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PURPOSE Management of locally advanced rectal cancer (LARC) includes neoadjuvant chemoradiotherapy (NACRT) followed by total mesorectal excision. Recently, total neoadjuvant treatment (TNT) has gained attention. In developing countries, patients with rectal cancer often present at advanced stages. This study assesses treatment patterns and outcomes in LARC at a largest referral center in Ethiopia. MATERIALS AND METHODS A cross-sectional study was conducted on 100 patients with LARC treated at Tikur Anbessa Specialized Hospital from January 2020 to September 2022. RESULTS The median age at diagnosis was 45.5 years (range, 20-86), with 51% male. Of the patients, 81% had no previous oncologic treatment and 75.3% was discussed in a multidisciplinary tumor board. Up-front surgery was planned for 44.4% of patients, whereas 22.2% and 8.6% were assigned to TNT and NACRT, respectively. Among 81 treatment-naïve patients, 79 were triaged for surgery, but only 47 (59.5%) underwent surgery, achieving an 89.9% R0 resection rate. Of 36 up-front planned surgeries, 35 proceeded as planned, whereas only 12 of 43 (28%) planned after neoadjuvant treatment underwent surgery. Neoadjuvant chemotherapy (NACT) was given to 37% of patients, with 16.7% (5 of 30) undergoing subsequent surgery. Radiotherapy was given to 24.2% of participants, with 56.25% undergoing surgery. Short-course radiotherapy (SCRT) was given to two patients. Only 14.8% completed all planned treatments, with radiation waiting time (median, 10 months) being the main impediment. CONCLUSION Timely administration of neoadjuvant treatment is not possible in most resource-limited settings. Because of better treatment completion, up-front surgery looks a more viable option than NACT in these situations. Extended waiting time for radiotherapy can be mitigated by opting for alternatives like SCRT in selected patients.

Abstract The antiapoptotic protein, myeloid cell leukemia-1 (Mcl-1), contributes to the pathophysiology of acute myeloid leukemia (AML) and certain B-cell malignancies. Tumor dependence on Mcl-1 is associated with resistance to venetoclax. Voruciclib, an oral cyclin-dependent kinase (CDK) inhibitor targeting CDK9, indirectly decreases Mcl-1 protein expression and synergizes with venetoclax in preclinical models. This dose escalation study evaluated voruciclib in patients with previously treated hematologic malignancies. Initially, voruciclib was administered daily, continuously, on a 28-day cycle (group 1). After 2 patients with prior allogeneic stem cell transplantation had a dose-limiting toxicity (DLT) of interstitial pneumonitis at 100 mg, voruciclib administration was changed to days 1 to 14 of a 28-day cycle (group 2). Forty patients, 21 with AML and 19 with B-cell malignancies, were enrolled. Patients had a median of 3 prior lines of therapy (range, 1-8). Dose escalation in group 2 was stopped at 200 mg, a dose that achieved plasma concentrations sufficient for target inhibition, without DLTs observed. The most common adverse events were diarrhea (30%), nausea (25%), anemia (22%), fatigue (22%), constipation (17%), dizziness (15%), and dyspnea (15%). In AML, 1 patient achieved a morphologic leukemia-free state, and 2 had stable disease. Voruciclib treatment led to a decrease in MCL1 messenger RNA expression, downregulation of myelocytomatosis (MYC) and NF-κB transcriptional gene sets, and reduced phosphorylation of RNA polymerase 2. Voruciclib on intermittent dosing was well tolerated, with no DLTs, paving the way for evaluation of the combination of voruciclib with venetoclax for patients with previously treated AML. This trial was registered at www.clinicaltrials.gov as #NCT03547115.

ABSTRACT Patients with newly diagnosed acute myeloid leukemia (ND‐AML) derive variable survival benefit from venetoclax + hypomethylating agent (Ven‐HMA) therapy. The primary objective in the current study was to develop genetic risk models that are predictive of survival and are applicable at the time of diagnosis and after establishing treatment response. Among 400 ND‐AML patients treated with Ven‐HMA at the Mayo Clinic, 247 (62%) achieved complete remission with (CR) or without (CRi) count recovery. Multivariable analysis–derived hazard ratios (HR), including 1.8 for European LeukemiaNet (ELN) adverse karyotype, 4.7 for KMT2Ar , 1.7 for TP53 MUT , 2.6 for KRAS MUT , and 2.1 for IDH2 WT were applied to develop an HR‐weighted risk model: low, intermediate, and high; respective median survival censored for allogeneic stem cell transplant (ASCT) (3‐year survival) were “not reached” (67%), 19.1 (33%), and 7.1 months (0%). In patients achieving CR/CRi, adverse karyotype, KMT2Ar , KRAS MUT , IDH2 WT predicted inferior survival, allowing for a complementary response‐stratified risk model. The model was externally validated and was shown to be superior to the ELN 2024 risk model (AIC 179 vs. 195 and AUC 0.77 vs. 0.69). Survival was inferior with failure to achieve CR/CRi or not receiving ASCT; 3‐year survival for high‐risk with or without ASCT was 42% versus 0% ( p < 0.01); intermediate 72% versus 43% ( p = 0.06); and low‐risk 88% versus 78% ( p = 0.53). The Mayo genetic risk models offer pre‐treatment and response‐based prognostic tools for ND‐AML treated with Ven‐HMA. The current study underscores the prognostically indispensable role of achieving CR/CRi and ASCT.

Background: Venetoclax in combination with hypomethylating agents (HMA) or low dose cytarabine is the standard of care for patients (pts) with newly diagnosed AML ineligible for intensive chemotherapy. However, responses are transient, and loss of response is associated with poor outcome. The antiapoptotic protein Mcl-1 promotes cell survival in AML and its overexpression is associated with resistance to venetoclax. Voruciclib, a potent oral CDK9 inhibitor (CDK9i), indirectly decreases Mcl-1 protein expression, and has synergistic activity with venetoclax in AML preclinical models. In the initial part of this study in 40 pts with R/R AML and B-cell malignancies, voruciclib at doses up to 200 mg administered on days 1-14 in a 28-day cycle was well tolerated, had no dose limiting toxicities (DLTs), and showed biologic and clinical activity in heavily pretreated pts (Blood 2023:142; Supp 1:4286). We hypothesized that voruciclib in combination with venetoclax may achieve greater antileukemic effect. Methods: Pts with R/R AML were eligible if aged ≥18 years, ECOG performance status ≤1, adequate organ function, and no prior CDK9i therapy. Dose escalation followed a 3+3 design, and DLTs were assessed in Cycle 1. Voruciclib was administered at 7 dose levels between 50 mg and 300 mg on days 1-14 of 28-day cycles. Venetoclax was administered at 200 mg on days 1-21 and 400 mg on days 22-28. Disease response was assessed by the 2017 ELN criteria. Mcl-1 protein expression and phosphorylation of RNA Pol IISer2 were evaluated in PBMC in cycle 1. The study is registered at clinicaltrials.gov (NCT03547115). Results: Enrollment in this portion of the study is complete with 41 pts. Median age was 67 years (range 34-89). Median number of prior lines of therapy was 2 (range 1-7), with 93% of pts having received venetoclax and HMAs, 51% having received an anthracycline, and 20% having had prior allogeneic hematopoietic stem cell transplant (HSCT). 2017 ELN risk was adverse in 73% of pts and intermediate in 17%. The median duration on therapy was 1.5 months (range 0.2 to 9+). No DLTs were observed, and based on PK/PD analysis, dose escalation was stopped at 300 mg without reaching the maximum tolerated dose. The most common adverse events (all grades/grade ≥3) were nausea (32%/0%), febrile neutropenia (27%/24%), dyspnea (22%/2%) diarrhea (22%/2%), hypokalemia (22%/5%) and thrombocytopenia (22%/20%). Seven pts died during treatment, 5 due to an infection and 2 due to hemorrhagic events. Anti-leukemic activity was observed in 10 (31%) of 32 pts treated with voruciclib at doses from 100-300 mg; 2 pts had CRi (one referred to HSCT and one with 6 months of remission prior to progression), 1 pt had MLFS (ongoing at 9 months), and 7 pts had stable disease lasting ≥3 months. Among 25 pts with circulating peripheral blood blasts, 18 (75%) showed a significant reduction of circulating blasts by day 14 of the first cycle; however, circulating blasts increased again in 8 of 18 pts during single agent venetoclax administration on days 15 to 28. Voruciclib pharmacokinetics (PK) was dose proportional. At 300 mg steady state, mean AUC0-24 was 21,526 ng x hr/mL and mean Ctrough was 644 ng/mL, exceeding concentrations needed for target inhibition in preclinical models. Voruciclib did not affect venetoclax PK. Pharmacodynamic studies including Mcl-1 protein expression and RNA Pol IISer2 phosphorylation in PBMC by flow cytometry showed on target effects and is reported separately. Conclusion: The combination of voruciclib with venetoclax is well-tolerated and has activity in pts with AML and disease progression after venetoclax. Because of the rebound in peripheral blasts after 14 days off voruciclib, voruciclib administered on days 1-21 per cycle merits further evaluation.

Background: TP53-mutated (TP53mut) myeloid neoplasms (MN) have particularly poor survival. Discrepancies in defining TP53mut MN have impact on diagnostic work up, therapeutic decisions, and clinical trial enrolment. Methods: MN cases harboring TP53mut (variant allele frequency, VAF ≥2%) were classified based on bone marrow (BM) and peripheral blood (PB) blast % using the 4th revision of the WHO classification (WHO-4R). Biallelic loss was defined as (i) ≥2 mutations each with VAF ≥2%; (ii) single TP53mut VAF ≥2% plus 17p loss detected on karyotype, FISH, or SNP; or (iii) single TP53mut VAF ≥50%, whereas monoallelic loss was defined as single TP53mut VAF &lt;50% without 17p loss. Primary endpoint was overall survival (OS) from diagnosis. Conditional Inference Trees (CIT) analysis was used to determine the true effect of a predictor. Results: We identified 580 cases including WHO-4R defined acute myeloid leukemia (AML, BM/PB blasts ≥20%, n=219, 37.8%), myelodysplastic syndrome (MDS) with excess blasts-2 (EB-2, BM 10-19% or PB 5%-19%, n=92, 15.9%), MDS with excess blasts-1 (EB-1, BM 5-9% or PB 2-4%, n=75, 12.9%), and the remaining were MDS with low blasts (-LB, BM &lt;5% and PB ≤1%, n=194, 33.4%). Of the 578 cases evaluable for allelic status, 437 (75.6%) and 141 (24.4%) had biallelic and monoallelic TP53 loss, respectively. Higher frequency of biallelic loss was observed with increasing blasts. 63.2%, 73.3%, 78% and 86.3% of cases with MDS-LB, MDS-EB1, MDS-EB2, and AML had bi-allelic TP53 loss (P&lt;0.0001). In a multivariable analysis, WHO-4R categories, VAF ≥10%, and biallelic loss were independent predictors of poor survival. CIT analysis further stratified the cohort into 4 groups with distinct survival: (1) MDS-LB (n=194, 33.4%); (2) MDS-EB1/EB2 and AML with VAF &lt;10% (n=38, 6.6%); (3) MDS-EB1/EB2 with VAF ≥10% (n=149, 25.7%); and (4) AML with VAF ≥10% (n=199, 34.3%). MDS-LB cases could be further stratified based on allelic status and complex karyotype (CK): OS was poor for cases with biallelic TP53 loss and monoallelic TP53mut with CK compared to monoallelic TP53mut without CK, who had the most favorable survival (12.7 vs. 13 vs. 34.8 months, P&lt;0.0001).MDS-EB1/EB2/AML with VAF&lt;10% could also be stratified by CK: MDS-EB1/EB2/AML with VAF&lt;10% cases without CK had the favorable survival compared to their counterparts with CK and MDS-EB1/EB2 with VAF ≥10% cases (26.2 vs. 5.6 vs. 6.3 months, P=0.003).MDS-EB1/EB2 with VAF ≥10% was a homogenous subgroup: Biological characteristics including the proportion of cases with biallelic TP53 loss, CK (P&gt;0.9), monosomal karyotype (MK, P&gt;0.9), del 5q (P=0.6), del 7q (P=0.4), and del 17p (P=0.2) were comparable between MDS-EB1 and -EB2 with VAF ≥10%. Importantly, median OS of MDS-EB1 and EB2 with VAF ≥10% was comparable (9.6 vs. 7.2 months, P=0.12). OS in this group was comparable regardless of the blast %, allelic status, or presence of CK.AML with VAF ≥10% had extremely poor survival: Median OS was 3.9 months. Survival of AML was equally poor irrespective of the mono- or biallelic (3.6 vs. 3.9, P=0.89) and non-CK vs. CK (1.8 vs. 3.9 months, P=0.09). Combined, our model would acknowledge poor survival of 514 (89.1%) cases. In contrast, retrospective application of the 5th edition of the WHO classification (WHO-5) and International Consensus Classification (ICC) would classify only 211 (36.4%) and 468 (80.7%) cases as biallelic/multi-hit TP53mut MN, respectively. Finally, the Harrell's c-index of the proposed model, WHO-5, and ICC was 0.66, 0.571, and 0.617, respectively. Conclusion: We provide evidence for subsequent refinements in classifying MN harboring TP53mut. Our salient findings include: (i) acknowledgement of CK as ‘biallelic equivalent’ in MDS-LB; as well as EB1/EB2/AML with VAF 2 to &lt;10% cases; and (ii) demonstration of poor survival of MDS-EB1 and -EB2 with VAF ≥10% regardless of the allelic status. In conclusion, our proposed model acknowledged poor survival of a higher proportion of cases as TP53mut MN compared to the current models with a higher c- index.

Background Venetoclax + hypomethylating agent (Ven-HMA) therapy results in favorable response rates (CR/CRi 66%) and overall survival (OS; median 14.7 months) in unfit patients with newly-diagnosed acute myeloid leukemia (ND-AML; N Engl J Med 2020;383). However, there is substantial heterogeneity in individual patient outcomes based on response to treatment. The objective of the current study was to develop a genetic risk model to predict survival outcome in treatment responders and non-responders, analyzed separately, and also account for allogeneic stem cell transplant (ASCT). Methods Treatment-naïve AML patients receiving Ven-HMA, outside of a clinical trial, at the Mayo Clinic, USA (MN, AZ, FL) were retrospectively recruited. Molecular studies (48-gene panel) were performed by next-generation sequencing. Response was assessed according to the 2022 European LeukemiaNet (ELN) criteria (Blood 2022;140). Standard statistical analyses were performed using JMP Pro (Version 17.0.0). Results 400 ND-AML patients (median age 73 years, 64% male, 60% de novo) received Ven-HMA. ELN cytogenetic risk included favorable 2%, intermediate 60%, or adverse 38%. Mutations involved TP53 in 26%, TET2 19%, RUNX1 19%, SRSF2 18%, ASXL1 18%, DNMT3A 15%, K/NRAS 13%, NPM1 12%, IDH2 12%, FLT3-ITD 10%, IDH1 7% and DDX41 in 4% of informative cases. 153 (38%) patients achieved CR, 94 (24%) CR with incomplete count recovery (CRi), resulting in CR/CRi in 247 (62%) patients. CR/CRi rates were higher with NPM1 (86% vs 59%), IDH2 (77% vs 60%), and DDX41 mutations (93% vs 61%) and lower with TP53 (45% vs 67%), FLT3-ITD (41% vs 64%), RUNX1 (49% vs 65%) mutations and adverse karyotype (48% vs 71%), with all retaining significance in multivariable analysis. CR/CRi rate was highest (87%) in 75 patients with one or more favorable mutations (NPM1, IDH2, DDX41) and no unfavorable mutation (TP53, FLT3-ITD, RUNX1). CR/CRi rate was lowest in 171 patients with at least one unfavorable mutation and no favorable mutation (44%; p&lt;0.01). After a median follow up of 10.5 months (0.5-66), 105 relapses (43% of patients in CR/CRi), 248 (62%) deaths and 65 (16%) ASCT were documented. Univariate analysis for transplant-censored OS disclosed superior survival in patients achieving CR/CRi (median 21 vs 3.6 months; HR 5.4, 95% CI 4.1-7.1). Among patients achieving CR/CRi, IDH2 mutation was associated with superior (median not reached vs 20.5 months) and male gender (median 17.6 vs 29.2 months), TP53 mutations (median 11.9 vs 24.3 months) and adverse karyotype (median 12.6 vs 29.4 months) with inferior survival; multivariable analysis resulted in HRs (95% CI) of 2.1 (1.3-3.4) for male gender, 2.1 (1.2-3.8) for adverse karyotype, and 2.5 (1.1-5.7) for absence of IDH2 mutations. Male gender did not show an association with karyotype, or TP53 mutations (p&gt;0.1). Accordingly, an HR-weighted genetic risk model was generated with assignment of one point each to male gender, adverse karyotype, and absence of IDH2 mutation: high risk = 3 risk factors (n=38; median 9.6 months; 3-year survival 0%); intermediate risk = 2 risk factors (n=129; median 22 months; 3-year survival 38%); and low-risk = ≤1 risk factor (n=78; median not reached; 3-year survival 69%; p&lt;0.01). In patients bridged to ASCT (n=60), post-transplant survival was inferior in the presence of ≥ 2 risk factors (n=42; median 46 months) vs. ≤1 risk factor (n=18; median not reached; p=0.1). In patients not achieving CR/CRi, risk factors for OS included male gender (median 3.4 vs 6.1 months), adverse karyotype (median 3.3 vs 4.5 months) and TP53 mutation (median 3.1 vs 4.5 months) while those with IDH2 mutations lived longer (median 8.4 vs 3.4 months). In multivariable analysis, HRs (95% CI) were 1.9 (1.3-2.9) for male gender, 2.0 (1.4-2.9) for adverse karyotype, and 2.1 (1.1-4.3) for absence of IDH2 mutations. OS was shortest for non-responders harboring 3 risk factors (n=45; median 3 months; 1-year survival 0%) and longer for those harboring two (n=80; median 6 months, 1-year OS 15%) or ≤ 1 risk factor (n=25; median 14 months; 1-year OS 56%; p&lt;0.01). Conclusion The current study describes a molecular profile for predicting response to Ven-HMA in ND-AML and also introduces a novel approach to survival prediction that considers treatment response as the starting point. In both responders and non-responders, male gender and adverse karyotype were identified as unfavorable and IDH2 mutation favorable risk factor for OS.

Background Venetoclax + hypomethylating agent (Ven-HMA) therapy has demonstrated improved outcomes in elderly/unfit patients with newly-diagnosed acute myeloid leukemia (ND-AML) (N Engl J Med 2020;383). However, ~50% of patients who respond to Ven-HMA, eventually relapse (Am J Hematol 2024;99). In the current study we examined the prognostic contribution of gene mutations, karyotype, measurable residual disease (MRD) status and clinical risk factors for relapse in patients with ND-AML treated with Ven-HMA therapy. Methods Our study population of ND-AML was retrospectively recruited from Mayo Clinic (MN, AZ, FL), after institutional review board approval and based on documentation of complete remission with/without count recovery (CR/CRi) following Ven-HMA therapy. Relapse-free survival was determined from the time of remission to relapse or last follow-up. Survival analysis was censored for transplant. The 2022 European LeukemiaNet (ELN) criteria was used to assign cytogenetic risk and classify treatment response (Blood 2022;140). Standard statistical analyses were performed using JMP Pro (Version 17.0.0). Results 247 ND-AML patients treated with Ven-HMA (median age 73 years, 62% male, 64% de novo) who achieved CR (n=153), or CRi (n=94) were included. MRD by multiparameter flow cytometry (sensitivity 0.01%) performed at the time of CR/CRi, was negative in 117 (70%) of 166 informative cases. ELN cytogenetic risk categories at diagnosis included favorable 2%, intermediate 69%, or adverse 29%. Mutations involved TET2 21%, SRSF2 21%, TP53 19%, ASXL1 18%, DNMT3A 18%, NPM1 17%, IDH2 15%, RUNX1 15%, K/NRAS 12%, IDH1 8%, FLT3-ITD 7%, and DDX41 in 6% of informative cases. Relapse was documented in a total of 99 (40%) patients who achieved CR (39%) or CRi (41%) after a median remission duration of 6 months (1-31). Patients that relapsed within the first-year vs those that did not, were more likely to be males (75% vs 55%), MRD positive (44% vs 24%), and harbor TP53 mutations (23% vs 16%). Univariate analysis for RFS identified male gender (12 vs 29 months; p=0.02), secondary AML (10 vs 21 months; p&lt;0.01), adverse karyotype (9 vs 22 months; p&lt;0.01), TP53 mutations (6 vs 18 months, p&lt;0.01) and MRD positive remission (13 months vs not reached; p&lt;0.01) as risk factors for relapse; on the other hand, IDH2 mutations (not reached vs 15 months; p&lt;0.01) were associated with a lower risk of relapse. Multivariable analysis confirmed male gender (HR 2.2), TP53 mutations (HR 3.0) and MRD positive remission (HR 1.7) as unfavorable predictors of relapse. Subsequently, in a three-tiered relapse prediction model, RFS was significantly inferior in the presence of three risk factors (male gender, TP53 mutations, MRD positive remission) (n=10, median 4 months), vs two (n=34, median 10 months) vs ≤ 1 risk factor (n=122, median 31 months) (p&lt;0.01); 1-year cumulative incidence of relapse was 100%, 56%, and 26% in the presence of three, two and ≤ 1 risk factors, respectively. 50 of 99 (65%) patients received salvage therapy which included cladribine-cytarabine-Ven (n=19), intensive induction chemotherapy (n=9), FLT3 inhibitors (n=5), Ven-HMA-FLT3 inhibitor (n=1), IDH1/2 inhibitors (n=5), glasdegib-cytarabine (n=4), gemtuzumab (n=3), lenalidomide (n=1), or investigational therapies (n=3); in addition, Ven-HMA was resumed in 14 patients in whom treatment had been discontinued for a median of 5 months (2-12). Overall, 20 (31%) of patients achieved second CR/CRi and response rates were similar with intensive vs less intensive therapy (CR/CRi; 44% vs 29%; p=0.37). Median follow up after relapse was 3.4 months (1-66), during which 73 (74%) deaths, and 4 (5%) ASCT were recorded. Median transplant-censored survival was 4.2 months (1-year; 22%), and inferior in patients with adverse karyotype (median 4.6 vs 3.4 months; p=0.02), and TP53 mutations (3.6 vs 4.4; p=0.11); on the other hand, male gender (3.5 vs 6.8 months; p=0.51), MRD positive remission (4.6 vs 4.2; p=0.56), and IDH2 mutations (6.7 vs 4.2; p=0.28), did not influence post-relapse survival. Conclusions The current study identifies male gender, TP53 mutations, and MRD status as powerful predictors of relapse and proposes a relapse prediction model for ND-AML patients receiving Ven-HMA therapy. Furthermore, relapse following Ven-HMA was associated with uniformly poor outcomes, regardless of salvage treatment strategy.

Background The prognostic relevance of TP53 mutations (TP53MT) in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has been extensively studied and the information accessed for defining the new International Consensus Classification (ICC) category of “myeloid neoplasms with mutated TP53” (Blood 2022;140:1200). The latter designation requires ≥10% TP53 variant allele frequency (VAF) for AML and MDS/AML and in case of MDS, multi-hit TP53 or ≥10% VAF associated with complex karyotype (CK). We examined the prognostic relevance of TP53MT in myeloproliferative neoplasms (MPN), specified by subtype and disease stage. Methods The current study was conducted under an institutional review board approved minimum risk protocol. Additional informative cases from the University of Florence, Italy and the South Australian Myeloid Neoplasm Registry were included. Diagnostic criteria and assignment of TP53 allelic state were according to the ICC. Next-generation sequencing (NGS) and cytogenetic studies were performed according to institutional standard protocols. Conventional statistical methods were employed. Survival analyses were censored for allogeneic stem cell transplantation (ASCT) and were calculated from the time of first detection of TP53MT. Results 115 patients with MPN and documented pathogenic TP53MT were considered (median age 68.5 years). ICC-defined subtype designations, at time of TP53MT detection, were polycythemia vera (PV) or essential thrombocythemia (ET) (N=9), chronic phase myelofibrosis (MF-CP; N=63), accelerated phase MPN (MPN-AP; N=16), and blast phase MPN (MPN-BP; N=27). Driver mutation distribution was JAK2 64%, CALR 18%, MPL 8%, and triple-negative 10%. Karyotype was monosomal (MK) in 42%, CK 9%, and normal (NK) 35%. Frequent co-mutations were ASXL1 (28%), TET2 (14%), and SRSF2 (14%). TP53MT were classified as ICC-defined multihit in 67 (58%) cases; karyotype in the latter was MK (58%), CK (16%), non-MK/CK (13%), or NK (13%). TP53 VAF was ≥50% in 27 (24%) patients and &lt;10% in 25 (22%). TP53MT included one (N=96) or ≥2 (N=19). MPN subtype- and stage-specific distributions for multihit TP53MT were 91% for MPN-BP, 88% MPN-AP, 44% MF-CP, and 0% ET/PV. In order to examine disease subtype- and stage-specific prognostic contribution of TP53MT, the study population was divided into 10 operational groups: 1) PV/ET non-multihit/non-MK/CK (N=8; VAF range 3-32%); 2) MF-CP non-multihit/non-MK/CK with TP53MT VAF &lt;10% (N=10); 3) MF-CP non-multihit VAF ≥10% and non-MK/CK (N=11); 4) PV/ET/MF-CP non-multihit with MK/CK (N=5); 5) MF-CP multihit/non-MK/CK (N=8); 6) MF-CP multihit and MK/CK (N=20); 7) MPN-BP/AP non-multihit/non-MK/CK (N=2); 8) MPN-BP/AP non-multihit with MK/CK (N=2); 9) MPN-BP/AP multihit/non-MK/CK (N=9); and 10) MPN-BP/AP multihit with MK/CK (N=30). The corresponding median survivals were “not reached”, 55, 42, 6, 18, 10, “not reached”, 4, 4, and 6 months (p&lt;0.01). Survival was similar between groups 1, 2, and 3 (p&gt;0.2 for all comparisons) now referred to as “PV/ET/MF-CP non-multihit/non-MK/CK (N=39)”. Survival was similarly dismal for groups 8, 9, and 10 (p values &gt; 0.3 for all comparisons) now referred to as “MPN-BP/AP with or without multihit TP53MT or MK/CK (N=43)”. Survival was also similar between groups 4, 5, and 6 (p values &gt;3 for all comparisons) now referred to as “PV/ET/MF-CP with multihit TP53MT or MK/CK (N=33)”. The three consolidated groups were subsequently compared for survival that showed a significantly worse outcome for “MPN-BP/AP with or without multihit TP53MT or MK/CK” with median survival of 4 months, compared to 12 months for “PV/ET/MF-CP with multihit TP53MT or MK/CK” (HR 2.3; 95% CI; 1.3-3.9) and 55 months for “PV/ET/MF-CP non-multihit/non-MK/CK” (10.9; 95% CI 5.3-22.4); survival in the latter two groups was also significantly different, in favor of PV/ET/MF-CP non-multihit/non-MK/CK (HR 4.8; 95% CI 2.3-10.1). Conclusions: The presence of multi-hit TP53MT or MK/CK, in MF-CP, and possibly in ET/PV, warrants their inclusion in the ICC category of “myeloid neoplasms with mutated TP53”. By contrast, non-multihit TP53MT in ET/PV/MF-CP, regardless of VAF and in the absence of MK/CK, does not appear to compromise short-term survival. The observations from the current study also suggest a prognostic hierarchy with blast percentage being the most unfavorable, followed by MK/CK and multihit TP53MT.

Background Pacritinib (PAC) is a relatively selective JAK2 vs. JAK1 inhibitor (JAKi) and is one of four FDA-approved JAKi for use in myelofibrosis (MF). PAC is indicated for MF patients with thrombocytopenia (Platelets &lt;50 x 109/L). In a previously published controlled study of MF patients with platelet count &lt;100 x 109/L (PERSIST-2), including JAKi-naïve and ruxolitinib-experienced, PAC therapy at the recommended dose of 200 mg BID was associated with a ≥35% spleen volume reduction rate of 22%; response rate was lower in ruxolitinib-experienced patients for both 200 mg BID (9.3%) and 100 mg BID (1.8%) dosing (JAMA Oncol 2018;4:652); a more recent post-hoc analysis suggested an additional benefit in anemia with 25-37% of transfusion-dependent patients achieving a ≥12-week transfusion-free period (Blood Adv 2023;7:5835). Herein, we describe our experience with the drug outside of a clinical trial setting. Methods Study patients were retrospectively recruited from Mayo Clinic (USA) databases, after approval from IRB. Diagnostic criteria were according to the International Consensus Classification (Blood 2022;140:1200). Study inclusion criteria included documentation of PAC therapy outside of a clinical trial setting. Spleen response was adjudicated by the 2013 International Working Group-European LeukemiaNet (IWG-ELN) response criteria (Blood 2013;122:1395). Anemia response was rated by the revised 2024 IWG-ELN criteria (manuscript submitted; transfusion-free period x 12 weeks and/or 12-week average increase in hemoglobin ≥1.5 g/dL). Conventional statistical methods were employed. Results A total of 60 MF patients (median age 70 years; males 62%; primary MF 63%) received PAC upfront (N=19; 32%) or after failing treatment with another JAKi (N=41; 68%), including ruxolitinib (N=39; 65%): JAK2 60%, CALR 27%, MPL 10%. Reasons for discontinuation of previous JAKi treatment included drug intolerance (41%), relapse after initial response (33%), and suboptimal response (26%). Median interval between diagnosis and treatment with PAC was 4 years (range 0-22). At PAC treatment initiation, DIPSS-plus risk distribution was high in 48%, intermediate-2 47%, and intermediate-1 (5%). Transfusion-dependent anemia (TDA; ≥3 units during 12 weeks prior to enrollment) was present in 40% of patients, platelet count &lt;50 x 109/L 25%, leukocyte count &gt;11 x 109/L 40%, spleen size &gt;15 cm 76%, constitutional symptoms 55%, complex/monosomal karyotype 27%, and mutations in SRSF2 11% or ASXL1 33%. PAC initial dose was 100 (N=41) or 200 (N=19) mg BID. Dose was increased in 44% of patients started at 100 mg BID and decreased in 55% of those started at 200 mg BID. Among 47 patients evaluable for anemia response, only one of 23 with non-TDA (2% overall and 4.3% at 200 mg BID dosing) and none of 24 with TDA responded. In evaluable patients, spleen response rate was 13% (95% CI 5.9-24.7) overall and higher in JAKi-naïve (29%; 95% CI 11.7-54.7) vs. JAKi-experienced (6%; 95% CI 1.6-19.1; p=0.04). Spleen response rate was higher in the absence of leukocytosis (21% vs. 0%; p=0.01) or complex/monosomal karyotype (17% vs. 0%; p=0.05) but similar between 100 and 200 mg BID initial dosing (p=0.9). At a median follow-up of 14 months (range 1-27), PAC was discontinued in 80% of the patients: intolerance 58%, suboptimal response 54%, transition to allogeneic stem cell transplants (ASCT) 10%. Major side effects were more frequent with 200 vs. 100 mg BID dose and included diarrhea 43%, nausea/vomitting 17%, dyspnea 25%, peripheral edema 28%, allergic reaction 13%, grade 3/4 neutropenia 22%, and grade 4 thrombocytopenia 34%. Up to the time of this writing, 17 deaths (28%), 11 (18%) ASCT, and 3 (5%) leukemic transformations were documented. In multivariable analysis, post-PAC survival was adversely affected by TDA (HR 11.9; p&lt;0.01), platelet count &lt;50 x 109/L (HR 7.4; p&lt;0.01), and SRSF2/ASXL1 mutations (HR 10.7; p&lt;0.01), all independent of ASCT, which was independently associated with longer survival (HR 9.0; p&lt;0.01). Conclusions: The observations from the current real-world study, regarding the moderate activity of PAC for reducing spleen size, are consistent with those of the aforementioned controlled clinical trial (PERSIST-2). However, despite recent suggestions of the drug's mechanistically unique erythropoietic activity, the anemia response rate seen in the current study was underwhelming.

Background Survival risk models in essential thrombocythemia (ET) include the International Prognostic Scoring System (IPSET; Blood 2012;120:1197) and the more recently described “triple-A” prognostic score that considers Age and absolute neutrophil (ANC) and lymphocyte (ALC) counts, as risk variables (AJH 2023;98:1829). Monocytosis, defined by absolute monocyte count (AMC) of ≥0.8 x 109/L, was recently reported to be associated with inferior survival in polycythemia vera (ASH 2024 abstract). The current study examined the prognostic contribution of monocytosis in ET, in the context of other clinical and genetic risk factors. Methods Study patients were recruited from Mayo Clinic (USA) databases, based on availability of information on ANC, ALC, and AMC (N=649). Diagnostic criteria were according to the International Consensus Classification (Blood 2022;140:1200). Mutations were screened by next-generation sequencing (NGS). Conventional statistical methods were employed (JMP Pro 17.0.0, SAS Institute, Cary, NC, USA) and optimal cut-points for age, ANC, ALC, and AMC were determined by Receiver Operating Characteristic (ROC) analysis. Akaike Information Criterion (AIC) and ROC plots were used to estimate predictive accuracy of risk models. Results A total of 649 patients (median age 60 years; females 65%) were informative for AMC, ANC, and ALC, with median (range) values of 0.6 x 109/L (0.2-2.5), 5.7 x 109/L (1.5-26.5), and 1.9 (0.4-5.7), respectively. At presentation, IPSET risk distribution was low in 34%, intermediate 47%, and high 19%; triple-A risk distribution was low 21%, intermediate-1 50%, intermediate-2 13%, and high 16%; driver mutation distribution was 63.8% JAK2, 24.0% CALR, 3.7% MPL, and 8.5% triple-negative; median for platelets were 728 x 109/L, hemoglobin 13.9 g/dL, and leukocytes 8.5 x 109/L ; leukocytosis (leukocytes ≥11 x 109/L) was documented in 18.8% of patients, palpable splenomegaly 7%, arterial thrombosis (AT) history 14.5%, venous thrombosis (VT) history 9.2%, and major hemorrhage 7.8%. At median follow-up of 7 years (range 0.02-31.4), 146 (22.5%) deaths, 52 (8%) fibrotic progressions, 22 (3.4%) leukemic transformations, 71 (11%) AT events, 36 (5.6%) VT events, and 64 (10%) major bleeds were recorded. In age-adjusted univariate analysis, higher AMC was significantly associated with inferior survival, with a ROC determined cutoff value of ≥0.8 x 109/L (N=154; 24%); significance was sustained (HR 2.3; p&lt;0.01) during multivariable analysis (MVA) that also identified age &gt;70 years (HR 16.6; p&lt;0.01), age 50-70 years (HR 4.3; p&lt;0.01), ANC ≥8 x 109/L (HR 1.9; p&lt;0.01), ALC &lt;1.7 x 109/L (HR 1.8; p&lt;0.01), and AT history (HR 1.6; p=0.01). A similar MVA conducted on an external cohort from the University of Florence (N=514) confirmed the significant contribution from all of these risk variables, except AT (p=0.8). An HR-based 4-variable prognostic model based on Age &gt;70 years (4 points) or 50-70 years (2 points), AMC ≥0.8 x 109/L (1 point), ANC ≥8 x 109/L (1 point), and ALC &lt;1.7 x 109/L (1 point), henceforth referred to as the AAA+A model, was subsequently developed using the Mayo Clinic cohort and validated by the Florence cohort: Low (0-1 points; N= 180; median not reached), intermediate-1 (2-3 points; N=266; median 21.6 years), intermediate-2 (4-5 points; N=151; median 12.2 years), and high (6-7 points; N=52; median 8.7 years); HR values were 2.1 for high vs. intermediate-2, 5.4 for intermediate-2 vs. intermediate-1, and 3.8 for intermediate-1 vs. low (p&lt;0.001in all instances). The 20-year survival predictive performance of AAA+A (AIC 131; AUC 0.88) was superior to that of AAA (AIC 143; AUC 0.85) and IPSET (AIC 149; AUC 0.84). In MVA that included AAA+A risk variables, AMC ≥0.8 x 109/L (p=0.04) and ALC &lt;1.7 x 109/L (p=0.06) appeared to affect leukemia-free survival and ANC ≥8 x 109/L (p=0.04) myelofibrosis-free survival. In univariate analysis, AMC ≥0.8 x 109/L was associated with AT (p=0.03) but not VT (p=0.14) history and showed borderline significance for venous (p=0.09) and arterial (p=0.07) thrombosis-free survivals; however, significance was lost during MVA. Conclusions: Monocytosis is an adverse prognostic factor in ET and its inclusion as a risk variable enhances the predictive performance of the AAA risk model and is equally simple to apply worldwide. Analyses that include mutations will be presented at meeting.