Synovial sarcoma: characteristics, challenges, and evolving therapeutic strategies

Synovial sarcoma (SS) is a rare and aggressive disease that accounts for 5%-10% of all soft tissue sarcomas. Although it can occur at any age, it typically affects younger adults and children, with a peak incidence in the fourth decade of life. In >95% of cases, the oncogenic driver is a translocation between chromosomes X and 18 that leads to the formation of the SS18::SSX fusion oncogenes. Early and accurate diagnosis is often a challenge; optimal outcomes are achieved by referral to a specialist center for diagnosis and management by a multidisciplinary team as soon as SS is suspected. Surgery with or without radiotherapy and/or chemotherapy can be effective in localized disease, especially in children. However, the prognosis in the advanced stages is poor, with treatment strategies that have relied heavily on traditional cytotoxic chemotherapies. Therefore, there is an unmet need for novel effective management strategies for advanced disease. An improved understanding of disease pathology and its molecular basis has paved the way for novel targeted agents and immunotherapies that are being investigated in clinical trials. This review provides an overview of the epidemiology and characteristics of SS in children and adults, as well as the patient journey from diagnosis to treatment. Current and future management strategies, focusing particularly on the potential of immunotherapies to improve clinical outcomes, are also summarized.

Circulating tumor DNA analysis of the phase III VOYAGER trial: KIT mutational landscape and outcomes in patients with advanced gastrointestinal stromal tumor treated with avapritinib or regorafenib

BACKGROUND

The current treatment paradigm of imatinib-resistant metastatic gastrointestinal stromal tumor (GIST) does not incorporate KIT/PDGFRA genotypes in therapeutic drug sequencing, except for PDGFRA exon 18-mutant GIST that is indicated for avapritinib treatment. Here, circulating tumor DNA (ctDNA) sequencing was used to analyze plasma samples prospectively collected in the phase III VOYAGER trial to understand how the KIT/PDGFRA mutational landscape contributes to tyrosine kinase inhibitor (TKI) resistance and to determine its clinical validity and utility.

PATIENTS AND METHODS

VOYAGER (N = 476) compared avapritinib with regorafenib in patients with KIT/PDGFRA-mutant GIST previously treated with imatinib and one or two additional TKIs (NCT03465722). KIT/PDGFRA ctDNA mutation profiling of plasma samples at baseline and end of treatment was assessed with 74-gene Guardant360® CDx. Molecular subgroups were determined and correlated with outcomes.

RESULTS

A total of 386/476 patients with KIT/PDGFRA-mutant tumors underwent baseline (pre-trial treatment) ctDNA analysis; 196 received avapritinib and 190 received regorafenib. KIT and PDGFRA mutations were detected in 75.1% and 5.4%, respectively. KIT resistance mutations were found in the activation loop (A-loop; 80.4%) and ATP-binding pocket (ATP-BP; 40.8%); 23.4% had both. An average of 2.6 KIT mutations were detected per patient; 17.2% showed 4-14 different KIT resistance mutations. Of all pathogenic KIT variants, 28.0% were novel, including alterations in exons/codons previously unreported. PDGFRA mutations showed similar patterns. ctDNA-detected KIT ATP-BP mutations negatively prognosticated avapritinib activity, with a median progression-free survival (mPFS) of 1.9 versus 5.6 months for regorafenib. mPFS for regorafenib did not vary regardless of the presence or absence of ATP-BP/A-loop mutants and was greater than mPFS with avapritinib in this population. Secondary KIT ATP-BP pocket mutation variants, particularly V654A, were enriched upon disease progression with avapritinib.

CONCLUSIONS

ctDNA sequencing efficiently detects KIT/PDGFRA mutations and prognosticates outcomes in patients with TKI-resistant GIST treated with avapritinib. ctDNA analysis can be used to monitor disease progression and provide more personalized treatment.

Mutational heterogeneity of imatinib resistance and efficacy of ripretinib vs sunitinib in patients with gastrointestinal stromal tumor: ctDNA analysis from INTRIGUE

397784

Background: Ripretinib, a switch-control tyrosine kinase inhibitor (TKI), is indicated for patients (pts) with gastrointestinal stromal tumor (GIST) who received prior treatment with ≥3 TKIs, including imatinib. Sunitinib is approved for advanced GIST after imatinib failure. Circulating tumor DNA (ctDNA) analysis may provide insight into the efficacy of these agents in second-line advanced GIST. Here, we present exploratory baseline ctDNA results from INTRIGUE. Methods: INTRIGUE is an open-label, phase 3 study that enrolled adult pts with advanced GIST who progressed on or had intolerance to imatinib (NCT03673501). Randomization was 1:1 to ripretinib 150 mg once daily (QD) or sunitinib 50 mg QD (4 wks on/2 wks off). Baseline peripheral whole blood was analyzed by Guardant360, a 74-gene ctDNA next-generation sequencing (NGS)-based assay. Only KIT mutations are reported here. Results: Of 453 pts in the overall intent-to-treat (ITT) population, 362 (80%) samples were analyzed. ctDNA was detected in 280/362 (77%), with KIT mutations detected in 213/280 (76%). Common resistance mutations were in the KIT activation loop (AL; exons 17/18; 89/213, 42%) and ATP-binding pocket (ATP-BP; exons 13/14; 81/213, 38%). Efficacy in pts with detectable ctDNA in the KIT exon 11 and overall ITT populations was consistent with the primary analysis based on tumor data used for randomization. Pts with KIT exon 11 + 17/18 (−9/13/14) mutations had superior progression-free survival (PFS), objective response rate (ORR), and overall survival (OS) with ripretinib vs sunitinib, whereas pts with exon 11 + 13/14 (−9/17/18) mutations had better PFS, ORR, and OS with sunitinib vs ripretinib (Table). Subgroup safety profiles were consistent with the primary analysis. Conclusions: While KIT ATP-BP mutations predicted clinical benefit from sunitinib vs ripretinib, pts harboring resistance mutations in the KIT AL derived meaningful clinical benefit from ripretinib but not sunitinib. This study demonstrates the value of ctDNA NGS-based sequencing of the complex landscape of KIT mutations to predict the clinical benefit of ripretinib or sunitinib as second-line therapy in pts with advanced GIST. Clinical trial information: NCT03673501 . [Table: see text]

Informed consent in clinical trials: Implementing methods to improve patient understanding in cancer research—A quality improvement initiative in a sarcoma trials unit

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Background: Clinical trials are considered the cornerstone of improving outcomes for cancer patients. The understanding of an individual patient of the trial on which they are enrolled can vary significantly, with some studies demonstrating poor patient understanding of their involvement in trials. This exploratory study aimed to improve patient understanding of clinical trials and patient experience of the informed consent process by implementing measures to present complex trial information in alternative formats. Methods: The project was undertaken in a sarcoma trials unit in a specialist cancer treatment centre. Baseline knowledge was assessed using an adapted version of the Quality of Informed Consent (QuIC) questionnaire. A decision-aid was created following focus group discussions with stakeholders, focussing on key trial questions for patients, such as consent, the research description, risks, benefits, and alternatives to the trial. A patient education video was produced by the research team, explaining general aspects of clinical trials in patient-friendly language. The decision-aids and videos were distributed during the informed consent process of trial recruitment over a 12-week period. The patient group was assessed with post-intervention questionnaires. Statistical analysis was descriptive due to the small numbers. Results: Thirty sarcoma patients participated in the project, including baseline assessment of 15 patients previously enrolled on study, and 15 patients considering participation in a trial who underwent the intervention. 100% (n = 15) of the interventional group found the video and decision-aid useful. 60% (n = 18) of patients had a university level education, indicating a well-educated population. A pre- and post-intervention comparison demonstrated an improved understanding of 10 key elements of clinical trial information as shown in Table. Conclusions: Our exploratory study has shown that patient education tools including decision-aids and patient videos can be successfully implemented to help improve patient understanding of clinical trial information and may be of benefit in other trials units. Further larger studies are required to confirm these findings.[Table: see text]

Percutaneous cryoablation for desmoid fibromatosis: initial experience at a UK centre

AIM

To report the first UK experience of cryoablation in desmoid fibromatosis (DF) with particular focus on technique, safety, and efficacy.

MATERIALS AND METHODS

Patients were selected at multidisciplinary tumour board meetings at a specialist cancer hospital. Radiation dose, procedure duration, and number of cryoprobes were compared for small versus large tumours (>10 cm long axis). Response at magnetic resonance imaging (MRI) was evaluated using different criteria, and percentage agreement with clinical response as assessed in oncology clinic calculated.

RESULTS

Thirteen procedures were performed in 10 patients (eight women, median age 51 years, IQR 42-69 years) between February 2019 and August 2021. Procedures for large tumours had higher radiation dose (2,012 ± 1,012 versus 1,076 ± 519 mGy·cm, p=0.048) used more cryoprobes (13 ± 7 versus 4 ± 2, p=0.009), and were more likely to have residual unablated tumour (38 ± 37% versus 7.5 ± 10%, p=0.045). Adverse events were minor apart from one transient radial nerve palsy. Eight of 10 patients had symptomatic benefit at clinical follow-up (median 353 days, IQR 86-796 days), and three started systemic therapy mean 393 days later. All patients who had complete ablation demonstrated symptomatic response, with no instances of repeat treatment, recurrence, or need for systemic therapy during the study period. All progression occurred outside ablation zones.

CONCLUSION

Cryoablation for symptomatic DF is a reproducible technique with low, transient toxicity, where one or two treatments can achieve a meaningful response. Where possible, the ablation ice ball should fully cover DF tumours.

Efficacy and safety of ripretinib in patients with KIT-altered metastatic melanoma

BACKGROUND

Ripretinib, a broad-spectrum KIT and platelet-derived growth factor receptor A switch-control tyrosine kinase inhibitor, is approved for the treatment of adult patients with advanced gastrointestinal stromal tumor as ≥ fourth-line therapy. We present the efficacy and safety of ripretinib in patients with KIT-altered metastatic melanoma enrolled in the expansion phase of the ripretinib phase I study.

PATIENTS AND METHODS

Patients with KIT-altered metastatic melanoma were enrolled and treated with ripretinib at the recommended phase II dose of 150 mg once daily in 28-day cycles. Investigator-assessed responses according to Response Evaluation Criteria In Solid Tumors version 1.1 were carried out on day 1 of cycles 3, 5, 7, every three cycles thereafter, and at a final study visit.

RESULTS

A total of 26 patients with KIT-altered metastatic melanoma (25 with KIT mutations, 1 with KIT-amplification) were enrolled. Patients had received prior immunotherapy (n = 23, 88%) and KIT inhibitor therapy (n = 9, 35%). Confirmed objective response rate (ORR) was 23% [95% confidence interval (CI) 9%-44%; one complete and five partial responses] with a median duration of response of 9.1 months (range, 6.9-31.3 months). Median progression-free survival (mPFS) was 7.3 months (95% CI 1.9-13.6 months). Patients without prior KIT inhibitor therapy had a higher ORR and longer mPFS (n = 17, ORR 29%, mPFS 10.2 months) than those who had received prior KIT inhibitor treatment (n = 9, ORR 11%, mPFS 2.9 months). The most common treatment-related treatment-emergent adverse events (TEAEs) of any grade in ≥15% of patients were increased lipase, alopecia, actinic keratosis, myalgia, arthralgia, decreased appetite, fatigue, hyperkeratosis, nausea, and palmar-plantar erythrodysesthesia syndrome. There were no grade ≥4 treatment-related TEAEs.

CONCLUSIONS

In this phase I study, ripretinib demonstrated encouraging efficacy and a well-tolerated safety profile in patients with KIT-altered metastatic melanoma, suggesting ripretinib may have a clinically meaningful role in treating these patients.

Systemic treatment of advanced clear cell sarcoma: results from a retrospective international series from the World Sarcoma Network

Background

Clear cell sarcoma (CCS) is a translocated aggressive malignancy with a high incidence of metastases and poor prognosis. There are few studies describing the activity of systemic therapy in CCS. We report a multi-institutional retrospective study of the outcomes of patients with advanced CCS treated with systemic therapy within the World Sarcoma Network (WSN).

Materials and methods

Patients with molecularly confirmed locally advanced or metastatic CCS treated with systemic therapy from June 1985 to May 2021 were included. Baseline demographic and treatment information, including response by Response Evaluation Criteria in Solid Tumours (RECIST) 1.1, was retrospectively collected by local investigators. Descriptive statistics were carried out.

Results

Fifty-five patients from 10 institutions were included. At diagnosis, the median age was 30 (15-73) years and 24% (n = 13/55) had metastatic disease. The median age at diagnosis was 30 (15-73) years. Most primary tumours were at aponeurosis (n = 9/55, 16%) or non-aponeurosis limb sites (n = 17/55, 31%). The most common fusion was EWSR1–ATF1 (n = 24/55, 44%). The median number of systemic therapies was 1 (range 1-7). The best response rate was seen for patients treated with sunitinib (30%, n = 3/10), with a median progression-free survival of 4 [95% confidence interval (CI) 1-7] months. The median overall survival for patients with advanced/metastatic disease was 15 months (95% CI 3-27 months).

Conclusions

Soft tissue sarcoma-type systemic therapies have limited benefit in advanced CCS and response rate was poor. International, multicentre prospective translational studies are required to identify new treatments for this ultra-rare subtype, and access to early clinical trial enrolment remains key for patients with CCS.

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This is the largest reported series of advanced CCS patients treated with systemic therapy.

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The activity of sarcoma-type systemic therapy is poor and modest responses were seen only with sunitinib.

•

Effective therapies are needed to improve outcomes for patients with this ultra-rare sarcoma type.

Patient reported outcomes and tolerability in patients receiving ripretinib versus sunitinib after imatinib treatment in INTRIGUE: A phase 3 open-label study

11541

Background: Ripretinib (R) is a switch-control tyrosine kinase inhibitor (TKI) indicated for the treatment of patients (pts) with advanced gastrointestinal stromal tumor (GIST) after prior treatment with ≥3 TKIs. In the INTRIGUE study (NCT03673501) there was no significant difference in median PFS (primary endpoint) between R and sunitinib (S). We present exploratory analyses of tolerability data and selected pt reported outcomes (PROs). Methods: Pts were randomized 1:1 to R 150 mg QD or S 50 mg QD 4 weeks on/2 weeks off.Dose modification was allowed for toxicity management. The event of interest was severe or life-threatening (grade ≥3) treatment-related adverse event prior to progression (sTRAE). Days with at least one sTRAE were summed for all treated pts and for pts with ≥1 sTRAE event. PROs were assessed using questions from EORTC QLQ-C30 and Dermatology Life Quality Index (DLQI) at cycle 1 (C1) day 1 (D1), D15, and D29; D1 and D29 of all other cycles; as well as at end of treatment. Differences in PRO scores between baseline and later assessments were calculated across visits. Long-term data will be presented. Results: Pts receiving R (n = 223) versus (vs) S (n = 221) experienced fewer sTRAEs (24% vs 51%, respectively). For all treated pts, the mean time with sTRAEs was 11 days for R and 42 days for S (ratio 0.27, P<0.0001). For pts with ≥1 sTRAE, the mean number of days with a sTRAE was 48 days for R vs 81 days for S (ratio 0.59, p = 0.037). Completion of PRO assessments across the two treatment arms was similar (baseline: R [n = 199], S [n = 199]; C1 D29: R [n = 167], S [n = 177]). Significant differences in self-reported functioning and symptoms were observed by C1 D29. For PROs relating to commonly reported sTRAEs, except constipation, pts in the R arm reported better outcomes than pts in the S arm. Pts in the R arm reported significantly (p<0.05) less decline compared to baseline in pt-reported role function as well as less increase, or improvement, in symptoms of fatigue, appetite loss, diarrhea, nausea/vomiting, and pain vs pts in the S arm. Moderate or severe effect of skin toxicity on pt life, as measured by DLQI in the R arm (n = 165) and in the S arm (n = 175), was observed in 6.6% of pts in the R arm vs 14.8% of pts in the S arm (p = 0.015). Conclusions: In the INTRIGUE study the total number of days with sTRAEs was fewer for pts receiving R vs S. Pts in the R arm also reported significantly less decline in pt-reported role function and less increase in symptoms related to commonly reported sTRAEs, except constipation, vs pts in the S arm. Medical writing provided by Costello Medical. Clinical trial information: NCT03673501.

Epitheliod hemagioendothelioma (EHE) patient-derived model (PDX): Drug activity assessment and validation of novel biomarkers

11566

Background: EHE is an ultra-rare sarcoma marked by two specific fusions, WWTR1-CAMTA1 (̃90%) and YAP1-TFE3 (̃10%). The clinical course of EHE ranges from indolent to highly aggressive, often associated with systemic paraneoplastic symptoms. Molecular predictors of clinical outcome are unknown. While surgery is the mainstay of treatment in the localized setting, management of advanced disease is challenging due to the rarity and poor sensitivity to conventional chemotherapy. This hampers the conduct of large prospective clinical trials. We report herein the first available EHE PDX (developed at the Istituto Nazionale Tumori, Milan, Italy) (INT), to assess the activity of old and new anticancer agents in EHE and inform future clinical studies. We also report on the preliminary results of a prospective observational study, ongoing in collaboration with The EHE Rare Cancer Charity (UK) and The EHE Foundation (US) aimed at identifying prognostic factors. Methods: A PDX of EHE in SCID mice was generated at INT from a patient (pt) suffering with the aggressive clinical variant, presenting with systemic symptoms. The PDX fully reproduces the originating clinical tumor in terms of morphology, biology ( WWTR1- CAMTA1 positive), overall transcriptomic profile. 2D (monolayer) and 3D (sferoids) cell cultures were established following PDX disaggregation. We have started assessing the comparative activity of currently available drugs (doxorubicin, sirolimus), while the efficacy of novel agents is undergoing. In parallel, we analyzed the presence of a selection of inflammatory cytokines in prospectively collected blood samples from EHE pts who entered an international observational study and we looked at their presence and modulation in the PDX model. Results: PDX experiments showed almost negligible activity of doxorubicin while sirolimus induced an 80% tumor volume inhibition. Biochemical analysis in tumors explanted from sirolimus-treated mice confirmed the down-regulation of mTOR downstream signaling. Among all cytokines, Growth and Differentiation Factor-15 (GDF-15) was found significantly over-expressed in serum of EHE pts (n = 23), particularly those with the most aggressive clinical variant, compared to healthy subjects (n = 23; p< 0.01). Consistently, EHE PDX and cell culture were found to release in the blood/culture medium GDF-15. Sirolimus was found to down-regulate GDF-15 release in both in vivo and in vitro EHE models. Conclusions: Our preliminary results indicate that this EHE PDX model is suitable i) for comparatively assessing the activity of anticancer drugs, and ii) for identifying and pre-clinically validating novel biomarkers. The role of GDF-15 in EHE progression deserves further investigation.

A randomized, placebo-controlled, phase 2 trial of INBRX-109 in unresectable or metastatic conventional chondrosarcoma

TPS11582

Background: Chondrosarcomas (CS) are the third most common type of primary bone cancer after myeloma and osteosarcoma. Conventional CS represent 85–90% of all cases and are typically treated with surgical resection. However, there are no approved systemic treatment options for patients with unresectable or metastatic conventional CS, and outcomes remain poor. INBRX-109 is a precision-engineered, tetravalent death receptor 5 (DR5) agonist antibody designed to overcome the limitations of earlier-generation agonists and exploit the tumor-specific cell death induced by DR5 activation. DR5 is one of two pro-apoptotic receptors for the trimeric tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Early clinical activity of INBRX-109 was observed in an ongoing phase 1 trial and warrants further investigation. INBRX-109 has been granted an FDA fast-track designation for conventional CS. Methods: This is a multicenter, randomized, blinded, placebo-controlled phase 2 study in patients with unresectable or metastatic conventional CS, measurable disease by RECIST 1.1, and radiologic disease progression within 6 months prior to screening. Any number of prior lines of therapy are allowed, except for prior DR5 agonists. Patients must be ≥18 years of age and have an ECOG performance status of 0/1 and have archival or fresh tissue available. Approximately 201 patients will be randomized (2:1) to INBRX-109 (3 mg/kg intravenously, every 21 days) or placebo, stratified by histologic grade (Grade 1/2 vs 3), isocitrate dehydrogenase (IDH)1 R132/IDH2 R172 status (wildtype vs mutation), and line of systemic therapy (none vs prior). Treatment will continue until disease progression/unacceptable toxicity. Patients treated with a placebo will have the option to cross over to INBRX-109 upon disease progression. The primary endpoint is progression-free survival (PFS) by independent radiology review. Secondary endpoints are overall survival, PFS by investigator assessment, quality of life, overall response rate, duration of response, disease control rate, safety, pharmacokinetics, and immunogenicity. Adverse events will be recorded and graded by NCI CTCAE Version 5.0. Median PFS of 7.0 months is projected for INBRX-109 and 4.0 months for placebo (corresponding hazard ratio of 0.571); INBRX-109 will be declared superior if the 1-sided p-value from the stratified log-rank test is <0.025. More than 50 sites are planned across the US/Europe. The study is actively enrolling. Clinical trial information: NCT04950075.

MANTRA: A randomized, multicenter, phase 3 study of the MDM2 inhibitor milademetan versus trabectedin in patients with de-differentiated liposarcomas

TPS11589

Background: Murine double minute 2 (MDM2) is a negative regulator of tumor suppressor protein p53. MDM2 induces degradation of p53 and promotes tumorigenesis. MDM2 amplification occurs in many cancers but is documented in up to 100% of well-differentiated or dedifferentiated liposarcomas (WD/DDLPS) [Cancer Genome Atlas Research Network. Cell 2017]. Inhibition of the MDM2-p53 interaction is a promising therapeutic approach to restore p53 tumor suppressor activity in WD/DDLPS. Milademetan (RAIN-32) is a small-molecule MDM2 inhibitor that inhibits the MDM2-p53 interaction and restores p53 function at nanomolar concentrations. In a phase 1 study, milademetan showed promising efficacy in 53 patients with WD/DDLPS when administered on an intermittent schedule (260 mg QD on Days 1–3 and 15–17 on a 28-day cycle), with a median progression-free survival (PFS) of 7.4 months [Gounder et al. AACR-NCI-EORTC 2020]. WD/DDLS are relatively resistant to chemotherapy, and systemic treatment options for patients with advanced disease are limited. MANTRA (RAIN-3201) is a randomized, multicenter, open-label, phase 3 registration study designed to evaluate the efficacy and safety of milademetan versus trabectedin in patients with unresectable or metastatic DDLPS with disease progression on ≥ 1 prior systemic therapies. Methods: Eligible patients are ≥ 18 years of age with histologically confirmed unresectable and/or metastatic DDLPS, with or without a WD component, who have received ≥ 1 prior systemic therapies, including ≥ 1 anthracycline-based regimen, with radiographic evidence of progression by RECIST v1.1 within 6 months before study entry. Prior treatment with trabectedin or an MDM2 inhibitor is not permitted. Patients will be randomly assigned (1:1) to receive milademetan (260 mg once daily orally Days 1–3 and 15–17 on a 28-day cycle) or trabectedin (1.5 mg/m2 as a 24-hour intravenous infusion every 3 weeks). Randomization is stratified by Eastern Cooperative Oncology Group performance status (0 or 1) and number of prior treatments for WD/DDLPS (≤ 2 or > 2). Tumor response will be evaluated by RECIST v1.1 at Weeks 8, 16, 24, and 32, and then every 12 weeks. Primary endpoint: PFS by blinded independent central review. Secondary endpoints: overall survival; disease control rate; objective response rate; duration of response; PFS by investigator assessment; safety; health-related quality of life. Exploratory endpoints: molecular markers in peripheral blood and/or tumor tissue; milademetan pharmacokinetics. To demonstrate a 3-month increase in PFS (from 3 to 6 months) corresponding to a hazard ratio of 0.5, approximately 160 patients will be required to observe 105 events with 93.9% power and 2-sided significance level of 5%. Clinical trial information: NCT04979442.

INTRIGUE: A phase III, randomized, open-label study to evaluate the efficacy and safety of ripretinib versus sunitinib in patients with advanced gastrointestinal stromal tumor previously treated with imatinib

359881

Background: Sunitinib is approved for advanced gastrointestinal stromal tumor (GIST) after imatinib failure. Ripretinib, a broad-spectrum KIT and PDGFRA switch-control tyrosine kinase inhibitor (TKI), is indicated for the treatment of adult patients (pts) with GIST who received prior treatment with 3 or more TKIs, including imatinib. We compared the efficacy and safety of ripretinib vs sunitinib in pts with advanced GIST who progressed on or were intolerant to imatinib. Methods: This multicenter, global, randomized, open-label phase 3 study (NCT03673501) enrolled adult pts with GIST who progressed on or had intolerance to imatinib. Pts were randomized 1:1 to ripretinib 150 mg once daily (QD) or sunitinib 50 mg QD (4 wks on/2 wks off). Randomization was stratified by KIT mutational status and imatinib intolerance. The primary endpoint was progression-free survival (PFS) by independent radiologic review (IRR) using modified RECIST version 1.1. Key secondary endpoints were objective response rate (ORR) by IRR and overall survival (OS). Hierarchical testing was performed for primary and key secondary endpoints in a prespecified sequence; testing pts with a KIT exon 11 primary mutation (Ex11 intention-to-treat [ITT] population) preceded the all-patient (AP) ITT population. Data cutoff was 1 Sep 2021; final analyses of PFS and ORR and the first interim analysis of OS were conducted. Results: A total of 453 pts were randomized to ripretinib (n = 226; Ex11 ITT, n = 163) or sunitinib (n = 227; Ex11 ITT, n = 164). Median age was 60 yrs (range 18–88) and most pts were white (66.2%) males (62.0%). PFS was not statistically different between ripretinib and sunitinib in the Ex11 ITT (hazard ratio [HR] 0.88, 95% CI 0.66, 1.16; P = 0.36; median 8.3 vs 7.0 mos) or in the AP populations (HR 1.05, 95% CI 0.82, 1.33; P = 0.72; median 8.0 vs 8.3 mos). ORR was numerically higher for ripretinib vs sunitinib in the Ex11 ITT (23.9% vs 14.6%; difference 9.3%, 95% CI 0.7, 17.8; nominal P = 0.03) and AP ITT populations (21.7% vs 17.6%; difference 4.2%, 95% CI −3.2, 11.5; nominal P = 0.27). OS data was highly immature; median OS was not reached in either arm. Fewer pts in the ripretinib arm experienced Grade 3-4 (G3-4) treatment-emergent adverse events (TEAEs) vs sunitinib (41.3% vs 65.6%). Among G3-4 TEAEs with a difference ≥5% between arms, ripretinib had fewer events vs sunitinib (hypertension [8.5% vs 26.7%], palmar-plantar erythrodysesthesia [1.3% vs 10.0%], neutropenia [0% vs 6.3%], and neutrophil count decreased [0% vs 7.2%]). Conclusions: The PFS in both arms was longer than PFS achieved by sunitinib in its pivotal phase 3 trial. While the PFS for ripretinib did not meet the primary endpoint of superiority vs sunitinib, meaningful clinical activity and fewer G3-4 TEAEs were observed in pts with advanced GIST treated with ripretinib after imatinib failure. Clinical trial information: NCT03673501.

Priorities and preferences of advanced soft tissue sarcoma patients starting palliative chemotherapy: baseline results from the HOLISTIC study

INTRODUCTION

Palliative chemotherapy is the principal treatment of patients with advanced soft tissue sarcomas (STS); however prognosis is limited (median overall survival 12-19 months). In this setting, patient values and priorities are central to personalised treatment decisions.

PATIENTS AND METHODS

The prospective HOLISTIC study was conducted in the UK and the Netherlands assessing health-related quality of life in STS patients receiving palliative chemotherapy. Participants completed a questionnaire before starting chemotherapy, including attitudes towards quality of life (QoL) versus length of life (LoL), decisional control preferences, and decisional conflict. Chi-square and Fisher's exact tests were used to evaluate associations between patient characteristics and preferences.

RESULTS

One hundred and thirty-seven patients with advanced STS participated (UK: n = 72, the Netherlands: n = 65). Median age was 62 (27-79) years. Preference for extended LoL (n = 66, 48%) was slightly more common than preference for QoL (n = 56, 41%); 12 patients (9%) valued LoL and QoL equally (missing: n = 3). Younger patients (age <40 years) prioritised LoL, whereas two-thirds of older patients (aged ≥65 years) felt that QoL was equally or more important than LoL (P = 0.020). Decisional conflict was most common in patients who prioritised QoL (P = 0.024). Most patients preferred an active (n = 45, 33%) or collaborative (n = 59, 44%) role in treatment decisions. Gender, performance status, and country were significantly associated with preferred role. Concordance between preferred and actual role in chemotherapy decision was high (n = 104, 76%).

CONCLUSIONS

Heterogeneous priorities and preferences among advanced STS patients support personalised decisions about palliative treatment. Considering individual differences during treatment discussions may enhance communication and optimise patient-centred care.

Beyond the Driver Mutation: Immunotherapies in Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are a subtype of soft tissue sarcoma (STS), and have become a concept of oncogenic addiction and targeted therapies.The large majority of these tumors develop after a mutation in KIT or platelet derived growth factor receptor α (PDGFRα), resulting in uncontrolled proliferation. GISTs are highly sensitive to imatinib. GISTs are immune infiltrated tumors with a predominance of tumor-associated macrophages (TAMs) and T-cells, including many CD8+ T-cells, whose numbers are prognostic. The genomic expression profile is that of an inhibited Th1 response and the presence of tertiary lymphoid structures and B cell signatures, which are known as predictive to response to ICI. However, the microtumoral environment has immunosuppressive attributes, with immunosuppressive M2 macrophages, overexpression of indoleamine 2,3-dioxygenase (IDO) or PD-L1, and loss of major histocompatibility complex type 1. In addition to inhibiting the KIT oncogene, imatinib appears to act by promoting cytotoxic T-cell activity, interacting with natural killer cells, and inhibiting the expression of PD-L1. Paradoxically, imatinib also appears to induce M2 polarization of macrophages. There have been few immunotherapy trials with anti-CTLA-4 or anti-PD-L1drugs and available clinical data are not very promising. Based on this comprehensive analysis of TME, we believe three immunotherapeutic strategies must be underlined in GIST. First, patients included in clinical trials must be better selected, based on the identified driver mutation (such as PDGFRα D842V mutation), the presence of tertiary lymphoid structures (TLS) or PD-L1 expression. Moreover, innovative immunotherapeutic agents also provide great interest in GIST, and there is a strong rationale for exploring IDO targeting after disease progression during imatinib therapy. Finally and most importantly, there is a strong rationale to combine of c-kit inhibition with immune checkpoint inhibitors.

Epithelioid hemangioendothelioma, an ultra-rare cancer: a consensus paper from the community of experts

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, translocated, vascular sarcoma. EHE clinical behavior is variable, ranging from that of a low-grade malignancy to that of a high-grade sarcoma and it is marked by a high propensity for systemic involvement. No active systemic agents are currently approved specifically for EHE, which is typically refractory to the antitumor drugs used in sarcomas. The degree of uncertainty in selecting the most appropriate therapy for EHE patients and the lack of guidelines on the clinical management of the disease make the adoption of new treatments inconsistent across the world, resulting in suboptimal outcomes for many EHE patients. To address the shortcoming, a global consensus meeting was organized in December 2020 under the umbrella of the European Society for Medical Oncology (ESMO) involving >80 experts from several disciplines from Europe, North America and Asia, together with a patient representative from the EHE Group, a global, disease-specific patient advocacy group, and Sarcoma Patient EuroNet (SPAEN). The meeting was aimed at defining, by consensus, evidence-based best practices for the optimal approach to primary and metastatic EHE. The consensus achieved during that meeting is the subject of the present publication.

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This consensus paper provides key recommendations on the management of epithelioid hemangioendothelioma (EHE).

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Recommendations followed a consensus meeting between experts and a representative of the EHE advocacy group and SPAEN.

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Authorship includes a multidisciplinary group of experts from different institutions from Europe, North America and Asia.

Phase (Ph) 1b/2 evaluation of olaratumab in combination with gemcitabine and docetaxel in advanced soft tissue sarcoma (STS)

11517

Background: Doxorubicin (doxo) remains standard first-line therapy for advanced STS. Doxo in combination with olaratumab (O) demonstrated superior clinical activity compared to doxo alone in a Ph 2 trial (NCT01185964), although this was not confirmed in the subsequent Ph 3 trial (NCT02451943). Gemcitabine (G) plus docetaxel (D) is a second line therapy for advanced STS. Here, we report a concurrent Ph 2 study that explored a second-line addition of O to G and D for advanced STS (ANNOUNCE 2 NCT02659020). Methods: Adult patients (pts) with unresectable locally advanced or metastatic STS, ≤ 2 prior lines of systemic therapy, and ECOG PS 0-1 were eligible. Pts were enrolled from 2 cohorts: O-naïve and O-pretreated. In both cohorts, pts were randomized 1:1 to either O, G plus D or placebo (PBO), G plus D. Pts received 21-day cycles of O (20 mg/ kg cycle 1 and 15 mg/kg other cycles, day (d) 1 and d8), G (900 mg/m2, d1 and d8) and D (75 mg/m2, d8). Pts continued treatment until progression, toxicity, or withdrawal. Randomization was stratified by histology (leiomyosarcoma [LMS] vs non-LMS), prior systemic therapy, ECOG PS, and prior pelvic radiation. The primary objective was overall survival (OS) in the O-naïve population using an alpha level of 0.20. Secondary endpoints included OS (O-pretreated) and other efficacy parameters, as well as safety and pharmacokinetics (PK). Results: 167 pts were enrolled in the O-naïve cohort and 89 pts in the O-pretreated cohort. Baseline patient characteristics were well balanced. OS for O-naïve pts was 16.8 vs 18.0 months (m) (hazard ratio [HR] = 0.95, 95% CI: 0.64-1.40; p = 0.78) for the investigational vs control arm, respectively. Other efficacy outcomes are presented in the table. Safety was manageable across treatment arms. PK parameter estimates for O were consistent with previous studies. Conclusions: There was no statistically significant difference in OS between the two arms in the O-naïve population. However, while not statistically significant, the combination of O, G and D demonstrated favorable OS in the O-pretreated cohort, and PFS and objective response rate (ORR) in both cohorts. For O-naïve pts, a clinically meaningful progression-free survival (PFS) improvement was observed. Further investigations in specific histological subtypes are ongoing. Clinical trial information: NCT02659020. [Table: see text]

Results of the phase 1b soft-tissue sarcoma (STS) portion of the global randomized, double-blind, placebo-controlled study of tazemetostat (TAZ) plus doxorubicin (DOX) as frontline therapy for advanced epithelioid sarcoma (ES)

11563

Background: ES is a rare, aggressive subtype of STS for which cytotoxic chemotherapy has limited effectiveness. TAZ, an FDA-approved EZH2 inhibitor, has shown single-agent clinical activity and a favorable safety profile in patients with metastatic or locally advanced ES. In preclinical studies, TAZ has shown synergistic antitumor activity with DOX, which is often used as frontline treatment for STS. Here, we present results of the phase 1b study (NCT04204941), designed to assess the recommended phase 3 dose (RP3D), safety, and efficacy of TAZ + DOX in patients with advanced STS. Methods: The open-label, phase 1b portion of this study enrolled adult patients with previously untreated advanced STS. A standard 3 + 3 design was used to assess TAZ 400 mg, 600 mg, and 800 mg orally twice daily in combination with DOX (75 mg/m2 intravenously on day 1 of each cycle, for up to 6 cycles) as frontline therapy. Dose-limiting toxicities (DLTs) were predefined in the protocol. The RP3D of TAZ was determined by Scientific Review Committee review of the safety and pharmacokinetic data from the phase 1b trial, with a target DLT rate of < 33%. Results: As of February 1, 2021, 16 patients are enrolled, including 2 with ES; 10 are still receiving TAZ + DOX and 6 have discontinued (5 due to disease progression, 1 due to patient withdrawal). The median age was 49.5 years (range, 29–82) and all had unresectable STS. Median (range) time on treatment was 13 (0.1–51.1+) weeks across all dose levels evaluated. Two DLTs, both of febrile neutropenia, were observed, one in the TAZ 600 mg + DOX cohort (n = 1/6, 17%), and one in the TAZ 800 mg + DOX cohort (n = 1/3, 33%). When used in combination with DOX, the RP3D of TAZ was 800 mg. Grade 3 or 4 treatment-related treatment-emergent adverse events (TR-TEAEs) occurred in 13/16 (81.3%) patients. The most common (≥ 20%) TR-TEAEs were neutropenia (n = 11, 69%), anemia (n = 10, 63%), fatigue (n = 10, 63%), stomatitis (n = 9, 56%), nausea (n = 8, 50%), febrile neutropenia (n = 7, 44%), constipation (n = 6, 38%), vomiting (n = 6, 38%), and decreased appetite (n = 5, 31%). TR-TEAEs were defined as attributable to either study agent. Conclusions: The combination of TAZ + DOX was generally well tolerated in this dose finding study in patients with advanced STS. The RP3D to be tested in the phase 3 randomized, double blind, placebo controlled study is TAZ 800 mg twice daily + DOX. The safety profile of this combination is consistent with the respective safety information for TAZ and for DOX. The TR-TEAEs include known toxicities of DOX or TAZ. Further comparison with DOX + placebo in the phase 3 trial will aid in assessing efficacy and safety of the combination of TAZ + DOX. The global phase 3 confirmatory trial will enroll patients with ES who have unresectable disease and have had no prior systemic therapy. Clinical trial information: NCT04204941.

Intra-patient dose escalation (IPDE) of ripretinib after disease progression in patients with advanced gastrointestinal stromal tumor (GIST): Analyses from the phase 3 INVICTUS study

11536

Background: Ripretinib is a switch-control tyrosine kinase inhibitor that broadly inhibits KIT and PDGFRA kinase signaling. In the INVICTUS study (NCT03353753), patients with advanced GIST (≥4th-line) receiving ripretinib had a median progression-free survival (mPFS) of 6.3 months vs 1.0 month for patients receiving placebo (HR = 0.15, p <0.0001). In an earlier phase 1 dose escalation study, the maximum tolerated dose was not reached with doses up to 200 mg twice daily (BID). Here, we report efficacy, safety, and pharmacokinetic data for IPDE patients initially randomized to ripretinib from the phase 3 INVICTUS study based on data as of 10 Aug 2020. Methods: A total of 129 patients were randomized 2:1 to ripretinib 150 mg once daily (QD; n = 85) or placebo (n = 44). Patients receiving ripretinib 150 mg QD who had progressive disease (PD) as assessed by blinded independent central review (BICR) using mRECIST were given the option for IPDE to 150 mg BID. Tumor response assessments were performed every 28 days for 4 cycles and every 56 days thereafter (including after IPDE). The primary endpoint was PFS. For this exploratory analysis, PFS1 for IPDE patients was defined as the time from randomization to PD; PFS2 for IPDE patients was the time from the first dose of ripretinib 150 mg BID to PD or death. PFS1 and PFS2 were based on BICR. Results: Of 85 patients treated with ripretinib 150 mg QD, 43 patients with BICR PD dose escalated to 150 mg BID. Baseline characteristics of IPDE patients at time of study entry were similar to those observed in the original ripretinib QD arm and similar to the 22 patients with BICR PD who either remained on 150 mg QD or discontinued treatment. IPDE patients had a mPFS1 of 4.6 months (95% CI, 2.7–6.4) and a mPFS2 of 3.7 months (95% CI, 3.1–5.3); mPFS2/mPFS1=80%. The IPDE dosing period was well tolerated without the emergence of new safety concerns. The most common new or worsening (unchanged or improving grades not included) treatment-emergent adverse event (TEAE) for IPDE patients during the BID period was abdominal pain (30.2% all grades and 7% Grade 3–4 vs 41.9% and 4.7% in QD period, respectively). The most common Grade 3–4 TEAE in the BID period was anemia (14% vs 2.3% in QD period). IPDE from QD to BID resulted in an approximately 2-fold increase in the steady state trough concentration. Conclusions: Similar to the phase 1 study wherein IPDE to 150 mg BID following PD provided clinical benefit with a mPFS1 of 5.5 months and mPFS2 of 4.6 months (mPFS2/mPFS1=84%) for patients with ≥4th-line GIST, these analyses from INVICTUS indicate that IPDE to ripretinib 150 mg BID can also provide additional meaningful clinical benefit and a similar tolerability profile to the 150 mg QD regimen for patients with ≥4th-line GIST that progressed following treatment with ripretinib 150 mg QD. Clinical trial information: NCT03353753.

A comprehensive, contemporary assessment of the association between hepatosteatosis and coronary artery calcium scoring

Funding Acknowledgements

Type of funding sources: None.

onbehalf

Liverpool Multiparametric Imaging Collaboration

Background

Coronary artery calcium (CAC) score is a well-established technique for stratifying an individual’s cardiovascular disease (CVD) risk. Several well-established registries have incorporated CAC scoring into CVD risk prediction models to enhance accuracy. Hepatosteatosis (HS) has been shown to be an independent predictor of CVD events and can be measured on non-contrast computed tomography (CT). We sought to undertake a contemporary, comprehensive assessment of the influence of HS on CAC score alongside traditional CVD risk factors. In patients with HS it may be beneficial to offer routine CAC screening to evaluate CVD risk to enhance opportunities for earlier primary prevention strategies.

Methods

We performed a retrospective, observational analysis at a high-volume cardiac CT centre analysing consecutive CT coronary angiography (CTCA) studies. All patients referred for investigation of chest pain over a 28-month period (June 2014 to November 2016) were included. Patients with established CVD were excluded. The cardiac findings were reported by a cardiologist and retrospectively analysed by two independent radiologists for the presence of HS. Those with CAC of zero and those with CAC greater than zero were compared for demographic and cardiac risks. A multivariate analysis comparing the risk factors was performed to adjust for the presence of established risk factors. A binomial logistic regression model was developed to assess the association between the presence of HS and increasing strata of CAC.

Results

In total there were 1499 patients referred for CTCA without prior evidence of CVD. The assessment of HS was completed in 1195 (79.7%) and CAC score was performed in 1103 (92.3%). There were 466 with CVD and 637 without CVD. The prevalence of HS was significantly higher in those with CVD versus those without CVD on CTCA (51.3% versus 39.9%, p = 0.007). Male sex (50.7% versus 36.1% p= &lt;0.001), age (59.4 ± 13.7 versus 48.1 ± 13.6, p= &lt;0.001) and diabetes (12.4% versus 6.9%, p = 0.04) were also significantly higher in the CAC group compared to the CAC score of zero.

HS was associated with increasing strata of CAC score compared with CAC of zero (CAC score 1-100 OR1.47, p = 0.01, CAC score 101-400 OR:1.68, p = 0.02, CAC score &gt;400 OR 1.42, p = 0.14). This association became non-significant in the highest strata of CAC score.

Conclusion

We found a significant association between the increasing age, male sex, diabetes and HS with the presence of CAC. HS was also associated with a more severe phenotype of CVD based on the multinomial logistic regression model. Although the association reduced for the highest strata of CAC (CAC score &gt;400) this likely reflects the overall low numbers of patients within this group and is likely a type II error.

Based on these findings it may be appropriate to offer routine CVD risk stratification techniques in all those diagnosed with HS.

Diagnosis and management of tropomyosin receptor kinase (TRK) fusion sarcomas: expert recommendations from the World Sarcoma Network

Sarcomas are a heterogeneous group of malignancies with mesenchymal lineage differentiation. The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions as tissue-agnostic oncogenic drivers has led to new personalized therapies for a subset of patients with sarcoma in the form of tropomyosin receptor kinase (TRK) inhibitors. NTRK gene rearrangements and fusion transcripts can be detected with different molecular pathology techniques, while TRK protein expression can be demonstrated with immunohistochemistry. The rarity and diagnostic complexity of NTRK gene fusions raise a number of questions and challenges for clinicians. To address these challenges, the World Sarcoma Network convened two meetings of expert adult oncologists and pathologists and subsequently developed this article to provide practical guidance on the management of patients with sarcoma harboring NTRK gene fusions. We propose a diagnostic strategy that considers disease stage and histologic and molecular subtypes to facilitate routine testing for TRK expression and subsequent testing for NTRK gene fusions.

The Activity of Chemotherapy in Inflammatory Myofibroblastic Tumors: A Multicenter, European Retrospective Case Series Analysis

BACKGROUND

This study aimed to review the activity of cytotoxic chemotherapy in patients with inflammatory myofibroblastic tumors (IMTs) treated at nine European sarcoma reference centers.

MATERIALS AND METHODS

Patients of any age, with histologically proven IMT, treated with anthracycline-based methotrexate plus/minus vinorelbine/vinblastine (MTX-V) or other chemotherapeutic regimens between 1996 and 2018 were retrospectively reviewed. Diagnosis was confirmed at the local level by an expert pathologist. Response was retrospectively assessed by local investigators by RECIST v1.1. Progression-free survival (PFS), relapse-free survival (RFS), and overall survival (OS) were computed by Kaplan-Meier method.

RESULTS

Thirty-eight patients were included. Twenty-five patients (8 localized, 17 advanced disease) received an anthracycline-based regimen; 21 were evaluable for response. Overall response rate (ORR) was 10/21 (47.6%). At a 70.8-month median follow-up (FU), median RFS and median OS were not reached (NR) in patients with localized disease; median PFS and median OS were 6.3 (interquartile range [IQR]: 1.9-13.4) and 21.2 (IQR: 7.7-40.7) months in patients with advanced disease. Thirteen patients received MTX-V (4 localized, 9 advanced disease), all evaluable for response. ORR was 7/13 (53.8%). At a 56.6-month median FU, median RFS and median OS were 42.5 (IQR: 12.9-61.2) months and NR (no death events) in patients with localized disease, and NR (IQR: 24.9 to NR) and 83.4 months (IQR: 83.4 to NR) in patients with advanced disease. In the "other-regimens group," responses were seen in 3/4 patients treated with oral cyclophosphamide and 1/2 with docetaxel/gemcitabine.

CONCLUSION

Anthracycline-based and MTX-V regimens are very effective in IMT, with a similar ORR in both groups. MTX-V achieved a prolonged disease control. Responses were also seen with oral cyclophosphamide and docetaxel/gemcitabine, but few patients were treated with these schedules.

IMPLICATIONS FOR PRACTICE

Inflammatory myofibroblastic tumor (IMT) is an ultrarare sarcoma with known sensitivity to anaplastic lymphoma kinase (ALK) inhibitors in ALK-fused cases, although ALK inhibitors are not licensed in the disease. The current knowledge on the activity of cytotoxic chemotherapy is limited. This multi-institutional retrospective study on pediatric and adult patients with IMT shows that cytotoxic chemotherapy, and in particular anthracycline-based and methotrexate plus/minus vinorelbine/vinblastine regimens, represents a treatment option and can be considered in IMT patients irrespectively from ALK status. This study provides a benchmark for future studies on new medical therapies.

Cardiac safety of trabectedin monotherapy and in combination with pegylated liposomal doxorubicin in patients with sarcomas and ovarian cancer

11547

Background: Trabectedin (T) is an established option as monotherapy for advanced soft tissue sarcomas (STS; Leiomyosarcomas and Liposarcomas in the USA) and in combination with pegylated liposomal doxorubicin (PLD) for recurrent ovarian cancer (ROC). This retrospective analysis evaluated the cardiac safety profile in over 1500 patients (pts) from clinical trials administering T monotherapy for STS or in combination with PLD (T+PLD) for ROC. Methods: Integrated cardiac safety data was analyzed from ten Phase 2 trials and one Phase 3 trial in STS (T) and two Phase 3 ROC trials (T+PLD). Cardiac-related treatment-emergent adverse events (TEAEs) were summarized using MedDRA terminology and by Kaplan-Meier analysis for time-to-event variables. Subgroup analyses were performed for cardiac-related TEAEs, including any significant decrease in LVEF. Results: Integrated data on T monotherapy included 982 pts (Table). Of these, 110 (11.2%) pts who received ≥1 dose of T experienced a cardiac-related TEAE, including tachycardia (3.1%), palpitations (1.5%), LVEF decrease (1.3%), sinus tachycardia (1.0%), and/or congestive cardiac failure (1.0%). A multivariate analysis revealed factors associated with increased risk to be cardiovascular medical history (risk ratio [RR]: 1.90; 95% CI: 1.24-2.91; p = 0.003) and age > 65 years (RR: 1.78; 95% CI: 1.12,2.83; p = 0.014). Cardiac-related TEAEs were reported in 78 (12.6%) of 619 pts receiving T+PLD (Table). Incidence of cardiac-related TEAEs was greater with T+PLD compared with PLD monotherapy (12.6% vs 5.6%). A multivariate analysis showed that pts were at increased risk for experiencing cardiac-related TEAEs when treated with T+PLD compared to PLD monotherapy (RR: 2.70; 95% CI: 1.75,4.17; p < 0.0001) and when there was a history of prior cardiac medication (RR: 1.88; 95% CI: 1.16,3.05; p = 0.010). Conclusions: Although infrequent, patients receiving T after prior anthracyclines or in combination with PLD are at risk for cardiac dysfunction, and appropriate clinical awareness and monitoring is encouraged to optimize patient outcomes. [Table: see text]

Role of adjuvant imatinib dose in radically resected GIST harboring KIT exon 9 mutations

11533

Background: Gastrointestinal stromal tumors (GIST) with a driver mutation in KIT exon 9 (Ex9) represent about 10% of all newly diagnosed cases. In the metastatic setting, Ex9-mutated GIST patients benefit from higher doses of imatinib (800 mg/day vs standard 400 mg/day). The additional therapeutic benefit from a higher dose of imatinib in the adjuvant setting in this molecular subgroup has not been confirmed. Methods: We retrospectively identified 105 patients (pts) with resected Ex9-mutated GIST treated with adjuvant imatinib (800 mg/day or 400 mg/day) in 15 different European centers. Disease-Free Survival (DFS) and Imatinib Failure-Free Survival (IFFS) were calculated and analyzed according to the daily dose of imatinib and relevant clinical and pathological variables. Kaplan–Meier curves were used to estimate survival in univariate analyses, and the log-rank test was used to compare the groups. Hazard Ratios (HR) with 95% confidence intervals (CI) were calculated using a univariable Cox model. A multivariate Cox regression model was also performed. Results: Of the 105 pts who met the inclusion criteria, 69 (65.7%) were treated with 400 mg/day and 36 (34.3%) with 800 mg/day. The risk score (AFIP-Miettinen criteria) between the two dose groups was not statistically different (P = 0.29). Median DFS was 73.0 months (mo) in the 400 mg/day group and 61.9 mo in the 800 mg/day group (HR = 0.82, 95% CI: 0.47-1.47; P = 0.50). Median IFFS was 156.8 mo in the 400/day mg group and 117.4 mo in the 800 mg/day group (HR = 0.66, 95% CI: 0.34-1.29; P = 0.19). In a multivariable analysis, the variables statistically associated with DFS were mitotic count, the longest tumor diameter and the duration of adjuvant therapy. Mitotic count and the duration of adjuvant therapy were also associated with IFFS. Importantly, the daily imatinib dose was not associated with survival in either analysis (Table). Conclusions: This is the largest reported cohort of pts with Ex9-mutated GIST treated with either the 400 mg/day or the 800 mg/day dose of adjuvant imatinib. Although retrospective in nature, the data confirm the prognostic value of mitotic count and suggest that patients with Ex9-mutated GIST derive no additional survival benefit from the 800 mg/day dose. [Table: see text]

Irinotecan and temozolomide upfront and in relapsed Ewing sarcoma: A translational study on MGMT (O6-methylguanine–DNA methyltransferase) and ABCG2 (MGMTLiberati)

e23564

Background: Activity of temozolomide (TEM) and irinotecan (IRI) in recurrent Ewing sarcoma (EWS) was demonstrated. Few data are available on TEMIRI use upfront. Biological predictive factors are lacking. Methods: This multi-institutional retrospective study (NCT03542097) included 59 patients with EWS. 8 patients with very high risk (HR) EWS (multivisceral ± bone marrow) received TEMIRI (TEM 100 mg/m2/day oral, and IRI 40 mg/m2/day intravenous, days 1-5, every 21 days) upfront, 51 patients after relapse (28% in 1st line, 72% ≥ 2nd line). Overall response rate (ORR: CR+PR), SD, and PD, progression-free (PFS) and overall survival (OS) were assessed. The relationship between pre-treatment expression of MGMT and ABCG2 (when FFPE tissue available) with ORR, PFS and OS was evaluated. Results: Median age was 27 years (range 4-62 years): 47 patients (80%) were adults (≥18 years), 35 (61%) had ECOG 0 and 42 (71%) presented with multivisceral disease (+ bone marrow in 5). MGMT was positive in 16/30 (53%), ABCG2 in 4/33 (12%). ORR for upfront TEMIRI (n = 8) was 50% (CR + PR = 1 + 3), with SD 50%, while in recurrent EWS (n = 49, 2 patients no measurable by RECIST) ORR was 31% (CR + PR = 4 + 11), SD 38%, and PD 31%. A better ORR was observed in adult (p = 0.008) & ECOG 0 (p = 0.001) patients; MGMT & ABCG2 expression did not influence ORR. 6-mos PFS was 87% after TEMIRI upfront, 43% at recurrence (p = 0.06), and 65% vs 28% (p = 0.02) for ECOG 0 vs ECOG 1-2, respectively. 6-mos PFS was 62% in MGMT+ vs 33% in MGMT- (p = 0.4) and 75% in ABCG2+ vs 50% in ABCG2- (p = 0.7). Median time to progression (TTP) with upfront TEMIRI was 9 months (range 5-28 months), with 1 patient with ongoing CR at 56 months; median TTP at relapse was 3 months (1-29 months). MGMT and ABCG2 expression did not influence 1-yr OS, whereas ECOG (0 vs 1-2) did (88% vs 31% p < 0.001). Grade 3-4 diarrhea, neutropenia, and thrombocytopenia incidence was < 5%, 1 patient with recurrent kidney EWS died of acute liver failure. Conclusions: TEMIRI showed promising activity in a very unfavorable cohort of EWS patients, with manageable toxicity. Performance status correlated with 6-month PFS & OS whereas MGMT & ABCG2 did not. Clinical trial information: NCT03542097 .

A phase Ib/II study of olutasidenib in patients with relapsed/refractory IDH1 mutant solid tumors: Safety and efficacy as single agent

e16643

Background: Isocitrate dehydrogenase 1 mutations (mIDH1) are present in a variety of solid tumors resulting in production and accumulation of (R)-2-hydroxyglutarate causing DNA hypermethylation and promoting tumorigenesis. Olutasidenib is an oral, potent and selective inhibitor of mutated IDH1 protein. We report preliminary results from the ongoing, first-in-human, Phase 1, open-label, single-arm study of olutasidenib in non-CNS solid tumors. Methods: Patients with advanced relapsed/refractory (R/R) mIDH1 solid tumors received olutasidenib 150 mg BID, orally. Following a dose confirmation cohort (Phase 1b), patients with intrahepatic cholangiocarcinoma (IHCC), chondrosarcoma (CS), or unspecified mIDH1 solid tumors (Other) were enrolled in a Phase 2 efficacy evaluation (NCT: 03684811). Results: As of 31-Oct-2019, 44 patients with relapsed or refractory mIDH1 solid tumors were treated with olutasidenib. Diagnosis included: IHCC (n = 26), CS (n = 13), and Other (n = 5). The median age was 58 years (range: 29-81) and 43% were male. Median number of prior treatments was 2 (1-10). mIDH1 status was locally determined (IHC, NGS or PCR): R132C (61%), R132G (7%), R132S (7%), R132H (2%), R132L (2%), Others (2%) & unspecified (18%). Fourteen patients discontinued treatment (disease progression [n = 6; 3 IHCC, 2 CS, 1 Other], AE [n = 4; 3 IHCC, 1 CS], PI decision [n = 3; IHCC] & withdraw consent [n = 1; IHCC]). Treatment emergent adverse events (all grades, regardless of attribution) that occurred in > 15% of pts were: nausea (43%), fatigue (25%), decreased appetite (22%), AST increase (18%), ALT increase (16%), and constipation (16%). No protocol-defined DLTs occurred. Best responses by tumor type are shown in the table. Conclusions: Single agent olutasidenib at 150 mg BID demonstrates acceptable safety and tolerability with preliminary clinical activity in patients with R/R mIDH1 solid tumors. Updated safety and clinical activity, as well as exploratory evaluations of PK/PD will be provided. Clinical trial information: 03684811 . [Table: see text]

Efficacy and tolerability of trabectedin in elderly patients with sarcoma: subgroup analysis from a phase III, randomized controlled study of trabectedin or dacarbazine in patients with advanced liposarcoma or leiomyosarcoma

Background

Treatment options for soft tissue sarcoma (STS) patients aged ≥65 years (elderly) can be limited by concerns regarding the increased risk of toxicity associated with standard systemic therapies. Trabectedin has demonstrated improved disease control in a phase III trial (ET743-SAR-3007) of patients with advanced liposarcoma or leiomyosarcoma after failure of anthracycline-based chemotherapy. Since previous retrospective analyses have suggested that trabectedin has similar safety and efficacy outcomes regardless of patient age, we carried out a subgroup analysis of the safety and efficacy observed in elderly patients enrolled in this trial.

Patients and methods

Patients were randomized 2 : 1 to trabectedin (n = 384) or dacarbazine (n = 193) administered intravenously every-3-weeks. The primary end point was overall survival (OS); secondary end points were progression-free survival (PFS), time-to-progression, objective response rate (ORR), duration of response, symptom severity, and safety. A post hoc analysis was conducted in the elderly patient subgroup.

Results

Among 131 (trabectedin = 94; dacarbazine = 37) elderly patients, disease characteristics were well-balanced and consistent with those of the total study population. Treatment exposure was longer in patients treated with trabectedin versus dacarbazine (median four versus two cycles, respectively), with a significantly higher proportion receiving prolonged therapy (≥6 cycles) in the trabectedin arm (43% versus 23%, respectively; P = 0.04). Elderly patients treated with trabectedin showed significantly improved PFS [4.9 versus 1.5 months, respectively; hazard ratio (HR)=0.40; P = 0.0002] but no statistically significant improvement in OS (15.1 versus 8.0 months, respectively; HR = 0.72; P = 0.18) or ORR (9% versus 3%, respectively; P = 0.43). The safety profile for elderly trabectedin-treated patients was comparable to that of the overall trabectedin-treated study population.

Conclusions

This subgroup analysis of the elderly population of ET743-SAR-3007 suggests that elderly patients with STS and good performance status can expect clinical benefit from trabectedin similar to that observed in younger patients.

Trial registration

www.clinicaltrials.gov, NCT01343277.

The adequacy of tissue microarrays in the assessment of inter- and intra-tumoural heterogeneity of infiltrating lymphocyte burden in leiomyosarcoma

The characterisation and clinical relevance of tumour-infiltrating lymphocytes (TILs) in leiomyosarcoma (LMS), a subtype of soft tissue sarcoma that exhibits histological heterogeneity, is not established. The use of tissue microarrays (TMA) in studies that profile TIL burden is attractive but given the potential for intra-tumoural heterogeneity to introduce sampling errors, the adequacy of this approach is undetermined. In this study, we assessed the histological inter- and intra-tumoural heterogeneity in TIL burden within a retrospective cohort of primary LMS specimens. Using a virtual TMA approach, we also analysed the optimal number of TMA cores required to provide an accurate representation of TIL burden in a full tissue section. We establish that LMS have generally low and spatially homogenous TIL burdens, although a small proportion exhibit higher levels and more heterogeneous distribution of TILs. We show that a conventional and practical number (e.g. ≤3) of TMA cores is adequate for correct ordinal categorisation of tumours with high or low TIL burden, but that many more cores (≥11) are required to accurately estimate absolute TIL numbers. Our findings provide a benchmark for the design of future studies aiming to define the clinical relevance of the immune microenvironments of LMS and other sarcoma subtypes.

Embryonal and Alveolar Rhabdomyosarcoma in Adults: Real-Life Data From a Tertiary Sarcoma Centre

AIMS

Embryonal and alveolar rhabdomyosarcoma (ERMS, ARMS) are subtypes of RMS that mainly occur in children, with relatively good outcomes. The incidence in adults is extremely low and survival is significantly worse compared with children. Data are scarce and literature generally combines all RMS subtypes, including pleomorphic RMS, which primarily occurs in adults and behaves more like undifferentiated pleomorphic sarcoma. The aim of this study was to evaluate patient and tumour characteristics, outcome and prognostic factors in adult patients with ERMS and ARMS.

MATERIALS AND METHODS

All adult (18 years or older) ERMS and ARMS patients (presenting 1990-2016) were identified from a prospectively maintained database and were included in this analysis.

RESULTS

Overall, 66 patients were included (42 men, 24 women). The median age at presentation was 28 years (range 18-71). The median overall survival for all ARMS (n = 42) and ERMS (n = 24) patients was 18 months, with a 5-year overall survival rate of 27%. Patients presenting with localised disease (n = 38, 58%) and metastatic disease (n = 25, 42%), had a 5-year overall survival rate of 36% and 11%, respectively. In univariate analysis we found alveolar subtype, fusion gene positivity, infiltrative tumour and metastatic presentation to be negative prognostic factors.

CONCLUSION

Survival in adult ERMS and ARMS patients is poor and the current data may be useful in the design of trials with novel agents. Ideally, paediatric and adult oncologists should set up trials together to get a better understanding of biological, genetic and clinically relevant factors in this disease.

ANNOUNCE: A randomized, placebo (PBO)-controlled, double-blind, phase (Ph) III trial of doxorubicin (dox) + olaratumab versus dox + PBO in patients (pts) with advanced soft tissue sarcomas (STS)

LBA3

Background: Dox is standard therapy in STS. In a Ph 2 trial, olaratumab (a human IgG1 antibody targeting PDGFRα) + dox improved overall survival (OS) and progression-free survival (PFS) vs dox. ANNOUNCE aimed to confirm the OS benefit in advanced STS. Methods: Adult pts with unresectable locally advanced or metastatic STS, anthracycline-naïve, and ECOG PS 0-1 were eligible. Pts were randomized 1:1 to olaratumab (20mg/kg Cycle 1, 15mg/kg subsequent cycles) or PBO on Days 1 and 8 of each 21-day cycle combined with dox (75mg/m2) on Day 1 for up to 8 cycles. After 8 cycles, pts with disease control continued olaratumab or PBO until progression or toxicity. Randomization was stratified by histology, prior systemic therapy, ECOG PS, and geographic region. Dexrazoxane use was allowed to mitigate dox-related cardiotoxicity. Primary endpoints were OS in the intent-to-treat (ITT) population and/or leiomyosarcoma (LMS) subset of the ITT population; the study was designed to be positive if either primary endpoint was met. Secondary endpoints included PFS, response/disease control rates, safety, and pharmacokinetics. Results: 509 pts were randomized: 258 in the investigational and 251 in the control arm. Baseline pt characteristics were well balanced. Dexrazoxane was received by 63.0% vs 65.1% of pts (investigational vs control arm, respectively, for all data). In the ITT population, median OS was 20.4 vs 19.8 months (m) (HR=1.05, 95% CI: 0.84-1.30; p = 0.69) and was 21.6 vs 21.9 m in LMS pts (HR=0.95, 95% CI: 0.69-1.31; p = 0.76). Median PFS was lower in the investigational arm in the ITT population (5.4 vs 6.8 m; HR=1.23, 95% CI: 1.01-1.50; p = 0.04) and in LMS pts (4.3 vs 6.9 m, HR=1.22, 95% CI: 0.92-1.63; p = 0.17). Median dox exposure was 6 vs 7 cycles. Safety was similar between arms. Olaratumab serum concentrations reached levels expected from prior trials. Additional subgroup/biomarker results will be presented. Conclusions: ANNOUNCE did not confirm that olaratumab + dox, followed by olaratumab monotherapy, improves OS over dox in pts with advanced STS. Further analyses are warranted to explore the inconsistent outcomes between the Ph 3 and Ph 2 studies. Clinical trial information: NCT02451943.

Clinical activity of avapritinib in ≥ fourth-line (4L+) and PDGFRA Exon 18 gastrointestinal stromal tumors (GIST)

11022

Background: Targeting oncogenic KIT and PDGFRA mutations revolutionized treatment of patients (pts) with advanced GIST; however, nearly all pts succumb to resistant disease. Avapritinib is a potent and selective kinase inhibitor with broad activity against oncogenic KIT/PDGFRA mutants, including PDGFRA D842V and other primary or secondary resistance mutations. Updated results from the phase 1 NAVIGATOR (NCT02508532) study of avapritinib in pts with advanced GIST are presented. Methods: Adult pts with unresectable PDGFRA D842V or other mutant GIST who progressed on imatinib and ≥ 1 other tyrosine kinase inhibitor (TKI) were treated with oral, daily, continuous avapritinib. Adverse events (AE) and response by mRECIST 1.1 per central radiology were assessed. Safety from the overall population (30-600 mg doses) and efficacy in the response evaluable 4L+ and PDGFRA Exon 18 (Ex 18) populations treated at the MTD (400 mg)/RP2D (300 mg) were analyzed. Results: As of 16 Nov 2018, 237 pts [172 KIT, 62 PDGFRA Ex 18 (56 D842V, 6 non-D842V), 2 PDGFRA N659K, 1 missing] were enrolled including 111 in the 4L+ population (primarily KIT, median 4 prior TKI) and 43 in the Ex 18 population (median 1 prior TKI). The 4L+ ORR was 22% [1 CR, 23 PR (1 pending)], and 52 SD with median duration of response (mDOR) of 10.2 months (95% CI: 7.2-NE). The Ex 18 ORR was 86% [3 CR, 34 PR (1 pending)] and 5 SD; mDOR was not reached (95% CI: 11.3-NE). Most AE were grade 1-2, most commonly nausea (63%), fatigue (58%), anemia (49%), periorbital edema (42%), diarrhea (40%), vomiting (40%), decreased appetite (38%), increased lacrimation (33%), peripheral edema (33%) and memory impairment (most common cognitive AE, 29%). 10% of pts discontinued due to a related AE. Grade 3-4 related AE ≥ 2% were anemia, fatigue, hypophosphatemia, hyperbilirubinemia, neutropenia, and diarrhea. Conclusions: Avapritinib has important clinical activity in pts with advanced GIST who have no effective therapies. The ORR and DOR of avapritinib in 4L+ exceeds that of approved 2nd and 3rd line therapies and shows unprecedented activity in D842V and other Ex 18 mutant PDGFRA GIST. Results suggest avapritinib has the potential to change the treatment paradigm of pts with advanced GIST. Clinical trial information: NCT02508532.

A phase I/II study of pembrolizumab (Pem) and doxorubicin (Dox) in treating patients with metastatic/unresectable sarcoma

11009

Background: Patients with advanced soft tissue sarcomas (STS) treated with single agent Dox have a median progression-free survival (PFS) of 4.6 months (mo) and response rate (RR) of 14%. Dox sensitizes tumors to Pem through calreticulin release and killing of immunosuppressive cells. Thus we hypothesize that combining Dox + Pem will improve patient outcomes. Methods: A phase I/II trial (NCT02888665) evaluating Dox+Pem was designed for Dox naïve STS and select bone sarcomas with a 1° endpoints of safety (CTCAE v4.03) and response rate (RR) by RECIST 1.1. Patients received one “priming” dose of Pem (200mg IV) prior to starting Dox+Pem Q3wks. Dox+Pem was continued for up to 6 cycles, followed by Pem monotherapy for up to 2 years or progression. The phase I portion used a 3+3 design with 2 Dox doses (45 & 75 mg/m2), followed by a Simon 2-stage expansion. A retrospective study of patients treated at our center on non-ifosfamide containing Dox trials (DoxT) was performed in order to compare our observed PFS with a comparable historic population. Results: Treatment was well tolerated; detailed safety data will be presented. No additional cardiac risk was observed. No DLTs were observed during phase I and 75mg/m2 was selected as the phase 2 Dox dose. The study met criteria for expansion to the 2nd stage. Though the planned enrollment was 41, the study closed after 37 as it was clear that the RR (22% , including phase I patients) would not meet the phase 2 RR target of 29%. However, 59% of patients had stable disease (disease control rate = 81%) with tumor regression in a majority of patients. The median PFS on Dox + Pem was 8.1 mo (95% CI: 6.3, 10.8). Patients treated with Dox + Pem had a significantly longer median PFS compared to the DoxT cohort (4.1 mo, 95%CI 3.0 – 6.6, p < 0.001). Conclusions: Dox+Pem is well-tolerated. While this study failed to meet its 1° RR endpoint, a highly significant improvement in PFS was observed compared with historical controls. This is consistent with findings in other cancers, such as head & neck, where improved clinical outcomes were observed without significant increase in RR by RECIST. A randomized trial of Dox +/- Pem should be carefully considered in light of recent negative trials in STS. Clinical trial information: NCT02888665.

SAINT: Results of a phase 1/2 study of safety/efficacy using safe amounts of ipilimumab, nivolumab, and trabectedin as first-line treatment of advanced soft tissue sarcoma

11016

Background: Sarcoma cells are most immunogenic earlier in the disease course and prior to treatment when the immune system can recognize and destroy them. Hypothesis: Immune checkpoint inhibitors would be most effective when given as first line therapy. Methods: This is an IRB-approved dose-seeking Phase 1/2 protocol using defined doses of I (1 mg/kg i.v. q 12 weeks), N (3 mg/kg i.v. q 2 weeks) and escalating doses of T (1.0, 1.2, 1.5 mg/m2 i.v. q 3 weeks), employing the “Cohort of Three” design, followed by a Phase 2 using the MTD of trabectedin. Results: Nine subjects were treated in Phase 1 of the study, and 31 subjects in Phase 2. Safety analysis: at Dose 1: Grade 3 treatment-related adverse events (TRAEs) included fatigue (n = 1), increased TSH (n = 1). At Dose 2, Grade 4 TRAEs included thrombocytopenia with bleeding, DLT (n = 1), increased CK (n = 1); Grade 3 TRAEs included anemia (n = 1), myalgia (n = 1), increased TSH (n = 1), decreased TSH (n = 1), increased AST (n = 1). Efficacy analysis (evaluable patients): At Dose 1: Disease Control Rate (DCR = CR, PR, SD) was 67%, median PFS, 18 weeks; median OS, 50 weeks; At Dose 2: PR (n-1), DCR 60%, median PFS, 24 weeks; median OS, > 46 weeks. At Phase 2, MTD Dose 2 (PUPs): Safety analysis (n = 31): Grade 3 TRAEs included fatigue (n = 2), increased ALT (n = 6), increased AST (n = 4), hypernatremia (n = 1), hyponatremia (n = 1), dehydration (n = 1), rash (n = 1), port cellulitis (n = 1), psoriasis exacerbation (n = 1), increased TSH (n = 1), decreased hemoglobin (n = 2), neutropenia (n = 1). Efficacy analysis (N = 23 evaluable): PR (n-5; 2 UPS, 1 synovial sarcoma, 1 liposarcoma, 1 leiomyosarcoma,), BORR 22%, DCR 96%. Median PFS and OS not yet reached. After 4 treatment cycles, one resected tumor showed 80% necrosis and a greater number (30%) of CD8+ killer T cells, in the TME compared to archived pre-treatment tumor. Conclusions: These data suggest that the SAINT protocol (1) is safe with manageable adverse events, with no additive toxicity, and (2) may control tumor growth. Phase 2 of the study is on-going. Clinical trial information: NCT03138161.

A single-center retrospective study of patients treated with trabectedin (TRB) with long-term follow up

11061

Background: TRB is FDA approved drug for the treatment of liposarcoma (Lipo) and leiomyosarcoma (LMS). The aim of this study was to evaluate potential biomarkers associated with prolonged benefit in patients treated with TRB at our center prior to 2016. Methods: We performed a retrospective search of UW/FHCRC CASIS database to identify patients treated with TRB prior to 2016. Demographic variables and clinical variables (such as histology and treatment) were retrieved. Statistics were performed with R 3.4.1 software. Pairwise Pearson’s correlation was calculated for the # of prior chemotherapy regimens with # of TRB cycles. The Kaplan-Meir method was used to evaluate overall survival (OS). Log-rank test was conducted to compare groups in terms of OS. Results: 145 sarcoma patients treated with TRB were identified with a mean follow up of 5 years (generally on NCT01427582 or NCT01343277). Patients averaged 1.9 prior chemotherapy regimens prior to TRB (range 0-7 regimens) and received an average of 5.6 TRB doses (range 1-25 doses). Subtypes are listed on table. The # of prior regimens was negatively correlated with the # of TRB cycles that patients received (pairwise correlation coefficient = -1.77; p=0.034), suggesting that multiple prior treatment lines either made TRB less tolerable or made sarcoma less sensitive to TRB. The median OS for this heavily treated metastatic population was 0.5 years. However, patients who were able to stay on TRB for more than 5 cycles had a significantly higher OS (p=0.001). While only 23% of patients who received less than 5 cycles of TRB were alive at 5 years (95% CI: 0.15, 0.32), 53% of those who received 5 or more cycles of (95% CI: 0.39, 0.65) were alive at 5 years. Conclusions: TRB may be more effective when administered as an earlier line of therapy. Patients who are able to stay on TRB for a longer duration had a significant improvement in OS. Detailed subset analysis will be presented as will initial findings of our biomarker work. These retrospective data warrant further evaluation. Clinical trial information: NCT01427582 or NCT01343277. [Table: see text]

The SAINT: Initial results of a phase I/II study of safety/efficacy using safe amounts of ipilimumab, nivolumab, and trabectedin as first-line treatment of advanced soft tissue sarcoma

22

Background: Sarcoma cells are most immunogenic at the onset of cancer. Hypothesis: Immune checkpoint inhibitors would be most effective when given as first line therapy. Objectives: (1) To evaluate the safety of ipilimumab (I), a CTLA4 inhibitor, nivolumab (N), a PD-1 inhibitor, and escalating doses of trabectedin (T), a marine-derived natural alkaloid, in advanced soft tissue sarcomas (STS), (2) To investigate the BORR, DCR, PFS and OS, and (3) to correlate response with immune cell trafficking in the tumor microenvironment. Methods: This is an IRB-approved dose-seeking phase 1/2 study using defined doses of I (1 mg/kg IV q 12 weeks), N (3 mg/kg IV q 2 weeks) and escalating doses of T (1.0, 1.3, 1.5 mg/m2 IV q 3 weeks), employing “cohort of three” design, with a Phase 2 component using the MTD of T. Results: Phase 1 safety analysis: At Dose 1: Grade 3 treatment related adverse events (TRAEs): fatigue (n = 1), increased TSH (n = 1). At Dose 2, Grade 4 TRAEs: thrombocytopenia with bleeding, DLT (n = 1), increased CK (n = 1); Grade 3 TRAEs: anemia (n = 1), myalgia (n = 1), increased TSH (n = 1), decreased TSH (n = 1), increased AST (n = 1). At Phase 2, Grade 4 TRAEs: increased CK (n = 1); Grade 3 TRAEs: increased ALT (n = 4), anemia (n = 3) neutropenia (n = 1), portal cellulitis (n = 1). Efficacy analysis: Phase 1 (n = 9): At Dose 1: DCR 67%, median PFS, 18 weeks; median OS, 50 weeks; At Dose 2: PR (n-1, rhabdomyosarcoma), DCR 60%, median PFS, > 42 weeks; median OS, > 47 weeks. Phase 2 (n = 16): PR (n = 3; 1 liposarcoma, 1 leiomyosarcoma, 1UPS); BORR 18.75%, DCR 87.5%, median PFS, > 19 weeks; median OS, > 26 weeks. Surgical resection was undertaken in 1 patient with SD after 4 cycles. The surgical specimen showed 80% necrosis and greater number (30%) of CD8+ killer T cells, 10% PD-L1+ cells in the TME compared to that of archived pre-treatment tumor. Conclusions: Taken together, these data suggest that the SAINT protocol (1) is safe with manageable adverse events, with no additive toxicity, and (2) may control tumor growth. The phase 2 part of the study is on-going. Clinical trial information: NCT03138161.