New phase 3 results in relapsed or refractory osteosarcoma, updated data for a direct β-catenin inhibitor in desmoid tumors and clinical findings across other rare sarcoma subtypes feature among the key studies presented at ESMO 2026. This round-up examines five abstracts, covering study designs, efficacy outcomes and safety data.
The European Society for Medical Oncology (ESMO) Congress 2026 included new findings across the sarcoma treatment landscape. Studies explored novel therapeutic approaches for patients with limited treatment options, including a phase 3 evaluation of risvutatug rezetecan in relapsed or refractory osteosarcoma and early efficacy data for zolucatetide in desmoid tumors. Additional research examined targeted therapies in tenosynovial giant cell tumor and epithelioid sarcoma, alongside an investigational approach to translocation-related soft tissue sarcomas. This article features five abstracts of clinical interest, highlighting the rationale behind each study, key efficacy and safety findings, and their potential implications for future sarcoma treatment.
ARTEMIS-011: Risvutatug rezetecan versus gemcitabine and docetaxel in R/R osteosarcoma
Abstract LBA9 | NCT06935409 | Phase 3
ARTEMIS-011 compared risvutatug rezetecan (Ris-Rez), a B7-H3-directed antibody–drug conjugate (ADC), with gemcitabine plus docetaxel (GD) in 122 heavily pretreated patients with R/R osteosarcoma. Patients were randomized 2:1 to Ris-Rez 12.0 mg/kg intravenously every three weeks or GD. At a median follow-up of 7.1 months, the primary endpoint was met: median progression-free survival (PFS) by blinded independent central review (BICR) was 5.5 versus 1.4 months (HR, 0.33; 95% CI, 0.20–0.55; P<0.0001). The objective response rate (ORR) was 15% versus 2%, and the disease control rate (DCR) was 76% versus 33%. Median duration of response with Ris-Rez was 7.6 months. Overall survival (OS) data remained immature (HR, 0.51; 95% CI, 0.21–1.23). Grade ≥3 treatment-related adverse events (TRAEs) occurred in 93% versus 83% of patients.
Key clinical takeaway
Ris-Rez improved median PFS compared with GD, with a hazard ratio of 0.33. OS data remained immature, and grade ≥3 TRAEs occurred in both treatment groups.
Zolucatetide: Direct β-catenin inhibition in desmoid tumors
Abstract 3715O | NCT05919264 | Phase 1/2
Zolucatetide is an investigational direct inhibitor of the interaction between β-catenin and T-cell factor (TCF) transcription factors. The ongoing phase 1/2 study evaluated updated safety and efficacy data in patients with desmoid tumors. At the June 22, 2026, data cutoff, 76 patients had been enrolled and treated across all dose levels. Among patients who started treatment at a dose of ≥450 mg, the ORR was 72.2% (13/18) in the 32-week landmark analysis. The DCR was 100% among 46 response-evaluable patients in this dose group. Responses were observed irrespective of prior gamma-secretase inhibitor exposure or CTNNB1 or APC mutation status. Treatment-related adverse events (TRAEs) were predominantly low-grade, and no patients discontinued treatment because of TRAEs. The selected regimen comprised 450 mg weekly for four induction cycles, followed by 300 mg every two weeks for maintenance.
Key clinical takeaway
The ORR was 72.2% among 18 patients evaluable at the 32-week landmark, while the DCR was 100% among 46 response-evaluable patients receiving a starting dose of ≥450 mg. These results represent an interim analysis of an ongoing phase 1/2 study.
TANGENT: Emactuzumab in tenosynovial giant cell tumor
Abstract LBA89 | NCT05417789 | Phase 3
TANGENT evaluated emactuzumab, a monoclonal antibody targeting colony-stimulating factor 1 receptor (CSF-1R), versus placebo in patients with TGCT not amenable to surgery. The randomized phase 3 trial investigated five intravenous infusions over eight weeks. At month 6, the ORR by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 was 29.7% with emactuzumab versus 2.2% with placebo (P<0.001). By tumor volume score (TVS), the ORR was 53.8% versus 6.7% (P<0.001). Worst pain scores decreased by 2.5 versus 0.4 points, and worst stiffness scores decreased by 2.4 versus 0.3 points, respectively. Grade ≥3 adverse events occurred in 53% of patients receiving emactuzumab versus 16% receiving placebo. Increased blood creatine phosphokinase was the most common grade 3 or 4 treatment-related adverse event, occurring in 24% of patients receiving emactuzumab.
Key clinical takeaway
Emactuzumab was associated with higher ORRs by RECIST and TVS than placebo, alongside greater reductions in reported pain and stiffness scores. Grade ≥3 adverse events occurred in 53% versus 16% of patients, respectively.
HH2853: EZH1/2 inhibition in advanced epithelioid sarcoma
Abstract 3714O | NCT04390737 | Phase 2
HH2853 (epsametostat) is an investigational EZH1/2 dual inhibitor evaluated in patients with R/R advanced epithelioid sarcoma. The open-label, multicenter phase 2 study enrolled 94 patients across 15 centers in China. Patients received oral HH2853 at 400 mg twice daily in continuous 28-day cycles. By BICR assessment using RECIST version 1.1, the ORR was 40.0% (95% CI, 28.9–52.0) and the DCR was 77.3% (95% CI, 66.2–86.2). Median duration of response was 15.6 months (95% CI, 7.5–not estimable), and median PFS was 13.1 months (95% CI, 7.4–16.6). Median OS had not been reached. Grade ≥3 TRAEs included anemia (12.8%), lymphopenia (11.7%) and hypertriglyceridemia (6.4%).
Key clinical takeaway
The phase 2 study reported an ORR of 40.0%, a DCR of 77.3% and median PFS of 13.1 months. Median OS had not been reached at the data cutoff. Grade ≥3 anemia, lymphopenia and hypertriglyceridemia were reported in 12.8%, 11.7% and 6.4% of patients, respectively.
SELNET 7.2: Cirtuvivint in translocation-related soft tissue sarcomas
Abstract 3716O | NCT07032285 | Phase 2
SELNET 7.2 evaluated cirtuvivint, an investigational pan-CDC-like kinase (CLK)/dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) inhibitor, in patients with advanced translocation-related soft tissue sarcomas (TRS) who had progressed within six months of anthracycline-based treatment. The exploratory phase 2 study enrolled 29 patients across six centers in Spain. Patients received oral cirtuvivint at 80 mg daily for five consecutive days, followed by two treatment-free days, in 28-day cycles. The three-month PFS rate was 50% (95% CI, 32–68) in the overall population and 77% (95% CI, 54–100) in the solitary fibrous tumor (SFT) subgroup. Stable disease was the best response in 65.5% of patients, while 34.5% had progressive disease. Grade 3–4 treatment-related neutropenia occurred in 24.1% of patients and thrombocytopenia in 13.7%.
Key clinical takeaway
The three-month PFS rate was 50% in the overall population and 77% in the SFT subgroup. Stable disease was the best response in 65.5% of patients, while 34.5% had progressive disease. Grade 3–4 treatment-related neutropenia and thrombocytopenia occurred in 24.1% and 13.7% of patients, respectively.
This content has been developed independently by Touch Medical Media for touchONCOLOGY. It is not affiliated with the European Society for Medical Oncology (ESMO). Views expressed are the speaker’s own and do not necessarily reflect the views of Touch Medical Media. This article was created by the editorial team utilizing AI as an editorial tool (Claude.AI and ChatGPT 5.5). The content was developed and edited by human editors. No funding was received in the publication of this article.
Disclosure: Rodrigo Munhoz has no financial or non-financial conflicts of interest to declare in relation to this article.
Cite: ESMO 2026 Sarcoma & rare tumours round-up: Five studies shaping the research landscape. touchONCOLOGY. 30th October 2026.
Editor: Sophie Nickelson
