Examining the relevant facts and new insights in PARP inhibition Dr Maurizio D’Incalci, MD Chief of Cancer Pharmacology Laboratory and Head of Dept Oncology Mario Megri Institute Milan, Italy ESMO 2018 Munich, Germany

Outline Mode of action (canonical and not canonical) Comparative pharmacokinetic features and preclinical anti-tumour activity Analysis of the QUADRA study

Synthetic lethality Igelhart, JD and Silver DP. N Engl J Med 2009;361(2):189-191.

Inhibition of PARP catalytic activity in vitro assay shows selectivity of PARP inhibitors TNKS1 TNKS2 PARP6 PARP7 PARP8 PARP10 Niraparib 2.8 nM 0.6 nM >1 µM Olaparib 1.4 nM 0.8 nM 33 nM NA 722 nM Rucaparib 0.3 nM 39 nM 201 nM 135 nM 787 nM Talazoparib 1.0 nM 0.4 nM 29 nM 15 nM 6.7 nM 988 nM 588 nM <10 nM 10-100 nM 100 nM-1 µM >1 µM Results from a preclinical in vitro assay compared level of inhibition of PARP family members by various PARP inhibitors PARP inhibitors were evaluated side-by-side in a panel of PARP assays by BPS Bioscience PARP, Poly (ADP-ribose) Polymerase; TNKS1, tankyrase Wang Y, et al. Presented at AACR; April 5–9, 2014: San Diego, CA; TESARO, data on file.

There is more than just PARP inhibition Competitive binding to the NAD+ site Catalytic inhibition (IC50 nM) Cytotoxicity (IC90 µM) PARP-trapping potency (relative to olaparib set as 1) Olaparib 6 4.5 1 Rucaparib 21 3 Niraparib 60 2.3 ~2 Talazoparib 4 0.04 ~100 + potency N-term C-term Znl Znll NLS Znlll WGR * H * Y * E DNA-binding domain automodification domain catalytic domain Murai J, et al. Mol Cancer Ther 2014;13(2):433-443.

Cellular effects of PARP1 transcriptional regulation RNA interference cell death control of cell division inflammation PARP1 angiogenesis DNA repair maintenance of telomeres WNT signalling formation of subnuclear bodies mitochondrial function Weaver, AN et al. Front Oncol 2013 https://doi.org/10.3389/fonc.2013.00290 Swindal AF, et al. Cancers 2013;5(3):943-958; doi:10.3390/cancers5030943

Pharmacokinetic and -dynamic profiles of PARP inhibitors Absorption Distribution Metabolism Elimination F (%) Papp (10-6 cm/s) Vd/F (L) Major enzyme t1/2 (h) Niraparib 731 12-182 1,0741 CE1 48-511 Olaparib NA3 4-84 1675 CYP3A45 11.95 Rucaparib 366 6-87 113-2626 CYP2D66 17-196 Niraparib is characterised by: High tumour penetration – largest volume of distribution No relevant drug-drug interaction Once daily dosing with or without food1 F, bioavailability; Papp, apparent permeability; t1/2, half-life; Vd, volume of distribution; CE, carboxyl esterase; CYP, cytochrome p450 oxidase 1. ZEJULA® Summary of Product Characteristics, Nov 2017; 2. TESARO Inc., Data on File; 3. CHMP Assessment Report: Lynparza (EMA/CHMP/789139/2014). Available at: http://www.ema.europe.eu/docs/en_GB/document_library/EPAR_-_Public_assessment_report/human/003726/WC500180154.pdf. Accessed Jan 2018. 4. Clinical pharmacology and biopharmaceutics review: Lynparza. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/nda/2014/206162Orig1s000ClinPharmR.pdf. Accessed Jan 2018; 5. Lynparza Summary of Product Characteristics, July 2017; 6. Rubraca package leaflet, Dec 2016; 7. Durmus S, et al. Pharm Res 2015;32(1):37-46. 8. Zhang ZY, et al. Oral presentation at ISSX 2015, Oct 18-22, 2015, Orlando, USA.

Concentration (ng/mL) Niraparib demonstrated favourable exposure over olaparib in tumour, plasma, and brain Mice bearing BRCA1mut tumour xenografts treated with niraparib exhibited greater AUCs in samples from tumour, plasma, and brain than those treated with olaparib 10 100 10,000 1,000 100,000 6 4 2 8 12 14 16 18 20 22 24 Time (hours) Plasma concentration Tumour concentration Brain concentration 100,000 100,000 10,000 10,000 Concentration (ng/mL) 1,000 1,000 100 100 LLOQ 10 10 6 4 2 8 10 12 14 16 18 20 22 24 6 4 2 8 10 12 14 16 18 20 22 24 Time (hours) Time (hours) Niraparib 75 mg/kg QD ×5 Olaparib 100 mg/kg QD ×5 Studied in mice bearing BRCA1mut tumour xenografts treated with niraparib exhibited greater AUCs in samples from tumour, plasma, and brain than those treated with olaparib AUC, area under the curve; BRCA, breast cancer gene; BRCA1mut, BRCA1 mutation; Cmax, maximum concentration; LLOQ, lower limit of quantification; PK, pharmacokinetics; QD, once daily Sun K, et al. Poster presented at AACR-NCI-EORTC 2017; Philadelphia, PA, USA, October 26–30, 2017.

QUADRA study design and patient eligibility Study aim: Evaluate the efficacy of niraparib in a broad, late-line recurrent ovarian cancer population Patients (N=463) with histologically diagnosed advanced, relapsed, high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received 3 or more prior chemotherapy Niraparib 300 mg orally once daily, 28-day cycles Endpoint assessment Primary Endpoint ORR by RECIST in HRD-positive patients who have received 3 or 4 lines of previous chemotherapy, platinum-sensitive, and PARPi-naïve ORR, Objective Response Rate; HRD, homologous recombination deficiency Moore KN, et al. ASCO 2018; abstract 5514 (poster presentation).

Patient characteristics Patients enrolled in QUADRA represent a broad, late-line population *2/3 of platinum sensitive patients were not treated with platinum in the line immediately prior to study entry HRDpos (220) 68% platinum resistant or refractory 19% BRCAmut; 48% HRDpos 27% in 6th line or later Plat. sens: platinum sensitive (time from last platinum until next progression ≥ 6 months), including platinum-ineligible; Plat. res.: platinum resistant (time from last platinum until next progression between 28 days and 6 months); Plat. ref.: platinum refractory (progression on or within 28 days from last platinum); Plat. unk.: platinum status unknown BRCA, breast cancer gene; BRCAwt, BRCA wild type; gBRCA, germline BRCA; sBRCA, somatic BRCA; HRD, homologous recombination deficiency; neg, negative; pos, positive; unk, unknown Moore KN, et al. ASCO 2018; abstract 5514 (poster presentation).

QUADRA study met primary endpoint Primary endpoint objective response rate (ORR) was 29% in HRDpos population Results of overall population ORR (CR+PR) 27% (14/51) SD 41% (21/51) DCR (CR+PR+SD) 69% (35/51) Median DOR 9.2 months Median OS 19.0 months Primary endpoint for HRDpos patients p=0.0003; 95% CI 16-44, N=45 DOR, median duration of response; DCR, disease control rate (best overall response); HRDpos, homologous recombination deficiency positive; OS, median overall survival; CR, complete response; PR, partial response; SD: stable disease. Moore KN, et al. ASCO 2018; abstract 5514 (poster presentation).

QUADRA: clinical benefit rate across all patient populations Platinum-sensitive or -ineligible Platinum-resistant or -refractory Plat. sens. = platinum sensitive (time from last platinum until next progression ≥ 6 months), including platinum-ineligible; Plat. res. = platinum resistant (time from last platinum until next progression between 28 days and 6 months); Plat. ref. = platinum refractory (progression on or within 28 days from last platinum); CBR16, clinical benefit rate (CR + PR + SD for at least 16 weeks) BRCAmut, breast cancer gene mutant; BRCAwt, breast cancer gene wild-type; HRDpos, homologous recombination deficiency positive; HRDneg/unk, homologous recombination deficiency negative or unknown; CR, complete response; PR, partial response; SD, stable disease Moore K, et al. Presented at 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL. Poster #241.

QUADRA: OS in all patients treated in 4th line or later Population by Biomarker Status OS (months) BRCAmut (N=63) 26.0 (18.1, NE) HRDpos (N=187) 19.0 (15.2, 24.6) HRDneg or unk (N=232) 16.6 (12.6, 19.0) All 4th or later line (N=456)* 17.2 (14.9, 19.8) Historical CT control Line of Therapy OS (months) 4th Line 8.9 (95% CI 7.8 – 9.9) 5th Line 6.2 (95% CI 5.1 – 7.7) 6th Line 5.0 (95% CI 3.8 – 10.4) *all evaluable patients OS, overall survival; CI, confidence interval; BRCAmut, breast cancer susceptibility gene mutant; CT, chemotherapy; HRD, homologous recombination deficiency; HRDpos, HRD positive; HRDneg, HRD negative; unk, unknown; NE, non-evaluable Hanker LC, et al. Ann Oncol 2012;23(10):2605-2612. Moore K, et al. Presented at 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL. Poster #241; TESARO investor & analyst briefing at ASCO 2018; Jun. 4, 2018. Available at: link

Take home points Not all PARP inhibitors are the same as there are some significant differences in the mode of action Important pharmacokinetic properties might explain the different activity and safety of PARP inhibitors Tissue distribution, half-life, metabolism and tumour penetration differentiate niraparib from other PARP inhibitors QUADRA shows significant anti-tumour activity and survival in late-line ovarian cancer