Sheldon L. Holder

Characterization of a potent and selective small-molecule inhibitor of the PIM1 kinase.

The pim-1 kinase is a true oncogene that has been implicated in the development of leukemias, lymphomas, and prostate cancer, and is the target of drug development programs. We have used experimental approaches to identify a selective, cell-permeable, small-molecule inhibitor of the pim-1 kinase to foster basic and translational studies of the enzyme. We used an ELISA-based kinase assay to screen a diversity library of potential kinase inhibitors. The flavonol quercetagetin (3,3′,4′,5,6,7-hydroxyflavone) was identified as a moderately potent, ATP-competitive inhibitor (IC50, 0.34 μmol/L). Resolution of the crystal structure of PIM1 in complex with quercetagetin or two other flavonoids revealed a spectrum of binding poses and hydrogen-bonding patterns in spite of strong similarity of the ligands. Quercetagetin was a highly selective inhibitor of PIM1 compared with PIM2 and seven other serine-threonine kinases. Quercetagetin was able to inhibit PIM1 activity in intact RWPE2 prostate cancer cells in a dose-dependent manner (ED50, 5.5 μmol/L). RWPE2 cells treated with quercetagetin showed pronounced growth inhibition at inhibitor concentrations that blocked PIM1 kinase activity. Furthermore, the ability of quercetagetin to inhibit the growth of other prostate epithelial cell lines varied in proportion to their levels of PIM1 protein. Quercetagetin can function as a moderately potent and selective, cell-permeable inhibitor of the pim-1 kinase, and may be useful for proof-of-concept studies to support the development of clinically useful PIM1 inhibitors. [Mol Cancer Ther 2007;6(1):163–72]

Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer: A Systematic Review and Two-Step Meta-Analysis

BACKGROUND Platinum-based neoadjuvant chemotherapy has been shown to improve survival outcomes in muscle-invasive bladder cancer patients. We performed a systematic review and meta-analysis to provide updated results of previous findings. We also summarized published data to compare clinical outcomes of methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) versus gemcitabine and cisplatin/carboplatin (GC) in the neoadjuvant setting. METHODS A meta-analysis of 15 randomized clinical trials was performed to compare neoadjuvant chemotherapy plus local treatment with the same local treatment alone. Because no randomized trials have investigated MVAC versus GC in the neoadjuvant setting, a meta-analysis of 13 retrospective studies was performed to compare MVAC with GC. RESULTS A total of 3,285 patients were included in 15 randomized clinical trials. There was a significant overall survival (OS) benefit associated with cisplatin-based neoadjuvant chemotherapy (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.79-0.96). A total of 1,766 patients were included in 13 retrospective studies. There was no significant difference in pathological complete response between MVAC and GC. However, GC was associated with a significantly reduced overall survival (HR, 1.26; 95% CI, 1.01-1.57). After excluding carboplatin data, GC still seemed to be inferior to MVAC in OS (HR, 1.31; 95% CI, 0.99-1.74), but the difference was no longer statistically significant. CONCLUSION These results support the use of cisplatin-based combination neoadjuvant chemotherapy in muscle-invasive bladder cancer. Although GC and MVAC had similar treatment response rates, the different survival outcome observed in this study requires further investigation. IMPLICATIONS FOR PRACTICE Platinum-based neoadjuvant chemotherapy (NCT) has been shown to improve survival outcomes in muscle-invasive bladder cancer (MIBC) patients, but the optimal neoadjuvant regimen has not been established. Methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) and gemcitabine and cisplatin/carboplatin (GC) are two of the most commonly used chemotherapy regimens in modern oncology. In this two-step meta-analysis, an updated and more precise estimate of the survival benefit of cisplatin-based NCT in MIBC is provided. This study also demonstrated that MVAC might have superior overall survival compared with GC (with or without carboplatin data) in the neoadjuvant setting. The findings suggest that NCT should be standard care in MIBC, and MVAC could be the preferred neoadjuvant regimen.

A multiplexed marker-based algorithm for diagnosis of carcinoma of unknown primary using circulating tumor cells

Real-time, single-cell multiplex immunophenotyping of circulating tumor cells (CTCs) is hypothesized to inform diagnosis of tissue of origin in patients with carcinoma of unknown primary (CUP). In 20 to 50% of CUP patients, the primary site remains unidentified, presenting a challenge for clinicians in diagnosis and treatment. We developed a post-CellSearch CTC assay using multiplexed Q-dot or DyLight conjugated antibodies with the goal of detecting multiple markers in single cells within a CTC population. We adapted our approach to size-based CTC enrichment protocols for capturing CTCs and subsequent immunofluorescence (IF) using a minimal set of markers to predict the primary sites for common metastatic tumors. The carcinomas are characterized with cytokeratin 7 (CK7), cytokeratin 20 (CK20), thyroid transcription factor 1 (TTF-1), estrogen receptor (ER) or prostate-specific antigen (PSA. IF has been optimized in cultured tumor cells with individual antibodies, then with conjugated antibodies to form a multiplex antibody set. With IF, we evaluated antibodies specific to these 5 markers in lung, breast, colorectal, and prostate cancer cell lines and blood from metastatic prostate and breast cancer patients. This advanced technology provides a noninvasive, diagnostic blood test as an adjunct to routine tissue biopsy. Its further implementation requires prospective clinical testing.

PIM1 Kinase as a Target in Prostate Cancer: Roles in Tumorigenesis, Castration Resistance, and Docetaxel Resistance

PIM1 kinase is a serine/threonine kinase that has been shown to be overexpressed in multiple human malignancies, including prostate cancer. PIM1 phosphorylates multiple cellular substrates to inhibit apoptosis and promote cell cycle progression. Increased PIM1 can also facilitate genomic instability to promote neoplastic processes. PIM1 kinase is overexpressed in high-grade prostate intraepithelial neoplasia and in prostate cancer compared to normal prostatic tissue and benign prostate hyperplasia. Elevated PIM1 levels have been shown to be the direct result of oncogenic fusion proteins and active signal transduction pathways. In vitro and in vivo mouse studies indicate that PIM1 is weakly tumorigenic but synergizes dramatically when coexpressed with MYC. PIM1 kinase can also phosphorylate the androgen receptor (AR), thereby regulating AR degradation and function, in a low androgen environment. This finding implicates PIM1 in castration -resistant prostate cancer. Furthermore, expression of PIM1 has been shown to be increased in prostate tissue after docetaxel exposure, conferring partial resistance to docetaxel. Correlatively, decreased PIM1 levels sensitize prostate cancer cells to docetaxel treatment. Thus, PIM1 may be a target in docetaxel resistant disease. In summary, PIM1 kinase is involved in prostate tumorigenesis, castration resistance, and docetaxel resistance. Several PIM1 kinase inhibitors have been reported and are in varied stages of drug development. PIM1 is involved in multiple processes in the development and propagation of prostate cancer, thus a PIM1 kinase inhibitor may serve as an effective therapeutic agent in this prevalent disease.

Therapeutic approach guided by genetic alteration: use of MTOR inhibitor in renal medullary carcinoma with loss of PTEN expression.

Renal Medullary Cancer (RMC) is a rare and aggressive type of renal cell cancer that presents predominantly in patients with sickle cell hemoglobinopathies, and is typically metastatic at the time of presentation. Although platinum based chemotherapeutic regimens have recently emerged as the best option for producing a clinically significant response as reported in various case series, the response is far from satisfactory, as most RMC patients still succumb to their disease within a year of diagnosis. There is currently no standard of care for treatment of this disease. We report, to our knowledge, the first case of RMC where in molecular characterization of the tumor was used to guide therapy. In our patient, molecular analysis identified a decreased expression of Ribonucleotide Reductase M1(RRM1) and phosphatase and tensin homolog (PTEN). Based on these results of PTEN deficiency, we started our patient on everolimus (an MTOR inhibitor) maintenance after treating him with an induction chemotherapy regimen of Paclitaxel-Cisplatin-Gemcitabine (PCG). His tumor responded to induction therapy and he went into complete remission and remained in remission for 7 months. He is now alive about 14 months from his diagnosis and is asymptomatic with minimal disease. The rarity of RMC makes it very difficult to do any meaningful clinical trials in this group of patients. The overall prognosis for RMC remains very poor and knowledge about driver mutations may help in guiding therapy to improve survival in this select group of patients, where there is dearth of available therapies.

Dexamethasone may be the most efficacious corticosteroid for use as monotherapy in castration-resistant prostate cancer

Corticosteroids have been used in the therapy for castration-resistant prostate cancer (CRPC) for decades, both as monotherapy and in combination with additional agents. In this article the authors report the results of a phase II trial of dexamethasone versus prednisolone as monotherapy for CRPC. The study suggests improved PSA and radiographic response rates as well as improved time to PSA progression for dexamethasone over prednisolone therapy; however the differences only trend toward statistical significance. Nonetheless, in light of these data, when treating patients with corticosteroid monotherapy for CRPC it may be prudent to consider using daily dexamethasone over prednisone/prednisolone.

Relationship of smoking status to genomic profile, chemotherapy response and clinical outcome in patients with advanced urothelial carcinoma

Smoking has been linked to urothelial carcinoma (UC), but the implications on genomic profile and therapeutic response are poorly understood. To determine how smoking history impacts genomic profile and chemotherapy response, clinicopathologic data was collected for patients with metastatic UC (mUC) across 3 academic medical centers and comprehensive genomic profiling (CGP) was performed through a CLIA-certified lab. Unsupervised hierarchical clustering based on smoking status was used to categorize the frequency of genomic alterations (GAs) amongst current smokers (CS), ex-smokers (ES) and non-smokers (NS), and survival was compared in these subsets. Fishers exact test identified significant associations between GAs and smoking status. Amongst 83 patients, 23%, 55% and 22% were CS, ES, and NS, respectively, and 95% of patients had stage IV disease. With a median follow up of 14.4 months, the median overall survival (OS) was significantly higher in NS and ES (combined) as compared to CS (51.6 vs 15.6 months; P = 0.04). Of 315 cancer-related genes and 31 genes often related to rearrangement tested, heatmaps show some variations amongst the subsets. GAs in NSD1 were more frequent in CS as compared to other groups (P < 0.001). CS status negatively impacts OS in patients with mUC and is associated with genomic alterations that could have therapeutic implications.

Molecular Characterization of Bladder Cancer in Smokers versus Nonsmokers

Smoking is considered an important risk factor for bladder cancer (BC), yet molecular characterization of BC in nonsmokers has not been extensively studied. Here, we compare molecular differences between smokers and nonsmokers with BC. BC specimens (676) profiled at a Clinical Laboratory Improvement Amendments-certified laboratory from 2006 to 2014 were retrospectively evaluated for molecular differences between smokers and nonsmokers. Protein expression was determined with immunohistochemistry. In situ hybridization was used for ERBB2 (HER2/neu) and EGFR evaluation. Genes were evaluated using Sanger or next-generation sequencing. Thirty patients were confirmed lifetime nonsmokers (NS) and 39 were reformed or current smokers (RCS). There was a trend for increased PIK3CA mutations in NS versus RCS (43% vs 11%, p=0.1760), whereas TP53 alterations were higher in RCS versus NS (63% vs 53%, p=0.6699). EGFR amplification was observed more in NS versus RCS (22% vs 11%, p=0.5815), while HER2 was amplified only in RCS (23% vs 0%, p=0.05). The molecular differences between RCS and NS with BC suggest a different oncogenesis with potentially different treatment options. PATIENT SUMMARY Bladder cancer patients with no history of smoking have different molecular characteristics than those with smoking history. We found that smokers tend to have higher incidence of HER2 amplification, whereas nonsmokers seemed to have higher PIK3CA mutation. This knowledge provides essential information, which can bear relevance to treatment options.

Mitotic activity in non-invasive papillary urothelial carcinoma: its value in predicting tumor recurrence, and comparison to the contemporary two-tier grading system

Measures of mitotic activity predict behavior of noninvasive papillary urothelial carcinoma of the urinary bladder, but it is unclear what role these should have in tumor grading. In this article, we compare measures of mitotic activity to contemporary tumor grading, specifically in their association with recurrence of noninvasive papillary urothelial carcinoma. The study uses a retrospective cohort of 199 tumors from 124 patients. Mitotic activity was treated as a categorical variable (mitotic-inert, mitotic-low, or mitotic-high). Evaluating only first-occurrence tumors, recurrence was more frequent in mitotic-high (hazard ratio [HR], 8.8; P < .0001, Cox model) and mitotic-low tumors (HR, 3.7; P = .017) compared with mitotic-inert tumors, when controlling for treatment with intravesical bacillus Calmette-Guerin, age, and sex. Recurrence was likewise more frequent in high-grade tumors (HR, 3.1; P = .00019, Cox model) compared with low-grade tumors, controlling for these factors. However, mitotic group, but not tumor grade, was significantly associated with recurrence in a multivariate Cox model including mitotic group, tumor grade, and treatment status (HR, 6.5 [P = .0025] for mitotic-high versus reference; HR, 3.7 [P = .018] for mitotic-low versus reference). Frailty models including both first-occurrence and recurrent tumors showed similar results. Isolating the analysis to first occurrence, low-grade tumors, recurrence was more frequent in mitotic-high (HR, 6.8; P = .0044, Cox model) and mitotic-low (HR, 3.4; P = .027) tumors compared with mitotic-inert tumors. The findings indicate that mitotic activity is associated with behavior of noninvasive papillary urothelial carcinoma and may be valuable as an adjunct to the contemporary grading system.

The addition of abemaciclib to sunitinib induces regression of renal cell carcinoma xenograft tumors

Multiple therapies currently exist for renal cell carcinoma, however, most do not result in cure and the development of acquired resistance is the rule rather than the exception. CDK4/6 and PIM1 kinases are potential new therapeutic targets in RCC. Abemaciclib is a potent CDK4/6 and PIM1 kinase inhibitor, thus we evaluated the effects of abemaciclib on renal cell carcinoma. In vitro, abemaciclib causes decreased cellular viability, increased apoptosis, and alterations in autophagy in renal cell carcinoma cell lines. A pre-clinical mouse model of RCC shows abemaciclib in combination with sunitinib to cause dramatic reduction in tumor sizes without overt toxicity. Thus abemaciclib is active in renal cell carcinoma and should be evaluated in a clinical trial in combination with sunitinib. Additionally, CDK4/6 and PIM1 kinase appear to be viable clinical targets in renal cell carcinoma.