Citations

Abstract Background. Endothelial progenitor cells (EPCs) are circulating precursors with the capacity to differentiate into endothelial lineage cells through a process known as “vasculogenesis” thus contributing to vessel formation. We studied the role of endothelial progenitor cells in multiple myeloma (MM) pathogenesis. Methods. EPC levels were evaluated in peripheral blood (PB) of patients with smoldering MM (SMM), and active myeloma (MM) and in PB of healthy controls, by using flow-cytometry (CD34+VEGFR2+ cells), and by performing endothelial colony forming assays. EPC levels were studied in PB from transgenic Vk*MYC mice harboring either early MM (smoldering-like stage); or late (active MM-like stage); as well as in mice injected intravenously with either murine MM 5TGM1-turboRFP+ cells or human MM1S-GFP+/luc+ cells. Healthy syngeneic mice were used as controls. GFP-bone marrow (BM) transplantation and sub-cutaneous femur implantation were performed in recipient mice to study EPC BM mobilization (GFP+CD34+VEGFR2 cells) and EPC BM recruitment to the implanted femurs during 5TGM1 MM model progression. Transgenic ID1+/-ID3-/- mice (with a defect in EPC mobilization and differentiation ability) were injected with transplantable Vk*MYC cells and followed for survival. Wild type littermates were used as controls. Similar experiments were performed using transgenic ID1+/-ID3-/- mice transplanted with BM of wild type littermates. Therapeutic activity of DC101 anti-murine VEGFR2 Ab was evaluated in the MM1S human orthotopic xenograft model, using both early and late treatment approaches. Results. EPC levels were significantly increased in PB of MM patients, including SMM, compared to healthy controls (P<0.05). PB mononuclear cells (PBMCs) from SMM and aMM patients showed an increase ability to form both EC-CFUs (P<0.01) and ECFCs compared to those from healthy controls (P<0.05). EPC levels were significantly increased in PB of transgenic Vk*MYC mice at both early and advanced stage of MM development compared to healthy syngenic mice. In orthotopic MM models we found that levels of circulating EPCs increase early after i.v. injection of either human MM1S-GFP+/luc+ cells (1.5 and 2 times higher after 1 week and 2 weeks, respectively) or murine 5TGM1-turboRFP+ MM cells (2.5 and 3 times higher after 2 and 3 weeks, respectively) compared to naïve mice. By coupling GFP-BM transplantation and subcutaneous femur implantation, we generated a new model that allows the study of BM derived-cell trafficking from one site to another of the BM. The levels of BM-derived GFP+ EPC increased early after i.v. injection of 5TGM1-turboRFP+ cells (2 times increase after 2 weeks, P<0.01); also, the percentage of both total GFP+ cells (7.92% versus 2.635%, P<0.05) and GFP+ EPCs (0.22% versus 0.068%, P<0.05) increased in the BM of implanted femurs of tumor cell injected mice compared to controls. Survival of ID1+/-ID3-/- mice was significantly increased compared to that of wild type littermates after injection of MM Vk*MYC cells (62 versus 27 days median survival time, P=0.0005); this survival advantage was lost after wild type BM was transplanted in ID1+/-ID3-/- mice (34 versus 35 days median survival time). In human MM1S orthotopic xenograft model, treatment with anti-murine VEGFR2 DC101 Ab was able to inhibit MM progression when treatment was started early during smoldering like stages, but not when it was started after significant tumor burden (50.5, 41.5 and 40 days median survival time in DC101 early, late and untargeted IgG treated mice respectively) Conclusion. These results show that EPC mediated vasculogenesis is an important pathogenic process that occurs during the early/smoldering MM stage. Knockout mouse experiments confirm that EPCs are essential for MM tumor progression. These results indicate that anti-angiogenic agents could be effective as an early therapeutic intervention in SMM patients. Disclosures Ghobrial: Millennium/Takeda: Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

e15029 Background: ICIs induce durable responses in dMMR CRC pts with overall response rates (ORR) of 30-50%. Even though the loss of expression of any MMR gene predicts ICIs response, it is unknown if ORRs are similar across all MMR genes (MLH1, PMS2, MSH2, and MSH6). In this study, we analyzed the impact of each specific MMR gene loss and clinical characteristics of pts with best response to ICIs. Methods: Pts were eligible if they had confirmed dMMR CRC by IHC or microsatellite instability-high (MSI-H) by PCR, and received ICIs between 01/01/2012 and 10/01/2018 at Winship Cancer Institute of Emory University, Mayo Clinic or Vanderbilt University Medical Center. Due to the pattern of frequent concurrent loss and functional dependency, the groups were categorized as MLH1 ±PMS2 vs. MSH2 ±MSH6. Cox proportional hazard model and Fisher’s exact test were used for the best response and the distribution of variable among the subgroups. Results: A total of 45 pts with dMMR CRC were identified. ORRs in MLH1 ±PMS2 and MSH2 ±MSH6 groups were 68% and 57.1% respectively without statistical difference (Table). Pts with age < 50 and 50-65 years old had better ORRs compared to pts with age >65 (58.3%, 85.7% and 42.1% respectively, P=0.036). Left-sided tumors had a trend toward higher ORRs compared to right-sided tumors (83.3% vs 51.5% P=0.086). Gender and BRAF status were not predictors of response. BRAF mutations were more common in right-sided tumors (29.6% vs 11.1% respectively) and in older patients. Conclusions: Our data suggest that MSI-H CRC pts aged 50-65 treated with ICIs, have improved ORR compared to pts > 65; pts with left-sided tumors have a trend toward improved ORR compared to those with right sided tumors. [Table: see text]

Abstract Citron Rho-interacting serine/threonine kinase (CIT) is a serine/threonine kinase that acts as a key component of the midbody and is essential for cytokinesis. CIT has been reported to be highly expressed in some tumor tissues and to play a role in cancer proliferation; however, the significance of CIT has not been investigated in multiple myeloma (MM). Here, we identified, by protein microarray and immunohistochemistry, that CIT is 1 of the upregulated proteins in the plasma cells of MM patients compared with healthy controls. Analysis of a gene expression profile data set showed that MM patients with high CIT gene expression had significantly worse overall survival compared with MM patients with low CIT gene expression. CIT silencing in MM cell lines induced cytokinesis failure and resulted in decreased MM cell proliferation in vitro and in vivo. TP53 expression was found to be an independent predictor of CIT dependency, with low-TP53 cell lines exhibiting a strong dependency on CIT. This study provides the rationale for CIT being a potential therapeutic target in MM in future trials.

The hereditary spastic paraplegias (HSPs) are a heterogeneous group of disorders characterized by degeneration of the corticospinal and spinocerebellar tracts leading to progressive spasticity. One subtype, spastic paraplegia type 47 (SPG47 or HSP‐AP4B1), is due to bi‐allelic loss‐of‐function mutations in the AP4B1 gene. AP4B1 is a subunit of the adapter protein complex 4 (AP‐4), a heterotetrameric protein complex that regulates the transport of membrane proteins. Since 2011, 11 individuals from six families with AP4B1 mutations have been reported, nine of whom had homozygous mutations and were from consanguineous families. Here we report eight patients with AP4B1‐associated SPG47, the majority born to non‐consanguineous parents and carrying compound heterozygous mutations. Core clinical features in this cohort and previously published patients include neonatal hypotonia that progresses to spasticity, early onset developmental delay with prominent motor delay and severely impaired or absent speech development, episodes of stereotypic laughter, seizures including frequent febrile seizures, thinning of the corpus callosum, and delayed myelination/white matter loss. Given that some of the features of AP‐4 deficiency overlap with those of cerebral palsy, and the discovery of the disorder in non‐consanguineous populations, we believe that AP‐4 deficiency may be more common than previously appreciated.

We characterized the effect of systemic therapy given after portal vein embolization (PVE) and before hepatectomy on hepatic tumor and functional liver remnant (FLR) volumes. All 76 patients who underwent right PVE from 2002–2016 were retrospectively studied. Etiologies included colorectal cancer (n = 44), hepatocellular carcinoma (n = 17), cholangiocarcinoma (n = 10), and other metastases (n = 5). Imaging before and after PVE was assessed. Chart review revealed systemic therapy administration, SNaPshot genetic profiling, and comorbidities. Nine patients received systemic therapy; 67 did not. Tumor volume increased 28% in patients who did not receive and decreased −24% in patients who did receive systemic therapy (p = 0.026), with no difference in FLR growth (28% vs. 34%; p = 0.645). Among 30 patients with genetic profiling, 15 were wild type and 15 had mutations. Mutations were an independent predictor of tumor growth (p = 0.049), but did not impact FLR growth (32% vs. 28%; p = 0.93). Neither cirrhosis, hepatic steatosis, nor diabetes impacted changes in tumor or FLR volume (p > 0.20). Systemic therapy administered after PVE before hepatic lobectomy had no effect on FLR growth; however, it was associated with decreasing tumor volumes. Continuing systemic therapy until hepatectomy may be warranted, particularly in patients with genetic mutations.

Purpose The American College of Surgeons Oncology Group Z1071 trial reported a 12.6% false-negative rate (FNR) for sentinel lymph node (SLN) surgery after neoadjuvant chemotherapy (NAC) in cN1 disease. Patients were not selected for surgery based on response, but a secondary end point was to determine whether axillary ultrasound (AUS) after NAC after fine-needle aspiration cytology can identify abnormal nodes and guide patient selection for SLN surgery. Patients and Methods Patients with T0-4, N1-2, M0 breast cancer underwent AUS after neoadjuvant chemotherapy. AUS images were centrally reviewed and classified as normal or suspicious lymph nodes. AUS findings were tested for association with pathologic nodal status and SLN FNR. The impact of AUS results to select patients for SLN surgery to reduce the FNR was assessed. Results Postchemotherapy AUS images were reviewed for 611 patients. One hundred thirty (71.8%) of 181 AUS-suspicious patients were node positive at surgery compared with 243 (56.5%) of 430 AUS-normal patients (P < .001). Patients with AUS-suspicious nodes had a greater number of positive nodes and greater metastasis size (P < .001). The SLN FNR was not different based on AUS results; however, using a strategy where only patients with normal AUS undergo SLN surgery would potentially reduce the FNR in Z1071 patients with ≥ two SLNs removed from 12.6% to 9.8% when preoperative AUS results are considered as part of SLN surgery. Conclusion AUS is recommended after chemotherapy to guide axillary surgery. An FNR of 9.8% with the combination of AUS and SLN surgery would be acceptable for the adoption of SLN surgery for women with node-positive breast cancer treated with neoadjuvant chemotherapy.

Purpose The seventh edition of the American Joint Committee on Cancer (AJCC) staging system for breast cancer differentiates patients with T1 tumors and lymph node micrometastases (stage IB) from patients with T1 tumors and negative nodes (stage IA). This study was undertaken to determine the utility of the stage IB designation. Patients and Methods The following two cohorts of patients with breast cancer were identified: 3,474 patients treated at The University of Texas MD Anderson Cancer Center from 1993 to 2007 and 4,590 patients from the American College of Surgeons Oncology Group (ACOSOG) Z0010 trial. Clinicopathologic and outcomes data were recorded, and disease was staged according to the seventh edition AJCC staging system. Recurrence-free survival (RFS), disease-specific survival (DSS), and overall survival (OS) were determined using the Kaplan-Meier method and compared using the log-rank test. Results Median follow-up times were 6.1 years and 9.0 years for the MD Anderson Cancer Center and ACOSOG cohorts, respectively. In both cohorts, there were no significant differences between patients with stage IA and stage IB disease in 5- or 10-year RFS, DSS, or OS. Estrogen receptor (ER) status and grade significantly stratified patients with stage I disease with respect to RFS, DSS, and OS. Conclusion Among patients with T1 breast cancer, individuals with micrometastases and those with negative nodes have similar survival outcomes. ER status and grade are better discriminants of survival than the presence of small-volume nodal metastases. In preparing the next edition of the AJCC staging system, consideration should be given to eliminating the stage IB designation and incorporating biologic factors.