Treatment With Pegylated Interferon-Alpha in Philadelphia Chromosome Negative Chronic Myeloproliferative Neoplasms: Clinical and Molecular Aspects of Therapy

Publikation: Bog/antologi/afhandling/rapportPh.d.afhandlingpeer review

Abstrakt

Summary, English
The Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) comprise essential thrombocythemia, polycythemia vera, pre-fibrotic myelofibrosis, and primary myelofibrosis. MPN are clonal hematopoietic stem-cell neoplasms characterized by uncontrolled proliferation of cells derived from the myeloid lineage. The diseases are associated with enhanced morbidity and mortality, mainly related to an increased risk of thrombohemorrhagic events.
Internationally, hydroxyurea (HU) is the most widely used cytoreductive agent for patients with MPN. HU reduces the risk of thrombosis. However, long-term treatment has been suggested to increase the risk of leukemic transformation. As an alternative, recombinant interferon-alpha (IFNα), a potent immunomodulating and non-leukemogenic agent, has been used off-label for the treatment of MPN for more than 30 years. Although IFNα has been demonstrated to induce high clinical, hematologic, and molecular response rates in numerous non-randomized trials, the widespread use of IFNα has been hampered due to pronounced toxicity. However, the introduction of pegylated IFNα formulations, with improved tolerability and preserved efficacy, has renewed the interest in IFNα as a first-line treatment option in MPN. Importantly, long-term treatment (> 5 years) may induce "minimal residual disease", with a mutated JAK2V617F allele burden ≤ 1% in concert with normalization of the bone marrow, which may be sustained in a subset of patients even after treatment discontinuation. Based on these observations, IFNα has been suggested to possess disease-modifying capacity with the potential to alter the natural history of the disease. However, optimal first-line cytoreductive therapy for patients with MPN remains to be established.
The objective of the research included in this thesis was to investigate and compare the clinical and molecular aspects of cytoreductive therapy with IFNα or HU in Danish patients with MPN based on data obtained from the DALIAH trial (Danish trial of low-dose interferon-alpha versus hydroxyurea in the treatment of patients with Philadelphia chromosome-negative myeloproliferative neoplasms, ClinicalTrials.gov identifier: NCT01387763). The DALIAH trial is an investigator-initiated, open-label, randomized controlled, phase III clinical trial comparing IFNα head-to-head with HU in patients with newly diagnosed MPN.
In manuscript I, we evaluated the efficacy and safety of IFNα compared with HU. We observed no significant differences in the molecular or complete clinicohematologic response (CHR) rates by intention-to-treat analysis within 36 months between IFNα and HU. However, response kinetics differed markedly between the two treatment groups. Patients in the HU group displayed a rapid but only transient increase in the molecular response rate. In contrast, a gradual increase in the molecular response rate over time was observed among patients receiving IFNα, reflected by a continuous reduction in the median JAK2V617F allele burden with no evidence of plateau at data cut-off. Despite applying a low-dose regimen, the IFNα discontinuation rate was high (55% at 36 months). However, the annual discontinuation rate was similar to that of HU in the third year of treatment. Importantly, patients tolerating IFNα demonstrated higher molecular and complete clinicohematologic efficacy than HU beyond two and three years of treatment, respectively, by per-protocol analysis.
In manuscript II, we investigated the impact of somatic mutations on response and resistance to cytoreductive therapy by sequential genomic profiling at baseline and after 24 months of therapy. The presence of specific somatic mutations at baseline did not predict the achievement of CHR at 24 months. However, among JAK2V617F-mutated patients, those achieving CHR had a greater reduction in the JAK2V617F allele burden than those who did not achieve CHR. In contrast, the CALR allele burden did not decline significantly among those achieving CHR or those not achieving CHR. The most common treatment-emergent mutations were detected in DNMT3A. Mutated DNMT3A was significantly more frequent among patients receiving IFNα than HU, whereas mutations in PPM1D and TP53 were enriched in the HU group, indicating that clonal evolution is dependent on the choice of cytoreductive treatment. In addition, mutated DNMT3A was more prevalent in IFNα treated patients failing to achieve CHR, suggesting that mutated DNMT3A confer resistance to IFNα.
Collectively, the research included in this thesis provides novel information on the clinical and molecular aspects of cytoreductive therapy with IFNα or HU in patients with MPN. We found distinct treatment- and mutation-specific patterns of response and identified mutated DNMT3A as a potential predictor of IFNα resistance. However, additional prospective clinical trials with long-term follow-up are required to validate our findings and firmly identify biomarkers predicting treatment outcome, preferably already at the time of diagnosis, to enable personalized prediction of outcome and establish the optimal first-line cytoreductive therapy for the individual patient with MPN.


Dansk resumé (Summary, Danish)
De Philadelphia-kromosom negative myeloproliferative neoplasier (MPN) omfatter essentiel trombocytose, polycytæmia vera, præfibrotisk myelofibrose samt primær myelofibrose. MPN er klonale stamcellesygdomme karakteriseret ved ukontrolleret deling af myeloide celler. Sygdommene er associeret med øget morbiditet og mortalitet, hvilket primært tilskrives en forhøjet risiko for trombose og blødning.
Hydroxyurea (HU) er det internationalt mest anvendte cytoreducerende lægemiddel til patienter med MPN. HU reducerer risikoen for trombose, dog øger langvarig behandling muligvis risikoen for leukæmisk transformation. Gennem mere end 30 år har man derfor benyttet rekombinant interferon-alfa (IFNα), hvilket er et potent immunmodulerende og non-leukæmisk stof, som alternativ. På trods af at IFNα i talrige ikke-randomiserede studier givet anledning til høje kliniske, hæmatologiske og molekylære responsrater, har IFNα ikke vundet indpas i behandlingen af MPN grundet udtalt toksicitet. Dog har udvikling af pegylerede former af IFNα, med en forbedret toksicitetsprofil samt uændret effektivitet, givet anledning til fornyet interesse for IFNα som et muligt førstelinje behandlingsvalg ved MPN. Ved langvarig behandling med IFNα (> 5 år) er det muligt at opnå ”minimal restsygdom”, defineret ved en lav muteret JAK2V617F allelbyrde samt normalisering af knoglemarven, som kan fastholdes hos en andel af patienterne gennem flere år, selv efter behandlingsophør. På baggrund af disse observationer formoder man, at IFNα muligvis har potentiale til at ændre det naturlige sygdomsforløb ved MPN. Imidlertid er den optimale første-linje behandling til patienter med MPN ikke endeligt klarlagt.
Formålet med denne Ph.d. og de inkluderede delarbejder var, at undersøge og sammenligne de kliniske og molekylære aspekter af cytoreduktiv behandling med IFNα og HU hos danske patienter med MPN baseret på data genereret i DALIAH-studiet (Dansk studie af lavdosis interferon-alfa versus hydroxyurea i behandling af patienter med Philadelphia kromosom-negative myeloproliferative neoplasier, ClinicalTrials.gov id: NCT01387763). DALIAH-studiet er et dansk investigator-initieret, open-label, randomiseret-kontrolleret, klinisk fase III forsøg, der direkte sammenligner IFNα med HU hos patienter med MPN.
I manuskript I undersøgte vi effekt og sikkerhed af IFNα overfor HU. Vi fandt ingen forskel mellem IFNα og HU ift. at opnå molekylært eller komplet klinisk-hæmatologisk respons (CHR) indenfor 36 måneders behandling ved intention-to-treat analyse. Derimod afdækkede analysen markante forskelle i responsmønstre mellem behandlingsgrupperne. Patienter i behandling med HU havde en hurtigt indsættende men blot kortvarig øgning i det molekylære respons. I modsætning hertil steg den molekylære responsrate gradvist over tid blandt patienter i behandling IFNα reflekteret ved en kontinuerlig reduktion i JAK2V617F-allelbyrde uden tegn på affladning ved data cut-off. Frafald fra IFNα-behandlingen var høj (55% ved 36 måneder) på trods af lav dosering. Dog var den årlige seponeringsrate for IFNα sammenlignelig med HU det tredje år af behandlingen. Desuden er det vigtigt at fremhæve, at patienter som tålte behandlingen med IFNα, havde et signifikant højere molekylært og komplet klinisk-hæmatologisk respons ved per protokol analyse sammenlignet med HU efter henholdsvis to og tre års behandling.
I manuskript II undersøgte vi betydningen af somatiske mutationer i forhold til behandlingsrespons og resistens ved hjælp af next-generation sequencing ved henholdsvis baseline og efter 24 måneders behandling. Påvisning af specifikke somatiske mutationer ved baseline prædikterede ikke for CHR ved 24 mdr. Blandt patienter med JAK2V617F-mutationen havde de der opnåede CHR dog en større reduktion i den muterede allelbyde end de der ikke opnåede CHR. Derimod faldt den muterede CALR allelbyrde ikke signifikant hverken blandt de der opnåede CHR og de der ikke gjorde. De hyppigste nye mutationer påvist under pågående behandling blev detekteret i DNMT3A. Blandt patienter i behandling med IFNα var muteret DNMT3A det hyppigst muterede gen, hvorimod mutationer i PPM1D og TP53 var hyppigere hos patienter i behandling med HU, hvilket indikerer, at den klonale udvikling afhænger af valget af cytoreduktiv behandling. Desuden var nye mutationer i DNMT3A, signifikant hyppigere forekommende hos IFNα-behandlede patienter, der ikke opnåede CHR, hvilket tyder på, at muteret DNMT3A inducerer IFNα resistens.
Samlet set bidrager denne afhandling med ny information vedrørende de kliniske og molekylære aspekter af første-linje cytoreduktiv behandling med IFNα og HU hos patienter med MPN. Vi fandt behandlings- og mutationsspecifikke responsmønstre og identificerede muteret DNMT3A som en mulig årsag til IFNα-resistens. Yderligere prospektive studier med lang opfølgningsperiode er dog nødvendige for at validere resultaterne præsenteret i denne afhandling. Sådanne studier er desuden nødvendige for at identificere biomarkører, der kan prædikere behandlingsrespons, gerne allerede på diagnosetidspunktet, hvorved personlige behandlingsstrategier kan etableres og det mest optimale første-linje behandlingsvalg kan tilbydes til den enkelte patient med MPN.

OriginalsprogEngelsk
ForlagUniversity of Copenhagen, Faculty of Health and Medical Sciences
StatusUdgivet - 15 dec. 2021

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