Patel, Ami B.

We investigated the prognostic impact of blast counts, TP53 allelic state determinants (number of hits, del(17p), variant allele frequency, complex karyotype),and a novel karyotypic clonal cell fraction (≤50% clonal cells vs >50% clonal cells (termed ‘CK50’)) in 495 individuals with TP53- mutated ( TP53 MUT ) myeloid neoplasms. Outcome examined was 24-month survival (OS24). The cohort (median age 71) included 29% (144/495) myelodysplastic syndromes (MDS)/MDS-acute myeloid leukaemia (AML) (1%–19% blasts) and 71% (351/495) AML (≥20% blasts), with 18% (81/460) having low CK50. Overall, 83% received front-line hypomethylating agents. Higher blast counts (<20% vs ≥20%) were marginally associated with CK50 (p=0.08). In the OS24 analysis, blast count showed a marginal association with OS24 (HR 1.3 (95% CI 1.0 to 1.6); p=0.07), while CK50 predicted significantly inferior outcomes (HR=1.7 (95% CI 1.2 to 2.3); p=0.002). In a multivariable model including all TP53 allelic state determinants, only CK50 and complex karyotype remained relevant for predicting adverse outcomes.

Mastocytosis is a heterogeneous group of disorders comprising cutaneous mastocytosis, systemic mastocytosis, and mast cell sarcoma. It is associated with a variety of symptoms related to the release of mast cell mediators and mast cell tissue infiltration. Referral to specialized centers with expertise in the management of mastocytosis and multidisciplinary collaboration with subspecialists (eg, allergists for the management of anaphylaxis and drug hypersensitivities, anesthesiologists for invasive procedures or surgery, high-risk obstetrician for pregnancy) is recommended. The NCCN Guidelines for Systemic Mastocytosis provide evidence- and consensus-based recommendations for the diagnosis and comprehensive care of patients with systemic mastocytosis. The multidisciplinary panel of experts convenes at least once a year to review requested changes to the guidelines from both internal and external entities as well as to discuss data on existing and new therapies. These NCCN Guidelines Insights focus on some of the recent updates to the guidelines.

Abstract VEXAS (vacuoles, E1-ubiquitin-like modifier activating enzyme, X-linked, autoinflammatory, somatic) syndrome is a recently described autoinflammatory disorder caused by acquired UBA1 mutations in hematopoietic precursor cells. The prevalence, clinical significance, and genomic landscape of UBA1variants in patients with hematologic malignancies (HM) remains unexplored. We analyzed the genomic profiles of 86 patients carrying 17 different UBA1variants amongst an unbiased cohort of 8,976 HM patients. Specific genetic and clinical features seen more frequently in patients with UBA1 pathogenic variants (PV) versus those with variants of uncertain significance (VUS) included: marked male predominance (98% versus 80%, P=0.002), macrocytic anemia (MCV 105 ± 1.4 fl versus 96 ± 1.4 fl, p=0.01), frequent dominant clones without concurrent somatic variants (53% versus 15%, p=0.004), and association with molecularly distinct low-risk myelodysplastic syndrome (MDS; 13%) with superior overall survival (OS). Interestingly, while the genetic profiles of UBA1 PV patients resemble patients with clonal cytopenia of unknown significance (CCUS), rapid UBA1 clonal expansion predispose patients to convert to low-grade MDS with a notably hastened progression compared to UBA1 wild-type CCUS. This “clone surge to clinical stability” (CS) is a mechanism that emphasizes the unique pathobiology of UBA1mutations in VEXAS and supports it as a distinct entity.

Background. Some patients who present with clinical features consistent with idiopathic hypereosinophilic syndrome (HES; absolute eosinophil count (AEC) ≥1.5 x 10 9/L with related end organ damage) are ultimately diagnosed with a myeloid neoplasm. Although FIP1L1::PDGFRA is the most common molecular abnormality in this setting, many other fusion genes, point mutations and cytogenetic abnormalities have been implicated in driving primary (neoplastic) eosinophilia. Given the poor prognosis of these disorders in the absence of treatment and the availability of targeted therapies for many of the driver mutations, it is becoming increasingly important to rapidly identify the underlying genetic alteration. In this regard, the expense and variable sensitivity of molecular diagnostic tests remains problematic. Although clinical features have been reported to distinguish between PDGFRA-associated myeloid neoplasms and D816V KIT-positive systemic mastocytosis with hypereosinophilia, little is known about the clinical phenotypes of other subsets of patients. This multicenter retrospective study aimed to assemble a large cohort of patients with HES secondary to a myeloid neoplasm to explore the utility of clinical and laboratory features in predicting the underlying molecular abnormality. Methods. Retrospective, de-identified data from 16 centers were collected via an online Research Electronic Data Capture repository. Patients and associated data were obtained from in-house research databases and/or electronic medical record searches at each site. Clinical and laboratory data were entered in accordance with local Institutional Review Boards. Inclusion criteria were peripheral blood hypereosinophilia (AEC &gt;1.5 x 10 9/L) on at least two occasions and one of the following: ≥1 confirmed genetic abnormality recurrently associated with primary myeloid neoplasms, other evidence of clonal eosinophilia, or increased blasts (≥2% in the blood or &gt;5% but &lt;20% in the marrow). Patients with acute myeloid leukemia were excluded. Results. A total of 277 patients followed between 1990 and 2022 were included in the analysis. Median length of follow up was 31 months (range &lt;1-356), and 217/277 (78%) were alive at last follow up. The most common genetic abnormality was FIP1L1::PDGFRA (n=131) followed by D816V KIT mutations (n=39) and alterations involving JAK2 (n=22) (Figure 1). Five patients had genetic abnormalities involving two distinct genes recurrently associated with eosinophilic myeloid neoplasms. The overall median age at diagnosis was 55 years (range 12-89) and 79% of the patients were male. When patients with abnormalities involving PDGFRA and PDGFRB were excluded from the analysis, the male predominance was significantly lower at 62% (p&lt;0.001, Fisher's exact test as compared to the data set as a whole). The overall pattern of organ system involvement was similar irrespective of the underlying genetic abnormality with a few notable exceptions. Cardiac involvement was most common in patients with FIP1L1:: PDGFRA, abnormalities involving JAK2 or without pathologic alterations identified (reported in 22%, 32% and 30%, respectively); whereas skin and gastrointestinal involvement, lymphadenopathy and splenomegaly were most frequent in patients with KIT D816V. Laboratory abnormalities also differed between groups. Whereas anemia was the most common blood abnormality (reported in &gt;50% of patients), erythrocytosis was noted primarily in patients with abnormalities involving JAK2. In contrast, circulating blasts were identified in 70% of patient with BCR::ABL1 and 29% of patients with chromosomal abnormalities or KIT D816V, but in &lt;15% of patients in any of the other groups. Whereas peak AEC alone did not discriminate between the different patient groups, the AEC/tryptase ratio was increased in patients with PDGFRA-associated myeloid neoplasms, molecular abnormalities involving JAK2, or chromosomal abnormalities as compared to those with KIT mutations (Figure 2). Conclusions. Despite the limitations of retrospective data analysis, the data from this large multicenter cohort of patients with HES due to a chronic myeloid neoplasm suggest that routine demographic, clinical and laboratory features vary depending on the underlying molecular abnormality. This approach could ultimately help guide empiric therapy when molecular studies are negative or unavailable.