Combining PARP inhibition and immune checkpoint blockade in ovarian cancer patients: a new perspective on the horizon?

Immune checkpoint inhibitors (ICIs) have completely reshaped the treatment of many malignancies, with remarkable improvements in survival outcomes. In ovarian cancer (OC), however, this emerging class of drugs has not yet found a favorable use due to results from phase I and II studies, which have not suggested a substantial antitumoral activity of these agents when administered as monotherapy. Robust preclinical data seem to suggest that the combination ICIs with poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) may result in a synergistic activity; furthermore, data from phase II clinical studies, evaluating this combination, have shown encouraging outcomes especially for those OC patients not suitable for platinum retreatment. While waiting for ongoing phase III clinical trial results, which will clarify the role of ICIs in combination with PARPis in the newly diagnosed OC, this review aims to summarize the preclinical data and clinical evidence available to date.

•

Preclinical data indicate that PARPis exhibit immune modulating properties.

•

The combination of PARPi with ICIs displays significant synergistic activity in preclinical models.

•

Phase I and II clinical trials showed encouraging results for this combination, especially in platinum-resistant OC.

•

Four ongoing phase III trials exploring the combination in first-line setting will delineate the role of immunotherapy in OC.

A phase 2 study of temozolomide in pretreated metastatic colorectal cancer with MGMT promoter methylation

Background:

Presently, few options are available for refractory colorectal cancer (CRC). O6-methyl-guanine-DNA-methyltransferase (MGMT) promoter methylation is a frequent and early event in CRC tumourigenesis. This epigenetic silencing is a predictor of response to the alkylating drug temozolomide in glioblastoma. Preclinical evidences and some case reports showed temozolomide activity in CRC with MGMT silencing, but the available data from clinical trials are inconsistent.

Methods:

This was a multicentre, phase 2 trial, planned according to a two-stage Simon’s optimal design to investigate activity and safety of temozolomide in refractory CRC harbouring MGMT promoter methylation. The primary end point was overall response rate (ORR). Patients who failed two or more prior treatments received temozolomide at a dose of 150–200 mg m⁻² per day on days 1–5 every 28 days.

Results:

From July 2012 to June 2016, 225 patients were screened, 80 showed MGMT promoter methylation and 41 were enrolled. Overall response rate was 10% and disease control rate was 32%. Median progression-free survival and overall survival were 1.9 and 5.1 months, respectively.

Conclusions:

Temozolomide showed a modest activity in this heavily pretreated population and the study did not meet its primary end point. The role of temozolomide in CRC remains still controversial and further research is warranted.