PD-1 antibody therapy combined with radiotherapy for early extranodal NK/T‑cell lymphoma

Inclusion Criteria:

* The subject has histopathologically confirmed extranodal NK/T-cell lymphoma, nasal type (according to the 2022 WHO classification).
* No prior history of anti-lymphoma therapy.
* Age ≥ 18 years.
* Life expectancy \> 3 months.
* Ann Arbor stage I-II.
* At least one measurable/evaluable disease site confirmed by diagnostic biopsy prior to the initiation of treatment.
* Eastern Cooperative Oncology Group (ECOG) performance status score of 0-2.
* Signed informed consent form (ICF).
* Willingness and ability to comply with the study protocol.
* Sufficient bone marrow, hepatic, and renal function, defined as:

  1. Absolute neutrophil count (ANC) \> 1,000/μL
  2. Platelet count \> 50,000/μL
  3. Hemoglobin \> 9 g/dL
  4. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \< 3× upper limit of normal (ULN)
  5. Serum total bilirubin \< 1.5 × ULN (patients with Gilbert's syndrome are eligible)
  6. Serum creatinine \< 2 × ULN or creatinine clearance \> 50 mL/min
* Availability of tumor tissue samples (preferably fresh tissue; archived tissue samples are acceptable).
* For women of childbearing potential, agreement to use adequate contraception to avoid pregnancy during the study treatment period.
* For male, agreement to remain abstinent or use a barrier method of contraception.

Exclusion Criteria:

* Advanced-stage disease (Ann Arbor Stage III-IV).
* Nonnasal-type NKTCL.
* A history of autoimmune disease requiring systemic treatment (i.e., with disease-modifying antirheumatic drugs, corticosteroids, or immunosuppressants) within the past 2 years, including but not limited to myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, antiphospholipid antibody-associated vasculopathy, granulomatosis with polyangiitis (Wegener's), Sjögren's syndrome, Guillain-Barré syndrome, multiple sclerosis, vasculitis, or glomerulonephritis.

The following conditions are permissible for enrollment: patients with autoimmune hypothyroidism or type 1 diabetes receiving stable treatment; hormone replacement therapy (e.g., levothyroxine, insulin, or supplementation with physiological hormones for adrenal or pituitary insufficiency) is not considered systemic therapy and is allowed.

* A history of other invasive malignancies within the past 3 years that has not been treated with curative intent or is currently receiving anticancer therapy (including hormonal therapy for breast or prostate cancer).
* A history of (non-infectious) pneumonia requiring corticosteroid therapy; or clinical evidence of interstitial lung disease or active, non-infectious pneumonia.
* Active infections requiring systemic treatment, including:

  1. A known history of active tuberculosis;
  2. Positive results for HBsAg, HCV, or HIV; HBV seropositivity is permitted only if HBV DNA \< 1000 IU/mL;
  3. Active viral infections other than hepatitis B and C (e.g., herpes zoster).
* Severe cardiovascular disease, including myocardial infarction, unstable arrhythmia, or unstable angina occurring within the past 3 months.
* Prior treatment with anti-PD-1, anti-PD-L1, or anti-PD-L2 agents.
* Administration of live-attenuated vaccines within 4 weeks prior to the initiation of study treatment; patients are prohibited from receiving live-attenuated vaccines during the study period, including influenza vaccines.
* Use of systemic immunosuppressive agents within 2 weeks prior to the initiation of study treatment, or planned use of such agents during the study period, including cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor (anti-TNF) drugs.
* Evidence of central nervous system involvement.
* A history of allogeneic tissue/solid organ transplantation.
* A history of severe hypersensitivity reactions (Grade ≥ 3) to PD-1 monoclonal antibodies and/or their excipients, or to gorlitinib and/or its excipients.
* Any other factors judged by the investigator to potentially affect compliance with the study protocol.