Robinson, Steven I.

Abstract Chromosome region maintenance protein 1 (CRM1) mediates protein export from the nucleus and is a new target for anticancer therapeutics. Broader application of KPT-330 (selinexor), a first-in-class CRM1 inhibitor recently approved for relapsed multiple myeloma and diffuse large B-cell lymphoma, have been limited by substantial toxicity. We discovered that salicylates markedly enhance the antitumor activity of CRM1 inhibitors by extending the mechanisms of action beyond CRM1 inhibition. Using salicylates in combination enables targeting of a range of blood cancers with a much lower dose of selinexor, thereby potentially mitigating prohibitive clinical adverse effects. Choline salicylate (CS) with low-dose KPT-330 (K+CS) had potent, broad activity across high-risk hematological malignancies and solid-organ cancers ex vivo and in vivo. The K+CS combination was not toxic to nonmalignant cells as compared with malignant cells and was safe without inducing toxicity to normal organs in mice. Mechanistically, compared with KPT-330 alone, K+CS suppresses the expression of CRM1, Rad51, and thymidylate synthase proteins, leading to more efficient inhibition of CRM1-mediated nuclear export, impairment of DNA-damage repair, reduced pyrimidine synthesis, cell-cycle arrest in S-phase, and cell apoptosis. Moreover, the addition of poly (ADP-ribose) polymerase inhibitors further potentiates the K+CS antitumor effect. K+CS represents a new class of therapy for multiple types of blood cancers and will stimulate future investigations to exploit DNA-damage repair and nucleocytoplasmic transport for cancer therapy in general.

There are limited data regarding the surgical management of primary pulmonary artery sarcomas (PPAS) because of their rarity and complicated diagnostic history. The objective of this study was to analyze our institution’s long-term surgical management outcomes for PPAS in the absence of a care pathway. From May 1997 to June 2013, 8 patients (mean age 60.6 ± 11.8 years; range, 40-73 years; 5 women and 3 men) underwent surgical intervention for PPAS at our institution. The most common computed tomography finding was a luminal filling defect obstructing the pulmonary artery (PA), without evidence of extraluminal extension. Three patients underwent debulking/pulmonary endarterectomy alone and 5 patients underwent a more radical resection with PA patch angioplasty, PA resection and reconstruction, pulmonary valve replacement, and unilateral pneumonectomy. The mean postoperative survival in this series was 3.8 ± 3.6 years (range, 1-11.9 years), with 2 radical surgical resection patients alive at 4.9 and 11.9 years, respectively. For those patients with incomplete resection, 3-dimensional (3D) models were created to demonstrate the advantage of a preoperative guide for a more complete resection and what it would entail. Six patients had local recurrences with mean disease-free interval of 14 ± 10.9 months (range, 2 months-2.5 years), and 2 patients with re-resections had an overall postoperative survival of 2.8 and 11.9 years, respectively. In our small cohort of PPAS, patients treated with radical surgical resection had better survival. The small number of PPAS cases in this series makes proving this association unlikely but warrants consideration.

Although checkpoint inhibitors have been approved in multiple cancers, they are still under investigation in soft tissue sarcoma (STS). We conducted a retrospective review to report the safety, efficacy, and prognostic factors related to checkpoint inhibitors in STS. A sequential cohort of metastatic STS patients from four institutions treated with checkpoint inhibitors was assembled. Logistic and Cox regression models were applied to determine the effect of patient characteristics, prior treatment, and baseline factors on achieving the best overall response of complete response (CR), partial response (PR), or stable disease (SD) as determined by the treating physician. Eighty-eight patients with two median prior therapies received checkpoint inhibitors. Treatments included pembrolizumab in 47, nivolumab in 6, ipilimumab in 1, combination ipilimumab/nivolumab in 27, and other combination immunotherapies in 7 patients. Immunotherapy was discontinued in 54 patients—72.2% for progression, 16.7% for toxicity, and 11.1% for other reasons. Median progression-free survival (PFS) was 4.1 months and median overall survival was 19.1 months. One patient with undifferentiated pleomorphic sarcoma (UPS) achieved a CR, while 20 patients had a PR, including 7 UPS, 9 leiomyosarcoma (LMS), and 1 each with alveolar soft part sarcoma, fibroblastic sarcoma, sclerosing epithelioid fibrosarcoma, and myxofibrosarcoma. Forty-five percent (9 of 20) of LMS patients achieved a PR. Twenty-eight patients had SD. Our results confirm the activity and safety of anti-PD-1 therapy in metastatic STS. A notable response rate was observed in UPS and LMS subtypes. This study expands the knowledge base beyond what is currently available from clinical trials involving checkpoint inhibitors in metastatic STS.

e23544 Background: Rare diseases are defined as conditions that affect less than 200,000 people annually in the United States. Around 17000 cases of sarcoma will be diagnosed in 2020. Collaboration among institutions is needed to best understand rare diseases such as sarcoma. One measure of collaboration is publications with multiple institutions as authors. We sought to determine if collaboration in sarcoma has increased since 2011 and compared that to another rare disease, CNS tumors based on multi-institution-authored abstracts presented at ASCO. Methods: All sarcoma and CNS oral abstracts, clinical science symposia, poster presentations, poster discussions, and published-only ASCO Annual Meetings from 2011 to 2019 were reviewed. Collaboration was determined if the abstract authors were from more than one institution. Results: 2,134 abstracts were reviewed. Collaboration for sarcoma ranged from 0.603 to 0.720 and 0.582 to 0.755 for CNS. From 2011-2019 a positive linear trend in collaboration was found in CNS (P < 0.05), but not in sarcoma (P = NS). There was no significant trend in the incidence of collaboration in Sarcoma based on the type of presentation at ASCO. There was no difference in collaboration between bone or soft tissue sarcoma abstracts or median number of institutions collaborating between sarcoma and CNS. There were more international collaborations and absolute number of institutions in sarcoma vs CNS. Conclusions: Sarcoma collaboration has remained constant from 2011-2019 with greater number of institutions and more international collaborations as compared to CNS. CNS collaboration has increased from 2011-2019. Sarcoma collaboration at ASCO is robust and reflects the need for multi-institutional partnership.

11561 Background: Angiosarcoma has a particularly poor prognosis with 5-year overall survival rates of approximately 30-40%. Treatment of locally advanced and metastatic angiosarcoma is inadequate. Data strongly suggest concurrent, potent inhibition of VEGFR and Tie2 represents an attractive therapeutic strategy in angiosarcoma. Regorafenib displays potent VEGFR and Tie2 receptor inhibition and also possesses activity against additional potential targets in angiosarcoma including PDGFRs, RAF, KIT and FGFR, amongst others. Methods: A multicenter phase II study of regorafenib in patients with locally advanced or metastatic angiosarcoma was conducted through the Midwest Sarcoma Trials Partnership. Adequate performance status, organ function, measurable disease (RECIST 1.1) and 1-4 prior therapies were required. Regorafenib 160 mg PO daily was given in 28-day cycles (21 days on, 7 days off) until disease progression (PD) or unacceptable toxicity. The primary endpoint was progression-free survival (PFS), assessed at 16 weeks. Secondary endpoints include overall response rate (ORR), clinical benefit rate (CBR), OS, and safety and tolerability. A Simon 2-stage design was used. Results: After final enrollment of the second stage, a total of 31 pts were enrolled at 6 sites, 23 are evaluable for response. Median age was 65 (range 30-91); 50% were female, 67.7% had metastatic disease. PFS at 4 months is 52.2% with a median PFS and OS of 3.55 and 11.4 months. 1 confirmed CR and 2 PR, 12 SD and 8 PD were observed. ORR and CBR are 14.29 and 65.2%, respectively. No uncommon grade 3-4 adverse events were observed. 6 pts were non-evaluable due to refusal of further therapy and 2 patients progressed prior to first evaluation. Conclusions: Regorafenib was well tolerated in this study of pretreated patients with angiosarcomas and met its primary endpoint with a median PFS > 45% at 4 months. Treatment was feasible and did not reveal any previously unreported toxicities. Efficacy outcomes were complicated by early withdrawals of patients. RECIST responses were encouraging and regorafenib has a clinically meaningful 4-month PFS. Clinical trial information: NCT02048722 .

19561 Background: Diarrhea is a common side effect of chemotherapy (CT). At times, often unpredictably, patients develop profound diarrhea during CT. Though the clinical diagnosis of celiac disease (CD) is relatively rare, (1/ 2000), the serologic prevalence is much higher (1/ 133), suggesting a large number of undiagnosed cases. Latent CD may be unmasked by stressors, such as CT. We hypothesized that undiagnosed CD may account for some cases of severe diarrhea from CT. Methods: We performed a retrospective chart review at the Mayo Clinic (1980–2006) for patients with diagnoses of cancer and CD that received CT at our center. CD cases were confirmed by biopsy (n= 25) or serologic studies. Data analyzed included severe (grade ≥ 3,) diarrhea while on CT, site of primary cancer, diagnosis of CD prior to or after CT, and specific CT agents received. Results: We identified 27 patients with CD and cancer (12 lymphoma, 6 gastrointestinal, 2 leukemia, 2 breast, 1 brain, bladder, lung, uterine, sarcoma) who received CT at our center. Fifteen were diagnosed with CD prior to receiving CT and 12 after, with the former group presumably on a gluten-free diet. One patient was excluded for lack of clinical data. Five of remaining 14 patients (35%) managed for their CD prior to CT had diarrhea, though 4 of these 5 had only mild diarrhea (gr. 1). One patient suffered gr. 3 diarrhea, though was reported to be poorly compliant with his diet. Three patients received treatment with 5- fluorouracil (5FU), and 2 had gr. 1 diarrhea. Five of the 12 patients (42%) with celiac disease undiagnosed prior to CT were reported to have diarrhea during treatment (3 gr. 4; 2 gr. 1). Of those receiving 5FU, 3 out of 4 had severe (gr. 4) diarrhea. The small numbers of patients precluded meaningful statistical analysis. Conclusion: Patients with known CD compliant with a gluten-free diet tolerated CT well. However, in a subset of undiagnosed patients, severe diarrhea developed during CT, most notably with 5FU-based regimens. We propose that when patients have diarrhea disproportionate to other effects, CD should be considered. Also, in malignancies with a high incidence of CD such as lymphoma and small bowel cancer, underlying CD should be considered before CT is given. No significant financial relationships to disclose.

Objective. We explore the clinicopathologic features of Ewing sarcoma (ES) presenting in older adulthood. Methods. Cases of molecularly confirmed ES arising in patients aged ≥40 years were evaluated. Results. Fifty patients were identified (33 males/17 females; 41-86 years). The majority of tumors (41) arose at extraskeletal sites, while 9 were bone primaries. Twenty-eight cases showed nested architecture, while the remaining cases showed sheet-like growth. Tumor cytology was categorized as conventional (n = 39), crushed (n = 5), clear cell (n = 4), rhabdoid (n = 3), and epithelioid (n = 2). Fifty percent had necrosis, while rosettes were noted in 1 case. Immunostains performed ranged from 1 to 28 (median = 10). Follow-up (n = 43, 1-147 months) revealed 15 patients with metastasis. Conclusion. Although rare, ES should be considered in the differential diagnosis for round cell malignancies in older adult patients. In this cohort, ES is most often extraskeletal, and may show unusual morphologic features, closely simulating more common neoplasms in this age group.