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Introduction The COVID-19 pandemic has affected the entire world. Health systems have been affected in such a way that patients with diseases other than COVID-19 have suffered serious consequences. In Latin America, the disease has emerged in a fragile system with more disparities, making our patients more vulnerable. Acute leukemia patients have a high risk of severe COVID-19 disease. Various expert recommendations have emerged with the aim of minimizing the risk of COVID-19 without affecting leukemia-related outcomes. However, multiple logistical issues tangentially associated with the pandemic have also appeared, potentially limiting the quality of management of these patients. The objective of this study was to register treatment modifications associated with the COVID-19 pandemic and its short-term consequences in Latin American countries. Methods We included patients older than 14 years, from 14 centers of 4 Latin American countries (Mexico, Peru, Guatemala and Panama), with the diagnosis of acute leukemia, who were on active treatment since the first case of COVID-19 was documented in each country. We documented their baseline characteristics and followed the patients prospectively until July 15, were data-cutoff for this pre-planned analysis was performed. The primary outcome was the incidence of COVID-19 disease and its complications. Secondary outcomes included treatment and consult modifications, and cause of death during the study period. Logistic regression was performed to determine factors associated with COVID-19 and all-cause mortality. Results We recorded the information of 635 patients: 58.1% Ph-negative ALL, 25.7% AML, 9% APL and 7.2% Ph+ALL. The median age was 35 years (14-90 years); 58.8% were consideredf high-risk patients. The majority were on CR (68.3%) receiving consolidation or maintenance therapy, while 14.5% were newly diagnosed and 17.2% with relapsed/refractory disease. The majority (91.8%) were treated in centers that were also receiving COVID-19 patients, 40.2% in centers were patients could not be electively hospitalized for leukemia treatment because of the COVID-19 pandemic. The COVID-pandemic led to treatment-modifications in 40.8% of the cases. Reasons for modifications were associated with logistical issues (22.4%), medical decisions (15.1%) or patient choice (3.3%). The most frequent modification was chemotherapy delay (17.3%) followed by regimen modification (13.4%) and dose-reductions (10.1%). (Figure 1) 83 patients (13.1%) developed COVID-19 disease, the majority mild-moderate disease (54.2%), 27.7% severe disease and 18.1% critically ill; 27.7% required mechanical ventilation and 37.7% died from COVID-19 disease, representing 4.9% of the entire cohort. We identify as risk factors for COVID-19 disease the presence of active leukemia (newly diagnosed or relapsed) (OR 3.46 [95% CI: 2.16-5.5], p On the other hand, 16.7% of patients died during period analyzed due to leukemia (57.5%), COVID-19 (29.2%) or treatment related-mortality (13.2%). Independent factors associated with mortality were AML vs. ALL (OR 1.89 [95% CI: 1.12-3.18], p=0.016), relapsed-refractory disease (OR 8.34 [95% CI: 4.83-14.41], p Discussion/Conclusions The COVID-19 pandemic led to significant modifications in the standard of care treatment of patients with acute leukemia. The incidence of COVID-19 disease in acute leukemia patients was considerable and more than a third of the patients with acute leukemia and COVID-19 disease died. Despite a short-follow up, 16.7% of the patients died and leukemia-related deaths were the most frequent. In low- and middle-income countries with fragile health systems, the collateral damage for patients with acute leukemia may be just as important as the direct consequences of COVID-19. Disclosures Alvarado: Roche: Speakers Bureau; Novartis: Speakers Bureau; Amgen: Speakers Bureau; Celgene: Speakers Bureau; Alexion: Speakers Bureau. De la Peña-Celaya:Amgen: Speakers Bureau; Janssen: Speakers Bureau; Novartis: Speakers Bureau. Perez:Roche: Speakers Bureau; Celgene: Speakers Bureau; Novartis: Speakers Bureau. Gomez-Almaguer:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

The Ph chromosome is a translocation (9;22)(q34;q11), that results in the constitutive activation of the BCR/ABL tyrosine kinase. The incidence of BCR/ABL in Acute Lymphoblastic Leukemia (ALL) increases with age, from less than 5% in younger children to 20-30% in older adults, with a peak incidence in patients aged 35-50 years. BCR/ABL1 has diverse breakpoints, in adult patients with Ph+ ALL the p190BCR/ABL transcript e1a2/e3a2 may be documented in 50-70%; p210BCR/ABL b2a2/b3a2 in 15-30% of patients and OBJETIVE. The aim of this study was identify the occurrence of fusion genes to p190 and p210 BCR-ABL rearrangements in adult and childhood patients with ALL. METHODS. We include between 2008-2015 870 patients with ALL de novo from seven different hospitals from México, the 45% (394) were childood and the rest 55% (476) were adults. All patients were studied to RT-PCR multiplex and nested in RNA for fusion transcripts 190 and p210 BCR-ABL, at diagnosis, according to the international BIOMED-1 protocol. RESULTS. From 870 patients with ALL, the most frequent subtype FAB were L2 (87%) and second L1 (13%). The immunophenotype by B-ALL was to 80%, bilineal in 5% and the rest have not data. The overall incidence to BCR-ABL in both children and adults with ALL were to 17% [147/870]. The analysis by age group were; in 476 adults with ALL, their average age was 37 years old (range 17-84 years) and their incidence of BCR-ABL positive was 20% (95/476 cases). The distributions by type of fusion transcript were 83% p190 and 17% p210; we did not observe co-expression of transcripts to BCR-ABL. In children patients the average age was 9 years old (range 0.1-16 years), the incidence of BCR-ABL was 13.2% (52/394 cases). The distributions by type of fusion transcript to BCR-ABL were p190 78.8%; p210 13.4% and their co-expression by both isoforms 8%. CONCLUSION. The 20% frequency for BCR-ABL1 in adults with ALL is concordant with others reports published, with values from 17% to 37% with predominancy of p190 (83%). In our pediatric patients group with ALL, document a frequency of 13.2% by BCR-ABL1 positive; it is higher than other populations reporting 5-10%. The distributions of fusion transcript p190 and p210 coincides with previous prevalence estimates in other countries where p190 transcript was the most frequent. But the coexpression of both isoforms [p190/p210] were 8% it has not been reported in this age group with ALL. In conclusion, we recommend to identify the BCR-ABL transcript type in every patients with ALL at diagnosis, using a RT-PCR verified method for P190/p210 and followed the patient by mesure the impact clinical and will be adjust the treatment like o plus the cytogenetic studies. Disclosures No relevant conflicts of interest to declare.

Although there have been extraordinary advances in leukemia therapy, there is still a large subset of cases in which complete remission or prolonged leukemia-free survival cannot be achieved. Some of this variability in results is thought to be related to the differences in the effect of chemotherapy drugs on different patients. In many cases, these differences may be associated with the presence of genetic alterations that produce defective drug-metabolizing enzymes, drug transporters or drug targets. One of these is the glutathione-S transferase (GST) gene, which is known to catalyze the conjugation of toxic compounds, such as aliphatic aromatic heterocyclic radicals and epoxides, among others, to glutathione. The enzymes encoded by this gene detoxify polycyclic aromatic hydrocarbons and conjugated isothiocyanates. Objective : Our aim is to evaluate the frequency of deletions in GSTT1 and GSTM1 of the GST gene in Mexican patients with de novo acute leukemia. Methods : Starting in July 2003 and up until now, have included 75 samples from as many patients diagnosed with de novo acute leukemia, regardless of age, sex, or leukemia type. After obtaining informed consent, we drew blood, purified DNA and performed PCR to look for deletions in the GST gene (variants GSTT1 and GSTM1). Results: We found GSTM1 positiveness in 54 samples (72%), of those, 24 (44.5%) were ALL and 30 (55.5%) AML. We had 18 samples (24%) positive for the GSTT1 deletion; of those, 10 (55.5%) were from patients with ALL and 8 (44.4%) from AML patients. Conclusions ; As far as we can tell this is the first report of the frequency of these genetic deletions in Mexican acute leukemia patients. Recently a Mexican group studying the possible association of GSTT1 to lung cancer found that among Mexican controls, the frequency of this deletion was around 4.5%. This result would appear to indicate, as has been done by some other authors, that regardless of the possibility of becoming a prognostic factor, at least some polymorphism of the GST gene could be related to the genesis of this disease.