Phase I Study of the CD47 Blocker TTI-621 in Patients with Relapsed or Refractory Hematologic Malignancies.

PURPOSE: TTI-621 (SIRPα-IgG1 Fc) is a novel checkpoint inhibitor that activates antitumor activity by blocking the CD47 "don't eat me" signal. This first-in-human phase I study (NCT02663518) evaluated the safety and activity of TTI-621 in relapsed/refractory (R/R) hematologic malignancies. PATIENTS AND METHODS: Patients with R/R lymphoma received escalating weekly intravenous TTI-621 to determine the maximum tolerated dose (MTD). During expansion, patients with various malignancies received weekly single-agent TTI-621 at the MTD; TTI-621 was combined with rituximab in patients with B-cell non-Hodgkin lymphoma (B-NHL) or with nivolumab in patients with Hodgkin lymphoma. The primary endpoint was the incidence/severity of adverse events (AEs). Secondary endpoint included overall response rate (ORR). RESULTS: Overall, 164 patients received TTI-621: 18 in escalation and 146 in expansion (rituximab combination, n = 35 and nivolumab combination, n = 4). On the basis of transient grade 4 thrombocytopenia, the MTD was determined as 0.2 mg/kg; 0.1 mg/kg was evaluated in combination cohorts. AEs included infusion-related reactions, thrombocytopenia, chills, and fatigue. Thrombocytopenia (20%, grade ≥3) was reversible between doses and not associated with bleeding. Transient thrombocytopenia that determined the initial MTD may not have been dose limiting. The ORR for all patients was 13%. The ORR was 29% (2/7) for diffuse large B-cell lymphoma (DLBCL) and 25% (8/32) for T-cell NHL (T-NHL) with TTI-621 monotherapy and was 21% (5/24) for DLBCL with TTI-621 plus rituximab. Further dose optimization is ongoing. CONCLUSIONS: TTI-621 was well-tolerated and demonstrated activity as monotherapy in patients with R/R B-NHL and T-NHL and combined with rituximab in patients with R/R B-NHL.

Integrative Transcriptome Analyses of the Human Fallopian Tube: Fimbria and Ampulla-Site of Origin of Serous Carcinoma of the Ovary.

Epithelial ovarian cancer represents a group of heterogeneous diseases with high grade serous cancer (HGSC) representing the most common histotype. Molecular profiles of precancerous lesions found in the fallopian tube have implicated this tissue as the presumptive site of origin of HGSC. Precancerous lesions are primarily found in the distal fallopian tube (fimbria), near the ovary relative to the proximal tissue (ampulla), nearer to the uterus. The proximity of the fimbria to the ovary and the link between ovulation, through follicular fluid release, and ovarian cancer risk led us to examine transcriptional responses of fallopian tube epithelia (FTE) at the different anatomical sites of the human fallopian tube. Gene expression profiles of matched FTE from the fimbria and from premenopausal women resulted in differentially expressed genes (DEGs): CYYR1, SALL1, FOXP2, TAAR1, AKR1C2/C3/C4, NMBR, ME1 and GSTA2. These genes are part of the antioxidant, stem and inflammation pathways. Comparisons between the luteal phase (post-ovulation) to the follicular phase (pre-ovulation) demonstrated greater differences in DEGs than a comparison between fimbria and fallopian tube anatomical differences alone. This data suggests that cyclical transcriptional changes experienced in pre-menopause are inherent physiological triggers that expose the FTE in the fimbria to cytotoxic stressors. These cyclical exposures induce transcriptional changes reflective of genotoxic and cytotoxic damage to the FTE in the fimbria which are closely related to transcriptional and genomic alterations observed in ovarian cancer.

CCAAT/enhancer binding protein delta (C/EBPδ) demonstrates a dichotomous role in tumour initiation and promotion of epithelial carcinoma.

BACKGROUND: CCAAT/enhancer binding protein delta (C/EBPδ,CEBPD), a gene part of the highly conserved basic-leucine zipper (b-ZIP) domain of transcriptional factors, is downregulated in 65% of high grade serous carcinomas of the ovary (HGSC). Overexpression of C/EBPδ in different tumours, such as glioblastoma and breast cancer either promotes tumour progression or inhibits growth and has low expression in normal tissue until activated by cytotoxic stressors. METHODS: Higher overall expression of C/EBPδ in the luteal phase of the menstrual cycle prompted us to investigate the role of C/EBPδ in carcinogenesis. In vitro experiments were conducted in fallopian tube cell samples and cancer cell lines to investigate the role of C/EBPδ in proliferation, migration, and the epithelial to mesenchymal transition. FINDINGS: Expression of C/EBPδ induced premature cellular arrest and decreased soft agar colony formation. Loss of C/EBPδ in epithelial cancer cell lines did not have significant effects on proliferation, yet overexpression demonstrated downregulation of growth, similar to normal fallopian tube cells. C/EBPδ promoted a partial mesenchymal to epithelial (MET) phenotype by upregulating E-cadherin and downregulating Vimentin and N-cadherin in FTE cells and increased migratory activity, which suggests a regulatory role in the epithelial-mesenchymal plasticity of these cells. INTERPRETATION: Our findings suggest that C/EBPδ regulates the phenotype of normal fallopian tube cells by acting on downstream regulatory factors that are implicated in the development of ovarian serous carcinogenesis. FUND: This study was funded by the CDMRP Ovarian Cancer program (W81WH-0701-0371, W81XWH-18-1-0072), the Princess Margaret Cancer Centre Foundation, Foundation for Women's Cancer - The Belinda-Sue/Mary-Jane Walker Fund, Colleen's Dream Foundation and Sylvester Comprehensive Cancer Center.

A distinct innate lymphoid cell population regulates tumor-associated T cells.

Antitumor T cells are subject to multiple mechanisms of negative regulation. Recent findings that innate lymphoid cells (ILCs) regulate adaptive T cell responses led us to examine the regulatory potential of ILCs in the context of cancer. We identified a unique ILC population that inhibits tumor-infiltrating lymphocytes (TILs) from high-grade serous tumors, defined their suppressive capacity in vitro, and performed a comprehensive analysis of their phenotype. Notably, the presence of this CD56+CD3- population in TIL cultures was associated with reduced T cell numbers, and further functional studies demonstrated that this population suppressed TIL expansion and altered TIL cytokine production. Transcriptome analysis and phenotypic characterization determined that regulatory CD56+CD3- cells exhibit low cytotoxic activity, produce IL-22, and have an expression profile that overlaps with those of natural killer (NK) cells and other ILCs. NKp46 was highly expressed by these cells, and addition of anti-NKp46 antibodies to TIL cultures abrogated the ability of these regulatory ILCs to suppress T cell expansion. Notably, the presence of these regulatory ILCs in TIL cultures corresponded with a striking reduction in the time to disease recurrence. These studies demonstrate that a previously uncharacterized ILC population regulates the activity and expansion of tumor-associated T cells.

Retinoblastoma pathway deregulatory mechanisms determine clinical outcome in high-grade serous ovarian carcinoma.

Alterations in the retinoblastoma pathway are frequent in ovarian/tubal high-grade serous cancers, but the mechanism of deregulation and the impact on patient outcome are poorly understood. A cohort of 334 high-grade serous carcinomas was studied by immunohistochemical analysis of RB1, p16, cyclin D1, cyclin E1, and Ki67. Additional detailed analyses including RB1 allelic deletion (n=42), mutation (n=75), methylation (n=31), and SNP array analyses (n=75) were performed on cases with clinical parameters, including age, debulking status, treatment, and clinical outcome. p16/RB1 expression results yielded three distinct clinically relevant subgroups upon multivariable analysis controlling for stage, debulking status, and treatment types: p16 homogeneous/RB1+ with the shortest progression-free survival (median 15 months (95% CI: 13-18); P=0.016) compared with the p16 heterogeneous/RB1+ subgroup (median 22 months (95% CI: 16-32)) and the p16 homogeneous/RB1- subgroup (median 20 months (95% CI: 15-24)). Patients in the p16 homo/RB1- subgroup showed a significant increase in overall survival (>60 months; P=0.013), which suggests an increase in sensitivity to cytotoxic agents. Analyses of Rb pathway mechanistic differences among these groups revealed frequent RB1 genomic alterations such as RB1 allelic loss and/or large spanning deletions (83%) in the p16 homo/RB1- subgroups, also indicating that RB1 deletions are frequent in high-grade serous carcinoma. CCNE1 gene gains/amplifications were frequent in the p16 homogeneous/RB1+ subgroup (68%) and cyclin D1 protein overexpression was predominantly characteristic of the p16 heterogeneous/RB1+ subgroup. These subcategories occur early in tumor progression and are seen with similar frequency in the cancer precursor lesion, serous tubal intra-epithelial carcinoma. Overall, this study uniquely identifies multiple non-synonymous mechanisms of retinoblastoma pathway deregulation that correlate with significantly different clinical outcomes. Furthermore, deregulations identified in precursor lesions suggest a key role of this pathway in serous tumor development. Recognition of these categories may identify patients with increased sensitivity to chemotherapy and new opportunities for novel therapeutics.

Proliferation in the normal FTE is a hallmark of the follicular phase, not BRCA mutation status.

PURPOSE: Women who have inherited germline mutations of BRCA1/BRCA2 are at increased risk of developing high-grade serous carcinoma, and many of these cancers arise in the distal fimbriated end of the fallopian tube. We have previously shown that the fallopian tube epithelia of BRCA1 mutation carriers (FTE-BRCA) have altered signaling pathways compared to nonmutation carriers. In this study, we sought to determine whether these differences result in a proliferative advantage to the epithelia in this high-risk patient population and to investigate whether the postovulation environment of the FTE-BRCA compared to FTE from nonmutation carriers experiences a differential abundance of immune cells. METHOD: Immunohistochemistry for Ki67, CD3, CD8, CD20, and CD68 was performed on histologically normal tubal epithelium (ampulla, n = 83), fimbria (n = 18) with known ovarian cycle status and germline mutation status and for Ki67 on fimbrial epithelium from women (n = 144) with and without BRCA1 or BRCA2 mutations who underwent risk-reducing salpingo-oophorectomy (RRSO). Serous tubal intraepithelial carcinomas (STIC) with concomitant cancer (n = 15) were also analyzed for presence of immune infiltrates. All slides were digitized and analyzed using automated image analysis software. RESULTS: There was no significant difference in the proliferative index in histologically normal FTE between BRCA1/BRCA2 and non-BRCA, in 144 fimbriae and 83 ampullae. The FTE-BRCA1 epithelia did not exhibit a differential presence of lymphocytes or macrophages, however more macrophages were present in the luteal phase compared to the follicular phase epithelia. In STICs macrophages were more abundant than lymphocytes with an incremental increase noted with disease progression. CONCLUSIONS: BRCA1/2 mutation carriers exhibited no significant increase in proliferation in the fallopian tube epithelial cells either in the ampulla or fimbriated ends of the tube. Rather, a significant proliferative increase was defined in the cases determined to be in the follicular, or proliferative, preovulatory phase of the ovarian cycle. Finally, we also show an incremental increase in leukocytes invading the STICs and HGSC, implicating a possible role of the leukocytes early in the progression or inhibition of tumor formation, which is independent of ovarian cycle status.

Identification of abrogated pathways in fallopian tube epithelium from BRCA1 mutation carriers.

The discovery of occult invasive and intra-epithelial tubal carcinomas in BRCA1 mutation carriers undergoing prophylactic surgery has implicated the fallopian tube epithelium as the source of serous cancer. However, little is known of the early molecular events of serous oncogenesis, or why cancers in BRCA1 mutation carriers are found preferentially in tissues which are responsive to reproductive hormones. We hypothesize that molecular alterations present in morphologically normal tubal epithelium from BRCA1 heterozygotes reflect the earliest events in serous carcinogenesis and may be markers of increased cancer risk as well as targets for risk reduction. Genetic profiling of microdissected tubal epithelium from histologically normal BRCA1 mutation carriers and controls was performed. We sought to define a signature which differentiated BRCA1 mutant tubal epithelium from women with low risk of developing ovarian cancer. Molecular differences between the follicular and luteal phases were prominent and, by using filtering techniques and a two-way ANOVA without a False Discovery Rate correction, we identified 440 probe sets with a more than two-fold change in gene expression related to BRCA1 mutation status. Using gene ontology and known associations to cancer pathways, we selected five genes for further analysis by qPCR and immunohistochemistry, and were able to demonstrate statistically significant differentiation of BRCA1 and control cases in an independent set of cases. The altered expression profiles in histologically normal tubal epithelium from BRCA1 heterozygotes suggest that these cells may respond differently to microenvironmental stresses.

Low malignant potential tumors with micropapillary features are molecularly similar to low-grade serous carcinoma of the ovary.

OBJECTIVE: Low-grade serous carcinoma (LGSC) is a chemoresistant ovarian neoplasm thought to potentially arise in a background of low malignant potential tumors (LMP), which are typically non-aggressive. However, LMP with micropapillary features (LMP-MP) have more aggressive clinical behavior and may represent an intermediate in progression to LGSC. The objective of this study was to obtain and compare gene expression profiles of LMP, LMP-MP and LGSC to determine if LMP-MP more closely resembles LGSC, and to identify genes involved in LGSC carcinogenesis. METHODS: Epithelial cells from LMP (n=17), LMP-MP (n=9) and LGSC (n=11) were isolated by laser capture microdissection. RNA was extracted, reverse transcribed to cDNA, amplified and hybridized to Affymetrix U133 Plus2 genechip arrays. Gene expression data were checked for quality, filtered and significantly altered genes between subgroups were identified. Differential expression of selected genes was verified by RT-qPCR and immunohistochemistry. RESULTS: Gene expression analysis identified differential expression between LMP and LMP-MP, LMP and LGSC but not LMP-MP and LGSC. Integration of differentially expressed genes into the protein interaction database CytoScape highlighted gene products in the MAPK pathway as differentially regulated between LMP and LGSC. Four genes were selected and validated by RT-qPCR performed on microarray samples (n=15) and immunohistochemistry on a representative microarray (n=57). CONCLUSION: The gene expression profile of LMP-MP is similar to LGSC and distinct from LMP, reflecting their more aggressive clinical behavior. Candidate genes in the MAPK pathway were highlighted which may play a role in LGSC carcinogenesis and indicate potential therapeutic targets.