Introduction: Peripheral T cell lymphoma (PTCL) is a very heterogenous disease and corresponds to approximately 15% of all non-Hodgkin lymphoma cases. PTCL is divided into several subtypes, however, PTCL not otherwise specified (PTCL-NOS) is the most frequent, with a proportion of 26% of all PTCL cases. There is a lack of demographic and clinical data about PTCL-NOS in middle- and low-income countries, where patients' access to early diagnosis and otherwise standard care might be suboptimal. The objective of this study is to describe the population of PTCL-NOS patients in Latin America, specifically from the countries conforming the "Grupo Latinoamericano de Linfomas" (GELL), in order to better understand clinical behavior and find possible prognostic factors that might prognosticate overall survival (OS). We specifically evaluated the neutrophil/lymphocyte ratio (NLR) and serum albumin as potential prognostic factors. Methods: An observational, retrospective and analytical study was conducted during the period from January 2000 through January 2018. A total of 200 Latin American patients with a pathological diagnosis of PTCL-NOS were included. Clinical data were gathered from clinical records. NLR ≥4 and serum albumin ≤3.5 g/dl were considered adverse prognostic factors. Median Overall Survival (mOS) and 5-year Overall Survival (5y-OS) rates were estimated using the Kaplan-Meier method. Univariate and multivariate Cox proportional-hazard regression analyses were performed to identify adverse prognostic factors for OS. Data were analyzed and interpreted using STATA 15. Results: A total of 200 patients with a diagnosis of PTCL-NOS were included. 50% of patients were ≥60 years, 57% were male, 50% had ECOG ≥2, 40% had elevated serum Lactate Dehydrogenase (LDH) level, 70% showed stage III/IV disease, bone marrow involvement was present in 37% of patients, B symptoms in 65%, 33% presented with hemoglobin levels <10 g/dL. The International Prognostic Index (IPI) score was high-intermediate in 33% and high in 14% of cases. The Prognostic Index for PTCL-U (PIT) risk score was high-intermediate in 32% and high in 26% of cases. Serum albumin <3.5 mg/dl was seen in 58%, and NLR ≥4 in 37% of patients. Median OS (mOS) for the entire cohort was 0.83 years (95% CI 0.58-1.75) and 5-year OS rate was 31% (95% CI 23-40%). Patients with serum albumin levels <3.5 g/dL had mOS of 0.42 years (95% CI 0.25-0.75) and 5-year OS rate of 20% (95% CI 9-33%), while patients with albumin ≥3.5 g/dL had mOS of 5.1 years (95% CI 0.83-not reached) and 5-year OS rate of 51% (95% CI 36-65%) (log-rank p<0.001). The mOS for NLR <4 was 1.67 years (95% CI 0.75-4.92) with 5-year OS rate of 37% (95% CI 25-48%) while for NLR ≥4, the mOS was 0.58 years (95% CI 0.25-1.00) and 5-year OS rate was 23% (95% CI 12-36%) (log-rank p=0.02). Cox proportional Hazard regression multivariate analyses found serum albumin <3.5 g/dL (HR 1.83, 95% CI 1.10-3.05; p=0.02) and ECOG ≥2 (HR 1.95, 95% CI 1.15-3.30; p=0,01) were associated with a worse OS. Serum albumin remained an adverse prognostic factor for OS after adjustment for the IPI and the PIT scores (HR 1.66, 95% CI 1.01-2.75; p=0.047, and HR 1.70, 95% CI 1.03-2.80; p=0.038, respectively). Conclusion: This multi-institutional Latin American study showed that serum albumin level <3.5 g/dL was an adverse prognostic factor for OS, independent from the IPI and the PIT scores, in Latin American patients with a diagnosis of PTCL-NOS. The survival rates of Latin American patients with PTCL-NOS appear lower than in developed countries. Disclosures M: Merck-Sharp-Dome: Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Roche-Mexico: Consultancy, Speakers Bureau. Peña:Novartis: Other: Congress inscription and flights; Tecnofarma: Other: Congress inscription and flights; Roche: Other: Congress inscription and flights; Biotoscana: Other: Congress inscription and flights; Janssen: Other: Congress inscription and flights; Pfizer: Membership on an entity's Board of Directors or advisory committees. Paredes:Tecnofarma: Honoraria. Rojas:ROCHE: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; ABBVIE: Membership on an entity's Board of Directors or advisory committees. Abello:Takeda: Other: Participation in advisory board meeting. Castillo:Abbvie: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Beigene: Consultancy, Research Funding; TG Therapeutics: Research Funding.

INTRODUCTION: Adult T-cell leukemia/lymphoma (ATLL) is a mature peripheral T-cell neoplasm caused by the Human T-cell Leukemia Virus Type 1 (HTLV-1). HTLV-1 infects up to 10 million people worldwide and is most endemic in Southwestern Japan, the Caribbean basin, South America, and Western Africa. In Latin America (LA), Peru and Brazil have the highest prevalence of HTLV-1-related diseases, however, data on ATLL in other LA countries is scarce. ATLL carries a dismal prognosis and is essentially incurable by conventional drugs. We describe the epidemiology, clinical features, treatment, and disease outcome of ATLL encountered in 11 countries in LA. METHODS: We retrospectively analyzed patients (pts) diagnosed with ATLL between January 1995 and December 2019. ATLL cases were classified according to the Shimoyama criteria into acute (A), lymphomatous (L), chronic (C) and smoldering (S). Treatment approaches used as first-line therapy were: 1) chemotherapy alone; 2) combined chemotherapy with zidovudine/interferon-alpha (AZT-IFN); and 3) AZT-IFN alone, as previously done with Miami cohort (Malpica and Ramos et al. Blood Advances 2018). Treatment response was assessed according to Tsukasaki et al. (JCO 2009) criteria. To be classified as complete response (CR), partial response and stable disease, these had to persist for a period of at least 4 weeks. Survival curves were estimated using the Kaplan-Meier method and Log rank test. RESULTS: A total of 253 pts with ATLL were identified. Two hundred twenty six pts (L=122, A=73, C=26, S=5) had sufficient data for analysis. Demographic and clinical features are shown in Figure 1 and Table 1. Median age at diagnosis was 57 years, with a female predominance in A (58%) and S (100%) types. Most ATLL pts were from Peru (n=159, 63%) followed by Chile (n=44, 17%), Argentina (n=20, 8%) and Colombia (n=17, 7%). B symptoms were high present in A, L and C types (73%, 72%, 58% vs. 8% S type, respectively, p=0.011). Hypercalcemia was highly associated with A type (57% vs. L 27%, p=0.014). The PIT score yielded to a more aggressive risk classification compared to the IPI score (high-risk: 55% vs. 29%, respectively, p&lt;0.001). Strongyloidiasis (n=5) and pneumocystis jirovecii pneumonia (n=5) were the most commonly observed co-infections at diagnosis. Commonly affected extranodal sites other than bone marrow in all subtypes were skin 25% (n=63) and liver 9% (n=24). The therapy approach used during the first 2 therapy evaluations are summarized in Table 2. The median survival (MS) times were 4.3 months, 7.9 months, 21.1 months, and not reached for A, L, C and S form, with 4-year survival of 8%, 22%, 40% and 80%, respectively (Figure 2). First-line AZT-IFN resulted in overall response (OR) rate of 63% (CR 24%) for A (n=8) and 75% (CR 50%) for L (n=8), respectively (Table 3). The OR rates after first-line multi-agent chemotherapy alone for A vs. L were 21% (CR 8%) and 41% (CR 29%), respectively (Table 3). The most commonly used regimens were CHOP/CHOP-like (n=117, 59%) and CHOEP (n=40, 20%) regimens with OR rates of 29% (CR 12%) and 60% (CR 42%), respectively (Table 3). Progression-free survival (PFS) rates in pts with aggressive ATLL who achieved CR after chemotherapy vs. AZT-IFN (alone or in combination with chemotherapy) were 2.8 months vs. 30.4 months for A (n=8) type and 67.1 months vs. 17.7 months for L (n=30) type, respectively (Figure 3). Only 2 pts with L type underwent allogeneic hematopoietic stem cell transplant (allo-HSCT) with PFS of 12 and 17 months (Table 4). CONCLUSION: ATLL continues to carry a dismal outcome with conventional therapies thus urging the development of novel approaches. Our study found that Latin American ATLL variant presents at a younger age, has a female predominance, high incidence of L type, low incidence of indolent types and lower survival rates, suggesting that Latin American ATLL variant presents earlier and more aggressively than in Japanese pts. AZT-IFN produced durable responses in A type patients who achieved CR as compared to chemotherapy alone. Chemotherapy responses were more durable in L types who achieved CR as compared to A type. In conclusion, in the management of aggressive ATLL, chemotherapy remains the preferred choice for L type (with consideration of allo-HSCT upfront), while AZT-IFN is a good option to attempt for A type upfront. Figure Disclosures Peña: Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; BindingSite: Research Funding. Idrobo:Amgen: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Tecnofarma: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau. Altamirano:Hospital Nacional Guillermo Almenara Irigoyen: Other: Servicio de Hematologia. Perini:Abbvie: Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Takeda: Honoraria. Castillo:Janssen: Consultancy, Research Funding; Abbvie: Research Funding; TG Therapeutics: Research Funding; Kymera: Consultancy; Pharmacyclics: Consultancy, Research Funding; Beigene: Consultancy, Research Funding. Ramos:NIH: Research Funding. Villela:Roche: Other: advisory board, Speakers Bureau; amgen: Speakers Bureau.

lesion and 2 had multiple lesions. None had active extracranial disease. Median pre-SRT Karnofsky Performance Status (KPS) was 60 (range 50 − 90). All 7 patients completed SRT and received concurrent and adjuvant ICI therapy. Median follow-up after completion of SRT was 9.1 months. Acute toxicities of SRT and ICI therapy were minimal, including fatigue (3 patients), diarrhea (2), and adrenal insufficiency requiring oral steroids (1). Five patients (71.4%) achieved symptomatic improvement after SRT including 2 patients (28.5%) with a clinical complete response (CR). Median post-SRT KPS was 70 (range: 60 − 100). Six patients had followup imaging, and all had an objective response including 3 (50%) with a radiographic CR. The median time to best radiographic response was 2.0 months (range 0.3 − 3.7 months), and all treated lesions remained controlled on all subsequent imaging. Three patients (42.9%) experienced outof-field intracranial recurrence. Median PFS was 7.7 months (95% CI: 4.0 − 11.4 months) and median OS was 12.6 months (95% CI: 7.5 − 12.7 months) post-SRT. Conclusion: Among patients with relapsed or refractory CNSL, SRT + ICI appears to be well tolerated and offers excellent symptomatic and radiographic local control. Further studies are needed to identify appropriate candidates for salvage SRT + ICI, and to evaluate the clinical efficacy and neurocognitive impact of this approach.

Background : Adult T-cell leukemia/lymphoma (ATLL) is an aggressive, peripheral T-cell neoplasm associated with the human T-cell leukemia virus type 1 (HTLV-1). HTLV-1 infects up to 10 million people worldwide and is most endemic in Southwestern Japan, the Caribbean basin, South America and Western Africa. In Latin America, highest prevalence is found in Haiti, Jamaica, Dominican Republic, Brazil and Peru. ATLL has a poor prognosis, with shorter overall survival (OS) relative to other peripheral T-cell lymphomas. Although current prognostic models require extensive radiologic and laboratory investigations, oftentimes they are not readily available in most Latin American countries, hence, a simple prognostic model is useful. We aim to identify and then validate a simple clinical prognostic model for ATLL in the Latin American population by analyzing clinical parameters and only laboratory tests that are widely available across Latin American countries. Patients and Methods : We retrospectively analyzed patients (pts) diagnosed with ATLL between January 1987 and December 2018. Aggressive ATLL cases were classified according to the Shimoyama criteria into acute (A) and lymphomatous (L). Cox regression modeling was performed on several clinical and laboratory parameters in two independent cohorts: first, a learning cohort (LC) of ATLL pts diagnosed and managed at two tertiary hospitals in Chile and Peru, and then a cohort of ATLL pts from a tertiary hospital in Miami was used to validate the model (validation cohort, VC). OS curves were estimated using the Kaplan-Meier method and compared using the log-rank test. Univariate and multivariate Cox proportional-hazard regression models were fitted. Results : A total of 149 pts (A=55, L=94) in the LC, and 101 pts (A=58, L=43) in the VC were identified, with 101 and 94 pts receiving therapy in each cohort, respectively. Clinical features are shown in Table 1. In both cohorts, there was a young (<60 years, LC=51%, VC=64%), and female predominance (LC=52%, VC=61%). Pts in the LC had a better performance status compared to the VC (ECOG ≥2, LC=50% vs. VC=76%). Pts in the VC had advanced stages of disease (stage III/IV, LC=88% vs. VC=97%), and ≥1 extranodal involvement (LC=17% vs. VC=76%) compared to the LC. High LDH, low serum albumin (<3.5 g/dL), bone marrow involvement and anemia (hemoglobin <10 g/dL) were no different in both cohorts. The calculated International Prognostic Index (IPI) and Prognostic Index for T-cell lymphoma (PTI) scores are presented in Table 1. Most pts in the VC had high risk IPI and PIT scores (High risk: IPI LC=21% vs. VC=62%; PIT LC=38% vs. VC=51%) compared to the LC that had more low and low/intermediate IPI and PIT scores (Low risk: IPI LC=13% vs. VC=0%; PIT LC=5% vs. VC=0%; Low/intermediate risk: IPI LC=26% vs. VC=7%; PIT LC=23% vs. VC=16%). The median OS was 6 and 8.4 months in the LC and VC, respectively (Figure 1). In the univariate and multivariate analysis, ECOG ≥2 and serum albumin <3.5 g/dL were both associated with a worse OS (Table 2). When adjusted to IPI and PIT scores, serum albumin <3.5 g/dL was a negative prognostic factor, independent of IPI score, and a trend in PIT score, in the LC (adjusted for IPI: HR 1.71, 95% CI 1.06-2.75; p=0.03 / PIT: HR 1.56, 95% CI 0.95-2.56; p=0.07), but independent prognostic factor from both, IPI and PIT scores, in the VC (adjusted for IPI: HR 2.45, 95% CI 1.41-4.24; p=0.001 / PIT: HR 2.43, 95% CI 1.44-4.08; p=0.001) (Figure 2). Comparable results were found when investigating by ATLL subtype, with results trending towards significance for OS, IPI and PIT scores in the LC, but then validated in the VC (Figure 3). Conclusions : To the best of our knowledge, this is the largest retrospective study evaluating the clinical features of HTLV-1 related ATLL and impact on disease outcome in Latin America. We have validated a simple prognostic model in pts with aggressive ATLL. Our results suggest that a serum albumin level of less than 3.5 g/dL is a reliable, and independent prognostic factor for survival in aggressive ATLL. This prognostic model could be used to complement or modify existing and widely used international prognostic indexes for lymphoma. This simple paradigm could be useful in validating treatment outcomes after chemotherapy or highly needed new approaches for ATLL in prospective studies, particularly in developing countries where the absence of sophisticated laboratory and imaging tests hinder treatment decisions. Disclosures Peña: Novartis: Other: Congress inscription and flights; Tecnofarma: Other: Congress inscription and flights; Roche: Other: Congress inscription and flights; Biotoscana: Other: Congress inscription and flights; Janssen: Other: Congress inscription and flights; Pfizer: Membership on an entity's Board of Directors or advisory committees. Rojas:Pfizer: Membership on an entity's Board of Directors or advisory committees; ABBVIE: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; ROCHE: Membership on an entity's Board of Directors or advisory committees. Paredes:Tecnofarma: Honoraria. Abello:Takeda: Other: Participation in advisory board meeting. M:Merck-Sharp-Dome: Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Roche-Mexico: Consultancy, Speakers Bureau.

Background : Rituximab (RTX) is approved for various malignant hematologic and rheumatologic disorders. A noteworthy side effect, late-onset neutropenia, has been reported in patients (pts) treated for hematologic malignancies, often in combination therapies of RTX and chemotherapy with an incidence of 3% to 27%. Conversely, the lack of prospective data and the off-label use of RTX in non-malignant immune-mediated hematologic diseases (NMIHD) limits the availability of evidence on the rate, severity and time course of neutropenia on this patient population, particularly in RTX monotherapy. The present study was performed to determine the frequency, severity, and time course of development and resolution of neutropenia in NMIHD pts treated with RTX, with the goal of providing evidence for clinicians on the safety and potential implications of RTX use in this patient population. Methods : We retrospectively analyzed patients diagnosed with autoimmune hemolytic anemia (AIHA), acquired coagulation factor deficiency (ACFD), thrombotic thrombocytopenic purpura (TTP), immune thrombocytopenic purpura (ITP), and antiphospholipid syndrome (APS) between January 2013 and October 2017. Patients with a minimum of 1 laboratory visit every 8 weeks with 1-year of follow-up were included. Date of initial and last RTX infusion, RTX dosing and number of doses, and pre-treatment absolute neutrophil count (ANC) were obtained. ANCs were reviewed from first RTX infusion to at least 12 months from last infusion. For those pts who developed neutropenia, ANC nadir and date when ANC was 1 to 1.5 (mild), 0.5 to &lt;1 (moderate), and &lt;0.5 ˣ 103 cells/µL (severe neutropenia) was recorded. The time to recovery from neutropenia was determined from the time of first neutropenia occurrence to an ANC&gt;1.5. Episodes of febrile neutropenia (FN), hospitalization, infection, and use of granulocyte-colony stimulating factor (GCSF) were also obtained. Kaplan-Meier estimators, and Log-rank Tests were applied to compare between groups. Results : 197 patients (ITP=94, TTP=34, AIHA=34, ACFD=22, APS=13) treated with RTX monotherapy (73%), or in combination with other immunosuppressant were included. Clinical features, treatment characteristics and outcomes are summarized in the table. The median age at diagnosis was 51 years (58% female) with a median ANC prior to RTX initiation of 5.6 ˣ 103 cells/µL. Most pts received RTX at 375 mg/m2 in 4 doses (83%). The 1-year estimated probability of developing neutropenia (ANC&lt;1.5) was 18% (Figure 1). Of those who developed neutropenia, the median ANC nadir and time to neutropenia from initial RTX infusion was 1.2 ˣ 103 cells/µL and 4.4 months, respectively. Development of neutropenia was not statistically different by gender, age, hematologic disease type, or RTX dosing. However, RTX given for ≥ 4 doses (p=0.04), or in combination with other immunosuppressant different than steroids (p&lt;0.01) were significantly associated. Severe neutropenia was frequent in pts receiving RTX in combination with other immunosuppressant (36% versus 2%) with longer time to recovery from first neutropenia occurrence to an ANC&gt;1.5 (2.5 versus 1.1 months) (Figure 2) compared to pts receiving RTX alone or with steroids. No episodes of FN were reported, 3 pts were hospitalized for neutropenia workup, and 2 pts had documented infections (pneumonia and cellulitis) with uncomplicated clinical course. One pt, treated with 6-mercaptopurine, received GCSF. Conclusions : To the best of our knowledge, this is the first study reporting on the incidence, degree and time-course of development of neutropenia in patients treated with RTX for different NMIHD. Our analysis demonstrates an 18% rate of neutropenia at 1 year, mostly mild neutropenia. Conversely, RTX in combination with other immunosuppressant, as opposed to RTX alone or with steroids, represented a significant risk factor for the development of neutropenia, especially severe neutropenia with longer time to ANC recovery. The rate of hospitalizations, infections and the use of GCSF was low, even in severe neutropenia cases. In conclusion, development of neutropenia in pts treated with RTX for NMIHD is an expected but relatively benign side effect. Neutropenia is more frequent if RTX is given with other immunosuppressant other than steroids, and when the number of doses of RTX given are higher. Disclosures No relevant conflicts of interest to declare.