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Purpose: Despite promising preclinical studies, toxicities have precluded combinations of chemotherapy and DNA damage response (DDR) inhibitors. We hypothesized that tumor-targeted chemotherapy delivery might enable clinical translation of such combinations., Patients and Methods: In a phase I trial, we combined sacituzumab govitecan, antibody-drug conjugate (ADC) that delivers topoisomerase-1 inhibitor SN-38 to tumors expressing Trop-2, with ataxia telangiectasia and Rad3-related (ATR) inhibitor berzosertib. Twelve patients were enrolled across three dose levels., Results: Treatment was well tolerated, with improved safety over conventional chemotherapy-based combinations, allowing escalation to the highest dose. No dose-limiting toxicities or clinically relevant ≥grade 4 adverse events occurred. Tumor regressions were observed in 2 patients with neuroendocrine prostate cancer, and a patient with small cell lung cancer transformed from EGFR-mutant non-small cell lung cancer., Conclusions: ADC-based delivery of cytotoxic payloads represents a new paradigm to increase efficacy of DDR inhibitors. See related commentary by Berg and Choudhury, p. 3557., (©2023 American Association for Cancer Research.)

The blood-tumor barrier (BTB) limits the entry of effective chemotherapeutic agents into the brain for treatment of malignant tumors like glioblastoma. Poor drug entry across the BTB allows infiltrative glioma stem cells to evade therapy and develop treatment resistance. Regadenoson, an FDA-approved adenosine A2A receptor (A2AR) agonist, has been shown to increase drug delivery across the blood-brain barrier in non-tumor-bearing rodents without a defined mechanism of enhancing BTB permeability. Here, we characterize the time-dependent impact of regadenoson on brain endothelial cell interactions and paracellular transport, using mouse and rat brain endothelial cells and tumor models. In vitro , A2AR activation leads to disorganization of cytoskeletal actin filaments by 30 minutes, downregulation of junctional protein expression by 4 hours, and reestablishment of endothelial cell integrity by 8 hours. In rats bearing intracranial gliomas, regadenoson treatment results in increase of intratumoral temozolomide concentrations, yet no increased survival noted with combined temozolomide therapy. These findings demonstrate regadenoson's ability to induce brain endothelial structural changes among glioma to increase BTB permeability. The use of vasoactive mediators, like regadenoson, which transiently influences paracellular transport, should further be explored to evaluate their potential to enhance central nervous system treatment delivery to aggressive brain tumors. IMPLICATIONS: This study provides insight on the use of a vasoactive agent to increase exposure of the BTB to chemotherapy with intention to improve glioma treatment efficacy., (©2021 The Authors; Published by the American Association for Cancer Research.)

PARP inhibitors are approved for treatment of cancers with BRCA1 or BRCA2 defects. In this study, we prepared and characterized a very long-acting PARP inhibitor. Synthesis of a macromolecular prodrug of talazoparib (TLZ) was achieved by covalent conjugation to a PEG 40kDa carrier via a β-eliminative releasable linker. A single injection of the PEG∼TLZ conjugate was as effective as ∼30 daily oral doses of TLZ in growth suppression of homologous recombination-defective tumors in mouse xenografts. These included the KT-10 Wilms' tumor with a PALB2 mutation, the BRCA1 -deficient MX-1 triple-negative breast cancer, and the BRCA2 -deficient DLD-1 colon cancer; the prodrug did not inhibit an isogenic DLD-1 tumor with wild-type BRCA2 . Although the half-life of PEG∼TLZ and released TLZ in the mouse was only ∼1 day, the exposure of released TLZ from a single safe, effective dose of the prodrug exceeded that of oral TLZ given daily over one month. μPET/CT imaging showed high uptake and prolonged retention of an 89Zr-labeled surrogate of PEG∼TLZ in the MX-1 BRCA1 -deficient tumor. These data suggest that the long-lasting antitumor effect of the prodrug is due to a combination of its long t 1/2 , the high exposure of TLZ released from the prodrug, increased tumor sensitivity upon continued exposure, and tumor accumulation. Using pharmacokinetic parameters of TLZ in humans, we designed a long-acting PEG∼TLZ for humans that may be superior in efficacy to daily oral TLZ and would be useful for treatment of PARP inhibitor-sensitive cancers in which oral medications are not tolerated. SIGNIFICANCE: These findings demonstrate that a single injection of a long-acting prodrug of the PARP inhibitor talazoparib in murine xenografts provides tumor suppression equivalent to a month of daily dosing of talazoparib., (©2020 American Association for Cancer Research.)

Breast cancer metastasis is a leading cause of cancer-related death of women in the United States. A hurdle in advancing metastasis-targeted intervention is the phenotypic heterogeneity between primary and secondary lesions. To identify metastasis-specific gene expression profiles we performed RNA-sequencing of breast cancer mouse models; analyzing metastases from models of various drivers and routes. We contrasted the models and identified common, targetable signatures. Allograft models exhibited more mesenchymal-like gene expression than genetically engineered mouse models (GEMM), and primary culturing of GEMM-derived metastatic tissue induced mesenchymal-like gene expression. In addition, metastasis-specific transcriptomes differed between tail vein and orthotopic injection of the same cell line. Gene expression common to models of spontaneous metastasis included sildenafil response and nicotine degradation pathways. Strikingly, in vivo sildenafil treatment significantly reduced metastasis by 54%, while nicotine significantly increased metastasis by 46%. These data suggest that (i) actionable metastasis-specific pathways can be readily identified, (ii) already available drugs may have great potential to alleviate metastatic incidence, and (iii) metastasis may be influenced greatly by lifestyle choices such as the choice to consume nicotine products. In summary, while mouse models of breast cancer metastasis vary in ways that must not be ignored, there are shared features that can be identified and potentially targeted therapeutically. IMPLICATIONS: The data we present here exposes critical variances between preclinical models of metastatic breast cancer and identifies targetable pathways integral to metastatic spread. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/9/1278/F1.large.jpg., (©2020 American Association for Cancer Research.)

Castration-resistant prostate cancer (CRPC) has greater intratumoral testosterone concentrations than similar tumors from eugonadal men; simple diffusion does not account for this observation. This study was undertaken to ascertain the androgen uptake kinetics, functional, and clinical relevance of de novo expression of the steroid hormone transporter OATP1B3 ( SLCO1B3 ). Experiments testing the cellular uptake of androgens suggest that testosterone is an excellent substrate of OATP1B3 ( K m = 23.2 μmol/L; V max = 321.6 pmol/mg/minute), and cells expressing a doxycycline-inducible SLCO1B3 construct had greater uptake of a clinically relevant concentration of 3H-testosterone (50 nmol/L; 1.6-fold, P = 0.0027). When compared with Slco1b2 (-/-) mice, Slco1b2 (-/-)/ hSLCO1B3 knockins had greater hepatic uptake (15% greater AUC, P = 0.0040) and lower plasma exposure to 3H-testosterone (17% lower AUC, P = 0.0030). Of 82 transporters genes, SLCO1B3 is the second-most differentially expressed transporter in CRPC cell lines (116-fold vs. androgen-sensitive cells), with a differentially spliced cancer-type ct- SLCO1B3 making up the majority of SLCO1B3 expression. Overexpression of SLCO1B3 in androgen-responsive cells results in 1.5- to 2-fold greater testosterone uptake, whereas siRNA knockdown of SLCO1B3 in CRPC cells did not change intracellular testosterone concentration. Primary human prostate tumors express SLCO1B3 to a greater extent than ct-SLCO1B3 (26% of total SLCO1B3 expression vs. 0.08%), suggesting that androgen uptake in these tumor cells also is greater. Non-liver tumors do not differentially express SLCO1B3. Implications: This study suggests that de novo OATP1B3 expression in prostate cancer drives greater androgen uptake and is consistent with previous observations that greater OATP1B3 activity results in the development of androgen deprivation therapy resistance and shorter overall survival. Mol Cancer Res; 15(8); 1096-105. ©2017 AACR ., (©2017 American Association for Cancer Research.)

The role of the insulin-like growth factor (IGF) axis and whether IGFs interact with androgen-suppressing agents in relation to prostate carcinogenesis is unclear. This nested case-control study (n = 1,652 cases/1,543 controls) examined whether serum IGF1, IGF2, IGFBP2, IGFBP3, and the IGF1:IGFBP3 ratio were associated with prostate cancer in the Prostate Cancer Prevention Trial (PCPT), a randomized, placebo-controlled trial of finasteride for prostate cancer prevention. Presence or absence of cancer was determined by prostate biopsy. Baseline serum was assayed for IGF-axis analytes using ELISA. Logistic regression estimated ORs and 95% confidence intervals for risk of total, low-grade (Gleason 2-6) and high-grade (Gleason 7-10) cancers. Results were stratified by intervention assignment. In both the placebo and finasteride arms, serum IGF1, IGF2, IGFBP3, and the IGF1:IGFBP3 ratio were not associated with prostate cancer. However, men in the highest versus lowest quartile of serum IGFBP2 had a 48% (P(trend) = 0.02) and 55% (P(trend) = 0.01) increased risk for total and low-grade cancers, respectively. These IGFBP2 associations were attenuated and no longer statistically significant in the finasteride arm. Our results suggest that in general, serum IGF-axis analytes were not associated with prostate cancer risk in the PCPT in which presence or absence of all cancers was biopsy-determined. The exception was the finding that high serum IGFBP2 is a risk factor for low-grade disease, which was attenuated for men on finasteride. Further research is needed to understand better the risk incurred by high IGFBP2 and whether androgen-suppressing agents such as finasteride influence aspects of IGFBP2 physiology relevant to prostate carcinogenesis.

Background: Finasteride, an inhibitor of 5α-reductase (type II), lowers intraprostatic dihydrotestosterone (DHT), which is reflected in serum as reduced 5α-androstane-3α,17β-diol glucuronide (3α-dG). It also modestly increases serum testosterone (T), estrone (E(1)), and estradiol (E(2)). In this altered hormonal milieu, it is unknown whether serum concentrations of these hormones are associated with prostate cancer risk., Methods: In this nested case-control study of men in the finasteride arm of the Prostate Cancer Prevention Trial, sex steroid hormones and sex hormone binding globulin were measured at baseline and approximately 3-year posttreatment in 553 prostate cancer cases and 694 controls., Results: Median posttreatment changes in concentrations of 3α-dG, T, E(1), and E(2) were -73.8%, +10.1%, +11.2%, and +7.5% (all P < 0.001), respectively. Neither the pre- nor posttreatment concentrations of 3α-dG, nor its change, were associated with risk. Pretreatment, high concentrations of E(1) and low concentrations of T were associated with increased cancer risk [OR; 95% confidence interval (CI) quartile 4 vs. 1: 1.38 (0.99-1.93) P(trend) = 0.03; 0.64 (0.43-0.93) P(trend) = 0.07, respectively]. Posttreatment, high concentrations of both E(1) and E(2) were associated with increased cancer risk [OR; 95% CI quartile 4 vs. 1: 1.54 (1.09-2.17) P(trend) = 0.03; 1.49 (1.07-2.07) P(trend) = 0.02, respectively]., Conclusions: Among finasteride-treated men, concentrations of 3α-dG were not associated with total or Gleason grades 2 to 6, 7 to 10, or 8 to 10 cancer. High serum estrogens may increase cancer risk when intraprostatic DHT is pharmacologically lowered., Impact: Low posttreatment serum estrogens may identify men more likely to benefit from use of finasteride to prevent prostate cancer., (2012 AACR)

Large clinical trials provide a tremendous opportunity to integrate correlative, comprehensive biological studies with invaluable repositories of biospecimens and clinical and other data from the trial. The Prostate Cancer Prevention Trial (PCPT) was a phase III randomized, double-blind, placebo-controlled clinical trial of finasteride in 18,882 men. Clinical data and blood and tissue specimens were collected at baseline and throughout the study, offering an opportunity to create a program project to investigate hypotheses related to the biology underlying the PCPT findings as well as the etiology and risk of prostate cancer. The transition of the randomized PCPT into this translational and epidemiologic scientific investigation required extensive planning and coordination. Five individual but interrelated projects were brought together with the underlying program theme of the genetic, metabolic, and environmental factors associated with the risks of overall and high-grade prostate cancer and how these factors affected the efficacy of finasteride in preventing cancer. All projects with serum-based measures use a single, shared, nested case-control sample of participants so that each subject provides a more complete biomarker and genetic profile for the evaluation of joint effects of these factors. Strengths of this program include the following: 1) the control group contains only men who are negative for biopsy-detected cancer, 2) the statistical methods to evaluate associations of risk factors with disease are shared across all projects, 3) the large number of cancer cases with fully characterized genetic, metabolic, and behavioral exposures, 4) a central pathology core histopathologically classified the prostate cancer, and 5) cancer cases identified during the PCPT reflect the characteristics of cases currently being detected in the prostate-specific antigen screening era, leading to contemporary and highly relevant results. This article describes the comprehensive methodology and multidisciplinary collaborations, both national and international, essential to a major risk-modeling research program. We provide a framework for doing collaborative research in an international setting structured around a common theme of a clinical trial., (©2010 AACR.)

Background: Several prospective studies suggest that use of cholesterol-lowering statin drugs is inversely associated with advanced stage and possibly high-grade prostate cancer. One study reported that men with low cholesterol had a lower risk of high-grade prostate cancer. Given these findings, we investigated the association between low serum cholesterol and prostate cancer risk in the Prostate Cancer Prevention Trial., Methods: We conducted a cohort study of 5,586 men ages >or=55 years who were randomized to the placebo arm of the Prostate Cancer Prevention Trial between 1993 and 1996. Serum cholesterol was measured enzymatically at entry. By the end of follow-up, 1,251 prostate cancer cases were confirmed. We used logistic regression to calculate the multivariable odds ratio (OR) of total, and Gleason 2 to 6 (n = 993), 7 (n = 199), and 8 to 10 (n = 59) prostate cancer comparing low serum (normal, <200 mg/dL) to high-serum (borderline and elevated cholesterol, >or=200 mg/dL) cholesterol., Results: Men with low cholesterol had a lower risk of Gleason 8 to 10 prostate cancer [OR, 0.41; 95% confidence interval (CI), 0.22-0.77] than men with high cholesterol. No association was present for prostate cancer overall (OR, 0.97; 95% CI, 0.85-1.11), Gleason 2 to 6 disease (OR, 1.03; 95% CI, 0.89-1.18), or Gleason 7 disease (OR, 0.93; 95% CI, 0.69-1.24)., Conclusion: These prospective results support that men with low cholesterol have a reduced risk of high-grade prostate cancer. These and other contemporary data that suggest that cholesterol metabolism should be investigated further in the etiology of prostate cancer.

Human bone stromal cells, after three-dimensional coculture with human prostate cancer (PCa) cells in vitro, underwent permanent cytogenetic and gene expression changes with reactive oxygen species serving as mediators. The evolved stromal cells are highly inductive of human PCa growth in mice, and expressed increased levels of extracellular matrix (versican and tenascin) and chemokine (BDFN, CCL5, CXCL5, and CXCL16) genes. These genes were validated in clinical tissue and/or serum specimens and could be the predictors for invasive and bone metastatic PCa. These results, combined with our previous observations, support the concept of permanent genetic and behavioral changes of PCa epithelial cells after being either cocultured with prostate or bone stromal cells as three-dimensional prostate organoids or grown as tumor xenografts in mice. These observations collectively suggest coevolution of cancer and stromal cells occurred under three-dimensional growth condition, which ultimately accelerates cancer growth and metastasis.

Several of the hormone-mediated cancers (breast, endometrial, ovarian, and prostate) represent major cancers in both incidence and mortality rates. The etiology of these cancers is in large part modulated by the hormones estrogen and testosterone. As advanced disease develops, the common treatment for these cancers is chemotherapy. Thus, genes that can alter tissue response to hormones and alter clinical response to chemotherapy are of major interest. The cytochrome P450 1B1 (CYP1B1) may be involved in disease progression and modulate the treatment in the above hormone-mediated cancers. This review will focus on the pharmacogenetics of CYP1B1 in relation to hormone-mediated cancers and provide an assessment of cancer risk based on CYP1B1 polymorphisms and expression. In addition, it will provide a summary of CYP1B1 gene regulation and expression in normal and neoplastic tissue.

Paclitaxel (Taxol) and docetaxel (Taxotere) have been shown to inhibit angiogenesis at low concentrations that do not affect cancer cell proliferation. Here, we used rat aortic rings and human umbilical vein endothelial cells to evaluate the influence of their formulation vehicles Cremophor EL and polysorbate 80, as well as serum binding proteins on taxane-mediated antiangiogenesis. The data show that clinically relevant concentrations of the vehicles and binding proteins nullify the antiangiogenic activity of both taxanes. It is suggested that these agents may need to be used at much higher doses than anticipated for effective antiangiogenic chemotherapy.

Inhibition of angiogenesis is currently perceived as one of the promising strategies in the treatment of cancer. The antiangiogenic property of thalidomide has inspired a second wave of research on this teratogenic drug. Previous studies from our group and others demonstrated that metabolites of thalidomide are responsible for the drug's pharmacological actions. On the basis of the structures of these metabolites, we synthesized 118 thalidomide analogues. Preliminary screening selected 7 of these 118 analogues for more extensive testing in the current study. In the rat aortic ring assay, all 4 analogues in the N-substituted class and 2 of the 3 analogues in the tetrafluorinated class significantly inhibited microvessel outgrowth at 12.5-200 microM. Thalidomide failed to block angiogenesis at similar concentrations. Subsequently, the effects of these analogues on human umbilical vein endothelial cell proliferation and tube formation were determined. Those analogues showing antiangiogenicity in the rat aortic ring assay also demonstrated antiproliferative action in human umbilical vein endothelial cells. Cell proliferation was not affected by thalidomide. Interestingly, all 7 analogues as well as thalidomide suppressed tube formation. Two tetrafluorinated analogues consistently showed the highest potency and efficacy in all three assays. The in vivo toxicity of representative analogues from each class was also evaluated. Taken together, our results support the further development and evaluation of novel thalidomide analogues as antiangiogenic agents.

Hypoxia limits tumor growth but selects for higher metastatic potential. We tested the functional activity of hypoxia-inducible factor-1 (HIF-1) in prostate cell lines ranging from normal epithelial cells (PrEC), hormone-dependent LNCaP, hormone-independent DU145, PC-3 to highly metastatic PC-3M cancer cell lines. We found that HIF-1-stimulated transcription was the lowest in PrEC and LNCaP cells and the highest in PC-3M cells. The induction by hypoxia of the HIF-1 dependent genes Cap43 and GAPDH was the highest in the most aggressive PC-3M cancer cells. Because these advanced prostate cancer cell lines have lost p53 function, this further shifts a balance from p53 to HIF-1 transcriptional regulation, and a high ratio of HIF-1-dependent:p53-dependent transcription was a marker of the advanced malignant phenotype. Transient transfection of HIF-1alpha expression vector induced transcription from p21 promoter construct in prostate cancer cell lines. Furthermore, hypoxia slightly induced p21 mRNA in these cells. However, neither expression of p21 nor hypoxia caused growth arrest in PC-3M cells. Therefore, high inducibility of HIF-1-dependent genes, loss of p53 functions with high ratio of HIF-1-dependent:p53-dependent transcription, and loss of sensitivity to p21 inhibition is a part of hypoxic phenotype associated with aggressive cancer behavior.

The pharmacokinetics of UCN-01 after administration as a 72- or 3-h infusion to cancer patients in initial Phase I trials displayed distinctive features that could not have been predicted from preclinical data. The distribution volumes (0.0796-0.158 liters/kg) and the systemic clearance (0.0407-0.252 ml/h/kg) were extremely low, in contrast to large distribution volume and rapid systemic clearance in experimental animals. The elimination half-lives (253-1660 h) were unusually long. In vitro protein binding experiments demonstrated that UCN-01 was strongly bound to human alpha1-acid glycoprotein. The results suggest that unusual pharmacokinetics of UCN-01 in humans could be due, at least in part, to its specifically high binding to alpha1-acid glycoprotein.

Carboxyamido-triazole (CAI) is a synthetic inhibitor of non-excitable calcium channels that reversibly inhibits angiogenesis, tumor cell proliferation, and metastatic potential. Inhibition of calcium influx and calcium-dependent events is a potential common mechanism underlying these effects of CAI. The cytostatic and antiangiogenic properties of CAI led to its development for clinical investigation. In a Phase I clinical trial open to patients with refractory solid tumors, 49 patients received p.o. administered CAI daily or every other day. Two oral formulations, PEG-400 CAI solution and a gelatin capsule containing CAI in PEG-400, were tested. All administered dosages of CAI yielded plasma concentration at or above the range demonstrated to be effective in inhibiting signaling and cancer progression in vitro and in preclinical models (1 microgram/ml, 2.3 microM). Toxicity of p.o. administered CAI most commonly consisted of dose-related grade 1-2 nausea, vomiting, and occasional anorexia. CAI administration at bedtime ameliorated gastrointestinal complaints in many patients; others required addition of simple antiemetic regimens, usually consisting of metoclopropamide or prochlorperazine. Gastrointestinal complaints were the cause for compliance-limiting toxicity at 175 mg/m2/day of the liquid formulation and 125 mg/m2/day of the gelatin capsule formation. Reversible and rare sensory axonal neuropathy (grade 3, 1 patient) and neutropenia (grade 4, 1 patient) were dose-limiting toxicities observed at the 330 mg/m2 every-other-day liquid CAI dose level. No evidence of cumulative end organ damage or central nervous system injury was observed. Disease stabilization and improvement in performance status was observed. Disease stabilization and improvement in performance status was observed in 49% of evaluable patients who had disease progression before CAI. Disease stabilization and associated improvement in performance status was seen in patients with renal cell carcinoma (7 months), pancreaticobiliary carcinomas (3, 5, and 5 months), melanoma (7 months), ovarian cancer (7 months), and non-small cell lung cancer (3 months). The recommended Phase II doses from this trial are 150 mg/m2/day in the liquid formation and 100 mg/m2/day in the gelatin capsule formation.

Phenylacetate has recently been shown to suppress tumor growth and promote differentiation in experimental models. A phase I trial of phenylacetate was conducted in 17 patients with advanced solid tumors. Each patient received a single i.v. bolus dose followed by a 14-day continuous i.v. infusion of the drug. Twenty-one cycles of therapy were administered at four dose levels, achieved by increasing the rate of the continuous i.v. infusion. Phenylacetate displayed nonlinear pharmacokinetics [Km = 105.1 +/- 44.5 (SD) microgram/ml, Vmax = 24.1 +/- 5.2 mg/kg/h and Vd = 19.2 +/- 3.3 L]. There was also evidence for induction of drug clearance. Ninety-nine % of phenylacetate elimination was accounted for by conversion to phenylacetylglutamine, which was excreted in the urine. Continuous i.v. infusion rates resulting in serum phenylacetate concentrations exceeding Km often resulted in rapid drug accumulation and dose-limiting toxicity, which consisted of reversible central nervous system depression, preceded by emesis. Three of nine patients with metastatic, hormone-refractory prostate cancer maintained stable prostatic specific antigen levels for more than 2 months; another had less bone pain. One of six patients with glioblastoma multiforme, whose steroid dosage has remained unchanged for the duration of therapy, has sustained functional improvement for more than 9 months. The use of adaptive control with feedback for the dosing of each patient enabled us to safely maintain stable phenylacetate concentrations up to the range of 200-300 micrograms/ml, which resulted in clinical improvement in some patients with advanced disease.