No abstract

No abstract

Determining response status in patients with myeloproliferative neoplasms is a complex problem requiring the integration of both structured and unstructured data elements from disparate information systems. By applying multiple techniques, a collaborative team of informatics professionals and research personnel were able to determine which elements were amenable to automated extraction and which required expert adjudication. With this knowledge in mind, we were able to build a system that joins together programmatically-derived and manually-abstracted data elements to facilitate response assessment – an important end point in clinical and translational research in this disease area.

Introduction: The progression of polycythemia vera (PV) to myelofibrosis (MF) is associated with significant morbidity and mortality. Interferon alfa (rIFNa), a disease-modifying agent, has potential to delay or prevent post-PV MF and improve overall survival but supporting data are required. We present results of the largest study demonstrating improved myelofibrosis-free and overall survival (MFS and OS) of rIFNa treated PV patients (pts) compared to other PV pts. Objectives: To estimate the MFS and OS of treated PV pts and determine the relative risk for post-PV MF and mortality of those treated with rIFNa compared to those treated with other standard therapy. Methods and Study Design: To ensure sufficient follow-up for analysis of long-term outcomes, this IRB approved study identified all adult pts treated at our center from 1974-2019 according to PVSG criteria (1974-2007), our published criteria (2008-2016) and WHO criteria (2016-2019) using a standardized query of electronic medical records. Demographic data, clinical characteristics, treatment history and outcomes were collected. The extended follow-up of this large PV cohort permitted us to evaluate the effectiveness of PV therapy using both intention-to-treat (ITT) and treatment duration (on-treatment) analyses. In the ITT analysis, pts were assigned to rIFNa or hydroxyurea (HU) arms according to the first cytoreductive treatment they received for at least one year or to phlebotomy only (PHL-O) if no cytoreductive treatment was given. On-treatment analysis was performed to account for cross-over and assess how duration of a given therapy influenced outcomes. The onset of post-PV MF was defined by IWG-MRT criteria. MFS and OS were estimated using Kaplan-Meier methods and the log-rank test compared survival between treatment arms in ITT analysis. Multivariate analysis of post-PV MF risk and mortality was performed using a Cox proportional hazards model. The model accounts for age at diagnosis and is stratified by treatment arms (ITT) or by treatment as a time-dependent covariate (on-treatment). Results: We identified 306 PV pts whose median age at diagnosis was 54 years (yr) (range 20-91) and of whom 151 (49%) were women. The median follow-up was 11 yr (range 1-45). The first line treatment was rIFNa in 75 (25%), HU in 134 (44%) or other cytoreductive regimens in 37 (12%). PHL-O was instituted in 60 pts (20%). Treatment cross-over occurred in 82 pts (27%), with the least from rIFNa arm (22%) (Table2). Treatment arms differed by age at diagnosis with a median of 50, 59 and 52 years for rIFNa, HU and PHL-O (p <0.01) (Table 3). The median MFS and OS was 19.5 and 26.3 yr for the entire group; 27 and 28 yr for rIFNa arm; 18 and 26 yr for HU arm; and 14 and 25 yr for PHL-O (log-rank p<0.01 for MFS and p=0.01 for OS) (Figure 1). In multivariate analysis that included age, rIFNa arm had a lower risk of post-PV MF or death compared to HU arm (HR 0.43, p=0.03 and HR 0.44, p=0.04 respectively) and to PHL-O arm (HR 0.22, p<0.01 and HR 0.35, p=0.03 respectively) (Figure 2). The PHL-O arm had a higher risk of post-PV MF compared to HU as well. Older age at diagnosis was a risk factor for post-PV MF and death. Accounting for cross-over, 138 pts received rIFNa at any time for a cumulative of 980 patient-years (median: 5.3, range 1-25 yr). On-treatment analysis associated rIFNa with an 8% and 7% relative risk reduction of post-PV MF and all-cause mortality respectively (age-adjusted HR of 0.92, p<0.01 and 0.93, p=0.01). Discussion: This is the largest study with the longest follow-up of rIFNa treated PV pts and the first to demonstrate that rIFNa yields superior MFS and OS compared to HU or PHL-O. This study addresses the critical issue that randomized controlled trials to date failed to answer owing to limited follow-up duration and lack of surrogate endpoints for survival. Although the median age of the entire group is younger than the reported median age at PV diagnosis, multivariate analysis showed that both the survival benefit of rIFNa and the reduced risk of fibrosis are independent of age. This study supports early use of rIFNa for PV, especially in younger patients who should not be deprived of a disease-modifying therapy for being "low risk" by consensus criteria. Conclusions: rIFNa yields improved MFS and OS of PV patients, independent of age, in this large study with extended follow up. Early use of rIFNa should be considered routinely in the management of PV. Disclosures Ritchie: agios: Other: Advisory board; Tolero: Other: Advisory board; Genentech: Other: Advisory board; Celgene, Incyte, Novartis, Pfizer: Consultancy; Ariad, Celgene, Incyte, Novartis: Speakers Bureau; Jazz Pharmaceuticals: Research Funding; Celgene, Novartis: Other: travel support; AStella, Bristol-Myers Squibb, Novartis, NS Pharma, Pfizer: Research Funding; Celgene: Other: Advisory board; Pfizer: Other: Advisory board, travel support. Silver:PharmEssentia: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Introduction. Philadelphia negative (Ph-neg) Myeloproliferative Neoplasms (MPNs) differ in clinical phenotype and outcomes despite harboring identical driver mutations. The biology behind phenotypic heterogeneity has been attributed to mutational burden, co-occurring mutations and mutation order, but remains uncertain. It is known that MPN mutations in JAK2, CALR, and MPL result in augmentation of cytokine signaling at different stages of hematopoietic differentiation towards myeloid lineages. Consistent with this, the JAK2V617F driver mutation is enriched in certain myeloid lineages compared to the hematopoietic stem and progenitor cell (HSPC) compartment (Anand et al. Blood 2011). We therefore hypothesized that the lineage-specific patterns of clonal enrichment that arise during hematopoietic differentiation from stem cells to mature progeny would account for phenotypic heterogeneity in MPNs. Methods. Peripheral blood and/or bone marrow specimens were prospectively collected from 87 MPN patients (pts) providing informed consent between July 2017 and July 2018. Data on age, gender, diagnosis, date of diagnosis, symptoms, spleen size, blood counts, bone marrow findings, mutation profile, and treatment was collected for all pts. Each specimen was deconvoluted into 11 well-defined and strictly validated hematopoietic populations using a combination of density gradient separation (Ficoll), immunomagnetic selection (CD34) and fluorescence-activated cell sorting (FACS). Final purification of specimens was performed by multiparameter FACS to isolate CD15+/CD16+ polymorphonucleated cells (PMNs), CD14+/CD11b+ monocytes, CD3+ T cells, CD19+ B cells, CD71+/CD36+ erythroblasts and 6 well-defined HSPC populations (Manz et al. PNAS. 2002, Majeti et al. Cell Stem Cell 2007). Functional and morphologic characteristics were validated for all populations. DNA was extracted from the sorted populations and the variant allelic frequency (VAF) of the driver mutation in JAK2, CALR, or MPL was quantified by droplet digital PCR. Individual patterns of mutation enrichment were represented by the VAF plotted on a hematopoietic hierarchy (Fig 1). A composite VAF hierarchy was established for each of the WHO defined MPN subtypes of Polycythemia Vera (PV), Essential Thrombocythemia (ET), and Primary Myelofibrosis (PMF) prior to treatment, during course of treatment, and in secondary myelofibrosis. Clustering of individual patterns in relation to composite trees was performed using principal component analysis (PCA), which allowed clinical validation of clustering patterns. Results. A total of 135 samples were collected from 87 pts. Demographic and clinical features of the cohort are shown in Table 1. The composite pattern of MPN mutation enrichment differed in PV, ET and PMF (Fig 1). Pts with untreated PV or ET harbored a small proportion of mutated stem cells. The VAF in PV patients implied clonal dominance in mature myeloid progeny while there was minimal enrichment of the driver mutation in pts with JAK2 ET. In comparison, pts with PMF had a significantly higher VAF in the HSC compartment, but had minimal enrichment of the driver mutation during myeloid differentiation. Using PCA, individual patterns from a sample of 34 JAK2V617F MPN pts were clustered in reference to the pre-established composite patterns (heatmap in Fig. 2). This was done in order to validate consistency of patterns with clinical diagnoses (see example in Fig 2). Finally, we found that interferon treated PV pts had a unique decline in VAF with myeloid differentiation (Fig 3) but persistence of the mutant allele within the stem cell compartment: a finding that potentially explains the persistence of bone marrow abnormalities in pts achieving molecular response determined by whole blood (WB) VAF. Conclusion. The pattern of clonal enrichment of an MPN stem cell during hematopoiesis is unique to individual pts and varies significantly among the 3 major WHO subtypes of PV, ET, and PMF. This pattern also differs in relation to the disease stage, and is informative of treatment effects. WB VAF does not predict the proportion of immature HSPC harboring driver mutation. For these reasons, evaluating the clonal heterogeneity of MPN driver mutations, particularly those in HSPCs, may provide a useful surrogate measure to qualify response to novel agents in pre-clinical and clinical studies in MPNs. This is currently being tested. Disclosures Ritchie: NS Pharma: Research Funding; Incyte: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Research Funding; ARIAD Pharmaceuticals: Speakers Bureau; Astellas Pharma: Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Celgene: Consultancy, Other: Travel, Accommodations, Expenses, Speakers Bureau.