Clinicopathologic and molecular correlates to neoadjuvant chemotherapy-induced pathologic response in breast angiosarcoma.

Both primary and secondary breast angiosarcoma (AS) are characterized by multifocal presentation and aggressive behavior. Despite multimodality therapy, local and distant relapse rates remain high. Therefore, neoadjuvant chemotherapy (NACT) is employed to improve the R0 resection rates and survival, but its benefits remain controversial. Herein, we investigate pathologic and molecular correlates to NACT-induced histologic response in a group of 29 breast AS, 4 primary and 25 radiation-associated (RA). The two NACT regimens applied were anthracycline- and non-anthracycline-based. The pathologic response grade was defined as: I: ≤ 50%, II: 51%-90%, III: 91%-99%, and IV: 100%. An additional 45 primary AS and 102 RA-AS treated by surgery alone were included for survival comparison. The genomic landscape was analyzed in a subset of cases and compared to a cohort of AS without NACT on a paired tumor-normal targeted DNA NGS platform. All patients were females, with a median age of 31 years in primary AS and 68 years in RA-AS. All surgical margins were negative in NACT group. The NACT response was evenly divided between poor (Grades I-II; n = 15) and good responders (Grades III-IV; n = 14). Mitotic count >10/mm2 was the only factor inversely associated with pathologic response. By targeted NGS, all 10 post-NACT RA-AS demonstrated MYC amplification, while both primary AS harbored KDR mutations. TMB or other genomic alterations did not correlate with pathologic response. All four patients with Grade IV response remained free of disease. The good responders had a significantly better disease-specific survival (p = 0.04). There was no survival difference with NACT status or the NACT regimens applied. However, NACT patients with MYC-amplified tumors showed better disease-free survival (p = 0.04) compared to MYC-amplified patients without NACT. The overall survival of NACT group correlated with size >10 cm (p = 0.02), pathologic response (p = 0.04), and multifocality (p = 0.01) by univariate, while only size >10 cm (p = 0.03) remained significant by multivariate analysis.

Distinct genomic landscapes in radiation-associated angiosarcoma compared with other radiation-associated sarcoma histologies.

MYC amplifications have been frequently detected in radiation (RT)-associated angiosarcomas (ASs) by low-resolution molecular methods. However, large-scale next-generation sequencing (NGS) studies to investigate the genomic landscape of RT-AS are scarce, particularly compared with other RT-associated sarcomas. We performed a detailed comparative genomic investigation of RT-AS versus other RT-associated histotypes, as well as sporadic sarcomas with similar histologies. Our institutional targeted DNA-NGS assay database was searched for RT-associated sarcomas. Clinical outcome data, pathologic diagnosis, and the types and frequencies of genomic alterations, including single nucleotide variants (SNVs) and copy number alterations (CNAs), were analyzed. The cohort consisted of 82 patients, 68 (83%) females and 14 (17%) males, aged 37-88 (mean 64) years. Forty-four RT-ASs (38 from breast) and 38 RT sarcomas of other histologies, including 12 malignant peripheral nerve sheath tumors (RT-MPNSTs), 14 undifferentiated pleomorphic sarcomas (RT-UPSs), and 12 osteosarcomas (RT-OSs), were included. Median time intervals from radiation to initial diagnosis in RT-AS (8.0 years) were significantly lower than those in RT-MPNST and RT-UPS (12.5 and 18.5 years), respectively. Each RT-sarcoma histotype harbored distinct mutations and CNAs. RT-associated AS had more frequent MYC, FLT4, CRKL, HRAS, and KMT2D alterations than sporadic AS (enriched in TP53, KDR, ATM, ATRX), whereas the mutational landscapes of MPNST, UPS, and OS were similar in both RT and non-RT settings. CDKN2A/B deletions and TP53 alterations were infrequent in RT-AS compared with other RT sarcomas. Among RT sarcomas, RT-AS harbored the lowest fraction of genome altered (FGA), while RT-MPNST showed the highest FGA. RT-AS had the lowest insertion:SNV and deletion:SNV ratios, while RT-UPS had the highest. The predominant mutational signatures were associated with errors in DNA repair and replication. In conclusion, RT-AS has a distinct genomic landscape compared with other RT sarcomas and sporadic AS. Potential molecular targets for precision medicine may be histotype-dependent. © 2023 The Pathological Society of Great Britain and Ireland.

The impact of MYC gene amplification on the clinicopathological features and prognosis of radiation-associated angiosarcomas of the breast.

AIMS: Radiation-associated angiosarcomas (RT-ASs) of the breast are rare tumours with a poor prognosis. MYC gene amplification is considered to be the hallmark of RT-AS, and is sometimes used as a diagnostic tool to distinguish it from other radiation-associated vascular lesions. However, a small subset of RT-ASs lacks MYC amplification, and this may be associated with better outcome. Loss of trimethylation at lysine 27 of histone 3 (H3K27me3) expression by immunohistochemistry (IHC) has been recently postulated as an additional diagnostic marker for RT-AS. The aims of this study were to evaluate the impact of MYC amplification as detected by fluorescence in-situ hybridisation and/or next-generation sequencing on clinicopathological features and outcome in a large cohort of RT-ASs, compare outcome with those of radiation-associated sarcomas (RT-Ss) of the breast other than angiosarcoma, and evaluate expression of H3K27me3 IHC in these groups. METHODS AND RESULTS: Eighty-one RT-ASs were identified, including 73 that were MYC-amplified and 8 (10%) that were MYC-non-amplified. MYC-amplified RT-ASs were diagnosed in older patients (median age, 69 years versus 61 years). The 5-year disease-specific survival and 5-year overall survival rates were 56% and 47%, respectively. Older age, larger tumour size, positive margin and MYC amplification were associated with worse prognosis. None of the RT-ASs showed complete loss of H3K27me3 IHC expression. All 18 RT-Ss were MYC-non-amplified, and complete loss of H3K27me3 expression was seen in 2 cases. We found no difference in prognosis between RT-AS and RT-S. CONCLUSIONS: RT-AS of the breast is associated with a poor prognosis. Older age at diagnosis, larger tumour size, positive margin at excision and MYC amplification are associated with worse prognosis.

Prognostic stratification of clinical and molecular epithelioid hemangioendothelioma subsets.

Epithelioid hemangioendothelioma is a low-grade malignant vascular tumor with an intermediate clinical behavior between benign hemangiomas and high-grade angiosarcomas. Pathologic or molecular factors to predict this clinical heterogeneity are not well defined. A WWTR1-CAMTA1 fusion is present in most classic epithelioid hemangioendothelioma, regardless of their clinical behavior, suggesting that additional genetic abnormalities might be responsible in driving a more aggressive biology. A small subset of cases show distinct morphology and are characterized genetically by a YAP1-TFE3 fusion. Two histologic grades have been described in classic epithelioid hemangioendothelioma of the soft tissue. However, proposed criteria do not apply to other clinical presentations and have not been assessed in the YAP1-TFE3 positive tumors. Furthermore, no previous studies have compared the survival of these two molecular subsets. In this study we investigate the clinicopathologic and molecular findings of a large cohort of 93 translocation-positive epithelioid hemangioendothelioma managed at our institution. Patient characteristics, histologic features, treatment outcomes, and genetic abnormalities were investigated and these factors were correlated with overall survival. In 18 patients (15 with WWTR1-CAMTA1 and 3 with YAP1-TFE3) Memorial Sloan Kettering-IMPACT targeted DNA sequencing was performed to identify secondary genetic alterations showing more than half of tumors had a genetic alteration beyond the disease-defining gene fusion. Patients with conventional epithelioid hemangioendothelioma with WWTR1-CAMTA1 fusion had a less favorable outcome compared with the YAP1-TFE3 subset, the 5-year overall survival being 59% versus 86%, respectively. Soft tissue epithelioid hemangioendothelioma were frequently solitary, followed an uneventful clinical course being often managed with curative surgery. Multifocality, pleural involvement, lymph node or distant metastases had a significantly worse outcome. Patients with pleural disease or lymph node metastases had an aggressive clinical course akin to high-grade sarcomas, with 22% and 30%, respectively, alive at 5 years, compared with >70% survival rate in patients lacking these two adverse factors.

Multicentre retrospective study of intravascular large B-cell lymphoma treated at academic institutions within the United States.

Intravascular large B-cell lymphoma (IVLBCL) is a rare entity, with a generally aggressive course that may vary based on geographic presentation. While a United States (US) registry study showed relatively good outcomes with IVLBCL, clinicopathological and treatment data were unavailable. We performed a detailed retrospective review of cases identified at 8 US medical centres, to improve understanding of IVLBCL and inform management. We compiled data retrieved via an Institutional Review Board-approved review of IVLBCL cases identified from 1999 to 2015 at nine academic institutions across the US. We characterized the cohort's clinical status at time of diagnosis, presenting diagnostic and clinical features of the disease, treatment modalities used and overall prognostic data. Our cohort consisted of 54 patients with varying degrees of clinical features. Adjusting for age, better performance status at presentation was associated with increased survival time for the patients diagnosed in vivo (hazard ratio: 2·12, 95% confidence interval 1·28, 3·53). Based on the data we have collected, it would appear that the time interval to diagnosis is a significant contributor to outcomes of patients with IVLBCL.

A Phase I Study of Binimetinib (MEK162) Combined with Pexidartinib (PLX3397) in Patients with Advanced Gastrointestinal Stromal Tumor.

LESSONS LEARNED: The combination of pexidartinib and binimetinib was safe and tolerable and demonstrated encouraging signs of efficacy in two patients with advanced gastrointestinal stromal tumor (GIST) refractory to tyrosine kinase inhibitors (TKIs).Molecular profiling of GISTs at diagnosis and upon progression may provide insight into the mechanisms of response or resistance to targeted therapies.Additional trials are needed to further explore combined KIT and MEK inhibition in treatment-naïve and TKI-refractory patients with advanced GIST. BACKGROUND: Nearly all patients with advanced gastrointestinal stromal tumor (GIST) develop resistance to imatinib, and subsequent treatments have limited efficacy. Dual inhibition of KIT and MAPK pathways has synergistic antitumor activity in preclinical GIST models. METHODS: This was an investigator-initiated, phase I, dose escalation study of the MEK inhibitor binimetinib combined with pexidartinib, a potent inhibitor of CSF1R, KIT, and FLT3, in patients with advanced or metastatic GIST who progressed on imatinib. The primary endpoint was phase II dose determination; secondary endpoints included safety, tolerability, and efficacy. An expansion cohort to further evaluate safety and efficacy was planned. RESULTS: Two patients were treated at dose level one (binimetinib 30 mg b.i.d. and pexidartinib 400 mg every morning and 200 mg every evening), after which the study was terminated by the manufacturer. No dose-limiting toxicities (DLTs) were reported, and treatment was well tolerated. The only grade ≥3 treatment-emergent adverse event (TEAE) was asymptomatic elevated creatine phosphokinase (CPK). Both patients had a best response of stable disease (SD) by RECIST. Progression-free survival (PFS) and overall survival (OS) were 6.1 and 14.6 months, respectively, in one patient with five prior lines of therapy. The second patient with NF1-mutant GIST had a 27% decrease in tumor burden by RECIST and remains on study after 19 months of treatment. CONCLUSION: Pexidartinib combined with binimetinib was tolerable, and meaningful clinical activity was observed in two imatinib-refractory patients.

Diagnosis and management of neuropathies associated with plasma cell dyscrasias.

Neuropathies associated with plasma cell dyscrasias are a major cause of morbidity for patients managed by medical oncologists. Because of similarities in clinical presentation and on nerve conduction studies, identifying the underlying disease leading to a paraproteinemic neuropathy can often be difficult. In addition, the degree of neurologic deficit does not strictly correlate with the extent of abnormalities on common clinical laboratory testing. Fortunately, with increasing understanding into the biologic mechanisms of underlying hematologic diseases, additional biomarkers have recently been developed, thus improving our diagnostic capacity. Neuropathies associated with plasma cells dyscrasias are seen with Monoclonal gammopathy of undetermined significance (MGUS) particularly IgM subtype, followed by IgG and IgA MGUS, multiple myeloma, Waldenström's macroglobulinemia, amyloid, Castleman's disease, and POEMS syndrome. The mechanisms of neuronal injury associated with plasma cell dyscrasia vary based on underlying diagnosis and include malignant infiltration, immune-mediated antibody deposition, or local compression of nerve roots. The polyneuropathies are frequently demyelinating, although axonal and mixed neuropathies can also be seen. As demonstrated by the cases included in this review, patients frequently present with symmetric sensory disturbance, followed by progressive motor weakness. Unfortunately, because of the complexity of diagnostic testing, patients are frequently examined late, often after receiving several ineffective therapies. The aim of this case-based review is to provide clinicians with insight on how to properly recognize these atypical neuropathies and send the appropriate diagnostic work, increasing the likelihood of accurately classify the patient's underlying hematologic disorder.

Histology-specific clinical trial of lenvatinib and pembrolizumab in patients with sarcoma.

PURPOSE: Survival of patients with metastatic sarcoma remains poor, and there is pressing need for new therapies. Most sarcoma subtypes are not responsive to immune checkpoint inhibition alone. Lenvatinib, a multi-receptor tyrosine kinase inhibitor targeting tumor vasculature, has immunomodulatory activity that contributes to its antitumor effects. Therefore we hypothesized that combination of lenvatinib and pembrolizumab would lead to improved clinical outcomes in patients with sarcoma. METHODS: This was an open-label, single-arm study of lenvatinib and pembrolizumab in the following cohorts A: leiomyosarcoma, B: undifferentiated pleomorphic sarcoma (UPS), C: vascular sarcomas (angiosarcoma and epithelioid hemangioendothelioma), D: synovial sarcoma or malignant peripheral nerve sheath tumor (MPNST), and E: bone sarcomas (osteosarcoma and chondrosarcoma). The primary endpoint was best overall response (BOR) rate documented by RECIST v1.1 by 27 weeks in each cohort, with a threshold of ≥2 responses among 10 patients. Secondary endpoints included progression-free survival, overall survival, duration of response and safety. RESULTS: Forty-six patients were evaluable for the primary endpoint which was met in the UPS and MPNST/synovial cohorts (BOR rates by 27 weeks of 25% and 30%,respectively). There were 7 partial responses overall with additional responses noted in angiosarcoma and osteosarcoma. Treatment-related adverse events of any grade, and Grade 3 or higher, occurred in 50/51 (98%) and 29/51 (57%) of patients respectively. CONCLUSIONS: We observed durable responses in MPNST, synovial sarcoma and osteosarcoma. Patients with UPS and angiosarcoma also responded. Further exploration of this approach is warranted to confirm activity and determine optimal dosing schedules.

International Multicenter Retrospective Study From the Ultra-rare Sarcoma Working Group on Low-grade Fibromyxoid Sarcoma, Sclerosing Epithelioid Fibrosarcoma, and Hybrid Forms: Outcome of Primary Localized Disease.

The aim of the study was to report the outcome of primary localized low-grade fibromyxoid sarcoma (LGFMS), sclerosing epithelioid fibrosarcoma (SEF), and hybrid LGFMS/SEF (H-LGFMS/SEF). Patients with primary localized LGFMS, SEF, or H-LGFMS/SEF, surgically treated with curative intent from January 2000 to September 2022, were enrolled from 14 countries and 27 institutions. Pathologic inclusion criteria were predefined by expert pathologists. The primary endpoint was overall survival (OS). Secondary endpoints were crude cumulative incidence (CCI) of local recurrence (LR), CCI of distant metastases (DM), and post-metastases OS (p-OS). Two hundred ninety-four patients (239 LGFMS, 32 SEF, and 23 H-LGFMS/SEF) were identified. At a median(m-) follow-up (FU) of 57.1 months, 12/294 patients died. The 5- and 10-year OS were 99.0% and 95.9% in LGFMS, 86.2% and 67.0% in SEF, and 84.8% and 84.8% in H-LGFMS/SEF, respectively. Predictors of worse OS included pathology, age at surgery, systemic therapy, and radiotherapy. LR developed in 13/294 (4.4%) patients. The observed m-time to LR was 10.7 months. The 5- and 10-yr CCI-LR were 4.7% in LGFMS and 6.6% in SEF, respectively. There were no LR events in H-LGFMS/SEF. The sole predictor of higher risk of LR was histology. DM developed in 23/294 (7.8%) patients. The observed m-time to DM was 28.2 months. The 5- and 10-yr CCI-DM were 1.3% and 2.7% in LGMFS, 29.9% and 57.7% in SEF, 48.9% and 48.9% in H-LGFMS/SEF, respectively. Predictors of higher risk of DM were histology, systemic therapy, and radiotherapy. Primary localized LGFMS treated with complete surgical resection has an excellent prognosis, while about 50% of H-LGFMS/SEF and SEF develop DM within 5 to 10 years. Very long-term FU is needed to understand absolute cure rates.

Histopathologic Grading Is of Prognostic Significance in Primary Angiosarcoma of Breast: Proposal of a Simplified 2-tier Grading System.

Despite a wide spectrum of clinical presentations, including primary or secondary, most angiosarcomas are considered high grade. One exception is primary breast angiosarcoma, where historically, histologic grading has shown to predict outcome using the Rosen 3-tier system. However, more recent studies have challenged this concept suggesting that even in this specific clinical context angiosarcomas should be considered high grade. This study aimed to critically reevaluate the impact of histologic grade in a clinically uniform cohort managed at a single institution using a newly proposed grading system. Our study included 49 primary breast angiosarcomas diagnosed during 1994 to 2022 (median follow-up: 33 mo), classified as low grade (29%), intermediate grade (20%), and high grade (51%), based on mitotic count, extent of solid components, and necrosis. At last follow-up, 22% patients developed locoregional recurrences, 63% distant metastases, and 47% patients died of disease. As patients with low and intermediate-grade angiosarcomas had relatively similar outcomes, our cohort was further analyzed using a 2-tier system (low grade and high grade). Targeted-DNA next-generation sequencing (505 cancer gene panel) performed in 11 cases found KDR mutations in 78% and PIK3CA mutations in 44% of high-grade lesions. Histologic grade, by either 3-tier or 2-tier grading systems, had a strong impact on survival, with the 2-tier system being an independent predictor of disease-specific survival and overall survival. Based on 2-tier system, the 5-year overall survival was 38% for high-grade angiosarcoma and 74% for low-grade angiosarcoma. PIK3CA mutations alone or concurrent with KDR alterations were identified in angiosarcomas with worse prognosis.

Immune-related Adverse Events after Immune Checkpoint Blockade-based Therapy Are Associated with Improved Survival in Advanced Sarcomas.

The association between immune-related AEs (irAE) and outcome in patients with sarcoma is not known. We retrospectively reviewed a cohort of patients with advanced sarcoma treated with immune checkpoint blockade (ICB)-based therapy. Association of irAEs with survival was assessed using a Cox regression model that incorporated irAE occurrence as a time-dependent covariate. Tumor samples with available RNA sequencing data were stratified by presence of an irAE to identify patterns of differential gene expression. A total of 131 patients were included. Forty-two (32%) had at least one irAE of any grade and 16 (12%) had at least one grade ≥ 3 irAE. The most common irAEs were hypothyroidism (8.3%), arthralgias (5.3%), pneumonitis (4.6%), allergic reaction (3.8%), and elevated transaminases (3.8%). Median progression-free survival (PFS) and overall survival (OS) from the time of study entry were 11.4 [95% confidence interval (CI), 10.7-15.0) and 74.6 weeks (CI, 44.9-89.7), respectively. On Cox analysis adjusting for clinical covariates that were significant in the univariate setting, the HR for an irAE (HR, 0.662; CI, 0.421-1.041) approached, but did not reach statistical significance for PFS (P = 0.074). Patients had a significantly lower HR for OS (HR, 0.443; CI, 0.246-0.798; P = 0.007) compared with those without or before an irAE. Gene expression profiling on baseline tumor samples found that patients who had an irAE had higher numbers of tumor-infiltrating dendritic cells, CD8+ T cells, and regulatory T cells as well as upregulation of immune and inflammatory pathways. SIGNIFICANCE: irAE after ICB therapy was associated with an improved OS; it also approached statistical significance for improved PFS. Patients who had an irAE were more likely to have an inflamed tumor microenvironment at baseline.

Stereotactic body radiation therapy for sarcoma pulmonary metastases.

BACKGROUND/PURPOSE: Stereotactic body radiation therapy (SBRT) is standard for patients with inoperable early-stage NSCLC. We hypothesized that SBRT for sarcoma pulmonary metastases would achieve high rates of local control with acceptable toxicity and that patients with oligometastatic disease may achieve prolonged survival following SBRT. MATERIALS/METHODS: This retrospective review included consecutive patients at our institution treated with SBRT for sarcoma pulmonary metastases. Cumulative incidence of local failure (LF) was estimated using a competing risks framework. RESULTS: We identified 66 patients treated to 95 pulmonary metastases with SBRT. The median follow-up from the time of SBRT was 36 months (95% CI 34 - 53 months). The cumulative incidence of LF at 12 and 24 months was 3.1% (95% CI 0.9 - 10.6%) and 7.4% (95% CI 4.0% - 13.9%), respectively. The 12- and 24-month overall survival was 74% (95% CI 64 - 86%) and 49% (38 - 63%), respectively. Oligometastatic disease, intrathoracic only disease, and performance status were associated with improved survival on univariable analysis. Three patients had grade 2 pneumonitis, and one patient had grade 2 esophagitis. No patients had ≥ grade 3+ toxicities. CONCLUSION: To the best of our knowledge, this is the largest series of patients treated with SBRT for pulmonary sarcoma metastases. We observed that SBRT offers an effective alternative to surgical resection with excellent local control and low proportions of toxicity.

A Phase II Study of Epacadostat and Pembrolizumab in Patients with Advanced Sarcoma.

PURPOSE: Epacadostat, an indole 2,3 dioxygenase 1 (IDO1) inhibitor, proposed to shift the tumor microenvironment toward an immune-stimulated state, showed early promise in melanoma but has not been studied in sarcoma. This study combined epacadostat with pembrolizumab, which has modest activity in select sarcoma subtypes. PATIENTS AND METHODS: This phase II study enrolled patients with advanced sarcoma into five cohorts including (i) undifferentiated pleomorphic sarcoma (UPS)/myxofibrosarcoma, (ii) liposarcoma (LPS), (iii) leiomyosarcoma (LMS), (iv) vascular sarcoma, including angiosarcoma and epithelioid hemangioendothelioma (EHE), and (v) other subtypes. Patients received epacadostat 100 mg twice daily plus pembrolizumab at 200 mg/dose every 3 weeks. The primary endpoint was best objective response rate (ORR), defined as complete response (CR) and partial response (PR), at 24 weeks by RECIST v.1.1. RESULTS: Thirty patients were enrolled [60% male; median age 54 years (range, 24-78)]. The best ORR at 24 weeks was 3.3% [PR, n = 1 (leiomyosarcoma); two-sided 95% CI, 0.1%-17.2%]. The median PFS was 7.6 weeks (two-sided 95% CI, 6.9-26.7). Treatment was well tolerated. Grade 3 treatment-related adverse events occurred in 23% (n = 7) of patients. In paired pre- and post-treatment tumor samples, no association was found between treatment and PD-L1 or IDO1 tumor expression or IDO-pathway-related gene expression by RNA sequencing. No significant changes in serum tryptophan or kynurenine levels were observed after baseline. CONCLUSIONS: Combination epacadostat and pembrolizumab was well tolerated and showed limited antitumor activity in sarcoma. Correlative analyses suggested that inadequate IDO1 inhibition was achieved.

Histology-Specific Prognostication for Radiation-Associated Soft Tissue Sarcoma.

PURPOSE: Radiation-associated sarcomas (RAS) are rare but aggressive malignancies. We sought to characterize the histology-specific presentation and behavior of soft tissue RAS to improve individualized prognostication. METHODS: A single-institutional prospectively maintained database was queried for all patients with primary, nonmetastatic RAS treated with surgical resection from 1982 to 2019. Patients presenting with the five most common RAS histologies were propensity-matched to those with sporadic tumors of the same histology. Incidence of disease-specific death (DSD) was modeled using cumulative incidence analyses. RESULTS: Among 259 patients with RAS, the five most common histologies were malignant peripheral nerve sheath tumor (MPNST; n = 19), myxofibrosarcoma (n = 20), leiomyosarcoma (n = 24), undifferentiated pleomorphic sarcoma (UPS; n = 55), and angiosarcoma (AS; n = 62). DSD varied significantly by histology (P = .002), with RAS MPNST and UPS having the highest DSD. In unadjusted analysis, RAS MPNST was associated with increased DSD compared with sporadic MPNST (75% v 38% 5-year DSD, P = .002), as was RAS UPS compared with sporadic UPS (49% v 28% 5-year DSD, P = .004). Unadjusted DSD was similar among patients with RAS AS, leiomyosarcoma, or myxofibrosarcoma and sporadic sarcoma of the same histology. After matching RAS to sporadic patients within each histology, DSD only differed between RAS and sporadic MPNST (83% v 46% 5-year DSD, P = .013). Patients with RAS AS presented in such a distinct manner to those with sporadic AS that a successful match was not possible. CONCLUSION: The aggressive presentation of RAS is histology-specific, and DSD is driven by RAS MPNST and UPS histologies. Despite the aggressive presentation, standard prognostic factors can be used to estimate risk of DSD among most RAS. In MPNST, radiation association should be considered to independently associate with markedly higher risk of DSD.

A Phase Ib/II Randomized Study of RO4929097, a Gamma-Secretase or Notch Inhibitor with or without Vismodegib, a Hedgehog Inhibitor, in Advanced Sarcoma.

PURPOSE: Because the Hedgehog and Notch pathways are often overexpressed in mesenchymal malignancies, we evaluated the efficacy of concurrent inhibition of Notch and Hedgehog signaling using the gamma-secretase inhibitor (GSI) RO4929097 and the smoothened antagonist vismodegib in unresectable or metastatic sarcoma. PATIENTS AND METHODS: In this investigator-initiated trial, phase Ib used standard 3+3 dose escalation in which patients first received vismodegib once daily for 21 days, followed by the combination of RO4929097 concurrently with vismodegib in 21-day cycles. In phase II, patients were randomized to RO4929097 alone or in combination with vismodegib. RESULTS: Nine patients were treated in phase Ib with no dose-limiting toxicities. RO4929097 at 15 mg daily in combination with 150 mg daily of vismodegib was declared the recommended phase II dose. Most adverse events were grade ≤ 2. In phase II (closed early due to discontinuation of RO4929097 evaluation), 34 patients were randomized to RO4929097 alone and 33 to RO4929097 plus vismodegib. RO4929097 did not interfere with the steady-state concentration of vismodegib, while vismodegib reduced the plasma concentration of RO492909. No patients had an objective response. Neither progression-free nor overall survival differed significantly between treatment arms. Paired tumor biopsies from a subset of patients demonstrated inhibition of cleaved Notch. CONCLUSIONS: The combination of RO4929097 plus vismodegib was generally well tolerated. Although accrual to this study was not completed, vismodegib did not meaningfully enhance the clinical efficacy of RO4929097 in an unplanned analysis. GSIs and GSIs plus vismodegib can inhibit intratumoral Notch and downstream phosphorylated Akt signaling.

Long-term Follow-up and Patterns of Response, Progression, and Hyperprogression in Patients after PD-1 Blockade in Advanced Sarcoma.

PURPOSE: Programmed cell death protein 1 (PD-1) blockade can mediate objective responses in advanced sarcomas, but their durability has not been established and it is unclear if hyperprogressive disease (HPD) occurs in sarcomas treated with PD-1 inhibitors. EXPERIMENTAL DESIGN: We pooled patients who were treated prospectively with nivolumab or pembrolizumab as monotherapy or with bempegaldesleukin, epacadostat, ipilimumab, or talimogene laherparepvec. We did a new independent assessment for HPD and analyzed clinical, pathologic, and genomic data from baseline tumor biopsies. Our primary endpoint was the incidence of HPD; secondary endpoints were clinical or genomic correlates of response or HPD. RESULTS: We treated 134 patients with advanced sarcoma from 2015 to 2019. Twenty-one patients (16%) had a complete or partial response (CR/PR), and 30% of responses were durable for over 2 years. Forty-eight (36%) patients had stable disease (SD), 45 (34%) had progressive disease without HPD (PD), and 15 (11%) had HPD. Five patients (4%) were not evaluable for HPD. The sarcoma subtypes, sites of metastasis, clinical course, and genomic alterations in patients with PD and HPD were similar, except HPD tumors were smaller at baseline. CONCLUSIONS: In patients with advanced sarcoma, PD-1 blockade can mediate durable responses. HPD occurs in sarcoma at an incidence that is similar to what has been reported in other solid tumors, but patients with HPD were clinically and biologically similar to those who had PD. Further research is required to establish whether HPD is a biologically distinct phenomenon and whether a theoretical risk of HPD should influence patient management.

Clinical, genomic, and transcriptomic correlates of response to immune checkpoint blockade-based therapy in a cohort of patients with angiosarcoma treated at a single center.

BACKGROUND: Angiosarcoma is a histologically and molecularly heterogeneous vascular neoplasm with aggressive clinical behavior. Emerging data suggests that immune checkpoint blockade (ICB) is efficacious against some angiosarcomas, particularly cutaneous angiosarcoma of the head and neck (CHN). METHODS: Patients with histologically confirmed angiosarcoma treated with ICB-based therapy at a comprehensive cancer center were retrospectively identified. Clinical characteristics and the results of targeted exome sequencing, transcriptome sequencing, and immunohistochemistry analyses were examined for correlation with clinical benefit. Durable clinical benefit was defined as a progression-free survival (PFS) of ≥16 weeks. RESULTS: For the 35 patients included in the analyses, median PFS and median overall survival (OS) from the time of first ICB-based treatment were 11.9 (95% CI 7.4 to 31.9) and 42.5 (95% CI 19.6 to 114.2) weeks, respectively. Thirteen patients (37%) had PFS ≥16 weeks. Clinical factors associated with longer PFS and longer OS in multivariate analyses were ICB plus other therapy regimens, CHN disease, and white race. Three of 10 patients with CHN angiosarcoma evaluable for tumor mutational burden (TMB) had a TMB ≥10. Five of six patients with CHN angiosarcoma evaluable for mutational signature analysis had a dominant mutational signature associated with ultraviolet (UV) light. No individual gene or genomic pathway was significantly associated with PFS or OS; neither were TMB or UV signature status. Analyses of whole transcriptomes from nine patient tumor samples found upregulation of angiogenesis, inflammatory response, and KRAS signaling pathways, among others, in patients with PFS ≥16 weeks, as well as higher levels of cytotoxic T cells, dendritic cells, and natural killer cells. Patients with PFS <16 weeks had higher numbers of cancer-associated fibroblasts. Immunohistochemistry findings for 12 patients with baseline samples available suggest that neither PD-L1 expression nor presence of tumor-infiltrating lymphocytes at baseline appears necessary for a response to ICB-based therapy. CONCLUSIONS: ICB-based therapy benefits only a subset of angiosarcoma patients. Patients with CHN angiosarcoma are more likely to have PFS ≥16 weeks, a dominant UV mutational signature, and higher TMB than angiosarcomas arising from other primary sites. However, clinical benefit was seen in other angiosarcomas also and was not restricted to tumors with a high TMB, a dominant UV signature, PD-L1 expression, or presence of tumor infiltrating lymphocytes at baseline.

Phase Ib Trial of the Combination of Imatinib and Binimetinib in Patients with Advanced Gastrointestinal Stromal Tumors.

PURPOSE: This phase Ib trial was designed to evaluate the safety and early efficacy signal of the combination of imatinib and binimetinib in patients with imatinib-resistant advanced gastrointestinal stromal tumors (GISTs). PATIENTS AND METHODS: This trial used a standard 3 + 3 design to determine the recommended phase II dose (RP2D). Additional patients were enrolled on an expansion cohort at the RP2D enriching for succinate dehydrogenase (SDH)-deficient GISTs to explore potential efficacy. RESULTS: The trial enrolled nine patients in the dose-escalation cohort and 14 in the dose-expansion cohort including six with SDH-deficient GISTs. Imatinib 400 mg daily with binimetinib 45 mg twice daily was established as the RP2D. Dose-limiting toxicity (DLT) was asymptomatic grade 4 creatinine phosphokinase (CPK) elevation. The most common non-DLT grade 3/4 toxicity was asymptomatic CPK elevation (69.6%). Other common ≥grade 2 toxicities included peripheral edema (17.4%), acneiform rash (21.7%), anemia (30.4%), hypophosphatemia (39.1%), and aspartate aminotransferase (AST) increase (17.4%). Two serious adverse events occurred (grade 2 dropped head syndrome and grade 3 central retinal vein occlusion). No unexpected toxicities were observed. Limited clinical activity was observed in KIT-mutant GIST. For SDH-deficient GISTs, one of five had confirmed RECIST1.1 partial response (PR). The median progression-free survival (mPFS) in patients with SDH-deficient GIST was 45.1 months [95% confidence interval (CI), 15.8-not estimable (NE)]; the median overall survival (mOS) was not reached (95% CI, 31.6 months-NE). One patient with a refractory metastatic SDH-deficient GIST had an exceptional pathologic response and durable clinical benefit. CONCLUSIONS: The combination of imatinib and binimetinib is safe with manageable toxicity and has encouraging activity in SDH-deficient but not imatinib-refractory KIT/PDGFRA-mutant GISTs. The observed clinical benefits provide a motivation for a larger trial of the combination strategy in SDH-deficient GISTs.

Phase II Trial of Imatinib Plus Binimetinib in Patients With Treatment-Naive Advanced Gastrointestinal Stromal Tumor.

PURPOSE: Dual targeting of the gastrointestinal stromal tumor (GIST) lineage-specific master regulators, ETV1 and KIT, by MEK and KIT inhibitors were synergistic preclinically and may enhance clinical efficacy. This trial was designed to test the efficacy and safety of imatinib plus binimetinib in first-line treatment of GIST. METHODS: In this trial (NCT01991379), treatment-naive adult patients with confirmed advanced GISTs received imatinib (400 mg once daily) plus binimetinib (30 mg twice daily), 28-day cycles. The primary end point was RECIST1.1 best objective response rate (ORR; complete response plus partial response [PR]). The study was designed to detect a 20% improvement in the ORR over imatinib alone (unacceptable rate of 45%; acceptable rate of 65%), using an exact binomial test, one-sided type I error of 0.08 and type II error of 0.1, and a planned sample size of 44 patients. Confirmed PR or complete response in > 24 patients are considered positive. Secondary end points included Choi and European Organisation for Research and Treatment of Cancer Response Rate, progression-free survival (PFS), overall survival (OS), pathologic responses, and toxicity. RESULTS: Between September 15, 2014, and November 15, 2020, 29 of 42 evaluable patients with advanced GIST had confirmed RECIST1.1 PR. The best ORR was 69.0% (two-sided 95% CI, 52.9 to 82.4). Thirty-nine of 41 (95.1%) had Choi PR approximately 8 weeks. Median PFS was 29.9 months (95% CI, 24.2 to not estimable); median OS was not reached (95% CI, 50.4 to not estimable). Five of eight patients with locally advanced disease underwent surgery after treatment and achieved significant pathologic response (≥ 90% treatment effect). There were no unexpected toxicities. Grade 3 and 4 toxicity included asymptomatic creatinine phosphokinase elevation (79.1%), hypophosphatemia (14.0%), neutrophil decrease (9.3%), maculopapular rash (7.0%), and anemia (7.0%). CONCLUSION: The study met the primary end point. The combination of imatinib and binimetinib is effective with manageable toxicity and warrants further evaluation in direct comparison with imatinib in frontline treatment of GIST.

A randomised phase II trial of a trivalent ganglioside vaccine targeting GM2, GD2 and GD3 combined with immunological adjuvant OPT-821 versus OPT-821 alone in metastatic sarcoma patients rendered disease-free by surgery.

BACKGROUND: Recurrence after resection of metastatic sarcoma is common. The gangliosides GM2, GD2 and GD3 are strongly expressed across sarcoma subtypes. We hypothesised that generation of anti-ganglioside antibodies would control micrometastases and improve outcomes in sarcoma patients who were disease-free after metastasectomy. METHODS: We conducted a randomised phase II trial of the immunological adjuvant OPT-821 with a KLH-conjugated ganglioside vaccine targeting GM2, GD2 and GD3, versus OPT-821 alone in patients with metastatic sarcoma following complete metastasectomy. Patients received 10 subcutaneous injections at Weeks 1, 2, 3, 8, 16, 28, 40, 52, 68 and 84 and were followed for evidence of recurrent disease. The primary end-point was relapse-free survival. Secondary end-points included overall survival and serologic response. RESULTS: A total of 136 patients were randomised, 68 to each arm. The mean age was 51.2, 52.2% were male, 90.4% had relapsed disease, 86.8% had high-grade tumours and 14% had ≥4 metastases resected. Histologies included leiomyosarcoma (33%), spindle cell sarcoma (14%), undifferentiated pleomorphic sarcoma (13%), osteosarcoma (10%), synovial sarcoma (9%), liposarcoma (9%) and others (12%). Most adverse events were Grade ≤2 (83.8% and 70.6% in the vaccine and adjuvant arms, respectively). The most common (≥20% of patients) were injection site reaction (89.7%), fatigue (44.1%) and pyrexia (27.9%) on the vaccine arm, and injection site reaction (69.1%) on the adjuvant only arm. The 1-year relapse-free survival rate (34.5% and 34.8% in the vaccine and OPT-821 monotherapy arm, respectively) did not differ between arms (P = 0.725). One-year overall survival rates were 93.1% and 91.5% in the vaccine and OPT-821 monotherapy arm, respectively (P = 0.578). Serologic responses at week 9 were more frequent on the vaccine arm (96.5% of patients) than in the adjuvant arm (32.8%), and the difference between groups was durable. CONCLUSIONS: A sustained serologic response to vaccination was induced with the vaccine, but no difference in recurrence-free or overall survival was observed between treatment arms. CLINICALTRIALS: gov identifier: NCT01141491.