Low dose cyclophosphamide has also been shown to enhance an anti-cancer immune response. In a study published by Scurr, et al. in Clinical Cancer Research, Nov. 15, 2017, they showed that low dose cyclophosphamide induced an anti-tumor T cell response in metastatic colorectal cancer that was associated with increased survival. Levy, et al. from Johns Hopkins published in The Journal of Pharmacology and Experimental Therapeutics (330:596-601, 2009) that low dose cyclophosphamide unmasked the anti-metastatic effect of local tumor cryoablation. This study showed that cryoablation with cyclophosphamide, but not surgery, demonstrated a systemic anti-cancer immune response. In the animal model of metastatic colorectal cancer, survival rates achieved by using cyclophosphamide plus cryoablation was shown to be 50%, compared to 0% when combined with surgery or versus cryoablation alone. One common dosing regimen is to use 50mg by mouth every other day. This has little, if any toxicity and high ease of use, since it is in a pill form. We often use this regimen ourselves, especially when combined with cryoablation.

Reference: Jason R. Williams, 15 Oct 2019, The Immunotherapy Revolution: The Best New Hope For Saving Cancer Patients’ Lives,