Acute suppurative thyroiditis (AST) is an uncommon, potentially life-threatening cause of a rapidly enlarging neck mass. It may present similarly to subacute thyroiditis, a relatively benign and self-limiting condition. We report a case of AST in an adult intravenous (IV) drug user with a preexisting goiter who presented with a left forearm abscess that grew methicillin-sensitive Staphylococcus aureus. In this particular case, clinical suspicion for AST was high. As a result, early IV antibiotic therapy was initiated, and this led to rapid clinical improvement furthermore preventing airway compromise. To our knowledge, this is the first case of AST in the literature resulting from likely hematogenous spread in the setting of IV drug use and a preexisting goiter. Overall, this case highlights the importance of assessing risk factors for AST in patients whose presentations may seem more typical of subacute thyroiditis. Such an approach will lead to timely diagnosis and treatment to avoid potentially devastating consequences.

11555 Background: Leiomyosarcoma (LMS) is a rare group of mesenchymal malignancies found in the uterus, retroperitoneum, skin, or other soft-tissue sites. Treatment for LMS is extrapolated from trials including both uterine (uLMS) and non-uLMS subtypes, although whether they respond similarly and have similar outcomes from treatment is not clear. We examined the molecular composition of LMS by site of origin to better inform future drug development and trial design. Methods: We reviewed 1115 specimens with LMS histology tested by Caris Life Sciences for targeted exome (NextSeq, 592 gene panel), whole exome, and whole transcriptome sequencing (NovaSeq). Specimens were stratified into uLMS, rpLMS (retroperitoneal), and otherLMS (non-uterine/retroperitoneal) subgroups based on tumor origin sites. Genomic data was analyzed for mutations, copy number aberrations, and fusions. RNA expression profiling included evaluation of individual genes and gene set enrichment analysis (GSEA). P-value adjustment performed by the Benjamini-Hochberg procedure. Results: The study cohort was comprised of 62.9% uLMS (n = 701), 14.9% rpLMS (n = 166) and 22.2% otherLMS (n = 248) specimens. Overall, LMS specimens most frequently harbored TP53 (64%, n = 612), ATRX (30%, n = 219), RB1 (22%, n = 156), and MED12 (16%, n = 94) mutations, with these genes accounting for 74.4% (n = 1044) of all observed pathogenic/likely pathogenic mutations. RB1 mutations were significantly less common in uLMS (15%) compared to rpLMS (30%, p < 0.05) and otherLMS (33%, p < 0.01), whereas MED12 mutations were almost exclusive to uLMS (22% vs 1% rpLMS, 3% otherLMS, p < 0.05). MAP2K4 copy number amplification were more common in rpLMS (22%, p < 0.001) and otherLMS (14%, p < 0.182) compared to uLMS (7%), with frequent co-amplification of nearby genes ( FLCN, GID4, SPECC1, GAS7, PER1, and AURKB) located at chr17p11-13. Actionable gene fusions involving ALK (2.1%, n = 11), FGFR1 (0.2%, n = 1), and NTRK1/2 (0.2%, n = 1 each) were rare overall, with similar prevalence across subtypes. Genomic alteration rates were not significantly different between rpLMS and otherLMS subtypes . RNA expression profiling identified significant upregulation of PI3K/AKT/mTOR, DDR, WNT/Beta-Catenin pathway genes in non-uLMS. GSEA indicated several immune-related gene sets were enriched in rpLMS and otherLMS compared to uLMS. Conclusions: Comprehensive molecular profiling suggests that LMS originating from the uterus represents a molecularly distinct disease compared to other primary sites of origin. We identified key genomic patterns which have potential for targeted therapy. These data provide insight for the framework of future clinical trials designed to separate uLMS from non-uLMS histologies, although further subdivision does not appear to be warranted.

11512 Background: Leiomyosarcomas (LMS) have been reported to have immunohistochemical (IHC) and gene expression signatures suggestive of an immune-responsive tumor microenvironment. Despite this, immune checkpoint inhibitors have demonstrated minimal activity in LMS. We examined molecular profiles of LMS specimens from multiple institutions to explore mechanisms of immunotherapy (IO) resistance. Methods: LMS specimens (n = 1115), including 701 uterine (uLMS) and 414 soft tissue site (stLMS) samples, underwent next-generation sequencing (NGS) of DNA (592-gene panel or whole exome) and RNA (whole transcriptome, n = 537) at Caris Life Sciences (Phoenix, AZ). A threshold of 10 mut/Mb was used to identify high tumor mutational burden (TMB-H). IHC was performed for PD-L1 (SP142; 2+|5% positive). Deficient mismatch repair (dMMR)/high microsatellite instability (MSI-H) was tested by IHC and NGS, respectively. RNA expression was analyzed using Gene Set Enrichment Analysis and Microenvironment Cell Populations-counter, with results compared to melanoma (n = 1255) as a representative immunogenic tumor type. P-values were adjusted for multiple hypothesis testing. Results: TMB-H was observed in 3.8% (n = 41) of LMS specimens, with a median of 5 mut/Mb (IQR 3.3-6.7). dMMR/MSI-H was rarely detected (1.5%, n = 17), whereas 8.2% (n = 88) were positive for PD-L1 expression. uLMS and stLMS did not differ in TMB-H (3.4 vs 4.5%, p = 0.277), PD-L1 expression (8.6 vs 7.4%, p = 0.322), or dMMR/MSI-H (2.0 vs 0.7% p = 0.207). stLMS demonstrated upregulation of immune-related gene sets, including interferon γ (p = 0.035) and α (p = 0.033) response, inflammatory response (p = 0.038), interleukin-6/STAT3 signaling (p = 0.030), and TNFα signaling (p = 0.026) compared to uLMS. Immune cell infiltration was increased in stLMS over uLMS, most notably for CD8 T-cell and B-cell abundance ( > 2-fold increase, p < 0.0001). Compared to melanoma, all LMS had lower abundance of CD8 T cells, cytotoxic lymphocytes, and B-cells ( > 2-fold decrease, p < 0.0001). Fibroblasts were more prevalent in LMS relative to melanoma (3.2-fold increase, p < 0.0001). Interestingly, while higher CD8 T-cell infiltration was positively associated with dMMR/MSI-H among LMS specimens (p = 0.032), TMB-H and PD-L1 expression were associated with lower CD8 T-cell infiltration (p < 0.01). Conclusions: Only a small proportion of LMS are TMB-H or MSI-H, suggesting that the neoantigen burden in LMS may be insufficient to promote a robust anti-tumor response, even in the presence of PD-L1 positive tumor cells. Traditional predictive biomarkers of response to IO are unlikely to be useful in LMS. Furthermore, both uLMS and stLMS have an immune microenvironment characterized by a high fibroblast and low T cell abundance relative to melanoma. Future IO trials in LMS should focus on combination therapies that may reverse the observed T-cell exclusion/desmoplastic phenotype.

Bone pain is a common presenting symptom of multiple myeloma (MM) and is frequently treated with opioids in addition to myeloma directed therapy. With improved response and survival with modern myeloma therapy, it is important to reexamine the role of opioids in managing symptomatic myeloma. Patients and Methods:We performed a retrospective analysis of patients with myeloma at Rutgers Cancer Institute of New Jersey (RCINJ) who received an ASCT between January 1, 2012, and December 30, 2017, and who had subsequent followup (a total of 138 patients). We sought information specifically from the visits after induction therapy but prior to ASCT, at 100 days and 1-year post-ASCT follow-up visits. We compared opioid users and non-users in relation to treatment response, co-morbid conditions, and symptoms. We also examined amounts, duration, and odds of continued opioid use. Results:At the time of the first analysis (before transplant), 34.8% of patients were using opioids and opioid use was more frequent in younger patients and, as expected, in patients with bone lesions. At 1 year, 31.9% of patients were still using opioids and continued opioid use was not correlated with disease response. Of the patients using opioids at the time of transplant, 58% either maintained their opioid dose or increased it at 1-year post-transplant. Conclusions:This retrospective analysis shows that despite a small decrease in opioid use over time, opioid use remains frequent in MM patients and is correlated with younger age and bone involvement but not with response to therapy. Over half the patients using opioids at the time of transplant continued or increased opioid use over the following year. With increasing survival in myeloma patients, further attention is required to distinguish cancer pain from chronic pain in cancer patients.

Background: Bone pain is one of the most common presentations of multiple myeloma and nearly all patients have skeletal involvement in the course of disease. Consequently, many patients require narcotics for symptom management at the time of diagnosis but the long term impact of MM treatment on pain control remains uncertain. With the advent of combination therapy for MM with novel agents followed by transplant and then maintenance therapy, clinical response is nearly universal and greater than 30% of patients achieve a serologic complete response. Therefore, we examined the impact of modern myeloma-directed therapy and high response rates on the use of narcotics up to 1 year after transplant in this group of patients. Methods: A retrospective review of data collected from the Rutgers-CINJ database was conducted. All patients who received induction inducing therapy (e.g. bortezomib, lenalidomide and dexamethasone or cyclophosphamide, bortezomib and dexamethasone) followed by high dose melphalan and autologous stem cell transplant (ASCT) and who had adequate post-transplant follow up (at least 100 days) were included. Morphine use was assessed at the time of transplant and at follow-up visits. All opiates (e.g. oxycodone, fentanyl, MS contin, etc.) where converted to morphine equivalents/day (ME/day) and recorded. Treatment responses were determined based on the International Myeloma Working Group Response Criteria. We compared the incidence and amount of narcotic use over time using one-way analysis of variance (ANOVA) and Dunn's multiple-comparison test. Results: 189 patients were included in the analysis. 38% were using opiates at the time of transplant. At 100 days post-transplant 35.5% were using opiates and at 1 year post transplant 30.9% were using opiates (p=0.04) . Average opiate use was 74.1 ME/day (95% CI: 55.2 to 92.9), 69.45 ME/day (95% CI: 50.5 to 88.3), and 70.78 ME/day (95% CI: 43.5 to 98) for each of the aforementioned time points (p=0.088) (Figure 1). For example, 74 ME/day would be equal to approximately 50 mg of Oxycodone daily. 74 patients were active opiate users at the time of transplant (Table 1). Response to myeloma treatment (remission, progression, relapse) was not different in opiate-using patients at the time of transplant or at 100 days and 1 year after transplant (Table 2). Conclusion : Early studies from the 1960's reported on the rapid reduction of bone pain in treatment responsive patients with MM (Hogstrata et al.). Recently, treatment modalities for MM have significantly improved, leading to markedly increased remission rates (>90%), progression-free and overall survival. With dramatically increased serologic responses, one would hypothesize that there would be a decline in pain and a subsequent decrease in opiate use. However, in this retrospective chart review we found that 30% of multiple myeloma patients continued to use opiates following transplant and that ongoing use of opiates appeared to be independent of clinical response. Interestingly, at the time of transplant active opiate users had a CR of 27.2% while the non-opiate using patients had a CR of 13.3%. Although there was a slight decline in the number of opiate users at the 1 year follow up, 33% of opiate users continued at their original level of opiate use and 22% increased their opiate use at 1 year post ASCT. Persistent long term use of opiates is of particular concern given that the survival of patients with MM has significantly improved with the use of novel agents and autologous transplant with an increasing number of patients surviving 10 years or more. In patients who have achieved an excellent response (e.g. serologic CR and negative PET scan), ongoing narcotic use should be addressed at each visit and other advanced pain management techniques should be considered. Disclosures No relevant conflicts of interest to declare.