Multicentre Study of Olaparib Maintenance Monotherapy in Platinum Sensitive Relapsed Non gBRCAm Ovarian Cancer Patients

Maintenance monotherapy with the potent polyadenosine 5'diphosphoribose [Poly (ADP-ribose)] polymerisation (PARP) inhibitor (PARPi) olaparib will significantly prolong progression-free survival (PFS) in platinum sensitive relapsed non-germline breast cancer susceptibility gene (BRCA) mutated ovarian cancer patients who are in complete or partial response following platinum based chemotherapy.

Olaparib is a potent PARPi (PARP-1, -2 and -3) that is being developed as an oral therapy, both as a monotherapy (including maintenance) and for combination with chemotherapy and other anticancer agents. PARP inhibition is a novel approach to targeting tumours with deficiencies in DNA repair mechanisms. PARP enzymes are essential for repairing DNA single strand breaks (SSBs). Inhibiting PARP enzymes leads to the persistence of SSBs, which are then converted to the more serious DNA double strand breaks (DSBs) during the process of DNA replication. During the process of cell division, DSBs can be efficiently repaired in normal cells by homologous recombination (HR) repair. Tumours with HR deficiencies (HRDs), such as ovarian cancers in patients with BRCA1/2 mutations, cannot accurately repair the DNA damage, which may become lethal to cells as it accumulates. In such tumour types, olaparib may offer a potentially efficacious and less toxic cancer treatment compared with currently available chemotherapy regimens.

While multiple randomized controlled trials (RCTs) have demonstrated that platinum sensitive BRCAm patients have profound response to maintenance treatment with PARP inhibitors, PARP inhibitors target cells with homologous recombination deficiency (HRD), of which BRCA mutation is only one type. Consistent with the mechanism of action of PARP inhibition, response has also been seen in multiple RCTs in patients who are platinum sensitive but whose tumours do not harbor BRCA mutations. Presumably these responders have defects in other components of HRR pathways, though currently available diagnostic technology is not adequate to reliably identify the full spectrum of HRR deficiencies. Instead, these data support the hypothesis that platinum sensitivity itself is a clinical selection factor for HRD.

Key Inclusion Criteria:

• Female patients with histologically diagnosed relapsed HGSOC (including primary peritoneal and / or fallopian tube cancer) or high grade endometrioid ovarian cancer
• Documented gBRCA1/2 mutation status
• Patients must have completed at least 2 previous courses of platinum containing therapy
• Patients must have normal organ and bone marrow function measured within 28 days of starting study treatment
• ECOG performance status 0-1 (see Appendix E)
• Patients must have a life expectancy ≥16 weeks
• Postmenopausal or evidence of non-childbearing status for women of childbearing potential: negative urine or serum pregnancy test within 28 days of study treatment and confirmed prior to treatment on day 1
• At least one lesion (measurable and/or non-measurable) that can be accurately assessed at baseline with computed tomography (CT) or magnetic resonance imaging (MRI) and is suitable for repeated assessment OR No evidence of disease following a complete response to chemotherapy
• An appropriately prepared tumour sample from the cancer, of sufficient quantity and quality (as specified in the Central Laboratory Services Manual) must be available for future central testing of tumour genetic status

Exclusion criteria

• Patients receiving any systemic hormonal therapy, chemotherapy or radiotherapy (except for palliative reasons) within 3 weeks prior to start of study treatment
• Any previous treatment with PARP inhibitor, including olaparib
• Patients with a germline BRCA mutation that is predicted to be deleterious or suspected deleterious (known or predicted to be detrimental / lead to loss of function)
• Other malignancy unless curatively treated with no evidence of disease for ≥5 years except: adequately treated non-melanoma skin cancer, curatively treated in situ cancer of the cervix, ductal carcinoma in situ (DCIS), Stage 1, grade 1 endometrial carcinoma.
• Concomitant use of known strong CYP3A inhibitors and strong (or moderate CYP3A inducers
• Persistent toxicities (≥ Grade 2 Common Terminology Criteria for Adverse Event (CTCAE) adverse event) caused by previous cancer therapy, excluding alopecia
• Patients with myelodysplastic syndrome (MDS)/acute myeloid leukaemia (AML) or with features suggestive of MDS/AML
• Patients with symptomatic uncontrolled brain metastases