Impact of PD-L1 expression on conventional urothelial bladder carcinoma (UBC) genomic alteration (GA) profile

563

Background: Immunohistochemistry (IHC) to determine PD-L1 expression level has been proposed a companion assay related to the approval of immune checkpoint inhibitors in UBC. We hypothesized that the GA profiles would differ between UBC featuring high vs negative PD-L1 expression. Methods: 102 cases of advanced UBC with known PD-L1 expression underwent hybrid-capture based comprehensive genomic profiling to evaluate all classes of GA. Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. Tumor cell (TC) PD-L1 expression was determined by IHC (Dako 22C3). Only PD-L1 high (H) (≥50% TC expression) and negative (N) (0% TC expression) cases were included with PD-L1 Low (1-49% TC expression) cases excluded from this study. Results: Overall, only 2 (8.3%) of the 24 PD-L1H UBC featured CD274 ( PD-L1) amplification (mean 19 copies) and none of 78 PD-L1N had CD274 amp (P =.05). The gender, age was similar in the groups. When compared with the PD-L1H UBC cases, FGFR3 GA were significantly more frequent in the UBC PD-L1N cases (p =.02). Currently “untargetable” GA that were more frequent in the PD-L1H UBC, but did not reach statistical significance, included TP53, TERT and RB1. MTAP loss, a potential target for PRMT5 and MTA2 inhibitors, were 3X more frequent in the PD-L1N UBC. ERBB2 amplification and ERBB3 and PIK3CA short variant (SV) GA were more frequent in the PD-L1N UBC with differences not reaching significance. Other ICPI-associated potential biomarkers, including MSI status, TMB level and GA in PBRM1, STK11 and MDM2 were not significantly different in the groups. For UBC cases where a mutational signature could be determined, 10/12 (83%) of PD-L1H and 21/29 (72%) of PD-L1N UBC featured APOBEC signature; 2 PD-L1N featured MMR signature and 6 PD-L1N UBC featured no dominant signature. Conclusions: PD-L1H and PD-L1N subtypes of UBC differ in their genomic profiles:PD-L1N UBC features greater frequencies of potentially “targetable” GA, including FGFR3, ERBB2, ERBB3 and PIK3CA. PD-L1 IHC may thus not only play a role in the selection of ICPI for advanced UBC but also in designing trials that may combine ICPI with targeted therapies. Limitations include small sample size, possible selection bias and lack of clinical annotation.[Table: see text]

Genomic classification of clinically advanced major genito-urinary cancers (GUca) based on methylthioadenosine phosphorylase (MTAP) genomic loss

164

Background: Novel treatments for clinically advanced GUca including castrate resistant prostate ca (PC), bladder urothelial ca (BUC) and clear cell renal ca (ccRCC) are widely needed. Recently, the targeting of cancer cells with arginine accumulation caused by MTAP loss has emerged as a new synthetic lethality-based anti-cancer program. Methods: 8,436 mCRPC, 2,683 BUC and 841 ccRCC underwent hybrid-capture based comprehensive genomic profiling (CGP) to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. PD-L1 tumor cell expression was determined by IHC (Dako 22C3). Results: 1.3% of PC, 24.2% of BUC and 5.5% of ccRCC featured MTAP loss. There were no significant age or gender differences associated with MTAP loss. CDKN2A/B loss ranged from 94% in ccRCC to > 99% in PC and BUC. The GA/tumor frequencies were similar when CDKN2A/B GA are excluded. In PC, GA in TP53, PTEN and BRCA1 were more frequent, while GA in AR, CDK12, RB1 and BRCA2 were less frequent in cases with MTAP loss. In BUC, GA in TSC1 and FGFR3 were more frequent and GA in RB1and TP53 were less frequent in cases with MTAP loss. In ccRCC, GA in NF2 were more frequent in cases with MTAP loss, while GA in VHL and PBRM1 were less frequent in cases with MTAP loss. “Targetable” kinase GA were rare in all groups, except for FGFR3 GA in MTAP loss BUC. Immunotherapy (IO) putative biomarkers varied among tumors, with MSI-high status less frequent and TMB ≥ 10 mut/Mb more frequent in BUC MTAP-intact than BUC with MTAP loss. PD-L1 expression was similar except for high PD-L1 expression more frequent in MTAP-intact BUC. Conclusions: When compared with PC and ccRCC, the clinical development of novel drugs, such as PRMT5 and MTA2 inhibitors in GUca will likely be focused on BUC given the 24% frequency of MTAP loss in that tumor type. CGP of PC, BUC and ccRCC reveal significant differences in GA in MTAP-intact and tumors with MTAP loss, which may impact future combinatorial clinical trial designs.[Table: see text]

Expanding the use of targeted therapy for urothelial bladder cancer (UBC): Non-FGFR3 receptor tyrosine kinase (RTK) gene rearrangements (ReAr) and fusions (fus)

550

Background: After the regulatory approval of erdafitinib targeting FGFR genomic alterations (GA), molecular profiling and targeted therapy indications may further expand in UBC. We queried a large database of advanced UBC to study the landscape of RTK ReAr and Fus to categorize additional targets beyond FGFR1-3 that have potential to further personalize treatment of this disease. Methods: We analyzed data from 8,233 UBC cases, which underwent hybrid capture-based comprehensive genomic profiling (CGP). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression in tumor cells was assessed by IHC (Dako 22C3). Results: A total of 1,210 (14.7%) UBC featured known and likely large-scale (LS) internal ReAr with 414 (5%) ReAr in RTK genes. The ReAr/fus were distributed among ABL1 (3), ALK (3), BRAF (29), CDK12 (44), CDK8 (1), EGFR (10 ), ERBB2 (3), FGFR1 (2), FGFR2 (16 ), FGFR3 (231), FLT3 (1), MAO2K4 (4), NTRK1 (7 ), NTRK2 (5), NTRK3 (7), RAF1 (31 ), RET (8) and ROS1 (9). LS ReAr were divided into LS ReAr-associated gene deletions (1%), truncations (1%), rearrangements (61%) and fusions (37%). FGFR3 fus accounted for 81% of RTK fus with BRAF and RAF1 both at 2%. The greatest frequencies of kinase ReAr were in CDK12 (29%), FGFR3 (16%), RAF1 (13%) and BRAF (12%). Additional noteworthy ‘targetable’ RTK ReAR and fus included NTRK1-3 (19 cases), ROS1 (9 cases), RET (8 cases) and ALK (1 case). 407 (98.4%) of the RTK ReAr/fus-positive UBC had only 1 RTK ReAr/fus GA and 7 (1.6%) had 2 ReAr ReAr/fus, 6 (85.7%) of which involved FGFR3. Compared with LS ReAR negative UBC, the LS ReAR UBC cases revealed similar gender and age characteristics, MSI status, similar frequencies of TMB ≥ 10 mut/Mb and PD-L1 expression in tumor cells ≥1% and ≥50%. Conclusions: At a 5% frequency, potentially ‘targetable’ RTK gene rearrangements and fusions are a rare but important opportunity to further personalize treatment selection of UBC, including RTK inhibitors, PARP inhibitors ( CDK12) and immunotherapy. This potential for clinical trials supports broader CGP, compared to targeted FGFR sequencing, in order to uncover additional opportunities for precision therapies that have the potential to improve patient outcomes.[Table: see text]

Comprehensive genomic profiling (CGP) of chromophobe renal cell carcinoma (chrRCC) compared with clear cell RCC (ccRCC): Impact of FLCN genomic alteration (GA) status

292

Background: FLCN is a tumor suppressor gene associated with cutaneous hair follicle development. FLCN germline mutations are linked to inherited chrRCC in the Birt-Hogg-Dube (BHD) syndrome. We queried whether clinically sporadic chrRCC featured FLCN mutations by comparing the genomic profiles of chrRCC with ccRCC. Methods: 108 chrRCC and 2110 ccRCC underwent hybrid-capture based comprehensive genomic profiling (CGP) to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results: Patients (pts) with chrRCC were more frequently female and younger than pts with ccRCC p <.0001). None of the submitted clinical records in the chrRCC cases listed signs of BHD syndrome. FLCN GA were identified in only 2.3% of the ccRCC cases with 37% of the GA predicted to be germline. chrRCC did not reveal somatic or germline FLCN GA. GA/tumor were slightly higher in ccRCC vs chrRCC (3.6 vs 2.4; NS). GA more frequent in chrRCC included TP53, RB1 and PTEN. GA more frequent in the ccRCC included VHL, BAP1, PBRM1, SETD2, CDKN2A/B, ARID1A, NF2, PIK3CA and TERT. Putative biomarkers of immune checkpoint inhibitor (ICPI) response were infrequent in both groups with only a slightly higher, but still low, mean TMB in ccRCC vs chrRCC cases. IHC revealed moderate PD-L1 expression at low and minimal PD-L1 expression at high staining level, which was slightly increased in the chrRCC group. Conclusions: FLCN mutations that are associated with the familial incidence of chrRCC were not associated with sporadic chrRCC. Sporadic chrRCC has substantially different genomic profile from ccRCC and may harbor a few ‘targetable’ GA. The prediction of response to ICPI in RCC remains challenging with chrRCC featuring slightly higher PD-L1 expression and ccRCC featuring higher PBRM1 GA and higher TMB.[Table: see text]

Association of RB1 mutational status with overall genomic landscape in neuroendocrine prostate cancer (NEPC)

156

Background: NEPC is a high-grade aggressive form of prostate cancer. We queried whether RB1 mutation status would impact the genomic features of NEPC. We hypothesized that there would be differences in GA frequencies in RB1 mutated vs non mutated cases. Methods: From a series of 13,496 cases of clinically advanced PC, 415 (3.1%) histologically defined NEPC were sequenced using a hybrid capture-based FDA-approved clinical genomic profiling (CGP) assay to detect all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on 0.8 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 95 loci. PD-L1 expression was determined by IHC (Dako 22C3) with low tumor cell positive staining 1-49% and high staining ≥50% expression. Results: 253 (61%) of NEPC feature GA in RB1 (RB1 mut+). This contrasts with a 5.8% frequency of RB1 GA in the non-NEPC (P <.0001). The RB1 mut+ NEPC featured a slightly greater number of driver GA/tumor than the RB1 mut- NEPC (5.1 vs 4.2). Age and TMPRSS2-ERG fusion frequency were similar between the groups. RB1 Mut- NEPC was associated with significantly higher amplifications (amp) and total GA in AR compared to RB1 mut+ NEPC. RB1 mut+ NEPC featured significantly greater frequency of PTEN GA. GA frequencies in targetable kinases and DNA repair GA including BRCA1/2 and ATM linked to PARP inhibitor (PARPi) response were similar in both groups. For potential immune-oncology (IO) biomarkers, RB1 Mut+ NEPC featured significantly greater frequency of low positive PD-L1 expression and lower frequencies of MDM2 and CDK12 GA. CD274 ( PD-L1) amplification, MSI-high status and cases with TMB ≥10 mut/Mb were very uncommon in both groups. Conclusions: In NEPC, the presence of RB1 mutation is associated with various GA that may have clinical relevance. Limitations include possible selection and confounding biases, and lack of clinical annotation. Further study of RB1 status as a guide of trial designs on therapy selection for men with NEPC is warranted.[Table: see text]

Double PIK3CA Alterations and Parallel Evolution in Colorectal Cancers

OBJECTIVES

To demonstrate clinicopathologic features and evaluate the clonality of double PIK3CA alterations in colorectal cancers (CRCs).

METHODS

Clonality was examined in 13 CRCs with double PIK3CA alterations (1.7% of CRCs or 9.6% of PIK3CA-mutated CRCs). Multiregional analyses were performed to confirm subclonal PIK3CA alterations.

RESULTS

PIK3CA alterations were detected within exon 9 (51%), exon 20 (23%), exon 1 (15%), and exon 7 (6.0%). CRCs with exon 7 alterations showed a significantly higher incidence of double PIK3CA alterations. Most double PIK3CA alterations consisted of a hotpsot alteration and an uncommon alteration; they were often clonal and present within a single tumor population. Multiregional analyses of CRCs with predicted subclonal double-alterations revealed multiclonal CRCs with divergent PIK3CA variant status originating from a common APC- and KRAS-mutated founder lineage of adenoma.

CONCLUSIONS

The findings supported multiclonal CRCs resulting from parallel evolution during the progression from adenoma to adenocarcinoma within the mitogen-activated protein kinase pathway, as previously demonstrated, or the mammalian target of rapamycin pathway. Further studies are warranted to elucidate clinical significance and potential targeted therapy for CRC patients with double PIK3CA alterations and impacts on clinical decision-making in patients with multiclonal CRCs harboring divergent PIK3CA mutational status.

Genomic classification of clinically advanced pancreatic ductal adenocarcinoma (PDAC) based on methylthioadenosine phosphorylase (MTAP) genomic loss (MTAP loss)

604

Background: MTAP loss is represented across a wide variety of cancer types including PDAC and is an emerging target for synthetic lethality-based cancer therapies. Preclinically, MTAP loss leads to the accumulation of 2-methylthioadenosine, reduced protein arginine N-methyltransferase 5 (PRMT5) methylation activity and increased vulnerability to targeting of the methionine adenosyltransferase IIα (MAT2A)/ PRMT5 axis. In addition, 9p21 loss, homozygous co-deletion of MTAP/CDKN2A or homozygous deletion of either gene have been associated with an immunologically “cold” tumor microenvironment, primary resistance to anti PD(L)1 immunotherapy (IO) and poor prognosis phenotype (Han G, Nat Commun 2021). We investigated concurrent mutations and immune biomarkers in clinical PDAC samples with MTAP-loss versus -intact status. Methods: From a series of 177705 consecutive cases, we performed comprehensive genomic profiling on 9423 cases of PDAC using an FDA-approved assay (F1CDx) to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression was determined by immunohistochemistry (Dako 22C3). Furthermore, we correlated pertinent findings within a database of 16558 cases of clinically advanced cancer with MTAP loss. Results: 2003 (21.3%) of 9423 PDAC demonstrated MTAP-loss. Similar gender, age and number of GA per tumor were observed between MTAP-loss and -intact groups. Frequencies of TP53, CDKN2A/B, SMAD4, PTEN and ARID1A were significantly higher in MTAP-loss PDAC. However, previously-described biomarkers of IO efficacy (MSI, TMB, CD274 amplification and PD-L1 expression) and resistance ( STK11, KEAP1 and MDM2) were infrequent and similar in both groups. The frequencies of other potentially targetable GA including BRCA1/2, ATM, KRAS G12C, ERBB2, BRAF, FGFR1, NF1 and PIK3CA were also infrequent and similar in both groups of PDAC patients. Amongst a database of 16558 cases of clinically advanced cancer with MTAP loss, 1538 (9.3%) featured co-alterations in MTAP and SMAD4. 52% of the MTAP/SMAD4 co-altered cases were PDAC. Conclusions: MTAP loss is associated with a distinctive concurrent genomic profile in PDAC and represents a potential new synthetic lethality-based opportunity for treatment with PRMT5 and MAT2A inhibitors. Furthermore, MTAP loss may represent an independent negative predictive biomarker for immune checkpoint inhibition in PDAC.[Table: see text]

IDH1 and IDH2 Mutations in Colorectal Cancers

OBJECTIVES

To elucidate clinicopathologic and molecular characteristics of IDH1 and IDH2 (IDH1/2) mutations in colorectal cancers (CRCs).

METHODS

We evaluated IDH1/2 mutations in 1,623 CRCs using a next-generation sequencing assay.

RESULTS

IDH1/2 mutations, predominantly IDH1 p.R132C, were detected in 15 (0.9%) CRCs and in 5 (3.0%) of 167 BRAF p.V600E-mutated CRCs. Three IDH1/2-mutated CRCs were associated with inflammatory bowel disease. They were significantly associated with old age, mucinous or signet ring cell adenocarcinoma, and high-grade histomorphology. Concordance of variant allele frequency between IDH1/2 mutants and other trunk drivers in CRCs and presence of IDH1/2 mutation in the adenoma and early adenocarcinoma indicated IDH1/2 mutations could be trunk drivers suitable for targeted therapy.

CONCLUSIONS

IDH1/2 mutations in CRCs were uncommon but enriched in BRAF p.V600E-mutated CRCs and perhaps colitis-associated CRCs. Further studies on IDH1/2-mutated CRCs are needed to clarify their clinicopathologic features and implications for targeted therapy.

Necroptosis in spontaneously-mutated hematopoietic cells induces autoimmune bone marrow failure in mice

Acquired aplastic anemia is an autoimmune-mediated bone marrow failure syndrome. The mechanism by which such an autoimmune reaction is initiated is unknown. Whether and how the genetic lesions detected in patients cause autoimmune bone marrow failure have not yet been determined. We found that mice with spontaneous deletion of the TGFβ-activated kinase-1 gene in a small subset of hematopoietic cells developed bone marrow failure which resembled the clinical manifestations of acquired aplastic anemia patients. Bone marrow failure in such mice could be reversed by depletion of CD4⁺ T lymphocytes or blocked by knockout of interferon-γ, suggesting a Th1-cell-mediated autoimmune mechanism. The onset and progression of bone marrow failure in such mice were significantly accelerated by the inactivation of tumor necrosis factor-α signaling. Tumor necrosis factor-α restricts autoimmune bone marrow failure by inhibiting type-1 T-cell responses and maintaining the function of myeloid-derived suppressor cells. Furthermore, we determined that necroptosis among a small subset of mutant hematopoietic cells is the cause of autoimmune bone marrow failure because such bone marrow failure can be prevented by deletion of receptor interacting protein kinase-3 Our study suggests a novel mechanism to explain the pathogenesis of autoimmune bone marrow failure.

Nuclear size measurement for distinguishing urothelial carcinomas from reactive urothelium on tissue sections

Background

Pathological diagnosis of urothelial carcinoma (UC) is primarily based on cytological atypia. It has previously been shown that high-grade (HG) UC, particularly UC in situ cells (CIS), can be over five times the size of a lymphocyte. However, this has not been demonstrated in comparison to reactive urothelium. The objective of this study was to empirically compare the difference in nuclear size of UC cells with reactive urothelial cells.

Methods

Using CellSens imaging software, we measured urothelial nuclear length (l) and width (w) on digital images of H&E sections. The area (a) of a nucleus was calculated based on the oval shape of most urothelial cells. Lymphocytes were measured to calculate normalized urothelial linear and area ratios.

Results

A total of 1085 urothelial cell nuclei from 60 cases were measured from reactive urothelium, low grade (LG) UC, HG UC and CIS. CIS nuclei were found to have an a 2.75 times larger than reactive nuclei (p < 0.001). A nuclear size cut-off of 11 um for l and 7 um for w was found to be sensitive [98.09 % (95 % CI: 95.60–99.38 %) and 89.31 % (95 % CI: 83.6–91.82 %) for l and w, respectively] and specific [92.60 % (95 % CI: 87.13–95.82 %) and 85.71 % (95 % CI: 79.49–90.63 %) for l and w, respectively] for distinguishing CIS from reactive atypia.

Conclusions

Nuclear morphometry can be used to differentiate CIS from reactive atypia. A l over 11 um and a w over 7 um and is highly sensitive and specific for CIS compared to reactive urothelium. This difference in nuclear size may be used as a tool for differentiating the flat urothelial lesions from reactive urothelium in daily practice.

Constitutive Expression of a Dominant-Negative TGF-β Type II Receptor in the Posterior Left Atrium Leads to Beneficial Remodeling of Atrial Fibrillation Substrate

RATIONALE

Fibrosis is an important structural contributor to formation of atrial fibrillation (AF) substrate in heart failure. Transforming growth factor-β (TGF-β) signaling is thought to be intricately involved in creation of atrial fibrosis.

OBJECTIVE

We hypothesized that gene-based expression of dominant-negative type II TGF-β receptor (TGF-β-RII-DN) in the posterior left atrium in a canine heart failure model will sufficiently attenuate fibrosis-induced changes in atrial conduction and restitution to decrease AF. Because AF electrograms are thought to reflect AF substrate, we further hypothesized that TGF-β-RII-DN would lead to increased fractionation and decreased organization of AF electrograms.

METHODS AND RESULTS

Twenty-one dogs underwent injection+electroporation in the posterior left atrium of plasmid expressing a dominant-negative TGF-β type II receptor (pUBc-TGFβ-DN-RII; n=9) or control vector (pUBc-LacZ; n=12), followed by 3 to 4 weeks of right ventricular tachypacing (240 bpm). Compared with controls, dogs treated with pUBC-TGFβ-DN-RII demonstrated an attenuated increase in conduction inhomogeneity, flattening of restitution slope and decreased duration of induced AF, with AF electrograms being more fractionated and less organized in pUBc-TGFβ-DN-RII versus pUBc-LacZ dogs. Tissue analysis revealed a significant decrease in replacement/interstitial fibrosis, p-SMAD2/3 and p-ERK1/2.

CONCLUSIONS

Targeted gene-based reduction of TGF-β signaling in the posterior left atrium-with resulting decrease in replacement fibrosis-led to beneficial remodeling of both conduction and restitution characteristics of the posterior left atrium, translating into a decrease in AF and increased complexity of AF electrograms. In addition to providing mechanistic insights, this data may have important diagnostic and therapeutic implications for AF.

Abstract P5-08-21: Expression of EZH2 and its downstream effectors pEZH2 and H3K27 in pregnancy associated breast cancer (PABC)

Background: Pregnancy associated breast cancer (PABC) arises during or after pregnancy, is typically triple negative, and is associated with a poor prognosis. Enhancer of Zeste Homolog 2 (EZH2), a core protein of the polycomb-repressive complex, plays a vital role in the epigenetic maintenance of histone H3 lysine (H3K27) repressive chromatin mark and has been found to be aberrantly expressed in various cancers including the breast. EZH2 is involved in stem cell renewal and is involved the initiation, progression and maintenance of cancer cells. EZH2 has been reported to be highly expressed in triple negative breast cancers and to be associated with poor prognosis. In this study, we assessed expression of EZH2 and its downstream markers phosphorylated EZH2 (pEZH2) and H3K27 and correlated their expression with clinicopathologic characteristics in this aggressive type of breast carcinoma.

Design: 23 patients diagnosed with PABC within 2 years of pregnancy (mean age=35.8, range=26-48) and control age-/stage-matched nulliparous women (mean age=37.5, range=29-51) were evaluated. Slides were reviewed and pathologic tumor characteristics were noted. Immunohistochemical stains for EZH2, pEZH2, H3K27 and the cancer stem cell marker ALDH1 were performed on 23 PABC and 15 control cases. Extent (1=1-25% positive tumor cells, 2=26-50%, 3=51-75% or 4=76-100%) and intensity (1=weak, 2=moderate or 3=strong) of staining were assessed. A composite score (CS) was calculated by multiplying the extent by intensity (range=0-9; weak=1-3; moderate=4-6 and strong=7-9).

Results: PABCs were more likely than controls to have moderate to strong immunoreactivity for EZH2 (69.6% vs. 33.3%, p=0.04). All PABC and control cases expressed EZH2 and pEZH2, while 60.9% of PABC and 40% of control cases expressed H3K27. Within the PABC group, moderate to strong EZH2 expression was seen more frequently in grade 3 tumors (86.7% in grade 3 tumors vs. 37.5% in grades 1-2, p=0.03). Of interest, all triple negative (TN) PABC cases had moderate to strong EZH2 (100% vs. 43.8%, p=0.02). All five PABC cases with the strongest EZH2 (CS=9) were grade 3 tumors (3 TN, 1 HER2+ and 1 luminal B), 60% of which had positive lymph node metastasis. Although 83.3% of ALDH1+ cases also had moderate to strong EZH2, no significant correlation was observed.

Conclusions: 1. PABCs express EZH2 and pEZH2 consistently. 2. PABCs are more likely than controls to have moderate to strong immunoreactivity for EZH2. 3. Within the PABC group, all triple negative tumors and the majority of grade 3 tumors have high EZH2 expression. 4. PABC cases with the strongest EZH2 are grade 3 tumors that have positive lymph nodes. Increased expression of EZH2 in PABC may contribute to the poor prognosis in these cases. Our findings add to the understanding of the molecular pathways that operate in different subtypes of breast carcinomas.

Citation Format: Blanco Jr LZ, Parini V, Dhamne SA, Siziopikou KP. Expression of EZH2 and its downstream effectors pEZH2 and H3K27 in pregnancy associated breast cancer (PABC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-21.

A randomized phase II presurgical trial of transdermal 4-hydroxytamoxifen gel versus oral tamoxifen in women with ductal carcinoma in situ of the breast

PURPOSE

Local transdermal therapy to the breast may achieve effective target-organ drug delivery, while diminishing systemic effects. We conducted a randomized, double-blind, placebo-controlled phase II trial comparing transdermal 4-hydroxytamoxifen gel (4-OHT) to oral tamoxifen (oral-T) in women with ductal carcinoma in situ (DCIS).

METHODS

Twenty-seven pre- and postmenopausal women were randomized to 4-OHT (4 mg/day) or oral-T (20 mg/day) for 6 to 10 weeks before surgery. Plasma, nipple aspirate fluid, and breast adipose tissue concentrations of tamoxifen and its major metabolites were determined by liquid chromatography/tandem mass spectrometry. The primary endpoint was Ki67 labeling in DCIS lesions, measured by immunohistochemistry. In plasma, insulin-like growth factor-1 (IGFI), sex hormone-binding globulin (SHBG), and coagulation protein concentrations were determined.

RESULTS

Posttherapy Ki67 decreased by 3.4% in the 4-OHT and 5.1% in the oral-T group (P ≤ 0.03 in both, between-group P = 0. 99). Mean plasma 4-OHT was 0.2 and 1.1 ng/mL in 4-OHT and oral groups, respectively (P = 0.0003), whereas mean breast adipose tissue concentrations of 4-OHT were 5.8 ng/g in the 4-OHT group and 5.4 ng/g in the oral group (P = 0.88). There were significant increases in plasma SHBG, factor VIII, and von Willebrand factor and a significant decrease in plasma IGFI with oral-T, but not with 4-OHT. The incidence of hot flashes was similar in both groups.

CONCLUSIONS

The antiproliferative effect of 4-OHT gel applied to breast skin was similar to that of oral-T, but effects on endocrine and coagulation parameters were reduced. These findings support the further evaluation of local transdermal therapy for DCIS and breast cancer prevention.

Abstract 1985: PBX1 regulated lipid metabolism gene expression and epithelial-mesenchymal transition independent of estrogen receptor

Introduction: Pre-B-cell leukemia homeobox-1 (PBX1) is a member of the three amino acid loop extension (TALE) family of homeodomain proteins that bind to DNA and regulate gene transcription by forming heterodimeric transcription complexes with Meis and Prep1. PBX1 is involved in cell fate determination during organogenesis and contributes to oncogenic activity in breast cancer. As a pioneer factor, PBX1 was found to drive ER signaling in ER+ breast cancer by remodeling the chromatin and increasing DNA accessibility. But the role of PBX1 in benign breast and ER- cancer cells is not clear. In our previous studies, we identified and validated that the expression of a set of lipid metabolism genes was higher in the contralateral breast of ER- tumor. Bioinformatic analysis on lipid metabolism gene promoter regions and revealed that PBX1 may act as a potential transcription factor to co-regulate those genes. In this study, we further investigate the function of PBX1 in ER- cells.

Methods: Among the ER- cell lines, we infected cell lines expressing low endogenous PBX1 (MCF10A and MDA-MB-231) with PBX1 gene in lentiviral vector. We also infected cell lines expressing high endogenous PBX1 (MDA-MB-453 and SK-BR-3) with PBX1-shRNA to knockdown PBX1. The expression of lipid metabolism genes was detected by qRT-PCR. Markers for epithelial-to-mesenchymal transition (EMT) including E-cadherin, vimentin, β-catenin and α-SMA were detected using Western blot. The effects of overexpression or knock-down of PBX1 on proliferation, migration, and invasion were measured using IncuCyte live cell imaging system. The expression of PBX1 protein was measured in benign contralateral breast and in the matching tumor using mmnunohistochemistry.

Results: Over-expression of PBX1 in ER- cell lines (MCF10A and MDA-MB-231) up-regulated lipid metabolism genes and promoted cell migration and invasion by inducing EMT (increased vimentin and decreased E-cadherin and β-catenin). In contrast, knocking-down PBX1 using shRNA in ER- cell lines (MDA-MB-453 and SK-BR-3) suppressed lipid metabolism gene expression. PBX1 was more highly expressed in benign tissues associated with ER- tumors compared to ER+ tumors. In tumor tissue, on the contrary, ER+ tumors shower higher PBX1 expression levels than ER- tumors.

Conclusion: PBX1 is a master regulator of lipid metabolism genes. PBX1 promoted cell migration and invasion by inducing EMT. PBX1 may play different roles and interact with different co-factors in ER+ tumors and in benign tissues associated with ER- tumors.

Citation Format: Ali Shidfar, Liannian Liu, Vamsi Parini, MiRan Choi, David Ivancic, Megan E. Sullivan, Demirkan B. Gursel, Seema A. Khan, Jun Wang. PBX1 regulated lipid metabolism gene expression and epithelial-mesenchymal transition independent of estrogen receptor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1985. doi:10.1158/1538-7445.AM2015-1985

Abstract 4913: Development of Fe3O4@TiO2 core-shell nanocomposites as radiosensitizers

Purpose: To test in vivo, in a rabbit VX2 liver cancer model, a nanocomposite made with Fe3O4 core and TiO2 shell as a possible radiosensitization agent.

Methods: This study was approved by the institutional ACUC. Rabbits were implanted in liver with pairs of VX2 tumors distantly enough to allow irradiation of only one of the two tumors. The tumors were allowed to grow until clearly detectable by magnetic resonance imaging, followed by Computed Tomography (CT) simulation to identify and contour the tumors. Each rabbit was anesthetized, and immobilized in supine position. Isocenter was placed during the CT simulation and the rabbit was tattooed. After the CT, each rabbit was injected with nanoparticles and put under observation until recovery. The core-shell nanoparticles were surface covered with glucose (glut-NPs) and delivered intravenously to 6 rabbits. A radiation oncologist contoured the target volumes. The gross target volume included a hepatic tumor in one lobe; 1 - 3 mm expansion was done to create the clinical target volume and another 1-2 mm expansion to create the planning target volume (PTV). The control hepatic tumor was contoured and the treatment plan objective was to deliver more than 95% of the prescribed dose to the PTV while sparing the control tumor. A certified radiation physicist created the treatment plan. Dose Volume Histograms were created and the radiation oncologist approved the plan. Irradiation usually utilized 2 - 3 beams, delivering 2 Gy as a single fraction using Linear Accelerator. All 6 rabbits treated with nanoparticles the day before (14-18h previously) and 3 radiation-only (not glut-NPs treated) animals were irradiated so that only one of the tumors received radiation. The animals were terminated 3 days after irradiation and the tumors were harvested. Several view-fields with at 3-10 x 103 cells were automatically scored using the NanoZoomer and percentage of Ki67 positive cells, as a marker of proliferation was determined in each tumor. TUNEL assay was done as well.

Results: In each rabbit the larger tumor of the pair was irradiated. In no-NP treated animals that led to the fact that irradiated tumors at 3 days after irradiation generally still had greater number of proliferating cells than the non-irradiated tumor sections. Conversely, in glut-NPs treated rabbits, irradiation led to a decrease of Ki-67 positive cells compared to the paired non-irradiated glut-NPs treated tumors. Three-day time-point was better suited for evaluation of tumor proliferation changes. TUNEL analysis showed higher apoptotic cell numbers in glut-NPs treated tumors (p=0.049). Combination of radiation with glut-NP treatment showed only a mild trend for increased apoptosis compared to non-irradiated glut-NPs treated tumors, this trend was not statistically significant (p=0.53).

Conclusion: These data suggest that the glut-NPs show a considerable promise for radiosensitization.

Note: This abstract was not presented at the meeting.

Citation Format: Tamer Refaat, Derek West, kathleen R. Harris, Vamsi Parini, William Liu, Beau Wanzer, Lydia Finney, Andrew C. Larson, Jonathan Bautista, Vythialinga Sathiaseelan, Bharat Mittal, Tatjana Paunesku, Gayle Woloschak. Development of Fe3O4@TiO2 core-shell nanocomposites as radiosensitizers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4913. doi:10.1158/1538-7445.AM2014-4913

Lung transplantation in patients 60 years and older: results, complications, and outcomes

BACKGROUND

Advanced recipient age is reported to negatively affect survival after lung transplantation (LTX). We hypothesized that LTX in patients aged > or = 60 years could be performed with acceptable outcomes.

METHODS

We identified 182 consecutive LTX recipients from 1995 to 2005. Outcomes were analyzed and survival compared with results in recipients aged < 60, as well as with United Network for Organ Sharing (UNOS) registry outcomes for the same age and study period. Actuarial survivals were calculated by the Kaplan-Meier method.

RESULTS

During the study period, 29% (52/182) of LTX recipients were > or = 60 years old (range, 60 to 69 years). Median follow-up was 2.9 years (range, 0 to 10 years). All patients but one received a single lung. Indications included chronic obstructive pulmonary disease in 63% (33/52), idiopathic pulmonary fibrosis in 27% (14/52), and other in 10% (5/52). In-hospital mortality was 12% (6/52) for those aged > or = 60 compared with 7% (9/130) for those aged < 60 (p = NS). Complications included reoperation in 10% (5/52), requirement for extracorporeal membrane oxygenation in 6% (3/52), renal failure in 12% (6/52), and stroke in 4% (2/52). Actuarial survivals at 30 days, and 1, 3, and 5 years were 90% (82, 98), 86% (76, 96), 71% (56, 85), and 55% (37, 73), respectively. No significant difference in survival was observed between age cohorts for our institutional data by Kaplan-Meier analysis (p = 0.34) or by Cox proportional hazard model (p = 0.15). A significant survival advantage was noted for our institution compared with UNOS for this cohort (p = 0.018).

CONCLUSIONS

In carefully selected recipients > or = 60 years of age, LTX offers acceptable outcomes and survival.

Human exposure to space radiation: role of primary and secondary particles

Human exposure to space radiation implies two kinds of risk, both stochastic and deterministic. Shielding optimisation therefore represents a crucial goal for long-term missions, especially in deep space. In this context, the use of radiation transport codes coupled with anthropomorphic phantoms allows to simulate typical radiation exposures for astronauts behind different shielding, and to calculate doses to different organs. In this work, the FLUKA Monte Carlo code and two phantoms, a mathematical model and a voxel model, were used, taking the Galactic Cosmic Rays (GCR) spectra from the model of Badhwar and O'Neill. The time integral spectral proton fluence of the August 1972 Solar Particle Event (SPE) was represented by an exponential function. For each aluminium shield thickness, besides total doses the contributions from primary and secondary particles for different organs and tissues were calculated separately. More specifically, organ-averaged absorbed doses, dose equivalents and a form of 'biological dose', defined on the basis of initial (clustered) DNA damage, were calculated. As expected, the SPE doses dramatically decreased with increasing shielding, and doses in internal organs were lower than in skin. The contribution of secondary particles to SPE doses was almost negligible; however it is of note that, at high shielding (10 g cm(-2)), most of the secondaries are neutrons. GCR organ doses remained roughly constant with increasing Al shielding. In contrast to SPE results, for the case of cosmic rays, secondary particles accounted for a significant fraction of the total dose.

Outcome of assisted reproductive technologies after different embryo transfer strategies

The outcomes of 1028 assisted reproductive technology cycles were studied retrospectively, considering two different periods of embryo transfer. In the first period, 262 cycles in women < 36 years old were studied, in which three embryos were transferred, followed by 157 cycles in women > or = 36 years, in which four embryos were transferred. In the second period, 332 cycles were evaluated in women < 36 years and 277 cycles in women > or = 36 years old, reducing the number of embryos transferred to two and three respectively. Embryos were only scored morphologically, and the best embryos were chosen for transfer. In the first period, in women < 36 years old, a clinical pregnancy rate of 55.7% was achieved, compared with 42.5% in the second period (P < 0.01). In women > or = 36 years old, the first period of embryo transfer showed a clinical pregnancy rate of 39.5%, compared with 28.5% in the second period (P < 0.01). The number of twin pregnancies in the three groups of patients in whom one to four embryos were transferred was not significantly different (24.2, 28.4, 24.8%). It is concluded that even with the biases induced by a retrospective study, the reduction in the number of embryos transferred, from three to two in women < 36 years of age, and from four to three in women > or = 36 years of age, without any selection other than pre-transfer morphological score, adversely affects the outcome of treatment, without a significant reduction in twin gestation rate. Other strategies are to be implemented in gametes and embryo selection, and patients must be aware that, even with a reduction in pregnancy rate, the goal is to achieve a high cumulative pregnancy rate, reducing the complications induced by multiple pregnancies.