Evaluation of the Effect of Cordycepin on CD8+ Lymphocytopenia in Patients With Solid Tumors

Inclusion Criteria: 1. Age ≥ 18 years; 2. Participants with solid malignant tumors, with confirmed pathological diagnosis or medical history; they have completed radiotherapy and/or chemotherapy more than six months ago; and peripheral blood CD8+ absolute count (blood drawn before 10:00 AM) below the lower reference limit (LRL); 3. No treatment with immunomodulatory or immunosuppressive agents within the past 2 weeks prior to enrollment; 4. ECOG performance status score of 0-1, with an estimated life expectancy of ≥ 3 months; 5. AST and ALT ≤ 3.0 times the upper limit of normal (ULN) within one week prior to study enrollment; serum creatinine ≤ 2 times ULN; 6. Ability to understand the study and voluntarily provide written informed consent. Exclusion Criteria: 1. History of uncontrolled epilepsy, central nervous system (CNS) disease, or mental disorders, as determined by the investigator to be clinically significant and potentially interfere with the participant's ability to provide informed consent or comply with medication; 2. Significant (i.e., active) cardiovascular disease, including symptomatic coronary heart disease, congestive heart failure classified as New York Heart Association (NYHA) Class II or worse, or serious arrhythmias requiring pharmacological intervention, or history of myocardial infarction within the past 12 months; 3. Known active serious infections, or in the investigator's opinion, presence of major hematological, renal, metabolic, gastrointestinal, or endocrine dysfunction, or other serious, uncontrolled comorbidities; 4. History of allergy to fungi, or to any of the following components: Cordyceps militaris extract powder, D-mannitol, maltitol, microcrystalline cellulose, or magnesium stearate; 5. History of immunodeficiency, including HIV positive status, or diagnosis with other acquired or congenital immunodeficiencies, or a history of organ transplantation, or immunological disorders requiring long-term oral corticosteroid treatment; 6. Acute gout flare 7. Any other condition deemed unsuitable for enrollment by the investigator.