Schuetze, Scott M.

TPS10591 Background: Osteosarcoma is a rare cancer and 33% of patients who have completed primary treatment will recur. The Src pathway has been implicated in the metastatic behavior of several tumors including osteosarcoma where 95% of samples express Src or have evidence of downstream activation of this pathway. Saracatinib (AZD0530) is a potent and selective Src kinase inhibitor. The recommended phase II dose in adults was found to be 175mg daily. The primary goal of this study is to determine if treatment with Saracatinib can increase progression free survival (PFS) for patients who have undergone complete resection of metastatic osteosarcoma nodules in the lung. Secondary goals are evaluation of overall survival, time to treatment failure, and evaluation of several biological correlatives. Methods: This is a multi-institutional, phase II.5, placebo-controlled study with an accrual goals of 88 randomized patients. Patients between 15 and 75 years, with histological confirmation of recurrent osteosarcoma, localized to the lung, who have potential for complete surgical resection, are eligible for enrollment. After complete resection, patients are randomized to treatment with saracatinib or placebo, of a daily oral dose of 175 mg, continuously for up to 1 year or until progression. Patients who recur in the lung while on-study and who are amenable to complete surgical resection will be un-blinded. Those patients who received placebo may have the option to undergo surgical resection. If fully resected, they will be offered therapy with saracatinib under the same treatment guidelines as above. As of January 2013, 38 patients have enrolled and 32 patients met the criteria to be randomized and began oral therapy with either saracatinib or placebo. An interim analysis is planned after 40 patients have been randomized. Clinical trial information: NCT00752206.

10003 Background: Preclinical studies demonstrate synergistic anti-tumor activity by inhibiting mTOR and IGF-1R. This study evaluated the safety and efficacy of A12 and TEM in 3 chemo-refractory cohorts: IGF-1R (+) STS (Arm A), IGF-1R (+) bone (Arm B), and IGF-1R (-) bone and STS (Arm C). Methods: An optimal Simon 2 stage design was used for each arm. The primary end-point was progression free survival (PFS) at 12 weeks. Based on historical data, a 40% PFS rate was considered promising and a 20% PFS non-promising (type I/ II error, 0.05/0.10). ≥5 PFSs at 12 weeks were required in the first 19 and ≥16 PFSs were required in a total of 54 pts to consider each arm positive. Key eligibility: measurable disease (RECIST 1.1), age ≥18, 1- 4 priors, ECOG status 0-1. A12 (6 mg/kg) and TEM (25 mg) were administered IV weekly. Pre and post treatment tumor biopsies and plasma for IGF-1 and IGFBP3 were obtained. 20 Sarcoma Centers participated. Results: Starting in 02/2010, 383 pts were tested for IGF-1R by immunohistochemistry (IHC; 54% +) and 171 were treated: mean age 47 (range: 18-80), mean # priors 2.2 (range: 1-4). Grade 3/4 toxicities ≥10%: lymphopenia (12%), mucositis (10%). By intent to treat (ITT) analysis, each arm of the study achieved its primary 12 week PFS end-point (≥16 PFSs): Arm A: 18/56 (32%), Arm B: 19/50 (38%) (4 too early), Arm C: 27/63 (43%). The one-sided 95% CI for 12-week PFS is (0.22, 1), (0.27, 1), and (0.32, 1), respectively. By ITT the median PFS (95% CI) in weeks for each arm is 6.3 (5.9, 12.0), 11.0 (8.0, 18.0) and 11.6 (9.0, 17.9), respectively, and for chondro (n=18), Ewing’s (n=24), and osteo (n=23) only it is 22.6 (5.7, 40.9), 10.4 (5.7, 17.9) and 6.0 (6.0, 18.0), respectively. Westerns on 32 matched pair tumor biopsies indicate inhibition of IGF-1R, pAKT and pS6. Of biopsies on 7 IGF-1R (-) IHC pts (Arm C), 5 were IGF-1R (+) by western. Plasma biomarkers did not correlate with PFS. Conclusions: A12 and TEM met its primary end-point of improved PFS in pts with metastatic sarcoma. This effect was independent of IGF-1R status by IHC. These results support further clinical development of this combination in bone and STS.

11015 Background: Immune checkpoint inhibitors have demonstrated activity in multiple tumor types but their activity in soft tissue sarcomas remains limited. In the multicenter phase II study, SARC028, the anti-PD-1 antibody, P demonstrated objective responses that were largely restricted to UPS and LPS subtypes. We now report outcomes from 2 expansion cohorts of SARC 028 in advanced UPS and LPS. Methods: To further confirm the clinical activity of P in UPS and LPS, we enrolled an additional 30 pts in each of 2 expansion cohorts for a total of 40 UPS and 40 LPS pts. Primary endpoint was investigator-assessed response by RECIST v1.1. Secondary endpoints were safety, progression-free survival (PFS), 12-week PFS rate, and overall survival (OS). An ORR of 25% was considered clinically meaningful and < 10% was considered to show lack of efficacy. P was to be considered a success if 8 or more of 40 enrolled patients had a PR or better (1-sided α = 0.042, 82% power). Pts age ≥18 with advanced, refractory UPS or LPS received 200 mg of P IV every 3 weeks until progression or unacceptable toxicity. Results: Preliminary results from the first 10 pts in each of the UPS and LPS cohorts have been reported. We now present summary data after enrolling an additional 30 pts in each cohort. The ORR in the UPS cohort was 23% (9/40), with an additional 5/30 PRs observed in the expansion cohort (total 2 CRs, 7 PRs). In the LPS cohort, the ORR was 10% (4/39 evaluable pts), with an additional 2/30 PRs observed (total 4 PRs). Median PFS for the UPS group was 3 months [95% CI: 2, 5] and 2 months [95% CI: 2, 4] for the LPS group. 12-week PFS rate was 50% in UPS [95% CI: 35, 65] and 44% in LPS [95% CI: 28, 60]. The UPS group had a median OS of 12 months [95% CI: 7, 34] and 13 months [95% CI: 8, NR] for the LPS group. P was well tolerated with no unexpected toxicities. Conclusions: The UPS cohort achieved its primary endpoint, however the activity of P in UPS deserves further evaluation in a randomized study. The activity of P was not confirmed in the LPS cohort. Ongoing biomarker analyses may direct better patient selection and guide future combination strategies. Clinical trial information: NCT02301039.

Abstract Purpose: We recently reported a 17.5% objective RECIST 1.1 response rate in a phase II study of pembrolizumab in patients with advanced sarcoma (SARC028). The majority of responses occurred in undifferentiated pleomorphic sarcoma (UPS) and dedifferentiated liposarcoma (DDLPS). We sought to determine whether we can identify immune features that correlate with clinical outcomes from tumor tissues obtained pre- and on-treatment. Patients and Methods: Pretreatment (n = 78) and 8-week on-treatment (n = 68) tumor biopsies were stained for PD-L1 and multiplex immunofluorescence panels. The density of positive cells was quantified to determine associations with anti–PD-1 response. Results: Patients that responded to pembrolizumab were more likely to have higher densities of activated T cells (CD8+ CD3+ PD-1+) and increased percentage of tumor-associated macrophages (TAM) expressing PD-L1 pre-treatment compared with non-responders. Pre-treatment tumors from responders also exhibited higher densities of effector memory cytotoxic T cells and regulatory T cells compared with non-responders. In addition, higher density of cytotoxic tumor-infiltrating T cells at baseline correlated with a better progression-free survival (PFS). Conclusions: We show that quantitative assessments of CD8+ CD3+ PD-1+ T cells, percentage of TAMs expressing PD-L1, and other T-cell densities correlate with sarcoma response to pembrolizumab and improved PFS. Our findings support that multiple cell types present at the start of treatment may enhance tumor regression following anti–PD-1 therapy in specific advanced sarcomas. Efforts to confirm the activity of pembrolizumab in an expansion cohort of patients with UPS/DDLPS are underway.

60 Background: The activity of the anti-PD-1 antibody P in pts with advanced STS was evaluated in a prospective multicenter Phase II study conducted by the Sarcoma Alliance for Research through Collaboration (SARC). SARC028 enrolled 40 patients with advanced soft tissue sarcoma. Pembro had an ORR of 19% and PFS rate at 12 weeks of 55%, suggesting clinical activity. We investigated biomarkers of response to P. Methods: The primary endpoint was Objective Response Rate (ORR) by RECIST 1.1. Secondary endpoints included progression-free survival (PFS), overall survival, and biomarkers of response in blood and tumor. Pre- and on-treatment biopsies were required and obtained from over 90% and 72% of pts respectively. Serum was obtained from all pts at baseline and at multiple time points on therapy (pre-, week 8, and every 12 weeks). Sera were examined for candidate circulating biomarkers by Affymetrix Luminex platform array, including PD-L2. To determine whether there is a statistically significant difference between different conditions, we used Mann-Whitney and two-tailed t tests. Log-rank p-values in Kaplan-Meier survival analyses were calculated using the "survival" R package. Results: Forty pts with STS were enrolled into 4 cohorts (10 each) based on histological subtype including undifferentiated pleomorphic sarcoma (UPS), dedifferentiated liposarcoma (LPS), synovial sarcoma (SS), and leiomyosarcoma (LMS). 4 pts with UPS, 2 pts with LPS, and one pt with SS achieved a response. Six of seven responses were durable at the time of this analysis. Circulating levels at baseline or after therapy of PD-1, PD-L1, 4-1BB, IDO, BTLA, CTLA-4, LAG-3, and TIM-3 did not correlate with outcome. However, pre-treatment and week 8 PD-L2 levels correlated best with clinical outcome: high PD-L2 levels were associated with better PFS (p=0.019) in STS. Conclusions: P has clinical activity in specific histologic subtypes of STS, namely UPS and LPS. Pre-treatment circulating PD-L2 levels correlated with progression-free survival and is a novel and promising predictor of improved clinical outcome of PD-1 therapy in STS.

Introduction . Primary cardiac sarcoma (PCS) has a poor prognosis compared to other sarcomas due to late presentation, challenging resection, incidence of metastases, and limited efficacy of systemic therapies. Methods . A medical record search engine was queried to identify patients diagnosed with PCS from 1992 to 2017 at the University of Michigan. Results . Thirty-nine patients with PCS had a median age of 41 years (range 2–77). Common histologies were angiosarcoma (AS, 14), high-grade undifferentiated pleomorphic sarcoma (UPS, 10), and leiomyosarcoma (LMS, 5). Sites of origin were left atrium (18), right atrium (16), and pericardium (5). AS was the most common right-sided tumor; UPS was more common on the left. Eighteen patients presented with metastases involving lung (10), bone (7), liver (5), and brain (4). Twenty-five patients underwent resection, achieving 3 R 0 resections. Patients received a median of 2 (1–6) systemic therapies. Median overall survival (OS) was 12.1 months (range 0–79). Median OS was 14.0 months and 8.2 months in patients who did or did not undergo resection, respectively ( p = 0.018 ). Brain metastases occurred in 12 (31%) patients, 9 (75%) of whom had left heart tumors, at a median of 8.5 months (range 0–75) from diagnosis. Median OS was 5.6 months (range 0–30) after the diagnosis of brain metastases. Conclusions . PCS portends a poor prognosis, because of difficulty in obtaining complete resection of sarcoma, advanced stage at diagnosis, and high risk of brain metastases. Providers should be aware of the increased risk of brain metastases and consider brain imaging at diagnosis and follow-up.

11008 Background: SARC028 is the first multicenter Phase II study of P monotherapy in patients (pts) with STS and BS. Designed to detect clinical efficacy signals in multiple histologies, the study collected blood & tissue samples on all pts. We report extended clinical follow-up and in-depth biomarker correlates of response. Methods: The primary endpoint was objective response rate (ORR) by RECIST 1.1. Secondary endpoints were safety, 12 wk progression-free survival (PFS), and overall survival (OS). The STS arm had 10 pts in each of 4 cohorts: undifferentiated pleomorphic sarcoma (UPS), dedifferentiated liposarcoma (DDLPS), synovial sarcoma (SS) and leiomyosarcoma (LMS). The BS arm included 40 pts with osteosarcoma (OS), Ewing sarcoma (ES) or dedifferentiated chondrosarcoma (CS). Pre- and on-P biopsies were required as well as blood at multiple time points. Tumor was assessed for PD-L1 expression (clone 22C3) and immune infiltrates by multi-color IHC (Vectra). Ongoing analyses include circulating cytokine and checkpoint levels and exome (DNA), transcriptome (RNA), and T-cell receptor (TCR) sequencing. Results: 86 pts were enrolled, 80 were evaluable for response. For STS, median follow-up was 14.5 months. The ORR in the overall STS cohort was 18% and the 12-wk PFS 55% [95% CI, 42-71]). Clinical activity was variable by histologic subtype with 40% ORR in UPS (1 CR and 3PR out of 10 evaluable pts), 2 PR/10 were seen in DDLPS, 1PR/10 in SS and 0/10 in LMS. For BS, median follow-up was 12.3 months (ORR 5%; 12-wk PFS 28% [95% CI, 14-41]), with 1PR/22 OS, 1PR/5 CS and 0/13 ES. 70 pre-P tissues were analyzed (11 excluded for insufficiency), with PD-L1+ in 3/70 (4%); all 3 were UPS. Of the 2 evaluable pts, 1 had CR and 1 PR. 2 OS were PD-L1+ on multi-color IHC, 1 had PR. All PD-L1+ samples had CD8+ T-cell infiltration. There were no post-P PD-L1+ samples. Conclusions: P has clinical activity in UPS and LPS, and expansion cohorts in those subtypes are planned. Pre-treatment PD-L1 expression was infrequent, but correlated with T-cell infiltration and response in UPS & OS. Ongoing biomarker analyses that may guide combination strategies are ongoing and will be presented at the meeting. Clinical trial information: NCT02301039.