this is a phase II, open-label study, to see whether the combination of Niraparib and Sintilimab is effective and safe to treat recurrent/metastatic nasopharyngeal carcinoma.~we will enroll patients who are histologically confirmed recurrent or metastatic nasopharyngeal carcinoma (including recurrence and metastasis after radiotherapy, or a condition not suitable for surgery and radiotherapy judged by investigator)~≥ 1L of platinum-based chemotherapy, at least 1 measurable lesion (RECIST 1.1), ECOG 0-1.~the study is designed to contain 2 cohorts: cohort A PD-(L)1 naive and cohort B PD-(L)1 previously treated patients, simon 2-steps design for each cohort, that is: for cohort A, first step will enroll 23 patients, if CR/PR patients ≥3， then go to the second step, continue to enroll 39 patients, otherwise this cohort ends. for cohort B, first step enroll 20 patients, if CR/PR patients ≥1，then continue to enroll 17 patients, otherwise the cohort ends.~Niraparib is a type of drug called a PARP inhibitor, which blocks DNA (the genetic material of cells) damage from being repaired or may prevent damage from occurring in the first place. In cancer treatment, inhibiting PARP may help kill cancer cells by not allowing the cancer cells to repair its DNA damage or prevent DNA damage associated with nasopharyngeal carcinoma from occurring.~The FDA has not approved niraparib for nasopharyngeal carcinoma, but it has been approved for other uses.
this study is aimed to evaluate the efficacy and safety of the combination of Niraparib and Sintilimab in the treatment of recurrent/metastatic nasopharyngeal carcinoma