Is IO102-IO103 legal in the United Kingdom?

A subcutaneous vaccine of two peptides from IDO1 and PD-L1, given with pembrolizumab for advanced melanoma. In a 407 person phase 3, median progression free survival was 19.4 versus 11.0 months, hazard ratio 0.77 (95% CI 0.58 to 1.00), p = 0.0558 against a threshold of 0.045: the primary endpoint was missed.

Most cancer vaccines try to raise T cells against the tumour. IO102-IO103 does something different: its two peptides come from indoleamine 2,3-dioxygenase 1 (IDO1) and programmed death ligand 1 (PD-L1), proteins expressed by the immunosuppressive cells that protect a tumour, so the T cells it raises attack the tumour's defences rather than the tumour itself.

Mechanism: In people, vaccination with IO102 and IO103 raises circulating T cells that recognise IDO1 and PD-L1 derived peptides; this has been measured by ELISpot in the phase 1/2 and window of opportunity studies, and the 2025 Nature Communications paper reports serum increases in CCL3, CCL4 and TNF-alpha in responders that were not seen in a matched anti-PD-1 monotherapy cohort. The proposed downstream effect, killing or reprogramming of IDO1 and PD-L1 expressing myeloid cells and tumour cells in the tumour microenvironment, is supported by functional assays on patient samples and by spatial transcriptomics of resected head and neck tumours showing more inflammation related gene expression in vaccinated patients.

Regulatory history: Not FDA approved. Phase 3 in first line advanced melanoma (407 participants) missed its primary endpoint, p = 0.0558 against a threshold of 0.045 (Annals of Oncology, 2026).

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for IO102-IO103 at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.