Evaluating T-cell cross-reactivity between tumors and immune-related adverse events with TCR sequencing: pitfalls in interpretations of functional relevance

T-cell receptor sequencing (TCRseq) enables tracking of T-cell clonotypes recognizing the same antigen over time and across biological compartments. TCRseq has been used to test if cross-reactive antitumor T cells are responsible for development of immune-related adverse events (irAEs) following immune checkpoint blockade. Prior studies have interpreted T-cell clones shared among the tumor and irAE as evidence supporting this, but interpretations of these findings are challenging, given the constraints of TCRseq. Here we capitalize on a rare opportunity to understand the impact of potential confounders, such as sample size, tissue compartment, and collection batch/timepoint, on the relative proportion of shared T-cell clones between an irAE and tumor specimens. TCRseq was performed on tumor-involved and -uninvolved tissues, including an irAE, that were obtained throughout disease progression and at the time of rapid autopsy from a patient with renal cell carcinoma treated with programmed death-1 (PD-1) blockade. Our analyses show significant effects of these confounders on our ability to understand T-cell receptor overlap, and we present mitigation strategies and study design recommendations to reduce these errors. Implementation of these strategies will enable more rigorous TCRseq-based studies of immune responses in human tissues, particularly as they relate to antitumor T-cell cross-reactivity in irAEs following checkpoint blockade.

Trial in progress: Neoadjuvant immune checkpoint blockade in resectable malignant pleural mesothelioma

TPS9078

Background: While the role of surgery in limited-stage (stage I-III) malignant pleural mesothelioma (MPM) is controversial, many centers have adopted an aggressive tri-modality approach incorporating (neo)adjuvant chemotherapy, surgical resection and radiotherapy. Despite this, most patients relapse and die from their disease. Immune checkpoint blockade (ICB) has shown promise in advanced MPM, but the mechanisms of response and resistance remain elusive. Improving the mechanistic understanding of ICB in MPM while concurrently optimizing the treatment strategy for limited-stage MPM are two urgent unmet needs. This multicenter multi-arm phase I/II study seeks to evaluate the safety and feasibility of neoadjuvant ICB in resectable MPM, incorporating novel genomic and immunologic analyses to deliver mechanistic insight into the biology of ICB in MPM. Methods: Patients with surgically resectable stage I-III treatment-naïve epithelioid or biphasic MPM receive neoadjuvant treatment with nivolumab every 2 weeks for 3 doses with or without 1 dose of ipilimumab (arm A: nivolumab monotherapy; arm B: nivolumab + ipilimumab). After macroscopic complete resection, patients receive optional investigator-choice adjuvant chemotherapy +/- radiation. Following this, patients will receive up to 1 year of adjuvant nivolumab. Feasibility and safety are co-primary endpoints of this study with feasibility defined by a delay in surgery of ≤24 days from the preplanned surgical date and safety defined by adverse events according to CTCAE v5.0. Bayesian-designed stopping rules have been implemented for feasibility and safety. Secondary endpoints include assessment of pathologic response and radiographic response using RECIST 1.1 for MPM. Correlative analyses will be performed on tissue specimens obtained pre- and post-ICB, as well as blood obtained pre, during, and post-ICB. Key correlates include multiplex immunofluorescence and longitudinal ctDNA assessment. Whole exome sequencing, T-cell receptor sequencing, and the MANAFEST functional neoantigen assay will be utilized to identify neoantigen-specific T-cell clonotypes and track these clonotypes temporally (during/post ICB) and spatially (across immune compartments). Single-cell RNA sequencing will be used to characterize the functionality of expanded T-cell clonotypes. Accrual to arm B will commence following complete accrual to arm A with a planned total enrollment of 30 patients. This study is open with 1 patient enrolled at the time of submission. Clinical trial information: NCT03918252.

PD-L1 and Emerging Biomarkers in Immune Checkpoint Blockade Therapy

PD-L1 checkpoint blockade is revolutionizing cancer therapy, and biomarkers capable of predicting which patients are most likely to respond are highly desired. The detection of PD-L1 protein expression by immunohistochemistry can enrich for response to anti-PD-(L)1 blockade in a variety of tumor types, but is not absolute. Limitations of current commercial PD-L1 immunohistochemical (IHC) assays and improvements anticipated in next-generation PD-L1 testing are reviewed. Assessment of tumor-infiltrating lymphocytes in conjunction with PD-L1 testing could improve specificity by distinguishing adaptive (interferon γ driven and cytotoxic T-lymphocyte associated) from constitutive (non-immune mediated) expression. The presence of a high tumor mutational burden also enriches for response to therapy, and early data indicate that this may provide additive predictive value beyond PD-L1 IHC alone. As candidate biomarkers continue to emerge, the pathologist's assessment of the tumor microenvironment on hematoxylin-eosin stain combined with PD-L1 IHC remains a rapid and robust way to evaluate the tumor-immune dynamic.

Neoadjuvant nivolumab in early-stage, resectable non-small cell lung cancers

8508

Background: Anti-PD-1 therapy produces objective and often durable responses in ~20% of unselected patients (pts) with metastatic non-small cell lung cancer (NSCLC). However, the role of PD-1 blockade in treating resectable NSCLC is unknown. This is the first study to test nivolumab in the neoadjuvant setting. This trial design provides an opportunity to examine anti-PD-1 mechanism of action and immunologic correlates of outcomes. Methods: Patients with Stage IB - IIIA NSCLC received 2 doses of nivolumab 3mg/kg over 4 weeks before surgery. The primary endpoint was safety in 20 patients with resected NSCLC. Efficacy was explored using objective pathologic response criteria. Correlative studies of the tumor immune microenvironment, tumor mutation and predicted neoantigen loads, and changes in T cell receptor (TCR) clonality in tumor and blood pre and post treatment were conducted. Results: 22 pts were treated. Nivolumab was well-tolerated and no surgeries were delayed. 1 pt withdrew from study preop without progression or toxicity. Among the 21 attempted resections, 1 tumor was unresectable. 9/21 (43%, 95% CI 24-63%) had a major pathologic response ( < 10% viable tumor cells in resection specimen). With a median postop follow-up of 9 months, 18 pts (86%) remain alive and recurrence free. Pre-treatment tumor exome sequencing showed a correlation between both tumor mutation and predicted neoantigen loads with pathologic response. Multiplex immunohistochemistry of pre- and post-treatment tumors showed an influx of PD-1+CD8+ T cells into responding tumors. TCR sequencing demonstrated that expanded peripheral T cell clones after treatment match clones found in the tumor. Conclusions: Neoadjuvant nivolumab in resectable NSCLC did not delay surgery. Major pathologic response rate was encouraging and compares favorably to outcomes with cisplatin-based neoadjuvant chemotherapy. Genomic analyses suggest that higher mutational and neoantigen burden could result in deeper pathologic response. Immunologic analyses support the detection of intra-tumoral T cell clones in the blood after treatment with nivolumab and may provide further insight into the molecular and immunologic features of response and non-response to PD-1 blockade. Clinical trial information: NCT02259621.

Reliability and validity of the velotron racermate cycle ergometer to measure anaerobic power

This study assessed the reliability and validity of the Velotron Racermate™ cycle ergometer to assess anaerobic power. Men (9 cyclists and 13 recreationally-active) and women (17 recreationally-active and 1 cyclist) (age=24.7±4.2 yr) performed 2 Wingate tests on the Velotron or 3 Wingate tests (2 on the Velotron and 1 on the Monark Peak Bike) over a 7-14 day period. Peak power, mean power, minimum power, fatigue index, heart rate, and peak and minimum cadence were assessed. Results revealed significant test-retest reliability for mean power (r=0.90, p<0.01), minimum power (r=0.79, p<0.05) and peak power (r=0.70, p<0.05) with repeated bouts on the Velotron. Peak power was significantly higher (p<0.05) on the Velotron (9.95±1.39 W/kg) vs. the Monark (9.13±1.26 W/kg); however, mean power was higher (p<0.05) on the Monark (6.95±0.89 W/kg) vs. the Velotron (6.11±0.52 W/kg and 6.25±0.59 W/kg). Data reveal significant reliability for mean and peak power from the Velotron Racermate, yet multiple variables differ between the Velotron and the Monark mechanically-braked cycle ergometer.

Volatile components of roots, stems, leaves, and flowers of Echinacea species

The headspace volatile components of roots, stems, leaves, and flowers of Echinacea angustifolia,E. pallida, and E. purpurea were analyzed by capillary gas chromatography/mass spectrometry (GC/MS). Over 70 compounds were identified in the samples. All plant tissues, irrespective of the species, contain acetaldehyde, dimethyl sulfide, camphene, hexanal, beta-pinene, and limonene. The main headspace constituents of the aerial parts of the plant are beta-myrcene, alpha-pinene, limonene, camphene, beta-pinene, trans-ocimene, 3-hexen-1-ol, and 2-methyl-4-pentenal. The major headspace components of root tissue are alpha-phellandrene (present only in the roots of E. purpurea and E.angustifolia), dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, 2-methylpropanal, acetaldehyde, camphene, 2-propanal, and limonene. Aldehydes, particularly butanals and propanals, make up 41-57% of the headspace of root tissue, 19-29% of the headspace of the leaf tissue, and only 6-14% of the headspace of flower and stem tissues. Terpenoids including alpha- and beta-pinene, beta-myrcene, ocimene, limonene, camphene, and terpinene make up 81-91% of the headspace of flowers and stems, 46-58% of the headspace of the leaf tissue, and only 6-21% of the roots. Of the 70 compounds identified, >50 are reported in Echinacea for the first time.

Solving the complementarity dilemma: evolving strategies for simultaneous hermaphroditism

We introduce a complementarity dilemma, a two-player, binary response game in which the playoffs are highest when the two players respond differently. Using the classifier EvA, we determine the evolutionary dynamics and structure of strategies that evolve to play an iterated version of this game, and we relate the results to the evolution of major types of sexual reproduction, particularly simultaneous hermaphroditism. We find that complementarity strategies consistently evolve under a broad range of conditions, but that those most consistent with the simultaneous hermaphroditism can predominate only when a substantial cost of repeatedly adopting the female role is imposed. The cost is analogous to the fecundity reduction to be expected when a single partner must repeatedly produce the eggs in sexual reproduction.