Syncromune has reported encouraging long-term survival results for its investigational SYNC-T Therapy SV-102, with 80% of patients with metastatic prostate cancer alive two years after treatment in a Phase 1 clinical trial. The updated findings showed that three of six patients who achieved a complete response remained disease-free for more than two years, while median overall survival had not been reached after nearly 30 months of follow-up. The results suggest that combining localized tumor destruction with multiple immunotherapies may generate durable anticancer activity, although the 15-patient study cannot establish a survival benefit over existing treatments.
Presented at the European Society for Medical Oncology Congress 2026, the findings provide further support for Syncromune’s ongoing Phase 2a LEGION-100 trial in metastatic castration-resistant prostate cancer. The privately held biotechnology company is investigating whether its locally administered treatment can stimulate immune responses against cancer deposits throughout the body, including tumors that have not been directly treated.
What did the Phase 1 SYNC-T prostate cancer trial reveal about two-year overall survival?
The open-label, single-arm Phase 1 study, registered as NCT05544227, enrolled 15 patients with metastatic prostate cancer. Ten participants had metastatic castration-resistant prostate cancer, while five had metastatic hormone-sensitive prostate cancer and had declined androgen deprivation therapy.
As of the April 1, 2026, data cutoff, median follow-up had reached 29.6 months. Twelve of the 15 treated patients were alive at 24 months, producing a reported two-year overall survival rate of 80%.
Median overall survival had not been reached in the overall study population, with a reported 95% confidence interval extending from 27.9 months to not reached. This means that fewer than half of the participants had died during the available observation period, rather than establishing that patients could survive indefinitely.
Survival differed between the two disease subgroups. Among the ten patients with metastatic castration-resistant prostate cancer, median overall survival was 27.9 months, while the 24-month survival rate was 70%.
No deaths were reported among the five participants with metastatic hormone-sensitive disease, corresponding to a 100% two-year survival rate in that subgroup. However, the patients had different disease characteristics and treatment histories, making comparisons between these small groups inappropriate.
The overall survival findings are encouraging, particularly given the advanced cancer setting. Nevertheless, the absence of a randomized control group prevents researchers from determining how much of the observed survival was attributable to SYNC-T rather than patient selection, disease biology or other treatments.
How durable were complete responses to SYNC-T Therapy SV-102 in metastatic prostate cancer?
Syncromune previously reported an objective response rate of 87% in the Phase 1 study, with six of the 15 participants achieving a complete response. The complete response rate was therefore 40%, while the objective response rate included patients with either complete or partial tumor responses.
The updated analysis focused on the durability of those responses. Three of the six complete responders remained disease-free, with follow-up periods ranging from 26.5 to 35.3 months after treatment.
These observations are important because durable tumor control remains a major challenge in metastatic prostate cancer, particularly when disease has progressed despite hormonal treatment. Continued absence of detectable disease over more than two years warrants further investigation into whether the treatment can generate lasting immune activity.
However, complete response and disease-free status do not necessarily indicate permanent eradication of cancer. Microscopic disease may remain undetectable, and recurrence can occur after prolonged periods without radiographic evidence of tumors.
The company has suggested that durable disease-free responses could eventually support investigation of potentially curative outcomes. Such a possibility remains hypothetical and would require substantially larger studies, longer observation and careful documentation of recurrence patterns.
The three complete responders who were no longer classified as disease-free also illustrate why response durability must be evaluated across the entire treated population. A high initial response rate does not automatically translate into lasting disease control for every patient.
How does Syncromune’s tumor-directed immunotherapy seek to attack untreated metastases?
SYNC-T Therapy SV-102 combines image-guided tumor cryolysis with local administration of four immune-modulating agents. The approach is intended to generate an immune response using antigens released from a patient’s own cancer cells.
During treatment, clinicians insert a specialized needle-like device into a selected tumor lesion. The device partially freezes and thaws a small portion of the tumor, disrupting cancer cells and releasing tumor-associated proteins that may help the immune system recognize malignant tissue.
Immediately afterward, clinicians administer SV-102 directly into the treated lesion through the same device. The infusion takes approximately five minutes, and the procedure is designed for outpatient administration.
The treatment contains abazistobart, an anti-PD-1 antibody; futermestotug, an anti-CTLA-4 antibody; ciltistotug, a CD40 agonist; and sitmutolimod, a TLR9 agonist. These agents target complementary mechanisms involved in immune activation and regulation.
The combined strategy aims to concentrate immune stimulation within the tumor and its draining lymph nodes. By presenting patient-specific cancer antigens alongside immune-modulating medicines, researchers hope to encourage immune cells to recognize malignant tissue beyond the original treatment site.
Investigators reported that follow-up imaging in some participants showed regression of distant metastases that had not received direct treatment. This observation is consistent with a possible systemic immune response, although the uncontrolled study cannot conclusively establish the mechanism responsible.
Unlike conventional systemic immunotherapy, the platform seeks to coordinate several immunological interventions at a tumor site. Whether this approach can deliver superior efficacy or safety compared with established treatment combinations remains unknown.
What did the Phase 1 safety findings show about localized multi-target cancer immunotherapy?
Syncromune reported that SYNC-T Therapy SV-102 was generally well tolerated during the Phase 1 study. Approximately 95% of treatment-emergent adverse events were classified as Grade 1 or Grade 2, indicating predominantly mild or moderate severity.
No Grade 4 or Grade 5 adverse events were reported, and investigators observed no Grade 3 or Grade 4 immune-related toxicities. These findings provide preliminary reassurance because the treatment combines several agents capable of influencing immune responses.
However, the company’s summary does not establish that all adverse events were minor or that serious complications cannot occur. A treatment involving multiple immune-modulating mechanisms requires careful assessment of inflammatory reactions, organ-specific toxicities and delayed immune-related effects.
The limited patient population substantially restricts the ability to detect uncommon complications. Moreover, the safety findings cannot demonstrate that localized treatment is less toxic than conventional systemic immunotherapy without direct comparative evidence.
Patients in the Phase 1 study could receive as many as 12 treatment cycles, with each cycle targeting a single lesion approximately every four weeks. Safety monitoring in larger studies will therefore need to examine the effects of repeated procedures and cumulative exposure. Determining whether localized delivery can maintain adequate immune activation while limiting systemic adverse effects will be central to evaluating the platform’s clinical usefulness.
Why is metastatic castration-resistant prostate cancer a priority for further SYNC-T development?
Metastatic prostate cancer occurs when malignant cells spread beyond the prostate, commonly involving bones and lymph nodes. Treatment often begins with androgen deprivation therapy, which reduces testosterone signaling that helps drive prostate cancer growth.
Many patients eventually develop castration-resistant disease, meaning the cancer continues progressing despite suppression of androgen activity. At that stage, treatment decisions may involve androgen receptor pathway inhibitors, chemotherapy, radiopharmaceuticals and selected targeted therapies.
Although these treatments can extend survival and improve disease control, patients with advanced or treatment-resistant disease continue to face substantial clinical challenges. Additional therapeutic approaches capable of producing durable responses therefore remain an important research priority.
Syncromune is focusing its next development stage on metastatic castration-resistant prostate cancer rather than the mixed population enrolled in the initial Phase 1 study. This more defined population should help investigators better characterize treatment activity in a clinically challenging setting.
The company’s broader research strategy also includes assessing whether SYNC-T can be adapted to other solid tumors. However, the prostate cancer findings do not establish effectiveness in unrelated cancer types, even when similar immune pathways are involved. Further development will require standardized response assessments, longer survival follow-up and careful consideration of how the therapy could fit alongside established prostate cancer treatments.
What comes next for the Phase 2a LEGION-100 trial at U.S. cancer centers?
The ongoing Phase 2a LEGION-100 trial, registered as NCT06533644, is evaluating SYNC-T Therapy SV-102 in patients with metastatic castration-resistant prostate cancer. Syncromune reports that enrollment is underway at 24 cancer centers across the United States, with additional international locations expected to become available.
The study is intended to expand the clinical evidence beyond the small Phase 1 population and provide more information about treatment responses, their durability and safety. Findings from a broader group of patients should also help determine whether the promising signals observed in the initial trial are reproducible.
Although Phase 2a development represents an important step, additional controlled research may be necessary to establish whether SYNC-T improves survival or other clinically meaningful outcomes compared with standard treatment. Regulators will also need adequate evidence concerning manufacturing, procedural consistency and the safety of the combined drug-device approach.
The reported 80% two-year survival rate and prolonged complete responses provide encouraging reasons to continue investigating the platform. Nevertheless, the results should be interpreted as early evidence of potential activity rather than proof of a curative treatment.
For patients with advanced metastatic prostate cancer, SYNC-T offers a distinctive experimental strategy aimed at mobilizing the immune system against tumors throughout the body. Its ultimate therapeutic value will depend on whether larger studies confirm durable clinical benefits with an acceptable safety profile.
