601 Sequencing immunotherapy before lymphatic ablation unleashes cDC1-dependent antitumor immunity in HNSCC

Background

Despite the proven efficacy of immune checkpoint inhibitor (ICI) therapy in the recurrent/metastatic setting for head and neck squamous cell carcinoma (HNSCC), clinical trials of ICI combined with curative-intent therapies have yielded equivocal results [1–4]. Collectively, this highlights gaps in our understanding of rational immune oncology (IO) treatment sequencing and suggests that the efficacy ICI may be disrupted by standard therapies, which necessarily compromise regional lymphatics.

Methods

We employ a preclinical model of tobacco-signature HNSCC to identify sequences of therapy that maximize durable response. By mapping the cervical lymphatic basins in the mouse, we define patterns of active antitumor immunosurveillance. Additionally, we establish tumors with distinct patterns of regional lymphatic drainage and develop a murine neck dissection (ND) model.

Results

We find that cervical lymphatic ablation, with ND or stereotactic body radiation therapy, in tumor bearing animals abolishes the response to ICI therapy, significantly impacting overall survival. Examination of the tumor immune microenvironment following ND reveals dramatic changes with a ten-fold increase in CD45 cells and exclusion of cytotoxic and antigen-specific lymphocytes. By examining the lymphatics removed at the time of ND, we find that conventional type I dendritic cells (cDC1s) and type I interferon (IFN-I) signaling are significantly increased, suggesting that these effectors are lost after curative-intent therapy. Depleting IFN-I or cDC1s blocks the response to ICI similar to lymphatic ablation. We find that successful primary response to ICI leads to durable immunity, conferred by systemically distributed memory T cells, not impaired by delayed ND. Lastly, we discover a rational IO treatment sequence by delivering neoadjuvant ICI followed by ND. Neoadjuvant ICI leads to complete tumor response, accumulation of nodal cDC1, and durable immunity. Surprisingly, the incidence of nodal metastasis at early timepoints reveals a similar burden of nodal disease between control and ICI-treated animals that decreases at late timepoints only with ICI treatment (44% vs 15%, n=25, p=0.033). This suggests that ICI also drives active immunosurveillance in regional, tumor-draining lymphatics, challenging the landmark findings from the definitive clinical trial demonstrating the benefit of elective versus therapeutic neck dissection for oral SCC patients with clinically negative necks.

Conclusions

This work demonstrates the necessity of preserving tumor-draining lymphatics during the tumor response to ICI therapy in HNSCC. Overall, we define rational IO treatment sequences to achieve optimal primary tumor response, durable antitumor immunity and immunosurveillance of regional metastatic disease. These findings can inform future clinical trials investigating combination IO therapy and treatment sequencing.

References

Harrington, K. J. et al. Nivolumab versus standard, single-agent therapy of investigator’s choice in recurrent or metastatic squamous cell carcinoma of the head and neck (CheckMate 141): health-related quality-of-life results from a randomised, phase 3 trial. Lancet Oncology 18, 1104–1115 (2017).

Burtness, B. et al. Pembrolizumab alone or with chemotherapy versus cetuximab with chemotherapy for recurrent or metastatic squamous cell carcinoma of the head and neck (KEYNOTE-048): a randomised, open-label, phase 3 study. Lancet (London, England) 394, 1915–1928 (2019).

Lee, N. Y. et al. Avelumab plus standard-of-care chemoradiotherapy versus chemoradiotherapy alone in patients with locally advanced squamous cell carcinoma of the head and neck: a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial. Lancet Oncol 22, 450–462 (2021).

D’Cruz, A. K. et al. Elective versus Therapeutic Neck Dissection in Node-Negative Oral Cancer. New England Journal of Medicine 373, 521–529 (2015).

433 A phase 2 study of evorpacept (ALX148) in combination with pembrolizumab and chemotherapy in patients with advanced head and neck squamous cell carcinoma (HNSCC); ASPEN-04

Background

Anticancer immunity relies on the release of tumor antigens and subsequent activation of the innate and adaptive immune systems. After cytotoxic chemotherapy induces neoantigen release, myeloid checkpoint inhibitors can help potentiate innate immune cell activity including antigen presentation. CD47 is a marker of self that interacts with SIRPα on myeloid immune cells and is upregulated by tumors to evade immune responses. Evorpacept is a high affinity CD47-blocking fusion protein with an inactive Fc region designed to safely enhance standard anticancer therapeutics. Pembrolizumab, a T cell checkpoint inhibitor that activates cytotoxic lymphocytes, is a standard option for patients with previously untreated recurrent/metastatic (R/M) HNSCC, both as a monotherapy and in combination with 5FU + platinum. Through increased activation of the immune system, a combination of evorpacept + pembrolizumab + 5FU/platinum might have more anti-tumor activity in R/M HNSCC than current standard therapeutic approaches. This combination approach could be particularly beneficial to R/M HNSCC patients with low PD-L1 expression, where anti-PD-(L)1 therapy historically has diminished efficacy. The combination of evorpacept + pembrolizumab + 5FU/platinum has undergone preliminary testing in the ongoing Phase 1 ASPEN-01 study,1 demonstrating initial clinical response and tolerability. In previously untreated, PD-L1-unselected R/M HNSCC patients treated with evorpacept + pembrolizumab + 5FU/platinum, patients experienced objective responses, including complete response. The ASPEN-04 study will assess the efficacy and safety of evorpacept in combination with pembrolizumab and chemotherapy in previously untreated patients with PD-L1-unselected R/M HNSCC.

Methods

ASPEN-04 (figure 1) is an ongoing non-comparative, open-label, randomized Phase 2 global study of evorpacept + pembrolizumab + chemotherapy (5FU + either carboplatin or cisplatin) or pembrolizumab + chemotherapy in patients with PD-L1-unselected metastatic or unresectable recurrent HNSCC who have not yet been treated for their advanced disease. After an initial safety lead-in cohort, ~106 patients will be randomized to receive evorpacept + pembrolizumab + chemotherapy or pembrolizumab + chemotherapy. Minimization factors used to randomize patients include geography, PD-L1 combined positive score, and HPV (p16) status. Patients in the evorpacept treatment arm will receive evorpacept 45 mg/kg IV Q3W. All patients will receive pembrolizumab 200 mg IV Q3W (maximum of 35 cycles) and standard administration of 5FU and platinum agents. The primary endpoint in this Simon two-stage trial design is objective response rate using RECIST v1.1. Key secondary endpoints include duration of response, progression-free survival, overall survival, and safety. Exploratory endpoints will characterize pharmacodynamic properties.

Abstract 433 Figure 1

ASPEN-04 Study Schema

Acknowledgements

We would like to thank all the participating patients, their families, and site research teams.

Trial Registration

ClinicalTrials.

gov identifier, NCT04675333

References

Keun-Wook Lee, Hyun Cheol Chung, Won Seog Kim, et al. ALX148, a CD47 blocker, in combination with standard chemotherapy and antibody regimens in patients with gastric/gastroesophageal junction (GC) cancer and head and neck squamous cell carcinoma (HNSCC); ASPEN-01. Poster presented at: Society for Immunotherapy of Cancer Annual Meeting; November 2020.

Ethics Approval

The study was approved by all participating institutions’ Ethics and/or Review Boards.

523 Preliminary clinical experience with XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

Background

XmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report updated data on patients treated at the recommended expansion dose from an ongoing, multicenter, Phase 1, dose-escalation and -expansion study of intravenous XmAb20717 in patients with selected advanced solid tumors that progressed after treatment with all standard therapies or with no standard therapeutic options.

Methods

A maximum tolerated dose was not reached in dose escalation. XmAb20717 10 mg/kg every 2 weeks (Q2W) was selected as the expansion dose, based on consistent T-cell proliferation in peripheral blood indicative of dual PD-1/CTLA-4 checkpoint blockade, and response to treatment (RECIST[1.1]).1 Parallel expansion cohorts included ~20 patients each with melanoma, renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), castration-resistant prostate cancer (CRPC), and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI). Patients treated with 10 mg/kg in dose escalation were pooled with expansion cohorts for analysis of clinical activity and safety.

Results

As of 9 June 2021, 110 patients, ranging in age from 39 to 89 years and 66.4% male, were treated, and 5 were continuing treatment. Patients had received a median of 4 prior systemic treatment regimens, including CI therapy for 64.5%. The objective response rate was 13.0% (10/77 patients evaluable for efficacy), including 1 complete response (melanoma [confirmed]) and 9 partial responses (confirmed: 1 melanoma, 2 RCC, 2 CRPC, 1 ovarian cancer; unconfirmed: 1 melanoma, 2 NSCLC). The CRPC responders (2/7 with RECIST-measurable disease) had confirmed PSA decreases ≥ 50% from baseline (to 0.02 and 0.3 ng/mL); neither had progression on bone scans. All responders had prior CI exposure, except those with CRPC. Robust CD4 and CD8 T-cell activation was seen. Low baseline tumoral expression of myeloid recruitment genes, including IL-8, was associated with clinical benefit. Grade ≥ 3 immunotherapy-related adverse events in ≥ 3 patients included rash (16.4%), transaminase elevations (9.1%), hyperglycemia (4.5%), acute kidney injury (3.6%), amylase and lipase increased (2.7%), and lipase increased (2.7%).

Conclusions

Preliminary data indicate 10 mg/kg XmAb20717 Q2W was associated with complete and partial responses in multiple tumor types and was generally well-tolerated in these heavily pretreated patients with advanced cancer. Changes in T-cell populations in the periphery and tumor are consistent with robust dual checkpoint blockade. These findings support further development of XmAb20717 in advanced solid tumors, including metastatic prostate cancer.

Trial Registration

NCT03517488

References

Shum E, Daud A, Reilley M, et al. Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors. JITC 2020;8(3):A247-8.

Ethics Approval

The study was approved by each institution’s IRB.

Multisystem Inflammatory Syndrome in an Adult With COVID-19-A Trial of Anakinra: A Case Report

COVID-19 disease has been a pandemic caused by a β-coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A life-threatening multisystem inflammatory syndrome (MIS), secondary to SARS-CoV-2 virus infection, sharing common features with Kawasaki disease shock syndrome, staphylococcal/streptococcal shock syndrome, and macrophage activation syndrome in pediatric patients has been described. A total of 27 cases in adults (MIS-A) with a similar presentation have been reported so far. Here we describe the case of a 21-year-old man admitted with abdominal pain, diarrhea, tachycardia, and low blood pressure. He had elevated troponin, ferritin, and interleukin-2 receptor levels and had evidence of myocarditis. He tested positive for SARS-CoV-2 IgG antibody, and a diagnosis of MIS-A was made. Our case adds to the scant literature on this topic, and to our knowledge, it is the first case where anakinra was administered. He recovered well. MIS-A should be considered when young adults present with multiorgan dysfunction.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

The Cancer Epitope Database and Analysis Resource: A Blueprint for the Establishment of a New Bioinformatics Resource for Use by the Cancer Immunology Community

Recent years have witnessed a dramatic rise in interest towards cancer epitopes in general and particularly neoepitopes, antigens that are encoded by somatic mutations that arise as a consequence of tumorigenesis. There is also an interest in the specific T cell and B cell receptors recognizing these epitopes, as they have therapeutic applications. They can also aid in basic studies to infer the specificity of T cells or B cells characterized in bulk and single-cell sequencing data. The resurgence of interest in T cell and B cell epitopes emphasizes the need to catalog all cancer epitope-related data linked to the biological, immunological, and clinical contexts, and most importantly, making this information freely available to the scientific community in a user-friendly format. In parallel, there is also a need to develop resources for epitope prediction and analysis tools that provide researchers access to predictive strategies and provide objective evaluations of their performance. For example, such tools should enable researchers to identify epitopes that can be effectively used for immunotherapy or in defining biomarkers to predict the outcome of checkpoint blockade therapies. We present here a detailed vision, blueprint, and work plan for the development of a new resource, the Cancer Epitope Database and Analysis Resource (CEDAR). CEDAR will provide a freely accessible, comprehensive collection of cancer epitope and receptor data curated from the literature and provide easily accessible epitope and T cell/B cell target prediction and analysis tools. The curated cancer epitope data will provide a transparent benchmark dataset that can be used to assess how well prediction tools perform and to develop new prediction tools relevant to the cancer research community.

Abstract CT134: A phase I study of avelumab, palbociclib, and cetuximab (APC) in recurrent or metastatic head and neck squamous cell carcinoma (RM HNSCC)

Background: Checkpoint inhibitors have activity in RM HNSCC, but response rates to single agent therapy are low. Combination therapy may improve outcomes. We aimed to study a novel combination of palbociclib (P) and cetuximab (C) with the PD-L1 inhibitor avelumab (A) in RM HNSCC. Methods: Eligible patients (pts) with RM HNSCC received P in combination with A 10 mg/kg IV every 2 wks and C 400 mg/m2 IV x 1, then 250 mg/m2 weekly. The starting dose of P was 75 mg PO daily on days 1 to 21 of a 28 day cycle. The 3+3 dose escalation design included planned doses of P 100 mg and P 125 mg, with no intra-patient escalation. The primary objective was to identify the recommended phase II dose (RP2D); secondary objectives included response rate and progression free survival (PFS). Results: As of 10/15/20, 12 pts have been treated in 3 cohorts: P 75 mg PO daily (3 pts), 100 mg PO daily (3 pts), and 125 mg PO daily (6 pts). Median age was 56 yo, 92% were male, with 58% p16+, 25% p16-, 17% p16 unknown. One DLT was observed in cohort 3: a grade 3 infusion reaction related to C. The RP2D was P 125 mg, with A and C at standard doses. Other grade 3 AEs were leukopenia (4 pts), neutropenia (4 pts), acneiform rash (2 pts), cellulitis (1pt), increased WBC (1pt). One pt had grade 4 leukopenia. There were no grade 5 AEs. Tx related AEs occurring in > 30% of pts were: acneiform rash (11pts), fatigue (10pts), mucositis (7pts), dry skin (6 pts), decreased WBCs (5 pts), paronychia (5 pts), nausea (5pts), hypomagnesemia (4pts). Response rate by RECIST 1.1 was 42% (3 CRs, 2PRs); median duration of response has not been reached. Median PFS was 6.5 m. Reasons for discontinuation were disease progression (8 pts), pt choice (1 pt). 3 patients remain on therapy (after 20, 15, and 9 months). Conclusions: The combination of APC was well tolerated in patients with RM HNSCC; no unexpected toxicities were seen. The RP2D is A 10 mg/kg every 2 wks, C 400 mg/m2 x 1 then 250 mg/m2 wkly, and P 125 mg daily, 3 wks on, one wk off. Promising response rates were seen, and several pts have had durable responses. These data support further development of this combination. Biomarker analyses on tissue and blood are ongoing. NCT03498378.

Citation Format: Kathryn A. Gold, Assuntina Sacco, Julie Bykowski, Gregory Daniels, Emily Pittman, Karen Messer, Ruifeng Chen, Ezra Cohen. A phase I study of avelumab, palbociclib, and cetuximab (APC) in recurrent or metastatic head and neck squamous cell carcinoma (RM HNSCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT134.

Avelumab plus standard-of-care chemoradiotherapy versus chemoradiotherapy alone in patients with locally advanced squamous cell carcinoma of the head and neck: a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial

BACKGROUND

Chemoradiotherapy is the standard of care for unresected locally advanced squamous cell carcinoma of the head and neck. We aimed to assess if addition of avelumab (anti-PD-L1) to chemoradiotherapy could improve treatment outcomes for this patient population.

METHODS

In this randomised, double-blind, placebo-controlled, phase 3 study, patients were recruited from 196 hospitals and cancer treatment centres in 22 countries. Patients aged 18 years or older, with histologically confirmed, previously untreated, locally advanced squamous cell carcinoma of the oropharynx, hypopharynx, larynx, or oral cavity (unselected for PD-L1 status), an Eastern Cooperative Oncology Group performance status score of 0 or 1, and who could receive chemoradiotherapy were eligible. Patients were randomly assigned (1:1) centrally by means of stratified block randomisation with block size four (stratified by human papillomavirus status, tumour stage, and nodal stage, and done by an interactive response technology system) to receive 10 mg/kg avelumab intravenously every 2 weeks plus chemoradiotherapy (100 mg/m2 cisplatin every 3 weeks plus intensity-modulated radiotherapy with standard fractionation of 70 Gy [35 fractions during 7 weeks]; avelumab group) or placebo plus chemoradiotherapy (placebo group). This was preceded by a single 10 mg/kg avelumab or placebo lead-in dose given 7 days previously and followed by 10 mg/kg avelumab or placebo every 2 weeks maintenance therapy for up to 12 months. The primary endpoint was progression-free survival by investigator assessment per modified Response Evaluation Criteria in Solid Tumors, version 1.1, in all randomly assigned patients. Adverse events were assessed in patients who received at least one dose of avelumab or placebo. This trial is registered with ClinicalTrials.gov, NCT02952586. Enrolment is no longer ongoing, and the trial has been discontinued.

FINDINGS

Between Dec 12, 2016, and Jan 29, 2019, from 907 patients screened, 697 patients were randomly assigned to the avelumab group (n=350) or the placebo group (n=347). Median follow-up for progression-free survival was 14·6 months (IQR 8·5-19·6) in the avelumab group and 14·8 months (11·6-18·8) in the placebo group. Median progression-free survival was not reached (95% CI 16·9 months-not estimable) in the avelumab group and not reached (23·0 months-not estimable) in the placebo group (stratified hazard ratio 1·21 [95% CI 0·93-1·57] favouring the placebo group; one-sided p=0·92). The most common grade 3 or worse treatment-related adverse events were neutropenia (57 [16%] of 348 patients in the avelumab group vs 52 [15%] of 344 patients in the placebo group), mucosal inflammation (50 [14%] vs 45 [13%]), dysphagia (49 [14%] vs 47 [14%]), and anaemia (41 [12%] vs 44 [13%]). Serious treatment-related adverse events occurred in 124 (36%) patients in the avelumab group and in 109 (32%) patients in the placebo group. Treatment-related deaths occurred in two (1%) patients in the avelumab group (due to general disorders and site conditions, and vascular rupture) and one (<1%) in the placebo group (due to acute respiratory failure).

INTERPRETATION

The primary objective of prolonging progression-free survival with avelumab plus chemoradiotherapy followed by avelumab maintenance in patients with locally advanced squamous cell carcinoma of the head and neck was not met. These findings may help inform the design of future trials investigating the combination of immune checkpoint inhibitors plus CRT.

FUNDING

Pfizer and Merck KGaA, Darmstadt, Germany.

Doctors of chiropractic working with or within integrated healthcare delivery systems: a scoping review protocol

INTRODUCTION

Back and neck pain are the leading causes of disability worldwide. Doctors of chiropractic (DCs) are trained to manage these common conditions and can provide non-pharmacological treatment aligned with international clinical practice guidelines. Although DCs practice in over 90 countries, chiropractic care is rarely available within integrated healthcare delivery systems. A lack of DCs in private practice, particularly in low-income communities, may also limit access to chiropractic care. Improving collaboration between medical providers and community-based DCs, or embedding DCs in medical settings such as hospitals or community health centres, will improve access to evidence-based care for musculoskeletal conditions.

METHODS AND ANALYSES

This scoping review will map studies of DCs working with or within integrated healthcare delivery systems. We will use the recommended six-step approach for scoping reviews. We will search three electronic data bases including Medline, Embase and Web of Science. Two investigators will independently review all titles and abstracts to identify relevant records, screen the full-text articles of potentially admissible records, and systematically extract data from selected articles. We will include studies published in English from 1998 to 2020 describing medical settings that have established formal relationships with community-based DCs (eg, shared medical record) or where DCs practice in medical settings. Data extraction and reporting will be guided by the Proctor Conceptual Model for Implementation Research, which has three domains: clinical intervention, implementation strategies and outcome measurement. Stakeholders from diverse clinical fields will offer feedback on the implications of our findings via a web-based survey.

ETHICS AND DISSEMINATION

Ethics approval will not be obtained for this review of published and publicly accessible data, but will be obtained for the web-based survey. Our results will be disseminated through conference presentations and a peer-reviewed publication. Our findings will inform implementation strategies that support the adoption of chiropractic care within integrated healthcare delivery systems.

Distinct clinical and immunological features of SARS-CoV-2-induced multisystem inflammatory syndrome in children

BACKGROUNDPediatric SARS-CoV-2 infection can be complicated by a dangerous hyperinflammatory condition termed multisystem inflammatory syndrome in children (MIS-C). The clinical and immunologic spectrum of MIS-C and its relationship to other inflammatory conditions of childhood have not been studied in detail.METHODSWe retrospectively studied confirmed cases of MIS-C at our institution from March to June 2020. The clinical characteristics, laboratory studies, and treatment response were collected. Data were compared with historic cohorts of Kawasaki disease (KD) and macrophage activation syndrome (MAS).RESULTSTwenty-eight patients fulfilled the case definition of MIS-C. Median age at presentation was 9 years (range: 1 month to 17 years); 50% of patients had preexisting conditions. All patients had laboratory confirmation of SARS-CoV-2 infection. Seventeen patients (61%) required intensive care, including 7 patients (25%) who required inotrope support. Seven patients (25%) met criteria for complete or incomplete KD, and coronary abnormalities were found in 6 cases. Lymphopenia, thrombocytopenia, and elevation in inflammatory markers, D-dimer, B-type natriuretic peptide, IL-6, and IL-10 levels were common but not ubiquitous. Cytopenias distinguished MIS-C from KD and the degree of hyperferritinemia and pattern of cytokine production differed between MIS-C and MAS. Immunomodulatory therapy given to patients with MIS-C included intravenous immune globulin (IVIG) (71%), corticosteroids (61%), and anakinra (18%). Clinical and laboratory improvement were observed in all cases, including 6 cases that did not require immunomodulatory therapy. No mortality was recorded in this cohort.CONCLUSIONMIS-C encompasses a broad phenotypic spectrum with clinical and laboratory features distinct from KD and MAS.FUNDINGThis work was supported by the National Institutes of Health, National Institute of Arthritis and Musculoskeletal and Skin Diseases; the National Institute of Allergy and Infectious Diseases; Rheumatology Research Foundation Investigator Awards and Medical Education Award; Boston Children's Hospital Faculty Career Development Awards; the McCance Family Foundation; and the Samara Jan Turkel Center.

407 Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

Background

XmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report preliminary data from an ongoing, multicenter, Phase 1 study investigating the safety/tolerability, pharmacokinetics/pharmacodynamics, and clinical activity (RECIST 1.1) of XmAb20717 in patients with selected advanced solid tumors.

Methods

A 3+3 dose-escalation design was used to establish a maximum tolerated (MTD)/recommended dose for evaluation in parallel expansion cohorts, including melanoma, renal cell carcinoma, non-small cell lung cancer (NSCLC), prostate cancer, and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI; n≤20 each). XmAb20717 was administered as an infusion on Days 1 and 15 of each 28-day cycle.

Results

As of 08Jul2020, 109 patients had been treated (table 1), and 30 were continuing treatment. In escalation, 6 dose levels (0.15–10.0 mg/kg) were evaluated (n=34); an MTD was not established. Expansion cohorts were initiated at 10 mg/kg (n=72), and a 15 mg/kg escalation cohort was added (n=3). T-cell proliferation was noted in peripheral blood at doses as low as 3 mg/kg and was highest at 10 mg/kg. At this dose, consistent proliferation of CD8+ and CD4+ T cells was observed, indicative of dual PD-1 and CTLA-4 checkpoint blockade (figure 1). Paired pre- and post-dosing biopsies showed increased intratumoral T-cell infiltration and IFN-response signatures following treatment. Grade 3/4 treatment-related adverse events (TRAEs) reported for ≥3 patients included rash (13%), transaminase elevations (7%), lipase increased (4% [2% with amylase increased]), and acute kidney injury (3%), all considered immune-related. There were 2 Grade 5 TRAEs: immune-mediated pancreatitis (in the presence of pancreatic metastases) and immune-mediated myocarditis (Grade 4) that contributed to respiratory failure. A complete response was reported as the best overall response for 1 patient (melanoma); partial responses were reported for 5 patients (2 melanoma, 2 NSCLC, 1 ovarian). The objective response rate was 13% overall and 21% at 10 mg/kg (6/46 and 6/29 evaluable patients, respectively). All responders had prior CI exposure. Responses were observed only at 10 mg/kg and, within the 10 mg/kg group, appeared to correlate with higher peak serum concentration and area under the curve.

Abstract 407 Table 1

Demographics and baseline characteristics

Abstract 407 Figure 1

Mean change from baseline in percentage of Ki67+ T–cell expression in peripheral blood during first two cycles of XmAb20717

Conclusions

XmAb20717 induced T-cell proliferation in peripheral blood consistent with dual-checkpoint blockade. Preliminary data indicate XmAb20717 was generally well-tolerated and associated with evidence of antitumor activity in CI-pretreated patients with various types of advanced solid tumors.

Trial Registration

NCT03517488

Ethics Approval

The study was approved by each institution’s IRB.

Increased maternal new-onset psychiatric disorders after delivering a child with a major anomaly: a cohort study

BACKGROUND

The birth of a child with a major congenital anomaly may create chronic caregiving stress for mothers, yet little is known about their psychiatric outcomes.

AIMS

To evaluate the association of the birth of a child with a major congenital anomaly with subsequent maternal psychiatric risk.

METHODS

This Danish nationwide cohort study included mothers who gave birth to an infant with a major congenital anomaly (n = 19 220) between 1997 and 2015. Comparators were randomly selected mothers, matched on maternal age, year of delivery and parity (n = 195 399). The primary outcome was any new-onset psychiatric diagnosis. Secondary outcomes included specific psychiatric diagnoses, psychiatric in-patient admissions and redeemed psychoactive medicines. Cox models were used to estimate hazard ratios (HRs), adjusted for socioeconomic and medical variables.

RESULTS

Mothers of affected infants had an elevated risk for a new-onset psychiatric disorder vs. the comparison group (adjusted HR, 1.16, 95% CI 1.11-1.22). The adjusted HR was particularly elevated during the first postpartum year (1.65, 95% CI 1.42-1.90), but remained high for years, especially among mothers of children with multiorgan anomalies (1.37, 95% CI 1.18-1.57). The risk was also elevated for most specific psychiatric diagnoses, admissions and medicines.

CONCLUSIONS

Mothers who give birth to a child with a major congenital anomaly are at increased risk of new-onset psychiatric disorders, especially shortly after birth and for mothers of children with more severe anomalies. Our study highlights the need to screen for mental illness in this high-risk population, as well as to integrate adult mental health services and paediatric care.

Abstract IA16: Augmenting anti-PD1 activity via an HLA-agnostic, mutation-burden independent, personalized neoantigen vaccine strategy

Neoantigens (neoAg) offer a unique opportunity for directing a patient’s adaptive immune system against tumors while avoiding damage to normal tissues. Current methods for their accurate identification and therapeutic targeting suffer from three main drawbacks: 1) they predict rather than confirm neoAg, 2) their “hit rate” is often too low to be useful in tumors of low to moderate mutational burden such as HNSCC, and, 3) they fail to inform on whether a given mutation is a natural target that can be recognized by CD8+ T cells on tumor cells or by CD4+ T cells on local antigen-presenting cells (APC). This last aspect is perhaps most critical, as a T cell that recognizes a peptide but not a target cell is of little therapeutic value to a cancer patient. We have developed a new unbiased functional approach to neoAg identification that combines bioinformatic analysis of genomic sequence data with functional T-cell assays from a patient’s own PBMC and tumor-infiltrating lymphocytes (TIL). It is based on the concept that, although in silico algorithms may seek to model one or another features of a given mutation’s predicted immunogenicity, the intact immune system can provide proof as to which mutations have been targeted by T cells, and does so according to defined rules of antigen processing and presentation that operate in both cross-presenting antigen-presenting cells (APC) that prime the response and in the tumor cells that express the source antigen. Our approach does not rely on in silico prediction of MHC binding nor any other speculative aspect of peptide immunogenicity and has minimal tissue and peripheral blood requirements. Our preliminary data show it can identify neoAg at a 10x higher rate than current methods and reveals both CD4+ and CD8+ responses. We have performed this analysis for the 4 neoAg identified for the syngeneic murine SCC VII model, and find that the prime/boost vaccination protocol results in significant but incomplete protection from challenge with live SCC VII tumor cells, thus demonstrating that, as a pool, these peptides induce T cells capable of tumor recognition. Furthermore, we have performed preliminary experiments demonstrating that, although SCC VII tumor responds to both PD-1 and CTLA4 blockade immunotherapy, the growing tumors are eradicated much faster in mice that had a pre-existing neoAg-specific T cell response induced in them prior to challenge and treatment. Mice that were vaccinated twice with neoAg peptides + polyI:C but did not receive immune checkpoint blockade showed some initial tumor control that was subsequently lost, leading to progressive growth. A phase 1b clinical trial is now enrolling subjects with advanced cancer that will produce a personalized vaccine for each patient based on our neoantigen identification methodology. The trial combines the vaccine with the anti-PD1 antibody, pembrolizumab, and enrolls patients into 2 consecutive cohorts to elucidate the effects on neoepitope specific T-cell responses of the vaccine versus anti-PD1 targeting. This presentation will summarize our efforts to identify neoantigens, efficacy of a neoantigen-specific vaccine in the murine model, and the current phase 1b study rationale and design.

Citation Format: Ezra Cohen. Augmenting anti-PD1 activity via an HLA-agnostic, mutation-burden independent, personalized neoantigen vaccine strategy [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr IA16.