A nectin-4 ADC with a topoisomerase payload: the toxicity is haematological

Design

multicentre, single-arm phase 1 trial with Bayesian Optimal Interval dose escalation, pharmacokinetic and efficacy expansion; 39 hospitals in China

Population

395 patients with pretreated unresectable or metastatic solid tumours, ECOG 0-1, median age 59, all Chinese

Primary outcome

safety, dose-limiting toxicity, maximum tolerated dose and recommended phase 2 dose

Effect

grade 3-4 treatment-related adverse events in 212/395 (54%), neutropenia 30%; one dose-limiting toxicity at 10 mg/kg; maximum tolerated dose not reached; 2 treatment-related deaths

SHR-A2102 pairs a fully human nectin-4-directed antibody with a topoisomerase I inhibitor payload through a cleavable linker. This phase 1 trial across 39 hospitals in China treated 395 patients with pretreated unresectable or metastatic solid tumours at 2 to 10 mg/kg every three weeks — 197 with non-small-cell lung cancer, 77 with oesophageal squamous-cell carcinoma, 68 with breast cancer, 26 head and neck, 27 other. All were Chinese; median age 59; ECOG 0-1.

One dose-limiting toxicity occurred, a grade 4 thrombocytopenia at 10 mg/kg, and the maximum tolerated dose was not reached. Grade 3-4 treatment-related adverse events affected 212 of 395 (54%): neutropenia 30%, leucopenia 19%, anaemia 17%. Treatment-related serious adverse events occurred in 25%, most often pneumonia (5%), and two patients (under 1%) died of treatment-related causes — a pulmonary embolism and a pneumonia. Median follow-up was 7.2 months.

Nectin-4 is established as a target in urothelial cancer through enfortumab vedotin; extending it to lung, oesophageal and breast tumours with a different payload is the interesting move, since it swaps the MMAE toxicity profile — neuropathy, skin, hyperglycaemia — for a topoisomerase one dominated by myelosuppression. What this trial does not report is response rate, and any judgement about activity has to wait for that.

• Expect myelosuppression rather than neuropathy from a topoisomerase I payload — a different monitoring schedule from enfortumab vedotin
• Grade 3-4 events in 54% is substantial for a pretreated population; factor that into eligibility discussions if a trial opens locally
• Pneumonia was the commonest serious event and accounted for one of the two treatment-related deaths
• All 395 patients were Chinese; pharmacokinetics and tolerability in other populations are unknown
• This is dose-finding: no comparator, and response data are not in this report

Why it matters

It tests whether nectin-4 is a target beyond urothelial cancer, with a payload whose toxicities are easier to monitor than MMAE's.

Don't overread it

Single-arm phase 1 with 7.2 months of follow-up and no reported response rate — 'promising activity' in the abstract is not a measured benefit.

The statistics, in plain English

A phase 1 trial with no control arm cannot tell you whether the drug works — the primary endpoints here were safety, dose-limiting toxicity and dose selection, and those are what it answers. 'Maximum tolerated dose not reached' means toxicity did not force a ceiling within the doses tested, not that the drug is well tolerated; 54% grade 3-4 events says otherwise.

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