Tadalafil augments tumor specific immunity in patients with head and neck squamous cell carcinoma.
Level 2 - randomized trial
Randomized, double-blind, placebo-controlled phase II clinical trial.
PubMed 25564570 · doi:10.1158/1078-0432.CCR-14-1716
What was done
A randomized, prospective, double-blind, placebo-controlled phase II clinical trial evaluated the in vivo effects of systemic phosphodiesterase 5 (PDE5) inhibition with tadalafil versus placebo on immune function and myeloid-derived suppressor cells (MDSC) in patients with head and neck squamous cell carcinoma (HNSCC).
What was found
Tadalafil significantly improved immune parameters compared to placebo: - Ex vivo T-cell expansion showed a mean 2.4-fold increase versus 1.1-fold in controls (P = 0.01). - Peripheral MDSC numbers decreased to a mean 0.81-fold change versus a 1.26-fold change in controls (P = 0.001). - General immunity increased as measured by delayed-type hypersensitivity response (P = 0.002). - Tumor-specific immunity in response to HNSCC tumor lysate was augmented (P = 0.04).
Why it matters
This trial demonstrates in humans that the PDE5 inhibitor tadalafil can reverse tumor-mediated immune suppression by reducing MDSC counts and augmenting tumor-specific immunity.
Limits
The abstract does not report the sample size (n), drug dosage, duration of therapy, patient baseline characteristics, or clinical survival endpoints (e.g., progression-free or overall survival).
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