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AbstractBackgroundAcute promyelocytic leukemia (APL) is a unique leukemia subtype requiring specialized treatment including all‐trans retinoic acid (ATRA). A prior report demonstrated worse outcome among young children <5 years old compared with older children.MethodsWe evaluated outcomes for pediatric patients (<18 years old; N = 83) with APL treated on North American intergroup study CALGB 9710 at Children's Oncology Group sites. Induction and consolidation included ATRA, cytarabine, and anthracyclines. Patients ≥15 years old were randomized to addition of arsenic trioxide (ATO) consolidation. All patients were randomized to ATRA maintenance with versus without oral chemotherapy.ResultsThe estimated 5‐year overall survival (OS) rate was 82%, and the event‐free survival (EFS) rate was 54%. Seven patients (8.4%) died during induction due to coagulopathy. Maintenance randomization demonstrated that addition of oral chemotherapy to ATRA significantly reduced relapse rate, but difference in EFS did not reach statistical significance (P = 0.12; 5‐year rates [95% CI]: 41% [17%–64%] ATRA only vs 72% [56%–88%] ATRA plus chemotherapy). There was no difference (P = 0.93) in EFS for age <5 years versus 5–12.99 years versus 13–17.99 years (5‐year rates: 56%, 47%, and 45%, respectively). Among adolescents 15–17.99 years old in the ATO randomization, there was a significantly lower relapse risk at 5 years for those receiving ATO (0% ATO vs 44% no ATO; P = 0.02).ConclusionOur data demonstrate that intensified ATRA, cytarabine, and anthracycline chemotherapy is effective for pediatric APL including very young patients, but early deaths and relapses remain barriers to cure. Further improvements are likely with incorporation of ATO into pediatric APL regimens.

Heřmanský–Pudlák syndrome (HPS), a rare autosomal recessive disorder, manifests with oculocutaneous albinism and a bleeding diathesis. However, severity of disease can be variable and is typically related to the genetic subtype of HPS; HPS type 6 (HPS‐6) is an uncommon subtype generally associated with mild disease. A Caucasian adult female presented with a history of severe bleeding; ophthalmologic examination indicated occult oculocutaneous albinism. The patient was diagnosed with a platelet storage pool disorder, and platelet whole mount electron microscopy demonstrated absent delta granules. Genome‐wide SNP analysis showed regions of homozygosity that included the HPS1 and HPS6 genes. Full length HPS1 transcript was amplified by PCR of genomic DNA. Targeted next‐generation sequencing identified a novel homozygous missense variant in HPS6 (c.383 T > C; p.V128A); this was associated with significantly reduced HPS6 mRNA and protein expression in the patient's fibroblasts compared to control cells. These findings highlight the variable severity of disease manifestations in patients with HPS, and illustrate that HPS can be diagnosed in patients with excessive bleeding and occult oculocutaneous albinism. Genetic analysis and platelet electron microscopy are useful diagnostic tests in evaluating patients with suspected HPS.Clinical Trial registration:Registrar: ClinicalTrials.govWebsite: www.clinicaltrials.govRegistration Numbers: NCT00001456 and NCT00084305.

11534 Background: To date, there are no validated blood-based biomarkers of predicting response to PD-1 blockade. We previously reported that Bim is a downstream signaling molecule of the PD-1 pathway, and that measurement of Bim levels in circulating T-cells may predict and monitor responses to anti–PD-1 therapy in melanoma. We have identified the existence of sPD-L1 in cancer patients and showed that the sPD-L1 is biologically active and capable of triggering apoptosis in activated T-cells. Here we evaluated T cell Bim and sPD-L1 in the peripheral blood (PB) as biomarkers of response in a cohort of patients with metastatic melanoma and lung cancer undergoing anti-PD1 therapy. Methods: 60 pts treated with anti-PD-1 had PB collected at baseline and at radiographic tumor evaluation. Frequencies of Bim+ T cells and Bim median fluorescence intensity (MFI) were measured by flow cytometry in gated tumor-reactive CD11ahighPD1+ CD8+ T cells. We also measured levels of sPD-L1 at baseline and serially during treatment with sPD-L1 ELISA. Baseline Bim and sPD-L1 levels and percent change in Bim levels in patients (pts) who had a radiographic response (CR/PR) were compared to those who had progressive disease (PD) at 12 wks. Results: Similarly to previously reported preliminary data, pts with objective response (CR/PR, 15/60) after 4 cycles of anti-PD1 therapy had higher frequency of Bim T cells at baseline compared to pts with PD (16/60) (mean 43% vs. 30%, P = 0.0484). The frequencies of Bim+ T cells decreased significantly after the first 3 months of treatment in responders compared with progressors (mean -16% vs. + 40% P = 0.0111). High baseline sPD-L1 were associated with progression on anti-PD1 therapy (mean 2.8 ng/mL vs. 0.7 ng/mL, p = 0.07, n = 13) and the levels increased by the first tumor assessment in patients resistant to anti-PD-1. Conclusions: Measurements of Bim and sPD-L1 levels may help to select patients who are likely to benefit from anti-PD1 monotherapy versus combinatorial strategies, and provide a new non-invasive way to monitor response to anti-PD-1 blockade. A larger validation study is underway.

e21054 Background: Up to 50% of patients undergoing resection for advanced melanoma experience recurrence. Identification of preoperative prognostic biomarkers is needed to ascertain risk of relapse and guide postoperative management. Lactate dehydrogenase (LDH) represents a strong prognostic factor in unresectable metastatic (stage IV) melanoma, but its relevance in patients with resected stage III or IV disease remains unknown. Methods: We retrospectively analyzed data from patients with stage III and IV melanoma who had undergone complete resection of disease and received follow-up treatment at Mayo Clinic, Rochester between January 1, 2000 and January 31, 2012. Clinical data were collected from electronic records. Survival data were estimated using the Kaplan-Meier method. Associations of preoperative LDH with time to relapse and death were evaluated using Cox proportional hazards regression models and summarized with hazard ratios and 95% confidence intervals. Results: A total of 154 subjects with resectable stage III or IV melanoma were included in the study. Median age at the time of resection was 58; 54 (35.1%) were female. One-hundred sixteen (75.3%) patients were classified as stage III and 38 (24.7%) stage IV. Adjuvant systemic treatment was administered in 75 (48.7%) patients and adjuvant radiation in 32 (20.7%). Median duration of follow-up was 4.0 years. Sixteen (10.3%) patients had preoperative LDH above the upper limit of normal. Each 50-unit increase in LDH was associated with a 15% increased risk of relapse (HR 1.15; p = 0.040) and 23% increased risk of death (HR 1.23; p = 0.001). After adjusting for age, gender, stage, number of sites, adjuvant systemic treatment, and adjuvant radiation, preoperative LDH remained associated with time to death (HR 1.25; p = 0.002). Preoperative LDH greater than the upper limit of normal was associated with increased hazard of death, both with univariate (HR 2.44; p = 0.005) and multivariate (HR 2.17; p = 0.017) analyses. Conclusions: This study supports the role of elevated preoperative LDH as a predictor of inferior outcomes in patients with advanced melanoma. Further study to correlate LDH to outcomes in the era of adjuvant immunotherapy is required.

e18096 Background: Newly approved and emerging agents with novel mechanisms of action present unique challenges to treating patients with relapsed/refractory multiple myeloma (RRMM), including keeping abreast of rapid and ever-aggregating data on their safety, tolerability and efficacy. To address these challenges, an education activity focused on new and emerging therapies for RRMM was developed and learner responses were evaluated to determine the impact of education. Methods: A live-online 1-hour video panel discussion with slides, polling, and live questions was produced in 2016 and made available on-demand at OMedLive.com for 6 months. Survey responses (pre-, post-, 8 weeks post-activity), polling responses, and live questions asked were tracked to measure engagement, lessons learned, and additional education gaps. Results: 51 of 288 learners completed all pre/post/follow-up surveys, 67% of which reported the activity positively impacted patient experience or outcome and 61% reported it positively impacted their clinical practice. These learners reported improvements in their ability to: assess the relative safety and efficacy of emerging agents (50%), differentiate available agents and their relative efficacy (50% with proteasome inhibitors, 39% with monoclonal antibodies), see the potential benefit of HDAC inhibitors (35%), use combination regimens (29%), and adjust treatments for patients who’ve experienced disease progression (29%). As the result of education, 95 of 288 learners reported commitments to change in regards to: medical/practice knowledge (95%), care attitudes (89%), practice behavior (76%), and patient clinical outcomes (81%). Learners also demonstrated improved competence via a case scenario which required identifying the optimal next step for a patient with biochemical progression, and improved knowledge on the characteristics of daratumumab, elotuzumab, and selinexor. Conclusions: New and emerging therapies promise to improve the lives of patients with RRMM, but complicates the already difficult task of managing the disease. Ongoing education on RRMM is recommended and can yield immediate and sustained gains in knowledge, competence, and performance.

e15168 Background: 2-8% of all colorectal cancer (CRC) cases are in younger adults (YAs), patients (pts) less than age 50. However, current understanding of CRC in YAs is inadequate, especially that of sporadic onset. We conducted a study to describe the landscape of genomic alterations in YA CRC pts presenting to a large academic practice. Methods: Adult pts with CRC presenting to The Ohio State University Comprehensive Cancer Center oncology clinics were offered next generation sequencing (NGS) through a customized 22-gene Ion AmpliSeq Mutation Panel as part of clinical care. Commonly mutated areas of select genes (including AKT1, ALK, BRAF, EGFR, ERBB2/4, FBXW7, FGFR1/2/3, KRAS/NRAS, MET, NOTCH1, PIK3CA, PTEN, TP53) were sequenced from tumor sections. Institutional review board approval was obtained to retrospectively analyze this NGS testing between 1/2013-3/2016. Results: 258 CRC pts underwent genomic profiling. 57 pts (22.1%) were YAs at diagnosis (range 22-49 years); 20 pts (7.8%) were 40 years old or younger. 31 YA pts (54.4%) had metastatic disease. Of the YAs with CRC, 18 pts (31.6%) were diagnosed with R-sided colon, 16 pts (28.1%) with L-sided colon, and 22 pts (38.6%) with rectal cancer. 110 genomic alterations were found in YA pts, with a mean of 1.9 mutations per tumor (range 0-6); 35 (31.8%) of these in 32 (56.1%) YA pts were actionable. Of these 110 alterations, 41.8% were in TP53, 28.2% in KRAS/NRAS, 10.0% in PIK3CA, 3.6% in BRAF, 3.6% in FBXW7, and 2.73% in PTEN. 6 YA pts (10.5%) had microsatellite instability (MSI-H). Only 1 pt had concomitant MSI-H and a BRAF mutation; 4 pts with BRAF mutations were microsatellite stable. Comparing our YA pts to a separate cohort of pts age > 50 who had testing done, no significant difference was seen in mutation incidence in KRAS/NRAS (p = 1.0), TP53 (p = 0.3), PIK3CA (p = 0.128), or BRAF (p = 1.0). Conclusions: Genomic profiling through a targeted NGS panel is feasible as part of routine clinical practice. There is disagreement in the literature on genetic mutations in YA compared to older age CRC pts. Knowledge of the genomic landscape in YAs with CRC will lead to improved understanding of the underlying biology of CRC in YAs as it differs from CRC in older pts, and could impact future care of this cohort.