1 / 34

Genetics and targeted therapy of MPNs

Genetics and targeted therapy of MPNs . Raajit Rampal M.D. Ph.D. Leukemia Service Memorial Sloan-Kettering Cancer Center. Scientific Questions/Advances. Are mutations which activate JAK2 a hallmark of all MPN patients? What do mutations which occur in concert with JAK2/MPL mutations do?

gibson
Download Presentation

Genetics and targeted therapy of MPNs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Genetics and targeted therapy of MPNs Raajit Rampal M.D. Ph.D. Leukemia Service Memorial Sloan-Kettering Cancer Center

  2. Scientific Questions/Advances • Are mutations which activate JAK2 a hallmark of all MPN patients? • What do mutations which occur in concert with JAK2/MPL mutations do? • What have we learned about JAK2 inhibitors? • What novel therapies are of potential benefit for MPN patients?

  3. JAK2V617F mutations in myeloid malignancies • Prevalence of JAK2V617F : • - PV: 95% • - ET: 45-50% • - MF: 45-50% • - CMML: 5% • - MDS: RARS-T (>50%) • - AML: 2% James et al. Nature 2005 Levine et al. Cancer Cell 2005 Baxter et al. Lancet 2005 Kralovicset al. NEJM 2005 Zhao et al. JBC 2005

  4. JAK2V617F negative MPN • JAK2V617F-negative PV • JAK2exon 12 mutations • loss of function mutations in LNK, negative regulator of JAK2 (Oh et al Blood 2010) • JAK2V617F-negative ET/PMF • MPL mutations in 10% • LNK mutations in <5% • Somatic mutations had not been identified in 30-40% of MPN patients

  5. Identification of CALR Mutations in JAK2 wildtype MPN Klampfl et al NEJM 2013 Nangalia et al NEJM 2013 • CALR Mutations exclusive of JAK2/MPL mutations • Seen exclusively in ET/MF • Small set (<10%) of ET/MF patients JAK2/MPL/CALR-negative->unknown mutant disease allele

  6. Gene expression – can we measure gene expression and learn something about pathogenesis of MPN? • Determine if there is a common genetic signature associated with MPN or with JAK2V617F mutations • Identify genes which segregate with clinical phenotype • Identify candidate genes in JAK2/MPL/CALR-negative MPN Ben Ebert/Todd Golub

  7. Gene Expression Profiling of MPN Samples distinguishes MPN patients from controls but does not distinguish based on disease or JAK2 status PV PMF ET Homozygous Heterozygous JAK2 negative Control

  8. JAK2 shRNA Is there a JAK2 signature in heterozygous/WT MPN patients? CONTROL JAK2 shRNA in HEL cells to generate JAK2 signature Similar data with JAK inhibitor

  9. JAK2 shRNA signature in MPN and control samples HOMOZYGOUS WT HETEROZYGOUS CONTROL PV MMM ET MMM ET MMM Seen in all MPN patients, not in controls JAK2 is activated in all MPN patients regardless of specific mutation

  10. JAK2 Signature Enriched in CALR-mutant MPN Patients Homozygous vs Normal UP signature JAK2 shRNA down expression signature 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Enrichment Score (ES) Enrichment Score (ES) Normal CALR mutant FDR qvalue= 0.012 Normal CALR mutant FDR qvalue= 0.321 P-value= 0.035 • Consistent with activated JAK2-signaling in CALR-mutant patients

  11. Gene Expression Signature of CALR Mutation • CALR Signature is Enriched in JAK2-mutant MPN patients • Consistent with JAK2 and CALR mutations having same role in MPN pathogenesis – all leads to JAK2 activation

  12. Cooperating Mutations in MPN Patients • Recent studies have identified somatic disease alleles which occur in concert with JAK2/MPL mutations • TET2 loss of function mutations in 10% of MPN patients • ASXL1 mutations in 8-10% of MPN patients • IDH1/2 mutations in 3-5% of MPN patients • EZH2 mutations in 10-15% of patients • Same mutations are seen in MDS and AML patients->they do not explain the PV/ET/MF concondrum • In some cases (TET2, IDH1/2) these mutations occur most commonly at progression to AML • Limited functional data suggest these mutations affect the epigenetic state of MPN cells->affect the way DNA is packaged and which parts of it are used in MPN cells

  13. Leukemic Transformation of MPN • Patients with PV, ET, and PMF are at high risk for transformation to AML • associated with a dismal prognosis • Genetic/Epigenetic events which contribute to leukemic transformation are not known • Approximately 50% of JAK2+ MPN patients transform to a JAK2-negative MPN* *Campbell et al. Blood 2006 Theocarides et al. Blood 2007

  14. Mutational Studies in post-MPN AML No mutations found in c-KIT, EZH2, or WT-1 Denotes frequently mutated in de novo AML Splicesome mutations

  15. Model of MPN Pathogenesis JAK2 rs10974944 Other alleles EZH2, TET2, ASXL1 TET2, IKZF, IDH1/2 Other Alleles • Mutations which activate JAK2 are the most common lesion->best therapeutic target • Possible other mutations affect response to JAK inhibitors AML

  16. JAK Inhibitors in Current Clinical Development • Although structurally divergent, these inhibitors are all Type I (ATP competitive) JAK Inhibitors Courtesy of PriyaKoppikar

  17. Resistance to JAK inhibitors in the treatment of MPNs Phase II/III clinical trials with INCB18424 and other JAK inhibitors • Improvement in splenomegaly, constitutional symptoms, reduced progression to leukemia, survival benefit. • No decrease in allele burden in the majority of MPN patients • May be due, at least in part to presence of other (disease-initiating) alleles JAK2-driven preclinical models argue other factors contribute • JAK2V617F knockin model: Disease initiating cells are resistant to JAK2 inhibitor treatment (Mullally et al. 2010) MPN mutant clone persists in the presence of chronic JAK2 kinase inhibition We have not identified second-site mutations in patients treated with INCB18424 The lack of an initial response argues for inherent insensitivity to JAK inhibitors: persistence • Reactivation of JAK2/JAK-STAT signaling • Activation of a redundant/collateral pathway

  18. JAK-STAT signaling in naïve MPN cells P P P P P P P JAK2 JAK2 MAPK RAS PI3K STAT STAT STAT AKT Nucleus

  19. JAK inhibitors block homodimeric JAK2 activation and downstream signaling in naïve cells JAK2 JAK2 MAPK RAS PI3K STAT AKT Nucleus

  20. JAK-STAT Signaling is Intact in Patients Treated with Ruxolitinib

  21. JAK inhibitors cannot inhibit heterodimeric JAK2 activation and downstream signaling in persistent cells P P P P P P P JAK2 JAK1/ TYK2 MAPK RAS PI3K STAT STAT STAT AKT Nucleus

  22. pJAK2 Associates with JAK1 and TYK2 in MPN Patients treated with Ruxolitinib, but Not in Inhibitor Naïve Patients • Do persistent cells remain JAK2 dependent? • Can persistence be targeted with agents which degrade JAK2 or block JAK2 transactivation?

  23. Persistent Cells are JAK2 dependent SET-2 SET-2 INPer ScrshJ2 81 shJ2 1 Scr shJ2 81 shJ2 1 pJAK2 JAK2 pSTAT3 STAT3 pSTAT5 STAT5 • Loss of JAK2 inhibits growth and signaling in persistent cells Tubulin

  24. Can we improve our ability to target JAK2 • Can we develop better therapies which improve the therapeutic window and target the malignant cell? • - additional therapies • - alternate dosing strategies for JAK2 inhibitors • Can novel compounds be used in a synergistic manner to inhibit JAK2 dependent proliferation? • HSP90 inhibition PU-H71 (HSP90 Inhibitor SachieMarubyashi, PriyaKoppikar

  25. Options: Click-Drag image to reposition | View smaller image | Expand to full image width | Reset image JAK2 is an HSP90 Client and is Degraded by the Purine Scaffold HSP90 Inhibitor PU-H71 JAK2V617F PU-H71 nM JAK2V617F pJAK2 JAK2 pSTAT3 STAT3 pSTAT5 STAT5 pMAPK MAPK HSP90 Raf1 Actin • Similar results with W515L cells: JAK2 is an HSP90 client Marubayashiet al.JCI, 2010

  26. PU-H71 Demonstrates Efficacy in vivo in JAK2V617F and MPLW515L Transplant Models Survival Spleen weights

  27. HSP90 Inhibition Degrades JAK2/Inhibits JAK-STAT signaling in 1° MPN Samples

  28. AUY922 (MSKCC IRB 12-076) • Drug: AUY922 (HSP90 inhibitor) • Study Design: Phase II single-arm • Endpoint: Efficacy of AUY922 assessed by IWG criteria • Patient Population/Eligibility: -PMF -Post-PV/ET MF -Refractory PV/ET (HU, phlebotomy, anagrelide)

  29. CombinationTreatment with JAK and HSP90 Inhibitor Shows Improved Efficacy Compared to Either Therapy Alone p=0.03 p=0.02 p=0.05 p=0.05 p=0.057 p=0.057

  30. CombinationTreatment with JAK and HSP90 Inhibitor Shows Improved Efficacy Compared to Either Therapy Alone Veh INC30 INC90 PU+INC30 pJAK2 JAK2 pSTAT3 STAT3 pMAPK MAPK Actin

  31. Reduced Reticulin Fibrosis with Combination Therapy INC30 with PU Vehicle INC90

  32. PU-H71 + Ruxolitinib Clinical Trial • Drugs: PU-H71, Ruxolitinib • Study Design: Phase I • Endpoint: Efficacy assessed by IWG criteria • Patient Population/Eligibility: -PMF on Ruxolitinib with persistent disease -Post-PV/ET MF on Ruxolitinib with persistent disease

  33. Summary • Mutations which activate JAK-STAT signaling are seen in almost all MPN patients->but there are additional genetic lesions seen in MPN patients which contribute to stem cell survival • Additional novel therapeutic approaches targeted at JAK2 and at other oncogenic signaling pathways might offer benefit alone or in conjunction with JAK2 inhibitors • Genetic studies of myeloid malignancies will likely identify novel mutations with pathogenetic and therapeutic relevance

  34. Acknowledgements • Levine Lab • PriyaKoppikar • NehaBhagwat • OutiKilpivaara • Jay Patel • Franck Rappaport • Alan Shih • Olga Guryanova • Lindsay Saunders • RiaKleppe • Todd Hricik • Sophie McKenney • MDACC • Serge Verstovsek • MiloslavBeran • TaghiMansouri • Northwestern • John Crispino • Jon Licht • Mayo • Reuben Mesa • Harvard/Broad • Gary Gilliland • Ben Ebert • Todd Golub • Ann Mullally • NHLBI, NCI, HHMI, LLS, Starr Cancer Consortium, Geoffrey Beene Foundation, Gabrielle’s Angel Foundation, MPN Foundation • MSKCC • Gabriela Chiosis • Nick Socci • Marty Tallman • Omar Abdel-Wahab • Cornell • Dick Silver • Ari Melnick • Gail Roboz

More Related