Cancer of unknown primary (CUP) is heterogeneous and has a wide variety of clinical presentations and a poor prognosis in most patients, with a median overall survival of only 6 months. The development of molecular profiling contributes to precision
therapy, and targeted drugs and
immune checkpoint inhibitors (ICIs) greatly promote individualized treatment.
Case presentation: Here, we reported a case of an unfavorable subset of CUP who had a long time of survival after the
immunotherapy-prominent comprehensive treatment. A 48-year-old man presented with
back pain and a
cough. A diagnostic work-up showed bone marrow, multiple bones, and
lymph node metastasis. Lymph node pathology implies metastatic poorly differentiated
cancer. Next-generation sequencing (NGS) showed no special targets, but the
tumor proportion score (TPS) of
programmed death-ligand 1 (PD-L1) was 80% and the
tumor mutation burden (TMB) was 16.7 per million bases. After two cycles of
pembrolizumab 200 mg D1 plus nanoparticle
albumin-bound (
nab)-paclitaxel 200 mg D1&8 (q3w), PET-CT and bone marrow aspiration cytology showed a complete response (CR). Subsequently,
pembrolizumab alone was used for three months. The left inguinal lymph nodes showed new
metastasis. After two cycles of the combination treatment of
pembrolizumab and (
nab)-paclitaxel, a partial response (PR) was achieved. After seven months, retroperitoneal lymph nodes showed new
metastasis, and the sequential treatment with
radiotherapy and
pembrolizumab exhibited encouraging efficacy. To date, the patient has survived nearly 40 months with the combination
therapy.
Conclusions: The ICI-prominent comprehensive treatment provided clinical benefit for the reported case of CUP. Thus, CUP patients with markers of benefiting from
immunotherapy should be actively treated with
immunotherapy to improve their prognosis.