Citations

TPS11570 Background: Soft tissue sarcoma (STS) is a heterogenous malignancy of mesenchymal origin and includes more than 50 biologically distinct subtypes. Leiomyosarcoma (LMS), a neoplasm of smooth muscle origin, represents up to 20% of STS. The uterus is the most common site of origin in women. Advanced uterine LMS (uLMS) is initially treated with gemcitabine + docetaxel or anthracycline-based chemotherapy but overall survival remains < 24 mos. Besides recurrent alterations in RB1, TP53 and ATRX, insight into cancer biology of uLMS remains limited. Recently, whole exome and transcriptomic sequencing studies suggest uLMS harbors characteristic defects in the homologous recombination (HR) DNA repair pathway and thus features of BRCAness. HR-deficient cancers are unable to efficiently repair double-stranded DNA breaks and appear sensitive to treatment with poly ADP-ribose polymerase (PARP) inhibitors. In preclinical studies, the combination of temozolomide (T), an alkylating agent, and olaparib (O), a PARP inhibitor, was synergistic and markedly suppressed proliferation of uLMS models. A recent phase II study in small cell lung cancer defined the RP2D for T + O where the chief toxicity was myelosuppression. Methods: NCI Protocol #10250 is a single-arm, open-label, multi-center phase II clinical trial of T + O in patients with advanced uLMS. Eligible pts have ECOG PS ≤ 2, progression on ≥ 1 prior line of therapy and disease measurable by RECIST v1.1 and amenable to image-guided biopsy. Pts receive T 75 mg/m2 PO daily + O 200 mg PO BID on days 1-7 in 21-day cycles. The 1° endpoint is objective response rate (ORR). A one-stage binomial design is used to evaluate for an ORR ≤ 10% (null hypothesis) versus ≥ 35% (alternative hypothesis). The design calls for 22 patients. If 5/22 respond, the treatment is promising. This design yields 93% power and 1-sided type I error of 6%. 2° endpoints include progression free survival and safety. All pts undergo tumor biopsies pre-treatment and during cycle 2. Tissue is used for correlative analysis interrogating uLMS for features of BRCAness through (a) whole exome sequencing/RNAseq to evaluate for alterations in HR pathway component genes, (b) RAD51 foci formation by immunohistochemistry as a functional marker of HR pathway activity and (c) protein expression of Schlafen family member number 11 (SLFN11), an emerging biomarker for PARPi. Tumors are also evaluated for MGMT protein expression, a known determinant of sensitivity to T. The study opened to accrual 10/2019. Clinical trial information: NCT03880019.

11562 Background: Soft tissue sarcoma (STS) is a heterogeneous malignancy of connective tissue. Although mTOR is implicated in STS pathogenesis, clinical activity from mTORC1 inhibitors is modest. M, a potent selective mTORC1/mTORC2 inhibitor, was more effective in STS preclinical models than inhibitors of mTORC1, IGF1R and mTORC1+IGF1R, owing to more complete suppression of PI3K/AKT/mTOR and abrogation of feedback AKT activation. P, an oral multikinase inhibitor, is approved for non-adipocytic STS and often used after progression (PD) on chemotherapy. In phase 1, the RP2D of M was 30 mg weekly. A091304 was to evaluate M as a novel targeted therapy for STS. Methods: In A091304, pts were randomized 1:1 to M 30 mg weekly or P 800 mg daily. Eligibility required Eastern Cooperative Oncology Group PS ≤ 1, progression on ≥ 1 prior chemotherapy and specific STS subtypes (cohort 1: UPS; 2: LMS; 3: MPNST, SS). Crossover to M was allowed after PD on P. 1° endpoint was progression-free survival (PFS). Assuming median PFS of P was 4.6 months (mo), 98 pts yielded 80% power to detect a hazard ratio of 0.66 favoring M [1-sided test, alpha = 0.15] and including 1 planned futility analysis. 2° endpoints were response rate, clinical benefit rate (CBR) at 4 mo and safety. After 4 of the first 12 pts randomized to P experienced ≥ grade (gr) 3 toxicity, the study was amended to begin at P 400 mg, allowing titration to 800 per investigator discretion. Results: After protocol amendment, 114 pt underwent randomization (M: 56, P: 58), and 111 initiated treatment. Median PFS was 2 mo for M and 2.1 mo for P (HR = 1.47; 1-sided 85% upper confidence boundary = 1.85), with 2 partial responses in each arm. CBR was 5.4% for M and 13.8% for P. Median OS was 10.7 mo for M and 13.9 mo for P (HR = 1.41; 95% CI 0.80-2.49). 26/43 pt with PD on P crossed over to M. Median PFS after crossover was 1.8 mo (95% CI 1.5-3.5). Gr 3 drug-related adverse events (AEs) occurred in 36% on M and 41% on P; gr 4 toxicity was rare. AEs were consistent with known effects of M and P. Conclusions: P at 400 mg daily (allowing escalation to 800 mg per investigator discretion) demonstrated a shorter PFS as compared prior randomized studies with P. Despite this, M failed to demonstrate superior clinical activity as compared to P at the interim analysis. Further work will examine activity within histology-specific cohorts and evaluate available tissue samples for evidence of pharmacodynamic activity. Support: U10CA180821, U10CA180882, U10CA180888, UG1CA233324 (SWOG); https://acknowledgments.alliancefound.org . Clinical trial information: NCT02601209 .

10526 Background: Pro-angiogenic factors may represent therapeutic targets in sarcoma. Preclinical studies have demonstrated a potential additive or synergistic interaction between anti-angiogenic agents and chemotherapy. The purpose of this study was to determine the maximum tolerated dose (MTD), toxicities, pharmacokinetic (PK) and pharmacodynamics (PD) effects of PAZIT in patients with advanced sarcoma. Methods: Patients 6-30 years of age with relapsed/refractory sarcomas were eligible. In the initial dose escalation plan (A), patients received pazopanib PO (225-450 mg/m2/dose) on Days 1-21 of 21-day cycles. Pazopanib was combined with fixed doses of irinotecan (IV 50 or PO 90 mg/m2/dose) and temozolomide PO 100 mg/m2/dose on Days 1-5. Due to DLTs, an amendment was made to the dose escalation plan (B) and patients received fixed doses of pazopanib PO (225 mg/m2/dose) on Days 1-21 of 21-day cycles and reduced irinotecan doses (IV 25-37.5 or PO 45-67.5 mg/m2/dose) and temozolomide PO 100 mg/m2/dose on Days 1-5. Oral cephalosporin diarrhea prophylaxis was required. Dose escalation followed a 3+3 design. Correlative studies included PK (pazopanib, irinotecan) and PD (angiogenic factors, ctDNA) effects. Results: Sixteen patients were treated (median age 16 years, range 7-21). The dose levels in the table were evaluated. First cycle DLTs occurred at all dose levels (Table) and included diarrhea, pancreatitis, colitis, neutropenia, hypertension, deep vein thrombosis, and ALT increase. Due to excessive toxicity, an MTD could not be established. One patient with osteosarcoma had a partial response. Four patients had prolonged stable disease > 4 cycles, including 2 patients with Ewing sarcoma (5 and 6 cycles), rhabdomyosarcoma (9 cycles), and desmoplastic small round cell tumor (6 cycles). Mean±SD plasma exposures to pazopanib, irinotecan, and SN-38 in patients treated on dose level 1B (n = 4) on Day 4 were 601±83, 1.4±0.2 and 0.1±0.04 ug/mL*hr, respectively. Analyses of correlative studies are ongoing. Conclusions: Combination PAZIT therapy is not tolerable as evaluated at these doses/schedules. This study provides important toxicity data to inform future clinical trials using combination anti-angiogenic strategies in sarcoma. Clinical trial information: NCT03139331. [Table: see text]

e19407 Background: The purpose of this study was to evaluate the impact of a continuous improvement process aimed at reducing time to treatment on minimizing the number of days spent to complete pre-treatment visits and the associated costs for patients with non-metastatic breast cancer. Methods: System-wide initiatives were implemented in 2015 to minimize time to treatment initiation (TTI), by incorporating lean process strategies and enhanced coordination. Patient and treatment information was obtained through an IRB-approved registry for the years 2015 and 2018. Average number of days spent to complete visits, TTI, and associated patient costs including driving expenses, parking, food, childcare, and lost wages were calculated and compared between the years 2015 and 2018. Results: In 2015, the median TTI was 43.5 days and the average number of separate days spent to attend multidisciplinary visits prior to first treatment was 1.86. These were reduced to 29 days and 1.52 visits, respectively, in 2018 (p < 0.0001 for both). When evaluating treatment visits by surgical procedure, the average number of visits was reduced regardless of surgical procedure. The average number of visits was highest for patients undergoing mastectomy with reconstruction (2.34 in 2015, reduced to 1.65 in 2018, p < 0.0001). A single visit to complete treatment planning was associated with patient costs of $249 as compared with multiple trips costing $491 for 2 visits and up to $1,226 for 5 visits. Conclusions: In breast cancer patients, implementing a continuous improvement process to reduce time to treatment was associated with fewer visits required prior to treatment initiation, resulting in lower patient costs.

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.

e17587 Background: Radium (Ra)-223 has become the cornerstone treatment in patients with metastatic castrate-resistant prostate cancer (mCRPC) with bone metastases. Ra-223 has been shown to suppress abnormal bone formation by inducing DNA double-strand breaks in tumor cells. This can reduce skeletal-related events, as well as improve survival and quality of life. Studies have indicated mutations that regulate DNA damage response in prostate cancer as susceptible to PARP inhibitors and platinum-based therapies. This study aims to evaluate mCRPC response to Ra-223 stratified by tumor genomics. Methods: This is a retrospective study of mCRPC patients who received Ra-223 and genetic testing within the Mayo Clinic database (Arizona, Florida, and Minnesota). Patient demographics, genetic mutations, treatment responses in terms of alkaline phosphatase (ALP) and prostate-specific antigen (PSA), and survival were assessed. Primary end points were progression-free survival (PFS) and overall survival (OS) from time of first radium treatment. Results: 239 mCRPC patients treated with Ra-223 were identified. Germline and/or somatic genetic sequencing was available in 50 patients, who had a median age of 61 years at time of diagnosis and 68 years at time of Ra-223 treatment. Median Gleason score at time of diagnosis was 8.0. 100% of patients received prior androgen deprivation therapy. 72% received prior docetaxel, and 18% received prior cabazitaxel. Notable mutations included TP53 (45.2%), TMPRSS2-ERG (28.6%), PTEN (26.2%), BRCA1/2 (14.3%), ATM (9.3%), CDK12 (7.1%), and Rb (4.9%). TMPRSS2-ERG was the second most commonly found mutation, with median OS 12.7 mo versus 15.4 mo in patients without TMPRSS2-ERG mutations (p = 0.099). In patients with CDK12 mutations (2 of 28 tested positive), PFS was 10.4 mo versus 5.6 mo in patients without CDK12 mutations (p = 0.157). The assessment of ALP and PSA response to radium treatment stratified by genetic mutation did not reach statistical significance. Conclusions: Among mCRPC patients treated with Ra-223 at Mayo Clinic, TMPRSS2-ERG was the second most commonly found genetic mutation and had observed worse survival outcomes that approached statistical significance. Prospective studies and increased sample sizes are needed to determine the impact of genetic mutations in response to Ra-223.

4003 Background: Aspirin and cyclooxygenase-2 (COX-2) inhibitors have been associated with a reduced risk of colorectal polyps and cancer in observational and randomized studies. CALGB/SWOG 80702 tested the effect of celecoxib, a COX-2 inhibitor, on reducing the risk of recurrence in stage III CC. Methods: CALGB/SWOG 80702 is a 2x2 randomized controlled phase III trial of 3 v 6 months of adjuvant FOLFOX (data previously reported as part of the IDEA collaboration) with concurrent celecoxib (400 mg daily) v placebo x 3 yrs for patients (pts) with resected stage III CC. The primary endpoint of the trial is disease-free survival (DFS), defined as time from randomization to recurrence or death from any cause. The trial was designed to provide 91% power to detect a hazard ratio (HR) of 0.79 in favor of celecoxib with 2-sided alpha = 0.05 (775 events required); due to slowing accumulation of events 4 years after complete accrual, power was lowered to 85% with same HR and alpha assumptions (696 events required). The DSMB released data on February 24, 2020 at median f/u of 5.6 yrs with 689 DFS events. Results: Between June 2010 and November 2015, 2,526 pts were consented and randomized to the trial. Treatment arms were well balanced by patient and tumor prognostic features, as well as low-dose aspirin use. Baseline characteristics included 45% female, 18% non-White, 8% Hispanic, 15% T4, 26% N2. 3-yr DFS for celecoxib was 76.3% v 73.3% for placebo (HR 0.89 [95% CI 0.77-1.04]; P = 0.14). 5-yr overall survival (OS) was 83.9% for celecoxib v 81.7% for placebo (HR 0.87 [95% CI 0.72-1.05]; P = 0.14). When considering the 4 treatment arms separately, 3-yr DFS was 77.0% for 12 months FOLFOX + celecoxib, 74.9% for 12 months FOLFOX + placebo, 75.5% for 6 months FOLFOX + celecoxib, and 71.9% for 6 months FOLFOX + placebo (log rank P = 0.22; P interaction = 0.64). There were no significant differences in grade 3-4 toxicity with celecoxib v placebo. Compliance with protocol celecoxib treatment, defined as 3 yrs of therapy completion or recurrence/death while on treatment, was 58.1% pts on celecoxib and 60.2% pts on placebo. Conclusions: The addition of celecoxib to standard chemotherapy did not significantly improve DFS or OS. Clinical trial information: NCT01150045 .

3535 Background: Peripheral blood allows for a simple non-invasive method for isolating various cancer associated circulating stromal cells (CStCs) which may predict for cancer presence. Cancer Associated Macrophage-Like cells (CAMLs), a specific CStC, are phagocytic myeloid cells that derive from an immunological response to cancer and emanate from primary tumors. Using a filtration platform we screened the peripheral blood of untreated newly diagnosed cancer patients (n = 308) for CAMLs. In parallel, we screened patients with newly diagnosed non-malignant diseases, i.e. lupus, benign cysts, etc. (n = 39), and healthy control samples (n = 76). We found that CAMLs are highly prevalent (87%) in the blood of cancer patients, but uncommon in non-malignant conditions (20%) & absent in healthy individuals (0%). Methods: Anonymized peripheral blood were taken from 308 cancer patients after confirmation of invasive malignancy [stage I (n = 76), stage II (n = 73), stage III (n = 72), stage IV (n = 65) and unstaged non-metastatic (n = 22)] with pathologically confirmed lung (n = 65), pancreas (n = 53), breast (n = 52), prostate (n = 40), esophageal (n = 30), renal cell (n = 18), hepatocellular (n = 15), neuroblastoma (n = 10), melanoma (n = 8), and other (n = 17). Further, anonymized blood was taken from patients with untreated non-malignant conditions including benign breast masses (n = 19), lupus (n = 11), liver cirrhosis (n = 5), benign prostatic hyperplasia (BPH) (n = 3), and viral infection (n = 1); or from healthy control volunteers (n = 76). CAMLs were isolated from whole peripheral blood by the CellSieve™ microfiltration technique and defined as enlarged, multinuclear cells with cytokeratin and/or CD45/CD14 positive. Results: CAMLs were found in 87% of all cancer patients regardless of stage, ~5.4 CAMLs/7.5mL blood. Specifically, CAMLs were found in 80% of Stage I, 90% Stage II, 89% Stage III, and 97% Stage IV patients. No CAMLs were found in any healthy controls, but were found in 26% of benign breast masses, 18% of lupus, 0% of BPH and 0% of cirrhosis. In total, CAML sensitivity in cancer vs healthy was 87% (CI95% 82-90%), specificity = 100% (CI95% 95-100%), PPV = 100% (CI95% 100%), NPV = 67% (CI95% 58-71%). CAML sensitivity in cancer vs benign was 87% (CI95% 82-90%), specificity = 80% (CI95% 64-91%), PPV = 97% (CI95% 95-98%), NPV = 43% (CI95% 35-51%). Conclusions: CAMLs, a Circulating Stromal Cell subtype, is a sensitive blood based biomarker found in all stages of cancer that is rare in non-malignant conditions and absent in healthy individuals.

11529 Background: Maximum tumor dimension > 8 cm. and large tumor volume have been reported to be adverse prognostic factors in patients with ES but have not been prospectively evaluated in the context of a phase 3 clinical trial with interval compressed chemotherapy. Methods: COG AEWS1031 (NCT01231906) was a randomized phase 3 clinical trial comparing interval compressed chemotherapy regimens in patients with newly diagnosed localized ES of bone and soft tissue. A correlative objective of AEWS1031 was to evaluate tumor size and volume as prognostic factors. Institution-reported dimensions of the primary tumor from baseline imaging were prospectively collected. For inclusion in this analysis, patients had to have at least 1 tumor dimension reported for tumor size analyses and dimensions in 3 axes for tumor volume analyses. Maximum dimension was dichotomized as less than vs. > / = 8cm. Tumor volume was dichotomized as less than vs. > / = 200 mL. Event-free (EFS) and overall survival (OS) from enrollment were calculated using Kaplan-Meier methods and compared between groups using a two-sided log-rank test. Hazard ratios (HR) and confidence intervals (CI) were calculated using the Cox model. Results: The 5-year EFS and OS of the 629 eligible patients was 78% (95% CI: 75-81%) and 87% (95% CI: 84-90%) respectively and there was no significant difference in both EFS and OS between the randomized interval compressed chemotherapy arms of AEWS1031. 590 of 629 (94%) patients were evaluable for maximum tumor dimension and 307 (52%) had tumors > / = 8 cm. Patients with tumors > / = 8 cm were at significantly increased risk for EFS events (p = 0.016) with estimated 5-year EFS of 73.7% (95% CI: 68.1 vs.78.4%) vs. 82.9% (95% CI 77.7-87.1%) for patients with tumors < 8 cm [HR: 1.53 (1.08-2.17)]. For tumor volume, 586 of 629 patients (93%) were evaluable and 180 (31%) had tumors > / = 200 mL. Patients with tumor volume > / = 200 mL were at significantly increased risk for EFS events (p = 0.003) with estimated 5-year EFS of 70% (95% CI: 62.3-76.4%) vs. 81.6% (95% CI: 77.2-85.2%) for patients with tumors < 200 mL [HR: 1.69 (1.2-2.39)]. Conclusions: Maximum tumor dimension and tumor volume as defined are both prognostic in patients with newly diagnosed localized ES treated with interval compressed chemotherapy. Clinical trial information: NCT01231906 .