e15086 Background: Expanded access for DeltaRex-G, a tumor targeted retrovector encoding a CCNG1 inhibitor, is being studied for advanced cancers. Methods: 137 archived tumor specimens were analyzed with AI RNA sequencing to identify CCNG1 expression levels, reported as: Low = 17%, Medium-low = 17%-49%, Medium-high = 50%-83%, High = 83%. Nine patients with advanced solid malignancies, whose CCNG1 levels were identified, received DeltaRex-G (2-3 x 10e11 cfu/dose one to three times a week), either without an FDA-approved drug, or with an FDA-approved drug (“DeltaRex-G Plus”). Overall survival, duration of treatment, and responses were evaluated. Results: All analyzed tumors showed enhanced CCNG1 expression. Thirty (22%) tumors exhibited High CCNG1 expression, 48 (35%) showed Medium-High CCNG1 expression, 53 (39%) displayed Medium-Low CCNG1 expression, and six (4%) had Low CCNG1 expression. One hundred (73%) patients had metastatic disease, and 37 (27%) had localized disease. There was no correlation between CCNG1 expression and disease stage. Four patients with advanced pancreatic cancer (n = 1), Stage 1 HR+Her2+ invasive breast cancer (n = 1), Stage 1 triple negative breast cancer (n = 1), and squamous cell carcinoma of skin (n = 1), received DeltaRex-G alone or DeltaRex-G Plus between 2008 and 2021 and are alive 15, 3, 2.5, and 2.5 years since treatment initiation, respectively. Retrospective analysis of their respective tumors showed CCNG1 expression levels of 24%, 23%, 74%, and 40%. Three of the patients are in sustained remission and the patient with squamous cell carcinoma had a partial response. Of the five patients currently being treated with DeltaRex-G Plus: one patient with advanced breast cancer had a partial response (n = 1), one patient with advanced pancreatic cancer (n = 1) and three patients with soft tissue sarcoma (n = 3) had stable disease. Four of five patients had previously progressed with standard doses of chemotherapy. All patients are alive from 11 to 22 weeks since treatment initiation. No serious treatment-related adverse events have been reported. Conclusions: Taken together, the data shows that (1) 100% of 137 tumors tested have enhanced CCNG1 expression, further reinforcing the 2021 FDA-CBER authorization for use of DeltaRex-Plus, and (2) DeltaRex-G Plus is a promising therapy for advanced pancreatic cancer, sarcoma, and breast cancer. Randomized Phase 2/3 studies are warranted to confirm the efficacy and safety of DeltaRex-G Plus. Clinical trial information: NCT04091295 .