Olaparib in metastatic prostate cancer: added benefit for certain patients

Olaparib is approved for several therapeutic indications. In an early benefit assessment, the German Institute for Quality and Efficiency in Health Care (IQWiG) investigated whether olaparib, in combination with abiraterone and prednisone or prednisolone, provides added benefit over the appropriate comparator therapy (ACT) in adults with metastatic castration-resistant prostate cancer (mCRPC) in whom chemotherapy is not indicated.

In comparison with the ACT, the Institute found a hint of minor added benefit in treatment-naive patients under 65 years of age, and a hint of lesser benefit in treatment-naive older patients. For pretreated patients, an added benefit is not proven due to a lack of relevant data.

Pretreatment and age matter

The Federal Joint Committee (G-BA) distinguished between two groups of patients. For adults with treatment-naive mCRPC, the ACT is treatment of physician's choice. In adults with pretreated mCRPC, treatment with olaparib should be compared with individualized treatment, taking into account prior therapy and BRCA1/2 mutation status.

For treatment-naive patients, the drug manufacturer used data from PROpel, a double-blind randomized controlled trial comparing olaparib in addition to abiraterone and prednisone or prednisolone with abiraterone and prednisone or prednisolone. At the start of the study, patients had disease progression despite medical or surgical castration, which had to continue throughout the study. However, it is not clear from the study documentation whether this was realized in all patients and whether the study really only included men for whom chemotherapy was not an option, which is a prerequisite for the use of olaparib. This reduces the certainty of the conclusions, so that only hints can be derived from the study.

The results for the outcomes of overall survival and symptomatic skeletal-related events depend on the age of the patients: For patients under 65 years of age, there is a hint of an added benefit of olaparib in overall survival. For older patients, there is no survival advantage, but a hint of minor added benefit in symptomatic skeletal-related events.

Some results for health-related quality of life and side effects differed according to the organs where metastases were present at the start of the study (bone only or also abdomen and other sites). Both advantages and disadvantages of the new medication were shown. However, regardless of age and type of metastases, there were more serious adverse events, treatment discontinuations due to adverse events and, in particular, severe pulmonary embolisms and blood count changes under olaparib.

Overall, there is a hint of minor added benefit of treatment with olaparib in comparison with the ACT for patients under 65 years of age, but a hint of lesser benefit for older patients.

Advantages or disadvantages for pretreated patients unknown

The patients included in the PROpel study had not yet received pretreatment for metastatic disease, so no conclusions about pretreated patients can be drawn based on this study. The manufacturer did not provide any other adequate data for these patients in its dossier. It remains unclear why the manufacturer’s study list did not include a potentially relevant study sponsored by the manufacturer itself (Study 8), which was used as supplementary information for the approval of olaparib, and why no documents on this study were provided.

On the basis of the available information, it is not possible to assess whether the ACT for pretreated patients was implemented in this study, at least for a subpopulation. Thus, the result is: An added benefit of olaparib plus abiraterone plus prednisone or prednisolone in comparison with the ACT is not proven for adults with pretreated mCRPC.

G‑BA decides on the extent of added benefit

The dossier assessment is part of the early benefit assessment according to the Act on the Reform of the Market for Medicinal Products (AMNOG) supervised by the G‑BA. After publication of the dossier assessment, the G-BA conducts a commenting procedure and makes a final decision on the extent of the added benefit.

You can find an overview of the results of IQWiG’s benefit assessment in an English extract. In addition, the website informedhealth.org published by IQWiG provides easily understandable information on this benefit assessment.