A Real World Perspective of PARP Inhibitor Use in Gynecological Cancer Patients

Introduction: Over the last few years, targeted therapy has become the mainstay maintenance treatment of patients with ovarian cancer including patients with BRCA1/BRCA2 mutations. Poly ADP ribose polymerase inhibitors (PARPi) are effective in the treatment of patients who are in complete or partial remission. PARPi are known to cause hematological adverse events (AEs), but have not been compared directly to each other. Objective: Primary objective was to compare the incidence of hematological and non-hematological AEs associated with the use of PARPi. Methods: This was a single institution, retrospective study evaluating patients who were treated with PARPi for ovarian cancer from January 2017 to October 2020. Patients were stratified according to which PARP inhibitor they received. Results: Ninety-two patients were included in final analysis. Thirty-one (33.7%) patients received niraparib and 61 (66.3%) patients received olaparib. Median age of patients were 64.3 (range, 33.8 to 92.3) years, 66 (71.7%) were white, and 84 (91.3%) had an ECOG PS of 0/1. Patients in the niraparib group experienced a higher rate of hematologic AEs, with 11 (35.5%), 20 (64.5%), and 18 (58.1%) experiencing neutropenia, anemia, and thrombocytopenia, respectively. Eight (13.1%), 24 (39.3%), and 16 (26.2%) patients in the olaparib group experienced neutropenia, anemia, and thrombocytopenia, respectively. Conclusion: This single institution retrospective study outlines the hematological toxicities observed between two PARPi. Our results suggested that niraparib tended to be associated with a higher risk for hematologic toxicities than olaparib. Anemia was the most common hematologic toxicity which was consistent with what has been widely documented in the literature.

Poly(ADP-ribose) polymerase (PARP) inhibitors for the treatment of ovarian cancer

BACKGROUND

Ovarian cancer is the sixth most common cancer in women world-wide. Epithelial ovarian cancer (EOC) is the most common; three-quarters of women present when disease has spread outside the pelvis (stage III or IV). Treatment consists of a combination of  surgery and platinum-based chemotherapy. Although initial responses to chemotherapy are good, most women with advanced disease will relapse. PARP (poly (ADP-ribose) polymerase) inhibitors (PARPi), are a type of anticancer treatment that works by preventing cancer cells from repairing DNA damage, especially in those with breast cancer susceptibility gene (BRCA) variants. PARPi offer a different mechanism of anticancer treatment from conventional chemotherapy.

OBJECTIVES

To determine the benefits and risks of poly (ADP-ribose) polymerase) inhibitors (PARPi) for the treatment of epithelial ovarian cancer (EOC).

SEARCH METHODS

We identified randomised controlled trials (RCTs) by searching the Cochrane Central Register of Controlled Trials (Central 2020, Issue 10), Cochrane Gynaecological Cancer Group Trial Register, MEDLINE (1990 to October 2020), Embase (1990 to October 2020), ongoing trials on www.controlled-trials.com/rct, www.clinicaltrials.gov, www.cancer.gov/clinicaltrials, the National Research Register (NRR), FDA database and pharmaceutical industry biomedical literature.

SELECTION CRITERIA

We included trials that randomised women with EOC to PARPi with no treatment, or PARPi versus conventional chemotherapy, or PARPi together with conventional chemotherapy versus conventional chemotherapy alone.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology. Two review authors independently assessed whether studies met the inclusion criteria. We contacted investigators for additional data. Outcomes included overall survival (OS), objective response rate (ORR), quality of life (QoL) and rate of adverse events.

MAIN RESULTS

We included 15 studies (6109 participants); four (3070 participants) with newly-diagnosed, advanced EOC and 11 (3039 participants) with recurrent EOC. The studies varied in types of comparisons and evaluated PARPi. Eight studies were judged as at low risk of bias in most of the domains. Quality of life data were generally poorly reported. Below we present six key comparisons.  The majority of participants had BRCA mutations, either in their tumour (sBRCAmut) and/or germline (gBRCAmut), or homologous recombination deficiencies (HRD) in their tumours. Newly diagnosed EOC Overall, four studies evaluated the effect of PARPi in newly-diagnosed, advanced EOC. Two compared PARPi with chemotherapy and chemotherapy alone. OS data were not reported. The combination of PARPi with chemotherapy may have little to no difference in progression-free survival (PFS) (two studies, 1564 participants; hazard ratio (HR) 0.82, 95% confidence interval (CI 0).49 to 1.38; very low-certainty evidence)(no evidence of disease progression at 12 months' 63% with PARPi versus 69% for placebo).  PARPi with chemotherapy likely increases any severe adverse event (SevAE) (grade 3 or higher) slightly (45%) compared with chemotherapy alone (51%) (two studies, 1549 participants, risk ratio (RR) 1.13, 95% CI 1.07 to 1.20; high-certainty evidence). PARPi combined with chemotherapy compared with chemotherapy alone likely results in little to no difference in the QoL (one study; 744 participants, MD 1.56 95% CI -0.42 to 3.54; moderate-certainty evidence).  Two studies compared PARPi monotherapy with placebo as maintenance after first-line chemotherapy in newly diagnosed EOC. PARPi probably results in little to no difference in OS (two studies, 1124 participants; HR 0.81, 95%CI 0.59 to 1.13; moderate-certainty evidence) (alive at 12 months 68% with PARPi versus 62% for placebo). However, PARPi may increase PFS (two studies, 1124 participants; HR 0.42, 95% CI 0.19 to 0.92; low-certainty evidence) (no evidence of disease progression at 12 months' 55% with PARPi versus 24% for placebo). There may be an increase in the risk of experiencing any SevAE (grade 3 or higher) with PARPi (54%) compared with placebo (19%)(two studies, 1118 participants, RR 2.87, 95% CI 1.65 to 4.99; very low-certainty evidence), but the evidence is very uncertain. There is probably a slight reduction in QoL with PARPi, although this may not be clinically significant (one study, 362 participants; MD -3.00, 95%CI -4.48 to -1.52; moderate-certainty evidence).  Recurrent, platinum-sensitive EOC Overall, 10 studies evaluated the effect of PARPi in recurrent platinum-sensitive EOC. Three studies compared PARPi monotherapy with chemotherapy alone. PARPi may result in little to no difference in OS (two studies, 331 participants; HR 0.95, 95%CI 0.62 to 1.47; low-certainty evidence) (percentage alive at 36 months 18% with PARPi versus 17% for placebo). Evidence is very uncertain about the effect of PARPi on PFS (three studies, 739 participants; HR 0.88, 95%CI 0.56 to 1.38; very low-certainty evidence)(no evidence of disease progression at 12 months 26% with PARPi versus 22% for placebo). There may be little to no difference in rates of any SevAE (grade 3 or higher) with PARPi (50%) than chemotherapy alone (47%) (one study, 254 participants; RR 1.06, 95%CI 0.80 to 1.39; low-certainty evidence). Four studies compared PARPi monotherapy as maintenance with placebo. PARPi may result in little to no difference in OS (two studies, 560 participants; HR 0.88, 95%CI 0.65 to 1.20; moderate-certainty evidence)(percentage alive at 36 months 21% with PARPi versus 17% for placebo). However, evidence suggests that PARPi as maintenance therapy results in a large PFS (four studies, 1677 participants; HR 0.34, 95% CI 0.28 to 0.42; high-certainty evidence)(no evidence of disease progression at 12 months 37% with PARPi versus 5.5% for placebo). PARPi maintenance therapy may result in a large increase in any SevAE (51%) (grade 3 or higher) than placebo (19%)(four studies, 1665 participants, RR 2.62, 95%CI 1.85 to 3.72; low-certainty evidence). PARPi compared with chemotherapy may result in little or no change in QoL (one study, 229 participants, MD 1.20, 95%CI -1.75 to 4.16; low-certainty evidence). Recurrent, platinum-resistant EOC Two studies compared PARPi with chemotherapy. The certainty of evidence in both studies was graded as very low. Overall, there was minimal information on the QoL and adverse events.

AUTHORS' CONCLUSIONS

PARPi maintenance treatment after chemotherapy may improve PFS in women with newly-diagnosed and recurrent platinum-sensitive EOC; there may be little to no effect on OS, although OS data are immature. Overall, this is likely at the expense of an increase in SevAE. It is  disappointing that data on quality of life outcomes  are relatively sparse. More research is needed to determine whether PARPi have a role to play in platinum-resistant disease.

Real-world evidence of poly ADP-ribose polymerase inhibitors in the treatment of ovarian cancer: A systematic literature review

OBJECTIVE

The treatment landscape for ovarian cancer has shifted in recent years with the approval of poly ADP-ribose polymerase inhibitors in 2014. Most patients with ovarian cancer have advanced disease at diagnosis. Understanding how treatments for advanced disease work in real-world settings must be assessed to provide care for these patients. Therefore, the objective of this study was to locate and assess real-world studies measuring the safety and effectiveness of poly ADP-ribose polymerase inhibitors and analyze the results.Data sources: A targeted systematic literature review was conducted in April 2020 of PubMed/Medline. Inclusion criteria consisted of observational studies using real-world data of olaparib, rucaparib, or niraparib as an intervention in the treatment of ovarian cancer. In addition, studies needed to assess either clinical effectiveness or safety. Once studies were identified, we aimed to narratively describe the studies' patient population, intervention effectiveness, and/or safety.Data summary: Our systematic review identified six studies assessing the real-world effectiveness and/or safety of poly ADP-ribose polymerase inhibitors, with five assessing olaparib, one assessing poly ADP-ribose polymerase inhibitors as a composite, and none assessing either niraparib or rucaparib. The median progression free survival in the real-world trials for olaparib ranged from 12.7 to 15.6 months. The median overall survival in the real-world trials for olaparib ranged from 30.9 to 35.4 months. Rates of treatment discontinuation due to adverse events for olaparib ranged from 4.4% to 12.5%.

CONCLUSIONS

The identified studies showed slightly higher, but comparable results for median progression free survival, median overall survival, and discontinuation due to adverse events compared to the respective randomized controlled trials.