Association between Olaparib Exposure and Early Toxicity in BRCA-Mutated Ovarian Cancer Patients: Results from a Retrospective Multicenter Study

Age Is a Risk Factor for Olaparib Dose Modification and Discontinuation in Patients With Ovarian Cancer

Background/Aim

Olaparib, a poly (ADP-ribose) polymerase inhibitor, is widely used as maintenance therapy for ovarian cancer. Dose modification, such as dose reduction and treatment interruption, are frequently performed to manage adverse events (AEs) of olaparib. By identifying patients at high risk for dose modification before administration, interventions related to appropriate control of AEs can be implemented. This study aimed to evaluate risk factors of olaparib dose modification and its clinical usefulness.

Patients and Methods

Sixty patients with ovarian cancer who received olaparib were included in this retrospective cohort study. Associations between patients' characteristics and dose modification were evaluated by multivariate logistic regression analysis. We also examined whether risk factors of dose modification were associated with treatment discontinuation due to AEs.

Results

Twenty-five (41.7%) patients required dose modification. Patients who required dose modification were significantly older (p=0.018) and tended to be more underweight (p=0.078) than those who did not require dose modification. In multivariate analysis, increasing age was significantly associated with dose modification (odds ratio=1.056; 95% confidence interval=1.002-1.112; p=0.034). The optimal cutoff of age as a risk factor for dose modification, calculated from receiver operating characteristic curves, was 65.0 years. Patients aged 65.0 years and older were significantly more likely to discontinue olaparib owing to AEs (p=0.0437).

Conclusion

Age is a risk factor of olaparib dose modification due to AEs. Older patients, who frequently require dose modification, are more likely to discontinue olaparib, suggesting that strict management of AEs is particularly necessary in this patient group.

Improving olaparib exposure to optimize adverse effects management

Background

Olaparib is an inhibitor of the human poly-(ADP-ribose)-polymerase enzymes (PARP1/2) needed to repair single-strand DNA breaks. It is used in breast, ovarian, prostate and pancreatic cancer.

Objectives

This work aimed to describe the pharmacokinetics/pharmacodynamics (PK/PD) relationship between olaparib plasma concentrations and common adverse effects (i.e. anaemia and hypercreatininaemia), in a real-life setting, to propose a target concentration for therapeutic drug monitoring.

Methods

Two PK/PD models describing the evolution of haemoglobinaemia and creatininaemia as a function of time were developed, based on data from, respectively, 38 and 37 patients receiving olaparib. The final model estimates were used to calculate the incidence of anaemia and creatinine increase according to plasma trough concentrations for 1000 virtual subjects to define target exposure.

Results

The final models correctly described the temporal evolution of haemoglobinaemia and creatininaemia for all patients. The haemoglobinaemia PK/PD model is inspired by Friberg's model, and the creatininaemia PK/PD model is an indirect response model. Model parameters were in agreement with physiological values and close to literature values for similar models. The mean (population) plasma haemoglobin concentration at treatment initiation, as estimated by the model, was 11.62 g/dL, while creatinine concentration was 71.91 µmol/L. Using simulations, we have identified a target trough concentration of 3500-4000 ng/mL, above which more than 20% of patients would report grade ≥3 anaemia.

Conclusion

Based on real-world data, we were able to properly describe the time course of haemoglobinaemia and plasma creatininaemia during olaparib treatment.

A retrospective analysis of haematological side effects of olaparib in excess-weight and normal BMI patients with ovarian cancer

Background

Olaparib is the first poly(ADP-ribose) polymerase inhibitor approved in Europe for the treatment of platinum-sensitive patients with newly diagnosed or recurrent platinum-sensitive ovarian cancer with a confirmed BRCA mutation or homologous recombination deficiency (HRD). Epidemiological studies have shown an incompatible association between ovarian cancer and obesity, but there have also been scientific reports indicating that obesity, especially severe obesity, increases the risk of ovarian cancer. Olaparib has a wide range of side effects, especially anaemia and neutropenia, which may lead to dose reduction or therapy discontinuation. Therefore, therapeutic drug monitoring (TDM) is recommended. The aim of the study was a retrospective analysis of threshold value of the trough concentration of olaparib (Ctrough) and haematological adverse reactions after olaparib treatment (300 mg/12 h) in excess-weight and normal body mass index (BMI) patients with ovarian cancer.

Materials and methods

The pilot study was conducted on 38 ovarian cancer patients who were divided into two groups: I - normal BMI patients (BMI = 18.5-24.9 kg/m2; n = 14), II - excess-weight patients, i.e. overweight and obese patients (BMI ≥ 25 kg/m2; n = 24). The severity of neutropenia and anaemia was graded according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0). The values of the mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and red blood cell distribution width (RDW) parameters were also taken into account. HPLC-UV method (λ = 254 nm) was applied to measure olaparib plasma concentrations.

Results

There were no statistically significant differences in olaparib Ctrough between the groups - 1602.86 vs. 1567.40 ng/mL (p = 0.9156). However, the overweight and obese patients had slightly higher dose/kg-adjusted olaparib Ctrough - 204.17 vs. 159.32 ng/mL/mg/kg. The incidence of grade 1 anaemia in the groups was as follows: I - 42.86%, II - 41.67%. Grade 2 and 3 anaemia was observed only in group II - 4.17% and 8.33%, respectively. The incidence of neutropenia in the groups of patients was as follows: grade 1: group I - 21.43%, group II - 20.83%; grade 2: group I - 7.14%, group II - 4.17%.

Conclusions

The incidence of haematological adverse reactions to olaparib, such as neutropenia and grade 1 anaemia in the group of overweight and obese patients was the same as in the normal BMI group. The overweight and obese patients were characterised by higher severity of haematological adverse reactions to olaparib and slightly higher dose/kg-adjusted olaparib Ctrough. After one month of treatment with olaparib the overweight and obese patients had significantly lower red blood cells (RBC) and haemoglobin (Hgb) levels than the patients with normal BMI, which may indicate that anaemia develops faster in this group of patients.

Cytochrome P450 inhibitor/inducer treatment patterns among patients in the United States with advanced ovarian cancer who were prescribed or were eligible for poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitors in the first-line maintenance setting

Poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPi) are metabolized either via carboxylesterase (niraparib) or cytochrome P450 (CYP) enzymes (olaparib and rucaparib). Patients with advanced epithelial ovarian cancer (aOC) who receive concomitant medication metabolized by the CYP system may be at risk of drug-drug interactions impacting PARPi efficacy and tolerability. This study investigated CYP inhibitor/inducer treatment patterns in the first-line maintenance (1Lm) setting for patients with aOC. This retrospective cohort study used de-identified databases of US patients with aOC. Eligible patients were aged ≥18 years, diagnosed with aOC between January 2015-March 2021, and received CYP inhibitors/inducers during 1Lm PARPi initiation or the eligibility window (90 days before to 120 days after first-line platinum-based therapy ended [index]). Patients were either prescribed 1Lm PARPi monotherapy (PARPi cohort) or were not prescribed any 1Lm therapy within 120 days post-index (PARPi-eligible cohort). Strong/moderate CYP inhibitors/inducers were defined as area under the plasma concentration-time curve ratio (AUCR) ≥2 or clearance ratio (CL) ≤0.5 (inhibitors), and AUCR ≤0.5 or CL ratio ≥2 (inducers). Of 1411 patients (median age 63), 158 were prescribed PARPis and 1253 were PARPi-eligible. Among the PARPi cohort, 46.2%, 48.7%, and 5.1% were prescribed niraparib, olaparib, and rucaparib, respectively. For patients prescribed olaparib or rucaparib, 42.4% also received strong and/or moderate CYP inhibitors/inducers. This real-world study indicated a considerable proportion of patients received strong and/or moderate CYP inhibitors/inducers and were prescribed PARPis metabolized by the CYP system. Understanding potential impacts of concomitant CYP inhibitors/inducers on PARPi efficacy and safety is warranted.

Safety of bevacizumab and olaparib as frontline maintenance therapy in advanced ovarian cancer: expert review for clinical practice

Olaparib, a poly(ADP-ribose) polymerase inhibitor, in combination with the antiangiogenic agent bevacizumab, is approved as maintenance therapy for patients with newly diagnosed stage III or IV epithelial ovarian cancer who have homologous recombination deficient tumors with a deleterious or suspected deleterious BRCA mutation and/or genomic instability based on the long-lasting survival benefit observed in the PAOLA-1 trial. Despite treatment with olaparib and bevacizumab showing an acceptable safety profile, the rate of discontinuations due to adverse events was relatively high, and toxicity related to this regimen may restrict its clinical use. Proper management of olaparib/bevacizumab-related adverse events is important for the improvement of quality of life and maximization of the efficacy of maintenance therapy. Here, we summarize the safety results of the PAOLA-1 study, focusing on treatment discontinuation reasons and adverse event profiles. We sought to shed light on toxicity monitoring and prevention, providing concise recommendations for the clinical management of the most relevant side effects.

Combination of Osimertinib and Olaparib Therapy to Treat Non-Small Cell Lung Cancer and High-Grade Serous Ovarian Carcinoma: A Case Report

We present the case of a 75-year-old female with simultaneous EGFR-mutated stage IV lung cancer and advanced BRCA2-mutated ovarian cancer, treated with a unique regimen. In this case report, the patient was treated with alternating months of osimertinib and olaparib to control her lung and ovarian cancers, respectively. When both diseases showed progression, the patient underwent a trial of concurrent therapy with both drugs, yet this was discontinued due to patient-reported adverse side effects. Combination targeted drug therapy may be required to treat complex diagnoses such as dual malignancies. However, combination drug therapy consisting of osimertinib and olaparib has not previously been explored. This case report represents the first to demonstrate osimertinib and olaparib combination therapy as a unique treatment regimen for concurrent lung and ovarian cancers. These two drugs can either be given in an alternating way or given together, short-term, with a higher but tolerable toxicity profile.

Development of a simple high-performance liquid chromatography-ultraviolet detection method for olaparib in patients with ovarian cancer

Olaparib is a small-molecule inhibitor of poly(ADP)-ribose polymerase (PARP) used as maintenance therapy for recurrent ovarian cancer and newly diagnosed advanced ovarian cancer after initial chemotherapy. An exposure-toxicity correlation has been reported between the probability of anemia, a common adverse event associated with olaparib, and the steady-state minimum plasma concentration (Cmin) as well as the predicted maximum plasma concentration (Cmax). On the other hand, olaparib exhibits high interpatient variability with regard to the area under the concentration-time curve, Cmax, and Cmin. Therefore, we developed a simple and sensitive assay based on high-performance liquid chromatography with ultraviolet light (HPLC-UV) for the therapeutic drug monitoring of olaparib. The analysis was performed on an octadecylsilyl column with a mobile phase consisting of 0.5% KH2PO4 (pH 4.5) and acetonitrile (71:29, v/v), at a flow rate of 0.8 mL/min. Olaparib and an internal standard (imatinib) were well separated from the co-extracted material, with retention times of 13.6 and 11.5 min, respectively. The calibration curve for olaparib showed linearity over the concentration range of 0.10-10.0 μg/mL (r2 = 0.9998). The intra- and inter- day validation coefficients ranged from 1.79 to 4.13% and 1.37 to 3.55%, respectively. Measurement accuracy ranged from - 6.07 to 3.26%, with a recovery rate of more than 91.06%. The developed method was then applied to evaluate the plasma olaparib concentrations in patients with ovarian cancer. Our findings demonstrate that HPLC-UV is an economical, simple, and sensitive method for clinical application and holds promise for the effective drug monitoring of olaparib during ovarian cancer treatment.

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

Physiologically-based pharmacokinetic modeling for optimal dosage prediction of olaparib when co-administered with CYP3A4 modulators and in patients with hepatic/renal impairment

This study aimed to develop a physiologically-based pharmacokinetic (PBPK) model to predict the maximum plasma concentration (Cmax) and trough concentration (Ctrough) at steady-state of olaparib (OLA) in Caucasian, Japanese and Chinese. Furthermore, the PBPK model was combined with mean and 95% confidence interval to predict optimal dosing regimens of OLA when co-administered with CYP3A4 modulators and administered to patients with hepatic/renal impairment. The dosing regimens were determined based on safety and efficacy PK threshold Cmax (< 12,500 ng/mL) and Ctrough (772-2500 ng/mL). The population PBPK model for OLA was successfully developed and validated, demonstrating good consistency with clinically observed data. The ratios of predicted to observed values for Cmax and Ctrough fell within the range of 0.5 to 2.0. When OLA was co-administered with a strong or moderate CYP3A4 inhibitor, the recommended dosing regimens should be reduced to 100 mg BID and 150 mg BID, respectively. Additionally, the PBPK model also suggested that OLA could be not recommended with a strong or moderate CYP3A4 inducer. For patients with moderate hepatic and renal impairment, the dosing regimens of OLA were recommended to be reduced to 200 mg BID and 150 mg BID, respectively. In cases of severe hepatic and renal impairment, the PBPK model suggested a dosing regimen of 100 mg BID for OLA. Overall, this present PBPK model can determine the optimal dosing regimens for various clinical scenarios involving OLA.

Managing Adverse Effects Associated With Poly (ADP-ribose) Polymerase Inhibitors in Ovarian Cancer: A Synthesis of Clinical Trial and Real-World Data

The use of poly (ADP-ribose) polymerase (PARP) inhibitor therapy is standard care in the management of patients with various malignancies including ovarian, breast, prostate, and pancreatic cancers. PARP inhibitors have been approved in different settings for patients with specific hereditary pathogenic variants, most notably homologous recombination repair pathways such as BRCA1 and BRCA2 genes. The vast experience with PARP inhibitors (olaparib, niraparib, rucaparib) has been in the management of epithelial ovarian cancer. There have not been any head-to-head comparisons of PARP inhibitors in randomized trials, and we can only perform cross-comparison on the basis of the reported literature. The three approved PARP inhibitors share several common adverse effects because of a class effect including nausea, fatigue, and anemia, but there are notable differences likely because of variations in their poly-pharmacology and off-target effects. Finally, patients included in clinical trials are often younger with a good performance status and less comorbidities than the real-world population, and hence, the potential benefits and adverse effects may not be superimposable. In this review, we describe these differences and discuss strategies to mitigate and manage adverse side effects effectively.

SNRPD1 conveys prognostic value on breast cancer survival and is required for anthracycline sensitivity

BACKGROUND

Cancers harboring spliceosome mutations are highly sensitive to additional perturbations on the spliceosome that leads to the development of onco-therapeutics targeting the spliceosome and opens novel opportunities for managing aggressive tumors lacking effective treatment options such as triple negative breast cancers. Being the core spliceosome associated proteins, SNRPD1 and SNRPE have been both proposed as therapeutic targets for breast cancer management. Yet, their differences regarding their prognostic and therapeutic use as well as roles during carcinogenesis are largely unreported.

METHODS

We conducted in silico analysis at gene expression and genetic levels to differentiate the clinical relevance of SNRPD1 and SNRPE, and explored their differential functionalities and molecular mechanistic associations with cancer in vitro.

RESULTS

We showed that high SNRPD1 gene expression was prognostic of poor breast cancer survival whereas SNRPE was not. The SNRPD1 expression quantitative trait loci, rs6733100, was found independently prognostic of breast cancer survival using TCGA data. Silencing either SNRPD1 or SNRPE independently suppressed the growth of breast cancer cells, but decreased migration was only observed in SNRPD1-silenced cells. Knocking down SNRPD1 but not SNRPE triggers doxorubicin resistance in triple negative breast cancer cells. Gene enrichment and network analyses revealed the dynamic regulatory role of SNRPD1 on cell cycle and genome stability, and the preventive role of SNRPE against cancer stemness that may neutralize its promotive role on cancer cell proliferation.

CONCLUSION

Our results differentiated the functionalities of SNRPD1 and SNRPE at both prognostic and therapeutic levels, and preliminarily explained the driving mechanism that requires additional explorations and validations.

Exposure-Response Analyses of Olaparib in Real-Life Patients with Ovarian Cancer

BACKGROUND

Olaparib is given in a fixed dose of twice-daily 300 mg in patients who are diagnosed with ovarian cancer, breast cancer, prostate cancer or pancreas cancer and has a high interpatient variability in pharmacokinetic exposure. The objective of this study was to investigate whether pharmacokinetic exposure of olaparib is related to efficacy and safety in a real-life patient' cohort.

METHODS

A longitudinal observational study was conducted in patients who received olaparib for metastatic ovarian cancer of whom pharmacokinetic samples were collected. A Kaplan-Meier analyses was used to explore the relationship between olaparib exposure, measured as (calculated) minimum plasma concentrations (C_min), and efficacy, Univariate and multivariate cox-regression analyses were performed. Also, the C_min of patients who experienced toxicity was compared with patients who did not experience any toxicity.

RESULTS

Thirty-five patients were included in the exposure-efficacy analyses, with a median olaparib C_min of 1514 ng/mL. There was no statistical significant difference in PFS of patients below and above the median C_min concentration of olaparib, with a hazard ratio of 1.06 (95% confidence interval: 0.46-2.45, p = 0.9)). For seven patients pharmacokinetic samples were available before toxicity occurred, these patients had a higher C_min of olaparib in comparison with patients who had not experienced any toxicity (n = 33), but it was not statistically significant (p = 0.069).

CONCLUSIONS

Our study shows that exposure of olaparib is not related to PFS. This suggests that the approved dose of olaparib yields sufficient target inhibition in the majority of patients.

Bioanalytical Methods for Poly(ADP-Ribose) Polymerase Inhibitor Quantification: A Review for Therapeutic Drug Monitoring

BACKGROUND

Therapeutic drug monitoring (TDM) of poly(ADP-ribose) polymerase inhibitors (PARPis) is an exploratory practice aimed at improving the quality of treatment through personalized therapy. Currently, there are 4 European Medicines Agency-approved and US Food and Drug Administration-approved PARPis available clinically whose quantification requires validated analytical methods: olaparib, niraparib, rucaparib, and talazoparib. The purpose of this literature review was to highlight the pharmacological features of PARPis that could support their TDM practice and provide a detailed discussion of the available liquid chromatography coupled with tandem mass spectrometry methods for their quantification.

METHODS

Using several Medical Subject Heading terms, the literature was searched using several research engines, including SciFinder, Web of Science, Google Scholar, and PubMed, to find articles published before August 2022.

RESULTS

Exposure-efficacy and exposure-safety profiles, drug-drug interactions, and hepatic/renal impairment of PARPis provide the potential rationale to monitor their concentrations through TDM. Several bioanalytical methods for their quantification have been reported and compared, and a great deal of heterogeneity has been found among methods, regarding both their analytical and regulatory aspects.

CONCLUSIONS

In addition to reducing toxicity and increasing the efficacy of PARPis therapy, TDM could be beneficial to thoroughly investigate the exposure-response relationships of PARPis and to establish pharmacokinetic thresholds for clinical decisions. Based on the comparison of published bioanalytical methods, their transferability and validation both play a key role in method selection. For future use in clinical TDM, we anticipate that bioanalytical methods should address every analytical need more thoroughly and should be validated with standardized guidelines.

Pharmacokinetics and Pharmacodynamics of PARP Inhibitors in Oncology

Olaparib, niraparib, rucaparib, and talazoparib are poly (ADP-ribose) polymerase (PARP) inhibitors approved for the treatment of ovarian, breast, pancreatic, and/or prostate cancer. Poly (ADP-ribose) polymerase inhibitors are potent inhibitors of the PARP enzymes with comparable half-maximal inhibitory concentrations in the nanomolar range. Olaparib and rucaparib are orally dosed twice a day, extensively metabolized by cytochrome P450 enzymes, and inhibitors of several enzymes and drug transporters with a high risk for drug-drug interactions. Niraparib and talazoparib are orally dosed once a day with a lower risk for niraparib and a minimal risk for talazoparib to cause drug-drug interactions. All four PARP inhibitors show moderate-to-high interindividual variability in plasma exposure. Higher exposure is associated with an increase in toxicity, mostly hematological toxicity. For talazoparib, exposure-efficacy relationships have been described, but for olaparib, niraparib, and rucaparib this relationship remains inconclusive. Further studies are required to investigate exposure-response relationships to improve dosing of PARP inhibitors, in which therapeutic drug monitoring could play an important role. In this review, we give an overview of the pharmacokinetic properties of the four PARP inhibitors, including considerations for patients with renal dysfunction or hepatic impairment, the effect of food, and drug-drug interactions. Furthermore, we focus on the pharmacodynamics and summarize the available exposure-efficacy and exposure-toxicity relationships.

Development of Chitosan-Coated PLGA-Based Nanoparticles for Improved Oral Olaparib Delivery: In Vitro Characterization, and In Vivo Pharmacokinetic Studies

Olaparib (OLP) is an orally active poly (ADP-ribose) polymerase enzyme inhibitor, approved for treatment for the metastatic stage of prostate, pancreatic, breast and ovarian cancer. Due to its low bioavailability, an increase in dose and frequency is required to achieve therapeutic benefits, which also results in associated toxicity in patients. In the current study, OLP-loaded poly (d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) (OLP-PLGA NPs) and a coating of OLP-PLGA NPs with chitosan (CS) (OLP-CS-PLGA NPs) were prepared successfully in order to improve the dissolution rate and bioavailability. The developed OLP-PLGA NPs were evaluated for hydrodynamic particle size (392 ± 5.3 nm), PDI (0.360 ± 0.03), ZP (−26.9 ± 2.1 mV), EE (71.39 ± 5.5%) and DL (14.86 ± 1.4%), and OLP-CS-PLGA NPs, hydrodynamic particle size (622 ± 9.5 nm), PDI (0.321 ± 0.02), ZP (+36.0 ± 1.7 mV), EE (84.78 ± 6.3%) and DL (11.05 ± 2.6%). The in vitro release profile of both developed NPs showed a sustained release pattern. Moreover, the pharmacokinetics results exhibited a 2.0- and 4.75-fold increase in the bioavailability of OLP-PLGA NPs and OLP-CS-PLGA NPs, respectively, compared to normal OLP suspension. The results revealed that OLP-CS-PLGA NPs could be an effective approach to sustaining and improving the bioavailability of OLP.