Increased numbers of tumour infiltrating T‑cells have long been associated with a better prognosis in ovarian cancer, which has led to the general assumption of a relevant impact of T‑cellular anti-tumour immunity in this disease. As a consequence of this knowledge, a multitude of immunologic therapies has emerged over the past years. Although some reports could evidence a successful induction of anti-tumour T‑cells, in general, these attempts did not translate into clinically significant activity. As has already been shown in other tumour entities, immune checkpoint blockade – mainly antibodies directed against PD-1 and PD-L1 – could possibly become a real “game changer” in ovarian cancer in the future.
Background: The prognostic significance of tumour infiltrating T‑cells (TILs) in the setting of advanced ovarian cancer (stages III and IV) was already described as early as 2003. Zhang and colleagues analysed 174 patients and evidenced that the presence of TILs was associated with a significantly longer overall survival (OS) with a 5-year OS of 38 % in contrast to only 4.5 % in the cohort without TILs. These data have been corroborated in several further studies and have been summarized in a meta-analysis including 1815 patients. By further characterizing TILs, the positive prognostic impact could be attributed to the subgroup of CD8 positive intratumoural T‑cells. Therefore it can be hypothesized that the increased presence of TILs is caused by immunologic recognition of aberrant tumour cells, which ultimately results in improved immunologic tumour control.