Purpose

Osteosarcoma is a rare cancer and a third of patients who have completed primary treatment will develop osteosarcoma recurrence. The Src pathway has been implicated in the metastatic behavior of osteosarcoma; about 95% of samples examined express Src or have evidence of downstream activation of this pathway. Saracatinib (AZD0530) is a potent and selective Src kinase inhibitor that was evaluated in adults in Phase 1 studies. The primary goal of this study was to determine if treatment with saracatinib could increase progression-free survival (PFS) for patients who have undergone complete resection of osteosarcoma lung metastases in a double-blinded, placebo-controlled trial. Patients and Methods. Subjects with recurrent osteosarcoma localized to lung and who had complete surgical removal of all lung nodules were randomized within six weeks after complete surgical resection. Saracatinib, or placebo, was administered at a dose of 175 mg orally, once daily, for up to thirteen 28-day cycles.

Results

Thirty-seven subjects were included in the analyses; 18 subjects were randomized to receive saracatinib and 19 to receive placebo. Intent-to-treat analysis demonstrated a median PFS of 19.4 months in the saracatinib treatment group and 8.6 months in the placebo treatment group (p=0.47). Median OS was not reached in either arm.

Conclusions

Although saracatinib was well tolerated in this patient population, there was no apparent impact of the drug in this double-blinded, placebo-controlled trial on OS, and Src inhibition alone may not be sufficient to suppress metastatic progression in osteosarcoma. There is a suggestion of potential clinical benefit as evidenced by longer PFS in patients randomized to saracatinib based on limited numbers of patients treated.

Lessons learned

The results from the liposarcoma cohort of SARC024 confirm previously published data and do not support the routine use of regorafenib in this patient population. Continued exploration of novel therapies, including combination approaches, is warranted for a patient population in whom limited treatment options exist.

Background

Regorafenib is a multitargeted kinase inhibitor with a kinase profile overlapping, but distinct from, pazopanib, an agent approved for recurrent and metastatic non-gastrointestinal stromal tumor (GIST), non-adipocytic soft tissue sarcoma. We conducted a randomized, phase II study of regorafenib versus placebo in refractory liposarcoma patients.

Methods

Patients with advanced or metastatic, treatment-refractory liposarcoma were randomized 1:1 to receive regorafenib 160 mg or placebo once daily (3 weeks on, 1 week off). Patients with well-differentiated liposarcoma only were excluded. Crossover for placebo was allowed upon progression. The primary endpoint was progression-free survival (PFS), according to RECIST version 1.1.

Results

Forty-eight subjects with liposarcoma (34 dedifferentiated, 12 myxoid/round cell, 2 pleomorphic) were enrolled. Median PFS was 1.87 (95% confidence interval [CI], 0.92-3.67) months for regorafenib versus 2.07 (95% CI, 1.64-3.44) months for placebo; stratified hazard ratio [HR], 0.85 (95% CI, 0.46, 1.58), p = .62. No responses were seen on regorafenib. One PR was observed on placebo. Median overall survival was 6.46 (95% CI, 4.16-23.48) months for regorafenib and 4.89 (95% CI, 3.02-9.77) months for placebo, stratified HR, 0.66 (95% CI, 0.31-1.40), p = .28). Treatment-related adverse events were similar to the known safety profile of regorafenib.

Conclusion

Regorafenib did not appear to improve PFS in treatment-refractory liposarcoma. No new significant safety signals were observed.

Background

Outcomes for children and adults with advanced soft tissue sarcoma are poor with traditional therapy. We investigated whether the addition of pazopanib to preoperative chemoradiotherapy would improve pathological near complete response rate compared with chemoradiotherapy alone.

Methods

In this joint Children's Oncology Group and NRG Oncology multicentre, randomised, open-label, phase 2 trial, we enrolled eligible adults (aged ≥18 years) and children (aged between 2 and <18 years) from 57 hospitals in the USA and Canada with unresected, newly diagnosed trunk or extremity chemotherapy-sensitive soft tissue sarcoma, which were larger than 5 cm in diameter and of intermediate or high grade. Eligible patients had Lansky (if aged ≤16 years) or Karnofsky (if aged >16 years) performance status score of at least 70. Patients received ifosfamide (2·5 g/m² per dose intravenously on days 1-3 with mesna) and doxorubicin (37·5 mg/m² per dose intravenously on days 1-2) with 45 Gy preoperative radiotherapy, followed by surgical resection at week 13. Patients were randomly assigned (1:1) using a web-based system, in an unmasked manner, to receive oral pazopanib (if patients <18 years 350 mg/m² once daily; if patients ≥18 years 600 mg once daily) or not (control group), with pazopanib not given immediately before or after surgery at week 13. The study projected 100 randomly assigned patients were needed to show an improvement in the number of participants with a 90% or higher pathological response at week 13 from 40% to 60%. Analysis was done per protocol. This study has completed accrual and is registered with ClinicalTrials.gov, NCT02180867.

Findings

Between July 7, 2014, and Oct 1, 2018, 81 eligible patients were enrolled and randomly assigned to the pazopanib group (n=42) or the control group (n=39). At the planned second interim analysis with 42 evaluable patients and a median follow-up of 0·8 years (IQR 0·3-1·6) in the pazopanib group and 1 year (0·3-1·6) in the control group, the number of patients with a 90% pathological response or higher was 14 (58%) of 24 patients in the pazopanib group and four (22%) of 18 patients in the control group, with a between-group difference in the number of 90% or higher pathological response of 36·1% (83·8% CI 16·5-55·8). On the basis of an interim analysis significance level of 0·081 (overall one-sided significance level of 0·20, power of 0·80, and O'Brien-Fleming-type cumulative error spending function), the 83·8% CI for response difference was between 16·5% and 55·8% and thus excluded 0. The improvement in pathological response rate with the addition of pazopanib crossed the predetermined boundary and enrolment was stopped. The most common grade 3-4 adverse events were leukopenia (16 [43%] of 37 patients), neutropenia (15 [41%]), and febrile neutropenia (15 [41%]) in the pazopanib group, and neutropenia (three [9%] of 35 patients) and febrile neutropenia (three [9%]) in the control group. 22 (59%) of 37 patients in the pazopanib group had a pazopanib-related serious adverse event. Paediatric and adult patients had a similar number of grade 3 and 4 toxicity. There were seven deaths (three in the pazopanib group and four in the control group), none of which were treatment related.

Interpretation

In this presumed first prospective trial of soft tissue sarcoma spanning nearly the entire age spectrum, adding pazopanib to neoadjuvant chemoradiotherapy improved the rate of pathological near complete response, suggesting that this is a highly active and feasible combination in children and adults with advanced soft tissue sarcoma. The comparison of survival outcomes requires longer follow-up.

Funding

National Institutes of Health, St Baldrick's Foundation, Seattle Children's Foundation.