Natural history of PF4 antibodies in vaccine-induced immune thrombocytopenia and thrombosis.

The COVID-19 pandemic has resulted in the rapid development of a range of vaccines against SARS-CoV-2. Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a rare but life-threatening complication of primarily adenoviral-based vaccines associated with the presence of antibodies to a PF4/polyanion neoepitope and measured by using enzyme-linked immunosorbent assays. Presented are serial anti-PF4/polyanion antibody, platelet, and D-dimer measurements in a large cohort of patients and their relation to relapse. Overall, 51% of patients using the Stago assay had persistently positive anti-PF4/polyanion levels 100 days' postdiagnosis, whereas 94% of patients monitored by using the Immucor assay remain positive. The median duration of positivity of the PF4 assay is 87 days, with 72% of patients remaining positive after a median follow-up of 105 days. The use of plasma exchange seemed to reduce anti-PF4/polyanion levels and increase platelet counts in the acute setting more rapidly than other therapies. The rate of relapse in this study was 12.6%, with all relapsed cases exhibiting persistently positive PF4 antibodies and falling platelet counts. Only one patient had extension of their thrombosis. Overall, despite the persistence of PF4 antibodies in 72% of patients, the rate of relapse was low and did not seem to result in recrudescence of the aggressive clinical picture seen at index presentation. Monitoring of these patients in the UK cohort is ongoing and will aid in definition of the natural history of this novel condition.

Effect of low-level BCR-ABL1 kinase domain mutations identified by next-generation sequencing in patients with chronic myeloid leukaemia: a population-based study.

BACKGROUND: Kinase domain mutations in BCR-ABL1 are associated with resistance to tyrosine kinase inhibitors in patients with chronic myeloid leukaemia. Next-generation sequencing (NGS) allows detection of low-level kinase domain mutations, but its relevance in clinical practice remains debated. We aimed to examine the clinical effects of low-level kinase domain mutations identified using NGS in patients with chronic myeloid leukaemia. METHODS: In this population-based study, we included consecutive patients newly diagnosed with chronic myeloid leukaemia treated with first-line tyrosine kinase inhibitors, and patients identified at the time of resistance to first-line treatment with imatinib at six institutions (teaching hospitals and district hospitals) in southeast England. We screened patients for BCR-ABL1 kinase domain mutations using NGS, irrespective of patient response to tyrosine kinase inhibitor therapy. When we detected a mutation with NGS, we retrospectively analysed all previous samples to establish the date of first occurrence and subsequent kinetics of the mutant subclone (or subclones). The primary endpoints of this study were progression-free and event-free survival at 5 years. FINDINGS: Between Feb 1, 2007, and Dec 31, 2014, we screened 121 patients with chronic myeloid leukaemia for BCR-ABL1 kinase domain mutation. 99 consecutive patients were newly diagnosed, with available sequential RNA stored. The remaining 22 patients were diagnosed between June 1, 1999, and June 30, 2006, and were screened at the time of resistance to first-line treatment with imatinib. Imatinib was the first-line treatment for 111 patients, nilotinib for seven patients, and dasatinib for three patients. We detected a kinase domain mutation in 25 (21%) of 121 patients. Low-level kinase domain mutations were first identified in 17 (68%) of 25 patients with mutation. For patients with a complete cytogenetic response, 13 (14%) of 93 patients screened had a mutation. Five (71%) of the seven patients with a clinically relevant mutation lost complete cytogenetic response compared with 15 (17%) of 86 patients without a clinically relevant mutation (80 patients without mutation and six patients with a tyrosine kinase inhibitor-sensitive mutation, p=0·0031). Patients harbouring a mutant clone had poorer 5-year progression-free survival (65·3% [95% CI 40·5-81·8] vs 86·9% [75·8-93·2]; p=0·0161) and poorer 5-year event-free survival (22·2% [CI 5·6-45·9] vs 62·0% [50·4-71·6]; p<0·0001) than did patients without a mutation. We identified a kinase domain mutation in four (10%) of 41 patients with samples available at 3 months after starting first-line tyrosine kinase inhibitor treatment; all four subsequently progressed to accelerated phase disease compared with only three (8%) of 37 without a mutation (p<0·0001). INTERPRETATION: NGS reliably and consistently detected early appearance of kinase domain mutations that would not otherwise be detected by Sanger sequencing. For the first time, to our knowledge, we report the presence of kinase domain mutations after only 3 months of therapy, which could have substantial clinical implications. NGS will allow early clinical intervention and our findings will contribute to the establishment of new recommendations on the frequency of kinase domain mutation analysis to improve patient clinical care. FUNDING: None.

Autoimmune diseases and myelodysplastic syndromes.

Immune dysregulation and altered T-cell hemostasis play important roles in the pathogenesis of myelodysplastic syndromes (MDS). Recent studies suggest an increased risk of MDS among patients with autoimmune diseases. Here, we investigated the prevalence of autoimmune diseases among MDS patients, comparing characteristics and outcomes in those with and without autoimmune diseases. From our study group of 1408 MDS patients, 391 (28%) had autoimmune disease, with hypothyroidism being the most common type, accounting for 44% (n = 171) of patients (12% among all MDS patients analyzed). Other autoimmune diseases with ≥5% prevalence included idiopathic thrombocytopenic purpura in 12% (n = 46), rheumatoid arthritis in 10% (n = 41), and psoriasis in 7% (n = 28) of patients. Autoimmune diseases were more common in female MDS patients, those with RA or RCMD WHO subtype, and those who were less dependent on red blood cell transfusion. Median overall survival (OS) was 60 months (95% CI, 50-70) for patients with autoimmune diseases versus 45 months (95% CI, 40-49) for those without (log-rank test, P = 0.006). By multivariate analysis adjusting for revised IPSS and age >60 years, autoimmune diseases were a statistically significant independent factor for OS (HR 0.78; 95% CI, 0.66-0.92; P = 0.004). The rate of acute myeloid leukemia (AML) transformation was 23% (n = 89) in MDS patients with autoimmune disease versus 30% (n = 301) in those without (P = 0.011). Patient groups did not differ in response to azacitidine or lenalidomide treatment. Autoimmune diseases are prevalent among MDS patients. MDS patients with autoimmune diseases have better OS and less AML transformation.

Successful treatment of aplastic anaemia associated with HIV infection with eltrombopag: implications for a possible immunomodulatory role.

We report the first successful treatment with the thrombopoietin receptor mimetic eltrombopag in a patient with severe aplastic anaemia (SAA) associated with HIV infection, thereby avoiding the use of standard immunosuppressive agents for treatment of SAA. Eltrombopag induced a trilineage haematological response. We also show that eltrombopag had an immunomodulatory role with a decrease in proinflammatory T helpers (Th1 and Th17 cells) with increased T-regulatory cell/T-helper ratio, thus contributing to recovery of haemopoiesis.

Allogeneic haematopoietic stem cell transplantation in myelodysplastic syndromes.

PURPOSE OF REVIEW: Allogeneic haematopoietic stem cell transplantation remains the only curative treatment for myelodysplastic syndrome. We highlight the various issues to consider in the pretransplant, transplant and posttransplant periods with emphasis on the management of relapse following transplant. RECENT FINDINGS: Cytogenetic and molecular characteristics are becoming more important in predicting transplant outcome. Hypomethylating agents are effective in the pretransplant setting to reduce disease burden. Haploidentical and umbilical cord blood donations may be valid transplant options for patients without human leukocyte antigen-identical sibling or match unrelated donor options. A preemptive management approach to patients at high risk of relapse is more effective. Adjusting the timing and dose of donor lymphocyte infusion reduces the risk of graft-versus-host disease without jeopardizing the graft-versus-leukaemia effect of donor lymphocyte infusion. SUMMARY: Allogeneic haematopoietic stem cell transplantation is curative in up to 40% of myelodysplastic syndrome patients. Appropriate patient selection, modification of conditioning regimes and donor selection should be considered carefully. A preemptive approach for the management of patients at high risk of relapse should be employed following transplant, with the use of immune modulating therapies such as donor lymphocyte infusion and azacitidine.