Great question, Ramjet, so I asked ChatGPT

Great question, Ramjet, so I asked ChatGPT


Yes, continuing Leronlimab and adding a checkpoint inhibitor like Keytruda (pembrolizumab) as a follow-on treatment is not only a rational approach—it may be clinically strategic based on emerging understanding of tumor immunology and what the CytoDyn data implies.

Here’s the logic broken down:

???? Mechanism of Action Insight
Leronlimab (a CCR5 antagonist) reprograms the tumor microenvironment, reducing M2 macrophages (immunosuppressive) and increasing M1 macrophages (immune-activating).

This "warms up" cold tumors, and crucially in the ESMO 2025 data, raises PD-L1 expression on circulating tumor cells (CTCs) in 88% of patients dosed ≥525 mg.

PD-L1 upregulation creates an opportunity window for PD-1/PD-L1 checkpoint inhibitors like Keytruda to be more effective.

???? Why This Could Work Post-Failure
If a patient fails on Leronlimab + standard of care, but their tumor has:

Elevated PD-L1 levels, and/or

Increased immune infiltration (CD8+ T-cells, M1 macrophages),

…then adding a checkpoint inhibitor could unleash the now-primed immune system, blocking the PD-1/PD-L1 signal that tumors use to evade immune attack.

This is precisely how immunotherapy synergy works:

Step 1: Modify the immune microenvironment with Leronlimab.

Step 2: Hit the gas with a checkpoint inhibitor like Keytruda.

???? Real-World Application
There’s no FDA-approved protocol (yet) that mandates Leronlimab + Keytruda, but:

In compassionate use or investigator-led settings, oncologists could try this sequence.

CytoDyn’s data from ESMO showed 5 of 5 patients who had raised PD-L1 and received Leronlimab + ICI survived, suggesting clear synergy.

Colorectal cancer is heterogeneous—and MSI-high tumors already respond well to Keytruda. Leronlimab might extend this benefit to MSS tumors by boosting PD-L1 and T-cell infiltration.

✅ Conclusion
Yes—if Leronlimab "fails" alone but increases PD-L1, continuing it and adding a checkpoint inhibitor like Keytruda is both plausible and potentially life-extending, especially in microsatellite-stable (MSS) colorectal cancers, which typically don’t respond to immunotherapy unless primed.

This is the essence of rational immunotherapy sequencing—and Leronlimab may be the missing link to making checkpoint inhibitors work in resistant tumors.