ESMO Congress 2026

Within the published literature available for citation here, there is no published phase 3 efficacy result directly corresponding to risvutatug rezetecan or B7-H3 ADCs; the closest ADC-related item is merely a trial-in-progress design abstract (TIP) for a different target (CLDN18.2) and cannot serve as established efficacy evidence for this class ^[1]. In other words, the ARTEMIS-011 presentation itself constitutes the most pivotal randomized phase 3 evidence for this asset, as its phase 3 efficacy data had not been publicly disclosed before.

What was actually reported at ESMO26 Presidential Symposium III (LBA9) is precisely this phase 3 result: ARTEMIS-011 compared the anti-B7-H3 ADC risvutatug rezetecan against gemcitabine plus docetaxel in patients with relapsed/refractory osteosarcoma after ≥2 prior systemic lines (age ≥12 years, n=122, conducted in China). With a median follow-up of 7.1 months, centrally assessed median PFS was 5.5 vs 1.4 months, HR 0.33, p<0.0001, a 67% reduction in the risk of progression or death; disease control rate was 76% vs 33%. OS data remain immature, HR 0.51, with a favorable trend. On safety there is a clear toxicity trade-off: grade ≥3 treatment-related adverse events 92.5% vs 83.3%, treatment-related serious adverse events 63.8% vs 28.6% (mostly hematologic); one case of grade 2 ILD (resolved) and no treatment-related deaths.

Chinese industry news independently covered the same study, with numbers consistent with the live posts: Hansoh Pharma announced that the phase 3 ARTEMIS-011 met its PFS primary endpoint; the trial design (failure after ≥2 prior lines, comparison against gemcitabine plus docetaxel) matches the on-site description, and the news added information not given in the live posts — the drug codes HS-20093/GSK5764227 and the 95% CI for the HR of 0.20-0.55. The CFI on-site daily ranked ARTEMIS-011 second by number of posters that day (13 people), with rezetecan counted separately at 10, indirectly reflecting the attention it drew at the meeting.

As for what this advances: relapsed/refractory osteosarcoma has had few options for years, myESMO called it 'the first progress in decades' in osteosarcoma, and some discussants posed the question 'hope or hype' — the answer hinges on follow-up and toxicity. The current step forward is that a randomized phase 3 confirmed a PFS benefit for an ADC over chemotherapy in this tumor type, with a toxicity profile that is mostly hematologic and a manageable single ILD case. The limitations are equally clear: follow-up is only 7.1 months and OS data immature; both grade ≥3 events and treatment-related serious events were higher than in the chemotherapy control arm; the sample size of 122 patients and the China-only conduct mean generalizability remains to be confirmed, with longer-term survival and safety updates awaited.