Computational extraction and analysis of de-identified medical records to characterize hyperammonemia in patients with fibrolamellar carcinoma (FLC)

e16169

Background: Rare cancers including FLC make up 25% of adult tumors, but are difficult to study due to low incidence and incomplete case identification. FLC occurs in adolescents and young adults without liver dysfunction. Hyperammonemia has been frequently reported in FLC patients, but is poorly understood. Methods: Data from three clinical trials allowed us to establish the incidence of hyperammonemia (serum ammonia value > 75 µmol/L) in FLC. In these studies, FLC patients received everolimus, estrogen deprivation therapy (EDT) with leuprolide + letrozole or everolimus + EDT (Oncologist. 2020 25(11):925-e1603), ENMD-2076 (Oncologist. 2020 25(12):e1837-e1845), or neratinib (J Clin Oncol 39, 2021 (suppl 3; abstr 310); ammonia was tested prospectively in the latter two studies. To assess impacts of cancer therapy or liver dysfunction, we studied hyperammonemia in FLC and non-FLC patients at UCSF in parallel. Using Natural Language Processing (NLP) of pathology reports and oncology notes from > 2300 liver cancer patients from the last 12 years of UCSF records, we identified a cohort of patients with FLC, contrasting their laboratory data to all UCSF patients with ammonia testing for the last 10 years. We used leiden clustering and umap dimensionality reduction to contrast FLC and other patients to assess the clinical context of hyperammonemia. Results: Data from the 3 trials showed hyperammonemia in 10 of 32 (31.3%) FLC patients during study participation, independent of the therapy received. These patients exhibited hyperammonemia with varying levels, and at different points in their treatment. NLP identified 37 patients with FLC ( < 0.1% of liver cancer patients), with 33% showing hyperammonemia. Across all UCSF patients, we found 24,000 independent visits where ammonia was tested, with > 2400 demonstrating hyperammonemia. Using leidan clustering on all encounters with ammonia > 75 µmol/L, we found distinct subsets of hyperammonemia corresponding to known metabolic and physiologic processes (e.g., fulminant liver failure, tumor lysis syndrome, etc). FLC patients clustered separately from hepatocellular carcinoma patients with hyperammonemic encephalopathy due to cirrhosis. Conclusions: NLP of large EMRs is a valuable tool to study FLC, a rare cancer. Herein, we have defined hyperammonemia as a frequent event in FLC, not directly linked to hepatic dysfunction or individual therapies. Further investigation may determine whether hyperammonemia is related to FLC tumor biology.

Evaluation of neratinib (N), pembrolizumab (P), everolimus (E), and nivolumab (V) in patients (pts) with fibrolamellar carcinoma (FLC)

310

Background: FLC, a rare liver cancer of young adults, has no effective systemic therapies. Surgical resection is used extensively with non-curative intent. FLC is associated with a DNAJB1- PRKACA chimeric transcript that produces a fusion protein with retained kinase activity and increased expression of several oncogenic signaling pathways including, but not limited to, HER2 ( ERBB2). Methods: N (240 mg oral daily) was studied in FLC pts in the SUMMIT study (NCT01953926); and later under compassionate use for N-based combinations (combo): P (2 mg/kg q3w), E (7.5 mg daily), and V (240 mg q2w) in doublet or triplet regimens. Eligible pts: ≥12y; histologically confirmed FLC; adequate organ function; any number of prior therapies. Primary endpoint: objective response rate (ORR; RECIST v1.1). Secondary endpoints: duration of response; clinical benefit rate (CBR); safety (CTCAE v4.0); somatic and germline sequencing (MSK IMPACT). Results: As of 03-Sep-2020, 15 pretreated pts received N in SUMMIT (confirmed ORR 0%; CBR 13%). Efficacy data for 5 pts from SUMMIT and 2 more pts receiving combo under compassionate use (4 male, 3 female, median age 26 years, median 0 [range 0–4] prior systemic therapies) are in shown in the table. The most common adverse events (AE) with single-agent N (n = 5) were diarrhea (grade 1 80%; grade 2 20%) and nausea (grade 1 60%); other AEs were grade ≤1 in ≤20% of pts. Conclusions: N monotherapy had limited benefit as a single agent in FLC pts. Several case studies evaluating N-based combo with checkpoint inhibitors administered under compassionate use demonstrated that NP led to 1 PR, and the triplet of NPE to prolonged SD. These are case-limited observations but are critical and worth evaluating further in upcoming clinical trials given the continued lack of a standard of care therapy for pts with FLC. Clinical trial information: NCT01953926. [Table: see text]

A novel preclinical model of cholangiocarcinoma based on human aberrant FBXW7 expression

e15624

Background: Pre-clinical models that mimic human genetic events occurring in intrahepatic cholangiocarcinoma (iCCA) are limited. The ubiquitin ligase F-box and WD repeat domain-containing 7 (FBXW7) is recognized as a tumor suppressor in many cancer types. Methods: Firstly, we determined the FBXW7 mutation frequency (n = 120) and mRNA expression (n = 87) in a collection of human iCCA. Based on the preliminary findings in human data, we generated a mouse model by hydrodynamic tail vein injection of activated/myristylated (myr-)AKT with Fbxw7ΔF, a dominant negative form of Fbxw7. Subsequently, we investigated the role of established targets of Fbxw7, namely Notch2, Yap, and c-Myc in this novel mouse model and in human CCA cell lines. Results: FBXW7 mRNA expression is almost ubiquitously downregulated (71/82; 86.6%) in human iCCA specimens, while only 0.8% of samples showed FBXW7 somatic mutations. In vivo, co-expression of AKT and Fbxw7ΔF triggered the development of iCCA lesions and mice were euthanized by 15 weeks post-injection due to high tumor burden. At the molecular level, a strong induction of FBXW7 canonical targets, including Yap, Notch2, and c-Myc oncoproteins, was detected. However, only c-Myc was consistently confirmed as a FBXW7 target in human CCA cell lines. Interestingly, selected ablation of c-Myc completely impaired iCCA formation in AKT/Fbxw7ΔF mice, whereas deletion of either Yap or Notch2 delayed cholangiocarcinogenesis in the same model. Furthermore, in human iCCA specimens, a strong, inverse correlation between the expression levels of FBXW7 and c-Myc was observed. Conclusions: Downregulation of FBXW7 is almost ubiquitous in human iCCA and cooperates with AKT to induce cholangiocarcinogenesis in mice. This pre-clinical mouse model could be used to test novel therapeutics targeting c-Myc, Notch2, and/or Yap.

Genomic analysis of hepatocellular carcinoma (HCC) with active hepatitis B virus (HBV) replication

e15593

Background: HBV replication contributes to HCC initiation and is associated with worse patient outcomes. Prior tumor genomic studies of HBV-positive and -negative (HBV+/-) HCC have used detection of HBV surface antigen (HBsAg) in serum to annotate HBV status. However, a substantial proportion of HBsAg+ patients lack HBV replication in tumor, suggesting a potentially distinct patient subset. In this study, we determined HBV status by measuring tumor HBV RNA, a proxy for active replication. We then investigated HBV RNA+/- association with somatic mutations, gene sets, homologous recombination deficiency (HRD) and tumor mutation burden (TMB). Methods: RNA-Seq data for 371 HCC tumors were obtained from TCGA. Tumors were classified as HBV RNA+ if they harbored more than 1 HBV RNA read per million human reads, as measured using GATK PathSeq software. Associations between HBV RNA status and somatic mutations, gene sets, HRD and TMB were investigated. HRD score was calculated as the sum of 3 independent HRD measures (large scale state transitions, loss of heterozygosity and telomeric allelic imbalance). Results: HBV RNA+ status was associated with a higher rate of nonsynonymous somatic mutations in multiple genes, including the tumor suppressors TP53, CDKN2A, CHD5 and TET1, as well as AXIN2 and the proto-oncogene BCL11A ( p < 0.05 for all), while HBV RNA- status was associated with a higher rate of nonsynonymous mutations in the chromatin modifier BAP1 ( p = 0.03). In gene set enrichment analysis of normalized RNA-Seq expression data, HBV RNA+ status was associated with increased transcription of DNA repair genes, as well as genes upregulated by mTORC1 and MYC (FDR < 0.03 for all). HBV RNA status was also associated with HRD score (22.19 for HBV RNA+ vs. 15.97 for HBV RNA-, p = 1e-6), but not with TMB. A substantial subset of HBV RNA+ patients (33/100) were not annotated as HBV+ in the TCGA clinical database. Conclusions: HBV status based on tumor HBV RNA detection identifies a genetically distinct subset within all HBV-infected HCC patients that is associated with nonsynonymous somatic mutations in several genes and differential transcription of gene sets, some of which have not been previously reported, as well as with HRD score. These findings suggest potential for differential responsiveness to targeted therapies.

Phase II multicenter pilot study of safety, efficacy, and immune cell profiling in advanced hepatocellular carcinoma (HCC) on combination of sorafenib (SOR) plus nivolumab (NIVO)

TPS464

Background: The antiangiogenic tyrosine kinase inhibitor (TKI) SOR prolongs survival in advanced HCC, but responses occur in fewer than 5% of patients (pts) and median progression-free survival (PFS) is less than 6 months. Immune checkpoint inhibition (CPI) with the PD-1 inhibitor, NIVO, achieved an overall response rate (ORR) of approximately 20% in sorafenib-naïve pts enrolled on CheckMate 040 trial though most pts had progression. In preclinical studies, TKI can inhibit regulatory T cells and myeloid derived suppressor cells, immune cell subsets which may contribute to CPI resistance. CD8+ T cells in sorafenib-resistant tumors are characterized by PD-1 expression, providing rationale for a combined approach. The combination of TKI or the anti-angiogenic bevacizumab with CPI improves anti-tumor activity in HCC mouse models and in preliminary clinical studies. This study will examine the safety, maximum tolerated dose (MTD), and ORR of the combination of SOR plus NIVO in advanced HCC pts, along with correlative analyses of tumor and circulating immune cells. Methods: Eligible pts must have Child-Pugh A liver function and advanced HCC, without prior systemic therapy and measurable by RECIST 1.1. In Part 1 (3+3 dose escalation), SOR dose will be 400 mg QD or BID plus NIVO 240 mg IV Q2 weeks. In Part 2, Arm 1, pts will start NIVO Cycle 1, Day 1 (C1D1), with addition of SOR at MTD on C1D15; in Part 2, Arm 2, SOR is given at MTD on C1D1 with addition of NIVO on C1D15. Primary endpoints are MTD of SOR (Part 1) and ORR by RECIST 1.1 with H0 7.5% vs. H1 25% (Part 2). For expected sample size of 24 evaluable pts in Part 2, the power is 83% with 1-sided alpha 5% to determine ORR >25% by Chi-square tests. Secondary endpoints are safety, duration of response, PFS, and overall survival. Exploratory endpoints include peripheral and tumor immune cell profiling, PD-L1 expression, and alpha-fetoprotein (AFP) response. An interim safety analysis will be performed after 50% enrollment in Part 2. Optional paired biopsies in Part 2 will allow for investigation of the tumor microenvironment on SOR, NIVO, and combination. Clinical trial information: NCT03439891.

Changes in alpha-fetoprotein (AFP) and systemic therapy outcomes in advanced hepatocellular carcinoma (HCC): A multicenter retrospective analysis

346

Background: AFP is elevated in 70% of HCC and is associated with poor prognosis. The role of AFP as a biomarker of response to systemic treatments has not been established, though small, retrospective studies show association between AFP decline and survival on sorafenib. The relationship between AFP changes and response to immune checkpoint inhibitors (CPI) has not been reported. This study examines AFP changes on treatment for association with outcomes on first-line (1L) SOR and any subsequent CPI in a contemporary, multicenter U.S. population. Methods: Design: Multicenter retrospective case series. Key eligibility: Received 1L SOR or SOR-based combination for advanced HCC; ≥ 1 post-treatment AFP value available; enrolled on IRB-approved registry. Objectives: associate AFP changes within 3 months of start of treatment with overall survival (OS) and time on treatment (TOT) on 1L SOR and any subsequent CPI; associate baseline AFP with OS and TOT for SOR and CPI; relate baseline AFP and changes on treatment to clinical covariates. Results: 152 patients were identified from two centers. Baseline characteristics: M/F 132/20; HBV/HCV/nonviral 40/71/41; Child Pugh A/B 128/23; BCLC A/B/C: 4/15/133. Baseline AFP < 20/ ≥ 400: 43/59. 43 received CPI after SOR. See Table. Baseline AFP was not related to TOT or OS for SOR or CPI. Multivariable analyses for AFP with clinical covariates will be presented. Conclusions: This series is the largest multicenter analysis of AFP response to systemic therapy with SOR and CPI. AFP decrease and increase within the first 3 months of treatment with SOR and CPI were inversely and significantly associated with median OS. AFP warrants further study in randomized cohorts as a biomarker of response to systemic therapy in HCC, now with multiple treatment options available at progression.[Table: see text]

Phase II trial of pembrolizumab (PEM) plus granulocyte macrophage colony stimulating factor (GM-CSF) in advanced biliary cancers (ABC)

386

Background: The efficacy of immune checkpoint inhibition (CPI) has not been established in ABC. GM-CSF modulates immune effector cells and has demonstrated safety and improved survival (OS) in combination with ipilimumab in melanoma. This phase 2 trial aims to evaluate the efficacy and safety of PEM in combination with GM-CSF in ABC. Methods: Design: Simon’s 2-stage. Key eligibility: ABC with progression/intolerance on ≥ 1 standard therapy, no prior CPI, bilirubin ≤1.5xULN. Treatment: PEM 200 mg IV Q21 days plus 2 cycles of GM-CSF 250 µg SC D1-14 Q21 days in cycles 2 and 3 (Stage 1 Safety Cohort) or in cycles 1 and 2 (Stage 2). Endpoints: 1◦: Progression-free survival at 6 months (PFS6) with H0 25% vs. H1 50%. Key 2◦: Safety, overall response rate (ORR) and duration (DOR), OS, PD-L1 expression. Exploratory: PBMC and tumor immune cell profiles, tumor genotype, microsatellite (in)stability (MSI or MSS). Results: Accrual has completed with 27 patients (pts) enrolled 5/2016-6/2017: F/M 13/14; median age 61 (range 37-77); intrahepatic 19 (70%), extrahepatic 7 (26%), mixed 1 (4%) cholangiocarcinoma; stage IVA/B 85%, II/III 15%; median prior therapies 2 (range 1-6). Adverse events (AE): Related grade(Gr) ≥3 AE occurred in 4/27 (15%) pts including immune-related (ir)AE of Gr4 diabetes mellitus and Gr3 thrombocytopenia in 1 pt each. Gr≤2 irAE in ≥5% were: arthralgia (33%), dry eye/mouth (15%), hyperthyroid/thyroiditis (15%), hypothyroid (15%), neuropathy (11%), rash (11%), and adrenal insufficiency (7%). Steroids were required in 3/27 (11%) pts. Disposition: 19 pts removed for PD, 1 for Gr2 irAE; 7 pts remain active on treatment. Median time on treatment: 6 cycles (range 2-22+). Best response by RECIST 1.1: Partial response (PR) in 5/24 (21%) evaluable pts (1 MSI, 4 MSS); minor regression and ≥50% CA 19-9 decline in 2 additional MSS pts for 11+ and 16+ months. PBMC analyses show changes in expression of activating and inhibitory markers including PD-1 on various immune cell populations. Conclusions: PEM plus induction GM-CSF is safe and tolerable in ABC. Durable radiographic and tumor marker responses including MSS pts warrant further study. PFS6, OS, and correlative analyses are ongoing. Clinical trial information: NCT02703714.

Nivolumab in advanced hepatocellular carcinoma (HCC) and Child Pugh B (CPB) cirrhosis: Safety and clinical outcomes in a retrospective case series

496

Background: HCC patients (pts) with Child Pugh B (CPB) cirrhosis have poor prognosis and limited treatment (Tx) options. Nivolumab demonstrated durable responses and acceptable safety in Child Pugh A (CPA) HCC in the CheckMate-040 trial with rates of hepatotoxicity similar to non-HCC populations. The safety and efficacy of nivolumab has not been established in pts with CPB cirrhosis. Methods: Design: Retrospective case series with IRB approval. Key eligibility: HCC with CPB cirrhosis; treated with nivolumab as standard Tx; enrolled in the UCSF Hepatobiliary Tissue Bank and Registry. Study endpoints: Safety during nivolumab Tx including all-cause grade(Gr) ≥ 3 adverse events (AE), serious AE (SAE), any grade immune-related (ir)AE, and systemic steroid (SS) requirement; clinical outcomes including time on Tx (TOT) with nivolumab and overall survival (OS). Results: Thirteen pts were included: male 77%; Asian 38%, white 54%; median age 66 (range: 26-86); HCV Ab+ 31%, HBsAg+ 23%; BCLC B/C 31%/69%; median Child-Pugh score 8; median prior systemic Tx 1 (range: 0-6); prior sorafenib 69%, median duration on prior sorafenib 137 days (range 10-341). The Table depicts safety outcomes on nivolumab. Median TOT on nivolumab: 44 days (95% CI: 32, 98) (range: 17-811+). Median OS from start of nivolumab: 119 days (95% CI: 40, 247) (range: 40-811+). Best response of at least stable disease occurred in 3/13 (23%) of patients, including prolonged stable disease (SD) for 6+ months and complete response (CR) for 24+ months on nivolumab (1 pt each). Conclusions: CPB HCC pts treated with nivolumab experienced high rates of all-cause Gr ≥ 3 AE and SAE and short OS, similar to prior studies in CPB HCC. Rates of irAE attributed to nivolumab were similar to rates reported in CheckMate-040 CPA population, without unexpected AE. A subset of pts experienced prolonged stable disease and CR. Nivolumab warrants further study in CPB HCC.[Table: see text]

Detection of circulating tumor cells (CTC) using a non-EpCAM-based, high-definition, single-cell assay in advanced hepatocellular carcinoma (HCC) for patients enrolled on phase I and II trials of sorafenib plus temsirolimus

311

Background: Noninvasive biomarkers are needed for diagnosis, prognosis, and molecular profiling of HCC due to scarcity of tumor tissue and heterogeneous tumor biology. CTC are detectable in metastatic HCC using methods which enrich for expression of the cell adhesion molecule, EpCAM. Because a subset of HCC does not express EpCAM, however, non-EpCAM enrichment methods are needed for CTC studies in HCC. Methods: This CTC cohort was derived from patients enrolled on multicenter phase 1 and 2 trials of the combination of sorafenib plus temsirolimus in advanced HCC (NCT01008917, NCT01687673) with approval and funding from the National Comprehensive Cancer Network (NCCN) Oncology Research Program. Eligibility required histologic diagnosis of incurable HCC with no prior systemic therapy. All patients in the cohort were treated at the recommended phase 2 dose of sorafenib 200 mg PO BID and temsirolimus 10 mg IV weekly. Whole blood samples were collected at baseline and on treatment. CTC were enumerated and analyzed cytomorphologically using a high-definition, single cell assay without EpCAM enrichment and blinded to clinical outcomes. Results: The CTC cohort was comprised of 36 patients (phase 1 n = 9, phase 2 n = 27). Characteristics: male 89%; white 64%, Asian/PI 28%, black 6%; HBsAg+ 31%, HCV+ 44%; Child Pugh A 92%, B7 8%; BCLC C 83%; tumor vascular invasion 47%; median AFP 74 ng/mL. Median OS from start of treatment was 392 days (95% CI: 214, 569). CTC ≥ 1/mL were detectable at baseline in 23/36 (64%) overall (95% CI: 47%, 80%), with similar findings in the phase 1 (56%) and phase 2 (67%) subsets. There was no significant relationship between baseline CTC values ≥ 1, 2, or 5/mL and overall survival (OS) on univariate analysis. Analyses of CTC relationship to clinical characteristics and time to progression, changes on treatment, and multivariable analysis for relationship to OS will be presented. Conclusions: CTC were detected in over 60% of patients in this advanced HCC clinical trial cohort using a non-EpCAM, high-definition single cell assay, suggesting future potential for noninvasive molecular profiling of HCC.

Next-generation sequencing (NGS) in an advanced hepatocellular carcinoma (HCC) cohort: Analyses of TP53 and CTNNB1

286

Background: Mutations in TP53 and CTNNB1 are common in early stage HCC resection samples. The frequency and prognostic impact of these mutations in advanced HCC is not known. We conducted this retrospective analysis using a large NGS panel to explore for association between tumor genetics, clinicopathologic features, and prognosis in an advanced HCC cohort. Methods: Eligible cases had diagnosis of unresectable HCC or mixed HCC-cholangiocarcinoma and were enrolled on NCT01008917 or NCT01687673 clinical trials of sorafenib plus temsirolimus with informed consent for specimen banking for future research including genetic testing. Paired tumor and germline (blood) DNA samples were sequenced using a capture-based NGS cancer panel to allow for determination of somatic variants. Analysis was based on the human reference sequence UCSC build hg19. Variants were called using GATK Unified Genotyper software. Somatic, non-synonymous, and exonic calls were curated using COSMIC, cBioPortal, and Pubmed. Results: Cases with HCC (n = 21) and mixed HCC-cholangiocarcinoma (n = 2) comprised the cohort (N = 23). Male/female: 83%/17%. Race: White 56%, Asian 39%. BCLC stage: B 35%, C 65%. Etiology: HBsAg+ 26%, HCV+ 39%. Immune infiltrates ( ≥ 1 on scale 0-3) were present in 7/12 (58%) evaluable tumor samples. TP53 mutations were present in 14/23 (61%, 95% CI: 38.5, 80.0). CTNNB1 mutations were present in 7/23 (30%, 95% CI: 13.2, 52.9). There was no significant difference between HBsAg+ and HCV+. Both TP53 and CTNNB1 mutation were present in 4/23 (17%). CTNNB1 mutation was present in 2/7 (29%) cases with immune infiltrate score ≥ 1, and 1/5 (20%) with score < 1 (not significant). Other mutations and variants will be reported. Conclusions: NGS in this advanced HCC cohort suggests a higher incidence of TP53 and coexisting TP53 plus CTNNB1 mutations than has been reported in early stage HCC which requires confirmation in a larger cohort. There was no clear relationship between these mutations, HCC etiology, or tumor immune infiltrates though interpretation is limited by small sample sizes. Analyses are ongoing to explore for association between TP53 and CTNNB1 mutations and prognosis in this advanced HCC cohort.

Phase II trial of temsirolimus (TEM) plus sorafenib (SOR) in hepatocellular carcinoma (HCC)

TPS501

Background: The multikinase inhibitor SOR prolongs survival in patients with HCC not amenable to curative therapies. In HCC preclinical models, the combination of SOR with an inhibitor of the mammalian target of rapamycin (mTOR) pathway is synergistic, though single-agent mTOR inhibition did not improve survival in HCC patients after failure of SOR in a phase III trial. We previously completed a phase I study of the mTOR inhibitor TEM combined with SOR in 25 HCC patients which identified the maximum tolerated dose as TEM 10 mg IV weekly and SOR 200 mg PO BID. This two-center, phase II study was developed to examine the efficacy of the combination and to explore candidate biomarkers. The study was approved and funded by the National Comprehensive Cancer Network (NCCN) Oncology Research Program from general research support, with activation October 2012. Methods: The study is registered on ClinicalTrials.gov (NCT01687673). Design: Single-arm, one stage phase II trial. Primary endpoint: Time to progression (TTP) by RECIST 1.1. Other endpoints: Progression-free survival, response rate, overall survival, proportion with alpha fetoprotein decline ≥ 50%, toxicity, hepatitis B virus reactivation rate, and exploratory biomarkers including mTOR pathway protein expression in tumor, circulating tumor cells, and blood and tumor micro-RNA profiles. Sample size: 25 evaluable patients are required to detect a difference between the null hypothesis of median TTP < 3 months versus alternate hypothesis of median TTP ≥ 6 months (a clinically-meaningful outcome in advanced HCC), with 1-sided significance level of 10% and power 88% under the exact test. Main eligibility criteria: HCC not amenable to curative therapies, histologically-confirmed, ≥ 1 untreated, radiographically-measurable site of disease. No prior systemic therapy. ECOG ≤ 1. Child-Pugh score ≤ 7 with bilirubin ≤ 2 mg/dL. Treatment and procedures: TEM 10 mg IVweekly plus SOR 200 mg PO BID in 28-day cycles, with collection of archival tumor samples and blood samples at baseline, on treatment, and at progression. Accrual:Sixteen of 25 planned evaluable patients have enrolled. An interim analysis for safety after 30% enrollment met pre-specified target to continue. Clinical trial information: NCT01687673.

Ror2, a developmentally regulated kinase, promotes tumor growth potential in renal cell carcinoma

Inappropriate kinase expression and subsequent promiscuous activity defines the transformation of many solid tumors including renal cell carcinoma (RCC). Thus, the expression of novel tumor-associated kinases has the potential to dramatically shape tumor cell behavior. Further, identifying tumor-associated kinases can lend insight into patterns of tumor growth and characteristics. Here, we report the identification of the RTK-like orphan receptor 2 (Ror2), a new tumor-associated kinase in RCC cell lines and primary tumors. Ror2 is an orphan receptor tyrosine kinase with physiological expression normally seen in the embryonic kidney. However, in RCC, Ror2 expression correlated with expression of genes involved at the extracellular matrix, including Twist and matrix metalloprotease-2 (MMP2). Expression of MMP2 in RCC cells was suppressed by Ror2 knockdown, placing Ror2 as a mediator of MMP2 regulation in RCC and a potential regulator of extracellular matrix remodeling. The suppression of Ror2 not only inhibited cell migration, but also inhibited anchorage-independent growth in soft agar and growth in an orthotopic xenograft model. These findings suggest a novel pathway of tumor-promoting activity by Ror2 within a subset of renal carcinomas, with significant implications for unraveling the tumorigenesis of RCC.

Universal tumor antigens as targets for immunotherapy

BACKGROUND

Clinically successful Ag-specific cancer immunotherapy depends on the identification of tumor-rejection Ags. Historically, tumor Ags have been identified by analyzing cancer patients' own T-cell or Ab responses.

METHODS

The unveiling of the human genome and optimized immunological analytical tools, particularly 'reverse immunology', have made it possible to screen any given protein for immunogenic epitopes. These advances enable the immunological characterization of universal tumor-associated gene products that mediate critical functions for tumor growth and development.

RESULTS

Four examples of candidate universal tumor Ags reviewed here include the telomerase reverse transcriptase (hTERT), the inhibitor of apoptosis survivin, the p53-interacting protein MDM2, and the cytochrome P450 isoform 1B1--each at various levels of preclinical and clinical development.

DISCUSSION

The cardinal feature of universal TAA is that they are expressed in (nearly) all tumors and in no normal tissues. They are directly involved in the malignant phenotype of the tumor. Certain peptides derived from such Ags are expressed on the tumor-cell surface, as evidenced by Ag-specific, MHC-restricted T-cell anti-tumor reactivity in vitro. It is hoped that these features imply a pre-existing, high-affinity T-cell pool that can be activated in vivo in patients, without immunoselection of variant tumor cells no longer expressing the Ag of choice.

Antigens recognized by autologous antibody in patients with renal-cell carcinoma

The screening of cDNA expression libraries derived from human tumors with autologous antibody (SEREX) is a powerful method for defining the structure of tumor antigens recognized by the humoral immune system. Sixty-five distinct antigens (NY-REN-1 to NY-REN-65) reactive with autologous IgG were identified by SEREX analysis of 4 renal cancer patients and were characterized in terms of cDNA sequence, mRNA expression pattern, and reactivity with allogeneic sera. REN-9, -10, -19, and -26 have a known association with human cancer. REN-9 (LUCA-15) and REN-10 (gene 21) map to the small cell lung cancer tumor suppressor gene locus on chromosome 3p21.3. REN-19 is equivalent to LKB1/STK11, a gene that is defective in Peutz-Jeghers syndrome and cancer. REN-26 is encoded by the bcr gene involved in the [t(9:22)] bcr/abl translocation. Genes encoding 3 of the antigens in the series showed differential mRNA expression; REN-3 displays a pattern of tissue-specific isoforms, and REN-21 and REN-43 are expressed at a high level in testis in comparison to 15 other normal tissues. The other 62 antigens were broadly expressed in normal tissues. With regard to immunogenicity, 20 of the 65 antigens reacted only with autologous sera. Thirty-three antigens reacted with sera from normal donors, indicating that their immunogenicity is not restricted to cancer. The remaining 12 antigens reacted with sera from 5-25% of the cancer patients but not with sera from normal donors. Seventy percent of the renal cancer patients had antibodies directed against one or more of these 12 antigens. Our results demonstrate the potential of the SEREX approach for the analysis of the humoral immune response against human cancer.

Isoforms of the human PDZ-73 protein exhibit differential tissue expression

Patients with renal and colon cancer frequently develop IgG autoantibodies toward the NY-CO-38/PDZ-73 antigen, a protein of 652 amino acids (73 kDa) which contains three copies of the PDZ protein-protein interaction domain. The gene encoding PDZ-73 mapped to chromosome 11p15.4-p15.1. Additional tissue-specific isoforms were identified: PDZ-45, which lacks the third PDZ domain and the putative PEST protein degradation motif, is expressed in kidney, colon, small intestine, brain and testis; PDZ-54 and PDZ-59, which also lack the third PDZ domains, have unique carboxyl terminal amino acids and are expressed in brain, kidney, bladder, colon cancer and renal cancer; and a putative PDZ-37 isoform, containing only the third PDZ domain, that is expressed in the central nervous system. Immunohistochemical staining with anti-PDZ 73 monoclonal antibodies showed strong cytoplasmic reactivity in epithelial cells of the small intestine, colon and kidney tubules, with a prominent apical staining pattern in cells of the small intestine. The reactivity pattern of the antibodies with various tissues correlated with the mRNA expression pattern of the PDZ-45 isoform. The existence of multiple PDZ-73 isoforms with variations in tissue distribution, PDZ domains, protein degradation sequences and carboxyl terminal structure indicate that these isoforms have distinct tissue-specific functions.

Characterization of human colon cancer antigens recognized by autologous antibodies

The screening of cDNA expression libraries derived from human tumors with autologous antibody (SEREX) has proven to be a powerful method for defining the structure of tumor antigens recognized by the humoral immune system. In the present study, 48 distinct antigens (NY-CO-1-NY-CO-48) reactive with autologous IgG were identified by SEREX analysis in 4 patients with colon cancer. Sequencing analysis showed that 17 of the cDNA clones were previously uncharacterized molecules and 31 represented known gene products. The individual cDNA clones were analyzed in the following manner: a search for mutations or other structural changes; an analysis of mRNA expression in a panel of normal tissues; and a frequency analysis of the antibody response to the expressed product in the sera of colon cancer patients and normal individuals. The initial analysis showed NY-CO-13 to be a mutated version of the p53 tumor suppressor gene. Three of the 48 antigens showed a differential pattern of mRNA expression, with NY-CO-27 (galectin-4) expressed primarily in gastrointestinal tract, and NY-CO-37 and -38 showing a pattern of tissue-specific isoforms. With regard to immunogenicity, 20 of the 48 antigens were detected by allogeneic sera; 14 of these were reactive with sera from both normal donors and cancer patients, and 6 other clones (NY-CO-8, -9, -13, -16, -20 and -38) reacted exclusively with sera from colon cancer patients (ranging from 14% to 27%). Our results on colon cancer illustrate both the complexity and the potential of the SEREX approach for analysis of the humoral immune response against human cancer.

Characterization of human colon cancer antigens recognized by autologous antibodies

The screening of cDNA expression libraries derived from human tumors with autologous antibody (SEREX) has proven to be a powerful method for defining the structure of tumor antigens recognized by the humoral immune system. In the present study, 48 distinct antigens (NY-CO-1-NY-CO-48) reactive with autologous IgG were identified by SEREX analysis in 4 patients with colon cancer. Sequencing analysis showed that 17 of the cDNA clones were previously uncharacterized molecules and 31 represented known gene products. The individual cDNA clones were analyzed in the following manner: a search for mutations or other structural changes; an analysis of mRNA expression in a panel of normal tissues; and a frequency analysis of the antibody response to the expressed product in the sera of colon cancer patients and normal individuals. The initial analysis showed NY-CO-13 to be a mutated version of the p53 tumor suppressor gene. Three of the 48 antigens showed a differential pattern of mRNA expression, with NY-CO-27 (galectin-4) expressed primarily in gastrointestinal tract, and NY-CO-37 and -38 showing a pattern of tissue-specific isoforms. With regard to immunogenicity, 20 of the 48 antigens were detected by allogeneic sera; 14 of these were reactive with sera from both normal donors and cancer patients, and 6 other clones (NY-CO-8, -9, -13, -16, -20 and -38) reacted exclusively with sera from colon cancer patients (ranging from 14% to 27%). Our results on colon cancer illustrate both the complexity and the potential of the SEREX approach for analysis of the humoral immune response against human cancer.

Mathematical exploration of pulsatility in cultured gonadotropin-releasing hormone neurons

Pulsatile gonadotropin-releasing hormone (GnRH) release has been demonstrated in cultures of an immortalized line of GnRH expressing neurons (GT1 cells) in experiments by four different research groups. Pulsatile release is known to play a crucial role in GnRH-mediated signaling in vivo, and thus deserves theoretical and quantitative consideration, especially as GT1 cells are presumably genetically homogeneous. Here we have modeled idealized GT1 cells with a differential equation/logic based modeling program, Stella II. We have created a network of 'neurons', with randomized (within the same preset limits for each neuron) thresholds, number and weight of connections to other neurons, and build-up of signal; as well as continuous decay of stored signal. Surprisingly, we found that with this minimal set of assumptions, without any sort of predefined pacemaking cells, it is possible to create pulsatility similar to that observed in the laboratory. A variety of different parameter sets was found to produce these pulses. Network behaviors similar to those of GT1 cells depended on the degree of interconnection between neurons and their functioning within a critical range of network excitability. These findings allow for a clearer consideration of the critical elements of such networks as well as experimental predictions regarding the production of pulsatile behavior.

Reproductive functions illustrating direct and indirect effects of genes on behavior

Effects of gene products on reproductive behavior which are relatively direct include those of the estrogen receptor and progesterone receptor. For example, work with estrogen receptor-deficient (ERKO) female mice has extended previous evidence contributing to the neurochemical analysis of lordosis behavior. On the other hand, sex differences in behavior present a classic example of indirect effects of genes on behavior. Work with ERKO male mice shows the necessity of ER gene expression for normal masculinization of the brain. In particular, behavioral assay results distinguish apparent motivational performance of ERKO males from male mating reflexes: the former is similar to that of wild-type males in important respects, while the latter are deficient in ERKO males. The present paper first reviews a small number of clear genetic contributions to reproductive behaviors, and then reports one experiment pertinent to the interpretation of the behavioral status of ERKO male mice.