Due to the company's development strategy adjustment, Innovent Biologics has decided not to continue this study after consultation with investigators.

The purpose of this study is to evaluate the safety and efficacy of IBI318 monotherapy for relapsed/refractory extranodal NK/T cell lymphoma (nasal type).

Inclusion Criteria:

1. Histologically diagnosed as extra-nodal NK/T cell lymphoma (nasal type) according to WHO 2016 criteria;
2. Refractory and relapsed ENKTL patients, being relapsed is defined as re-occurrence of the same lymphoma lesions at the primary site or new sites after complete response (CR); being refractory is defined as having any of the following conditions: evaluated as stable disease (SD) or progression disease (PD) after 2 cycles of treatment; not being able to achieve partial response (PR) after 4 cycles of treatment; not being able to achieve complete response (CR) after 6 cycles of treatment. Patients that did not achieve remission, or relapsed/progressed after autologous stem cell transplantation (ASCT) could also be enrolled.
3. Patients must have received asparaginase-based chemotherapy previously (patients with phase I/II disease must have received radiotherapy previously).
4. With measurable foci, defined as: lymph nodes with long diameters>15mm，extra-nodal foci>10mm on CT scan;
5. ECOG PS (Eastern Cooperative Oncology Group Performance Status) point 0 or 1;

Exclusion Criteria:

1. Invasive NK cell leukemia;
2. Primary CNS lymphoma or CNS-involved lymphoma;
3. Patients with hemophagocytic syndrome;
4. Patients with lymphoma invading large pulmonary vessels;
5. Patients primarily resistant to anti-PD1,PD-L1,PD-L2 antibodies (generally considered as those received anti- PD1,PD-L1,PD-L2 antibodies as monotherapy or in combination with chemotherapy, but did not achieve PR or CR in non-maintenance treatment).