Understanding Myelofibrosis: Key Questions and JAK Inhibitors

1. Key Questions in Myelofibrosis Bart Scott, MD Associate Member, FHCRC Associate Professor, UWMC

2. Questions • Role of JAKi? • What is the optimal time to perform HCT? • Does fibrosis persist after HCT?

3. Questions • Role of JAKi?

4. Origin of MPN MF: Dr. Gustav Heuck 1879 Two cases of leukemia with peculiar blood and bone marrow findings, respectively PV: Dr. Louis Henri Vaquez 1892 On a special form of cyanosis accompanied by excessive and persistent erythrocytosis Dr. Osler coins “Vaquez’s disease” in 1903 chronic cyanosis with polycythemia and enlarged spleen ET: Drs. Emil Epstein and Alfred Goedel 1934 Hemorrhagic thrombocythemia with a cascular, sclerotic spleen Closely interrelated disorders… variable manifestations of proliferative activity… perhaps due to a hitherto uncharacterized stimulus. Dameshek et al. Blood. 1951;6:372-375 Levine and Gilliland Blood. 2008;112:2190-2198

5. STAT, signal transducer and activator of transcription MPN Etiology: Role of JAK2 Mutation Single point mutation G to T valine to phenylalinine JAK1 pro-inflammatory cytokines (IL-1, IL-6, TNFα) JAK2 hematopoietic growth factors (Epo, GM-CSF, tepo, Il-3, Il-5) JAK3 mediates immune function (SCID) TYK-2 cytokine signaling (IL-12) Transactivation Goldman J. N Engl J Med. 2005;352:1744-1746 Shuai K, Liu B. Nat Rev Immunol. 2003;3(11):900-911.

6. MPL515 exon 10 5% 5% 95-97% JAK2V617F exon 14 60-65% JAK2V617F exon 14 60-65% JAK2V617F exon 14 PV ET MF OTHER MUTATIONS Genetic/Host Interaction TET2 15% ASXL1 32% EZH2 13% RB 19% IDH1, IDH2 2% SRFS2 3% JAK2 EXON 12 2-4% ? JAK2R564Q Familial ET CALR exon 9 Type1: 52 BP deletion Type2: 5 BP insertion 20-25% 20-25% concurrent Genetic Host Genetic Host Pardanani et al. Blood. 2008;111:2785-2789 Vainchenker et al. Blood 2011;118:1723-1735 Vannucchi et al. Leukemia 2013;27:1861-1869 Nangalia J et al. N Engl J Med 2013;369:2391-2405 Pardanani et al. Blood. 2006;108:3472-3476 Scott et al. N Engl J Med. 2007;356:459-468 Kralovics et al. N Engl J Med. 2005;352:1779-1790 Heterozygous Klampfl T et al. N Engl J Med 2013;369:2379-2390

7. Activation of JAK-STAT Pathway O’Sullivan et al. Mol Cell Endocrinol 2017;451:71-79 Elf et al. Blood. 2018;131:782-786

8. MF Diagnostic Criteria ¥ ‡ ∫ § ¥ failure of Fe to to increase Hgb in setting of a low ferritin ‡ absence of BCR-ABL1. ∫absence of erythroid and granulocytic dysplasia †In the absence of any of the 3 major clonal mutations, the search for the most frequent accompanying mutations (eg, ASXL1, EZH2, TET2, IDH1/IDH2, SRSF2, SF3B1) are of help in determining the clonal nature of the disease. § infection, autoimmune, chronic inflammatory, hairy cell leukemia or other lymphoid neoplasm, met malignancy, or toxic chronic myelopathies 1 Arber, et al. Blood. 2016;127(20):2391-24052Barosi G, et al. Leukemia. 2008;22(2):437-438.

9. JAK Inhibitors PAC Inhibits JAK2, FLT3, IRAK1, and CSF1R RUX Pyrrolopyrimidine Macrocyclic MMB FED Crosses CNS Structurally similar to thiamine Inhibits JAK1, JAK2, ACVR1 1M929I mutation gatekeeper mutation Jak2 inhibitor Anilinopyrimidine derivatives 1Deshpande et al. Leukemia 2012;26:708-715 Deunas-Perez Ther Adv Hematol 2015;6:186-201

10. COMFORT-I: Study Design • N=309 • PMF, PPV-MF, or PET-MF • ≥ 18 years of Age • Intermediate-2 or High-Risk (IPSS) • Plat ≥ 100K • Palpable spleen ≥ 5 cm • PB < 10% • ECOG PS ≤ 3 • Refractory or intolerant to or not candidates for available therapy • Locations: USA, Canada, Australia Ruxolitinib n=15515 mg* or 20 mg† po BID *Baseline platelets 100,000-200,000/μL †Baseline platelets >200,000/μL R Placebo po BID n=154 1:1 Verstovsek et al. N Engl J Med. 2012;366:799-807

11. COMFORT-I: Results SVR at 24 weeks TSS at 24 weeks Placebo (n=153) Ruxolitinib (n=155) Placebo (n=145) Ruxolitinib (n=145) 41.9% 0.7% 5.3% 45.9% OR 15.3 (6.9-33.7), P<0.0001 OR 134.4 (18-1004.9), P<0.0001 Verstovsek et al. N Engl J Med. 2012;366:799-807

12. COMFORT-I: SafetyWorst hematology laboratory abnormalities* Ruxolitinib (n=155) Placebo (n=151) Hematologic adverse reactions rarely led to treatment discontinuation (percentages below are from both phase 3 studies) anemia (0.3%), thrombocytopenia (0.7%), neutropenia (1.0%†) Management of hematologic abnormalities • Thrombocytopenia: Generally reversible; usually managed by reducing the dose or temporarily withholding Jakafi; if clinically indicated, platelet transfusions may be administered • Anemia: Some patients may require blood transfusions; dose modifications may also be considered • Neutropenia (ANC <0.5 x 109/L): Generally reversible; managed by temporarily withholding Jakafi *Presented values are worst Grade values regardless of baseline (National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0) †Includes patients who had a dose reduction Verstovsek et al. N Engl J Med. 2012;366:799-807 Talpaz et al. Jnl Hem and Onc. 013;6:81-91 Phase 2 study in patients with MF plat 50-100

13. COMFORT-I: SafetyObserved non-hematologic adverse reactions Ruxolitinib (n=155) Placebo (n=151) Black Box warning MTB, non melanoma skin cancer, PML, HBV Verstovsek et al. N Engl J Med. 2012;366:799-807

14. COMFORT-II: Study Design • N=219 • PMF, PPV-MF, or PET-MF • ≥ 18 years of Age • Intermediate-2 or High-Risk (IPSS) • Plat ≥ 100K • Palpable spleen ≥ 5 cm • PB < 10% • ECOG PS ≤ 3 • Locations:Austria, Belgium, France, Germany, Italy, Netherlands, Spain, Sweden, UK Ruxolitinib15 mg* or 20 mg† po BID *Baseline platelets 100,000-200,000/μL †Baseline platelets >200,000/μL R Best Available TherapyHydroxyurea (47%) and glucocorticoids (16%) 2:1 Harrison et al. N Engl J Med. 2012;366:787-798 Vannuchi et al. Haematologica 2018;

15. COMFORT-II: Primary EndpointRuxolitinib provided significant reductions in spleen volume Results at 48 weeks • Both COMFORT-I and COMFORT-II demonstrated efficacy for Ruxolitinib with SVR P < 0.0001 Ruxolitinib Harrison et al. N Engl J Med. 2012;366:787-798

16. Overall Survival COMFORT 1 COMFORT 2 62% crossover 45 wks 72% crossover 41 wks Mascarenhas and Hoffman Blood 2013;121:4834-4837 Cervantes et. al. Blood 2013;122:4047-4053

17. Overall Survival in the COMFORT Trials BAT, best available therapy Rank Preserving Structural Failure Time Model • Verstovsek S, et al. N Engl J Med. 2012;366:799-8072. • Verstovsek S, et al. Haematologica 2015;100(4):479-88. • Harrison C, et al. N Engl J Med. 2012;366:787-798. • Cervantes F, et al. Blood 2013;122(25):4047-53. • Verstovsek S. et al. 21st Congress of the European Hematology Association Copenhagen, Denmark, June 9−12, 2016, Abstract S452. • Harrison CN, et al. Blood. 2015;126(23):59.

18. Figure 2 JAKi prior to HCT Group A n=23: SVR 50% or > Group B n=31: Stable Group C n=15: increase in blasts 10-19%, intolerance to Rx, TFN dep anemia Group D n=18: progression with increase in spleen size Group E n=13: Leukemic Transformation Biology of Blood and Marrow Transplantation 2016 22, 432-440DOI: (10.1016/j.bbmt.2015.10.005) Shanavas et al. Biol Blood Marrow Trans. 2016;22:432-440

19. Questions • Role of JAKi? • Rux-SVR, improve TSS, response associated with improved post-HCT OS • Fed-Rux resistance or intolerance • Phase 3B trial Feb 2019 (Fed 400 vs. placebo in Rux failures/intolerance) • MMB-Anemia, plans to develop for this indication • PAC-Plat < 100K • PAC 203 begins accrual 6/17 (100 vs. 100 BID vs. 200 BID) • PERSIST 3 planned for August, 2019

20. Questions • What is the optimal time to perform HCT? • Prognostic Models • Implication of HMR • JAKi failure

21. HCT vs. Non-HCT in Primary MF Age <65 years Matched Donors 188 HCT; 255 DIPSS RIC 91, MAC 97 No JAKi RR 5.6 (1.7-19), p=0.0051 HCT 22, DIPSS 125 RR 1.6 (0.79-3.2), p=.19 HCT 38, DIPSS 75 RR 0.55 Int-2 (0.36-.83), p=0.005 HCT 84, DIPSS 52 RR 0.37 (0.21-.66), p=0.0007 HCT 44, DIPSS 3 Kröger, Scott et al. Blood. 2015;125:3347-3350

22. HCT vs. non-HCT Non HCT patients: 14 US Academic Centers-MPN Consortium (JAKi era) HCT patients: CIBMTR Time zero was time of referral for the non HCT arm and the time of HCT for the HCT arm. DIPSS risk categories 1377 non HCT (median age 61) 551 HCT (median age 55) patients HCT>nonHCT p<0.0001 No survival advantage with HCT HCT>nonHCT p<0.0001 Ballen, Scott et al. data unpublished

23. MIPSS 70+ in PMF *HMR=ASXL1, EZH2, SRSF2, IDH1/2 Unfavorable karyotype-abnormal karyotype other than normal karyotype or sole abnormalities of 20q2, 13q2, +9, chromosome 1 translocation/duplication, -Y, or sex chromosome abnormality other than -Y Low Risk 0-2 Int 3 High 4-6 Very High ≥ 7 805 PMF patients—training and validation set; analysis in transplant age and entire cohort Guglielmelli Jnl Clin Oncol 2018;36:310-318

24. MIPSS 70+ Predicts HCT Outcomes Flu 125 mg/m2 Mel 100-140 mg/m2 Med Age 59 (42-72) PBSC 97% MRD/MUD 45%/42% Ali et al. Blood Adv. 2019;3:83-95

25. HMR Predicts TTF and OS following JAKi *HMR=ASXL1, EZH2, SRSF2, IDH1/2 77 patients Rx with Rux 23 patients Rx with MMB Spiegel et al. Blood Adv. 2017;1:1729-1738 Patel et a. Blood. 2015;126:790-797

26. Survival after Rux Failure 6 mosvs. 16 mos ASXL1=15 TET2=4 EZH2=2 DNMT3A/MPL/IDH1/IDH2=1 107 patients RX Rux (2007-2016) 86 patients d/c Rux (30 due to death) 56 patients included in analysis 42 with mutation profile at baseline and F/U Med Survival 14 months (95% CI 10-18) ASXL1+EZH2=1 ASXL1+TET2=1 ASXL1+TET2+JAK2=1 Newberry et al. Blood. 2017;130:1125-1131

27. Questions • What is the optimal time to perform HCT? • Int-High risk disease by DIPSS • HMR mutation • JAKi Failure (plat < 100K or CE)

28. Questions • Does fibrosis persist after HCT?

29. Disease Resolution pre post Reticulin (x300) pre 3 ms 1year T1 Spin Echo (coronal) T1 Spin Echo (transverse) Sale et al. Biol Blood Marrow Trans. 2006;12:1285-1294 STIR Image

30. Osteosclerosis (H&E; x250) Grade 4 Pre-Transplant Post-Transplant (1 year) Sale et al. Biol Blood Marrow Trans. 2006;12:1285-1294

31. Questions • Does fibrosis persist after HCT? • Fibrosis is not the cancer • Mol mutations should be absent • Cyto should be normal