JRB provided and cared for patients. Collection and assembly of data was conducted by MSD, HTK, SV, JB, and AS, while the data analysis and interpretation was performed by MSD, HTK, SV, and JRB. MSD wrote the first draft of the manuscript and all authors participated in its writing and gave approval for publication.

Introduction FCR remains the only therapy other than allo transplant proven to provide a significant chance of functional cure with very long term follow-up for young, fit patients with mutated IGHV CLL. Given the excellent efficacy and tolerability of ibrutinib in a broad population of young, fit CLL patients, we designed the frontline iFCR study to investigate whether time-limited novel agent plus chemoimmunotherapy could provide durable remission for CLL patients irrespective of IGHV status. We previously reported that with a median follow-up of 16.5 months, the rate of CR with bone marrow undetectable minimal residual disease (BM-uMRD) 2 months post-FCR (primary endpoint) was 33%, and that 84% of patients achieved BM-uMRD as best response (Davids et al., Lancet Haem, 2019). Here, we report updated data with longer follow-up, with all patients having had the opportunity to complete 2 years of ibrutinib maintenance following iFCR. Methods This is a multicenter, single arm, phase 2 investigator sponsored trial (NCT02251548) which enrolled CLL patients age ≤65 years without restriction by IGHV mutation status, all of whom met iwCLL treatment criteria. Ibrutinib 420 mg daily was given for 7 days, then combination ibrutinib with FCR for up to 6 cycles. Responders continued on ibrutinib maintenance, and patients with BM-uMRD after 2 years of maintenance discontinued therapy. Response was assessed by 2008 iwCLL criteria, and toxicity by CTCAE v4.03 and iwCLL criteria. The primary objective was to determine the rate of CR/CRi with BM-uMRD 2 months after iFCR combination. Secondary objectives were to assess response rates, PFS/OS, rates of BM-uMRD after 2 years of ibrutinib maintenance, and safety/tolerability. Results Between October, 2014, and April, 2018, 85 patients were enrolled at 9 US sites.As previously reported, the median age was 55 years (range 38-65). IGHV was unmutated in 46/79 patients (58.2%). Deletion of 17p and TP53 mutation were present in 4/83 (4.8%) and 3/81 (3.7%) patients, respectively; 2 of these patients had both. The median number of FCR cycles completed was 6 (range 1-6). Median follow-up is now 40.3 months (range 3.1-76). Median number of ibrutinib maintenance cycles is 24 (range 0-81). By ITT analysis, the rate of CR with BM-uMRD at any point on study is now 55% (47/85 patients), and best rate of BM-uMRD remained 84% (71/85). After 2 years of ibrutinib maintenance, the rates of CR/CRi, BM-uMRD, and PB-uMRD in patients with available data were 77% (44/57), 81% (50/62), and 81% (55/68), respectively, with no differences based on IGHV status. At the median follow-up time of 40 months, PFS and OS for all patients were 97% and 99%, respectively (see Figure, below). Thirteen of 61 patients (21.3%) who completed iFCR and started ibrutinib maintenance in a BM-uMRD state have had recurrent BM-MRD, with median time to MRD recurrence not yet reached. Seven patients underwent retreatment with ibrutinib monotherapy (5 due to clinical progression and 2 due to recurrent BM-MRD without clinical progression), and all 7 achieved PR with re-treatment. Median time on re-treatment is 12.8 months (range 4.2-26.2), and none of these 7 patients have progressed on re-treatment. One patient died 17 months into ibrutinib maintenance due to presumed sudden cardiac death. In the updated safety analysis, the most common treatment-emergent Gr 3/4 adverse events were hematologic, including neutropenia 40% (up from 35%), thrombocytopenia 32% (unchanged), and anemia 11% (unchanged). Ten patients (12%, up from 9%) experienced Gr ≥3 febrile neutropenia, and 20 patients (24%, up from 11%) had Gr ≥3 infection. Any Gr atrial fibrillation was observed in 8%, and ventricular arrhythmia in 1 patient. No major bleeding events occurred. Two patients developed MDS, and both are now in CR for CLL and MDS after undergoing allo transplant. No patients developed Richter's syndrome. Conclusions With longer term follow-up (median of 40.3 months), most patients treated with iFCR have continued to maintain deep responses, including patients with unmutated IGHV. The safety profile remains consistent with the individual toxicities of ibrutinib and FCR. Among the few patients with recurrence after this time-limited therapy, all have responded to re-treatment with ibrutinib monotherapy. iFCR is worthy of exploring in comparative studies in younger, fit CLL patients who desire the possibility of functional cure with time-limited therapy. Figure 1 Figure 1. Disclosures Davids: Ascentage Pharma: Consultancy, Research Funding; Celgene: Consultancy; Eli Lilly and Company: Consultancy; Janssen: Consultancy; MEI Pharma: Consultancy; Merck: Consultancy; Research to Practice: Consultancy; Takeda: Consultancy; Novartis: Consultancy, Research Funding; BeiGene: Consultancy; Adaptive Biotechnologies: Consultancy; Astra-Zeneca: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; MEI Pharma: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; Surface Oncology: Research Funding; AbbVie: Consultancy. Brander: NCCN: Other: panel member; Verastem: Consultancy; MEI Pharma: Research Funding; Juno Therapeutics/Celgene/Bristol Myers Squibb: Research Funding; ArQule: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Pfizer: Consultancy, Other: Biosimilars outcomes research panel; DTRM: Research Funding; ArQule/Merck: Consultancy; LOXO: Research Funding; AbbVie: Consultancy, Other: informCLL registry steering committee, Research Funding; TG Therapeutics: Consultancy, Research Funding; AstraZeneca: Research Funding; Novartis: Research Funding; Genentech: Consultancy, Research Funding; Ascentage: Research Funding; BeiGene: Research Funding. Montegaard: AbbVie: Consultancy; AstraZeneca*-: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy. Alencar: Seattle Genetics: Consultancy; Kite Pharma: Consultancy; Karyopharm: Consultancy; Janssen: Consultancy; Incyte: Consultancy; Epizyme: Consultancy; Celgene: Consultancy; BeiGene: Consultancy; Amgen: Consultancy. Jacobson: Humanigen: Consultancy, Honoraria, Other: Travel support; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Celgene: Consultancy, Honoraria, Other: Travel support; AbbVie: Consultancy, Honoraria; Axis: Speakers Bureau; Lonza: Consultancy, Honoraria, Other: Travel support; Clinical Care Options: Speakers Bureau; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Nkarta: Consultancy, Honoraria. Armand: Infinity: Consultancy; Pfizer: Consultancy; Kite: Research Funding; Tensha: Research Funding; IGM: Research Funding; Roche: Research Funding; Genentech: Consultancy, Research Funding; AstraZeneca: Consultancy; Epizyme: Consultancy; Enterome: Consultancy; Regeneron: Consultancy; C4: Consultancy; GenMab: Consultancy; Tessa Therapeutics: Consultancy; Miltenyi: Consultancy; Morphosys: Consultancy; Daiichi Sankyo: Consultancy; Otsuka: Research Funding; Sigma Tau: Research Funding; Celgene: Consultancy; ADC Therapeutics: Consultancy; Adaptive: Consultancy, Research Funding; Affimed: Consultancy, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding. Crombie: Roche: Research Funding; Merck: Research Funding; Abbvie: Research Funding; Bayer: Research Funding; Karyopharm: Consultancy; Incyte: Consultancy. LaCasce: Bristol-Myers Squibb Company.: Other: Data Safetly and Monitoring. Arnason: Juno/BMS: Honoraria. Hochberg: Trapelo Health: Consultancy; Leuko: Consultancy. Abramson: Bristol-Myers Squibb Company: Consultancy, Research Funding; Kite Pharma: Consultancy; Novartis: Consultancy; Morphosys: Consultancy; C4 Therapeutics: Consultancy; EMD Serono: Consultancy; Genmab: Consultancy; Bluebird Bio: Consultancy; Kymera: Consultancy; BeiGene: Consultancy; Incyte Corporation: Consultancy; Astra-Zeneca: Consultancy; Allogene Therapeutics: Consultancy; Seagen Inc.: Research Funding; AbbVie: Consultancy; Karyopharm: Consultancy; Genentech: Consultancy. Brown: Gilead, Loxo/Lilly, SecuraBio, Sun, TG Therapeutics: Research Funding; Invectys: Other: Data Safety Monitoring Committee Service; Abbvie, Acerta/Astra-Zeneca, Beigene, Bristol-Myers Squibb/Juno/Celgene, Catapult, Eli Lilly, Genentech/Roche, Janssen, MEI Pharma, Morphosys AG, Nextcea, Novartis, Pfizer, Rigel: Consultancy. OffLabel Disclosure: Ibrutinib being used to enhance the efficacy of FCR

e13114 Background: GATA3 encodes a transcription factor, which is involved in activation and suppression of genes involved in cell maturation. GATA3 is necessary in the adult mammary gland to maintain the integrity and function of the luminal epithelium. Methods: METABRIC project funded by cancer research UK, the British Columbia cancer foundation and the Canadian breast cancer foundation mapped 173 gene mutations and amplifications in 2,433 primary breast tumors. Retrospective analysis was done for patients with invasive ductal carcinoma of the breast in the age group 30-60; to study the effect of GATA3 mutation on survival. Median survival was obtained from Kaplan-Meier plot, and mortality between groups was compared by Odds ratio (OR). Results: A total of 1500 patients across all age groups had invasive ductal carcinoma. 650 were within the age group 30-60; of which 234 died due to the disease, 360 were alive and 55 died due to other causes. 398 patients (61.2%) tested positive for estrogen receptor (ER) and 521 patients (80.2%) were negative for HER2 (human epidermal growth factor receptor 2). TP53 (50%) and PIK3CA (36%) mutations were more prevalent. GATA3 mutation was found in 79 patients (12.34%); among which, all 79 patients tested positive for ER (100%) and 74 patients (94.9%) negative for HER2. 10 patients (12.7%) died due to the disease, 62 patients (78.5%) were alive and 7 patients (8.9%) died due to other causes. Hence, patients with GATA3 mutations were more likely to survive (OR 4.66; CI 2.33-9.29 p < 0.0001) than patients without the mutation. The median survival for patients with GATA3 mutation (300 months) was also greater than patients without the mutation (219 months). In addition, patients with GATA3 mutation were more likely to be ER positive and HER2 negative. Conclusions: In the mammary gland, GATA3 is required for luminal epithelial cell differentiation. Loss of GATA3 results in de-differentiation to stem cell phenotype. It is found that GATA3 mutation correlates with a better prognosis compared to more common TP53 and PIK3CA gene mutations.

34 Background: Observational studies have raised the possibility that use of statins may reduce the incidence and overall risk of cancer. In contrast, some randomized trials have consistently shown no effect of statins at cancer incidence or mortality. However, data about the potential effect of statins on overall survival of breast cancer are limited. We intend to examine the role of statins at overall survival of women diagnosed with breast cancer. Methods: A retrospective observational study was conducted from 1993 to 2007, using data from McLaren Regional Medical Center in Flint, Michigan on women diagnosed with breast cancer. Patient's characteristics including age at diagnosis, race, stage and use of statin with dosage were recorded. Patients with coronary artery disease were excluded to eliminate the confounding effect. The three-year overall survival was considered the primary outcome. Results:s A total of 392 women diagnosed with breast cancer were identified. 146 patients were on statins therapy prior to diagnosis (group 1), and 246 patients were not on statins (group 2). African American percentage was 7%. Mean age at diagnosis was 65 for both groups. Atorvastatin was the most used treatment with a dose of 20 mg daily. Patients were classified according to the TNM staging system of breast cancer as stage I, II, III, IV (58%, 31%, 8%, 3%) for group 1, and (62%, 32%, 4%, 2%) for group 2 respectively. The 3-year stage-specific survivals were calculated and compared between the two groups using Fisher's exact test (Table). Overall survival was not statistically significant between the two groups. Conclusions: Our study did show that statins do not affect the three-year overall survival of breast cancer at early stages, but it may improve the outcome at advanced stages. A larger national data review is warranted. [Table: see text]

189 Background: Despite the major advances in early detection and treatment of breast cancer (BC), African American women, continued to have a higher mortality rates than Caucasians. Many studies have failed to identify a key factor to explain racial disparities in breast cancer outcome. These disparities persist even after controlling for insurance and socioeconomic settings. Data about delays in treatment initiation are limited and inconclusive. We intend to compare the time from diagnosis to the initiation of treatment between African American and Caucasian women diagnosed with BC in a single community-based cancer registry. Methods: Women aged 18 to 64 years with breast cancer were identified, between 1993 and 2009, using data from the Tumor Registry at Hurley Medical Center in Flint, Michigan. Patient’s characteristics obtained include age at diagnosis, race, stage, date of diagnosis, and date of treatment initiation. All patients were previously insured or became insured after diagnosis. Time from diagnosis to the initiation of treatment was calculated in days and compared between African American and Caucasian women using t-test. Results: A total of 1016 patients have been identified with diagnosis of BC. 23 patients were excluded due to missing data. 993 patients were analyzed. African Americans were 355 (36%), Caucasians 617 (62%), and other ethnicities 21 (2%). Mean age at diagnosis was (48.9) for African Americans versus (51.45) for Caucasians (p = 0.005). African American women were more likely to present with advanced stage (III, IV) than Caucasians (18% versus 12%, p = 0.009). African American women had significant delay in the treatment initiation of BC compared to Caucasians (31.11 versus 21.52 days, p < 0.0001). Conclusions: African American women were diagnosed with breast cancer at younger age and more advanced disease than Caucasians. African American women experienced significant delay in the initiation of therapy after diagnosis compared to Caucasians. However, the impact of an average delay of 10 days in treatment on overall survival is unknown. The exact explanation of this disparity is yet to be determined.