Everolimus in CDK12-Deficient Metastatic Colorectal Cancer (EVER-RECODE)

Inclusion Criteria:

1. Ability to understand and voluntarily sign an ethics committee-approved informed consent form and willingness to comply with scheduled visits, treatment plans, laboratory tests, and other study procedures.
2. Age 18 to 80 years (inclusive) at the time of signing informed consent; male or female.
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
4. Estimated life expectancy ≥12 weeks.
5. CDK12 deficiency confirmed by immunohistochemistry (IHC).
6. Histologically confirmed metastatic colorectal cancer with documented disease progression after prior standard systemic antitumor therapies, including but not limited to oxaliplatin, fluoropyrimidine, and irinotecan.

   o Patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) tumors must have experienced disease progression following anti-PD-1/PD-L1 therapy.
7. At least one measurable lesion according to RECIST version 1.1, defined as:

   * Non-nodal lesions ≥10 mm in longest diameter by CT scan (slice thickness ≤5 mm);
   * Malignant lymph nodes with short axis ≥15 mm by CT scan (slice thickness ≤5 mm recommended).
8. Adequate organ function meeting all of the following criteria:

   Hematologic (without growth factor support or transfusion within 7 days prior to testing):
   * Absolute neutrophil count ≥1.5 × 10⁹/L
   * Platelet count ≥75 × 10⁹/L
   * Hemoglobin ≥90 g/L

   Biochemical:
   * Total bilirubin ≤1.5 × upper limit of normal (ULN)
   * AST and ALT ≤2.5 × ULN
   * Serum creatinine ≤1.5 × ULN or creatinine clearance ≥50 mL/min (calculated using Cockcroft-Gault formula)

   Coagulation:
   * International normalized ratio (INR) ≤1.5
   * Activated partial thromboplastin time (aPTT or PTT) ≤1.5 × ULN
9. Absence of high-risk conditions, including:

   * Active or major cardiovascular events within 6 months (e.g., myocardial infarction, severe heart failure, stroke);
   * Severe pulmonary dysfunction requiring long-term oxygen therapy or interstitial lung disease/pulmonary fibrosis;
   * Active uncontrolled infection (including uncontrolled HBV, HCV, HIV, or tuberculosis);
   * Other active malignancies within 5 years, except those treated with curative local therapy.
10. For participants of childbearing potential:

    * Must agree to use effective contraception during the study and for 120 days after completion;
    * Negative serum pregnancy test within 7 days prior to enrollment;
    * Not breastfeeding.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded:

1. Untreated or active central nervous system (CNS) metastases. Patients with a history of leptomeningeal metastases or current leptomeningeal disease.
2. Receipt of systemic antitumor therapy within 4 weeks prior to initiation of study treatment.

   * For prior small-molecule targeted therapy: the interval between the end of prior therapy and first study dose must be ≥5 half-lives of the drug or ≥7 days, whichever is longer.
   * For prior traditional Chinese antitumor medicines: ≥2 weeks washout is required.
3. Palliative radiotherapy to non-target lesions, radioactive seed implantation, radiofrequency ablation, or similar local therapy within 28 days prior to first study dose.
4. Toxicities or complications from prior therapies that have not recovered to NCI-CTCAE grade ≤1 or to eligibility-specified levels.

   o Patients with stable grade ≤2 toxicities may be enrolled at investigator discretion if no safety risk exists (e.g., immune checkpoint inhibitor-related type 1 diabetes or hypothyroidism controlled with hormone replacement therapy).
5. Within 28 days prior to first study dose: inability to swallow oral medication, chronic diarrhea, active gastroenteritis, gastrointestinal perforation, prior major gastrointestinal resection, colitis, or other conditions that may impair drug administration or absorption.
6. Clinically symptomatic moderate or severe ascites requiring therapeutic paracentesis or drainage within 2 weeks prior to study treatment.

   * Small asymptomatic ascites detected by imaging is allowed.
   * Uncontrolled or moderate-to-large pleural effusion or pericardial effusion.
7. Evidence of intestinal obstruction or signs/symptoms of obstruction at baseline.

   * Patients who underwent surgery with complete resolution of obstruction may be screened.
   * Presence of an indwelling intestinal stent at screening.
8. Uncontrolled or severe cardiovascular disease, including:

   * Severe or unstable congestive heart failure (NYHA class II-IV)
   * Myocardial infarction within 6 months prior to first dose
   * Unstable angina within 1 month prior to treatment
   * Unstable arrhythmia
9. History of or concurrent malignancies other than colorectal cancer, unless in complete remission for ≥5 years prior to screening and not requiring ongoing therapy, except:

   * Basal cell carcinoma of the skin
   * Superficial bladder cancer
   * Cutaneous squamous cell carcinoma
   * Cervical carcinoma in situ
   * Localized prostate cancer
   * Ductal carcinoma in situ after curative surgery
   * Non-metastatic prostate or breast cancer receiving hormone therapy
10. Severe infection within 28 days prior to first dose, including infections requiring hospitalization, bacteremia, or severe pneumonia.

    * Active infection requiring therapeutic intravenous antibiotics within 2 weeks prior to treatment.
    * Prophylactic antibiotics (e.g., for urinary tract infection prevention) are permitted.
11. Active hepatitis B infection defined as:

    o Positive HBsAg AND HBV DNA ≥10,000 copies/mL (≥2,000 IU/mL).

    Active hepatitis C defined as:

    o Positive HCV antibody AND detectable HCV RNA.
12. Active pulmonary tuberculosis within 1 year prior to enrollment, or history of active tuberculosis \>1 year prior without appropriate standard treatment.
13. Known immunodeficiency, including HIV positivity, congenital or acquired immunodeficiency disorders, or history of organ transplantation.
14. Active autoimmune disease, including but not limited to systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, myasthenia gravis, or requirement for long-term systemic immunosuppressive therapy.
15. Concomitant use of strong CYP3A4 inhibitors or inducers that cannot be discontinued ≥7 days prior to first dose (e.g., ketoconazole, itraconazole, clarithromycin, rifampin, carbamazepine, phenobarbital).
16. Active severe oral mucosal disease or recurrent oral ulceration.

    o History of ≥grade 2 stomatitis that has not recovered to CTCAE grade ≤1.
17. Active dermatologic disorders (e.g., psoriasis, severe eczema, chronic pruritus) or prior ≥grade 2 drug-related skin reactions not fully resolved.
18. Prior treatment with everolimus and:

    * Development of ≥grade 3 drug-related toxicity, OR
    * Discontinuation due to resistance or lack of efficacy.
19. Known hypersensitivity to everolimus or any of its metabolites.
20. Pregnant or breastfeeding women, or women planning pregnancy during the study period.
21. Uncontrolled psychiatric illness, known alcohol or drug abuse, incarceration, or other conditions that may interfere with study compliance.
22. Any other condition that, in the investigator's judgment, may increase study risk, interfere with study outcomes, or make the participant unsuitable.
23. Inability to understand study conditions and objectives or refusal to sign informed consent.