In a clinical trial reported by Siena et al (12) aimed to assess the efficacy and safety of combination treatment with lenalidomide and cetuximab in KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog)-mutant metastatic colorectal cancer patients, we assessed 25 different subpopulations of CD45+ immune cells (T cells, B cells, and NK cells) in this patient population that does not have confounding hematological abnormalities. The gene discussed is KRAS; the disease is metastatic colorectal cancer.