Weiss, Aaron R.

PURPOSE Detection of bone marrow disease has been a major component of rhabdomyosarcoma (RMS) staging with bilateral bone marrow aspirates/biopsies (BMAB) from the iliac crests considered the diagnostic gold standard. This study's goal was to determine if 2- 18 F-labeled fluorodeoxyglucose positron emission tomography/computed tomography ([ 18 F]FDG PET/CT) or PET/magnetic resonance imaging (MRI) may replace BMAB in RMS staging. METHODS Patients were recruited in Europe and North America. Medical records, FDG PET/CT or FDG PET/MRI (PET), and BMAB reports were collected retrospectively. Images were re-reviewed by nuclear medicine physicians at the patients' home institutions if PET reports indicated increased FDG uptake at bone/bone marrow sites or if tumor cells were detected in bone marrow samples. RESULTS PET imaging and BMAB were performed before chemotherapy and tumor resection in 301 patients with FDG-avid RMS. Bone marrow metastases were detected by PET and BMAB in 54, by PET only in 24, and by BMAB only in one of 301 patients with FDG-avid primary tumors. Absence of bone marrow metastases was confirmed by PET and BMAB in 222 of 301 patients. These observations translated into 98% sensitivity and 90% specificity for PET in detecting bone marrow metastases when BMAB was considered as gold standard. FDG-avid marrow disease was patchy (1-5 foci) in one third of cases. Patients with marrow disease indicated by PET and BMAB had more FDG-avid bone marrow foci, more metastatic sites, and lower survival than those with marrow disease indicated by PET only, suggesting more advanced disease stages. CONCLUSION Bone marrow sampling may be omitted in patients without evidence of FDG-avid bone marrow disease by PET. If there are FDG-avid bone marrow lesions, further investigation by MRI and/or biopsy should be considered.

AbstractBackgroundEmbryonal sarcoma of the liver (ESL) is a rare mesenchymal tumor most common in childhood; the optimal treatment approach is uncertain. The clinical features and outcomes of patients with ESL enrolled in a Children’s Oncology Group (COG) clinical trial that evaluated a risk‐based strategy for treating soft tissue sarcomas in patients aged <30 years were evaluated.MethodsThis subset analysis included patients with ESL enrolled in COG study ARST0332. Central review of records, pathology, and imaging confirmed the diagnosis, presenting features, and surgery extent and complications. All patients received dose‐intensive ifosfamide/doxorubicin chemotherapy, with cycle timing dependent on surgery and radiotherapy. Tumor resection occurred before study entry or after four cycles of chemotherapy; radiotherapy for residual tumor was optional.ResultsThirty‐nine eligible/evaluable patients with ESL were analyzed. All tumors were >10 cm in diameter; four were metastatic. Tumor resection was performed upfront in 23 and delayed in 16. Positive surgical margins (n = 6) and intraoperative tumor rupture (n = 6) occurred only in upfront resections. Eight patients received radiotherapy. Estimated 5‐year event‐free and overall survival were 79% (95% confidence interval [CI], 65%–93%) and 95% (95% CI, 87%–100%), respectively. Positive margins increased the local recurrence risk. One of 13 patients with documented hemorrhagic ascites and/or tumor rupture developed extrahepatic intra‐abdominal tumor recurrence.ConclusionsThe treatment strategy used in ARST0332 achieved favorable outcomes for patients with ESL despite a substantial proportion having high‐risk disease features. Deferring tumor resection until after neoadjuvant chemotherapy may decrease the risk of intraoperative tumor rupture and improve the likelihood of adequate surgical margins.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. ARST1321 was a phase II study designed to compare the near complete pathologic response rate after preoperative chemoradiation with/without pazopanib in children and adults with intermediate-/high-risk chemotherapy-sensitive body wall/extremity non-Rhabdomyosarcoma Soft Tissue Sarcoma (ClinicalTrials.gov identifier: NCT02180867 ). Enrollment was stopped early following a predetermined interim analysis that found the rate of near complete pathologic response to be significantly greater with the addition of pazopanib. As a planned secondary aim of the study, the outcome data for this cohort were analyzed. Eight-five eligible patients were randomly assigned to receive (regimen A) or not receive (regimen B) pazopanib in combination with ifosfamide and doxorubicin + preoperative radiotherapy followed by primary resection at week 13 and then further chemotherapy at week 25. As of December 31, 2021, at a median survivor follow-up of 3.3 years (range, 0.1-5.8 years), the 3-year event-free survival for all patients in the intent-to-treat analysis was 52.5% (95% CI, 34.8 to 70.2) for regimen A and 50.6% (95% CI, 32 to 69.2) for regimen B ( P = .8677, log-rank test); the 3-year overall survival was 75.7% (95% CI, 59.7 to 91.7) for regimen A and 65.4% (95% CI, 48.1 to 82.7) for regimen B ( P = .1919, log-rank test). Although the rate of near complete pathologic response was significantly greater with the addition of pazopanib, outcomes were not statistically significantly different between the two regimens.

AbstractBackground and ObjectivesThe impact upon wound healing of targeted molecular therapies, when incorporated into neoadjuvant therapy of soft tissue sarcoma, is largely unknown. Here, we describe wound complications following addition of pazopanib, a tyrosine kinase inhibitor (TKI), to neoadjuvant radiotherapy (RT) +/− chemotherapy for soft tissue sarcoma.MethodsWound complications were evaluated on dose‐finding and randomized arms of ARST1321, a phase II/III study incorporating neoadjuvant RT, +/− pazopanib, +/− ifosfamide/doxorubicin (ID) for sarcoma therapy.ResultsOf 85 evaluable patients, 35 (41%) experienced postoperative wound complications. Most (57%) were grade III. Randomization to pazopanib + RT + ID carried a 50% wound complication rate (17/34, with 47% grade III), compared to 22% (5/23) with ID + RT alone. In nonchemotherapy study arms, pazopanib + RT resulted in a 59% wound complication rate versus 25% for those receiving RT alone. Grade III wound complications occurred among 26% (15/58) of all patients receiving pazopanib. Wound complications occurred a median of 35 days postoperatively. Some occurred following diagnostic biopsies and at remote surgical sites.ConclusionThe addition of pazopanib to neoadjuvant chemotherapy and RT resulted in a higher wound complication rate following therapy of soft tissue sarcoma. The rate of grade III complications remained comparable to that reported in contemporary literature.

11504 Background: Pazopanib is a multi-targeted tyrosine kinase inhibitor (TKI) with activity in advanced soft tissue sarcoma. ARST1321 was a phase II study designed to compare the near complete pathologic response rate (≥ 90% necrosis) following preoperative chemoradiation +/- pazopanib in children and adults with intermediate/high risk chemotherapy-sensitive body wall/extremity NRSTS. Enrollment was stopped early following a predetermined interim analysis that found the rate of near complete pathologic response to be significantly greater with the addition of pazopanib. As a planned secondary analysis of the study, we now report the outcome data for this cohort. Methods: ARST1321 was a jointly designed COG and NRG Oncology study open to enrollment July 2014-October 2018. Eligible adult (≥18 years) and pediatric (< 18 years) patients with newly-diagnosed unresected body wall/extremity NRSTS were enrolled into the Chemotherapy Cohort (> 5 cm, FNCLCC grade 2/3, protocol-designated chemotherapy-sensitive histology). Following a dose-finding phase, patients were randomized to receive (Regimen A) or not receive (Regimen B) pazopanib (< 18 years: 350 mg/m2/day; ≥ 18 years: 600 mg/day) in combination with ifosfamide (7.5 gm/m2/cycle) and doxorubicin (75 mg/m2/cycle) + 45 Gy preoperative RT followed by primary resection at week 13, then further chemotherapy to week 25. Results: Eighty-five eligible patients were enrolled in the Chemotherapy Cohort and randomized to receive or not receive pazopanib. Median age 22.1 years (range: 5.7-64.2 years); 30 patients < 18 years. Most common histologies were synovial sarcoma (n = 42) and undifferentiated pleomorphic sarcoma (n = 19). As of December 31, 2021, at a median survivor follow-up of 3.3 years (range: 0.1 – 5.8 years), the 3-year event-free survival (EFS) for all patients in the intent-to-treat analysis was 52.5% (95% CI: 34.8%-70.2%) for Regimen A and 50.6% (32%-69.2%) for Regimen B (p = 0.8677); 3-year overall survival (OS) was 75.7% (59.7%-91.7%) for Regimen A and 65.4% (48.1%-82.7%) for Regimen B (p = 0.1919). Conclusions: Although the rate of near complete pathologic response was significantly greater with the addition of pazopanib to preoperative chemoradiation in children and adults with intermediate/high risk body wall/extremity NRSTS, outcomes were not statistically significantly different between the two regimens. Pathologic response could be a TKI-related phenomenon and may not be a good surrogate marker of outcome in future studies. Clinical trial information: NCT02180867.

Abstract The Children's Oncology Group (COG) uses Clinical Group (CG) and modified Tumor Node Metastasis (TNM) stage to classify rhabdomyosarcoma (RMS). CG is based on surgicopathologic findings and is determined after the completion of initial surgical procedure(s) but prior to chemotherapy and/or radiation therapy. The modified TNM stage is based on clinical and radiographic findings and is assigned prior to any treatment. These systems have evolved over several decades. We review the history, evolution, and rationale behind the current CG and modified TNM classification systems used by COG for RMS. Data from the seven most recently completed and reported frontline COG trials (D9602, D9802, D9803, ARST0331, ARST0431, ARST0531, ARST08P1) were analyzed, and confirm that CG and modified TNM stage remain relevant and useful for predicting prognosis in RMS. We propose updates based on recent data and discuss factors warranting future study to further optimize these classification systems.

AbstractChildren and adolescents with rhabdomyosarcoma (RMS) comprise a heterogeneous population with variable overall survival rates ranging between approximately 6% and 100% depending on defined risk factors. Although the risk stratification of patients has been refined across five decades of collaborative group studies, molecular prognostic biomarkers beyond FOXO1 fusion status have yet to be incorporated prospectively in upfront risk‐based therapy assignments. This review describes the evolution of risk‐based therapy and the current risk stratification, defines a new risk stratification incorporating novel biomarkers, and provides the rationale for the current and upcoming Children's Oncology Group RMS studies.

ARST1321, a trial of patients with advanced soft tissue sarcoma, was the first National Clinical Trials Network study codeveloped by pediatric and adult consortia with two treatment cohorts. We report on the findings of a survey to identify barriers to enrolling adolescent and young adult patients (15–39 years) onto the nonchemotherapy arm. The survey response rate was 31% with a 70% completion rate. Common identified reasons for low accrual in order of decreasing frequency included insufficient funding, lack of study awareness or interest, competing trials, toxicity concerns, philosophical differences in the therapy backbone, and regulatory and infrastructure barriers. Clinical Trials.gov ID: NCT02180867.

e19214 Background: ARST1321(PAZNTIS): A Phase II/III Randomized Trial of Preoperative Chemoradiation or Preoperative Radiation Plus or Minus Pazopanib (NCT02180867) was the first National Clinical Trials Network (NCTN) study co-developed by pediatric (COG) and adult (NRG Oncology) consortia anticipating enrollment of adolescent and young adult (AYA) cancer patients. ARST1321 had two treatment cohorts, enrolling patients ≥ 2 years of age to either chemotherapy (C) (chemoradiation ± pazopanib) or non-chemotherapy (NC) (radiation ± pazopanib) arms. It was anticipated adults would contribute the majority of enrollments on the NC arm based on prior enrollment patterns. While the C arm accrued as anticipated (with high enrollment of adults and children), the NC arm had low enrollment leading to premature closure. We report on AYA accrual (defined as 15-39 years) to the NC arm and a survey aiming to identify barriers to enrolling AYA patients onto ARST1321. Methods: Our survey was emailed to 161 adult, surgical, and radiation oncologists at large sarcoma centers. A link was sent to an online questionnaire via SurveyMonkey Inc. and responses were reviewed on their platform. Results: 33 patients enrolled on the ARST1321 NC arm, of which 24% were AYA. 25% of AYA enrollments were from non-COG adult cooperative groups. This trial arm was closed in October 2017 after 3.25 years of accrual below anticipated rates. The survey response rate was 31% with a 70% completion rate. Almost half of respondents were medical oncologists with most seeing 50-200 new sarcoma cases/year at an academic institution and 30% in a pediatric environment (divided equally between radiation and surgical oncologists). 70% of respondents have a joint collaboration with their pediatric oncology team with 23% having a joint clinic. 70% of respondents’ sites opened ARST1321 and anticipated 1-5 patients would be eligible for the NC cohort. However, 42% of respondents’ sites had zero patients enrolled on that arm. The most common reasons for not opening the study and/or not enrolling patients on the NC arm included: lack of interest, disagreement with the therapy, lack of a site investigator, premature study closure, patient/family decision, competing trials, insufficient reimbursement, and regulatory delays. Conclusions: Our survey highlights multiple barriers to enrollment of AYA onto cross-NCTN consortia clinical trials spanning the age spectrum. The information obtained will help inform investigators aiming to effectively design, enroll, and conduct similar trial efforts for AYA in the future.