Day, Jonathan R

Abstract Introduction: Adult T-cell leukemia/lymphoma (ATLL) is a rare blood disorder associated with human T-cell leukemia virus type 1 (HTLV-1) infection. It is generally categorized into four subtypes: smoldering, chronic, lymphoma, and acute. Given the heterogeneity of these subtypes, there is a significant difference in outcomes. Robust and contemporary epidemiological data are lacking for this rare disorder. We present a retrospective cohort study of patients with ATLL, utilizing the National Cancer Database (NCDB) to better characterize the epidemiology and survival trends in the United States. Methods: This is a retrospective cohort study using the NCDB to identify ATLL cases diagnosed from 2004-2020. Descriptive statistics summarized baseline characteristics, while chi-square tests assessed group differences. Overall survival (OS) was estimated using Kaplan-Meier analysis and compared using log-rank tests. Multivariable Cox proportional hazards models identified independent prognostic factors (p < 0.05 considered significant). Results: A total of 635 patients were identified with ATLL, including 344 (54%) males and 291 (46%) females, with a median age at diagnosis of 59 years (range: 19-90). Most patients came from the Middle Atlantic (NY, NJ, PA) region (33%), followed by the South Atlantic (DC, DE, FL, GA, MD, NC, SC, VA, WV) region (20%) and the East North Central (IL, IN, MI, OH, WI) region (8%). Of the 635 patients, 335 (52%) were Black, 247 (39%) White, and 26 (4%) Asian. Sixty-five (10%) patients were of Hispanic origin. Over half of patients with ATLL (54%) had a median income below $46,000. International Prognostic Index (IPI) score was only available for 16 patients: three (19%) patients were in the high-risk group, 7 (43%) in the high-intermediate group, and 6 (37.5%) in the low-intermediate group. Treatment groups included 357 (56%) patients treated with chemotherapy and 29 (4.5%) who received radiation therapy. Thirty-three (5%) patients underwent hematopoietic stem cell transplant (HSCT), including 27 autologous and 16 allogeneic transplants. The median survival time in the cohort was 9 months (95% CI 7.3-10.7). One-year OS rate in the cohort was 43%, while 2-year and 5-year OS rates were 31% and 23.5%, respectively. Patients over the age of 65 had a significantly shorter median OS than those under 65 (4 vs. 11 months, p=0.001) and were significantly less likely to undergo HSCT (p< 0.001). Black patients had significantly shorter median OS compared to White patients (7.8 months vs 13.3 months, p=0.014), despite similar treatment rates with chemotherapy and HSCT. Median OS appeared to improve over time, from 8 months in patients diagnosed between 2004-2009 to 10 months for those diagnosed between 2016-2020, although this was not statistically significant (p=0.145). Treatment with allogeneic HSCT was associated with significantly prolonged median survival, compared to those who did not receive transplant (50 months vs. 7 months, p<0.05). Additionally, receiving chemotherapy and/or radiation compared to not receiving treatment was also associated with significantly prolonged median survival (p<0.05). Patients treated in the Middle Atlantic region had a median survival of 8.8 months, compared to 23.2 months in the West South Central (AR, LA, OK, TX) region (p< 0.001). Increased education and income levels were not significantly associated with improved survival. There were no significant differences in survival between males and females. Conclusions: We provide contemporary estimates on the epidemiology of ATLL. Factors associated with improved prognosis included undergoing HSCT, radiation, or chemotherapy. We report that increased age and Black race are negative prognostic factors. Regional differences in incidence and survival persist in the US. Our study findings underscore the need for increasing access to treatment, including HSCT for those who are good candidates. Additionally, there remains work to be done to address racial disparities in the care of patients with ATLL.

Background: Splenic marginal zone lymphoma (SMZL) is a rare indolent disease with a median overall survival (OS) of more than 10 years, although a proportion of patients may develop aggressive histology transformation. In a previous report from this large, international dataset, the 10-year cumulative incidence of transformation was 17% (95% 13-21) and in another study of 186 patients, the 10-year cumulative incidence was 14%Click or tap here to enter text.. In this report, we focus on risk factors for transformation as well as clinical characteristics and outcomes of transformed SMZL (tSMZL). Patients and methods: Adults diagnosed with SMZL in 2000-2018 were identified through regional or nationwide population-based registries or from hospital registries. Only patients likely to have SMZL as defined by Matutes et al. were included. Those with discordant lymphoma and/or transformation at diagnosis were excluded. Medical records were reviewed by local clinicians with experience in hematology/oncology, and detailed information on clinical characteristics, treatment lines, and outcomes was collected. Only histologically confirmed high-grade transformations (HT) were included. OS was defined as the time from transformation to death or censoring at last follow-up. Additional analyses stratified by treatment exposure prior to HT and treatment of HT were conducted. Multivariable Cox analyses were performed to determine clinicopathological features associated with transformation and OS. Results: Out of 940 patients with SMZL, 111 developed HT during a median follow-up of 9.1 years. The median time from diagnosis to HT was 3.4 years with an interquartile range of 1.6-7.4 years. Median age at HT was 71 years. Patients with HT shared similar baseline characteristics to those without in terms of age at diagnosis (66.4 vs 67.6), f:m ratio (1.5 vs 1.1) and ECOG ³2 (7.2% vs 7.4%). The 5-yr OS from the time of HT was 42% (CI 95%, 32-54). Of the 111 patients with tSMZL, a complete treatment history from SMZL diagnosis until HT was available for 88 included in the following analyses. By the time of HT, 46 had not received any prior systemic therapy (37 only splenectomy, 9 no therapy), 6 patients had received rituximab alone or combined with splenectomy, and 36 patients had received chemotherapy alone or as part of combined modality treatment. In a uni- and multivariable models for HT, we assessed age, treatment at diagnosis, sex, extra-hilar lymphadenopathy, and extranodal involvement. In both the uni- and multivariable model, age >70 (HR 1.9, 95% CI: 1.1-3.4), immediate treatment including splenectomy (HR 2.0, 95% CI: 1.05-3.6), and extra-hilar lymphadenopathy (HR 1.9, 95% CI: 1.1-3.3) were associated with higher HT hazard, while extranodal involvement (HR 0.23, 95% CI: 0.06-0.84) was associated with a lower HT hazard. At the time of first-line treatment, multivariable analysis revealed similar results and with no association between risk of transformation and treatment strategy (i.e splenectomy alone, rituximab monotherapy or chemotherapy with /without rituximab or splenectomy, and other). At the time of HT, patients who had been previously treated with chemotherapy had an inferior 5-year OS of 24% (95%CI: 13-44%) versus 54% (95%CI: 41-71%) for those who had not received chemotherapy prior to HT. In contrast, there was no difference in the survival of patients that transformed less than or more than 24 months from diagnosis with 5-year OS after HT of 35% (95%CI 20-60%) and 45% (95%CI, 33-61%) respectively. In a multivariable Cox regression analyses of age at time of HT, sex, time since last treatment <24 months, chemo-exposure in previous treatment lines and anthracycline-containing therapy (+/-R) at the time of HT, only prior chemo-exposure was borderline associated with poorer OS (HR 1.8, 95%CI: 0.9-3.5). Conclusion: Patients with SMZL face a notable risk of developing tSMZL over time. Patients in need of immediate treatment at first SMZL diagnosis, age >70 and extrahilar lymphadenopathy had a higher risk of tSMZL and outcomes at the time of HT were poor if patients had been exposed to prior chemotherapy after adjustment for age, sex, and time since last treatment.

Background: Approximately20% of patients with follicular lymphoma (FL) will experience disease progression or death within two years of years (POD24) of immunochemotherapy (IC) (Casulo et al, JCO 2015). A proportion of patients with POD24 have histologic transformation (HT), which heightens the risk of lymphoma-related death (Freeman et al, Blood 2019). To clarify the impact of HT on prognosis in POD24, we analyzed data from the Lymphoma Epidemiology of Outcomes (LEO) Consortium of Real-World Evidence (CReWE) to compare differences in outcomes among patients with POD24 with retained FL histology versus POD24 with HT. Methods: This was a multicenter study among 8 academic cancer centers. Eligible patients hadgrade 1-3a FL at diagnosis between 2003 and 2022, with POD24 following first line IC treatment with BR, R-CHOP, or R-CVP. POD24 was defined as disease recurrence within 24 months of IC. Patients with prior lines of treatment for FL were excluded. Patients with HT at first line IC were excluded. Biopsy at POD24 was obtained at the discretion of the treating physician. Three groups of POD24 were defined: POD24 with biopsy-proven retained FL histology (POD24_FL), POD24 with biopsy-proven HT to aggressive lymphoma (POD24_HT), and POD24 either without a biopsy or indeterminate histology on biopsy (POD24_I). We evaluated second-line treatments at time of POD24. Survival probabilities from second-line treatment initiation were estimated by the Kaplan-Meier method. Results A total of1,122 patients with FL were screened and308 patients with POD24 were identified.Median age at POD24 was 58 years (IQR 50-65).Among available data, race and ethnicity was reported as 76% non-Hispanic White, 3% non-Hispanic Black/African American, 9% Hispanic/Latino (any race), and 1% other minorities. First line therapy was R-CHOP in45% (140/308), BR in 33% (102/308) and R-CVP in 21% (66/308). Most patients (52%) had biopsy-proven retained FL at POD24 (162/308); 30% had no biopsy or indeterminate histology at POD24 (94/308), and 17% had biopsy-proven HT at POD24 (52/308). In the POD24_HT group, 52% received R-CHOP and 21% received intensive salvage chemotherapy as second line therapy. Patients with POD24_FL and POD24_I had similar rates of salvage chemotherapy (21% and 18%), BR (13% and 18%), R-CHOP (19% and 24%), and targeted therapies (8% and 5%), respectively, at second line. Consolidative autologous stem cell transplant was more common in POD24_HT patients at 21% versus 16% in POD24_FL and 6% in POD24_I. Patients with POD24_HT had significantly worse overall survival (OS) compared to POD24_FL (ref), with a hazard ratio of 3.79 (95% confidence interval [CI] 2.46-5.84), even after adjusting for age, FLIPI score, and first-line IC treatment. At 5 years, patients with POD24_HT had OS of 31% compared with an OS of 71% for patients with POD24_FL. Patients with POD24_I had similar outcomes to those with POD24_FL (5-year OS 75% versus 71%, respectively). Event-free survival (EFS) was also significantly lower in POD24_HT compared to POD24_FL: At 2 years, EFS was 27% for POD24_FL (21-35%) and 10% for POD24 _HT (4-23%). At 5 years, lymphoma remained the leading cause of death among patients with POD24, with 20% probability of lymphoma-related death in those with POD24_FL (95% CI 14.2-27.8) compared to 53% probability of lymphoma-related death in patients with POD24_HT (95% CI 40.6-70.7). Conclusions: In our multicenter cohort, we identified remarkable differences between the two biopsy-demonstrated entities of POD24 (i.e., with and without HT). Patients without a biopsy or indeterminate histology had similar outcomes as those with POD24_FL. Patients withearlyrelapse of FL after first-line IC remain a heterogeneous group with poor outcomes and a heightened risk of lymphoma-related mortality particularly compared with nonPOD24 groups. Even with retained FL histology, patients with POD24 had 20% probability of lymphoma-related death within 5 years of second-line treatment initiation. We demonstrate that poor survival is driven in part, but not entirely, by HT. Despite most patients receiving appropriate aggressive treatment, those with POD24_HT represent a distinctly vulnerable population warranting further study in directed prospective studies of both FL biology and clinical trials.

Abstract Progression of disease within 24 months of initial immunochemotherapy (POD24) is a negative prognostic factor for patients with follicular lymphoma (FL). There is no standard treatment after POD24. Assembling an academic-based cohort from the Lymphoma Epidemiology of Outcomes Consortium for Real World Evidence, we evaluated patterns of care and outcomes for 220 patients with FL with POD24 and retained FL histology. Therapy after POD24 was heterogeneous, with no treatment category accounting for >25% of the total. Among patients initially treated with bendamustine-rituximab, rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP) was the predominant second-line choice (48%). Among patients initially treated with R-CHOP, aggressive salvage therapy was the predominant second-line choice (38%). Overall response rate to therapy after POD24 was 64% (95% confidence interval [CI], 56-70); complete response rate was 39% (95% CI, 32-46). The median event-free survival for therapy after POD24 was 9.8 months (95% CI, 7.3-12.1); 5-year overall survival (OS) was 71% (95% CI, 65-78). OS was inferior for patients aged >70 years (hazard ratio [HR], 2.31; 95% CI, 1.27-4.20) and those with high-risk FL International Prognostic Index scores at diagnosis (HR, 2.10; 95% CI, 1.23-3.60). No treatment category stood out with more favorable results. Cause of death was predominantly lymphoma related. Patients with follicular histology at their POD24 event had a low cumulative incidence of transformation (1.1% at 5 years). Our study is among the largest cohorts describing contemporary patterns of care for patients with POD24, providing a focused data set useful for interpreting and designing prospective clinical trials in this population.

Introduction: Splenic marginal zone lymphoma (SMZL) is a rare, indolent disease. There is no universally accepted standard therapy and long-term outcome data are limited. Rituximab monotherapy is increasingly used over splenectomy in the first-line setting despite a paucity of comparative studies. In the absence of randomized trials, large-scale international real-world data studies are critical to evaluate outcomes of different treatment interventions and to understand the natural history of SMZL in the rituximab-era. Methods: Adult patients with SMZL diagnosed between Jan 1 st 2000 and Dec 31 st 2018 were identified using regional/nationwide population-based registries or hospital registries in Europe, the UK, North America, and Australia. Medical records and pathology reports from eligible patients were reviewed locally by clinicians with specialty experience in hemato-oncology. SMZL cases were required to meet the diagnostic criteria by Matutes et al. Detailed data on clinico-pathological features, comorbidities, treatments (including treatment intention), treatment responses and survival outcomes were entered in a central study database. Overall survival (OS) was defined as time from diagnosis until death from any cause or censoring at last follow-up unless stated otherwise. Event-free survival (EFS) was defined as the time from diagnosis until histological transformation, initiation of new chemotherapy or death from any cause. Survival probabilities were estimated using the Kaplan-Meier estimator. Cumulative risk of transformation was estimated with death as a competing risk. Primary endpoints were 10-year OS and 5-year EFS respectivly. Results: A total of 934 patients from 25 sites were included. Median age at diagnosis was 68 years (IQR 60-76) and 54% were female. Bone marrow involvement was present in 96% (564/590) of those assessed, anemia (Hb <12g/dL for women or <13g/dL for men) in 58%, LDH >UNL in 46%, lymphocytosis (>5 x10 9/L) in 34%, and B-symptoms in 34%. Treatment data were available for 97% of patients. Median follow-up was 9.1 years (range 0-23). Watch and wait was the initial strategy in 28% and 88% of patients received at least one line of treatment during follow-up with the most common being splenectomy (45%), immuno-chemotherapy (19%) or rituximab monotherapy (8%). Fifteen percent received “other” treatments (i.e., combinations of listed therapies and/or radiation). The overall response rate to first-line treatment was 88% (95%CI: 85-90%) with 61% (95%CI: 57-64%) achieving CR. Second line (2L) therapy was needed in 34% during follow-up, 3L in 20% and 4L+ in 9%. The 5-year EFS and OS for all patients were 61% (95%CI: 57-65%) and 77% (95%CI: 74-80%) respectively. The 10-year OS and lymphoma-specific mortality (with non-SMZL deaths as competing risk) estimates were 60% (95%CI: 57-64%) and 11% (95%CI: 9-14%) respectively. The 5-year OS after 2L and 3L were 61% (95%CI: 55-68%) and 51% (95%CI: 42-61%) respectively (figure 1). The 10-year cumulative risk of histological transformation was 17% (95%CI: 13-21%), with 5-year post-transformation OS of 42% (32-54%). At the time of transformation, 60% were chemo-naive and 52% had never been treated for SMZL. The 5-year OS for chemo-naive patients with transformation was 54% (95%CI: 41-71%) versus 24% (95% CI: 13-44%) for transformations after (immuno)chemotherapy (p = 0.01). When comparing patients intended for treatment in first line with splenectomy (n=312) versus rituximab (n=70), patients treated with splenectomy more frequently presented with extra-hilar lymphadenopathy (35% vs 18%), splenomegaly (92% vs 87%) and anemia (64% vs 48%). OS was similar for the two groups (Figure 2, p = 0.53). The 5-year EFS were 63% (95%CI: 57-68%) and 64% (95%CI: 54-77%), respectively (p = 0.31). Conclusions: To date, this is the largest real-world study of SMZL with detailed treatment and outcome data. The study shows that histological transformation was not uncommon with 10-year risk of 17%. However, outcomes for the entire cohort were excellent irrespective of initial treatment and both OS and EFS were similar after first line rituximab versus splenectomy. Long-term survival remained relatively high even following multiple lines of therapy.

Background: We previously reported thatearly events in follicular lymphoma (FL), defined as progression of disease within 24 months (POD24) or early transformation to a more aggressive histology, are significantly associated with increased risk of lymphoma related death. To refine clinical management, the FLIPI24 prognostic model was developed to predict the risk of early events after starting immunochemotherapy (IC) (Maurer et al, 2022). The FLIPI24 model was found to be significantly superior to standard clinical models for prediction of both event-free survival at 24 months (EFS24) and overall survival (OS) in internal and external validation sets of patients receiving IC. We sought to evaluate the prognostic ability of the FLIPI24 model in patients with FL not receiving IC. Methods: The cohort consists of prospectively enrolled patients in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) and the multicenter Lymphoma Epidemiology of Outcomes (LEO) Cohorts. Data were collected from medical records by standard protocol with all events verified by medical record review. Eligible patients were those diagnosed with grades 1-3A FL and initiated observation, rituximab monotherapy, radiation, or other non-IC therapy. The FLIPI24 model utilizes 5 continuous variables: age (linear 60-90 years with inflection at age 75), HGB (linear 8-17 g/dL), WBC (linear 4-11x10 9/L), LDH/ULN (linear 0.5-5), and B2M (linear 1-10 mg/L). FLIPI24 risk is grouped as follows: low risk (≤10%], low-average risk (10-15%], average risk (15-20%], high risk (20-40%], very high risk (>40%) for an early event. EFS was defined as time from diagnosis to progression, relapse, (re)treatment, histologic transformation, or death due to any cause. OS was defined as the time from diagnosis until death from any cause. Cox models and Kaplan Meier curves were used to evaluate association between FLIPI24 and EFS or OS. Results: 1542 patients initiating non-IC management approaches at diagnosis from 2002-2020 were identified. 51% were >60 years (IQR 52-70), and 49% were male. Most patients (86%) had FL grade 1-2. 61% of patients met any criteria for high tumor burden per GELF, BLNI, or GITMO based on available variables. Treatment approaches were 833 observation (54%), 315 rituximab monotherapy (20%), 186 radiation (12%), and 208 other non-IC approaches (14%). At median follow-up of 58 months, EFS24 was 73.8% (95% CI: 71.6%, 76.1%), 5-year OS was 90.9% (95% CI: 89.3%, 92.5%) and 253 (16%) patients died. The FLIPI24 score identified poor outcomes among patients with high/very high-risk score (FLIPI24 >20%), with median EFS of 1.8 years (95% CI, 1.3, 3.28) and 5 year OS of 65.1% (95% CI: 55.9-75.8) (Figure 1). When evaluating patient subsets, for patients with high tumor burden (defined based on available variables) and high/very high-risk score, median EFS was 1.6 years and 5 year OS was 64.6% (95% CI: 54.9%-76.1%). Among patients with low tumor burden FL and high/very high-risk score, median EFS was 2.0 years (95% CI: 0.84-NA) and 5 year OS was 66.2% (95% CI: 42.4%-100%). Patients undergoing observation with high/very high-risk score similarly had shortened median EFS of 1.53 years (95% CI: 1.25-NA) and 5 year OS of 68.9% (95% CI: 56.4%-84.1%). The FLIPI24 had superior concordance for OS (c=0.726) compared to the FLIPI (c=0.646) when evaluated in patients not treated with IC. Results were comparable in the subsets of patients observed (c=0.706 vs 0.596) and receiving rituximab monotherapy (c=0.764 vs 0.721). Conclusion: The FLIPI24 model has been previously validated to provide an individual risk score at diagnosis for the likelihood of experiencing an event within 24 months from starting IC. Here we demonstrate that a high FLIPI24 score predicts for poorer outcomes following non-IC strategies including observation, treatment with radiation, and rituximab monotherapy. The FLIPI24 has better prognostic performance for OS than FLIPI in this non-IC population. High FLIPI24 in patients not treated with IC identifies a patient population who should be considered for IC and/or novel frontline therapies when feasible.

Introduction: Histologic transformation (HT) from follicular lymphoma (FL) to an aggressive lymphoma is infrequent but has unfavorable outcomes. Sarkozy et al. (J Clin Oncol, 2019) reported that approximately half of FL-related deaths within the first decade of diagnosis occurred following HT. Our recent analysis showed heterogeneous outcomes with median overall survival (OS) of 61 months (Day et al., ASH, 2022). Prognostic tools post HT would be clinically useful but development has been limited by small cohort sizes. Factors previously associated with outcomes following HT have included age, time to progression, prior therapy, anthracycline exposure, and early HT. Utilizing the Lymphoma Epidemiology of Outcomes (LEO) Consortium of Real World Evidence (CReWE), we describe patterns of care and evaluate other prognostic factors following HT. Methods: This multicenter observational cohort consists of prospectively enrolled patients in the LEO Cohort, and patients with HT retrospectively identified at LEO centers. Patients diagnosed with biopsy proven grade 1-3A FL at diagnosis, and a subsequent biopsy showing HT to an aggressive lymphoma (FL grade 3B, diffuse large B cell lymphoma [DLBCL], or high-grade B cell lymphoma [HGBCL]) between 2002-2022, were eligible for the study. Patients with a component of FL grade 3B, DLBCL, or HGBCL at diagnosis were excluded. HGBCL was defined as double or triple hit or another aggressive subtype. OS was defined as the time from HT until death from any cause and calculated via Kaplan-Meier. Associations between clinical factors at time of HT and/or diagnosis and OS were evaluated using Cox models. Cause of death was evaluated using a competing risk approach. Results: Overall, 328 patients were confirmed with HT during the study period, 41% were female, and the median age at HT was 63 years (interquartile range [IQR] 56-70). The median time from diagnosis to transformation (TDT) was 35 months (IQR 12-66). At HT, 88% had advanced stage disease (III-IV) and LDH was elevated in 49%, while few patients exhibited B symptoms (5%) and ECOG performance status was >2 in 9%. 23% did not receive systemic therapy prior to HT. For those with prior therapy, the median time from prior therapy to HT was 15 months (IQR 7-39). The most frequent treatment regimens following HT were CD20-CHOP (42%), followed by platinum-based salvage therapy (20%), R-EPOCH (10%), CD20-Benda (8%), R-Mono (4%), and R-Gem-Ox (3%). 50 (15%) patients underwent consolidation with autologous stem cell transplant, 3 underwent allogeneic transplant (30 platinum-based, 15 CD20-CHOP, 5 R-EPOCH, 3 Other), and 2 received CAR T-cell therapy (Figure 1). After median follow-up of 85 months from HT, 170 patients had died; 5-year OS was 52% and median OS was 65 months (95% CI: 55-107). Among 160 patient deaths, cause was most often lymphoma-related (progression, n=107 [63%]; therapy-related, n=14 [7%]) compared to non-lymphoma (n=20, 13%) or missing/unknown causes (n=29, 17%). Clinical factors at the time of HT that were associated with worse OS include: ECOG PS >2, age ≥70, IPI 3-5, and shorter TDT (<24 months), hemoglobin <10 g/dl and elevated LDH. A transformation to HGBCL was also associated with inferior OS (Table 1). OS did not significantly differ by gender, BMI, stage, presence of B-symptoms, absolute lymphocyte count, number of extranodal groups, presence of bulky disease at HT, or response to prior FL treatment. Factors at the time of FL diagnosis that were associated with decreased OS after HT included FLIPI score 3-5 (high risk), FLIPI 2 (moderate risk), and FL grade 3A at diagnosis. Exposure to any systemic therapy for FL prior to HT was associated with shorter OS, with the worst outcomes in patients receiving an anthracycline prior to HT. POD24 to frontline immunochemotherapy was associated with inferior OS after HT (Table 1). Conclusions: Patterns of care in Transformed FL are heterogeneous and vary greatly in intensity. These data confirm previous reports that age, early HT, and any systemic therapies prior to HT are negative prognostic indicators for OS. At HT elevated LDH, low hemoglobin, POD24 status, poor performance status, and HT to HGBCL were associated with poor outcomes following HT. These data provide a basis for future prognostic indices to identify patients with highest risk of lymphoma related mortality for whom study of novel treatments is greatly needed.

7573 Background: While most patients (pts) with follicular lymphoma (FL) usually have favorable outcomes, those with refractory disease after first-line anti-CD20 based immunochemotherapy (IC), or progression within 24 months of diagnosis (POD24) have higher risk of premature death. There are no standard approaches for treating this vulnerable group and studies testing novel agents are ongoing in this setting. We sought to investigate clinical practice treatment choices and efficacy for pts with POD24 that align with eligibility criteria for the randomized SWOG1608 which compares IC with novel agents in this population. Methods: This was a multicenter observational cohort study from the LEO Consortium. Eligible pts had grade 1-3a FL diagnosed between 1/1/2002 and 2/1/2019, and initiated therapy after POD24 to first-line bendamustine or CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) based IC. Observation, radiotherapy, or rituximab monotherapy were permitted prior to IC and pts with transformation prior to the subsequent therapy after IC were excluded as per S1608. Outcomes of interest were overall and complete response rate (ORR/CR), progression-free survival (PFS), and overall survival (OS). Results: We identified 196 eligible pts with early progression to IC (39% antiCD20 Benda; 61% antiCD20 CHOP) who received subsequent therapy. Median age at post IC treatment was 57 years, 78% grade 1-2 FL. Treatments for pts with POD24 included CHOP- or Benda-based in 31%, salvage/hematopoietic stem cell transplant (HSCT) in 27%, novel therapies in 10% (including phosphatidylinositol 3-kinase inhibitors), antiCD20 monotherapy in 9%, and lenalidomide-based treatment in 8% (table); 21% of pts were treated on clinical trials. Across all treatments, ORR (CR) was 63% (37%) (95% CI: 55-70). At a median follow up of 6.2 years, 2 year PFS was 22% (95% CI: 17%-29%) and 5 year OS was 71% (95% CI: 65-79). Outcomes by regimen are shown in the table. Conclusions: Pts with FL experiencing POD24 following first-line IC are treated heterogeneously, with many pts still receiving IC as subsequent therapy. Despite modest CR rates and low 2-year PFS, 5-year OS appear to be improving compared to historical outcomes. This supports the ongoing need to investigate novel treatments in this population. [Table: see text]