Pilot study of bempegaldesleukin in combination with nivolumab in patients with metastatic sarcoma

PD-1 blockade (nivolumab) efficacy remains modest for metastatic sarcoma. In this paper, we present an open-label, non-randomized, non-comparative pilot study of bempegaldesleukin, a CD122-preferential interleukin-2 pathway agonist, with nivolumab in refractory sarcoma at Memorial Sloan Kettering/MD Anderson Cancer Centers (NCT03282344). We report on the primary outcome of objective response rate (ORR) and secondary endpoints of toxicity, clinical benefit, progression-free survival, overall survival, and durations of response/treatment. In 84 patients in 9 histotype cohorts, all patients experienced ≥1 adverse event and treatment-related adverse event; 1 death was possibly treatment-related. ORR was highest in angiosarcoma (3/8) and undifferentiated pleomorphic sarcoma (2/10), meeting predefined endpoints. Results of our exploratory investigation of predictive biomarkers show: CD8 + T cell infiltrates and PD-1 expression correlate with improved ORR; upregulation of immune-related pathways correlate with improved efficacy; Hedgehog pathway expression correlate with resistance. Exploration of this combination in selected sarcomas, and of Hedgehog signaling as a predictive biomarker, warrants further study in larger cohorts.

Association of immune-related adverse events (irAEs) with improved clinical outcome in sarcoma patients treated with immune checkpoint blockade (ICB)

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Background: IrAEs are associated with improved clinical outcomes after treatment with ICB in select epithelial malignancies. We hypothesized that sarcoma patients (pts) treated with ICB who developed an irAE would have improved outcomes compared to pts who had no irAE. Methods: Adverse events (AEs) from 3 sarcoma-specific ICB trials (nivolumab plus NKTR-214, pembrolizumab plus epacadostat, and pembrolizumab plus T-VEC) were reviewed. AEs probably or definitely related to ICB were classified as immune- or non-immune-related by the principal investigator. Endpoints of interest included best overall response (BOR) by RECIST 1.1 (complete response [CR]/partial response [PR]), durable clinical benefit (DCB; CR/PR/stable disease [SD] ≥ 16 weeks), and progression-free survival (PFS). Outcomes were stratified by the presence or absence of ≥ 1 irAE of any grade and by grade 1-2, grade 3-4, or no irAE (three-category comparison). Results: A total of 124 pts received ICB on these studies. Median pt age was 56 (range: 13-90); 53% were male; all but one pt had a performance status of ≤ 1. BOR was PR in 12 pts, SD in 41, and PD in 69. 2 pts were not evaluable. 40 pts (32%) had ≥ 1 irAE of any grade, 6 of whom had a grade 3-4 irAE. The most common irAEs (≥ 5% of pts) were rash (15%), arthralgia (11%), myalgia (9%), pruritis (8%), and hypothyroidism (6%). The proportion of pts with a CR/PR was higher in pts with than without an irAE (18% vs. 6%, respectively; P = 0.058). A significantly higher proportion of pts with an irAE had DCB compared to those without (53% and 29%, respectively; P = 0.017). The median PFS of pts with an irAE was 16.6 months compared to 10.6 in those without (P = 0.013). The proportion of pts with a grade 3-4 irAE and a CR/PR was highest (33%) compared to pts with grade 1-2 (15%) or no irAE (6%) (P = 0.048). More pts with grade 3-4 irAE achieved DCB (67%) than grade 1-2 (50%) or no irAE (29%) (P = 0.027). Median PFS was 22.6, 15, and 10.6 weeks in the grade 3-4, grade 1-2, and no irAE groups, respectively (P = 0.047). Conclusions: Approximately one-third of advanced sarcoma pts with ICB-based immunotherapy developed an irAE. As reported previously in select carcinomas, sarcoma pts with irAEs were more likely to have clinical benefit than those without irAEs. Further research is needed to understand the mechanism behind this association and to validate these findings prospectively.

Pilot study of NKTR214 and nivolumab in patients with sarcomas

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Background: Monotherapy checkpoint inhibitors have minimal efficacy in most patients with metastatic sarcoma. NKTR-214 is a CD122-preferential IL-2 pathway agonist that activates and expands natural killer and CD8+ T cells. Phase I/II data demonstrated the safety and efficacy of nivolumab plus NKTR-214 in multiple tumor types. A trial of NKTR-214 plus nivolumab was initiated in patients with selected sarcomas. Methods: This is a multi-center pilot study enrolling patients (pts) failing prior regimens within 9 cohorts: leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), dedifferentiated liposarcoma (DDLPS), chondrosarcoma (CS), osteosarcoma (OS), angiosarcoma (AS), alveolar soft part sarcoma (ASPS), synovial sarcoma/small blue round cell and other. Pts received NKTR 0.006mg/kg with nivolumab 360 mg every 3 weeks. Primary endpoint was objective response rate (ORR), secondary endpoints were adverse events (AEs), progression-free, overall survival (PFS,OS) and clinical benefit rate (CBR.) Pre/on treatment biopsies performed on patients for correlative studies including PD-L1 expression and TIL characterization by immunohistochemistry, whole exome sequencing and RNAseq. Results: Enrollment completed with 10 patients in cohorts below. 50 pts enrolled (median age 58, range 14-80), 54% female. Median follow-up time is 13m. 50% of patients were refractory ≥3 lines of therapy. Grade 3/4 treatment related adverse events occurred in 26% of patients. 2% of patients stopped due to AEs. Median time to response was 3.6m. Responses seen in LMS, UPS, dedifferentiated CS; on-going in UPS/CS. Prolonged disease stability in DDLPS. 6 patients remain on treatment. Conclusions: Nivolumab plus NKTR-214 was safe and tolerable in heavily pre-treated and refractory sarcoma patients. Responses were protracted overtime; on-going in UPS and dedifferentiated CS. Prolonged disease stability seen in DDLPS in patients. All correlative analyses are in progress and will be presented. Enrollment continues with plans to add a treatment naïve cohort. Clinical trial information: NCT03282344. [Table: see text]

Somatic mutational profile of Merkel cell carcinoma treated with immune checkpoint blockade: Preliminary results from a planned multiplatform analysis

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Background: Merkel cell carcinoma (MCC) is an immunogenic neuroendocrine malignancy with promising responses to immune checkpoint blockade (ICB). Although ICB is standard of care in advanced MCC patients, approximately 50% of patients are resistant to ICB. Thus, it is crucial to identify biomarkers predictive of response. Methods: To understand the genomic landscape of MCC, we performed exome capture sequencing on 27 tumor and matched normal samples from 25 patients with MCC treated at Memorial Sloan Kettering. Herein, we report the analysis of 16 paired samples from 14 patients. Nonsynonymous, high-confidence somatic mutations were identified and tumor reads aligned to the Merkel cell polyoma virus (MCPyV) were quantified. Results: Tumor and matched normal samples were sequenced to a median target coverage depth of 53x and 79x reads, respectively. One sample was not analyzed due to inadequate coverage. The MCPyV genome was detected in 12 of 13 patients (92%). The median somatic mutation burden among analyzed samples was 19 nonsynonymous variants per exome (range: 8 - 120). No recurrent driver mutations were identified in any sample. Four samples lacked potential driver mutations and, among the remaining 11 samples, 36 putatively oncogenic mutations were detected in 33 genes (variant allele frequency: 0.08 – 1), including genes involved in the cell cycle checkpoint ( TP53, RB1), DNA damage repair ( ERCC4, FANCA, FANCD2), PI3K-AKT-mTOR ( PIK3CA, PIK3CG), and Notch ( NOTCH1, NOTCH2) pathways. One sample with undetected MCPyV DNA demonstrated loss of heterozygosity of both TP53 and RB1. Four samples contained strand coordinated clusters of mutations in more than 20 distinct gene regions, suggesting an APOBEC-high mutagenesis signature. Conclusions: The MCPyV genome was detected in most tumors analyzed and tumor mutation burden was low in such tumors, consistent with published literature. Analysis of an additional 11 sample pairs is ongoing, along with personalized neoantigen binding predictions on all samples. Immunohistochemistry (IHC) for PDL1 and CD8 expression is in progress. Associations between the aforementioned and response to ICB will be reported.