Osteosarcoma At ESMO 2026: Risvutatug Rezetecan Lifts Progression-Free Survival From 1.4 To 5.5 Months
In this article
A New Option for Relapsed Osteosarcoma? What the ARTEMIS-011 Trial Showed at ESMO 2026
In the phase 3 ARTEMIS-011 trial, presented on October 26 at ESMO 2026 in Madrid, risvutatug rezetecan (ris-rez), an antibody-drug conjugate (ADC) that recognizes the protein B7-H3, significantly prolonged progression-free survival compared with gemcitabine plus docetaxel chemotherapy in osteosarcoma that had progressed after at least two lines of treatment: median 5.5 versus 1.4 months (HR 0.33). Overall survival data are still immature, and side effects were much more frequent than with chemotherapy. The results were also covered in OncLive's congress report. You may also want to browse our osteosarcoma guide, our rare tumor news and other congress news.
- What was found: In osteosarcoma that progressed after at least two lines of treatment, ris-rez raised median progression-free survival from 1.4 to 5.5 months compared with gemcitabine + docetaxel (BICR; HR 0.33; 95% CI 0.20–0.55; p<0.0001).
- Basis: Open-label phase 3 ARTEMIS-011: 122 patients at 24 centers in China, 2:1 randomization (80 vs 42), median follow-up 7.1 months. The share of patients still free of progression at month 4 was 65% vs 33%.
- Survival: Overall survival is immature (HR 0.51; 95% CI 0.21–1.23; not significant); 10 losses of life occurred in each arm. Seventeen patients in the control arm crossed over to ris-rez after progression.
- Cost: Grade 3 or higher adverse events 93% vs 83%, serious adverse events 64% vs 29%, dose reductions 71% vs 26%. No treatment-related loss of life was reported. The drug is investigational; there is no marketing authorization or reimbursement in Türkiye.
Why does this matter?
Osteosarcoma is the most common primary bone cancer and accounts for roughly 20–40% of bone cancers. It mostly occurs in children and young adults. According to company statements, there is no clear standard of care for patients whose disease relapses or progresses after first-line chemotherapy, and the available options have limited effect.
The question behind ARTEMIS-011 was this: can an ADC that recognizes B7-H3 on tumor cells and carries a topoisomerase I inhibitor payload delay disease progression, compared with gemcitabine + docetaxel chemotherapy, in patients who have already received at least two lines of treatment? Because the trial was conducted only in China, whether the results apply to other populations needs to be examined separately.
No. The drug has been in development for several years and has reached phase 3 in different tumor types:
What is risvutatug rezetecan and how is it used in osteosarcoma?
Risvutatug rezetecan (ris-rez; HS-20093/GSK5764227) is an antibody-drug conjugate (ADC): an antibody that recognizes the B7-H3 protein on cancer cells, linked to a topoisomerase I inhibitor. In ARTEMIS-011 it was given intravenously at 12 mg/kg every 3 weeks. The manufacturer said it will use the data for a marketing application in China.
How was the trial designed? ARTEMIS-011
| Feature | Details |
|---|---|
| Design | Phase 3, multicenter, randomized (2:1), open-label (ARTEMIS-011; NCT06935409); 24 centers in China |
| Patients | Age 12 or older, pathologically confirmed osteosarcoma; progression on or intolerance to at least 2 lines of systemic therapy; measurable lesion per RECIST 1.1; ECOG 0–1. In total 122 patients; median age 22 (ris-rez) and 21 (control); 25% and 26% were adolescents; median prior lines 2.5 and 3.0. Patients who had previously received B7-H3-targeted therapy or gemcitabine + docetaxel were not enrolled |
| Ris-rez arm (n=80) | 12 mg/kg intravenously every 3 weeks until progression or another discontinuation criterion |
| Control arm (n=42) | Gemcitabine 1000 mg/m² (days 1 and 8) + docetaxel 75 mg/m² (day 8) every 3 weeks; crossover to ris-rez allowed after BICR-confirmed progression |
| Primary endpoint | Progression-free survival (PFS) by BICR |
| Secondary endpoints | Overall survival, investigator-assessed PFS, objective response rate, disease control rate, duration of response and safety |
| Data cutoff and follow-up | June 17, 2026; median follow-up 7.1 months |
| Presentation | Xie L et al. ESMO 2026, LBA9 (October 26, 2026, Madrid) |
Figure 1 · ARTEMIS-011 trial design
122 patients were randomized 2:1 into two arms
Results
ARTEMIS-011: progression-free survival (PFS)
Median, in months. Colored bar ris-rez (80 patients), gray bar gemcitabine + docetaxel (42 patients).
BICR: HR 0.33 (95% CI 0.20–0.55; p<0.0001); investigator assessment: HR 0.30 (95% CI 0.19–0.50). Median follow-up 7.1 months. A higher value is better.
By blinded independent central review (BICR), median PFS was 5.5 months (95% CI 4.1–7.4) in the ris-rez arm and 1.4 months (95% CI 0.8–2.7) in the control arm; the risk of progression or loss of life fell by 67% (HR 0.33; 95% CI 0.20–0.55; p<0.0001). The absolute difference in medians is 4.1 months. The share of patients free of progression at month 4 was 65% vs 33%; in other words, about 32 more of every 100 patients remained progression-free at month 4. The benefit was consistent across prespecified subgroups; in adolescents aged 12 to under 18 the HR was 0.26 (95% CI 0.10–0.65).
ARTEMIS-011: response rates (BICR)
Percent. Colored bar ris-rez (80 patients), gray bar chemotherapy (42 patients).
Objective response rate: OR 7.1 (95% CI 0.9–56.1; very wide confidence interval); disease control rate: OR 6.2 (95% CI 2.8–14.0). No complete responses were seen. Median duration of response in the ris-rez arm was 7.6 months; in the control arm only 1 patient had a partial response.
Progression-free rate at month 4
Percent. Each bar represents 100 patients.
Month 4 · ris-rez
Month 4 · chemotherapy
The 4-month PFS rates from the presentation (65% and 33%) are shown; the remainder was calculated by us by subtracting from 100.
Overall survival data were immature. Ten losses of life occurred in each arm (13% in the ris-rez arm, 24% in the control arm); median overall survival was not reached in either arm (HR 0.51; 95% CI 0.21–1.23). Because the confidence interval includes 1, the difference is not statistically significant. In addition, 17 patients in the control arm crossed over to ris-rez after progression, which may make the eventual survival difference look smaller than it is. In other words, the benefit proven so far lies in delaying progression, not in survival time.
Safety
ARTEMIS-011: overall safety
Percent. Red bar ris-rez (80 patients), gray bar chemotherapy (42 patients). TRAE: treatment-related adverse event. A lower rate is better.
All patients in both arms had at least one TRAE. No treatment-related loss of life was reported. Median treatment duration was 4.5 months in the ris-rez arm and about 1.5 months in the control arm, so exposure was not equal between the arms.
ARTEMIS-011: notable adverse events
Percent. Grade 3 or higher (first four) and all grades (last three). Red bar ris-rez, gray bar chemotherapy. A lower rate is better.
Prophylactic steroids were recommended before the first ris-rez infusion to reduce fever. One patient had a treatment-related grade 2 interstitial lung disease (ILD); none occurred in the control arm.
In the ris-rez arm, side effects were mainly a fall in blood cell counts (hematologic). Grade 3 or higher adverse events were 93% vs 83% and serious adverse events 64% vs 29%; in other words, about 35 more of every 100 patients had a serious adverse event. Permanent discontinuation rates stayed low (4% vs 2%); the frequent use of dose reductions (71% vs 26%) may have played a role. This picture suggests the drug should be given at experienced centers with careful dose management.
How should the results be read?
Strengths
- A randomized, controlled phase 3 trial in a heavily pretreated group with limited options.
- The primary endpoint was measured by blinded independent central review and was consistent with the investigator assessment.
- An HR of 0.33 for progression-free survival and an absolute difference of 4.1 months in medians are clinically meaningful in this population.
- The benefit was consistent across subgroups, including adolescents.
Points to keep in mind
- No proven overall survival benefit: The data are immature (HR 0.51; 95% CI 0.21–1.23), and crossover from the control arm (17 patients) may blur the result.
- Small trial, short follow-up: 122 patients and a median of 7.1 months; the confidence interval for the objective response rate is very wide (OR 7.1; 95% CI 0.9–56.1).
- Open-label design: Patients and physicians knew which treatment was given, which carries a risk of bias for investigator-assessed results and adverse event reporting (BICR partly offsets this).
- Single country: The trial was conducted in China; the results need to be confirmed in other populations.
- No full text: The data come from the congress presentation; a peer-reviewed article is not yet available.
- Single comparator regimen: The control arm used only gemcitabine + docetaxel; there is no comparison with other options.
What does it mean in practice?
- Not a standard treatment: No approved osteosarcoma indication for ris-rez has been announced; the data will be used for a marketing application in China. Treatment of relapsed osteosarcoma should be planned by a team experienced in sarcoma, based on prior treatments and overall condition.
- Clinical trial option: The global phase 1b/2 EMBOLD Sarcoma-202 trial (NCT07602777) is evaluating ris-rez in previously treated sarcomas, including osteosarcoma; we have no information on participation by centers in Türkiye.
- Shared decision: A median progression-free survival difference of 4.1 months (a median, not an average) should be discussed together with the side-effect burden; a survival benefit has not yet been shown.
- Monitoring side effects: Blood counts, fever and signs of infection, infusion reactions, and shortness of breath or cough (possible ILD) should be monitored closely.
- Young patients: Because osteosarcoma mostly affects children and young adults, psychosocial support should be part of the treatment plan.
We covered other studies from the ESMO 2026 Presidential symposia in separate articles: maintenance tarlatamab + durvalumab in extensive-stage SCLC (DeLLphi-305), darolutamide in very high-risk prostate cancer (DASL-HiCaP), perioperative durvalumab + EV in bladder cancer (VOLGA), a personalized mRNA therapy in melanoma, divarasib in KRAS G12C and ivonescimab (HARMONi-GI1). For another ADC dataset, see our article on sonesitatug vedotin (CLARITY-Gastric01); our FDA approvals and lung cancer news sections are also up to date.
To our knowledge, risvutatug rezetecan is not licensed in Türkiye and is not covered by the Turkish Social Security Institution (SGK); no approval for osteosarcoma has been announced either (according to the sources we reviewed as of October 26, 2026). The manufacturer said it will first use the ARTEMIS-011 data for a marketing application in China; in the US the drug holds FDA Breakthrough Therapy designation. In Türkiye, access may for now be possible only through a clinical trial or special permission procedures; you would need to discuss this with your treating oncologist. We covered how new drugs reach Türkiye in our Türkiye access map.
Practical tips for patients and families
- If osteosarcoma relapses, ask for your treatment plan to be discussed, if possible, at a center experienced in sarcoma by a multidisciplinary board (medical oncology, orthopedic oncology, radiology, pathology); experience matters in rare tumors.
- Ask about clinical trial options for new drugs, and review the approved treatment regimens.
- Ask for the effect of the proposed treatment on delaying progression (in months) and on survival, together with the side effects, in numbers.
- Contact your team right away if you have fever, chills, bleeding, bruising, shortness of breath, cough or severe fatigue; low blood counts can raise the risk of infection.
- Do not hesitate to get a second opinion; our second opinion news may guide you.
- Plan palliative care and psycho-oncology services alongside treatment for symptom control and support.
- During treatment, ask your team for advice on exercise and nutrition; take a look at our patient guides.
Frequently asked questions
- What did the ARTEMIS-011 trial show?
- In the phase 3 ARTEMIS-011 trial, in osteosarcoma that had progressed after at least two lines of treatment, risvutatug rezetecan raised median progression-free survival from 1.4 to 5.5 months compared with gemcitabine + docetaxel (HR 0.33). Overall survival data are still immature.
- Is risvutatug rezetecan approved for osteosarcoma?
- No. As of October 26, 2026, no approval has been announced. The manufacturer Hansoh said it will use the data for a marketing application in China; the drug has FDA Breakthrough Therapy designation in the US, and the global phase 1b/2 EMBOLD Sarcoma-202 trial is ongoing.
- What are the most common side effects?
- Falls in blood cell counts (white blood cells, neutrophils, platelets, anemia), fever, vomiting and infusion reactions stood out. Grade 3 or higher adverse events were 93% vs 83%; no treatment-related loss of life was reported, and one patient had grade 2 ILD.
- Can this treatment be used in Türkiye?
- No. There is no marketing authorization or SGK reimbursement in Türkiye; access may for now be possible only through a clinical trial or special permission procedures. Ask your oncologist about your own situation.
Glossary
- Antibody-drug conjugate (ADC)
- A treatment in which an antibody is linked, through a connecting structure, to a chemotherapy-like drug payload. The antibody recognizes a specific protein on the tumor cell; the payload is released inside the cell.
- B7-H3
- A protein found on the surface of many tumor cells and less often in healthy tissues; it is used as a target for ADCs.
- Topoisomerase I inhibitor
- A type of drug that blocks an enzyme needed when DNA is copied (topoisomerase I), stopping the cell from dividing and ultimately triggering its self-destruction (apoptosis).
- Progression-free survival (PFS)
- The time from the start of treatment until the disease progresses or loss of life occurs.
- BICR
- Blinded independent central review: imaging results assessed by independent experts who do not know which treatment the patient received.
- Objective response / disease control rate
- The share of patients whose tumor shrinks markedly (objective response) and the share whose tumor shrinks or stays stable without growing (disease control).
- TRAE
- Adverse events that the investigators judged to be related to the treatment.
DROZDOGAN Academy Commentary
ARTEMIS-011 gives a randomized, controlled answer, with an ADC that recognizes B7-H3, to a question that has long been open in relapsed osteosarcoma: it appears possible to delay disease progression.
⚡ Why it matters
In this patient group, median progression-free survival with chemotherapy stays at about 1.5 months; its rise to 5.5 months with ris-rez is clinically notable. ADCs that recognize B7-H3 have now begun to produce positive phase 3 data in different tumors (SCLC and osteosarcoma).
✅ Strengths
A randomized phase 3 design, blinded independent central review, a consistent investigator assessment and a similar benefit in subgroups that include adolescents.
⚠️ Limitations
No overall survival benefit has been shown yet; the trial was small, open-label and conducted in a single country, with short follow-up. The side-effect burden is considerable: grade 3 or higher 93%, serious 64%, dose reduction 71%.
🩺 In practice
At this stage the drug is not an approved option; clinical trials and access programs should be considered for suitable patients. Patients should be monitored at experienced centers for low blood counts and infusion reactions.
❓ Open questions
Will an overall survival benefit emerge? Will results be similar in other populations? Would it work at first relapse or in combination with chemotherapy? Can dose optimization reduce the side-effect burden?
Bottom line: Ris-rez is a notable ADC that markedly prolongs progression-free survival in heavily pretreated relapsed osteosarcoma. It should not be regarded as standard treatment until a survival benefit is proven and the side-effect burden is well managed.
- This article was prepared in October 2026.
- It is based on OncLive and Targeted Oncology congress reports on the ESMO 2026 LBA9 presentation (Xie L et al., October 26, 2026), on statements from Hansoh Pharma/GSK and on the ClinicalTrials.gov record; we did not have access to the full presentation slides or a peer-reviewed article.
- There are small differences between sources: the registry lists an estimated enrollment of 117 and the presentation 122; this article uses the presentation figure. One July 2026 news report gave the dose as mg/m²; the registry and presentation reports give 12 mg/kg.
- Calculations made by us: the month-4 PFS difference (65 − 33 = 32 points), the serious adverse event difference (about 35 points) and the complementary rates in the stacked bar (35% and 67%). In the cards the objective response rate is rounded (2%); the exact value is 2.4%.
- Information on licensing and reimbursement in Türkiye reflects the general situation; the current status should be confirmed with TİTCK and SGK.
- Comparisons in the charts are between arms of the same trial. The diagram is derived from the text and contains no new data. The Academy commentary is our own.
References
- Xie L, Yao W, Hua Y, et al. Risvutatug rezetecan versus gemcitabine and docetaxel in heavily pretreated patients with relapsed or refractory osteosarcoma: primary results from the phase 3 ARTEMIS-011 study. ESMO Congress 2026, October 26, 2026, Madrid. Abstract LBA9.
- Ris-Rez improves PFS in relapsed/refractory osteosarcoma. OncLive, October 26, 2026. onclive.com
- ADCs shine, mixed bag for immunotherapy at ESMO 2026 Presidential Symposium III. Targeted Oncology, October 26, 2026. targetedonc.com
- ClinicalTrials.gov. ARTEMIS-011 (NCT06935409). clinicaltrials.gov
- GSK's licensor Hansoh Pharma announces positive results from a second phase III trial for Ris-Rez in China. GSK, July 28, 2026. gsk.com
- Hansoh Pharmaceutical Group. Voluntary announcement: the phase III clinical study of HS-20093 in the treatment of osteosarcoma has met the primary endpoint. HKEXnews, July 28, 2026. hkexnews.hk
- Ris-Rez extends median OS to 18.5 months vs topotecan in relapsed SCLC. OncLive, September 2026. onclive.com
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