Association of plasma NRP2 and VEGF-C levels with prostate cancer disease severity.

BACKGROUND: Neuropilin 2 (NRP2) expression in tissue is an independent prognostic factor for aggressive prostate cancer. Since the NRP2 pathway activation is thought to occur in part through secondary resistance, quantification of NRP2 in initial tissue biopsy specimens collected at diagnosis may have limited utility in identifying patients at highest risk for morbidity and mortality. Given that metastatic tissue is only occasionally obtained for analysis, there is a need for development of a plasma biomarker indicative of NRP2 pathway activation to potentially inform prostate cancer prognosis. Therefore, we investigated if plasma levels of NRP2 or vascular endothelial growth factor C (VEGF-C), a known soluble ligand of NRP2, are prognostic for prostate cancer. We hypothesized that plasma NRP2 and VEGF-C would be associated with more advanced disease or relapsed disease. METHODS: NRP2 and VEGF-C levels were quantified by enzyme-linked immunoassay in plasma samples obtained from 145 prostate cancer patients in an opportunistic biobank. These patients were either (1) newly diagnosed (N = 28), (2) in remission (N = 56), or (3) relapsed disease (N = 61). Plasma samples from 15 adult males without known malignancy served as a comparator cohort. Statistical analysis was performed to investigate the association of plasma NRP2/VEGF-C with patient outcomes, adjusting for age, race, prostate-specific antigen (PSA), Gleason score, and tumor stage at diagnosis. RESULTS: Neither NRP2 nor VEGF-C levels were significantly different in cancer patients compared to noncancer controls. We observed no clear association between plasma NRP2 and disease severity. Increased plasma VEGF-C was significantly associated with disease remission and correlated with Stage I/II and intermediate-risk Gleason score. Neither NRP2 nor VEGF-C correlated with PSA level. CONCLUSIONS: Although tissue NRP2 expression correlates with severe disease, this was not observed for plasma NRP2. Plasma NRP2 levels did not correlate with disease severity or relapse. VEGF-C was highest in patients in remission and with less severe disease. Future investigation is needed to identify noninvasive methods to assess tumor NRP2 status.

NCCN Guidelines® Insights: Prostate Cancer, Version 3.2024.

The NCCN Guidelines for Prostate Cancer include recommendations for staging and risk assessment after a prostate cancer diagnosis and for the care of patients with localized, regional, recurrent, and metastatic disease. These NCCN Guidelines Insights summarize the panel's discussions for the 2024 update to the guidelines with regard to initial risk stratification, initial management of very-low-risk disease, and the treatment of nonmetastatic recurrence.

A case of metastatic adenoid cystic (basal cell) carcinoma of the prostate: Systemic therapy for a rare disease.

BACKGROUND: Metastatic adenoid cystic (basal cell) carcinoma of the prostate is an exceedingly rare disease entity. As a result, no current consensus exists for optimal systemic therapy. METHODS: We present a patient with metastatic adenoid cystic (basal cell) carcinoma of the prostate who subsequently received systemic treatment, including chemotherapy and immunotherapy. We comprehensively reviewed all published data on therapy outcomes in advanced disease. RESULTS: Our patient benefited from combination chemotherapy (carboplatin and paclitaxel), with objective radiographic response and reduction in cancer-related pain. However, chemotherapy was stopped due to cumulative neurotoxicity, and subsequent immunotherapy with atezolizumab did not produce any response. Our literature review revealed inconsistent outcomes with various treatments but showed most promise with chemotherapy. Targeted therapy and immunotherapy seem to benefit specific cases, and androgen deprivation therapy had minimal evidence of benefit. CONCLUSION: Based on the findings of our case report and literature review, we suggest platinum-based chemotherapy doublets as first-line treatment for metastatic cases of adenoid cystic (basal cell) carcinoma of the prostate, reserving targeted therapy or immunotherapy for select cases based upon molecular profiles.

Prostate Cancer, Version 4.2023, NCCN Clinical Practice Guidelines in Oncology.

The NCCN Guidelines for Prostate Cancer provide a framework on which to base decisions regarding the workup of patients with prostate cancer, risk stratification and management of localized disease, post-treatment monitoring, and treatment of recurrence and advanced disease. The Guidelines sections included in this article focus on the management of metastatic castration-sensitive disease, nonmetastatic castration-resistant prostate cancer (CRPC), and metastatic CRPC (mCRPC). Androgen deprivation therapy (ADT) with treatment intensification is strongly recommended for patients with metastatic castration-sensitive prostate cancer. For patients with nonmetastatic CRPC, ADT is continued with or without the addition of certain secondary hormone therapies depending on prostate-specific antigen doubling time. In the mCRPC setting, ADT is continued with the sequential addition of certain secondary hormone therapies, chemotherapies, immunotherapies, radiopharmaceuticals, and/or targeted therapies. The NCCN Prostate Cancer Panel emphasizes a shared decision-making approach in all disease settings based on patient preferences, prior treatment exposures, the presence or absence of visceral disease, symptoms, and potential side effects.

NCCN Guidelines® Insights: Prostate Cancer, Version 1.2023.

The NCCN Guidelines for Prostate Cancer address staging and risk assessment after a prostate cancer diagnosis and include management options for localized, regional, recurrent, and metastatic disease. The NCCN Prostate Cancer Panel meets annually to reevaluate and update their recommendations based on new clinical data and input from within NCCN Member Institutions and from external entities. These NCCN Guidelines Insights summarizes much of the panel's discussions for the 4.2022 and 1.2023 updates to the guidelines regarding systemic therapy for metastatic prostate cancer.

Impact of Proton Pump Inhibitor Use on the Effectiveness of Immune Checkpoint Inhibitors in Advanced Cancer Patients.

BACKGROUND: The gut microbiome plays a critical role in modulating the therapeutic effect of immune checkpoint inhibitors (ICIs). Proton pump inhibitors (PPIs) are commonly used in cancer patients and may affect the gut microbiome by altering gut pH. OBJECTIVE: To evaluate if concurrent use of PPI is associated with overall survival (OS) and progression-free survival (PFS) in patients with stage IV non-small-cell lung cancer (NSCLC), melanoma, renal cell carcinoma, transitional cell carcinoma, or head and neck squamous cell carcinoma. METHODS: This was a single-center retrospective cohort study of advanced cancer adult patients who received nivolumab or pembrolizumab between September 1, 2014, and August 31, 2019. Concomitant PPI exposure was defined as PPI use 0 to 30 days before or after initiation of ICIs. Treatment outcome was OS and PFS. RESULTS: A total of 233 patients were included in our study. Concomitant PPI use was not significantly associated with OS (hazard ratio [HR] = 1.22; 95% CI = 0.80-1.86) or PFS (HR = 1.05; 95% CI = 0.76-1.45) in patients with ICI use. The effect estimates were robust after adjusting for covariates in multivariate analysis and in patients with NSCLC. CONCLUSION AND RELEVANCE: Concomitant PPI use was not associated with the effectiveness of nivolumab or pembrolizumab. Certain predictors of survival outcomes related to PPI use in patients receiving immunotherapy, such as the time window and indication of PPI exposure and autoimmune disorders, should be explored in the future to better carve out the impact of PPI on the effectiveness of ICI use.

NCCN Guidelines Insights: Prostate Cancer, Version 1.2021.

The NCCN Guidelines for Prostate Cancer address staging and risk assessment after a prostate cancer diagnosis and include management options for localized, regional, and metastatic disease. Recommendations for disease monitoring and treatment of recurrent disease are also included. The NCCN Prostate Cancer Panel meets annually to reevaluate and update their recommendations based on new clinical data and input from within NCCN Member Institutions and from external entities. This article summarizes the panel's discussions for the 2021 update of the guidelines with regard to systemic therapy for metastatic castration-resistant prostate cancer.

Current Management of Refractory Germ Cell Tumors.

PURPOSE OF REVIEW: Germ cell tumors (GCTs) are the most common solid tumors affecting men between ages of 20 and 34 years. Most of the cases, even in advanced disease, will have good prognosis. However, around 20-30% of advanced disease will be refractory or develop relapse after treatment. Herein, we review the current management of refractory/relapsed GCTs. RECENT FINDINGS: Salvage treatment of GCTs has been a controversial topic for the last few decades. Conventional dose chemotherapy (CDCT), high-dose chemotherapy (HDCT) with stem cell infusion, and surgical salvage were proven to be effective and curative options in some cases. The international randomized trial (TIGER) will ultimately answer which chemotherapy approach may be optimal. Furthermore, the usage of immunotherapy is still under investigation with limited data so far in the setting of relapsed/refractory GCTs. Curative paradigms including with CDCT and HDCT are possible, although novel approaches beyond HDCT are still needed to eliminate mortality from this disease.

Risk of development of visceral metastases subsequent to abiraterone vs placebo: An analysis of mode of radiographic progression in COU-AA-302.

BACKGROUND: Abiraterone increases survival in prostate cancer, but tumors resistant to abiraterone can exhibit a hormonally resistant, aggressive phenotype. We hypothesized that the therapeutic pressure of abiraterone is resulting in more clinically aggressive disease at progression, characterized by increased visceral metastases. Our objective was to determine whether abiraterone increased the risk of development of visceral metastases at the time of progression compared with placebo in a randomized phase III trial. METHODS: We performed a post hoc analysis of the COU-AA-302 trial of abiraterone plus prednisone vs placebo plus prednisone in patients with metastatic castration-resistant prostate cancer. The primary outcome was the development of visceral metastases. The cumulative incidences of visceral metastases were calculated by the Kaplan-Meier method and compared using log-rank testing. Multivariable Cox regression analysis assessed for the independent association of abiraterone with the development of visceral metastases. RESULTS: Eighty-four of 1088 patients developed visceral metastases during study. Log-rank testing and Cox regression showed no difference in time to visceral metastases between groups (HR 1.01 [95% confidence interval (CI), 0.65-1.56]; P = .97). Abiraterone treatment was not associated with the development of visceral metastases in multivariable analysis (HR 0.89 [95% CI, 0.57-1.40]; P = .62). The study was limited by censoring of radiographic outcomes at the time of completion of primary study therapy; longer term risks were not assessed. CONCLUSIONS: Abiraterone was not associated with increased risk of visceral metastatic disease at the time of progression compared with placebo.

Bipolar androgen therapy in men with metastatic castration-resistant prostate cancer after progression on enzalutamide: an open-label, phase 2, multicohort study.

BACKGROUND: Prostate cancer that progresses after enzalutamide treatment is poorly responsive to further antiandrogen therapy, and paradoxically, rapid cycling between high and low serum testosterone concentrations (bipolar androgen therapy [BAT]) in this setting might induce tumour responses. We aimed to evaluate BAT in patients with metastatic castration-resistant prostate cancer that progressed after enzalutamide. METHODS: We did this single-centre, open-label, phase 2, multicohort study in the USA. We included patients aged 18 years or older who had histologically confirmed and radiographically documented metastatic castration-resistant prostate cancer, with no more than two previous second-line hormonal therapies, and a castrate concentration of testosterone. Patients were asymptomatic, with Eastern Cooperative Oncology Group performance status of 0-2, and did not have high-risk lesions for tumour flare (eg, >5 sites of visceral disease or bone lesions with impending fracture). For the cohort reported here, we required patients to have had progression on enzalutamide with a continued prostate-specific antigen (PSA) rise after enzalutamide treatment discontinuation. Patients received BAT, which consisted of intramuscular testosterone cipionate 400 mg every 28 days until progression and continued luteinising hormone-releasing hormone agonist therapy. Upon progression after BAT, men were rechallenged with oral enzalutamide 160 mg daily. The co-primary endpoints were investigator-assessed 50% decline in PSA concentration from baseline (PSA50) for BAT (for all patients who received at least one dose) and for enzalutamide rechallenge (based on intention-to-treat analysis). These data represent the final analysis for the post-enzalutamide cohort, while two additional cohorts (post-abiraterone and newly castration-resistant prostate cancer) are ongoing. The trial is registered with ClinicalTrials.gov, number NCT02090114. FINDINGS: Between Aug 28, 2014, and May 18, 2016, we accrued 30 eligible patients and treated them with BAT. Nine (30%; 95% CI 15-49; p<0·0001) of 30 patients achieved a PSA50 to BAT. 29 patients completed BAT and 21 proceeded to enzalutamide rechallenge, of whom 15 (52%; 95% CI 33-71; p<0·0001) achieved a PSA50 response. During BAT, the only grade 3-4 adverse event occurring in more than one patient was hypertension (three [10%] patients). Other grade 3 or worse adverse events occurring during BAT in one [3%] patient each were pulmonary embolism, myocardial infarction, urinary obstruction, gallstone, and sepsis. During enzalutamide retreatment, no grade 3-4 toxicities occurred in more than one patient. No treatment-related deaths were reported during either BAT or enzalutamide retreatment. INTERPRETATION: BAT is a safe therapy that resulted in responses in asymptomatic men with metastatic castration-resistant prostate cancer and also resensitisation to enzalutamide in most patients undergoing rechallenge. Further studies with BAT are needed to define the potential clinical role for BAT in the management of metastatic castration-resistant prostate cancer and the optimal strategy for sequencing between androgen and antiandrogen therapies in metastatic castration-resistant prostate cancer to maximise therapeutic benefit to patients. FUNDING: National Institutes of Health and National Cancer Institute.

Chemotherapy options in castration-resistant prostate cancer.

INTRODUCTION: The treatment landscape for patients with metastatic castration-resistant prostate cancer (CRPC) is evolving, with recent approvals of immune therapy, novel hormonal therapy, and bone-targeted therapy. Chemotherapy remains an essential component of the armamentarium. Herein, we review current chemotherapy options for patients with CRPC and discuss future challenges. METHODS: We reviewed literature for chemotherapy agents in prostate cancer, with special attention to the evidence for efficacy of the currently approved agents. We also reviewed emerging data on biomarkers of response to chemotherapy for CRPC. RESULTS: Taxanes, especially docetaxel and cabazitaxel, have first- and second-line indications for CRPC, respectively, with both providing a survival benefit. Multiple attempts to improve on the single agent efficacy of docetaxel with combination therapy have not generally been successful although platinum combinations are used for resistant phenotypes. Reductions in prostate-specific antigen by ≥30% and reductions in circulating tumor cells (CTCs) to ≤ 5 are associated with improved survival on chemotherapy. Chemotherapy may continue to be effective therapy for patients with biomarkers that are associated with resistance to androgen-directed therapies (androgen receptor splice variant 7 positivity in CTCs or high CTC heterogeneity). CONCLUSIONS: Chemotherapy remains an essential component of CRPC therapy, and biomarkers are being identified to define clinical scenarios where chemotherapy may be the optimal therapy choice.

Identification and management of toxicities from immune checkpoint-blocking drugs.

Immune checkpoint-blocking drugs such as ipilimumab, pembrolizumab, and nivolumab have demonstrated clinical efficacy as anticancer agents. Through modulation of immunoregulatory molecules, these novel therapeutics can produce durable cancer remissions in a variety of tumor types. As these medications are administered to an increasing number of patients, clinicians must be able to recognize and treat the associated immune-related side effects. This review summarizes the unique mechanisms of toxicity associated with immune checkpoint-blocking drugs, appropriate steps in patient evaluation, and strategies for mitigating risk and optimizing patient outcomes. Although the management of each patient receiving immune checkpoint-blockade therapy must be individualized, a conceptual framework upon which to base a multidisciplinary approach to best practices will help oncology practitioners deliver safe and effective care.

Diagnosis of Metastatic Non-Small Cell Lung Cancer during Hospitalization: Missed Opportunity for Optimal Supportive Care?

PURPOSE: The usual workup for patients newly diagnosed with advanced non-small cell lung cancer (NSCLC) occurs in the ambulatory setting. A subset of patients present with acute care needs and receive the diagnosis while hospitalized. Palliative therapies are typically initiated when patients are outpatients, even when diagnoses are made when they are inpatients. Lengthy admission, rehabilitation needs after discharge, and readmissions are possible barriers to timely and adequate outpatient follow-up. The outcomes for these patients diagnosed in the hospital are not well characterized. We hypothesized that patients have been ill-served by current treatment patterns, as reflected by low rates of cancer-directed treatment and poor survival. PATIENTS AND METHODS: We performed a retrospective study of new inpatient diagnoses of metastatic NSCLC at our institution between 1 January 2012 and 1 January 2022. The primary outcome was the proportion of patients ultimately receiving cancer-directed therapy. Other outcomes included time to treatment, use of targeted therapy, palliative care/hospice utilization, and overall survival (OS). RESULTS: Seventy-three patients were included, with a median age of 57 years. Twenty-seven patients (37%) ultimately received systemic therapy with a median time from diagnosis to treatment of 37.5 days. Overall, 5.4% patients died while admitted, 6.8% were discharged to a hospice, 21.9% were discharged to a facility, and 61.6% were discharged home. Only 20 patients (27%) received palliative care consultation. The median OS for our entire population was 2.3 months, with estimated 6-month and 1-year OS rates of 32% and 22%, respectively. CONCLUSION: Patients with new inpatient diagnoses of metastatic NSCLC have extremely poor outcomes. Current management strategies resulted in few patients starting systemic therapy, yet most of the patients did not receive palliative care or hospice involvement. These findings demonstrate that there is a high unmet need to optimally support and palliate these patients.

Comparison of sequential versus concurrent chemoradiation regimens in non-metastatic muscle-invasive bladder cancer.

PURPOSE: The treatment approach for non-metastatic bladder cancer is guided by an invasion of the muscular layer of the bladder wall. Radical cystectomy is the recommended treatment for muscle-invasive disease. However, it has considerable morbidity and mortality and is not suited for many patients. Trimodality therapy consisting of chemoradiation after transurethral resection of bladder tumor offers a definitive approach with bladder-sparing potential. However, there is a lack of research defining the optimal combination of chemotherapy and radiation in this setting. MATERIALS AND METHODS: We extracted patient data from the National Cancer Database to compare survival outcomes and demographic factors in 2,227 non-metastatic bladder cancer patients who were treated with chemotherapy sequential to or concurrently with radiation. Sequential treatment was defined as chemotherapy beginning >14 days before radiation, and concurrent was defined as beginning within 14 days of the first radiation. RESULTS: The sequential treatment group patients were younger (mean age, 74 vs. 78 years; p < 0.001) with more advanced disease. We found no difference in overall survival between patients who received chemotherapy sequential to radiation and those who received concurrent chemoradiation only (p = 0.533). CONCLUSION: Our data are concordant with a previous prospective study, and support that chemotherapy prior to radiation does not decrease survival outcomes relative to patients receiving only concurrent chemoradiation. Given that the sequential group had an overall higher stage but no difference in survival, downstaging chemotherapy prior to radiation may be helpful in these patients. Further studies including a larger, multi-institutional clinical trial are indicated to support clinical decision-making.

Androgen receptor inhibition suppresses anti-tumor neutrophil response against bone metastatic prostate cancer via regulation of TßRI expression.

Bone metastatic disease of prostate cancer (PCa) is incurable and progression in bone is largely dictated by tumor-stromal interactions in the bone microenvironment. We showed previously that bone neutrophils initially inhibit bone metastatic PCa growth yet metastatic PCa becomes resistant to neutrophil response. Further, neutrophils isolated from tumor-bone lost their ability to suppress tumor growth through unknown mechanisms. With this study, our goal was to define the impact of metastatic PCa on neutrophil function throughout tumor progression and to determine the potential of neutrophils as predictive biomarkers of metastatic disease. Using patient peripheral blood polymorphonuclear neutrophils (PMNs), we identified that PCa progression dictates PMN cell surface markers and gene expression, but not cytotoxicity against PCa. Importantly, we also identified a novel phenomenon in which second generation androgen deprivation therapy (ADT) suppresses PMN cytotoxicity via increased transforming growth factor beta receptor I (TßRI). High dose testosterone and genetic or pharmacologic TßRI inhibition rescued androgen receptor-mediated neutrophil suppression and restored neutrophil anti-tumor immune response. These studies highlight the ability to leverage standard-care ADT to generate neutrophil anti-tumor responses against bone metastatic PCa.

The evolving landscape of PARP inhibitors in castration-resistant prostate cancer: a spotlight on treatment combinations.

INTRODUCTION: PARP inhibition in prostate cancer has become a standard-of-care option for men with metastatic castration-resistant prostate cancer (mCRPC) with deficiency in homologous recombination repair (HRRd). The benefit varies based upon the characteristics of the PARP inhibitor used and the underlying HRR defect. Optimal patient selection remains a clinical challenge, and investigations are underway to identify effective combination therapies to expand the population that benefits. AREAS COVERED: We review the clinical development of the FDA-approved PARP inhibitors olaparib and rucaparib. Additionally, we explore the status of other PARP inhibitors that remain experimental in prostate cancer, based upon review of published abstracts, articles, and clinicaltrials.gov. Most new studies, including phase 3 trials for talazoparib and rucaparib, involve combinations with novel androgen receptor signaling inhibitors. We review the landscape of emerging PARP inhibitor-based combination therapies. EXPERT OPINION: For men with BRCA1 or BRCA2 mutations, olaparib has a clear role for early use in the disease course of mCRPC. For men with other HRR mutations, that benefit remains less well defined, particularly with the availability of other treatment choices. Ultimately, combination strategies are likely to be the best avenue for men without BRCA1 or BRCA2 mutations to be treated with PARP inhibition.

Impact of Performance Status on Response and Survival Among Patients Receiving Checkpoint Inhibitors for Advanced Solid Tumors.

PURPOSE: Clinical trials, which led to the approval of immune checkpoint inhibitors (ICI), have been almost exclusively performed in patients with good Eastern Cooperative Oncology Group performance status (ECOG PS of 0-1). However, ICI remains an attractive option for patients with advanced tumors and poor PS. We hypothesized that patients with ECOG PS ≥ 2 would have worse outcomes with ICI. METHODS: We retrospectively identified patients with advanced solid tumors who were treated with ICI at our institution. The log-rank test compared the survival among patients with different ECOG PS. We used a proportional hazards model to assess association between ECOG PS and overall survival (OS) with adjustment for covariates including age, sex, malignancy type, time from advance disease diagnosis, and line of therapy. We compared overall response rates between groups with Pearson chi-square exact test. We also analyzed in-hospital mortality and hospice referral rates. RESULTS: We identified 257 patients treated with ICI. One hundred eighty-two patients had ECOG PS 0-1, and 75 had ECOG PS ≥ 2. The median overall survival was 12.6 months for the ECOG PS 0-1 group compared with 3.1 months for the ECOG PS ≥ 2 group (P < .001). The overall response rate for patients with ECOG PS 0-1 was 23% compared with 8% for those with poor PS (P = .005). Patients with poor PS treated with ICI had similar hospice referral rates (67% for ECOG PS ≥ 2 v 61.9% for ECOG PS 0-1, P = .50) but were more likely to have in-hospital death as compared with the good PS group (28.6% v 15.1%, P = .035). CONCLUSION: Despite the appeal of ICI in patients with advanced malignancy and poor PS, outcomes in this cohort were poor. Prospective trials defining the activity and role of ICI in poor PS are urgently needed.

Neuropilin-2 axis in regulating secretory phenotype of neuroendocrine-like prostate cancer cells and its implication in therapy resistance.

Neuroendocrine (NE)-like tumors secrete various signaling molecules to establish paracrine communication within the tumor milieu and to create a therapy-resistant environment. It is important to identify molecular mediators that regulate this secretory phenotype in NE-like cancer. The current study highlights the importance of a cell surface molecule, Neuropilin-2 (NRP2), for the secretory function of NE-like prostate cancer (PCa). Our analysis on different patient cohorts suggests that NRP2 is high in NE-like PCa. We have developed cell line models to investigate NRP2's role in NE-like PCa. Our bioinformatics, mass spectrometry, cytokine array, and other supporting experiments reveal that NRP2 regulates robust secretory phenotype in NE-like PCa and controls the secretion of factors promoting cancer cell survival. Depletion of NRP2 reduces the secretion of these factors and makes resistant cancer cells sensitive to chemotherapy in vitro and in vivo. Therefore, targeting NRP2 can revert cellular secretion and sensitize PCa cells toward therapy.

Precise engineering of targeted nanoparticles by using self-assembled biointegrated block copolymers.

There has been progressively heightened interest in the development of targeted nanoparticles (NPs) for differential delivery and controlled release of drugs. Despite nearly three decades of research, approaches to reproducibly formulate targeted NPs with the optimal biophysicochemical properties have remained elusive. A central challenge has been defining the optimal interplay of parameters that confer molecular targeting, immune evasion, and drug release to overcome the physiological barriers in vivo. Here, we report a strategy for narrowly changing the biophysicochemical properties of NPs in a reproducible manner, thereby enabling systematic screening of optimally formulated drug-encapsulated targeted NPs. NPs were formulated by the self-assembly of an amphiphilic triblock copolymer composed of end-to-end linkage of poly(lactic-co-glycolic-acid) (PLGA), polyethyleneglycol (PEG), and the A10 aptamer (Apt), which binds to the prostate-specific membrane antigen (PSMA) on the surface of prostate cancer (PCa) cells, enabling, respectively, controlled drug release, "stealth" properties for immune evasion, and cell-specific targeting. Fine-tuning of NP size and drug release kinetics was further accomplished by controlling the copolymer composition. By using distinct ratios of PLGA-b-PEG-b-Apt triblock copolymer with PLGA-b-PEG diblock copolymer lacking the A10 Apt, we developed a series of targeted NPs with increasing Apt densities that inversely affected the amount of PEG exposure on NP surface and identified the narrow range of Apt density when the NPs were maximally targeted and maximally stealth, resulting in most efficient PCa cell uptake in vitro and in vivo. This approach may contribute to further development of targeted NPs as highly selective and effective therapeutic modalities.

Biomarkers for Treatment Response in Advanced Prostate Cancer.

Multiple treatment options with different mechanisms of action are currently available for the management of metastatic prostate cancer. However, the optimal use of these therapies-specifically, the sequencing of therapies-is not well defined. In order to obtain the best clinical outcomes, patients need to be treated with the therapies that are most likely to provide benefit and avoid toxic therapies that are unlikely to be effective. Ideally, predictive biomarkers that allow for the selection of the therapies most likely to be of benefit would be employed for each treatment decision. In practice, biomarkers including tumor molecular sequencing, circulating tumor DNA, circulating tumor cell enumeration and androgen receptor characteristics, and tumor cell surface expression (PSMA), all may have a role in therapy selection. In this review, we define the established prognostic and predictive biomarkers for therapy in advanced prostate cancer and explore emerging biomarkers.