Greenwich LifeSciences Inc. (GLSI) had itself a day on Monday, with shares climbing and trading volume exploding to 2.804 million shares compared to the usual 81,850. The catalyst? Some genuinely encouraging news about the company's experimental breast cancer vaccine.

The biotech announced that its Phase 3 trial, dubbed FLAMINGO-01, delivered roughly 80% reduction in breast cancer recurrence rates among 220 patients in the open-label non-HLA-A*02 arm. For context, GLSI-100 is an immunotherapy designed to prevent breast cancer from coming back after treatment, which is obviously a big deal for patients who've already fought the disease once.

What's making investors particularly optimistic is that these results are tracking closely with the Phase 2b trial outcomes. In that earlier study involving HLA-A*02 patients, breast cancer recurrences dropped by up to 80%. Compare that to the 20-50% reduction you typically see with other approved products, and you can understand why the stock popped.

The company also shared that the first non-HLA-A*02 patient has now completed all 11 primary and booster vaccinations spanning the initial three years of treatment. That's a meaningful milestone, demonstrating that patients can stick with the full protocol.

Greenwich LifeSciences previously noted that immune response patterns before treatment, during the primary immunization series, and the safety profile for non-HLA-A*02 patients all look similar to what they observed in HLA-A*02 patients in both FLAMINGO-01 and the Phase 2b study. Consistency across different patient populations is exactly what you want to see in clinical trials.

Here's how the treatment works: Patients receive six GLSI-100 injections over the first six months, called the Primary Immunization Series, which gets them to peak immune protection. Then they get five booster shots every six months after that to maintain the immune response and extend protection over time.

The current non-HLA-A*02 dataset includes 250 patients who received GLSI-100, which is five times the roughly 50 patients treated in the Phase 2b trial. More patients means more data, and more data means greater confidence in the results.

Price Action: GLSI stock was up 8.76% at $11.67 on Monday.