Update on PARP inhibitors

Ursula Matulonis, M.D.

Chief, Division of Gynecologic OncologyBrock-Wilson Family ChairDana-Farber Cancer Institute

Professor of Medicine Harvard Medical School Boston MA

History of PARP inhibitor development

Audeh et al, Lancet 2010NCT00494442

Single agent olaparib has activity in gBRCAm ovarian cancer

3 Randomized phase 2 studies were started:

• Doxil versus olaparib 200 mg or 400 mg BIDfor recurrent germline + BRCA ovarian cancerResults: no differences in RR or PFS for the 3 groups(Kaye et al, JCO 2012)

• Carboplatin/paclitaxel/olaparib vs Carbo/paclitaxel alone for platinum sensitive recurrent ovarian cancerResults: improved PFS for triplet; best results for BRCA+ cancers(Oza et al, JCO 2015)

• Maintenance olaparib versus placebo in pts with platinum sensitive recurrent ovarian cancerResults: Better PFS for olaparib in ITT (Ledermann et al, NEJM 2012)

History of PARP inhibitors• 2011: Astrazeneca decides to halt development of olaparib

as a maintenance therapy for ovarian cancer• 2012: Study 19 NEJM paper published• 2014: Lancet Oncology paper published showing improved

length of remission benefit of olaparib-treated women with BRCAm+ compared to BRCAwt patients (preplanned retrospective analysis)

2012

2014

History of PARP inhibitors• 2011: Astrazeneca decides to halt development of olaparib as a

maintenance therapy for ovarian cancer• 2012: Study 19 NEJM paper published• 2014: Lancet Oncology paper published showing improved

length of remission benefit of olaparib-treated women with BRCAm+ compared to BRCAwt patients (preplanned retrospective analysis)

• June 2014: US Food and Drug Administration (FDA) Oncologic Drugs Advisory Committee (ODAC) voted 11 to 2 that current evidence from clinical studies does not support an accelerated approval for use of olaparib as a maintenance treatment for women with platinum-sensitive relapsed ovarian cancer who have the germline BRCA (gBRCA) mutation, and who are in complete or partial response to platinum-based chemotherapy.

• December 2014: Olaparib wins FDA approval for ovarian cancer based on single agent data

• 2017: niraparib receives FDA approval for maintenance therapy

PARP Inhibitors: Dose/Schedule and Current Regulatory Approvals1

PARP

Inhibitor

Dosage FDA Approvals

Olaparib(Lynparza)

300 mg twice daily (tablet formation)

1) Treatment of germline BRCAm ovarian cancer in patients who have received ≥3 lines of treatment (December 2014)2) Maintenance in patients with recurrent ovarian cancer1 who are in complete or partial response to platinum-based chemotherapy, regardless of tumor BRCA status or histology (August 2017)

Rucaparib(Rubraca)

600 mg twice daily 1) Treatment of BRCAm (either germline or somatic) ovarian cancer in patients who have received ≥2 lines of treatment (December 2016)2) Maintenance in patients with recurrent ovarian cancer1 who are in complete or partial response to platinum-based chemotherapy, regardless of tumor BRCA status and histology (March 2017)

Niraparib (zejula)

300 mg once per day*

*patients who weigh <77 kg or have baseline platelet counts of <150k should consider using 200 mg starting dose2,3

Maintenance in patients with recurrent ovarian cancer1 who are in complete or partial response to platinum-based chemotherapy, regardless of tumor BRCA status and histology (March 2017)

1. Matulonis UA. 2018.2. Moore et al. Gyn Onc. 2018. .3. Berek et al, Ann of Onc 2018.

3 PARP inhibitor maintenance studies

• NOVA (niraparib = Zejula)• SOLO2 (olaparib = Lynparza)• ARIEL3 (rucaparib = rubraca)• All 3 were phase 3 studies, randomized and

placebo controlled; treatment was started AFTER completion of platinum-based chemotherapy

All 3 studies showed remarkably similar results, and all showed an improvement in how long the cancer stays in remission for after chemotherapy compared to placebo NOVA NEJM 2016

SOLO 2 Lancet Onc 2017ARIEL3 Lancet 2017

Single strand breaks

PARP Enzyme Required to Repair Single Strand DNA Breaks

PARP = poly (ADP ribose) polymerase

PARP

Repair by base excision repair

Normal Cell

Homologous RecombinationRepairs Double Strand DNA Breaks

Double strand breaks

Normal Cell

Repair by Homologous

Recombination

Single strand breaks

PARP

PARP inhibitor

Double strand breaks

gBRCAm Cancer Cell

Cell Death

Increase in double strand breaks

Non functioningBRCA protein and abnormal DNA repair

PARP inhibitors need 2 abnormal genetic events to work

Differences in Metabolism and Drug‒Drug Interactions Exist Among PARP Inhibitors

PARP Inhibitor

CYP Enzymes Used for Metabolism

Drug‒Drug Interactions

Effect on Cell Transporters

Niraparib1 • Carboxylesterases(non-CYP)

• Can induce CYP1A2 (weak)

• No interaction with the major hepatic or renal uptake transporters

• Inhibits BCRP (weak)• Substrate of P-

glycoprotein and BCRP

Olaparib1 • CYP3A4 Reduce dosage if strong or moderate CYP3A inhibitors are co-administered

• Inhibits CYP3A4 and induces CYP2B6

• Inhibits MDR1, BCRP, OATP1B1, OCT1, OCT2, OAT3, MATE1, MATE2-K

• Substrate of P-glycoprotein

Rucaparib1 • CYP2D6 (predominant)

• CYP1A2 and CYP3A4 (lesser extent)

• Reversibly inhibits CYP1A2, CYP2C19, CYP2C9, CYP3Aand induces CYP1A2

• Inhibits MATE1 and MATE2-K, OCT1

• Substrate of P-glycoprotein

1. FDA Prescribing Information..

• Each drug is metabolized differently• Other drugs being taken may influence PARPi levels • Drug-drug interactions can occur based on CYP inhibition or induction • Effect on renal transporter proteins MATE1 and MATE2-K can increase serum

creatinine (exception is niraparib)

Gastrointestinal toxicities include:NauseaVomitingDecreased appetiteDiarrheaConstipationAbdominal painUpset stomachTaste changes

Bone marrow suppression:Drop in RBC, WBC, platelets, and small risk ~1-2% risk of AML and/or MDS*higher risk of grade 3 and 4 thrombocytopenia with niraparib (300 mg dose) but this is mitigated by starting at the 200 mg dose for weight <77kg or platelet count <150

FatigueHypertension, tachycardia, palpitations (niraparib)Liver function test elevations, cholesterol rise (rucaparib)Serum creatinine elevation (olaparib, rucaparib)Pneumonitis, increased risks of infections/infestations (olaparib)

FDA PI for niraparib, olaparib and rucaparib SGO 2018 Berek et al, Ann Onc 2018

PARP inhibitor side effects

Addressing PARP Inhibitor-Associated Adverse Events

• Side effects are generally mild-moderate1

– Common side effects include anemia, fatigue, nausea, and vomiting

– Frequently occur during early stage of treatment and then get better over 4-6 weeks

– Often transient and do not require PARPi discontinuation

• Fatigue requires assessment for other underlying causes2

– Screen for fatigue should occur– Moderate or worse fatigue may require

pharmacologic/nonpharmacologic intervention– Dose modification/interruption may be necessary

Matulonis U, et al. 2015 ASCO Annual Meeting. Abstract 5550.Moore KN, Monk BJ. Oncologist. 2016;21(8):954-963.

Challenge: Price of PARP Inhibitors

Value-Based Benchmark Prices per Month of Ovarian Cancer Treatment, by Population

Drug Name WAC per Month Net Price per Month*

Recurrent BRCA-Mutated PopulationOlaparib $13,679 $12,310

Rucaparib $13,940 $12,546

Maintenance Therapy for Platinum-Sensitive DiseaseOlaparib $13,679 $12,310

Niraparib $14,965 $13,468 Rucaparib $13,940 $12,546

*Assumed 10% discounted price.WAC indicates wholesale acquisition cost.

Adapted from ICER Final Report 2017 accessed from www.icer-review.org

Hopeful outcome: Access a PARP inhibitor

that is affordable

Insurance coverage,household income,pharma support, etc

QUESTIONS?