Peripheral T-Cell Priming and Micrometastatic Disease Control with Metastasis-Directed Therapy: Multidimensional Immunogenomic Profiling of Oligometastatic Prostate Cancer in the EXTEND Trial

PURPOSE/OBJECTIVE(S)

Comprehensive metastasis-directed therapy (MDT) for oligometastatic prostate cancer extended progression-free survival (PFS) and time to new lesion formation in the intermittent hormone therapy (HT) basket of EXTEND. To better understand the mechanism of MDT benefit, we pooled the intermittent and continuous HT baskets of EXTEND and tested the hypothesis that adding MDT to HT would program systemic T-cells to control micrometastatic disease.

MATERIALS/METHODS

A total of 174 men were randomized to HT with or without MDT to up to 5 sites of metastases. HT was given for 6 months (intermittent basket, n = 87) or indefinitely (continuous basket, n = 87). Peripheral blood samples were drawn at enrollment, at the end of MDT, at 3 months follow-up (3 mo F/U), and at progression and then analyzed by flow cytometry, T-cell receptor (TCR)-β CDR3 variable region sequencing, multiplex cytokine profiling, and next-generation circulating tumor DNA (ctDNA) sequencing. TCR clonal expansion was determined using a published betabinomial model. Repertoire changes were assessed by Morisita's index, and dominant TCR repertoire motifs were characterized with ImmunoMap. Associations between blood markers and PFS were evaluated with Cox regression adjusted hazard ratios (aHR) accounting for randomization arm and stratifying for intermittent vs continuous HT.

RESULTS

Randomization to MDT+HT was associated with T-cell activation, proliferation, and clonal expansion. This response was first observed at end-MDT as upregulated expression of T-cell activation and inhibition markers (i.e., ICOS, Tim-3, and LAG-3) and increases in highly proliferative CD4+ and CD8+ Ki67hi T-cells (all P<0.05). TCR sequencing of 7,678,911 T-cells revealed that MDT+HT was associated with TCR clonal expansion, remodeling of the TCR repertoire, and changes in dominant TCR motifs at end-MDT and 3 mo F/U (all P<0.05). Observed T-cell priming could be driven by signaling networks of canonical T-cell stimulatory cytokines (IL-2, IL-12, and IL-15), which were upregulated at end-MDT and persisted at 3 mo F/U (all P<0.05). This modulation of T-cell phenotype, clonotype, and cytokine concentrations was not observed in the HT-monotherapy arm. At end-MDT, systemic T-cell responses were associated with improved PFS, most notably CD8+ T-cell expression of LAG-3 (aHR 0.22, 95% CI 0.03-0.91) and high TCR clonal expansion (aHR 0.13, 95% CI 0.02-0.52). High ctDNA burden at end-MDT correlated with worse PFS (aHR 1.41, 95% CI 1.04-2.54), as did CD8+ T-cell expression of inhibitory receptor TIGIT at 3 mo F/U (aHR 1.03, 95% CI 1.01-1.06).

CONCLUSION

The addition of MDT to HT induced systemic T-cell activation and expansion, which was not observed in the HT-only arm. This systemic immune response was independently associated with improved PFS. In addition to cytoreduction of macroscopic disease, MDT-induced immune education may be an important complementary mechanism of micrometastatic control in oligometastatic prostate cancer.

Distinct tumor-infiltrating lymphocyte landscapes are associated with clinical outcomes in localized non-small-cell lung cancer

BACKGROUND

Despite the importance of tumor-infiltrating T lymphocytes (TILs) in cancer biology, the relationship between TIL phenotypes and their prognostic relevance for localized non-small-cell lung cancer (NSCLC) has not been well established.

PATIENTS AND METHODS

Fresh tumor and normal adjacent tissue was prospectively collected from 150 patients with localized NSCLC. Tissue was comprehensively characterized by high-dimensional flow cytometry of TILs integrated with immunogenomic data from multiplex immunofluorescence, T-cell receptor sequencing, exome sequencing, RNA sequencing, targeted proteomics, and clinicopathologic features.

RESULTS

While neither the magnitude of TIL infiltration nor specific TIL subsets were significantly prognostic alone, the integration of high-dimensional flow cytometry data identified two major immunotypes (IM1 and IM2) that were predictive of recurrence-free survival independent of clinical characteristics. IM2 was associated with poor prognosis and characterized by the presence of proliferating TILs expressing cluster of differentiation 103, programmed cell death protein 1, T-cell immunoglobulin and mucin-domain containing protein 3, and inducible T-cell costimulator. Conversely, IM1 was associated with good prognosis and differentiated by an abundance of CD8⁺ T cells expressing cytolytic enzymes, CD4⁺ T cells lacking the expression of inhibitory receptors, and increased levels of B-cell infiltrates and tertiary lymphoid structures. While increased B-cell infiltration was associated with good prognosis, the best prognosis was observed in patients with tumors exhibiting high levels of both B cells and T cells. These findings were validated in patient tumors from The Cancer Genome Atlas.

CONCLUSIONS

Our study suggests that although the number of infiltrating T cells is not associated with patient survival, the nature of the infiltrating T cells, resolved in distinct TIL immunotypes, is prognostically relevant in NSCLC and may inform therapeutic approaches to clinical care.

Liquid biopsy assay for lung carcinoma using centrifuged supernatants from fine-needle aspiration specimens

INTRODUCTION

Tumor mutation profiling is standard-of-care in lung carcinoma patients. However, comprehensive molecular profiling of small specimens, including core needle biopsy (CNB) and fine-needle aspiration (FNA) specimens, may often be inadequate due to limited tissue. Centrifuged FNA supernatants, which are typically discarded, have emerged recently as a novel liquid-based biopsy for molecular testing. In this study, we evaluate the use of lung carcinoma FNA supernatants for detecting clinically relevant mutations.

METHODS

Supernatants from lung carcinoma FNA samples (n = 150) were evaluated. Samples were further analyzed using next-generation sequencing (NGS) and ultrasensitive droplet digital PCR (ddPCR). Mutation profiles in a subset of samples were compared with results derived from paired tissue samples from the same patient (n = 67) and available plasma liquid biopsy assay (n = 45).

RESULTS

All 150 samples yielded adequate DNA and NGS were carried out successfully on 104 (90%) of 116 selected samples. Somatic mutations were detected in 82% of the samples and in 50% of these patients a clinically relevant mutation was identified that would qualify them for targeted therapy or a clinical trial. There was high overall concordance between the mutation profiles of supernatants and the corresponding tissue samples, with 100% concordance with concurrent FNA and 96% with concurrent CNB samples. Comparison of actionable driver mutations detected in supernatant versus plasma samples showed 84% concordance.

CONCLUSIONS

FNA supernatants can provide a valuable specimen source for genotyping lung carcinoma especially in patients with insufficient tumor tissue, thereby reducing multigene mutation profiling failure rates, improving turnaround times, and avoiding repeat biopsies.

Abstract OT3-05-04: Phase II study of atezolizumab, cobimetinib, and eribulin in patients with recurrent or metastatic inflammatory breast cancer (IBC)

Background: IBCs that do not completely respond to chemotherapy often have dysregulated immune pathways, and novel therapies are needed to improve outcomes in recurrent/metastatic disease. One-third of IBCs express the atezolizumab target PD-L1, and cobimetinib increases PD-L1 expression; thus, we hypothesize that atezolizumab and cobimetinib may act synergistically in IBC. The FDA-approved agent eribulin is active in IBC and has anti-stem cell activity and can reverse the IBC phenotype of epithelial-to-mesenchymal transition. Hence the use of eribulin as a chemotherapy backbone in combination with other novel agents is well justified.

Trial Design: This single-arm, open-label trial is enrolling patients with recurrent IBC or de novo metastatic IBC that has progressed on at least 1 line of standard chemotherapy. During a 4-week pharmacodynamic window, patients have an upfront biopsy, receive atezolizumab and cobimetinib treatment for 4 weeks, and have a second biopsy. Triple-combination treatment then commences, with standard eribulin dosing. After 4 cycles of eribulin, patients receive maintenance targeted therapy until disease progression or intolerable toxicity.

Eligibility Criteria: Patients with metastatic IBC of any molecular subtype must have measurable disease (per RECIST 1.1) amenable to biopsy. Patients with HER2+ disease must have received both pertuzumab and T-DM1. Patients with treated stable brain metastases are allowed. Patients must have recovered from the acute effects of any prior therapies and have adequate hematologic, organ, and cardiac function. Patients with autoimmune diseases or a history of pneumonitis are ineligible.

Specific Aims: The primary objective is to determine the overall response rate (ORR) of the combination therapy. Secondary objectives include determining the safety and tolerability, clinical benefit rate, response duration, progression-free survival, 2-year overall survival rate and predictive biomarker analyses.

Statistical Methods: The trial will enroll up to 9 patients in its phase I/safety lead-in portion and up to 33 patients total. A Bayesian optimal interval design is used to efficiently determine the maximum tolerated cobimetinib dose in phase I. Patients start cobimetinib at the FDA-approved dose of 60 mg/day with a target toxicity rate is 0.3. Phase II will enroll 24 patients to determine the efficacy of the triple-combination therapy. The historical ORR in metastatic IBC is 10%; our sample size provides 80% power to detect an ORR improvement to 25%.

Accrual: The trial has enrolled 7 patients since its start in August 2017.

Citation Format: Alexander A, Marx AN, Reddy SM, Reuben JM, Le-Petross HC, Lane D, Huang ML, Krishnamurthy S, Gong Y, Gombos DS, Patel N, Tung CI, Allen RC, Kandl TJ, Wu J, Liu S, Patel AB, Futreal A, Wistuba I, Layman RM, Valero V, Tripathy D, Ueno NT, Lim B. Phase II study of atezolizumab, cobimetinib, and eribulin in patients with recurrent or metastatic inflammatory breast cancer (IBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-05-04.