Myeloid sarcoma (MS) is a rare extramedullary manifestation of acute myelogenous leukemia (AML). The mass is composed of primitive myeloid cells that can occur in a variety of organs, most commonly the skin, lymph nodes, GI tract, bone, breast, and CNS. Involvement of the genitourinary tract is rare. Consensus on treatment of MS has not been established, but management typically involves systemic therapy, such as chemotherapy or allogeneic hematopoietic stem cell transplant as well as palliative local therapies such as radiation or surgery. Outcomes of MS using novel AML therapies, such as BCL-2 inhibitors or IDH inhibitors, remain undescribed. We describe a rare case of a 70-year-old man presenting with MS of the urinary bladder complicating known secondary AML (RUNX1 and IDH2 mutated). Prior to development of bladder MS, the patient had received decitabine, enasidenib, and venetoclax. Following diagnosis, he was treated with cytarabine and venetoclax. To our knowledge, this is the first case of bladder MS treated with a BCL-2 inhibitor.

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e15615 Background: Gallbladder cancer (GBC) is a rare cancer; the minority of patients have resectable tumor at diagnosis. Based on retrospective, single-institution data, extended cholecystectomy (EXT) has been recommended over simple cholecystectomy (CHOL) in >T1 tumors; however, effect of EXT on survival is unclear. Thus, we evaluated the survival of patients with resectable GBC at our institution. Methods: Retrospective analysis from 1/1/2005 to 1/1/2016 for patients with GBC. Patients with advanced or metastatic disease were excluded. The Recurrence-free survival (RFS) and overall survival (OS) were calculated using the Kaplan-Meier method. Results: 68 patients with GBC; 26 (38%) with early disease. Twelve patients had EXT. Patient/tumor characteristics are shown in Table. Median RFS was 22 months (95% CI: 9-not reached) and OS was 25 months (95% CI: 15-not reached) for the entire cohort. Median RFS was increased in CHOL (30 months) relative to EXT (9 months); p=0.73. OS appeared similar between the two groups (25 vs. 23 months for CHOL and EXT group, respectively). Conclusions: EXT appears to improve RFS with no effect on OS in patients with early GBC. Due to the limitations of small sample size and retrospective analysis, multi-institutional collaborations are necessary to better identify optimal management. [Table: see text]

605 Background: 5-FU and mitomycin-C (MMC) with radiotherapy (RT) remain an established treatment for pts with LA (T2-4, N0-1, M0 or T1-4, N2-3, M0) AC. Genetic mutations in 2 major metabolizing enzymes for 5-FU; DPYD and TYMS have been associated with clinical response and toxicity. However their place in treatment of AC remains undetermined. Methods: We retrospectively reviewed 21 pts with LA AC treated between 2012 - 2018. All pts were treated with 5-FU 1,000mg/m2/day continuous IV infusion 1–4 and 29–32, MMC 10mg/m2 IV bolus Days 1 and 29 plus RT. Acute toxicity was recorded and discussed during weekly multidisciplinary meetings. The worst grade was scored from start of treatment until 30 days after the last fraction of radiotherapy according to the NCI-CTCAE, v4.03. Tumor response was evaluated by DRE and palpation of inguinal nodes during treatment, at the end of treatment, and radiological imaging 4–6 weeks after completion of treatment. Pts who developed ≥3 toxicities were tested for DPYD and TYMS genes (2 major polymorphisms has been associated with altered TYMS: polymorphic 28bp tandem repeat polymorphism in 5’-untranslated region (5’UTR) into TYMS sequence enhancer region (TSER) and TYMS 1494del, is a 6-base pair (bp) deletion polymorphism in 3’-UTR. Results: 6/21 ptsdeveloped severe toxicities (Caucasians; 5 females, 1 male; age range: 42 -68 yrs) consisting of grade ≥3 pancytopenia, neutropenia, thrombocytopenia, mucositis, nausea, rash and nephritis. The most common genetic mutations found in these pts included TYMS 2RG/3RC (2), 3RG/3RC (1), 2R/2R (2), TYMS 3 ' UTR del/Ins (2) and DPYD c.2864A>T heterozygous (1). Treatment was changed in 2 pts to MMC 10 mg/m2 Day 1 and 29 with cisplatin 25 mg/m2/week plus RT. These 2 pts reached pCR at 70 days and other 4 pts at 140 days. Conclusions: Molecular testing for DPYD and TYMS genes can allow us to identify pts who are most likely to respond or face severe toxicity to 5-FU. Combining radiation with MMC and cisplatin in pts with LA AC is feasible and EORTC is currently comparing this combination with MMC/5-FU in a large phase III trial.