PREDICTING THE LONG-TERM EFFICACY OF IFNΑ IN JAK2V617F AND CALR-MUTATED MPN PATIENTS
Author(s): ,
Amandine Tisserand
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,villejuif,France
,
Robert Noble
Affiliations:
Institut des sciences de l'evolution,Université de Montpellier,Montpellier,France
,
Matthieu Mosca
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
,
Christophe Marzac
Affiliations:
Hematologie biologique, Gustave Roussy,Villejuif,France
,
Gaelle Vertenoeil
Affiliations:
Signal transduction & molecular hematology laboratory, Ludwig Institute for Cancer Research, de Duve Institute,Université catholique de Louvain,Bruxelles,Belgium
,
Hugo Campario
Affiliations:
Laboratoire d'hématologie, inserm, umr866, CHU Dijon,dijon,France
,
Mira El Khoury
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave RoussyInserm,villejuif,France
,
Caroline Marty
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave RoussyInserm,Villejuif,France
,
Antonio Di Stefano
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave RoussyInserm,Villejuif,France
,
Nicole Casadevall
Affiliations:
Hématologie, Hôpital Saint-Antoine,Paris,France
,
Eric Solary
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
,
Florence Pasquier
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
,
Hana Raslova
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
,
Bruno Cassinat
Affiliations:
Hôpital saint-louis, service de biologie cellulaire, Assistance Publique Hôpitaux de Paris,Paris,France
,
Stefan Constantinescu
Affiliations:
Signal transduction & molecular hematology laboratory, Ludwig Institute for Cancer Research, de Duve Institute, Université catholique de Louvain,Bruxelles,Belgium
,
Jean-Jacques Kiladjian
Affiliations:
Centre d'Investigations Cliniques, Hôpital Saint-Louis,Paris,France
,
François Girodon
Affiliations:
Laboratoire d'hématologie, inserm, umr866, CHU Dijon,Dijon,France
,
Michael Hochberg
Affiliations:
Institut des sciences de l'evolution, Université de Montpellier,Montpellier,France
,
Jean-Luc Villeval
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
,
William Vainchenker
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
Isabelle Plo
Affiliations:
Inserm, umr1287, Université Paris-Sud, Gustave Roussy,Villejuif,France
(Abstract release date: 05/14/20) EHA Library. Tisserand A. 06/12/20; 295034; S214
Amandine Tisserand
Amandine Tisserand
Contributions
Abstract

Abstract: S214

Type: Oral Presentation

Session title: Deep sequencing in MPN: Mutational pathways and prognostic significance

Background

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) include Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF). These are acquired clonal disorders of hematopoietic stem cells (HSC) leading to the hyperplasia of one or several myeloid lineages. MPN are caused by three main recurrent mutations: JAK2V617F, mutations in the calreticulin (CALR) and thrombopoietin receptor (MPL) genes. Interferon alpha (IFNα) treatment induces not only a hematological response in around 70% of ET, PV and early myelofibrosis, but also a significant molecular response on both JAK2V617F- and CALR-mutated (CALRm) cells. However, a complete molecular response is only achieved in around 20% of patients.

Aims

Our aim is to predict the long-term efficacy of IFNα in JAK2V617F and CALRm patients by monitoring the fate of the disease-initiating mutated HSC in order to better stratify the molecular responders.

Methods
A longitudinal observational study (3-5 years) was performed in 50 IFNα-treated patients including 40% ET, 50% PV and 10% PMF. We followed 34 JAK2V617F patients, 14 CALRm patients and 2 MPLm patients. At 4-month intervals, the variant allele frequency was measured in mature cells (granulocytes) for each patient. Simultaneously, the clonal architecture was determined by studying the presence of the mutations in colonies derived from the different hematopoietic stem and progenitor cell populations (CD90+CD34+CD38-HSC-enriched, CD90-CD34+CD38immature and CD34+CD38+committed progenitors). We used a combination of mathematical modeling (Michor et al., Nature, 2005) and Bayesian analysis to infer the long-term behavior of mutated HSC.

Results

We observe a hematological response in around 70% of patients. Moreover, after a median follow-up of 47 months, 57% of JAK2V617F patients achieve a molecular response in mature cells, while 82% of these patients are responders in progenitors. In contrast, after a median follow-up of 35 months, only 20% of CALRm patients achieve a molecular response that is similar in all cell types.

Since it is very difficult to purify true HSC from patients, we used a combination of mathematical and statistical modeling to infer the behavior and the kinetics of IFNα-targeted mutated HSC. The model gives a good fit to all the data. It shows that JAK2V617F HSC are slowly exhausted by differentiation, which results first in an increase in the frequency of JAK2V617F progenitors and granulocytes followed with a slow decrease in their frequency. The rate of JAK2V617F homozygous HSC disappearance is more important than that of heterozygous JAK2V617F HSC and CALRm. Moreover, increasing doses of IFNα (>100 μg/week) are more efficient in targeting JAK2V617F HSC.

Finally, NGS sequencing of the associated mutations does not show any major molecular impact of IFNα. Nevertheless, in a few patients, we unmask DNMT3A mutations or observe selection of TET2 and P53 mutations.

Conclusion

Altogether, using a rigorous method of statistical inference, our results show that IFNα exhaust the human mutated HSC by differentiation into progenitors and mature cells. Our study predicts that IFNα can slowly eradicate the mutated HSC, but this beneficial effect would be more efficient: i) in patients with homozygous JAK2V617F in contrast to heterozygous JAK2V617F or CALRm and ii) with high IFNα dose. These results might explain the different outcomes in current IFNα clinical trials and will ultimately help to stratify patients for IFNα treatment.

Session topic: 15. Myeloproliferative neoplasms - Biology & Translational Research

Keyword(s): Interferon alpha, Myeloproliferative disorder

Abstract: S214

Type: Oral Presentation

Session title: Deep sequencing in MPN: Mutational pathways and prognostic significance

Background

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) include Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF). These are acquired clonal disorders of hematopoietic stem cells (HSC) leading to the hyperplasia of one or several myeloid lineages. MPN are caused by three main recurrent mutations: JAK2V617F, mutations in the calreticulin (CALR) and thrombopoietin receptor (MPL) genes. Interferon alpha (IFNα) treatment induces not only a hematological response in around 70% of ET, PV and early myelofibrosis, but also a significant molecular response on both JAK2V617F- and CALR-mutated (CALRm) cells. However, a complete molecular response is only achieved in around 20% of patients.

Aims

Our aim is to predict the long-term efficacy of IFNα in JAK2V617F and CALRm patients by monitoring the fate of the disease-initiating mutated HSC in order to better stratify the molecular responders.

Methods
A longitudinal observational study (3-5 years) was performed in 50 IFNα-treated patients including 40% ET, 50% PV and 10% PMF. We followed 34 JAK2V617F patients, 14 CALRm patients and 2 MPLm patients. At 4-month intervals, the variant allele frequency was measured in mature cells (granulocytes) for each patient. Simultaneously, the clonal architecture was determined by studying the presence of the mutations in colonies derived from the different hematopoietic stem and progenitor cell populations (CD90+CD34+CD38-HSC-enriched, CD90-CD34+CD38immature and CD34+CD38+committed progenitors). We used a combination of mathematical modeling (Michor et al., Nature, 2005) and Bayesian analysis to infer the long-term behavior of mutated HSC.

Results

We observe a hematological response in around 70% of patients. Moreover, after a median follow-up of 47 months, 57% of JAK2V617F patients achieve a molecular response in mature cells, while 82% of these patients are responders in progenitors. In contrast, after a median follow-up of 35 months, only 20% of CALRm patients achieve a molecular response that is similar in all cell types.

Since it is very difficult to purify true HSC from patients, we used a combination of mathematical and statistical modeling to infer the behavior and the kinetics of IFNα-targeted mutated HSC. The model gives a good fit to all the data. It shows that JAK2V617F HSC are slowly exhausted by differentiation, which results first in an increase in the frequency of JAK2V617F progenitors and granulocytes followed with a slow decrease in their frequency. The rate of JAK2V617F homozygous HSC disappearance is more important than that of heterozygous JAK2V617F HSC and CALRm. Moreover, increasing doses of IFNα (>100 μg/week) are more efficient in targeting JAK2V617F HSC.

Finally, NGS sequencing of the associated mutations does not show any major molecular impact of IFNα. Nevertheless, in a few patients, we unmask DNMT3A mutations or observe selection of TET2 and P53 mutations.

Conclusion

Altogether, using a rigorous method of statistical inference, our results show that IFNα exhaust the human mutated HSC by differentiation into progenitors and mature cells. Our study predicts that IFNα can slowly eradicate the mutated HSC, but this beneficial effect would be more efficient: i) in patients with homozygous JAK2V617F in contrast to heterozygous JAK2V617F or CALRm and ii) with high IFNα dose. These results might explain the different outcomes in current IFNα clinical trials and will ultimately help to stratify patients for IFNα treatment.

Session topic: 15. Myeloproliferative neoplasms - Biology & Translational Research

Keyword(s): Interferon alpha, Myeloproliferative disorder

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