors generated by mutp53-silenced KPC cells were markedly smaller than those elicited by mutp53-proficient control KPC cells. Altogether, our findings suggest that missense p53 mutations may contribute to worse PDAC prognosis by promoting a more vigorous fibrotic tumor microenvironment and impeding the ability of the immune system to eliminate the cancer cells.

Long-term real-world experience with ipilimumab and non-ipilimumab therapies in advanced melanoma: the IMAGE study

Background

Ipilimumab has shown long-term overall survival (OS) in patients with advanced melanoma in clinical trials, but robust real-world evidence is lacking. We present long-term outcomes from the IMAGE study (NCT01511913) in patients receiving ipilimumab and/or non-ipilimumab (any approved treatment other than ipilimumab) systemic therapies.

Methods

IMAGE was a multinational, prospective, observational study assessing adult patients with advanced melanoma treated with ipilimumab or non-ipilimumab systemic therapies between June 2012 and March 2015 with ≥3 years of follow-up. Adjusted OS curves based on multivariate Cox regression models included covariate effects. Safety and patient-reported outcomes were assessed.

Results

Among 1356 patients, 1094 (81%) received ipilimumab and 262 (19%) received non-ipilimumab index therapy (systemic therapy [chemotherapy, anti–programmed death 1 antibodies, or BRAF ± MEK inhibitors], radiotherapy, and radiosurgery). In the overall population, median age was 64 years, 60% were male, 78% were from Europe, and 78% had received previous treatment for advanced melanoma. In the ipilimumab-treated cohort, 780 (71%) patients did not receive subsequent therapy (IPI-noOther) and 314 (29%) received subsequent non-ipilimumab therapy (IPI-Other) on study. In the non-ipilimumab–treated cohort, 205 (78%) patients remained on or received other subsequent non-ipilimumab therapy (Other-Other) and 57 (22%) received subsequent ipilimumab therapy (Other-IPI) on study. Among 1151 patients who received ipilimumab at any time during the study (IPI-noOther, IPI-Other, and Other-IPI), 296 (26%) reported CTCAE grade ≥ 3 treatment-related adverse events, most occurring in year 1. Ipilimumab-treated and non-ipilimumab–treated patients who switched therapy (IPI-Other and Other-IPI) had longer OS than those who did not switch (IPI-noOther and Other-Other). Patients with prior therapy who did not switch therapy (IPI-noOther and Other-Other) showed similar OS. In treatment-naive patients, those in the IPI-noOther group tended to have longer OS than those in the Other-Other group. Patient-reported outcomes were similar between treatment cohorts.

Conclusions

With long-term follow-up (≥ 3 years), safety and OS in this real-world population of patients treated with ipilimumab 3 mg/kg were consistent with those reported in clinical trials. Patient-reported quality of life was maintained over the study period. OS analysis across both pretreated and treatment-naive patients suggested a beneficial role of ipilimumab early in treatment.

Trial registration

ClinicalTrials.gov, NCT01511913. Registered January 19, 2012 – Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT01511913

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08032-y.

PD-L1 recruits phospholipase C and enhances tumorigenicity of lung tumors harboring mutant forms of EGFR

Cancer immunotherapy focuses on inhibitors of checkpoint proteins, such as programmed death ligand 1 (PD-L1). Unlike RAS-mutated lung cancers, EGFR mutant tumors have a generally low response to immunotherapy. Because treatment outcomes vary by EGFR allele, intrinsic and microenvironmental factors may be involved. Among all non-immunological signaling pathways surveyed in patients’ datasets, EGFR signaling is best associated with high PD-L1. Correspondingly, active EGFRs stabilize PD-L1 transcripts and depletion of PD-L1 severely inhibits EGFR-driven tumorigenicity and metastasis in mice. The underlying mechanisms involve the recruitment of phospholipase C-γ1 (PLC-γ1) to a cytoplasmic motif of PD-L1, which enhances PLC-γ1 activation by EGFR. Once stimulated, PLC-γ1 activates calcium flux, Rho GTPases, and protein kinase C, collectively promoting an aggressive phenotype. Anti-PD-L1 antibodies can inhibit these intrinsic functions of PD-L1. Our results portray PD-L1 as a molecular amplifier of EGFR signaling and improve the understanding of the resistance of EGFR⁺ tumors to immunotherapy.

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Unlike promoter-mediated PD-L1 induction by IFN-γ, EGFR rapidly stabilizes PD-L1 mRNA

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Once induced, PD-L1 enhances metastasis in vivo and chemotaxis toward EGF

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PD-L1 physically binds with and enhances activation of phospholipase C-γ1 by EGFR

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PLC-γ1 binds a PD-L1’s cytoplasmic segment implicated in protection from cytotoxicity

Identification of bacteria-derived HLA-bound peptides in melanoma

A variety of species of bacteria are known to colonize human tumours1-11, proliferate within them and modulate immune function, which ultimately affects the survival of patients with cancer and their responses to treatment12-14. However, it is not known whether antigens derived from intracellular bacteria are presented by the human leukocyte antigen class I and II (HLA-I and HLA-II, respectively) molecules of tumour cells, or whether such antigens elicit a tumour-infiltrating T cell immune response. Here we used 16S rRNA gene sequencing and HLA peptidomics to identify a peptide repertoire derived from intracellular bacteria that was presented on HLA-I and HLA-II molecules in melanoma tumours. Our analysis of 17 melanoma metastases (derived from 9 patients) revealed 248 and 35 unique HLA-I and HLA-II peptides, respectively, that were derived from 41 species of bacteria. We identified recurrent bacterial peptides in tumours from different patients, as well as in different tumours from the same patient. Our study reveals that peptides derived from intracellular bacteria can be presented by tumour cells and elicit immune reactivity, and thus provides insight into a mechanism by which bacteria influence activation of the immune system and responses to therapy.

Alternative Splicing of the Inhibitory Immune Checkpoint Receptor SLAMF6 Generates a Dominant Positive Form, Boosting T-cell Effector Functions

SLAMF6 is a homotypic receptor of the Ig-superfamily associated with progenitor-exhausted T cells. Here we show that in humans, SLAMF6 has three splice isoforms involving its V-domain. Although the canonical receptor inhibited T-cell activation through SAP recruitment, the short isoform SLAMF6^Δ17-65 had a strong agonistic effect. The costimulatory action depended on protein phosphatase SHP1 and led to a cytotoxic molecular profile mediated by the expression of TBX21 and RUNX3. Patients treated with immune checkpoint blockade showed a shift toward SLAMF6^Δ17-65 in peripheral blood T cells. We developed splice-switching antisense oligonucleotides (ASO) designed to target the relevant SLAMF6 splice junction. Our ASOs enhanced SLAMF6^Δ17-65 expression in human tumor-infiltrating lymphocytes and improved their capacity to inhibit human melanoma in mice. The yin-yang relationship of SLAMF6 splice isoforms may represent a balancing mechanism that could be exploited to improve cancer immunotherapy.

Abstract CT134: Tilsotolimod engages the TLR9 pathway to promote antigen presentation and Type-I IFN signaling in solid tumors

Background: Tilsotolimod, an investigational Toll-like receptor 9 (TLR9) agonist, modulates the tumor immune microenvironment and has single-agent antitumor activity in preclinical models. The ILLUMINATE-101 phase 1b study (NCT03052205) explored the safety, efficacy, and immune effects of intratumoral tilsotolimod in multiple solid tumors.

Methods: Adults with a histologically- or cytologically-confirmed diagnosis of cancer not amenable to curative therapies received intratumoral tilsotolimod 8, 16, 23, or 32 mg into a single lesion on Days 1, 8, and 15 of Cycle 1 and Day 1 of each subsequent 3-week cycle, for up to 17 cycles. Additionally, patients with advanced melanoma were enrolled into an expansion cohort at the recommended phase 2 dose of 8 mg. The primary objective was to characterize safety (dose escalation cohort) and efficacy (expansion cohort). Secondary objectives included pharmacokinetics of tilsotolimod. Immunological assessment of injected and non-injected tumors was an exploratory objective. Blood samples and tumor biopsies of injected lesions were obtained at baseline and 24 hours post treatment for immune analyses.

Results: A total of 54 patients were enrolled. Of the 38 patients in the dose escalation cohort, 35 had metastatic disease. Patients in this cohort had a median of 7 prior lines of treatment, and the most common cancer types were pancreatic (12 patients) and colorectal (7 patients). All 16 patients in the melanoma cohort had metastatic disease with a median of 3 lines of prior therapy, and 10 patients had elevated LDH. Injected lesions were deep and required interventional radiology in 52 of 54 patients. No dose-limiting toxicities were observed. The most common treatment-related adverse events were pyrexia, fatigue, chills, nausea, and vomiting. Compared to pretreatment, biopsies of injected tumors at 24 hours showed increased activation of the Type-I IFN pathway, upregulation of MHC class I/II, IFNγ expression, and expression of multiple immune checkpoints (i.e. PD-1, LAG3). Of the 35 evaluable patients in the dose escalation cohort, 12 (34%) achieved a best overall response of stable disease (SD). Of the 16 evaluable patients in the melanoma cohort, 3 had SD, 1 who had a 35% tumor reduction with no confirmatory scan.

Conclusions: Tilsotolimod was generally well tolerated and induced alterations in the tumor microenvironment, including immune checkpoint upregulation, activation of dendritic cells, and induction of Type-I IFN signaling. Additional clinical studies of tilsotolimod in combination with checkpoint inhibitors are underway (NCT03445533, NCT03865082, and NCT02644967).

Citation Format: Hani M. Babiker, Vivek Subbiah, Asim Ali, Alain Algazi, Jacob Schachter, Michal Lotem, Corinne Maurice-Dror, Daniel Hendler, Shah Rahimian, Hans Minderman, Cara Haymaker, Chantale Bernatchez, Ravi Murthy, Rolf Hultsch, Nadia Caplan, Gregory Woodhead, Charles Hennemeyer, Sri Chunduru, Peter Anderson, Adi Diab, Erkut Borazanci, Igor Puzanov. Tilsotolimod engages the TLR9 pathway to promote antigen presentation and Type-I IFN signaling in solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT134.

A phase II single-arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated classical Kaposi sarcoma (CKS)

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Background: CKS is a mesenchymal neoplasm associated with HHV8 infection. Though recombinant INFa is approved for treatment of AIDS-related KS, data is limited regarding the role of immune modulation in CKS therapy. Based on favorable responses in viral-induced cancers, we hypothesized that CTLA-4 and PD-1 blockade can induce tumor regression in CKS. We present pre-planned interim analysis of a phase II study of Nivo/Ipi in previously treated progressive CKS. Methods: CKS pts with progressive disease after > 1 line of systemic therapy and measurable disease received nivolumab 240mg d1,15,28 and ipilimumab 1mg/kg d1 q42 days until progression or toxicity. The primary endpoint was overall response rate (ORR) evaluated clinically, radiologically (RECIST) and metabolically (FDG-PET). Secondary endpoints include 6-months progression free survival rate (PFS) and safety. Exploratory endpoints included PD-L1/MMR by IHC, DNAseq (596 genes)/RNAseq (whole transcriptome) of tumor and matched blood specimens to explore CKS genomic traits and IO correlates: TMB and MSI status, MMR and PD-L1 protein expression, and immune gene transcript expression (PD-1, PD-L1, CTLA-4, and others) (Tempus Labs, Chicago, IL, USA). Results: Fifteen patients were enrolled and evaluable (Apr18-Jan20). Median age 72.5 (61-81), all male. At a median FU of 15.7 mo ORR as per RECIST was 66% (9 pts PR, 1 pt CR, 2 pts SD, 3 pts NE). Clinical ORR was 87% and metabolic ORR was 60%. Median PFS was not reached, 6mo PFS rate was 85% and 1y PFS rate was 75%. The safety profile was as expected with all pts experiencing G1 toxicity, 3 pts with G2 toxicity (1 hepatic, 2 asymptomatic lipase increase) and 2 pts with G3 toxicity (1 colitis, 1 asymptomatic lipase increase). One SAE was reported (TIA considered not related to therapy) and treatment was discontinued in 3 pts. Correlative results are available for 8 pts showing a trend for copy number loss in genes with tumor-suppressive activity (FOXA1, ELF3), no PDL1 expression, low TMB, microsatellite stability, but marked overexpression of CTLA-4, PD-1, PDL-1, CD40, OX40 and LAG3 RNA immune transcripts. Conclusions: The interim analysis of this prospective phase II study of nivolumab and low-dose ipilimumab demonstrates promising activity in progressive CKS, with 66% ORR and a 6mo PFS rate of 85%. Toxicity profile is as expected in this class of drugs. Correlative studies are preliminary, but warrant further investigation into genomic traits and immune gene expression profiles. Clinical trial information: NCT03219671. Clinical trial information: NCT03219671 .

Long-term survival from pembrolizumab (pembro) completion and pembro retreatment: Phase III KEYNOTE-006 in advanced melanoma

10013

Background: 5-year follow-up of the phase 3 KEYNOTE-006 study (NCT01866319) showed pembro improved OS vs ipilimumab (ipi) in patients (pts) with advanced melanoma. 3-y OS rate from pembro completion for pts who completed 2 y of pembro was 93.8%. Results with 8 mo of additional follow-up are presented to inform clinical care. Methods: Eligible pts with ipi-naive advanced melanoma, ≤1 prior therapy for BRAF-mutant disease, and ECOG PS 0 or 1 were randomized to pembro 10 mg/kg Q2W or Q3W for ≤2 y or ipi 3 mg/kg Q3W for 4 doses. Pts discontinuing pembro with CR, PR, or SD after ≥94 weeks were considered pts with 2-y pembro. Pts who stopped pembro with SD, PR or CR could receive ≤12 mo of additional pembro (2nd course) upon disease progression if still eligible. ORR was assessed per immune-related response criteria by investigator review. OS was estimated using the Kaplan-Meier method. Pembro arm data were pooled. Post hoc ITT efficacy analyses are shown. Results: Median follow-up from randomization to data cutoff (Jul 31, 2019) was 66.7 mo in the pembro and 66.9 mo in the ipi arms. OS outcomes are shown in Table. For the 103 pts with 2-y pembro (30 CR, 63 PR, 10 SD), median follow-up from completion was 42.9 mo (95% CI, 39.9-46.3).Median DOR was not reached. 36-mo OS from pembro completion was 100% (95% CI, 100.0-100.0) for pts with CR, 94.8% (95% CI, 84.7-98.3) for pts with PR, and 66.7% (95% CI, 28.2-87.8) for pts with SD. 15 pts received 2nd-course pembro; BOR in 1st course was 6 CR, 6 PR, and 3 SD. Median time from end of 1st course to start of 2ndcourse was 24.5 mo (range, 4.9-41.4). Median follow-up in pts who received 2nd-course pembro was 25.3 mo (range, 3.5-39.4). Median duration of 2nd-course pembro was 8.3 mo (range, 1.4-12.6). BOR on 2ndcourse was 3 CR, 5 PR (ongoing responses, 7 pts), 3 SD (ongoing, 2 pts), and 2 PD (1 death); 2 pts pending. Conclusions: Pembro improves the long-term survival vs ipi in pts with advanced melanoma, with all pts who completed therapy in CR still alive at 5 years. Retreatment with pembro at progression in pts who stopped at SD or better can provide additional clinical benefit in a majority of pts. Clinical trial information: NCT01866319. [Table: see text]

Predictive Gene Signature for Pyrazolopyrimidine Derivative c-Src Inhibitor 10a Sensitivity in Melanoma Cells

Melanoma is a highly aggressive cancer with poor prognosis. Although more than 80% of melanomas harbor an activating mutation in genes within the MAPK pathway, which are mutually exclusive, usefulness of therapies targeting MAPK pathway are impeded by innate and/or acquired resistance in most patients. In this study, using melanoma cells, we report the efficacy of a recently developed pyrazolo[3,4-d]pyrimidine derived c-Src inhibitor 10a and identify a molecular signature which is predictive of 10a chemosensitivity. We show that the expression of TMED7, PLOD2, XRCC5, and NSUN5 are candidate biomarkers for 10a sensitivity. Although an undifferentiated/mesenchymal/invasive status of melanoma cells is associated with resistance to 10a, we show here for the first time that melanoma cells can be sensitized to 10a via treatment with valproic acid, a histone deacetylase inhibitor.

Checkpoint inhibitors: Better outcomes among advanced cutaneous head and neck melanoma patients

OBJECTIVE

The aim of this study was to investigate if the treatment outcomes of checkpoint inhibitors (CPI) in patients with advanced-stage skin head and neck melanoma (HNM) differs from outcomes in patients with non-HNM.

DESIGN

A retrospective cohort study of patients with unresectable AJCC stage III and stage IV, who received CPI between 2010 and 2017.

PARTICIPANTS

Overall, 122 unresectable AJCC stage III and metastatic stage IV melanoma adult patients were treated with CPI during the study period (consecutive patients). The HNM group of patients was comparable with limbs and trunk melanoma group except different distant metastatic (M1a/b/c/d) pattern (p = 0.025).

MAIN OUTCOMES

Comparison of overall survival and clinical response to CPI in patients with advanced-stage skin melanoma of the head and neck with non-HNM.

RESULTS

We analyzed 38 patients with melanoma arising in the head and neck skin regions, 33 with melanoma of limbs and 51 with trunk melanoma. Most of the head and neck patients were men (89.5%), the average age of melanoma diagnosis was 61.4±16.7 years (range 16.4-85.6). More than a third of HNM group of patients (36.8%) were 70 years and older. Overall response rate (ORR) to CPI was 50% (CR 31.6% and PR 18.4%) in the head and neck study group of patients, compared to an ORR of 36.3% and 23.5% in melanoma of the limbs and of the trunk, respectively (p = 0.03). The median overall survival of HNM group of patients was 60.2±6.3 months, CI 95% [47.7-72.7], 63% were alive at 30 months, reaching a plateau. Whereas, the median survival time of limbs and trunk melanoma were 51.2 and 53.4 months, which did not reach significance.

CONCLUSIONS AND RELEVANCE

Response rate to CPI is significantly improved in patients with melanoma of the head and neck and they have a trend towards improved, long standing, overall survival.

SLAMF6​ deficiency augments tumor killing and skews toward an effector phenotype revealing it as a novel T cell checkpoint

SLAMF6 is a homotypic receptor of the Ig-superfamily whose exact role in immune modulation has remained elusive. Its constitutive expression on resting and activated T cells precludes it from being a bona fide exhaustion marker. By breeding Pmel-1 mice with SLAMF6 -/- mice, we generated donors for T cells lacking SLAMF6 and expressing a transgenic TCR for gp100-melanoma antigen. Activated Pmel-1xSLAMF6 -/- CD8+ T cells displayed improved polyfunctionality and strong tumor cytolysis. T-bet was the dominant transcription factor in Pmel-1 x SLAMF6 -/- cells, and upon activation, they acquired an effector-memory phenotype. Adoptive transfer of Pmel-1 x SLAMF6 -/- T cells to melanoma-bearing mice resulted in lasting tumor regression in contrast to temporary responses achieved with Pmel-1 T cells. LAG-3 expression was elevated in the SLAMF6 -/- cells, and the addition of the LAG-3-blocking antibody to the adoptive transfer protocol improved the SLAMF6 -/- T cells and expedited the antitumor response even further. The results from this study support the notion that SLAMF6 is an inhibitory immune receptor whose absence enables powerful CD8+ T cells to eradicate tumors.

Immunotherapy Potentiates the Effect of Chemotherapy in Metastatic Melanoma-A Retrospective Study

Melanoma survival increased with targeted- and immunotherapy agents, yet most patients ultimately progress and require salvage therapy. In our experience, some progressive disease patients on immune-checkpoint inhibitors (ICIs) demonstrate deep and sustained responses to chemotherapy. We hypothesized that ICIs improve the response to subsequent chemotherapy in metastatic melanoma. We conducted a retrospective study to compare the efficacy of chemotherapy given with prior immunotherapy, to its efficacy given without it. We measured progression free survival (PFS), overall survival, and response rate. Immune-monitoring was performed on sequential peripheral blood mononuclear cell samples taken from a chemotherapy-responsive patient. The chemotherapy post-immunotherapy group (CpI) included 11 patients, the chemotherapy without prior immunotherapy (CNPI) group included 24 patients. Median PFS was 5.2 months in the CpI vs. 2.5 months in the CNPI groups; HR 0.37 [95% Confidence interval (CI) 0.144–0.983], P = 0.046. Immune-monitoring showed an increased proportion of CD8⁺ cells, with elevated PD-1 and CD69 expression, while on chemotherapy, as compared with all-time points on ICIs, suggesting immune-activation. Immunotherapy potentiates the effect of chemotherapy in metastatic melanoma possibly through activation of CD8⁺ T cells.

Predicting response to pembrolizumab in metastatic melanoma by a new personalization algorithm

BACKGROUND

At present, immune checkpoint inhibitors, such as pembrolizumab, are widely used in the therapy of advanced non-resectable melanoma, as they induce more durable responses than other available treatments. However, the overall response rate does not exceed 50% and, considering the high costs and low life expectancy of nonresponding patients, there is a need to select potential responders before therapy. Our aim was to develop a new personalization algorithm which could be beneficial in the clinical setting for predicting time to disease progression under pembrolizumab treatment.

METHODS

We developed a simple mathematical model for the interactions of an advanced melanoma tumor with both the immune system and the immunotherapy drug, pembrolizumab. We implemented the model in an algorithm which, in conjunction with clinical pretreatment data, enables prediction of the personal patient response to the drug. To develop the algorithm, we retrospectively collected clinical data of 54 patients with advanced melanoma, who had been treated by pembrolizumab, and correlated personal pretreatment measurements to the mathematical model parameters. Using the algorithm together with the longitudinal tumor burden of each patient, we identified the personal mathematical models, and simulated them to predict the patient's time to progression. We validated the prediction capacity of the algorithm by the Leave-One-Out cross-validation methodology.

RESULTS

Among the analyzed clinical parameters, the baseline tumor load, the Breslow tumor thickness, and the status of nodular melanoma were significantly correlated with the activation rate of CD8+ T cells and the net tumor growth rate. Using the measurements of these correlates to personalize the mathematical model, we predicted the time to progression of individual patients (Cohen's κ = 0.489). Comparison of the predicted and the clinical time to progression in patients progressing during the follow-up period showed moderate accuracy (R² = 0.505).

CONCLUSIONS

Our results show for the first time that a relatively simple mathematical mechanistic model, implemented in a personalization algorithm, can be personalized by clinical data, evaluated before immunotherapy onset. The algorithm, currently yielding moderately accurate predictions of individual patients' response to pembrolizumab, can be improved by training on a larger number of patients. Algorithm validation by an independent clinical dataset will enable its use as a tool for treatment personalization.

Pembrolizumab versus ipilimumab in advanced melanoma (KEYNOTE-006): post-hoc 5-year results from an open-label, multicentre, randomised, controlled, phase 3 study

BACKGROUND

Pembrolizumab improved progression-free survival and overall survival versus ipilimumab in patients with advanced melanoma and is now a standard of care in the first-line setting. However, the optimal duration of anti-PD-1 administration is unknown. We present results from 5 years of follow-up of patients in KEYNOTE-006.

METHODS

KEYNOTE-006 was an open-label, multicentre, randomised, controlled, phase 3 study done at 87 academic institutions, hospitals, and cancer centres in 16 countries. Patients aged at least 18 years with Eastern Cooperative Oncology Group performance status of 0 or 1, ipilimumab-naive histologically confirmed advanced melanoma with known BRAF^V600 status and up to one previous systemic therapy were randomly assigned (1:1:1) to intravenous pembrolizumab 10 mg/kg every 2 weeks or every 3 weeks or four doses of intravenous ipilimumab 3 mg/kg every 3 weeks. Treatments were assigned using a centralised, computer-generated allocation schedule with blocked randomisation within strata. Exploratory combination of data from the two pembrolizumab dosing regimen groups was not protocol-specified. Pembrolizumab treatment continued for up to 24 months. Eligible patients who discontinued pembrolizumab with stable disease or better after receiving at least 24 months of pembrolizumab or discontinued with complete response after at least 6 months of pembrolizumab and then progressed could receive an additional 17 cycles of pembrolizumab. Co-primary endpoints were overall survival and progression-free survival. Efficacy was analysed in all randomly assigned patients, and safety was analysed in all randomly assigned patients who received at least one dose of study treatment. Exploratory assessment of efficacy and safety at 5 years' follow-up was not specified in the protocol. Data cutoff for this analysis was Dec 3, 2018. Recruitment is closed; the study is ongoing. This study is registered with ClinicalTrials.gov, number NCT01866319.

FINDINGS

Between Sept 18, 2013, and March 3, 2014, 834 patients were enrolled and randomly assigned to receive pembrolizumab (every 2 weeks, n=279; every 3 weeks, n=277), or ipilimumab (n=278). After a median follow-up of 57·7 months (IQR 56·7-59·2) in surviving patients, median overall survival was 32·7 months (95% CI 24·5-41·6) in the combined pembrolizumab groups and 15·9 months (13·3-22·0) in the ipilimumab group (hazard ratio [HR] 0·73, 95% CI 0·61-0·88, p=0·00049). Median progression-free survival was 8·4 months (95% CI 6·6-11·3) in the combined pembrolizumab groups versus 3·4 months (2·9-4·2) in the ipilimumab group (HR 0·57, 95% CI 0·48-0·67, p<0·0001). Grade 3-4 treatment-related adverse events occurred in 96 (17%) of 555 patients in the combined pembrolizumab groups and in 50 (20%) of 256 patients in the ipilimumab group; the most common of these events were colitis (11 [2%] vs 16 [6%]), diarrhoea (ten [2%] vs seven [3%]), and fatigue (four [<1%] vs three [1%]). Any-grade serious treatment-related adverse events occurred in 75 (14%) patients in the combined pembrolizumab groups and in 45 (18%) patients in the ipilimumab group. One patient assigned to pembrolizumab died from treatment-related sepsis.

INTERPRETATION

Pembrolizumab continued to show superiority over ipilimumab after almost 5 years of follow-up. These results provide further support for use of pembrolizumab in patients with advanced melanoma.

FUNDING

Merck Sharp & Dohme.

Abstract CT188: 5-year survival and other long-term outcomes from KEYNOTE-006 study of pembrolizumab (pembro) for ipilimumab (ipi)-naive advanced melanoma

Introduction: Pembro significantly improved OS vs ipi in advanced melanoma in the KEYNOTE-006 study (NCT01866319). We present outcomes from the 5-year follow-up of this study−the longest to date in a randomized phase 3 trial of pembro in advanced cancer. Long-term follow-up for pts completing 2 years of pembro and data for pts treated with a second course (2nd course) of pembro are also reported.

Methods: Eligible pts (N=834) were randomly assigned (1:1:1) to pembro 10 mg/kg Q2W or Q3W for up to 2 years or ipi 3 mg/kg Q3W for 4 doses. Eligible pts who completed pembro or stopped for CR and then progressed could receive an additional 12 mo of pembro if they met inclusion criteria. End points included OS and ORR per irRC by investigator review. Pembro completion was defined as discontinuation with CR, PR, or SD after ≥94 weeks of pembro. Results were pooled from the 2 pembro arms.

Results: At data cutoff (Dec 3, 2018), median follow-up of surviving pts was 57.7 mo (range, 0.03-62.1). Median OS (95% CI) was 32.7 mo (24.5-41.6) in the combined pembro arms (n=556) and 15.9 mo (13.3-22.0) in the ipi arm (n=278) (HR, 0.73). Five-year OS rates (95% CI) were estimated to be 38.7% (34.2-43.1) and 31.0% (25.3-36.9), respectively. For pts receiving first-line pembro, median OS (95% CI) was 38.7 mo (27.3-50.7) in the combined pembro arms (n=368) and 17.1 mo (13.8-26.2) in the ipi arm (n=181) (HR, 0.73); 5-year OS rates (95% CI) were estimated to be 43.2% (38.0-48.3) and 33.0% (25.8-40.3), respectively. A total of 103 (18.5%) pts completed 2 years of pembro; median survival follow-up from pembro completion was 34.5 mo; OS rate at 36 mo was 93.8%. Of the 103 pts, 76 were progression-free and 27 had PD. Median time from pembro end to progression was 16.8 mo (range, 0.99-33.9). Thirteen pts received 2nd course pembro; best overall response (BOR) in 1st course was 6 CR, 6 PR, and 1 SD. Median duration of 2nd-course pembro was 9.7 mo; BOR on 2nd course was 3 CR, 4 PR, 3 SD, and 1 PD (response assessment was pending for 2 pts). All 3 pts with 2nd-course CR and 2 of 4 with PR had ongoing response; the remaining 2 pts who had 2nd-course PR subsequently progressed. Four pts discontinued 2nd-course treatment before 12 mo (2 due to PD, 1 due to G2 interstitial pneumonia, and 1 due to physician decision). Six pts had grade1/2 TRAEs during 2nd-course pembro; there were no grade 3/4 TRAEs or deaths.

Conclusions: Pembro continued to show improved OS vs ipi in 5-year follow-up of pts with advanced melanoma with 43.2% estimated to be alive at 5 years versus 33.0% with ipi. Almost one-fifth of pts completed 2 years of pembro, and 93.8% are estimated to be alive 3 years after pembro completion. Second-course pembro treatment was generally well tolerated and provided additional antitumor activity. These results confirm that 2-year pembro is an effective treatment for pts with advanced melanoma.

Citation Format: Caroline Robert, Jacob Schachter, Georgina V. Long, Ana Arance, Jean-Jacques Grob, Laurent Mortier, Adil Daud, Matteo S. Carlino, Catriona McNeil, Michal Lotem, James Larkin, Paul Lorigan, Bart Neyns, Christian U. Blank, Omid Hamid, Teresa M. Petrella, James Anderson, Clemens Krepler, Scott J. Diede, Antoni Ribas. 5-year survival and other long-term outcomes from KEYNOTE-006 study of pembrolizumab (pembro) for ipilimumab (ipi)-naive advanced melanoma [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 CT188.

A phase II single-arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated Classic Kaposi sarcoma (CKS)

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Background: CKS is an angioproliferative mesenchymal neoplasm causatively associated with human herpes virus 8 infection. Though recombinant IFNa is approved for treatment of AIDS-related KS, data is limited regarding the role of immune modulation in CKS therapy. Based on favorable responses in viral-induced cancers, we hypothesized that CTLA-4 and PD-1 blockade can induce tumor regression in CKS. We present pre-planned interim analysis of a phase II study of Nivo/Ipi in previously treated progressive CKS (NCT03219671). Methods: CKS pts with progressive disease after ≥ 1 line of systemic therapy and measurable disease by PET/CT and/or physical exam received nivolumab 240mg d1,15,28 and ipilimumab 1mg/kg d1 q42 days until progression or toxicity. The primary endpoint was overall response rate (ORR), secondary endpoints include 6-months progression free survival rate (PFS) and safety. Correlative studies in tumor and serum samples are ongoing using an NGS panel for DNA and RNA and proteomic staining (Tempus Labs Inc). A pre-planned interim analysis was conducted after the first ten enrolled patients for efficacy and toxicity evaluation. Results: Ten patients were enrolled and evaluable between April2018 and February2019. Median age 72 (61-79), all male. At a median FU of 3.1 months (1.5-8.1) ORR was 50% (4 patients PR, 1 patient CR, 5 patients SD). Median PFS was not reached however no progression of disease was documented so far. The safety profile was as expected with all patients experiencing G1 toxicity and four patients with G2 toxicity (1 ALT/AST increase, 2 asymptomatic lipase increase). One SAE was reported (TIA considered not related to therapy) and treatment was discontinued in one patient (G2 LFT increase. maintaining CR 4 months after treatment discontinuation). Correlative results are pending. Conclusions: The interim analysis in this prospectively designed phase II study of nivolumab and low-dose ipilimumab demonstrate promising activity in progressive CKS, with 50% ORR and no events of progression thus far. We expect to report the updated efficacy and correlative data. Clinical trial information: NCT03219671.

Exploring the potential of mucin 13 (MUC13) as a biomarker for carcinomas and other diseases

BACKGROUND

Mucin 13 (MUC13) is a cell surface glycoprotein aberrantly expressed in a variety of epithelial carcinomas. Thus far, the role of MUC13 in various diseases remains elusive. To the best of our knowledge, this is the first study to examine the potential of MUC13 as a serum biomarker in a variety of carcinomas and other conditions.

METHODS

We developed a recombinant MUC13 protein, mouse monoclonal antibodies and enzyme immunoassay (ELISA) for MUC13. We used this assay to measure MUC13 levels in the supernatants of cancer cell lines and a large cohort of serum samples from healthy and diseased individuals.

RESULTS

MUC13 is secreted from cancer cell lines, with highest levels found in ovarian cancer cell lines. MUC13 levels in human sera were significantly increased in patients with renal failure and 20%-30% of patients with ovarian, liver, lung and other cancers. MUC13 was also elevated in 70% of patients with active cutaneous melanoma, but not uveal melanoma. Furthermore, we identified significant MUC13 elevations in the serum of patients with vasculitis (ANCA-positive) autoantibodies, but not in those with inflammatory bowel disease.

CONCLUSIONS

Serum MUC13 is frequently elevated not only in a variety of malignant cases but also in some benign pathologies, thus appearing to be a non-specific disease biomarker. Nonetheless, serum MUC13 is clearly highly elevated in some carcinoma patients, and its relationship with tumor progression in this context warrant further research. Future studies that examine the correlation between serum MUC13 levels to stage of cancer could elucidate prognostic potential.

Potent Activation of Human T Cells by mRNA Encoding Constitutively Active CD40

New strategies for augmenting the actual performance of therapeutic T cells in vivo are needed for improving clinical outcome of adoptive cell therapy. Cumulative findings suggest that CD40 plays an intrinsic role in T cell costimulation. Recently, we demonstrated the ability of truncated, auto-oligomerizing CD40 derivatives to induce strong activation of APCs in a ligand-independent manner. We reasoned that constitutively active CD40 (caCD40) can similarly exert enhancing effects on human antitumor T cells. To test this assumption, we transfected human T cells with in vitro-transcribed caCD40 mRNA. In polyclonal T cells, caCD40 triggered IFN-γ secretion and upregulated CD25 and 4-1BB. In antimelanoma tumor-infiltrating lymphocytes (TILs), caCD40 induced massive production of IFN-γ, exerting a pronounced synergistic effect when coexpressed with constitutively active TLR4 devoid of its extracellular ligand binding. In unselected "young" TILs, caCD40 reproducibly increased surface expression of CD25, OX40, 4-1BB, CD127, and CD28. Three days post-mRNA electroporation of CD8 TILs, caCD40 elevated IFN-γ and TNF-α production and cytolytic activity in the presence of autologous but not HLA-I-mismatched melanoma. Enhanced killing of autologous melanoma by young TILs was observed 4 d posttransfection. These findings suggest that caCD40 can function as a potent T cell adjuvant and provide essential guidelines for similar manipulation of other key members of the TNFR family.

Combined Analysis of Antigen Presentation and T-cell Recognition Reveals Restricted Immune Responses in Melanoma

The quest for tumor-associated antigens (TAA) and neoantigens is a major focus of cancer immunotherapy. Here, we combine a neoantigen prediction pipeline and human leukocyte antigen (HLA) peptidomics to identify TAAs and neoantigens in 16 tumors derived from seven patients with melanoma and characterize their interactions with their tumor-infiltrating lymphocytes (TIL). Our investigation of the antigenic and T-cell landscapes encompassing the TAA and neoantigen signatures, their immune reactivity, and their corresponding T-cell identities provides the first comprehensive analysis of cancer cell T-cell cosignatures, allowing us to discover remarkable antigenic and TIL similarities between metastases from the same patient. Furthermore, we reveal that two neoantigen-specific clonotypes killed 90% of autologous melanoma cells, both in vitro and in vivo, showing that a limited set of neoantigen-specific T cells may play a central role in melanoma tumor rejection. Our findings indicate that combining HLA peptidomics with neoantigen predictions allows robust identification of targetable neoantigens, which could successfully guide personalized cancer immunotherapies.Significance: As neoantigen targeting is becoming more established as a powerful therapeutic approach, investigating these molecules has taken center stage. Here, we show that a limited set of neoantigen-specific T cells mediates tumor rejection, suggesting that identifying just a few antigens and their corresponding T-cell clones could guide personalized immunotherapy. Cancer Discov; 8(11); 1366-75. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1333.