Factors Influencing the Outcome of Patients with Primary Ewing Sarcoma of the Sacrum

Background

Ewing sarcoma (EwS) is a rare and highly malignant bone tumor primarily affecting children, adolescents, and young adults. The pelvis, trunk, and lower extremities are the most common sites, while EwS of the sacrum as a primary site is very rare, and only few studies focusing on this location are published. Due to the anatomical condition, local treatment is challenging in sacral malignancies. We analyzed factors that might influence the outcome of patients suffering from sacral EwS.

Methods

We retrospectively analyzed data of the GPOH EURO-E.W.I.N.G 99 trial and the EWING 2008 trial, with a cohort of 124 patients with localized or metastatic sacral EwS. The study endpoints were overall survival (OS) and event-free survival (EFS). OS and EFS were calculated using the Kaplan-Meier method, and univariate comparisons were estimated using the log-rank test. Hazard ratios (HRs) with respective 95% confidence intervals (CIs) were estimated in a multivariable Cox regression model.

Results

The presence of metastases (3y-EFS: 0.33 vs. 0.68; P < 0.001; HR = 3.4, 95% CI 1.7 to 6.6; 3y-OS: 0.48 vs. 0.85; P < 0.001; HR = 4.23, 95% CI 1.8 to 9.7), large tumor volume (≥200 ml) (3y-EFS: 0.36 vs. 0.69; P=0.02; HR = 2.1, 95% CI 1.1 to 4.0; 3y-OS: 0.42 vs. 0.73; P=0.04; HR = 2.1, 95% CI 1.03 to 4.5), and age ≥18 years (3y-EFS: 0.41 vs. 0.60; P=0.02; HR = 2.6, 95% CI 1.3 to 5.2; 3y-OS: 0.294 vs. 0.59; P=0.01; HR = 2.92, 95% CI 1.29 to 6.6) were revealed as adverse prognostic factors.

Conclusion

Young age seems to positively influence patients` survival, especially in patients with primary metastatic disease. In this context, our results support other studies, stating that older age has a negative impact on survival. Tumor volume, metastases, and the type of local therapy modality have an impact on the outcome of sacral EwS. Level of evidence: Level 2. This trial is registered with NCT00020566 and NCT00987636.

Association between local treatment modalities and event-free survival, overall survival, and local recurrence in patients with localised Ewing Sarcoma. Report from the Ewing 2008 trial

BACKGROUND

Local treatment is a crucial element in the standard of care for Ewing sarcoma (EWS). While systemic treatment is improved in randomised clinical trials, local treatment modalities are discussed controversially. We analysed the association between local therapy and event-free survival (EFS), overall survival (OS), and local recurrence (LR) in prospectively collected data of patients with localised EWS.

PATIENTS AND METHODS

We analysed data from the international Ewing 2008 study registered between 2009 and 2019 in 117 centres. After induction chemotherapy, patients received surgery, radiotherapy, or a combination thereof. We performed Cox regression, conducted propensity score-weighted sensitivity analysis, and performed subgroup analyses. Hazard ratios (HRs) and 95% confidence intervals are reported.

RESULTS

We included 863 patients with localised EWS (surgery alone: 331, combination therapy: 358, definitive radiotherapy: 174). In patients treated with combination therapy compared to surgery alone, EFS HR was 0.84 (0.57-1.24; p = 0.38), OS HR was 0.84 (0.57-1.23; p = 0.41), and LR HR was 0.58 (0.26-1.31; p = 0.19). Hazards of any event were increased in patients treated with definitive radiotherapy compared to surgery only, HR 1.53 (1.02-2.31; p = 0.04). Patients with poor responses to chemotherapy benefitted from combination therapy over definitive surgery with an EFS HR 0.49 (0.27-0.89; p = 0.02). Patients with pelvic tumours benefitted from combination therapy over surgery only regarding LR, HR 0.12 (0.02-0.72; p = 0.02).

CONCLUSION

Patients with poor responses to chemotherapy benefitted from radiotherapy added to surgery. In the whole group, radiotherapy alone as opposed to surgery alone increased the hazards of any event.

Effect of Radiotherapy Dose on Outcome in Nonmetastatic Ewing Sarcoma

Purpose

Radiation therapy (RT) is an integral part of Ewing sarcoma (EwS) therapy. The Ewing 2008 protocol recommended RT doses ranging from 45 to 54 Gy. However, some patients received other doses of RT. We analyzed the effect of different RT doses on event-free survival (EFS) and overall survival (OS) in patients with EwS.

Methods and Materials

The Ewing 2008 database included 528 RT-admitted patients with nonmetastatic EwS. Recommended multimodal therapy consisted of multiagent chemotherapy and local treatment consisting of surgery (S&RT group) and/or RT (RT group). EFS and OS were analyzed with uni- and multivariable Cox regression models including known prognostic factors such as age, sex, tumor volume, surgical margins, and histologic response.

Results

S&RT was performed in 332 patients (62.9%), and 145 patients (27.5%) received definitive RT. Standard dose ≤ 53 Gy (d1) was admitted in 57.8%, high dose of 54 to 58 Gy (d2) in 35.5%, and very high dose ≥ 59 Gy (d3) in 6.6% of patients. In the RT group, RT dose was d1 in 11.7%, d2 in 44.1%, and d3 in 44.1% of patients. Three-year EFS in the S&RT group was 76.6% for d1, 73.7% for d2, and 68.2% for d3 (P = .42) and in the RT group 52.9%, 62.5%, and 70.3% (P = .63), respectively. Multivariable Cox regression revealed age ≥ 15 years (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.63-4.38) and nonradical margins (HR, 1.76; 95% CI, 1.05-2.93) for the S&RT group (sex, P = .96; histologic response, P = .07; tumor volume, P = .50; dose, P = .10) and large tumor volume (HR, 2.20; 95% CI, 1.21-4.0) for the RT group as independent factors (dose, P = .15; age, P = .08; sex, P = .40).

Conclusions

In the combined local therapy modality group, treatment with higher RT dose had an effect on EFS, whereas higher dose of radiation when treated with definitive RT was associated with an increased OS. Indications for selection biases for dosage were found. Upcoming trials will assess the value of different RT doses in a randomized manner to control for potential selection bias.

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.

•

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.

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

Abstract CT177: SQ3370 in advanced solid tumors: Interim phase 1 results

Background: SQ3370, a novel therapy, utilizes Shasqi’s proprietary Click Activated Protodrugs Against Cancer (CAPAC) platform where mutually-reactive click chemistry groups release Doxorubicin (Dox) at the tumor site while minimizing systemic exposure. In animals, SQ3370 enhanced T-cell infiltration, survival, and showed activity in both injected and non-injected lesions. Minimal to no toxicity, including no cardiotoxicity was seen in up to 9-fold dose increases in animals. Conventional Dox can induce cardiomyopathy with incidences of 6-20% for cumulative doses of 500 mg/m2 in humans. Here we report interim results of the Phase 1 trial (SQ3370-001; NCT04106492).

Methods: SQ3370 has 2 components: 1) Intratumoral injection of a protodrug-activating biopolymer (SQL70); 2) then 5 consecutive daily IV infusions of an attenuated protodrug of Dox (SQP33). Key criteria for enrollment include locally advanced to metastatic solid tumors, ≤300 mg/m2 prior exposure to DOX, ECOG status 0 or 1, and no limit to the number of prior systemic therapies. Primary objectives include safety and determining Phase 2 dose. Dose escalation was assessed in 2 stages: 1) accelerated titration; 2) 3+3 design. Dose-limiting toxicity (DLT) was evaluated in cycle 1.

Results: As of 26NOV2021 data cut, 17 patients (pts) in 8 dose escalation cohorts have been enrolled. MTD has not been reached. Median age was 59 years (26-79), 53% were females, and were ECOG 1 (59%). Prior procedures included surgery (82%) and radiation (47%). At study entry, 82% of pts had metastases with a median number of metastatic sites being 2 (1-5). Solid tumors were sarcoma (65%), and cancers of the skin, breast, and gynecologic organs were 12% for each, respectively. Sixteen of 17 (94%) pts received prior chemotherapy with 47% receiving prior Dox. Median number of prior systemic therapies was 2 (1-7). Intratumoral injection sites include soft tissue and chest wall. Of the 17 pts, 65% received &gt;500 mg/m2, 53% (&gt;1000), and 29% (&gt;2000) cumulative Dox given as SQP33. Median duration of treatment was 3 cycles (1-10). No DLTs were observed. Most frequent AEs, regardless of causality, included nausea (n = 9), fatigue (n = 6) and anemia (n = 5). No signs of cardiomyopathy were seen in pts with an echo performed within 1 mo. of study start. Although &gt;50% of pts received &gt;1000 mg/m2, ejection fraction (LVEF) remained normal. No AEs that led to discontinuation or death were related to SQ3370. All pts were evaluable for response. At a median follow-up of 10 wks (4-30), 65% of pts had SD as best response. Median duration of SD was 80 days (37-186) with 64% sustaining SD for ≥60 days, corresponding to an overall disease control rate of 65%. The remainder of pts had PD as best response. Over 35% of pts remain on drug.

Conclusions: SQ3370 was well tolerated. No DLTs and normal LVEF were seen with pts receiving &gt;1000 mg/m2 Dox cumulative doses. Dose escalation is ongoing. Preliminary evidence of disease control was observed in this heavily pre-treated, high cancer burden, solid tumor pt population.

Citation Format: Sant P. Chawla, Kathleen Batty, Vivek Bhadri, Nam Bui, Alexander D. Guminski, Jose M. Mejia Oneto, Sangeetha Srinivasan, James F. Strauss, Vivek Subbiah, Mia C. Weiss, Rosalind Wilson, Nathan A. Yee, Michael Zacharian, Vineet Kwatra. SQ3370 in advanced solid tumors: Interim phase 1 results [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT177.

Interim phase 1 results for SQ3370 in advanced solid tumors

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Background: SQ3370, a novel therapy, utilizes Shasqi’s proprietary Click Activated Protodrugs Against Cancer (CAPAC) platform where mutually-reactive click chemistry groups release Doxorubicin (Dox) at the tumor site minimizing systemic exposure. In animals, SQ3370 enhanced survival, T-cell infiltration and antitumor responses in injected and non-injected tumors. Minimal to no toxicity, including no cardiotoxicity was seen in up to 9-fold dose increases in animals. Conventional Dox can induce cardiomyopathy at incidences of 1-20% for cumulative doses from 300-500 mg/m2 in humans and re-treatment with Dox is less effective in heavily pre-treated patients (pts). Here we report interim results of the Phase 1 ( NCT04106492 ). Methods: SQ3370 has 2 components: 1) Intratumoral injection of a protodrug-activating biopolymer (SQL70: 10 mL or 20 mL); 2) 5 consecutive daily IV infusions of an attenuated protodrug of Dox (SQP33). Key eligibility includes locally advanced or metastatic solid tumors, ≤300 mg/m2 prior exposure to Dox, ECOG 0-1 and no limit to prior systemic therapies. Primary objectives include safety and determining Phase 2 dose. Dose escalation was assessed in 2 stages: 1) accelerated titration; 2) 3+3 design. Results: As of 31JAN2022 data cut, 26 pts were treated, 21 with 10 mL biopolymer (bp) and 5 with 20 mL bp over 9 dose escalation protodrug cohorts. MTD has not been reached. Median age was 61 years (26-84), 62% were females, and 69% were ECOG 1. Prior procedures included surgery (89%) and radiation (62%). At study entry, 77% of pts had metastases with a median number of metastatic sites being 2 (1-5); most frequently lung (50%). Tumors were sarcoma (73%), breast cancer (7.7%), gyne (7.7%) and other (11.5%). Twenty-four of 26 (92%) pts received prior systemic therapies with 50% receiving prior Dox. Median number of prior systemic therapies was 2 (1-7). Of the 26 pts, 62% received > 500 mg/m2 cumulative Dox given as SQP33. Median duration of treatment was 2 cycles (1-12). Most frequent AEs, regardless of causality, for the 10 mL bp group included nausea (n = 11), fatigue (n = 9) and anemia (n = 6), and for the 20 mL bp group included anemia (n = 3) and nausea (n = 2). Ejection fraction (LVEF) remained normal during the study period. No AEs that led to discontinuation or death were related to SQ3370 by investigator. At a median follow-up of 9.2 wks (3-37), 21 pts were evaluable. SD was best response in 71%. Median duration of SD was 80-dys (37-186) corresponding to an overall disease control rate (CR+ PR+ SD x 30-dys) of 71% (68% in 10 mL bp; 100% in 20 mL bp). The remainder of pts had PD as best response. Over 38% of pts remain on drug. Conclusions: SQ3370 with 10 mL or 20 mL biopolymer was well tolerated in pts with half being re-treated with Dox. Although > 60% of pts received > 500 mg/m2 cumulative Dox given as SQP33, LVEF remained normal. Preliminary evidence of disease control was observed in pts despite heavy prior pre-treatment and high cancer burden. Dose escalation is ongoing. Clinical trial information: NCT04106492.

Value of adjuvant radiotherapy in patients with localized Ewing sarcoma at the extremities: Report from the Ewing 2008 trial

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Background: In patients with Ewing Sarcoma (EWS), adjuvant radiotherapy is often performed after surgery that could not obtain wide margins or after poor histological response to surgery. However, the benefit of adjuvant radiotherapy needs further investigation. Therefore, we compared event-free survival (EFS) between surgery (SX) alone and SX combined with radiation therapy (RT), performed a subgroup analysis and identified independent prognostic factors. Methods: The data from localized EWS patients with tumors at the extremities that were treated in the Ewing 2008 trial from 2009-2018 were included in this analysis. Patients received induction chemotherapy according to the protocol and then underwent local therapy. Patients receiving SX or adjuvant RT (combined SX/RT) were included in this analysis. Hazard ratios (HRs) (95% Confidence Intervals (CIs)) were calculated using Cox regression. Results: 360 out of 863 patients (41.7%) presented with an EWS at the extremities with 81 tumors at the upper extremity, and 279 tumors at the lower extremity. Most patients were treated with surgery only (223, 61.94%), while 125 patients (34.72%) were treated with SX plus RT. Adjuvant radiotherapy was conducted after a median time of 69 days (1st quartile, 3rd quartile; 54, 109). Median EFS at 5-years for all patients was 0.74 (0.69, 0.80), 0.76 (0.70, 0.83) for patients after surgery only, and 0.73 (0.64, 0.83) after combined RT/SX. After adjusting for sex, age, tumor volume, histological response and surgical margins, the HR for combined RT/SX vs SX alone was 0.69 (0.37, 1.26), p = 0.22. In patients with poor histological response to surgery (≥10% vital tumor cells) and with high tumor volume (≥ 200mL), additional radiotherapy did not decrease the hazards of any event, HR 0.72 (0.25, 2.06), p = 0.54. We identified high tumor volume, poor histological response to surgery as well as intralesional resection of the tumor as independent prognostic factors after adjusting for other known prognostic factors with HRs of 1.73 (1.04, 2.90), p = 0.03; 2.79 (1.69, 4.62), p < 0.0001 and 215.9 (13.17, 3538.61), p = 0.0002, respectively. Surgical complication was not a prognostic factor after adjusting for above mentioned variables, HR 0.85 (0.31, 2.34), p = 0.75. Conclusions: In our cohort, adjuvant radiotherapy was not superior compared to surgery alone in all patients with localized EWS at the extremities and neither in a subgroup of patients with high-risk factors. Poor histological response, intralesional tumor resection as well as high tumor volume were identified as independent negative prognostic factors. Clinical trial information: NCT00987636.

Metastatic osteosarcoma bowel perforation secondary to chemotherapy-induced tumour necrosis

Osteosarcoma is the most common paediatric and adolescent primary bone malignancy and is highly chemosensitive. Gastrointestinal metastases from osteosarcomas are rare. Bowel perforation secondary to chemotherapy is a potential serious complication reported in ovarian, colorectal and haematological malignancies. We report the first documented case of chemotherapy-mediated bowel perforation in an osteosarcoma patient with gastrointestinal metastases. A man in his 20s, with a history of resected osteosarcoma in remission, presented with abdominal pain. A computed tomography (CT) scan demonstrated a large calcified intrabdominal mass (15×13×9 cm) consistent with new peritoneal disease. After one cycle of palliative ifosfamide and etoposide chemotherapy, he developed a large bowel perforation and neutropenic sepsis consequently requiring resection of the perforated mass. Chemotherapy-induced bowel perforation is a rare but serious complication that should be considered in patients with osteosarcoma, and other chemosensitive malignancies, with intra-abdominal metastases. Recommencement of systemic therapies after bowel complications must be assessed cautiously on a case-by-case basis.

High-Dose Treosulfan and Melphalan as Consolidation Therapy Versus Standard Therapy for High-Risk (Metastatic) Ewing Sarcoma

PURPOSE

Ewing 2008R3 was conducted in 12 countries and evaluated the effect of treosulfan and melphalan high-dose chemotherapy (TreoMel-HDT) followed by reinfusion of autologous hematopoietic stem cells on event-free survival (EFS) and overall survival in high-risk Ewing sarcoma (EWS).

METHODS

Phase III, open-label, prospective, multicenter, randomized controlled clinical trial. Eligible patients had disseminated EWS with metastases to bone and/or other sites, excluding patients with only pulmonary metastases. Patients received six cycles of vincristine, ifosfamide, doxorubicin, and etoposide induction and eight cycles of vincristine, actinomycin D, and cyclophosphamide consolidation therapy. Patients were randomly assigned to receive additional TreoMel-HDT or no further treatment (control). The random assignment was stratified by number of bone metastases (1, 2-5, and > 5). The one-sided adaptive-inverse-normal-4-stage-design was changed after the first interim analysis via Müller-Schäfer method.

RESULTS

Between 2009 and 2018, 109 patients were randomly assigned, and 55 received TreoMel-HDT. With a median follow-up of 3.3 years, there was no significant difference in EFS between TreoMel-HDT and control in the adaptive design (hazard ratio [HR] 0.85; 95% CI, 0.55 to 1.32, intention-to-treat). Three-year EFS was 20.9% (95% CI, 11.5 to 37.9) in TreoMel-HDT and 19.2% (95% CI, 10.8 to 34.4) in control patients. The results were similar in the per-protocol collective. Males treated with TreoMel-HDT had better EFS compared with controls: median 1.0 years (95% CI, 0.8 to 2.2) versus 0.6 years (95% CI, 0.5 to 0.9); P = .035; HR 0.52 (0.28 to 0.97). Patients age < 14 years benefited from TreoMel-HDT with a 3-years EFS of 39.3% (95% CI, 20.4 to 75.8%) versus 9% (95% CI, 2.4 to 34); P = .016; HR 0.40 (0.19 to 0.87). These effects were similar in the per-protocol collective. This observation is supported by comparable results from the nonrandomized trial EE99R3.

CONCLUSION

In patients with very high-risk EWS, additional TreoMel-HDT was of no benefit for the entire cohort of patients. TreoMel-HDT may be of benefit for children age < 14 years.

Left cheek sclerosing rhabdomyosarcoma and development of isolated free flap donor site metastasis

Rhabdomyosarcoma is a rare mesenchymal malignancy with four different morphological subtypes: alveolar, embryonal, pleomorphic and spindle cell/sclerosing. It is the most common soft tissue sarcoma of children and adolescents but occurs less commonly in adults. We describe a male patient in his 20s with sclerosing rhabdomyosarcoma of the left cheek who developed an isolated free flap donor site metastasis in the first instance but subsequently progressed with bilateral pulmonary metastases. Multidisciplinary team involvement in a sarcoma specialist centre is essential and collaboration between the pathologist, radiologist, head and neck surgeon, orthopaedic surgeon, radiation oncologist and medical oncologist were integral in providing optimal management in this patient. Furthermore, this case report highlights this phenomenon of implantation metastasis in a patient with rhabdomyosarcoma, and emphasises the importance of surgical barriers between the resection and reconstruction teams in an oncological case.

Diagnosis and management of phyllodes tumours for the surgeon: An algorithm

A Phyllodes Tumour (PT) is an uncommon fibroepithelial lesion, with three histological grades - benign, borderline and malignant. PTs cause significant challenges in diagnosis, management and prognostication. Recent publications have clarified the definitions and prognostication of PTs. Contemporary data currently challenge international guidelines on PT management. We performed an in-depth literature review to develop a best-practice management algorithm for PTs. Diagnostic recommendations are that neither current imaging techniques, nor fine-needle biopsies, can reliably diagnose a PT. Core needle biopsy is the optimal diagnostic technique. Indeterminate or suspicious lesions are recommended to undergo an excisional biopsy due to the inherently heterogeneous nature of PTs. Management guidelines are that benign PTs should be completely excised, although an involved margin is acceptable in select situations. Borderline PTs should have a clear margin on excision due to their higher risk of recurrence, as well as the potential for a recurrence to progress to a malignant PT. In malignant PTs, a margin of 3 mm is acceptable as there is no reduction in recurrence risk if margins are >3 mm. Routine axillary surgery is not indicated in PTs, with axillary surgery only indicated in a histologically-confirmed positive axilla. Adjuvant treatment recommendations are that borderline and malignant PTs should be discussed at MDT, with radiotherapy considered in both. Chemotherapy should be discussed in malignant PT patients. In summary, we have developed an up-to-date simple algorithm to guide the surgeon's management of patients diagnosed with PTs and reduce excessive surgery.

367 Pharmacokinetic and immunologic data from a phase I study of the click chemistry-based therapy SQ3370 in advanced solid tumors and soft-tissue sarcoma provides proof-of-concept for the CAPAC platform

Background

Conventional chemotherapeutics lack specificity for tumor tissue and usually have anarrow therapeutic index. SQ3370, a novel therapy that activates doxorubicin (Dox) at the tumor sitewhile minimizing systemic exposure, is based on intratumoral injection of a protodrug-activatinghyaluronic acid-based biopolymer (SQL70) followed by five daily intravenous (IV) doses of an attenuatedprotodrug of Dox (SQP33). SQ3370 utilizes Shasqi’s proprietary Click Activated Protodrugs AgainstCancer (CAPAC) platform where mutually-reactive click chemistry groups in the two components allowrelease of active Dox specifically at the tumor site. In animals, SQ3370 allowed for an 8.95-fold increase in dosing with minimal systemic adverse eventsand no cardiotoxicity. SQ3370 treatment of mouse tumor models showed improved overall survival,enhanced T-cell infiltration, and a robust anti-tumor response against both biopolymer-injected andnon-injected lesions,1 suggesting that SQ3370 promotes activation of the native immune systemagainst the tumor.

Methods

SQ3370-001 (NCT04106492) is a phase 1 trial open to patients with relapsed/refractory soft-tissue sarcoma or other advanced, potentially anthracycline-responsive solid tumors with an injectablelocal or metastatic lesion and =300 mg/m 2 prior exposure to Dox (or equivalent). Primary objectivesinclude safety, tolerability, and recommended Phase 2 dose. Additional objectives include preliminaryefficacy, plasma and tumor biopsy pharmacokinetics (PK), and immune response by peripheral bloodmass cytometry/tumor IHC.

Results

To date, ten patients have been enrolled. SQ3370 treatment has been well-tolerated with nodose-limiting toxicities observed. Plasma PK appeared consistent with preclinical data; rapid conversionof SQP33 protodrug to active Dox occurred but slowed as the residence time of the injected biopolymerlengthened. Systemic exposure to active Dox peaked on days 1–2 post biopolymer injection, followed bya decline on days 3–5. Preliminary tumor analysis shows that substantial local exposure to Dox continues2 weeks after the last SQP33 dose. Immune response analysis of early patient samples suggestsincreased tumor immune cell infiltration that dynamically changes with each cycle of treatment.

Conclusions

SQ3370 appears to be well-tolerated and demonstrates proof-of-concept for the first click-chemistry-based therapy in the clinic. Preclinical and clinical PK are consistent; high tumor exposure canbe achieved, so far without the typical clinical adverse events seen with IV Dox and potentiallyimproving the therapeutic index of a frequently-used chemotherapeutic agent.

Trial Registration

NCT04106492

Reference

Srinivasan S, Yee NA, Wu K, et al. SQ3370 activates cytotoxic drug via click chemistry at tumor andelicits sustained responses in injected and non-injected lesions. Advanced Therapeutics 2021;4(3):2000243.

Abstract CT225: Phase 1 trial of SQ3370 in solid tumors

Conventional chemotherapeutic agents are effective for a broad array of patients, but have limited dosing capabilities, lack specificity, and often result in systemic toxicity. Conversely, newer cancer immunotherapies have been successful but benefit only a subset of patients and have varying response rates across different tumors. Here we present SQ3370, a novel approach that activates doxorubicin (Dox) at the tumor site while avoiding systemic toxicities commonly associated with the therapy, and may also activate an immune response against the tumor. SQ3370 is based on a local intratumoral injection of a prodrug-capturing biomaterial (SQL70) followed by 5 daily systemic infusions of an attenuated form of Dox (SQP33). Mutually-reactive click chemistry groups in the 2 components allow the release of active Dox at the tumor site.

While conventional Dox is known to induce immune activation [1] and enhance tumor responsiveness to checkpoint inhibitors [2], its benefit is limited by achievable tumor dose, cumulative cardiotoxicity, and systemic immunosuppression. We safely administered SQ3370 in dogs at 8.95-times the veterinary clinical dose of Dox with minimal side effects. In syngeneic mouse models, SQ3370 improved overall survival and induced a robust anti-tumor response against the injected lesion compared to conventional Dox. Surprisingly, SQ3370 also induced regression of the non-injected tumor and enhanced T-cell infiltration in both injected and non-injected tumors. We hypothesize that releasing Dox at a local site with SQ3370 activates the native immune system against the tumor. Thus, SQ3370 is a new therapeutic modality to treat tumors with a drug with known efficacy, Dox, and expanding its therapeutic window. SQ3370 may potentially also benefit patients with metastatic disease.

SQ3370-001 (NCT04106492), the first-in-human Phase 1 study, is currently open in the United States and Australia to treat patients with advanced solid tumors. Eligible patients are ≥18 years old with an injectable local or metastatic lesion for which published data indicates responsiveness to anthracyclines. Patients must be relapsed/refractory following standard of care therapy and must not have received &gt;225 mg/m2 of Dox (or equivalent anthracycline). The cycle length is 21 days with no limit on total cycles. Primary objectives include safety, tolerability, and recommended Phase 2 dose. Additional objectives include assessment of pharmacokinetics in plasma and tumor biopsies, preliminary efficacy per RECIST 1.1, and immune response as assessed by mass cytometry.

References

1.Mattarollo, S.R., et al. Pivotal Role of Innate and Adaptive Immunity in Anthracycline Chemotherapy of Established Tumors, Cancer Res 2011; 71(14):4809-4820.

2.Zitvogel L., et al. Mechanism of action of conventional and targeted anticancer therapies: reinstating immunosurveillance. Immunity. 2013;39:74-88.

Citation Format: Alexander Guminski, Ding Wang, Nam Bui, Vivek Bhadri, Madhawa De Silva, Robert Steffner, Nathan A. Yee, Sangeetha Srinivasan, Jose M. Mejia Oneto, M. Wayne Saville, Vivek Subbiah. Phase 1 trial of SQ3370 in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT225.

Efficacy of maintenance therapy with zoledronic acid in patients with localized Ewing sarcoma: Report from the international Ewing 2008 trial

11523

Background: Ewing 2008R1 (EudraCT2008-003658-13, Sponsor UKM) was conducted in 12 countries. It evaluated the effect of zolendronic acid (ZOL) maintenance therapy on event-free (EFS, primary endpoint) and overall survival (OS) from randomization in standard risk Ewing Sarcoma (EwS). Methods: Phase III, open label, prospective, multi-center, randomized controlled clinical trial. Eligible patients (pts) had localized EwS with either good histological response to induction chemotherapy and/or small tumors ( < 200ml). Pts received 6 cycles VIDE induction and 8 VAI (male) or 8 VAC consolidation (female) and were randomized to receive either 9 cycles of maintenance ZOL or no further treatment (control;ctrl). ZOL cycles started parallel to the 6th consolidation cycle. Randomization was stratified by tumor site (pelvis/no pelvis). Two-sided adaptive inverse-normal 4-stage design, changed after the 1st interim analysis via Müller-Schäfer method. Initial sample size 448 pts, type I error rate 5%, power 80%. Results: 284 pts were randomized between 2009 and 2018 (142 ZOL / 142 ctrl). With a median follow-up of 3.9 years, the primary endpoint EFS was not significantly different between the ZOL and ctrl group in the adaptive design (HR 0.74, 95% CI 0.43-1.28, intention to treat). 3-year (3y) EFS rates were 84.0% (95% CI 77.7-90.8%) for ZOL vs 81.7% (95% CI 75.2-88.8%) for ctrl. Results were similar in the per protocol collective. Cause-specific HR for local recurrence in ZOL was csHR 0.30 (95% CI 0.08 -1.09; p = 0.07), for metastatic progress/new metastases csHR 1.0 (CI 0.5-2.2), for combined relapse/progress csHR 0.3 (95% CI 0.1-1.7), for second malignancies csHR 4.0 (95% CI 0.45-36.1) compared to ctrl. The 3y OS was 92.8% (95% CI 88.4-97.5%) for ZOL and 94.6% (95% CI 90.9-98.6%) for ctrl. For ZOL the 5y OS was 87.3% (95% CI 80.7-94.5%) and 89% (95% CI 83.7-95.9%) for ctrl. Noticeable more renal, neurological and gut toxicities were observed for ZOL (p < 0.05), with severe renal toxicities occurring more often in the ZOL arm (p = 0.003). Conclusions: In patients with standard risk localized Ewing Sarcoma there is no benefit from maintenance treatment with zoledronic acid, but significant side effects were observed. Clinical trial information: NCT00987636 .

Mesenchymal chondrosarcoma: An Australian multi-centre cohort study

e23509

Background: Mesenchymal chondrosarcoma (MCS) is a rare sarcoma that has a more aggressive course than conventional chondrosarcoma. Treatment is often multimodal with combinations of surgery, chemotherapy and radiotherapy. This study gives opportunity to evaluate prognostic factors and treatments in an Australian setting. Methods: We performed a retrospective study on patients with MCS registered on the ACCORD prospective sarcoma database from 6 Australian sarcoma centres since 2009. We collected data including baseline demographics, clinicopathological variables, treatment characteristics and survival status. We assessed outcomes of overall survival (OS), progression-free survival (PFS) and proportions of metastatic and localised patients receiving surgery, chemotherapy and/or radiotherapy. Results: We identified 20 patients diagnosed with MCS between Jan 2001 and Dec 2019. Median age was 35 years (range 20-69 years). Two (10%) had metastatic disease at diagnosis and 7 (35%) developed metastases on follow up. Median follow-up was 20 months (0.4 – 210 months). 17 (85%) patients underwent surgical resection (17 of primary, 8 of recurrence/metastasis), 10 (50%) received chemotherapy (95% anthracycline; 1 preoperative, 9 palliative), 12 (60%) received radiotherapy (7 to primary, 9 to recurrence/metastasis), and 13 (65%) received multimodality therapy. All six patients who received surgery alone remained alive at follow-up with no metastatic disease. Table shows survival estimates for the study population. There was no difference in median OS in patients who received all therapies compared to those who did not (8.4 v 7.5 years; p = 0.53). Median PFS was not prolonged in those who received all therapies compared to those who did not (37 vs 43 months, p = 0.4). Conclusions: This study demonstrates contemporary Australian treatment patterns of MCS. Understanding treatment patterns and outcomes helps promote standardisation of treatment and design of prospective trials for novel therapeutic strategies. Future analysis of prospective patients for patient and treatment factors influencing survival is planned. [Table: see text]

Efficacy of add-on treosulfan and melphalan high-dose therapy in patients with high-risk metastatic Ewing sarcoma: Report from the International Ewing 2008R3 trial

11501

Background: Ewing 2008R3 (EudraCT2008-003658-13) was conducted in 12 countries. It evaluated the effect of treosulfan and melphalan high dose chemotherapy followed by re-infusion of autologous hematopoietic stem cells (HDTreoMel) on event-free (EFS, primary endpoint) and overall survival (OS) in high-risk Ewing Sarcoma (EwS). Methods: Phase III, open label, prospective, multi-center, randomized controlled clinical trial. Eligible patients (pts) had disseminated EwS with metastases to bone and/or other sites, excluding pts with only pleuropulmonary metastases. Pts received 6 cycles of VIDE induction and 8 cycles of VAC consolidation therapy. Patients were randomized to receive additional HDTreoMel chemotherapy or no further treatment (control), They were further stratified by number of bone metastases (1, 2-5, > 5). One-sided adaptive inverse-normal 4-stage design, changed after the 1st interim analysis via Müller-Schäfer method. Initial sample size 185 pts, type I error rate 2.5%, power 80%. Results: 109 pts were randomized between 2009 and 2018: 55 were randomized to HDTreoMel. With a median follow-up of 3.3 years, the primary endpoint EFS was not significantly different between HDTreoMel and control in the adaptive design (HR 0.85, 95% CI 0.55-1.32, intention-to-treat). 3-year (3y) EFS was 20.9 % (95% CI 11.5-37.9%) in HDTreoMel and 19.2 % (95% CI 10.8-34.4%) in control pts. Results were similar in the per protocol collective. Subgroup analyses showed that independent of treatment, male patients had a worse outcome than female patients: 3y EFS 13.3% (95% CI 5.7-31.1%) vs 25.2% (95% CI 15.5-40.8%); p = 0.07. Patients aged < 14 had a better outcome when treated in the HDTreoMel group: 3y EFS 39.3% (95% CI 20.4-75.8%) vs 9% (95% CI 2.4-34%); p = 0.016; HR 0.40 (0.19-0.87). These effects were similar in the per protocol collective. Severe toxicities of hematology, gut, general condition and infection were more pronounced in the HDTreoMel group (p < 0.05). Conclusions: In patients with very high risk EwS, additional HDTreoMel was of no benefit for the entire cohort of patients. HDTreoMel may be of benefit for children age < 14. This observation is supported by comparable results from a non-randomized trial EE99 R3 (Ladenstein et al. JCO, 2010). Clinical trial information: NCT00987636 .

High-Dose Chemotherapy Compared With Standard Chemotherapy and Lung Radiation in Ewing Sarcoma With Pulmonary Metastases: Results of the European Ewing Tumour Working Initiative of National Groups, 99 Trial and EWING 2008

PURPOSE

The R2Pulm trial was conducted to evaluate the effect of busulfan-melphalan high-dose chemotherapy with autologous stem-cell rescue (BuMel) without whole-lung irradiation (WLI) on event-free survival (main end point) and overall survival, compared with standard chemotherapy with WLI in Ewing sarcoma (ES) presenting with pulmonary and/or pleural metastases.

METHODS

From 2000 to 2015, we enrolled patients younger than 50 years of age with newly diagnosed ES and with only pulmonary or pleural metastases. Patients received chemotherapy with six courses of vincristine, ifosfamide, doxorubicin, and etoposide (VIDE) and one course of vincristine, dactinomycin, and ifosfamide (VAI) before either BuMel or seven courses of VAI and WLI (VAI plus WLI) by randomized assignment. The analysis was conducted as intention to treat. The estimates of the hazard ratio (HR), 95% CI, and P value were corrected for the three previous interim analyses by the inverse normal method.

RESULTS

Of 543 potentially eligible patients, 287 were randomly assigned to VAI plus WLI (n = 143) or BuMel (n = 144). Selected patients requiring radiotherapy to an axial primary site were excluded from randomization to avoid excess organ toxicity from interaction between radiotherapy and busulfan. Median follow-up was 8.1 years. We did not observe any significant difference in survival outcomes between treatment groups. Event-free survival was 50.6% versus 56.6% at 3 years and 43.1% versus 52.9% at 8 years, for VAI plus WLI and BuMel patients, respectively, resulting in an HR of 0.79 (95% CI, 0.56 to 1.10; P = .16). For overall survival, the HR was 1.00 (95% CI, 0.70 to 1.44; P = .99). Four patients died as a result of BuMel-related toxicity, and none died after VAI plus WLI. Significantly more patients in the BuMel arm experienced severe acute toxicities than in the VAI plus WLI arm.

CONCLUSION

In ES with pulmonary or pleural metastases, there is no clear benefit from BuMel compared with conventional VAI plus WLI.

Cediranib in patients with alveolar soft-part sarcoma (CASPS): a double-blind, placebo-controlled, randomised, phase 2 trial

Background

Alveolar soft-part sarcoma (ASPS) is a rare soft-tissue sarcoma that is unresponsive to chemotherapy. Cediranib, a tyrosine-kinase inhibitor, has shown substantial activity in ASPS in non-randomised studies. The Cediranib in Alveolar Soft Part Sarcoma (CASPS) study was designed to discriminate the effect of cediranib from the intrinsically indolent nature of ASPS.

Methods

In this double-blind, placebo-controlled, randomised, phase 2 trial, we recruited participants from 12 hospitals in the UK (n=7), Spain (n=3), and Australia (n=2). Patients were eligible if they were aged 16 years or older; metastatic ASPS that had progressed in the previous 6 months; had an ECOG performance status of 0–1; life expectancy of more than 12 weeks; and adequate bone marrow, hepatic, and renal function. Participants had to have no anti-cancer treatment within 4 weeks before trial entry, with exception of palliative radiotherapy. Participants were randomly assigned (2:1), with allocation by use of computer-generated random permuted blocks of six, to either cediranib (30 mg orally, once daily) or matching placebo tablets for 24 weeks. Treatment was supplied in number-coded bottles, masking participants and clinicians to assignment. Participants were unblinded at week 24 or sooner if they had progression defined by Response Evaluation Criteria in Solid Tumors (version 1.1); those on placebo crossed over to cediranib and all participants continued on treatment until progression or death. The primary endpoint was percentage change in sum of target marker lesion diameters between baseline and week 24 or progression if sooner, assessed in the evaluable population (all randomly assigned participants who had a scan at week 24 [or sooner if they progressed] with target marker lesions measured). Safety was assessed in all participants who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT01337401; the European Clinical Trials database, number EudraCT2010-021163-33; and the ISRCTN registry, number ISRCTN63733470 recruitment is complete and follow-up is ongoing.

Findings

Between July 15, 2011, and July 29, 2016, of 48 participants recruited, all were randomly assigned to cediranib (n=32) or placebo (n=16). 23 (48%) were female and the median age was 31 years (IQR 27–45). Median follow-up was 34·3 months (IQR 23·7–55·6) at the time of data cutoff for these analyses (April 11, 2018). Four participants in the cediranib group were not evaluable for the primary endpoint (one did not start treatment, and three did not have their scan at 24 weeks). Median percentage change in sum of target marker lesion diameters for the evaluable population was −8·3% (IQR −26·5 to 5·9) with cediranib versus 13·4% (IQR 1·1 to 21·3) with placebo (one-sided p=0·0010). The most common grade 3 adverse events on (blinded) cediranib were hypertension (six [19%] of 31) and diarrhoea (two [6%]). 15 serious adverse reactions in 12 patients were reported; 12 of these reactions occurred on open-label cediranib, and the most common symptoms were dehydration (n=2), vomiting (n=2), and proteinuria (n=2). One probable treatment-related death (intracranial haemorrhage) occurred 41 days after starting open-label cediranib in a patient who was assigned to placebo in the masked phase.

Interpretation

Given the high incidence of metastatic disease and poor long-term prognosis of ASPS, together with the lack of efficacy of conventional chemotherapy, our finding of significant clinical activity with cediranib in this disease is an important step towards the goal of long-term disease control for these young patients. Future clinical trials in ASPS are also likely to involve immune checkpoint inhibitors.

Funding

Cancer Research UK and AstraZeneca.

Activity of cediranib in alveolar soft part sarcoma (ASPS) confirmed by CASPS (cediranib in ASPS), an international, randomised phase II trial (C2130/A12118)

11004

Background: ASPS is a rare disease (0.5-1% of soft tissue sarcomas) mainly affecting young people. It is unresponsive to conventional chemotherapy. Cediranib (C), an inhibitor of vascular endothelial growth factor receptors and other receptor tyrosine kinases, has shown significant activity in ASPS in single arm phase II trials. CASPS (NCT01337401) was designed to permit discrimination between the impact of cediranib and the often intrinsically indolent nature of the disease. Methods: CASPS compared C (30mg od) with placebo (P) in a 2:1 double blind randomisation in patients (pts) age ≥16 years with metastatic ASPS progressive in the previous 6 months. Pts were unblinded at week 24, or at progression if sooner, when those on P started C. The primary endpoint of percentage change in the sum of target marker lesions (TMLsum) between baseline and week 24 (or progression if sooner) was compared between groups by Mann-Whitney test. Secondary endpoints were progression-free survival (PFS), week 24 response rate and best response (RECIST v1.1), safety/tolerability and overall survival (OS). One-sided p-values and two-sided 90% confidence intervals are reported. Results: 48 pts were recruited between 07/2011 and 07/2016 from 12 centres (UK, Australia & Spain). 52% of pts were female, median age was 31. Most common grade ≥3 adverse events on C were hypertension (23%), diarrhoea (14%) and fatigue (9%). In the evaluable population (N = 44) median change in TMLsum on C was minus 8.3% (IQR minus 26.2% to +5.9%); versus P: +13.4% (IQR minus 0.6% to +21.3%), p = 0.0013. Best response by week 24 was partial response for 6/28 (21%) C pts compared with 0/16 on P (p = 0.053) and stable disease for an additional 19/28 (68%) on C and 12/16 (75%) on P. The PFS HR (C versus P) was 0.54 (90% CI 0.30-0.97, p = 0.041), median PFS: 10.8 mths on C versus 3.7 mths on P, OS at 12 mths was C: 96%; P: 64.3%. Conclusions: CASPS, the largest randomised trial to date in this disease, confirms the activity of C in ASPS, showing a significant reduction in tumour burden and improvement in PFS. Tumour tissue and serial blood samples will subsequently be investigated to identify potential predictive and prognostic biomarkers. Clinical trial information: NCT01337401.

PD-1 blockade using pembrolizumab in adolescent and young adult patients with advanced bone and soft tissue sarcoma

3060

Background: Sarcomas represent 10–15% of cancers in adolescent and young adult (AYA) patients, and survival for those with metastatic disease or after relapse is poor. Immunotherapy with checkpoint inhibition has improved outcomes in multiple tumour types, but there are limited data on the efficacy of immunotherapy in advanced sarcomas, particularly within the AYA population. Methods: We retrospectively reviewed AYA patients with advanced bone and soft tissue sarcoma who received self-funded pembrolizumab at Chris O’Brien Lifehouse and Children’s Hospital Westmead. Initial response was evaluated after cycle three or four using RECIST v1.1 criteria. Results: Fourteen AYA patients with sarcoma received pembrolizumab 2mg/kg IV every 3 weeks from May 2015 to December 2016. Median age was 24 (14 – 35), male to female was 7:7, ECOG PS was 0 – 1 in 6 patients, 2 in 6 patients and 3 – 4 in 2 patients. Malignancy type included three patients with osteosarcoma (OS), five patients with Ewing sarcoma (ES), two patients with synovial sarcoma (SS), two patients with alveolar soft part sarcoma (ASPS), and one patient with each of embryonal rhabdomyosarcoma (RMS) and clear cell sarcoma (CCS). The median number of pembrolizumab doses was four (range 1 – 16), with one patient still receiving treatment at the time of last follow up. Treatment was generally very well tolerated with no G3-4 toxicity. One patient with ES had an excellent, sustained response; of the two patients with ASPS one had a radiological partial response with an excellent clinical response and one patient achieved stable disease. Three patients (two ES, one RMS) died of disease prior to first scheduled assessment and thus their response was not evaluable. The remaining 8 patients had progressive disease. Conclusions: Our data suggest further evaluation of the role of pembrolizumab in AYA patients with advanced sarcoma is warranted.