Thymulin improves cancer immunotherapy in aged mice
Daily injections for four weeks improved tumor control and survival in aged mice with breast tumors, with minimal effects in young mice.
Limit: Survival reflected euthanasia thresholds for tumor size or severe illness, rather than natural death
Edited by Boris Djordjevic · AgingResearch.News
Female mice aged 65–75 weeks and young mice aged 8–12 weeks received implanted breast tumors in experiments testing thymulin, a small protein made by the thymus, an immune-system organ. Researchers gave daily injections of 1.5 milligrams per kilogram of body weight for four weeks, starting the day after tumor implantation.
Thymulin delayed tumor growth and improved survival in aged mice compared with control injections, with minimal effects in young mice. It reduced the frequency of myeloid cells, a group of immune cells, producing inflammatory signals inside tumors. It also strengthened cancer-fighting T-cell activity in aged mice. An antibody targeting PD-L1, an immune-regulating protein, had no effect on tumor growth or survival alone in aged mice. Combining it with thymulin improved tumor control and prolonged survival in an age-dependent manner.
Why it matters
Chronic inflammation increases with age and contributes to cancer progression and resistance to therapy. The authors suggest thymulin as a potential strategy to improve cancer immunotherapy in older people.
Caveats
The cancer-treatment results came from implanted tumors in mice, not a trial in people. Mice were euthanized when tumors reached 15 millimeters or they became severely ill.
The paper
Thymulin restrains age-associated myeloid inflammation and enhances cancer immunotherapy
University of Southern California
Nature Communications, Jul 21, 2026, Open access