If you have not read the original GLSI analysis, this article builds directly on that foundation. You can find the full breakdown of the company, trial structure, and valuation framework here: GLSI Life Science Data Breakdown and Stock Analysis.
In a previous article, we broke down Greenwich LifeSciences (NASDAQ: GLSI) from a stock and clinical perspective, focusing on trial structure, risk, and long-term valuation drivers. Since then, the company has released additional analysis that has sparked confusion around its Phase II and Phase III results — particularly the discussion of “100% prevention” versus an “80% reduction.”
This follow-up article clarifies what the data actually reveal, why the numbers appear different at first glance, and what investors should take away from the latest clinical update.
Phase IIb Results: What Was Actually Proven
The randomized Phase IIb trial of GLSI-100 demonstrated a strong and durable reduction in breast cancer recurrence compared with placebo. Across longer-term follow-up, the treated group showed approximately an 80 percent or greater reduction in recurrence rates.
That level of efficacy already places GLSI-100 above most existing adjuvant therapies, which typically reduce recurrence risk by roughly 20 to 40 percent.
The often-cited “100% disease-free survival” figure came from early presentations and sub-analyses involving smaller patient subsets and shorter follow-up windows. In those specific groups, no recurrences were observed during the observation period.
However, this was never the overall Phase IIb outcome across the full randomized cohort. The correct interpretation of the Phase IIb data is a substantial reduction in recurrence risk — not absolute or permanent prevention.
Phase III (FLAMINGO-01): What Has Been Reported So Far
Early observations from the ongoing Phase III FLAMINGO-01 trial are consistent with the Phase IIb findings. In the open-label, non-HLA-A*02 arm, preliminary analysis has shown approximately an 80 percent reduction in recurrence trends to date.
It is important to emphasize that Phase III results are still early and not yet based on final, event-driven comparisons. As follow-up continues and more data mature, results will naturally stabilize.
Crucially, this does not represent a step backward from Phase II. Instead, it reflects the expected transition from smaller datasets to broader populations with longer observation periods.
Baseline Recurrence Risk: The Missing Context
Understanding recurrence reduction requires context around baseline risk. Patients in GLSI trials are not untreated. They already receive standard of care, which may include surgery, radiation, and endocrine therapy.
Even with standard treatment, recurrence risk remains meaningful. For early-stage, hormone-receptor–positive breast cancer, the typical recurrence risk is:
- Approximately 10 to 30 percent over 5 to 10 years
- Higher-risk subgroups may exceed 30 percent with longer follow-up
- An annualized recurrence rate of roughly 1 to 3 percent per year
As a simplified benchmark, prevention trials often assume a cumulative recurrence risk of around 20 percent over several years.
What an 80% Reduction Actually Means
An 80 percent reduction in recurrence does not mean recurrence drops to 20 percent. It means recurrence is reduced by 80 percent relative to the baseline risk.
Using a 20 percent baseline as an example:
- Baseline recurrence risk: 20 percent
- 80 percent relative reduction
- Implied residual recurrence risk: approximately 4 percent
That difference — from 20 percent down to roughly 4 percent — would represent a major clinical advance if confirmed durably in Phase III.
Why the “100% Prevention” Narrative Persisted
The idea of 100 percent prevention came from specific subgroups, limited follow-up periods, and intervals where no recurrence events were observed. As datasets expand and follow-up lengthens, results naturally converge toward more statistically stable outcomes.
This normalization toward an 80 percent relative reduction is expected and does not imply that the therapy has become less effective.
Why an 80% Reduction Still Matters
Most approved breast cancer adjuvant therapies reduce recurrence risk by 20 to 40 percent. A durable 80 percent reduction would place GLSI-100 in best-in-class territory, particularly as a prevention-focused therapy.
From a regulatory standpoint, consistent relative risk reduction matters far more than claims of perfect prevention. This is why the program remains in Phase III and continues without safety-related trial modifications.
Bottom Line
Phase IIb never demonstrated universal 100 percent prevention, and Phase III has not regressed from earlier findings. The consistent takeaway across both phases is a substantial reduction in recurrence risk of roughly 80 percent.
With baseline recurrence rates commonly ranging from 10 to 30 percent, this implies a treated recurrence rate in the low single digits if results hold over longer follow-up. If Phase III confirms this effect durably, the clinical and valuation implications for GLSI would be significant.