Momelotinib is a highly potent inhibitor of FLT3-mutant AML

Kinase activating mutation in FLT3 is the most frequent genetic lesion associated with poor prognosis in acute myeloid leukemia (AML). Therapeutic response to FLT3 tyrosine kinase inhibitor (TKI) therapy is dismal, and many patients relapse even after allogenic stem cell transplantation. Despite the introduction of more selective FLT3 inhibitors, remissions are short-lived, and patients show progressive disease after an initial response. Acquisition of resistance-conferring genetic mutations and growth factor signaling are two principal mechanisms that drive relapse. FLT3 inhibitors targeting both escape mechanisms could lead to a more profound and lasting clinical responses. Here we show that the JAK2 inhibitor, momelotinib, is an equipotent type-1 FLT3 inhibitor. Momelotinib showed potent inhibitory activity on both mouse and human cells expressing FLT3-ITD, including clinically relevant resistant mutations within the activation loop at residues, D835, D839, and Y842. Additionally, momelotinib efficiently suppressed the resistance mediated by FLT3 ligand (FL) and hematopoietic cytokine activated JAK2 signaling. Interestingly, unlike gilteritinib, momelotinib inhibits the expression of MYC in leukemic cells. Consequently, concomitant inhibition of FLT3 and downregulation of MYC by momelotinib treatment showed better efficacy in suppressing the leukemia in a preclinical murine model of AML. Altogether, these data provide evidence that momelotinib is an effective type-1 dual JAK2/FLT3 inhibitor and may offer an alternative to gilteritinib. Its ability to impede the resistance conferred by growth factor signaling and activation loop mutants suggests that momelotinib treatment could provide a deeper and durable response; thus, warrants its clinical evaluation.

The 15 Year Long-Term Survival of Patients with Chronic Myeloid Leukaemia from 35 Regions of Russian Federation: A Follow up of a Multicenter Observation Study Eutos Osp Initiated By European Leukemia NET

The results of long-term follow-up of patients (pts) with chronic myeloid leukemia (CML) do not lose their importance. Data from routine clinical practice are of particular interest. The use of 1 st (imatinib, IM) and 2nd generation TKI (2G TKI) led to a significant increase in survival, so the probability of death associated with CML could be significantly lower than the probability of death due to common causes of death other than CML. To analyze the overall survival (OS) and causes of mortality in CML pts treated in routine clinical practice in Russian Federation for a long period (>15 years) of time. The long-term follow-up data of the Russian part of the European LeukemiaNet (ELN) OSP EUTOS multicenter observational study were evaluated. The analyzed cohort consisted of 678 Ph/BCR-ABL-positive CML pts from 35 regions of Russia diagnosed in 2002-2006 with IM therapy initiation ≤6 months (mo) after diagnosis. Median (Me) age was 47(range 18-81) years (y), 47% males. Chronic phase, accelerated phase and blast crisis at diagnosis was in 631 (93%), 41(6%) and 6(1%) pts, respectively. The annual number of newly diagnosed pts was as follows: 2002 - 15 pts, 2003 - 38 pts, 2004 - 46 pts, 2005 - 206 pts, 2006 - 302 pts. The last update for 209 pts was done in Jun. 2021; last contact for 100 pts - in 2020, for 39pts - in 2019, for the other - before 2018. The date of the last contact/death could not be established for 14 pts. Statistical analysis included 661 pts, the OS was evaluated by Kaplan-Mayer method using the SAS 9.4 package. In total, 331 (50%) pts of the analyzed cohort were alive with the Me follow-up of 180 (range 2-232) mo or 15 y (range 2 mo-19,3 y). All pts started therapy with IM with 25% switched to 2G TKI in subsequent therapy lines. In total, 218 (66%) pts achieved MR4, 183 (55%) pts got MMR; 46 (21%) of these pts with deep molecular response (DMR) were observed in hematology centers of Moscow. The 15-y OS in the total cohort was 63% (CI 59-70%)(fig.1). The OS by age groups was as follows: 18-40yy-75% (CI 73-82%), 40-60yy- 63% (CI 59-70%), 60-80yy- 37% (CI 30-45%). The most complete information was provided by Moscow centers (2 centers, 113 pts). The 15-y OS of pts receiving treatment in Moscow was significantly higher vs pts from other regions (32 centers, 548 pts): 75% vs 60%, p=0,0030 (fig.2). The mortality in the whole cohort of 661 pts was 35% (233 pts). Of these 233 pts, 112(48%) pts deaths were due to CML progression to AP or BP (including non-compliant cases); 3pts (1,5%) died after allogenic stem cell transplantation (infection complications); the cause of death was unknown in 50 (21,5%) pts. The highest death rate from CML progression was at 4-9 y of follow-up. Deaths caused by concomitant diseases were in 68 (29%) pts: coronary artery disease/myocardial infarction/heart failure in 42 (62%) of 68 pts, acute ischemic stroke in 10 (15%) pts, second malignancies (Cr- cancer) in 10 (15%) pts (lung tumor, metastatic esophageal Cr, stomach Cr, brain tumor, sigmoid colon Cr, rectal colon Cr, melanoma, renal Cr, breast tumor, other hematological malignancies), accidents - 1 pt, liver cirrhosis - 2 pts, in 2 cases - respiratory virus infections complicated with pneumonia, 1 pt died due to Covid-19. Conclusions. The long-term follow-up of the multicenter study EUTOS OSP in 35 regions of Russian Federation allows not only to characterize the 15-y OS in CML pts but also provides the long-term outlook of the routine clinical practice. Probably, better OS of CML patients receiving treatment in Moscow (2 centers) may be related to organizational issues of interaction with the federal center, better monitoring and timely switching to 2G TKI therapy. The organization and support of multicenter studies may improve the situation with the treatment of diseases of the blood system. Figure 1 Figure 1. Disclosures Chelysheva: Novartis Pharma: Speakers Bureau; Pfizer: Speakers Bureau; Pharmstandart: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Vinogradova: Pharmstandart: Speakers Bureau; Novartis Pharma: Speakers Bureau; Pfizer: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Lomaia: Novartis: Honoraria; Pfizer: Honoraria; BMS: Honoraria; Pharmstandard: Honoraria. Voloshin: Abbvie: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Astra Zeneca: Consultancy, Speakers Bureau; Pfizer: Consultancy; Biacad: Consultancy, Speakers Bureau. Turkina: Pharmstandart: Speakers Bureau; Pfizer: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau; Novartis Pharma: Speakers Bureau.

D1S111 and 33.4 Polymorphism as a Tool of Genetic Identity among Egyptians

Background The variable number tandem repeats (VNTR) are highly polymorphic markers. Due to their high polymorphic content, VNTR constitute useful tools in population genetic studies in understanding population and ethnic migrations throughout history. They also constitute preferred systems for DNA “fingerprinting”, criminal and forensic examinations and paternity testing, evaluating hematopoietic chimerism and in determining the origin of leukemic cells in patients with recurrent disease after BMT. Aim of the Work To standardize PCR protocols of 2 VNTR loci (D1S111/33.6 and 33.4) in order to detect allelic polymorphism among Egyptians as a tool in following up the chimeric status after allogenic stem cell transplantation. Patients and Methods The current study was conducted at Clinical Pathology Department of Ain Shams University Hospital between January 2018 and December 2019, a total of 130 subjects [65 pairs (allogenic stem cell transplantation donors and their recipients)] were included. D1S111/33.6 and 33.4 VNTR loci were evaluated in every subject by PCR technique to study their relative distribution and number of informative alleles detected in order to be used in chimerism follow up and population studies. Results Five alleles were found at D1S111/33.6 in 130 subjects with molecular weight ranging from 364 to 993 bp, frequency of homozygous alleles were 30.8% and it was 69.2% for heterozygous, 90 out of the total 130 subjects were heterozygous for 33.6, that means that the heterozygosity index for D1S111/33.6 is 69.2%, from the 65 pairs tested 31 pair were informative or discriminative with discriminative power 47.69%. For 33.4 we tried many PCR programs but no bands were detected at all. Conclusion D1S111/33.6 VNTR polymorphism is a dependable cost effective method in following up of allogenic stem cell transplantation recipients.

DNAM-1/CD226 is functionally expressed on acute myeloid leukemia (AML) cells and is associated with favorable prognosis

DNAM-1 is reportedly expressed on cytotoxic T and NK cells and, upon interaction with its ligands CD112 and CD155, plays an important role in tumor immunosurveillance. It has also been reported to be functionally expressed by myeloid cells, but expression and function on malignant cells of the myeloid lineage have not been studied so far. Here we analyzed expression of DNAM-1 in leukemic cells of acute myeloid leukemia (AML) patients. We found substantial levels of DNAM-1 to be expressed on leukemic blasts in 48 of 62 (> 75%) patients. Interaction of DNAM-1 with its ligands CD112 and CD155 induced release of the immunomodulatory cytokines IL-6, IL-8 IL-10 and TNF-α by AML cells and DNAM-1 expression correlated with a more differentiated phenotype. Multivariate analysis did not show any association of DNAM-1 positivity with established risk factors, but expression was significantly associated with clinical disease course: patients with high DNAM-1 surface levels had significantly longer progression-free and overall survival compared to DNAM-1low patients, independently whether patients had undergone allogenic stem cell transplantation or not. Together, our findings unravel a functional role of DNAM-1 in AML pathophysiology and identify DNAM-1 as a potential novel prognostic maker in AML.

Corneal Epithelial Stem Cells–Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.

Acute polymyositis presenting as chronic graft-versus-host disease: A systemic review.

e19025 Background: Chronic graft-versus-host disease (cGvHD) remains a significant complication of allogenic hematopoietic stem cell transplantation (allo-HSCT), with an estimated incidence of over 50%. Commonly targeted organs are skin, eyes, mouth, gastrointestinal tract, and liver. Muscular involvement and presentation as acute polymyositis (APM) remains a rare manifestation of cGvHD. We present a systemic review of APM associated with cGvHD to summarize current evidence regarding epidemiology, clinical presentation, diagnosis, treatment, and prognosis. Methods: A systemic review was conducting following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We screened 97 articles from 3 databases (PubMed, Embase, and Cochrane) using the MeSH terms and keywords for “Allogenic stem cell transplantation,” “Chronic graft-versus-host disease,” “Polymyositis” and “Myositis” from the date of inception to Jan 2021. After excluding duplicate, review and non-relevant articles, we included 36 studies (3 retrospective, others case series/reports) reporting APM associated with cGvHD after allo-HSCT. Results: We identified 72 patients, presented with APM associated with cGvHD after allo-HSCT. It involves cases of all ages, with male predominance. The onset of APM ranges as early as 100 days to 5 years, with a median range of 1.6 years post-allo-HSCT. Over half (59%) of patients had prior acute GvHD. Majority (85%) of cases presented with myalgia and progressive bilateral proximal muscle weakness with elevated Creatine phosphokinase (CPK) and/or Aldolase. Isolated presentation of APM without other manifestations of GvHD was rare, and concurrent skin involvement was present in 42% cases. Steroids remain the mainstay of treatment, achieving complete treatment response in up to 78% of cases. In some refractory cases, Rituximab has also been effective. Conclusions: APM can present as a sole manifestation of cGvHD with an estimated incidence of up to 3.4%. Diagnosis can be challenging as it can mimic idiopathic polymyositis. Radiologically targeted muscle biopsy showing characteristic myonecrosis remains the gold standard for diagnosis. Most (90%) cases respond to steroids and immunosuppression agents. Nevertheless, refractory cases remain challenging to treat and can cause significant morbidity and mortality. Characteristics of APM in 3 cohorts of allo-HSCT patients.[Table: see text]

Allogenic Stem Cell Transplantation Abrogates Negative Impact on Outcome of AML Patients with KMT2A Partial Tandem Duplication

Recently, a new subset of acute myeloid leukemia (AML) presenting a direct partial tandem duplication (PTD) of the KMT2A gene was described. The consequences of this alteration in terms of outcome and response to treatment remain unclear. We analyzed retrospectively a cohort of KMT2A-PTD-mutated patients with newly diagnosed AML. With a median follow-up of 3.6 years, the median overall survival was 12.1 months. KMT2A-PTD-mutated patients were highly enriched in mutations affecting epigenetic actors and the RTK/RAS signaling pathway. Integrating KMT2A-PTD in ELN classification abrogates its predictive value on survival suggesting that this mutation may overcome other genomic marker effects. In patients receiving intensive chemotherapy, hematopoietic stem cell transplantation (HSCT) significantly improved the outcome compared to non-transplanted patients. In the multivariate analysis, only HSCT at any time in complete remission (HR = 2.35; p = 0.034) and FLT3-ITD status (HR = 0.29; p = 0.014) were independent variables associated with overall survival, whereas age was not. In conclusion, our results emphasize that KMT2A-PTD should be considered as a potential adverse prognostic factor. However, as KMT2A-PTD-mutated patients are usually considered an intermediate risk group, upfront HSCT should be considered in first CR due to the high relapse rate observed in this subset of patients.

Sarcopenia Screening Allows Identifying High-Risk Patients for Allogenic Stem Cell Transplantation

Allogenic stem cell transplantation (aSCT) is the only potentially curative treatment for high-risk hematological diseases. Despite advancements in supportive measures, aSCT outcome is still affected by considerable transplant-related mortality. We implemented a new sarcopenia assessment prior to aSCT to evaluate its predictive capability for all-cause and non-relapse mortality. Therefore all patients initially scheduled for aSCT within a 25-month period were screened during pre-transplantation-routine for muscle mass, grip strength, and aerobic capacity (AC) by measuring peak oxygen uptake (VO2peak). Patients were assigned to one of five groups adapted according current sarcopenia guidelines. Primary endpoints were all-cause and non-relapse mortality within a follow up time of up to 12 months. A total of 178 patients were included and rated as normal (n = 48), impaired aerobic capacity (n = 56), pre-sarcopenic (n = 26), sarcopenic (n = 27), and severe sarcopenic (n = 22) without significant age-differences between groups. Patients presenting with sarcopenia showed a significant three-fold increase in all-cause and non-relapse mortality compared to patients with normal screening results. AC showed to be the strongest single predictor with a more than two-fold increase of mortality for low AC. We conclude that risk stratification based on combination of muscle mass, grip strength, and AC allowed identifying a subgroup with increased risk for complications in patients undergoing aSCT.

Hemorrhagic cystitis: A successful outcome for a challenging complication in stem cell transplant

Hemorrhagic cystitis (HC) secondary to BK polyomavirus (BKPyV) is a frequent complication related to allogenic stem cell transplantation. With an important morbidity and mortality, this disease doesn’t have a stablished standard treatment or prophylaxis strategies. At this moment, the supportive therapies approved to treat included hyperhydration, forced diuresis and transfusion support. Cidofovir is a nucleotide analog of deoxycytidine monophosphate against DNA viruses and it has been described for the treatment of BKPyV-HC, but at this moment, is not a front-line therapy. We report a successful case after the use of Cidofovir without Probenecid. No adverse effect was developed under the treatment, and after 4 weeks of treatment, the patient achieved an excellent response.