Abstract P223: Phase 1, first-in-human, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of oral TP-3654, a PIM kinase inhibitor, in patients with advanced solid tumors

Background: Elevated expression of PIM kinases in various solid and hematologic malignancies is correlated with increased cell survival and reduced apoptosis, implicating inhibition of PIM kinases as attractive targets for disruptive therapy. TP-3654 is an oral, small molecule, investigational PIM kinase inhibitor with favorable selectivity against PIM-1 over other kinases. TP-3654 is currently being evaluated in a phase 1 first-in-human study in patients (pts) with advance solid tumors (NCT03715504). Methods: Pts with advanced metastatic, progressive, or unresectable solid tumors refractory or intolerant of established therapies were treated with TP-3654. Pts took TP-3645 orally once (QD) or twice (BID) daily in a 28-day dosing cycle until unacceptable toxicity or disease progression. Escalating dose levels of TP-3654 were evaluated using a 3+3 design. The primary objective was to determine maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs). Secondary objectives included establishing the pharmacokinetic (PK) profile of oral TP-3654 and any evidence of antitumor activity. An exploratory objective was to study predictive biomarkers in tumor tissues and mechanism-based pharmacodynamic activity in peripheral blood mononuclear cells (PBMCs). Results: As of 31 May 2021, 22 pts were treated with TP-3654 at 480 mg QD (n=3), 720 mg QD (n=3), 1080 mg QD (n=4), 1440 mg QD (n=3), 720 mg BID (n=3), and 960 mg BID (n=6). Median age of 58 years (range: 20–72), 59% (13/22) pts male, and 86% (19/22) pts received ≥3 lines of prior therapy. Median treatment duration is 2 cycles (range: 0.1–24) and 6 pts received treatment for ≥4 cycles. Two pts remain on active study treatment. No DLT was observed. The most common treatment-emergent adverse events (TEAEs) reported in ≥20% of pts were vomiting, diarrhea, nausea, and abdominal pain. No related myelosuppressive AEs were reported. Fifty percent (11/22) of pts reported 18 Grade ≥3 TEAEs, of which only one (alanine aminotransferase increased) was considered related to TP-3654. No related, serious AEs were reported. Two TEAEs resulted in a fatal outcome (acute kidney injury, completed suicide); neither were related to TP-3654. Best response is stable disease (SD) in 67% (10/15) evaluable pts, SD for ≥ 16 weeks in 5 pts, best reduction of tumor size from baseline is -22%. TP-3654 plasma exposure increased with doses up to 1080 mg QD; the BID regimen at the 720 mg dose achieved greater plasma exposure than the 1440 mg QD dosing regimen. Reduced phosphorylation of PIM-1 downstream signal protein pBAD was observed in isolated PBMCs, predominantly in pts with prolonged clinical benefit. Conclusions: Preliminary data suggest that TP-3654 is tolerated as a monotherapy up to 960 mg BID in pts with heavily pretreated, relapsed, and refractory solid tumors. No DLT was observed and MTD was not reached. PK data indicate that the BID dose regimen achieved better plasma exposure than the QD regimen at higher doses. TP-3654 has shown target-specific inhibition of PIM-1 in pts. Updated data will be presented.

Citation Format: Ignacio Garrido-Laguna, Patrick M. Dillon, Sujan Kabir, Jian Mei, Mark L. Wade, Huyuan Yang, Carl Stapinski, Jason M. Foulks, Steven L. Warner, Clifford Whatcott, Claudia Lebedinsky, Siqing Fu. Phase 1, first-in-human, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of oral TP-3654, a PIM kinase inhibitor, in patients with advanced solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P223.

Abstract 606: Pkm2 activation modulates the tumor-immune microenvironment and enhances response to checkpoint inhibitors in preclinical solid tumor models

Pyruvate kinase is a crucial enzyme responsible for the last step of glycolysis. Cancer cells can use the M2 isoform of pyruvate kinase (PKM2), to better balance respiration and biosynthesis due to allosteric switching between the less active dimeric and fully active tetrameric forms. Additionally, the dimeric form of PKM2 can translocate to the nucleus, altering transcription to enhance cancer cells' ability to grow and evade immune detection. Inducing tetramerization presents an opportunity to target PKM2 resulting in the metabolic reprogramming of tumor-immune microenvironment (TME). TP-1454 is a potent PKM2 activator with low nanomolar PKM2 activation in biochemical assays (AC50 = 10 nM) and multiple cell types (AC < 50 nM), tolerated in mice, rats and dogs after repeat doses as high as 1000 mg/kg/day and has recently entered a Phase I clinical trial (NCT04328740).

We hypothesize that PKM2 activation may reverse the immune-suppressive TME. To test this hypothesis, we examined the activity of TP-1454 combination with immunotherapy (I/O) in multiple mouse syngeneic tumor models. TP-1454 and anti-PD-1 combination therapy in colorectal cancer models resulted in tumor growth inhibition versus vehicle (53% in CT26; 99% in MC38, P < 0.001). We observed decreases in multiple glycolytic intermediates in TP-1454-treated tumors versus vehicle. We conducted immunophenotyping of the TME in multiple models to identify targets of PKM2 activation. TP-1454 treatment reduced the CD4+ Foxp3+ T-regulatory (Treg) population in MC38, 4T1, RENCA models. Further, we assayed TP-1454 induced PKM2 activation in different immune cell types. To confirm the effect of PKM2 activation on Treg cells we conducted an in vitro assay to explore TP-1454 treatment response on polarization of Tregs and/or toxicity and proliferation. We further utilized LCMS to explore metabolic intermediates that play a critical role in Treg regulation, including regulation of the O-linked β-N-acetylglucosamine (O-GlcNac) post-translational modification, which is reported to stabilize Foxp3 in CD4+ cells. We are currently exploring the effect of TP-1454 treatment on O-GlcNac of Foxp3 and its stability in HEK293 cells, to support the link between PKM2 activation and stabilization of Foxp3.

TP-1454 effects on tumor-specific immunity were validated using tumor rechallenge studies. The results of a tumor rechallenge study will be presented using murine MC38 or RENCA xenograft models that are treated with TP-1454 and I/O combination therapies that exhibited a complete response (CR) and were re-implanted.

These preclinical studies indicate a unique mechanism modulating tumor metabolism and the TME to improve the response of cancer patients to immunotherapy.

Citation Format: Salah Sommakia, Satya Pathi, Yuta Matsumura, Curtis Allred, Ethika Tyagi, Matthew Lalonde, Jason Foulks, Adam Siddiqui, Clifford Whatcott, David Bearss, Steven Warner. Pkm2 activation modulates the tumor-immune microenvironment and enhances response to checkpoint inhibitors in preclinical solid tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 606.

Abstract 1345: Pharmacodynamic biomarkers for Pim inhibition with TP-3654 in patients with solid tumors

Proviral integration site for Moloney murine leukemia virus-1 (Pim-1) is a serine/threonine kinase downstream of Jak/Stat signaling which promotes cell growth, survival, and drug resistance. Pim-1 kinase is an important driver of tumorigenesis and tumor survival through its role in a number of downstream pathways, including inhibition of apoptosis through phosphorylation of the BH3-only protein BAD. Pim-1 is expressed at very low levels in most normal tissues, but is overexpressed in many cancers, such as prostate, colorectal, and many hematologic malignancies. Pim-1 kinase activity is constitutive and therefore directly proportional to protein expression. As such, Pim-1 is an attractive therapeutic target. TP-3654 is a second-generation, oral Pim inhibitor currently in Phase I clinical trials in solid tumors and myelofibrosis (NCT03715504 and NCT04176198). TP-3654 inhibits all three Pim kinases, with Ki values for Pim-1 (5nM), and Pim-2 and Pim-3 &lt250 nM in a biochemical assay. Treatment with TP-3654 in Jurkat and HEL cell lines showed dose-dependent modulation of the downstream targets of PIM, such as pS6K and pBad. A dose-dependent increase of TP-3654 Cmax was observed in plasma and subcutaneous PC-3 xenograft tumors in animals dosed orally at 50, 100 and 200 mg/kg with Tmax at 1 hour. Animals bearing HEL tumors were dosed similarly and Cmax values increased in a dose-dependent manner with Tmax at 2 hours. Plasma and tumor TP-3654 concentrations were above the measurement threshold out to 24 hours post dose. We further explored pharmacodynamic biomarkers of Pim inhibition (pBad, pS6K, and pS6RP) in flash frozen (FF) tumor tissue at various time points in both models by western blot and saw a maximum of 40% decrease in phosphorylated S6K at 2 hours, and an 80% decrease in pBad at 8 hrs in PC3 xenograft tumors in mice treated with 100 mg/kg of TP-3654. We hypothesized that treatment with TP-3654 would modulate Pim signaling in both cancer cells and peripheral blood mononuclear cells (PBMCs). This allows for detection of pharmacodynamic markers using repeated peripheral blood draws instead of invasive biopsies. We treated PBMCs from multiple healthy human donors with TP-3654 ex vivo at 0.3 and 3 µM to assess the movement of Pim biomarkers. Two phosphorylation markers, pS6K and pS6RP consistently exhibited dose-dependent decreases (30-70%) as measured by western blot. Inhibition of pBad was dependent on pretreatment phosphorylation state. These results were confirmed in an automated western blot system.

Citation Format: Curtis A. Allred, Yuta Matsumura, Ethika Tyagi, Mark Wade, Clifford Whatcott, Jason Foulks, Adam Siddiqui, David J. Bearss, Steven L. Warner. Pharmacodynamic biomarkers for Pim inhibition with TP-3654 in patients with solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1345.

A phase I, first-in-human, open-label, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of oral TP-1287 administered daily to patients with advanced solid tumors

3611

Background: TP-1287 is a an orally bioavailable phosphate prodrug of alvocidib, a cyclin dependent kinase 9 (CDK9) inhibitor. TP-1287 exhibits potent inhibition of intracellular kinases including CDK9. Inhibition of CDK9 leads to downregulation of the BCL-2 family member, MCL-1, which in turn inhibits tumor growth in preclinical animal models of prostate, breast, and lung carcinomas. Methods: This is a multicenter, Phase 1, dose escalation study using a standard 3+3 design with a modified Fibonacci scheme to examine the safety and clinical activity of TP-1287 in patients with advanced solid tumors. Patients will be added at the maximum tolerated dose (i.e. expansion cohort) to test TP-1287 as a single agent in patients with castrate resistant prostate cancer. Results: Twenty-two patients who were enrolled between December 2018 and January 2020 received a range of doses from 1 mg QD to 11 mg BID over 7 cohorts. Data are available for 20 patients as of the data cutoff date. TP-1287 plasma PK Cmax and AUC increased in near linear fashion over cohorts 1 thru 6, reaching 80 ng/mL and 499.3 ng*h/mL in cohort 6 for Cmax and AUC, respectively. TP-1287 treatment resulted in dose-dependent reductions of phospho-RNA Pol II, consistent with CDK9 inhibition, as measured by a flow cytometric assay assessing pharmacodynamic changes in phosphorylation state in PBMCs. The most frequently observed Grade 3 AE was unrelated anemia in 2 patients. All other events of Grade 3 (9 events/7 patients) and Grade 4 (1 event/seizure with new CNS mets) were unlikely related or unrelated. Clinical benefit was seen in one sarcoma patient with PR (15+cycles), one RCC patient with SD (7+cycles) and 2 bladder cancer patients with SD (6 and 8 cycles). Conclusions: These findings suggest that TP-1287 is tolerated as a monotherapy in patients with heavily pretreated, relapsed, refractory solid tumors and further clinical development in selected indications is warranted. Clinical trial information: NCT03298984 .

A phase I, first-in-human, open-label, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of oral TP-3654 administered daily for 28 days to patients with advanced solid tumors

3586

Background: TP-3654 is an oral, second generation, potent PIM-1 kinase inhibitor with activity against PIM 2, 3 and favorable selectivity against other kinases. These cytoplasmic serine/threonine kinases are highly expressed in many cancers and their oncogenic potential has been largely attributed to supressing apoptosis downstream of stimuli including inflammatory cytokines and other immune effectors. TP-3654 has efficacy in various hematologic and solid tumor models inducing stromal Pim-1 also has been shown to mediate various aspects of the tumor microenvironment. Thus, Pim kinases are attractive targets for the treatment of many human malignanices. Methods: A first in human, multicenter, phase 1, dose escalation study using a standard 3+3 design with a modified Fibonacci scheme to examine the safety and clinical activity of TP-3654 in patients with advanced solid tumors. Results: Ten patients were enrolled between 30Apr and 31Dec2019 receiving 480, 720, and 1080 mg respectively. Grade 3 AEs were scrotum wound infection, altered mental status, anemia, fall, and lower extremity edema, none were related to study drug and all were manageable with supportive care. There were no Grade 4 or 5 AEs and no DLTs. Median duration of SD was 5.5 months (6/10) and with prolonged SD > 16wks (4/10). One CRC patient with 4 lines of prior therapy had a 22% reduction in tumor volume (SD > 5+ mos). TP-3654 plasma PK values (Cmax, AUC) continuously increased through all 3 cohorts. Average Cmax (ng/mL) and AUC0-24 (ng*hours/mL) were 195, 1965 (480mg); 357, 3310 (720mg); 735, 6922 (1080mg), respectively. PK values increased linearly with higher doses without reaching saturation. Peripheral Blood Mononuclear Cells were isolated from subjects prior and up to 24hours after treatment. Western Blot from protein lysates revealed a decrease in phosphorylation of BAD and p70s6K proteins, both regulated by PIM-1 kinase. Conclusions: These findings suggest that TP-3654 is tolerated as a monotherapy in patients with heavily pretreated, relapsed, and resistant solid tumors warranting further clinical development in selected indications.

Targeting AXL-JAK1 in tumor and immune ecosystem of lung cancer

Intercellular crosstalk between lung adenocarcinoma cells (LACs) and tumor-associated macrophages (TAMs) has been implicated in promoting cancer metastasis; however, how oncogenic signaling networks corroborate in this tumorigenic process remains unexplored. Our findings suggest that coordinated activation of AXL and JAK1-pSTAT3 signaling engenders a vicious cycle of dependence between LACs and TAMs for tumor progression. AXL-overexpressing LACs polarize TAMs to an M2-like phenotype in a JAK1-STAT3-dependent manner, facilitating the development of a proinflammatory tumor microenvironment. Conversely, M2-like TAMs release Gas6 ligand to enhance AXL-mediated cancer stemness and epithelial-to-mesenchymal transition (EMT) in LACs. Cytometry by time-of-flight (CyTOF) is a single-cell detection technology that allows for measurement of multiple protein markers in diverse cell subpopulations. We designed a 34-antibody CyTOF panel to identify immune cells, stromal cells, epithelial cells, oncogenic signaling, stemness and EMT components for LAC tumor profiling. CyTOF profiling of ~642,241 single cells detected 55 subpopulations among LAC cell lines (n=4 with co-culture conditions) and lung tumors (n=12), which were further differentiated based on their cell types (LACs, TAMs, stromal cells, granulocytes, natural killer, B and T lymphocytes). High AXL expression was noticed in tumor cell subpopulation while high pSTAT3 expression was detected in the TAM subpopulation. Moreover, pSTAT3 expression levels were increased in U937 differentiated macrophage after co-culture with A549 cells. This novel platform may facilitate the optimal selection of lung cancer patients for dual targeting of AXL and JAK1-pSTAT3.

Combined venetoclax and alvocidib in acute myeloid leukemia

More effective treatment options for elderly acute myeloid leukemia (AML) patients are needed as only 25-50% of patients respond to standard-of-care therapies, response duration is typically short, and disease progression is inevitable even with some novel therapies and ongoing clinical trials. Anti-apoptotic BCL-2 family inhibitors, such as venetoclax, are promising therapies for AML. Nonetheless, resistance is emerging. We demonstrate that venetoclax combined with cyclin-dependent kinase (CDK) inhibitor alvocidib is potently synergistic in venetoclax-sensitive and -resistant AML models in vitro, ex vivo and in vivo. Alvocidib decreased MCL-1, and/or increased pro-apoptotic proteins such as BIM or NOXA, often synergistically with venetoclax. Over-expression of BCL-XL diminished synergy, while knock-down of BIM almost entirely abrogated synergy, demonstrating that the synergistic interaction between alvocidib and venetoclax is primarily dependent on intrinsic apoptosis. CDK9 inhibition predominantly mediated venetoclax sensitization, while CDK4/6 inhibition with palbociclib did not potentiate venetoclax activity. Combined, venetoclax and alvocidib modulate the balance of BCL-2 family proteins through complementary, yet variable mechanisms favoring apoptosis, highlighting this combination as a promising therapy for AML or high-risk MDS with the capacity to overcome intrinsic apoptosis mechanisms of resistance. These results support clinical testing of combined venetoclax and alvocidib for the treatment of AML and advanced MDS.

Abstract IA29: Identifying epithelial morphogenesis inhibitors in neural crest development and cancer

The epithelial to mesenchymal transition (EMT) is a highly conserved morphogenesis program that is essential for re-shaping and mobilizing epithelial cells during gastrulation, neural crest development and tissue regeneration. In cancer cells, EMT induction promotes acquisition of invasive cellular morphologies, stem cell-like properties and pro-survival mechanisms, which contribute to disease progression, therapy resistance and decreased overall survival. The identification of compounds that block or reverse EMT therefore represents an important therapeutic strategy to prevent cancer invasion and eradicate disseminated tumor cells. Unfortunately, current EMT inhibitors have shown limited clinical benefit, in part due to an incomplete understanding of the molecular mechanisms controlling EMT in development and cancer as well as a lack of screening platforms that recapitulate the complex physiological environment of EMT in the living animal. To overcome these obstacles, we have established a zebrafish Snail1-GFP lineage reporter strain to label dorsal neural tube progenitor cells before they undergo EMT to become neural crest, which allows us to visualize epithelial morphogenesis independent of later cell migration events. Thousands of Snail1-GFP embryos can be easily generated to perform whole animal-based screens with small molecule libraries to identify compounds that inhibit EMT in vivo. Our initial screening results using previously characterized EMT inhibitors showed that many compounds inhibited neural crest migration after EMT had occurred, but only one compound, an AXL receptor tyrosine kinase inhibitor called TP-0903, inhibited both epithelial morphogenesis and neural crest migration. TP-0903 significantly decreased twist1a expression, a canonical EMT transcription factor and blocked down-regulation of epithelial Cadherins. RNA-Seq analysis and chemical rescue experiments revealed that TP-0903 acts by inducing retinoic acid (RA) biosynthesis and triggering a RA-mediated transcriptional program. TP-0903 treatment of a number of human cell lines and mouse xenograph tumors showed that TP-0903 also inhibits EMT programs and survival in human cancer cells. These studies demonstrate the value and feasibility of using zebrafish neural crest development to identify effective EMT compounds in vivo. As such, we have identified TP-0903 as a new potential therapeutic for inhibiting EMT in cancer, and our findings support the hypothesis that RA-induced inhibition of EMT contributes to its current success in treating minimal residual disease in humans.

Citation Format: Laura Jimenez, Clifford Whatcott, Jindong Wang, Steven Warner, Monique Morrison, David Bearss, Rodney A. Stewart. Identifying epithelial morphogenesis inhibitors in neural crest development and cancer. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr IA29.

Phenotypic chemical screening using a zebrafish neural crest EMT reporter identifies retinoic acid as an inhibitor of epithelial morphogenesis

The epithelial-to-mesenchymal transition (EMT) is a highly conserved morphogenetic program essential for embryogenesis, regeneration and cancer metastasis. In cancer cells, EMT also triggers cellular reprogramming and chemoresistance, which underlie disease relapse and decreased survival. Hence, identifying compounds that block EMT is essential to prevent or eradicate disseminated tumor cells. Here, we establish a whole-animal-based EMT reporter in zebrafish for rapid drug screening, called Tg(snai1b:GFP), which labels epithelial cells undergoing EMT to produce sox10-positive neural crest (NC) cells. Time-lapse and lineage analysis of Tg(snai1b:GFP) embryos reveal that cranial NC cells delaminate from two regions: an early population delaminates adjacent to the neural plate, whereas a later population delaminates from within the dorsal neural tube. Treating Tg(snai1b:GFP) embryos with candidate small-molecule EMT-inhibiting compounds identified TP-0903, a multi-kinase inhibitor that blocked cranial NC cell delamination in both the lateral and medial populations. RNA sequencing (RNA-Seq) analysis and chemical rescue experiments show that TP-0903 acts through stimulating retinoic acid (RA) biosynthesis and RA-dependent transcription. These studies identify TP-0903 as a new therapeutic for activating RA in vivo and raise the possibility that RA-dependent inhibition of EMT contributes to its prior success in eliminating disseminated cancer cells.

Editors' choice: Generation and characterization of a novel neural crest EMT reporter for rapid in vivo drug screening in zebrafish that identifies a small-molecule EMT inhibitor that blocks this process by activating retinoic acid signaling.

Abstract C138: Targeting macropinocytosis in pancreatic cancer

Pancreatic cancer is the fourth-leading cause of cancer-related deaths in the United States with a 5-year survival rate of <5%. The deadly nature of this disease compounded by a lack of effective treatment options highlights a need for new therapeutics. Past studies have suggested that pancreatic cancer cells acquire the nutrients needed for cell growth through macropinocytosis, an endocytic process by which protrusions from the cell membrane create large vesicles that transport extracellular fluid along with the constituent proteins and lipids into the cell. Additionally, several studies have suggested that macropinocytosis is regulated in part by various genes including p21 protein (Cdc42/Rac)-activated kinase1 (PAK1), ADP-ribosylation factor 6 (ARF6), and sorting nexin 5 (SNX5). In this study, we investigated the effects of knockdown of these three genes on the macropinocytic activity of pancreatic cancer cells. The goal of this study is to assess whether PAK1, ARF6, or SNX5 may serve as potential targets for the suppression of macropinocytosis in pancreatic cancer, which would hamper the cells' uptake of nutrients thus starving the cancer cells and hindering tumor growth. We carried out this study using MIA PaCa-2 pancreatic cancer cells, which are known to exhibit relatively high levels of macropinocytosis. Treatment of cells with siRNA sequences specific to the three genes resulted in a significantly decreased uptake of FITC-labeled dextran as compared to cells treated with non-targeting siRNA and cells that received no treatment, indicating that inhibiting the expression of each of the genes correlates to a reduction in macropinocytic activity. Among the three genes, PAK1 siRNAs exhibited the most significant and consistent inhibitory effect on macropinocytic activity of MIA PaCa-2 cells. We, therefore, further tested the effect of two small-molecule PAK1 inhibitors, namely IPA-3 and PF-03758309, on macropinocytosis. Treatment of cells with the inhibitors resulted in a dose-dependent decrease in the uptake of FITC-labeled dextran and FITC-labeled albumin. The inhibitors also showed potent anti-proliferative activity in pancreatic cancer cell lines. The results of this study indicate that inhibition of PAK1, ARF6, or SNX5 all resulted in reduced macropinocytic activity of pancreatic cancer cells, with PAK1 showing the most promise as a potential therapeutic target for pancreatic cancer.

Citation Format: James Hunt, Serina Ng, Clifford Whatcott, Daniel D. Von Hoff, Haiyong Han. Targeting macropinocytosis in pancreatic cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C138.

Tumor-stromal interactions in pancreatic cancer

The tumor associated stroma has been described in recent years as being complicit in tumor growth in pancreatic cancer. The stroma hosts a variety of components of both cellular and molecular makeup. In normal tissues, the stroma provides nutrients and regulatory signals for proper cellular polarity and function. However, following oncogenic transformation, the stromal compartment is conscripted to provide stimulatory signals and protection to tumor cells. It is these tumor-stromal interactions that are currently of great therapeutic interest. Several key reports have suggested that therapeutic targeting of the tumor-stromal interactions in pancreatic cancer has the potential to offer survival benefit. In this review, we will discuss the tumor-stromal interactions that contribute to tumor growth and progression, and ways in which we might counter these interactions.

Abstract 2601: ROCK1 as a potential therapeutic target in pancreatic cancer

ROCK1, or Rho-associated coiled coil-containing protein kinase 1, is a multifunctional member of the AGC (protein kinase A/G/C) kinase family that has been implicated in the modulation of stress-fiber assembly, cell-cell adhesion, cell contraction, apoptosis, cytokinesis, and in the migration and invasion of multiple cell types. Increased ROCK1 expression has been observed in a number of pathological conditions, including cancer. We identified a low frequency (4/34) amplification of the ROCK1 gene locus at chromosome 18q11.1 in pancreatic ductal adenocarcinoma (PDA) patient tissue samples by aCGH analysis. We therefore hypothesized that ROCK1 might play an important role in pancreatic cancer progression, and may serve as a suitable target in pancreatic cancer treatment. Consistent with findings in other tumor types, we observed increased expression of ROCK1 in pancreatic epithelial cells relative to the surrounding stromal cells, or adjacent normal pancreatic ductal cells, in an immunohistochemical (IHC) analysis of a pancreatic cancer tissue array. In our study, 76% (53/70) of tumor samples exhibited 2+ or greater (scale 0-3+) in staining intensity by IHC analysis, versus 40% (19/47) of adjacent normal tissue samples (P<0.0001). This same increased expression of ROCK1 in cancer cells was also observed in a coculture model of human PDA cells and primary myofibroblast cells derived from PDA tissues. Inhibition of ROCK kinase activity by small molecule inhibitors (Fasudil and Y27632) demonstrated moderate (IC50s range from 2-30 μM) inhibition of PDA cell proliferation. An increased sensitivity to ROCK1 inhibition was observed in PDA myofibroblasts, which corresponded with a decreased expression of Collagen I. These results suggest that ROCK1 may play a role in pancreatic cancer, both in the proliferation of tumor epithelial cells, as well as the development of the stromal compartment. Based on these findings we feel that ROCK1 is a potential therapeutic target in both the tumor and stromal cells in pancreatic cancer, and may provide an effective means to enhance current treatment regimens.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2601. doi:10.1158/1538-7445.AM2011-2601

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry protocol for monitoring the progress of enzymatic 13C/15N-labeled DNA syntheses

We demonstrate that a simple matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry protocol provides a rapid and accurate method for monitoring the stage and completeness of enzymatic DNA syntheses. A crucial step of these syntheses is to quench the reaction at the desired nucleotide length. This is especially important when expensive, e.g., (13)C/(15)N-labeled DNA segments, are synthesized for multinuclear magnetic resonance purposes to reveal detailed structural information. The analyses of three templates for a human telomeric 22-mer, a wild type, and a mutant human c-MYC promoter (18- and 22-mer) DNA and their reactions with the 3'-5' exo(-) Klenow fragment of DNA polymerase I demonstrate the usefulness of our protocol. Small amounts of samples (ca. 1-2 microl each) were taken from the reaction mixtures at different times and analyzed promptly by MALDI-TOF, applying our successive on-plate desalting method that eliminates the insensitivity of the MALDI technique at high salt content. The progress of the reaction was detected by monitoring the relative intensity ratios of ions corresponding to the desired products and the primer-template complexes. The effectiveness of NH(3) cleavage leading to final products was also followed by MALDI-TOF in successful enzymatic reactions.