Syncromune: 80% 24-month survival in Phase 1 prostate cancer trial

Syncromune has reported long-term Phase 1 data for its investigational SYNC-T Therapy SV-102 in metastatic prostate cancer, with 80% of enrolled patients alive at 24 months and median overall survival not yet reached after nearly 30 months of follow-up. The data were presented at the European Society for Medical Oncology Congress 2026 in Madrid on 23 October.

The open-label, single-arm Phase 1 study enrolled 15 patients, split between ten with metastatic castration-resistant prostate cancer (mCRPC) and five with metastatic hormone-sensitive prostate cancer (mHSPC) who had declined androgen deprivation therapy. As of the 1 April 2026 data cut, six patients had achieved a complete response; three of those six (50%) remain disease-free at follow-up durations ranging from 26.5 to 35.3 months. The previously reported objective response rate stood at 87%, with a 40% complete response rate. The mHSPC cohort of five patients recorded no deaths, while the mCRPC cohort of ten showed a median overall survival of 27.9 months.

Clinical profile and mechanism

SYNC-T Therapy SV-102 is an in situ immunotherapy that combines a cryoablation step with direct intratumoral delivery of four immune-modulating agents: abazistobart (anti-PD-1), futermestotug (anti-CTLA-4), ciltistotug (a CD40 agonist), and sitmutolimod (a TLR9 agonist). The partial freeze-thaw disrupts tumour cells, releasing patient-specific antigens, which are then exposed to the drug combination in the tumour microenvironment and draining lymph nodes. The intended effect is systemic: training immune cells to recognise and attack both treated and untreated lesions elsewhere in the body.

Principal investigator Carlos Vargas, MD, highlighted a specific observation that underpins the mechanistic rationale: "Follow-up imaging in some patients showed regression of distant metastases that were never directly treated. The potential systemic effect suggested by these observations is what makes this approach distinctive."

The safety profile across 15 patients was broadly manageable. Ninety-five per cent of treatment-emergent adverse events were grade 1 or 2, with no grade 4 or 5 events and no grade 3 or 4 immune-related toxicities reported.

Competitive context and the road ahead

The mCRPC landscape is well-populated. Approved standard-of-care agents include enzalutamide, abiraterone, cabazitaxel, and PARP inhibitors for patients with homologous recombination repair mutations, and the radionuclide therapy lutetium-177 PSMA-617 has reshaped the late-line setting since its approval in 2022. Against that backdrop, a durable complete response signal in even a small cohort of mCRPC patients is notable, because the disease is widely considered incurable at the metastatic stage. Syncromune is careful to frame the data as hypothesis-generating rather than confirmatory, and regulators will require randomised, controlled evidence before any curative positioning can be substantiated.

The company is now enrolling patients in the Phase 2a LEGION-100 trial (NCT06533644), focused specifically on mCRPC, across 24 cancer centres in the United States. International sites are expected to open in the near term. Syncromune remains privately held and has not disclosed its funding position or a timeline for a potential regulatory submission. Investors will focus on LEGION-100 response rates, the durability of complete responses in a larger cohort, and whether the systemic abscopal-type effect observed in Phase 1 is reproducible at scale.