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.

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.

Androgen receptor inhibition suppresses anti-tumor neutrophil response against bone metastatic prostate cancer via regulation of TβRI 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 (TβRI). High dose testosterone and genetic or pharmacologic TβRI 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.

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.

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.

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.

Early results from a phase 1, multicenter trial of PSCA-specific GoCAR T cells (BPX-601) in patients with metastatic castration-resistant prostate cancer (mCRPC)

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Background: Prostate stem cell antigen (PSCA) is expressed in >80% of metastatic prostate cancers. BPX-601 is an autologous PSCA-directed chimeric antigen receptor (CAR)-T cell immunotherapy engineered to express a rimiducid-inducible MyD88/CD40 costimulation switch to enhance T cell potency and persistence. Safety and activity of BPX-601 with rimiducid in mCRPC and pancreatic cancer is being assessed in an ongoing, phase 1/2 clinical trial (NCT02744287). Results from the first two prostate cancer cohorts are reported. Methods: Eligible mCRPC patients (pts) had progressed on ≥ 2 prior therapies including an androgen receptor antagonist and taxane. Using a 3+3 design, pts received lymphodepleting chemotherapy followed by a single-dose of 5 x 106 BPX-601 cells/kg and single or weekly doses of 0.4 mg/kg rimiducid infused over 2 hours beginning 7 days following cell infusion. Primary objective of phase 1 is to determine safety, tolerability and MTD or RP2D. Secondary objectives include characterization of clinical efficacy, PK of rimiducid and long-term safety. Biomarkers indicative of GoCAR-T cell expansion in blood, immune cell activity, and infiltration to tumor are being monitored. Results: As of Sept 2022, 8 pts received BPX-601 5x106 cells/kg; 3 and 5 pts received a single or weekly (range: 1-30) doses of rimiducid. Most common ≥ grade 3 adverse events were myelosuppression, attributed to lymphodepletion. All patients developed cytokine release syndrome (6 G1, 2 G3). Immune-effector cell associated neurotoxicity syndrome occurred and resolved in 2 pts (1 G1, 1 G4). One pt experienced a DLT of neutropenic sepsis (G5) with possible hemophagocytic lymphohistiocytosis (eg, IL-18, ferritin, M-CSF, fractalkine, MIP-1β and IL-1RA levels were elevated). Of 7 evaluable pts, PSA50 response was observed in 3 pts at Day 28. Preliminary RECIST-based results demonstrated partial response in 1, stable disease in 3, 1 progressive disease; at data cut off 2 had not reached imaging timepoint. One patient continues on study with SD after >9 months, with persistent evidence of rimiducid responsiveness. Peripheral blood BPX-601 cells expanded to an average of 3466 vector copies / μg DNA +/- 3109 during the first week with continued re-expansion to an average of 30234 copies/ug DNA +/- 67031) following rimiducid treatment. Serum IFN-γ, GM-CSF and IL-6 rapidly increased over 24 hours following rimiducid treatment (mean IFN-γ increase 26.9-fold ± 14.2) and subsequently diminished over 2 days. Conclusions: BPX-601, a PSCA-directed GoCAR-T cell product, has preliminary evidence of biologic activity with toxicity characteristic of previously reported CAR-T studies. Markers of rimiducid-induced GoCAR-T cell activation and proliferation were observed. Exploration of escalating weekly rimiducid doses > 0.4 mg/kg and BPX-601 cell doses is planned. Clinical trial information: NCT02744287 .

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.

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.

Abstract LB035: Understanding the mechanism of neuropilin2 upregulation in advanced prostate cancer

Background: Prostate cancer management involves administering Androgen Deprivation Therapy (ADT). Patients with advanced form of the disease become resistant to ADT and progress to a lethal phenotype called Castration Resistant Prostate Cancer (CRPC). Neuropilin-2 is upregulated in advanced prostate cancer. It has been implicated in decreasing the overall survival of such patients by inducing therapy-resistance.

Significance: Understanding how NRP2 is differentially expressed will uncover molecular pathways that can be targeted to develop a specific treatment strategy for better management of patients.

Experimental Design: We checked NRP2 expression in different prostate cancer cell lines {LNCaP, C4-2 and C4-2 P53/RB1 null cells (DKD cells)} and the level of methylation of the NRP2 promoter in these cells by pyrosequencing. We demethylated the NRP2 promoter by treatment with 5’Azacytidine and checked NRP2 mRNA expression. We analyzed the NRP2 promoter activity under demethylated conditions by transfecting cells with a demethylated NRP2 promoter construct using a GLuc dual-luciferase assay. Using Biobase we found DNA sequences for binding of transcription factors within the NRP2 promoter. RNA-Seq, RT-PCR was performed to identify potential transcription factors of NRP2(highly expressed in DKD cells). To validate SOX2 as a transcription factor for NRP2, we tested its binding to NRP2 promoter by ChIP-q-PCR. Requirement of SOX2 in transcribing NRP2 mRNA in C4-2 and DKD cells was tested by both knocking down or ectopically expressing SOX2. To determine whether demethylation of NRP2 promoter is a prerequisite for SOX2 binding, SOX2 was overexpressed in LNCaP cells following 5’Azacytidine and monitored the change in the NRP2 expression.

Results: NRP2 expression was low in LNCaP cells. It steadily increased in C4-2 cells with a steep rise in the DKD cells. Pyrosequencing showed a high level of DNA methylation in LNCaP cells compared to C4-2 cells. On treatment with 5’Azacytidine, NRP2 mRNA expression was upregulated in the LNCaP cells and it significantly rose in the C4-2 cells. Our dual-luciferase assay showed us that in C4-2 cells, the promoter activity of NRP2 upon demethylation went up causing a significant rise in Luciferase expression. RNA-seq and RT-PCR analysis showed high SOX2 levels in DKD cells indicating that SOX2 might play a role in elevating NRP2 expression in these cells. ChIP q-PCR indicated enriched binding of SOX2 in the NRP2 promoter in DKD cells. On silencing SOX2 in DKD cells, the expression of NRP2 was decreased. Analogous to this finding, overexpressing SOX2 in C4-2 cells caused significant rise in NRP2 expression, whereas in LNCaP cells, there was no change. Demethylation of NRP2 promoter and simultaneous overexpression of SOX2 in LNCaP lead to a significant increase in NRP2 mRNA suggesting the requirement of demethylated NRP2 promoter for SOX2 function.

Conclusion: The differential expression of NRP2 in advanced prostate cancer is a two-step process of initial demethylation of the DNA in the NRP2 promoter region, followed by binding of SOX2

Citation Format: Sanika Bodas, Ridwan Islam, Sreyashi Bhattacharya, Juhi Mishra, Dipanwita Das, Michael Muders, Samikshan Dutta, Benjamin A. Teply, Kaustubh Datta. Understanding the mechanism of neuropilin2 upregulation in advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB035.

Early discontinuation of abiraterone acetate/prednisone (AA/P) in localized prostate cancer

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Background: Data from STAMPEDE trial supporting systemic therapy intensification with long course AA/P was first presented in 2017. Overall survival benefit was confirmed in 2021. Our institution proceeded with early adoption of addition of 24 months of AA/P to ADT and radiotherapy (RT) in patients with high-risk localized or regional prostate cancer in 2017. In STAMPEDE, only 17% patients discontinued AA/P prior to completion of planned course. Outside of a clinical trial, whether patients adhere to this intense combination therapy that is associated with toxicities and expense is unknown. We hypothesized that adherence to long course AA/P in real-world practice in definitively treated prostate cancer would be poor. Methods: We performed a retrospective study for patients with clinically localized prostate cancer treated with AA/P combined with standard ADT and RT who had at least 6 months of follow-up data. Primary endpoint was rate of early discontinuation (prior to the 24mo) of AA/P. Secondary outcomes included rates of RT completion and disease recurrence and toxicity of intensive therapy. Reasons for early discontinuation were analyzed. Fisher's Exact, Chi-square analysis and Mann-Whitney tests were used to compare variables. SAS 9.4 was used for statistical analysis. Results: We identified 77 patients who met inclusion criteria, including 2 (2%) with high-risk, 30 (39%) with very high-risk, 19 (25%) with regional risk and 26 (34%) with locally recurrent disease after prostatectomy. AA/P was discontinued in 29 (38%) patients prior to completion of 24mo. Among those with early discontinuation, median duration of AA/P was 12.1 mo [0.1-21.7] and median duration of ADT was 17 mo[3.5-32.2]. Common reasons for early AA/P discontinuation included refractory hypokalemia (n = 4), diarrhea (n = 3), heart failure and fluid retention (n = 2 each) and quality of life deterioration (n = 8). Other reasons included hepatotoxicity, arrhythmia, osteoporotic fracture and financial toxicity (n = 1 each). All patients completed definitive RT. Only 1 of 77 patients had disease recurrence and had discontinued AA/P after 14 mo. A statistically significant association between age at diagnosis and treatment completion was noted(p = 0.01); each 1-year increase in age was associated with 9.4% decrease in odds of completing AA/P. Median age at diagnosis in those completing vs not completing AA/P was 65 vs 71 years. Conclusions: Very high rates of early discontinuation of AA/P were observed among patients with localized prostate cancer receiving definitive RT. Patients were less tolerant of toxicity in adjuvant setting compared to in a clinical trial or advanced disease. Shorter durations of AA/P appeared more acceptable but whether similar benefit is derived with a truncated course of AA/P is unknown. Future studies need to explore an optimal duration of AA/P that will reduce toxicity without compromising survival benefit.

Development of bullous pemphigoid following radiation therapy combined with nivolumab for renal cell carcinoma: A case report of abscopal toxicities

RATIONALE

Concern for immune-related adverse events from immunotherapy and radiation therapy are well-documented; however, side effects are mostly mild to moderate. However, high-grade, potentially life-threatening adverse events are increasing. While case reports regarding immunotherapy-related bullous pemphigoid (BP) have been rising, only 1 has described BP following concomitant use of both nivolumab and radiation therapy (RT). For that patient, nivolumab was used for 10 weeks prior to RT and development of PB followed 7 weeks later. This case presents a patient who tolerated nivolumab well for 38 months prior to developing BP less than 2 weeks after completing RT.

PATIENT CONCERNS

We present the case of DH, a 67-year-old gentleman on nivolumab for metastatic renal cell carcinoma to the lung since May of 2017. Following progressing lung nodules, the patient had his nivolumab paused and completed a course of short-beam radiation therapy. After restarting nivolumab post-radiation, the patient presented with itchy rash and blisters on his arm, legs, and trunk.

DIAGNOSIS

DH consulted dermatology following development of rash and was diagnosed with bullous dermatosis, likely bullous pemphigoid. Bullous pemphigoid following concomitant nivolumab (OPDIVO), despite prior tolerance and no history of autoimmune disease, was confirmed by biopsy a month later.

INTERVENTIONS

Initial treatment was betamethasone 0.05% cream mixed 1:1 with powder to form paste applied twice daily. Given progressive symptoms and confirmatory biopsy of BP, nivolumab was held and 100 mg doxycycline and 80 mg prednisone daily was prescribed for a week, reduced to 60 mg during the second week.

OUTCOMES

A week following discontinuation of nivolumab and beginning of doxycycline and prednisone, the blistering and rash was almost entirely resolved. Four months later, nivolumab was restarted and the patient continued low-dose tapering of prednisone until December. Since completing prednisone, the patient has shown no recurrence of bullous pemphigoid and has not developed any other immune-related adverse events to nivolumab upon rechallenge. Follow-up through October 2021 demonstrates the patient's sites of disease, both in- and out-field, have remained responsive to treatment.

LESSONS

Treating physicians should be aware of off-target effects of radiotherapy for oligoprogressive disease, which may include abscopal toxicities and the development of new immune-related adverse effects.

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.

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.

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.

Abstract 1409: Inhibiting Neuropilin-2 overcomes resistance to enzalutamide in prostate cancer

INTRODUCTION:Patients with advanced prostate cancer often report resistance to standard ARSI (Androgen Receptor Signaling Inhibitor) therapy. One reason for such therapy resistance is the development of splice variants of Androgen Receptor (AR). Additionally, studies have reported AR-independent signaling axis to play an important role in conferring therapy resistance in these cancers. The purpose of this study is to explore the underlying molecular mechanisms of resistance and develop an alternate therapeutic strategy for such patients.OBJECTIVES: In this study we investigated the role of Neuropilin-2 (NRP2), a receptor protein often upregulated in advanced prostate cancer, in imparting therapy-resistance to ARSI treatment (like enzalutamide). The final objective of this study is to develop a treatment strategy which targets NRP2 along with Enzalutamide treatment to increase treatment efficacy in therapy-resistant prostate cancer.

METHODS: To establish the expression pattern of NRP2 in advanced prostate cancer, we analyzed a dataset of 396 patients with advanced prostate cancer. Immunohistochemistry was performed on tissue samples to observe NRP2 localization within the cancer cells. NRP2 was knocked down using two independent siRNAs in various prostate cancer cell lines to determine the effect of NRP2 inhibition on cancer growth and survival. The knockdown was validated by Western Blot and RT-PCR. The efficacy of NRP2 inhibition was quantitated by measuring cell death using YO-PRO-I and PI assay for cellular apoptosis. In vitro tumorigenicity of cells after NRP2 inhibition in combination with enzalutamide was assessed using soft agar colony formation assay.

RESULTS:Our patient datasets showed a significant upregulation of NRP2, as well as poor cancer-specific survival, in advanced prostate cancer patients with higher Gleason scores. Immunohistochemistry analyses revealed a markedly high expression of NRP2 in the nucleus of cancer cells. We found that NRP2 nuclear translocation enabled transcription of novel oncogenes by interacting with AR. Knockdown of NRP2 was shown to bring about increased cell death in vitro. Inhibiting NRP2 was also seen to reduce AR-regulated oncogenesis. Cancer cell tumorigenicity was significantly reduced when NRP2 was inhibited in combination with enzalutamide, as evidenced by the decreased number of colonies in our colony formation assay.

CONCLUSION:Our results indicate that inhibiting NRP2 in combination with enzalutamide sensitizes the cells to ARSI treatment. Thus, NRP2 inhibition along with enzalutamide can be further explored as a treatment option for patients with treatment-refractory prostate cancer.

Citation Format: Sanika Bodas, Ridwan Islam, Navatha Polavaram, Sreyashi Bhattacharya, Michael Muders, Samikshan Dutta, Benjamin A. Teply, Kaustubh Datta. Inhibiting Neuropilin-2 overcomes resistance to enzalutamide in prostate cancer [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 1409.

A randomized phase II study comparing cisplatin and gemcitabine with or without berzosertib in patients with advanced urothelial carcinoma

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Background: Cisplatin with gemcitabine (CG) remains the standard upfront chemotherapy regimen for metastatic urothelial cancer (mUC). Preclinical synergy was noted between cisplatin and berzosertib, a selective ATR inhibitor. The current study sought to determine if the combination of berzosertib and CG could improve clinical outcomes in mUC. Methods: An open-label, randomized study was conducted across 23 centers in the United States through the Experimental Therapeutics Clinical Trials Network of the National Cancer Institute. Key eligibility criteria included confirmed mUC, no prior cytotoxic therapy for metastatic disease, ≥ 12 months since perioperative therapy and eligibility for cisplatin based on standard criteria. Patients (pts) were randomized to receive either CG alone (control arm) or CG plus berzosertib (experimental arm). In the control arm, 70 mg/m2 of cisplatin was given on day 1 and gemcitabine at 1000 mg/m2 on days 1 and 8 of a 21-day cycle. In the experimental arm, 60 mg/m2 of cisplatin was given on day 1, gemcitabine at 875 mg/m2 on days 1 and 8 and berzosertib at 90 mg/m2 on days 2 and 9 of a 21-day cycle. The primary endpoint of the study was progression-free survival (PFS), with secondary endpoints including response rate (RR), overall survival (OS) and toxicity. Results: A total of 87 pts (median age 67; M:F 68:19) were randomized; 41 pts received CG alone while 46 received CG with berzosertib. Visceral metastases were present in 49% of pts and 52%, 45% and 3% of pts were Bajorin risk 0, 1 and 2, respectively. Median PFS was 8.0 months for both arms (Bajorin risk adjusted hazard ratio [HR] 1.22, 95% confidence interval [CI] 0.72-2.08). RR was 54%(4 CR, 21 PR) in the CG with berzosertib arm and 63% (4 CR, 22 PR) in CG alone arm (P = 0.66). Median OS was shorter with CG with berzosertib as compared to CG alone (14.4 versus 19.8 months; Bajorin risk adjusted HR 1.42, 95%CI 0.76-2.68). Notably higher rates of grade 3/4 thrombocytopenia (59% vs 39%) and neutropenia (37% vs 27%) were observed with CG plus berzosertib compared to CG alone. Higher rates of toxicity-related discontinuation were seen in the experimental arm (24% vs 15%), and the median cumulative cisplatin dose in the experimental arm was 250 mg/m2, as compared to 370 mg/m2 in the control arm (P < 0.001). Conclusions: No improvement in PFS was observed with the addition of berzosertib to CG, and a trend towards inferior survival was observed. These results suggest caution in reducing the starting dose of cytotoxic therapy to accommodate addition of a myelosuppressive agent, as in the experimental arm of this study. Clinical trial information: NCT02567409.

Can patients with advanced malignancy and poor performance status benefit from nivolumab plus ipilimumab as a palliative treatment?

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Background: Performance status (e.g. Eastern Cooperative Oncology Group [ECOG] score) is a predictive tool used to determine whether a patient may benefit from cytotoxic chemotherapy. The toxicity profile of immunotherapy is different, and less is known about whether performance status (PS) is similarly associated with toxicity and benefit. Nonetheless, most clinical trials for immune checkpoint inhibitors have excluded patients with poor PS. Emerging data by our group and others has linked poor PS with lack of response and decreased survival with anti-PD-1/L1 agents, but whether combination therapy abrogates the poor outcomes of PD1 only therapy is unknown. Methods: We conducted a retrospective cohort study of patients with metastatic cancer who received ipilimumab plus nivolumab at our institution between January 2014-December 2020. We compared outcomes between those with good PS (Group A, ECOG PS 0-1) and poor PS (Group B, ECOG PS ≥ 2). Our primary outcomes were overall survival (OS) and incidence of grade 3-4 immune-related adverse events (irAEs). Other outcomes included objective response rates and need for hospitalization. We utilized the Kaplan-Meyer method for time to survival analysis and exact Pearson Chi-squared testing for response, toxicity, and hospitalization analysis. Results: A total of 129 patients were identified with a mean age of 59.9 years. Among them were 73 males (57%) and 56 females (43%). Malignant melanoma was the most common malignancy (39%) followed by renal cell carcinoma (27%), small cell lung cancers (10%), non-small cell lung cancers (9%), and the rest with other histologies. 113 patients (87.6%) were in group A and 16 (12.4%) in group B. Across all tumor types, patients in Group B had significantly worse OS compared to group A (HR 0.24 [0.13-0.48], P = < 0.0001). Group B similarly had higher rates of hospitalization compared to group A (94% vs 56%, P = 0.0048). Interestingly, irAEs were not driving these hospitalizations, with a trend toward lower rates of irAEs in the poor PS group (19% vs 46% in Group A, P = 0.057). The overall response rate in group B was numerically lower (6% vs 26% in group A, p = 0.1). Conclusions: Our study showed that using ipilimumab plus nivolumab in patients with poor PS was associated with significantly poorer OS and higher rates of hospitalizations. irAEs were not increased in the poor PS group, suggesting a lack of treatment efficacy seemed to driving these poor outcomes. Extrapolation of clinical trial data for ipilimumab-nivolumab to a broader population including those with poor PS should be done with caution. Unfortunately, our data showed that most patients with poor PS were not adequately palliated with ipilimumab-nivolumab.

Tumor- and osteoclast-derived NRP2 in prostate cancer bone metastases

Understanding the role of neuropilin 2 (NRP2) in prostate cancer cells as well as in the bone microenvironment is pivotal in the development of an effective targeted therapy for the treatment of prostate cancer bone metastasis. We observed a significant upregulation of NRP2 in prostate cancer cells metastasized to bone. Here, we report that targeting NRP2 in cancer cells can enhance taxane-based chemotherapy with a better therapeutic outcome in bone metastasis, implicating NRP2 as a promising therapeutic target. Since, osteoclasts present in the tumor microenvironment express NRP2, we have investigated the potential effect of targeting NRP2 in osteoclasts. Our results revealed NRP2 negatively regulates osteoclast differentiation and function in the presence of prostate cancer cells that promotes mixed bone lesions. Our study further delineated the molecular mechanisms by which NRP2 regulates osteoclast function. Interestingly, depletion of NRP2 in osteoclasts in vivo showed a decrease in the overall prostate tumor burden in the bone. These results therefore indicate that targeting NRP2 in prostate cancer cells as well as in the osteoclastic compartment can be beneficial in the treatment of prostate cancer bone metastasis.

Randomized Phase III Trial of Gemcitabine and Cisplatin With Bevacizumab or Placebo in Patients With Advanced Urothelial Carcinoma: Results of CALGB 90601 (Alliance)

PURPOSE

The combination of gemcitabine and cisplatin (GC) is a standard therapy for metastatic urothelial carcinoma. Based on data that angiogenesis plays a role in urothelial carcinoma growth and progression, a randomized placebo-controlled trial was performed with the primary objective of testing whether patients treated with GC and bevacizumab (GCB) have superior overall survival (OS) than patients treated with GC and placebo (GCP).

PATIENTS AND METHODS

Between July 2009 and December 2014, 506 patients with metastatic urothelial carcinoma without prior chemotherapy for metastatic disease and no neoadjuvant or adjuvant chemotherapy within 12 months were randomly assigned to receive either GCB or GCP. The primary end point was OS, with secondary end points of progression-free survival, objective response, and toxicity.

RESULTS

With a median follow-up of 76.3 months among alive patients, the median OS was 14.5 months for patients treated with GCB and 14.3 months for patients treated with GCP (hazard ratio for death = 0.87; 95% CI, 0.72 to 1.05; two-sided stratified log-rank P = .14). The median progression-free survival was 8.0 months for GCB and 6.7 months for GCP (hazard ratio = 0.77; 95% CI, 0.63 to 0.95; P = .016). The proportion of patients with grade 3 or greater adverse events did not differ significantly between both arms, although increased bevacizumab-related toxicities such as hypertension and proteinuria occurred in the bevacizumab-treated arm.

CONCLUSION

The addition of bevacizumab to GC did not result in improved OS. The observed median OS of about 14 months is consistent with prior phase III trials of cisplatin-based chemotherapy.

Targeting treatment options for castration-resistant prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in U.S. men in 2020. Androgen-deprivation therapy (ADT) is the standard of care for metastatic PCa. Unfortunately, PCa relapse often occurs one to two years after initiation of ADT, resulting in the development of castration-resistant PCa (CRPCa), a lethal disease. While several anticancer agents such as docetaxel, abiraterone acetate, and enzalutamide are currently utilized to extend a patient's life after development of CRPCa, patients will eventually succumb to the disease. Hence, while targeting androgen signaling and utilization of docetaxel remain the most crucial agents for many of these combinations, many studies are attempting to exploit other vulnerabilities of PCa cells, such as inhibition of key survival proteins, anti-angiogenesis agents, and immunotherapies. This review will focus on discussing recent advances on targeting therapy. Several novel small molecules will also be discussed.

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.

Sildenafil Potentiates the Therapeutic Efficacy of Docetaxel in Advanced Prostate Cancer by Stimulating NO-cGMP Signaling

PURPOSE

Docetaxel plays an indispensable role in the management of advanced prostate cancer. However, more than half of patients do not respond to docetaxel, and those good responders frequently experience significant cumulative toxicity, which limits its dose duration and intensity. Hence, a second agent that could increase the initial efficacy of docetaxel and maintain tolerability at biologically effective doses may improve outcomes for patients.

EXPERIMENTAL DESIGN

We determined phosphodiesterase 5 (PDE5) expression levels in human and genetically engineered mouse (GEM) prostate tissues and tumor-derived cell lines. Furthermore, we investigated the therapeutic benefits and underlying mechanism of PDE5 inhibitor sildenafil in combination with docetaxel using in vitro, Pten conditional knockout (cKO), derived tumoroid and xenograft prostate cancer models.

RESULTS

PDE5 expression was higher in both human and mouse prostate tumors and cancer cell lines compared with normal tissues/cells. In GEM prostate-derived cell lines, PDE5 expression increased from normal prostate (wild-type) epithelial cells to androgen-dependent and castrated prostate-derived cell lines. The addition of physiologically achievable concentrations of sildenafil enhanced docetaxel-induced prostate cancer cell growth inhibition and apoptosis in vitro, reduced murine 3D tumoroid growth, and in vivo tumorigenicity as compared with docetaxel alone. Furthermore, sildenafil enhanced docetaxel-induced NO and cGMP levels thereby augmenting antitumor activity.

CONCLUSIONS

Our results demonstrate that sildenafil's addition could sensitize docetaxel chemotherapy in prostate cancer cells at much lesser concentration than needed for inducing cell death. Thus, the combinatorial treatment of sildenafil and docetaxel may improve anticancer efficacy and reduce chemotherapy-induced side-effects among patients with advanced prostate cancer.

Cardiovascular risks and toxicity - The Achilles heel of androgen deprivation therapy in prostate cancer patients

Androgen deprivation therapy (ADT) is the primary systemic therapy for treating locally advanced or metastatic prostate cancer (PCa). Despite its positive effect on PCa patient survival, ADT causes various adverse effects, including increased cardiovascular risk factors and cardiotoxicity. Lifespans extension, early use of ADT, and second-line treatment with next-generation androgen receptor pathway inhibitors would further extend the duration of ADT and possibly increase the risk of ADT-induced cardiotoxicity. Meanwhile, information on the molecular mechanisms underlying ADT-induced cardiotoxicity and measures to prevent it is limited, mainly due to the lack of specifically designed preclinical studies and clinical trials. This review article compiles up-to-date evidence obtained from observational studies and clinical trials, in order to gain new insights for deciphering the association between ADT use and cardiotoxicity. In addition, potential cardioprotective strategies involving GnRH receptors and second messenger cGMP are discussed.

RESTORE: A single-arm, open-label phase II trial of bipolar androgen therapy (BAT) in men with metastatic castration resistant prostate cancer (mCRPC)—A comparison of post-abiraterone (Abi) versus post-enzalutamide (Enza) patients (Pts)

5576

Background: A paradoxical inhibition of cell growth has been observed in both androgen-sensitive and castration resistant prostate cancer cell lines following the addition of high-dose testosterone.We have conducted several clinical trials investigating a mode of supraphysiologic testosterone therapy termed, BAT, in which testosterone levels are rapidly driven to the supraphysiologic range followed by a return to near-castrate levels over 28-day treatment cycles with favorable results. We previously reported the efficacy of BAT in mCRPC pts that were progressing on enza. In this study, we compared the effect of BAT in mCRPC pts whose last therapy was abi vs. enza. In addition, we examined the benefit of abi or enza rechallenge after progression on BAT. Methods: 59 mCRPC pts (n = 29 post abi; n = 30 post enza) were enrolled and received at lease one dose of BAT monotherapy, 400mg intramuscularly every 28 days. After clinical or radiographic progression on BAT, pts were rechallenged with the AR targeted therapy to which they were most recently resistant. The co-primary endpoints were a 50% decline in PSA from baseline (PSA50) for BAT and for enza/abi rechallenge. Results: 5/29 (17.2%) of post-abi pts compared to 9/30 (30%) in the post enza group achieved a PSA50 response (P = 0.36). Post BAT rechallenge with abi (n = 19) or enza (n = 22) resulted in a PSA50 response rate of 15.8% (n = 3) and 68.2% (n = 15), respectively (P = 0.001). The total duration of benefit (i.e. PFS on BAT + PFS on rechallenge = “PFS2”) was significantly longer in the post enza vs. post-abi patients (Median PFS2: 12.75 vs. 8.125 months; P = 0.04. Lastly, AR-V7 negative (n = 42) pts has a significantly longer median PFS2 compared to AR-V7 positive (n = 10) pts. (10.3 vs. 7.1 months, P = 0.005). Conclusions: Our data suggest that BAT may be more effective at resensitizing mCRPC to direct AR antagonists (i.e. enza) compared to abi. Detection of AR-V7 portended a worse outcome on BAT/rechallenge. Further clinical study is warranted. Clinical trial information: NCT02090114 . [Table: see text]

Impact of performance status on response and survival among patients receiving checkpoint inhibitors for advanced solid tumors

12028

Background: Clinical trials leading to the approval of immune checkpoint inhibition (ICI) have almost exclusively been performed in patients with good performance status (ECOG PS of 0-1). However, ICI remains an attractive option for patients with advanced tumors and poor performance status, considering their overall tolerability. While use of ICI in patients with poor PS (ECOG PS of 2 or greater) has been rapidly adopted, whether these patients derive the same benefits as expected in the studied populations is largely unknown. We therefore performed an institutional retrospective analysis of all patients treated with palliative single agent anti-PD1 or anti-PDL1 to determine response and survival for those with poor performance status. Methods: We retrospectively identified patients with advanced solid tumor malignancies who were treated with ICI monotherapy with palliative intent at our institution between 2015-2019. The primary objective was to compare overall survival (OS) for patients with good PS (ECOG PS 0-1) with those with poor PS (ECOG PS 2 or 3-4). The log-rank test compared the survival among patients with different ECOG PS. In addition, we used a proportional hazards model to assess association between ECOG PS and the OS with adjustment for age, gender, and smoking status. A secondary objective was to compare overall response rates (ORR) of the three ECOG PS groups which were evaluated with a binary rate model. Results: We identified 266 patients treated with ICI, 87 with NSCLC, 34 with melanoma, 33 with RCC, 24 with bladder cancer, 22 with head/neck cancer, and the rest with other histologies. 187 (70%) were ECOG PS 0-1, 62 (23%) were ECOG PS 2, and 17 (7%) were ECOG PS 3-4. 89 of these patients (33%) were still alive at time of last follow-up. Across all tumor types, patients with ECOG PS 0-1 had superior survival compared to ECOG PS 2 (median survival 12.4 months vs 4.6 months, HR 0.41, p < 0.001). Median survival for ECOG PS 3-4 was lower at 2.3 months. The ORR for ECOG PS 0-1 (23%) was significantly higher to that of ECOG PS 2 (6%, p = 0.02). ORR for ECOG PS 3-4 was 12%. Conclusions: Despite the appeal of ICI for patients with advanced malignancy and poor performance status, outcomes were poor. Survival and objective response rates for patients with ECOG PS 2 and higher were significantly worse than those with ECOG PS 0-1. ICI treatment comes with cost, including potentially forgoing early hospice referral or optimal support at the end of life. Prospective trials defining the activity and role of ICI in poor PS are urgently needed.

Targeting resistant prostate cancer with ATR and PARP inhibition (TRAP trial): A phase II study

TPS254

Background: Inhibition of poly(ADP-ribose) polymerase (PARP) shows promise in prostate cancer, but is limited to the ~20% of men with defects in genes encoding for DNA repair proteins BRCA1, BRCA2 or ATM (homologous recombination defect positive, HRD+). The effect is modest for HRD+ patients with a progression free survival of ~7 months. Pharmacologically simulating genetic DNA repair defects may expand who benefits to homologous recombination defect negative (HRD-) patients and improve HRD+ response. The ataxia telangiectasia and Rad3-related protein (ATR) is ideal with its roles in cell cycle regulation, replication fork resolution and both single and double strand break repair. Preclinical studies on HRD-/HRD+ cell lines support this. We hypothesize co-inhibition of ATR and PARP will respond regardless of HRD status. Methods: TRAP is a prospective, multi-institutional, phase 2 clinical trial testing AZD6738 combined with olaparib in HRD+ and HRD- mCRPC patients. Primary endpoint is the response rate (RR) by RECIST radiographic response or PSA decline ≥50% in 35 HRD- patients, with a secondary objective of RR in 12 HRD+ patients. HRD+ is mono/biallelic loss of ATM or biallelic loss of BRCA1/2. Tissue based sequencing is done unless completed prior in mCRPC, known BRCA germline loss, treating provider deems biopsy unsafe or biopsy fails. Those unable or failing biopsy are designated as HRD-, but BRCA1/2 and ATM are tested via circulating tumor DNA in a commercial test. Eligible patients must progress after ≥1 line of mCRPC therapy. Progression on a second generation anti-androgen (e.g. apalutamide), abiraterone or within 6 months of docetaxel in hormone sensitive disease are eligible. Treatment entails 160 mg PO daily of AZD6738 on days 1-7 and 300 mg PO BID of olaparib on days 1-28 of a 28-day cycle. Statistical analysis will provide RR with 95% binomial confidence intervals. Analysis of tumor specimens, circulating tumor cells and DNA will be performed for predictors of response and acquired resistance. The study is at four sites in the US, participates in the Prostate Cancer Clinical Trials Consortium, LLC, is managed by the University of Michigan and funded by AstraZeneca. Clinical trial information: NCT03787680.

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.

Interim results from a phase 2 study of olaparib (without ADT) in men with biochemically-recurrent prostate cancer after prostatectomy, with integrated biomarker analysis

5045

Background: Pts with biochemically-recurrent (BCR) prostate cancer after local therapy with a PSA doubling time (PSADT) of ≤6 mo are likely to develop metastases and death from their disease. We hypothesized that the PARP inhibitor olaparib would be effective as a non-hormonal therapy for biomarker-unselected pts with BCR after prostatectomy, the first study of PARP inhibition in the hormone-sensitive setting. We report pre-specified interim results from the first stage of the trial. Methods: This investigator-initiated multicenter study (NCT03047135) enrolled pts with non-metastatic BCR after prostatectomy, with a PSADT of ≤6 mo. PSA had to be ≥1.0 ng/mL, with T ≥150 ng/dL. Pts received olaparib 300 mg twice daily (without ADT), until a doubling of their PSA or metastatic progression. The primary endpoint was confirmed ≥50% PSA decline (PSA50 response). Secondary endpoints included safety, minor PSA response (1-50% reduction), and PSA progression-free survival. Integrated biomarker analyses included somatic DNA sequencing, RNA expression analysis and IHC for DNA damage markers, using prostatectomy specimens. The study was designed to enroll a biomarker-unselected population using a staged-adaptive design, with up to 50 pts. In the first stage, ≥3 PSA50 responses out of 20 pts were required to proceed to the second stage; otherwise enrichment with biomarker-selected pts would occur. Results: Between 5/2017 and 11/2018, 20 men (median age, 65) enrolled in the first stage, with a median follow-up of 6 (range, 3-16) mo. Median PSADT was 3.1 mo, and 55% had Gleason ≥8 cancers. Seven men (35%) had BRCA2/ATM mutations. Three men (15%) had PSA50 responses (all had BRCA2 muts – 2 had complete PSA responses), and 4 other men (20%) had minor PSA responses. Median PSA progression-free survival was greater in men with vs. without BRCA2/ATM muts (9 vs. 4 mo; P= 0.02). Common toxicities of olaparib included fatigue, nausea, anemia and leukopenia; 2 men required a dose reduction. Conclusions: Olaparib (without ADT) was tolerable and showed activity in hormone-sensitive BCR prostate cancer, especially in men with BRCA2 muts. Second-stage enrolment is ongoing. Clinical trial information: NCT03047135.

Phase II study of olaparib (without ADT) in men with high-risk biochemically-recurrent prostate cancer following prostatectomy, with integrated biomarker analysis

TPS386

Background: Patients with a high-risk biochemical recurrence (BCR) of prostate cancer after local therapy, defined by a rapid PSA doubling time (≤6 mo), are likely to experience metastases and subsequently death from their disease. Early use of androgen deprivation therapy (ADT) in these patients is controversial and is associated with side effects. Non-hormonal therapies that alter the natural history of BCR disease are needed. Olaparib is a PARP inhibitor that produces responses in some men with advanced prostate cancer, particularly those with dysregulation of DNA repair genes (i.e. synthetic lethality). Preclinical data support the activity of olaparib in prostate cancer beyond the DNA repair-deficient subset, yet the optimal biomarker for treatment selection is unknown. We hypothesized that olaparib monotherapy would show activity in men with high risk BCR and sought to further define the optimal patient population for olaparib in this setting. Methods: In this investigator-initiated multi-center open-label study, eligible patients will have non-metastatic BCR after prostatectomy, with a PSA doubling time of ≤6 mo. Prior limited ADT is allowed, but testosterone must have recovered (≥150 ng/dL). Patients will receive 300mg olaparib twice daily, with disease evaluation by PSA monthly and radiographic studies every 6 mo. Patients continue olaparib until evidence of metastasis or until PSA doubles from baseline, with a minimum exposure of 3 months. The primary endpoint is the rate of decline in PSA to ≥50% from baseline (PSA50 response). Secondary endpoints include safety, progression-free survival, and the rate of durable responses. Exploratory analysis will involve biomarker discovery including somatic DNA mutation analysis, RNA expression analysis, and immunohistochemistry for DNA damage markers, done on prostatectomy specimens. The study will initially enroll an all-comer (unselected) population and will then proceed via a staged-adaptive design; if futility is observed in the all-comer population at interim analyses, enrichment with biomarker-selected patients will occur. Clinical trial information: NCT03047135.

Visceral metastases on abiraterone vs. placebo: A post-hoc analysis of mode of radiographic progression in COU-AA-302

194

Background: Abiraterone prolongs survival in patients with prostate cancer due to its potent inhibition of androgen synthesis. We previously observed increased rates of visceral metastatic disease at the time of progression on abiraterone compared to baseline, a poor prognostic feature associated with non-AR dependent prostate cancer. We hypothesized that the rate of development of visceral disease was increased with abiraterone compared to other treatments without potent androgen signaling inhibition. In order to test this, we examined time to visceral disease among patients treated with abiraterone vs placebo on the COU-AA-302 trial. Methods: We performed a post-hoc analysis of radiographic progression data for the phase 3 study of abiraterone vs placebo, via a data sharing agreement through the Yale Open Data Access Project. Data were censored at end of study treatment. The distribution of cumulative incidence for visceral metastases was calculated by the Kaplan-Meier method and compared with log-rank testing. Multivariable cox regression analysis was performed to assess for independent association of study treatment (abiraterone vs placebo) with the development of visceral metastases. Results: Median follow-up was 12.5mo, and 84 of 1088 patients developed visceral metastases. Univariate log-rank testing showed no difference in time to visceral metastasis between groups (p = 0.97). 1- and 3-yr cumulative incidence of visceral metastases were estimated at 6.4% and 15.6% for abiraterone and 4.6% and 17.0% for placebo, respectively. Study treatment was not a significant predictor for the development of visceral metastasis (HR 0.76; 95% CI 0.47-1.21) after adjustment for baseline metastatic disease burden (soft tissue and bone) and LDH. Conclusions: Abiraterone was not associated with increased visceral metastases at progression compared to placebo. These data give more confidence to oncologists that abiraterone is not driving prostate cancer to an aggressive phenotype characterized by visceral metastases - a finding that is particularly important as abiraterone is increasingly used in early disease states.

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.

Treatment strategies for DNA repair-deficient prostate cancer

INTRODUCTION

Common recurrent genetic alterations have been identified in prostate cancer through comprehensive sequencing efforts, and the prevalence of mutations in DNA repair pathway genes in patients with advanced and metastatic disease approaches 20-25%. Identification of these underlying DNA repair defects may present unique treatment opportunities for patients, both in terms of standard-of-care treatments and selected investigational agents. Areas covered: We review our current understanding of the genomic landscape of prostate cancer, with special attention to alterations in DNA repair pathway genes in metastatic castration-resistant disease. For patients with tumors deficient in homologous recombination repair, potential opportunities for treatment include platinum chemotherapy, poly(ADP) ribose polymerase (PARP) inhibitors, bipolar androgen therapy, and maybe immune checkpoint blockade therapy. In addition, tumors with mismatch repair defects (i.e. microsatellite instability) may be particularly susceptible to checkpoint blockade immunotherapy. Expert commentary: We anticipate that genomic profiling of tumors will become necessary to guide treatment of advanced prostate cancer in the coming years. Work is needed to define the optimal tissue to test, and to define the natural history of tumors with specific genetic defects. The prognostic and therapeutic importance of germline vs somatic DNA repair alterations, and mono-allelic vs bi-allelic inactivation, also remains unclear. Finally, optimal strategies to sequence or combine targeted agents for these patients with 'actionable' mutations are now needed.

Phase II study of bipolar androgen therapy (BAT) in men with metastatic castration-resistant prostate cancer (mCRPC) and progression on enzalutamide (enza)

5017

Background: Androgen receptor (AR) overexpression is a common adaptive resistance mechanism in mCRPC. High dose testosterone in this setting may induce tumor responses and restore normal AR expression. To evaluate BAT, we enrolled men with mCRPC progressing on enza to assess (1) responses to BAT and (2) enza re-challenge after BAT. Methods: Eligible men had minimally symptomatic mCRPC with progression on enza. Subjects received testosterone cypionate 400mg IM every 28d and continued gonadal suppression, until progression. Subjects were evaluated with PSAs each cycle, and CT/bone scans every 3 cycles. Upon progression on BAT, men were re-challenged with enza. The co-primary endpoints were > 50% PSA responses (PSA50) to BAT and PSA50 to enza re-challenge. The null hypothesis was a PSA50 rate of 5% for both endpoints, with alternative hypotheses of 20% to BAT and 25% to enza. 30 subjects were required for 90% and 83% power, respectively, with overall type 1 error of 0.1. Secondary endpoints were safety, objective response, progression-free survival (PFS), and effect on circulating tumor cell-based AR and AR-V7 expression. Results: 30 eligible subjects were accrued (2014-2016). No dose limiting toxicities were seen. 2 subjects had transient pain flares after BAT initiation. Common grade 1-2 adverse events (AE) were musculoskeletal pain (40%), increased hemoglobin (37%), breast tenderness (17%) and rash (17%). 3 Grade 3-4 AE potentially attributable to BAT occurred (pulmonary embolism, NSTEMI, and urinary obstruction). 9/30 men (30% [95% CI: 17-48%]) achieved a PSA50 to BAT. 5/14 men (36%) with measurable disease had an objective response by RECIST 1.1. The median clinical/radiographic PFS on BAT was 8.6 months. 21 subjects proceeded to enza re-challenge, yielding 15 PSA50 responses (54% by intention to treat [95% CI: 34-69%]), with a PFS of 4.8 months. 1/3 AR-V7+ subjects responded to BAT, and all had decreased AR-V7/AR ratios (2 converted to AR-V7-) after 3 cycles. Conclusions: The study met its primary endpoints, demonstrating preliminary efficacy of BAT in men with progressive mCRPC after enza. A randomized study comparing BAT to enza in mCRPC is ongoing. Clinical trial information: NCT02090114.

Novel mechanism-based therapeutics for androgen axis blockade in castration-resistant prostate cancer

PURPOSE OF REVIEW

Understanding the mechanisms by which castration-resistant prostate cancer (CRPC) progresses provides an opportunity to identify novel therapeutic strategies to treat this disease. This understanding has led to approaches to attack prostate cancer's androgen axis in unique ways. This review will examine the classes of novel therapies for androgen axis blockade in CRPC, with a particular focus on the unique characteristics of drugs in various stages of clinical development.

RECENT FINDINGS

The success of abiraterone and enzalutamide has stimulated multiple investigations into novel approaches to attack the androgen-signaling pathway. Drugs under development include cytochrome P17 inhibitors with 17,20-lyase specificity, androgen receptor antagonists that are active against mutated and constitutively active splice variant forms of the protein, androgen receptor degraders, and bromodomain/bromodomain extra-terminal inhibitors that prevent chromatin binding of activated receptors. The clinical development of several of these experimental agents is reviewed.

SUMMARY

Given the unique mechanisms of action for drugs in development, and the possibility that the novel agents may be active in the setting of common resistance mechanisms, treatment options for patients are likely to expand greatly in the coming years. Future studies should prioritize combinations of agents with unique mechanisms of action to optimize outcomes for patients, and should rely on precision-medicine approaches to target known molecular alterations.

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.

The influence of prednisone on the efficacy of docetaxel in men with metastatic castration-resistant prostate cancer

BACKGROUND

Prednisone and other corticosteroids can provide palliation and tumor responses in patients with prostate cancer. The combination of docetaxel and prednisone was the first treatment shown to prolong survival in men with metastatic castration-resistant prostate cancer (mCRPC). Since the approval of docetaxel in 2004, additional treatments are available, including abiraterone, which is also administered with prednisone. Therefore, patients are increasingly likely to have prednisone therapy several times throughout their disease course, and the contribution of prednisone to the efficacy of docetaxel is unknown.

METHODS

We conducted a retrospective study of patients with mCPRC treated with docetaxel at our institution between 2004–2014. Patients were divided into 2 cohorts based upon whether prednisone was co-administered with docetaxel. Cohorts were further stratified based upon prior prednisone (with abiraterone) or hydrocortisone (with ketoconazole) use. The primary endpoint was clinical/radiographic progression-free survival (PFS). The secondary endpoints were >50% PSA response rate and PSA progression-free survival (PSA-PFS). A multivariable cox regression model was constructed to determine if prednisone use was independently predictive of PFS.

RESULTS

We identified 200 consecutive patients for inclusion in the study: 131 men received docetaxel with prednisone and 69 received docetaxel alone. The docetaxel-prednisone cohort had superior PFS compared to the docetaxel-alone cohort (median PFS: 7.8 vs 6.2 months, HR 0.68 [95% CI 0.48–0.97], p=0.03). Prednisone was associated with a reduced risk of progression on docetaxel in the propensity score-weighted multivariable Cox model (p=0.002). Among abiraterone- or ketoconazole-pretreated patients, no difference in PFS was observed between prednisone-containing and non-prednisone containing cohorts (median PFS: 7.1 vs 6.3 months, HR 0.96 [95% CI 0.59–1.57], p=0.87).

CONCLUSIONS

The incorporation of prednisone potentially augments the efficacy of docetaxel in patients with mCRPC. We hypothesize that this advantage is limited to patients who have not previously received corticosteroids. Prospective confirmation is needed.

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.

Systemic therapy for bladder cancer - a medical oncologist's perspective

Advanced bladder cancer, both muscle-invasive localized disease and metastatic disease, is managed with systemic chemotherapy. Cisplatin-based multi-agent chemotherapy remains the cornerstone for systemic therapy. MVAC (methotrexate-vinblastine-doxorubicin-cisplatin) has been most rigorously studied, both neoadjuvantly and for palliation of metastatic disease. For metastatic disease, cisplatin-gemcitabine (GC) has compared favorably to MVAC due to improved tolerability with similar efficacy. GC has been adopted as standard therapy. Neoadjuvant chemotherapy for muscle-invasive bladder cancer improves survival among those patients eligible to receive cisplatin. Adjuvant chemotherapy is difficult to administer effectively given morbidity of radical cystectomy, and studies have shown mixed results about its benefit. Non-cisplatin regimens have been investigated but remain experimental and reserved for those not candidates for cisplatin in the metastatic setting. While multiple agents have been studied after metastatic disease progression after cisplatin-based therapy, there remain no FDA-approved therapies for the second line. Future trials with anti-VEGF therapy and immunotherapy are actively being investigated. This review examines the systemic therapy available to oncologists with current evidence and future directions.

Engineering of targeted nanoparticles for cancer therapy using internalizing aptamers isolated by cell-uptake selection

One of the major challenges in the development of targeted nanoparticles (NPs) for cancer therapy is to discover targeting ligands that allow for differential binding and uptake by the target cancer cells. Using prostate cancer (PCa) as a model disease, we developed a cell-uptake selection strategy to isolate PCa-specific internalizing 2'-O-methyl RNA aptamers (Apts) for NP incorporation. Twelve cycles of selection and counter-selection were done to obtain a panel of internalizing Apts, which can distinguish PCa cells from nonprostate and normal prostate cells. After Apt characterization, size minimization, and conjugation of the Apts with fluorescently labeled polymeric NPs, the NP-Apt conjugates exhibit PCa specificity and enhancement in cellular uptake when compared to nontargeted NPs lacking the internalizing Apts. Furthermore, when docetaxel, a chemotherapeutic agent used for the treatment of PCa, was encapsulated within the NP-Apt, a significant improvement in cytotoxicity was achieved in targeted PCa cells. Rather than isolating high-affinity Apts as reported in previous selection processes, our selection strategy was designed to enrich cancer cell-specific internalizing Apts. A similar cell-uptake selection strategy may be used to develop specific internalizing ligands for a myriad of other diseases and can potentially facilitate delivering various molecules, including drugs and siRNAs, into target cells.

Formulation of functionalized PLGA-PEG nanoparticles for in vivo targeted drug delivery

Nanoparticle (NP) size has been shown to significantly affect the biodistribution of targeted and non-targeted NPs in an organ specific manner. Herein we have developed NPs from carboxy-terminated poly(d,L-lactide-co-glycolide)-block-poly(ethylene glycol) (PLGA-b-PEG-COOH) polymer and studied the effects of altering the following formulation parameters on the size of NPs: (1) polymer concentration, (2) drug loading, (3) water miscibility of solvent, and (4) the ratio of water to solvent. We found that NP mean volumetric size correlates linearly with polymer concentration for NPs between 70 and 250 nm in diameter (linear coefficient=0.99 for NPs formulated with solvents studied). NPs with desirable size, drug loading, and polydispersity were conjugated to the A10 RNA aptamer (Apt) that binds to the prostate specific membrane antigen (PSMA), and NP and NP-Apt biodistribution was evaluated in a LNCaP (PSMA+) xenograft mouse model of prostate cancer. The surface functionalization of NPs with the A10 PSMA Apt significantly enhanced delivery of NPs to tumors vs. equivalent NPs lacking the A10 PSMA Apt (a 3.77-fold increase at 24h; NP-Apt 0.83%+/-0.21% vs. NP 0.22%+/-0.07% of injected dose per gram of tissue; mean+/-SD, n=4, p=0.002). The ability to control NP size together with targeted delivery may result in favorable biodistribution and development of clinically relevant targeted therapies.

Targeted nanoparticle-aptamer bioconjugates for cancer chemotherapy in vivo

Targeted uptake of therapeutic nanoparticles in a cell-, tissue-, or disease-specific manner represents a potentially powerful technology. Using prostate cancer as a model, we report docetaxel (Dtxl)-encapsulated nanoparticles formulated with biocompatible and biodegradable poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-b-PEG) copolymer and surface functionalized with the A10 2'-fluoropyrimidine RNA aptamers that recognize the extracellular domain of the prostate-specific membrane antigen (PSMA), a well characterized antigen expressed on the surface of prostate cancer cells. These Dtxl-encapsulated nanoparticle-aptamer bioconjugates (Dtxl-NP-Apt) bind to the PSMA protein expressed on the surface of LNCaP prostate epithelial cells and get taken up by these cells resulting in significantly enhanced in vitro cellular toxicity as compared with nontargeted nanoparticles that lack the PSMA aptamer (Dtxl-NP) (P < 0.0004). The Dtxl-NP-Apt bioconjugates also exhibit remarkable efficacy and reduced toxicity as measured by mean body weight loss (BWL) in vivo [body weight loss of 7.7 +/- 4% vs. 18 +/- 5% for Dtxl-NP-Apt vs. Dtxl-NP at nadir, respectively (mean +/- SD); n = 7]. After a single intratumoral injection of Dtxl-NP-Apt bioconjugates, complete tumor reduction was observed in five of seven LNCaP xenograft nude mice (initial tumor volume of approximately 300 mm3), and 100% of these animals survived our 109-day study. In contrast, two of seven mice in the Dtxl-NP group had complete tumor reduction with 109-day survivability of only 57%. Dtxl alone had a survivability of only 14%. Saline and nanoparticles without drug were similarly nonefficacious. This report demonstrates the potential utility of nanoparticle-aptamer bioconjugates for a therapeutic application.

Magnetically Responsive Polymeric Microparticles for Oral Delivery of Protein Drugs

PURPOSE

Protein drugs cannot be delivered efficiently through oral routes. To address this challenge, we evaluated the effect of prolonged gastrointestinal transit on the bioavailability of insulin carried by magnetically responsive microparticles in the presence of an external magnetic field.

METHODS

Magnetite nanocrystals and insulin were coencapsulated into poly(lactide-co-glycolide) (PLGA) microparticles and their effects on hypoglycemia were evaluated in mice in the presence of a circumferentially applied external magnetic field.

RESULTS

A single administration of 100 U/kg of insulin-magnetite-PLGA microparticles to fasted mice resulted in a reduction of blood glucose levels of up to 43.8% in the presence of an external magnetic field for 20 h (bioavailability = 2.77 +/- 0.46 and 0.87 +/- 0.29% based on glucose and ELISA assay, respectively), significantly higher than similarly dosed mice without a magnetic field (bioavailability = 0.66 +/- 0.56 and 0.30 +/- 0.06%, based on glucose and ELISA assay, respectively).

CONCLUSIONS

A substantially improved hypoglycemic effect was observed in mice that were orally administered with insulin-magnetite-PLGA microparticles in the presence of an external magnetic field, suggesting that magnetic force can be used to improve the efficiency of orally delivered protein therapeutics.

Collagen composite hydrogels for vocal fold lamina propria restoration

Chronic voice impairment due to scarring of the vocal fold (VF) lamina propria (LP) can be debilitating in terms of quality of life. Due to the dependence of normal VF vibration on proper VF geometry, an implant inserted to restore appropriate shape and pliability to scarred LP should ideally maintain its insertion-dimensions while being replaced by newly synthesized extracellular matrix (ECM). In the present study, collagen-alginate and collagen-hyaluronan (HA) composite hydrogels were investigated for their ability to support ECM synthesis by VF fibroblasts with limited hydrogel compaction and/or resorption. Collagen-HA composites showed significant mass loss over 28 days of culture, with little evidence of new matrix production. Collagen-alginate composites, in contrast, resisted scaffold compaction and mass loss for at least 42 days in culture while allowing for ECM synthesis. Collagen-alginate hydrogels appear to be promising materials for VF restoration, warranting further investigation.