Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model

Kinesin Facilitates Phenotypic Targeting of Therapeutic Resistance in Advanced Prostate Cancer

Understanding the mechanisms underlying resistance is critical to improving therapeutic outcomes in patients with metastatic castration-resistant prostate cancer. Previous work showed that dynamic interconversions between epithelial-mesenchymal transition to mesenchymal-epithelial transition defines the phenotypic landscape of prostate tumors, as a potential driver of the emergence of therapeutic resistance. In this study, we use in vitro and in vivo preclinical MDA PCa patient-derived xenograft models of resistant human prostate cancer to determine molecular mechanisms of cross-resistance between antiandrogen therapy and taxane chemotherapy, underlying the therapeutically resistant phenotype. Transcriptomic profiling revealed that resistant and sensitive prostate cancer C4-2B cells have a unique differential gene signature response to cabazitaxel. Gene pathway analysis showed that sensitive cells exhibit an increase in DNA damage, while resistant cells express genes associated with protein regulation in response to cabazitaxel. The patient-derived xenograft model specimens are from patients who have metastatic lethal castration-resistant prostate cancer, treated with androgen deprivation therapy, antiandrogens, and chemotherapy including second-line taxane chemotherapy, cabazitaxel. Immunohistochemistry revealed high expression of E-cadherin and low expression of vimentin resulting in redifferentiation toward an epithelial phenotype. Furthermore, the mitotic kinesin-related protein involved in microtubule binding and the SLCO1B3 transporter (implicated in cabazitaxel intracellular transport) are associated with resistance in these prostate tumors. Combinational targeting of kinesins (ispinesib) with cabazitaxel was more effective than single monotherapies in inducing cell death in resistant prostate tumors. Implications: Our findings are of translational significance in identifying kinesin as a novel target of cross-resistance toward enhancing therapeutic vulnerability and improved clinical outcomes in patients with advanced prostate cancer.

Glymphatic function and its influencing factors in different glucose metabolism states

BACKGROUND

Dysfunction of the glymphatic system in the brain in different stages of altered glucose metabolism and its influencing factors are not well characterized.

AIM

To investigate the function of the glymphatic system and its clinical correlates in patients with different glucose metabolism states, the present study employed diffusion tensor imaging along the perivascular space (DTI-ALPS) index.

METHODS

Sample size was calculated using the pwr package in R software. This cross-sectional study enrolled 22 patients with normal glucose metabolism (NGM), 20 patients with prediabetes, and 22 patients with type 2 diabetes mellitus (T2DM). A 3.0T magnetic resonance imaging was used to evaluate the function of the glymphatic system. The mini-mental state examination (MMSE) was used to assess general cognitive function. The DTI-ALPS index of bilateral basal ganglia and the mean DTI-ALPS index was calculated. Further, the correlation between DTI-ALPS and clinical features was assessed.

RESULTS

The left-side, right-side, and mean DTI-ALPS index in the T2DM group were significantly lower than that in the NGM group. The right-side DTI-ALPS and mean DTI-ALPS index in the T2DM group were significantly lower than those in the prediabetes group. DTI-ALPS index lateralization was not observed. The MMSE score in the T2DM group was significantly lower than that in the NGM and prediabetes group. After controlling for sex, the left-side DTI-ALPS and mean DTI-ALPS index in the prediabetes group were positively correlated with 2-hour postprandial blood glucose level; the left-side DTI-ALPS index was negatively correlated with total cholesterol and low-density lipoprotein level. The right-side DTI-ALPS and mean DTI-ALPS index were negatively correlated with the glycosylated hemoglobin level and waist-to-hip ratio in the prediabetes group. The left-side, right-side, and mean DTI-ALPS index in the T2DM group were positively correlated with height. The left-side and mean DTI-ALPS index in the T2DM group were negatively correlated with high-density lipoprotein levels.

CONCLUSION

Cerebral glymphatic system dysfunction may mainly occur in the T2DM stage. Various clinical variables were found to affect the DTI-ALPS index in different glucose metabolism states. This study enhances our understanding of the pathophysiology of diabetic brain damage and provides some potential biological evidence for its early diagnosis.

Patient-Derived Xenografts and Organoids Recapitulate Castration-Resistant Prostate Cancer with Sustained Androgen Receptor Signaling

Castration-resistant prostate cancer (CRPC) remains an incurable and lethal malignancy. The development of new CRPC treatment strategies is strongly impeded by the scarcity of representative, scalable and transferable preclinical models of advanced, androgen receptor (AR)-driven CRPC. Here, we present contemporary patient-derived xenografts (PDXs) and matching PDX-derived organoids (PDXOs) from CRPC patients who had undergone multiple lines of treatment. These models were comprehensively profiled at the morphologic, genomic (n = 8) and transcriptomic levels (n = 81). All are high-grade adenocarcinomas that exhibit copy number alterations and transcriptomic features representative of CRPC patient cohorts. We identified losses of PTEN and RB1, MYC amplifications, as well as genomic alterations in TP53 and in members of clinically actionable pathways such as AR, PI3K and DNA repair pathways. Importantly, the clinically observed continued reliance of CRPC tumors on AR signaling is preserved across the entire set of models, with AR amplification identified in four PDXs. We demonstrate that PDXs and PDXOs faithfully reflect donor tumors and mimic matching patient drug responses. In particular, our models predicted patient responses to subsequent treatments and captured sensitivities to previously received therapies. Collectively, these PDX-PDXO pairs constitute a reliable new resource for in-depth studies of treatment-induced, AR-driven resistance mechanisms. Moreover, PDXOs can be leveraged for large-scale tumor-specific drug response profiling critical for accelerating therapeutic advances in CRPC.

Administering Docetaxel for Metastatic Hormone-Sensitive Prostate Cancer 1-6 Days Compared to More Than 14 Days after the Start of LHRH Agonist Is Associated with Better Clinical Outcomes Due to Androgen Flare

Simple Summary

Hormonal therapy with long-acting luteinizing hormone-releasing hormone (LHRH) for metastatic hormone-sensitive prostate cancer (MHSPC) results initially in testosterone flare followed by testosterone deprivation. Docetaxel is a chemotherapy that is effective against prostate cancer and specifically targets cells during cell division by stabilizing the mitotic spindle, which results in “mitotic catastrophe” and death of the dividing cancer cells. Combining LHRH and docetaxel was proved to be superior to LHRH treatment alone. Here, we show that simply by providing the first dose of docetaxel during testosterone flare, which occurs 1–6 days after LHRH initiation, patients could have better clinical outcomes, as testosterone drives specifically prostate cells into mitosis, priming them to cell kill by docetaxel.

Abstract

Docetaxel, when given at the beginning of androgen deprivation therapy (ADT) for patients with metastatic hormone-sensitive prostate cancer (MHSPC), results in significantly longer overall survival than ADT alone. We aimed to investigate if the delivery of the first dose of docetaxel during the testosterone flare associated with LHRH initiation results in better clinical outcomes, as testosterone induces mitosis of prostate cancer cells, and docetaxel specifically targets cells in mitosis. We analyzed data from the CHAARTED trial which randomized MHSPC patients to ADT alone or ADT plus docetaxel. We included only patients treated with LHRH agonist and docetaxel (n = 379). The only cutoff that resulted in differences in treatment outcomes was between patients who started docetaxel 1–6 days (n = 18) compared to more than 14 days from LHRH initiation (n = 297). Actuarial median overall survival was 72 versus 57 months (p = 0.2); progression-free survival was 49 versus 17 months (p = 0.06), and freedom from castrate-resistant prostate cancer was 51 versus 18 months (p = 0.04) for patients who started docetaxel 1–6 days compared to more than 14 days from LHRH initiation, respectively. Administering docetaxel 1–6 days from the initiation of LHRH agonist for patients with MHSPC could be associated with improved clinical outcomes.

Continued Androgen Signalling Inhibition improves Cabazitaxel Efficacy in Prostate Cancer

BACKGROUND

The androgen receptor (AR) pathway is a key driver of neoplastic behaviour in the different stages of metastatic prostate cancer (mPCa). Targeting the AR therefore remains the cornerstone for mPCa treatment. We have previously reported that activation of AR signalling affects taxane chemo-sensitivity in preclinical models of castration resistant PCa (CRPC). Here, we explored the anti-tumour efficacy of the AR targeted inhibitor enzalutamide combined with cabazitaxel.

METHODS

We used the AR positive CRPC model PC346C-DCC-K to assess the in vitro and in vivo activity of combining enzalutamide with cabazitaxel. Subsequent validation studies were performed using an enzalutamide resistant VCaP model. To investigate the impact of AR signalling on cabazitaxel activity we used quantitative live-cell imaging of tubulin stabilization and apoptosis related nuclear fragmentation.

FINDINGS

Enzalutamide strongly amplified cabazitaxel anti-tumour activity in the patient-derived xenograft models PC346C-DCC-K (median time to humane endpoint 77 versus 48 days, P<0.0001) and VCaP-Enza-B (median time to humane endpoint 80 versus 53 days, P<0.001). Although enzalutamide treatment by itself was ineffective in reducing tumour growth, it significantly suppressed AR signalling in PC346C-DCC-K tumours as shown by AR target gene expression. The addition of enzalutamide enhanced cabazitaxel induced apoptosis as shown by live-cell imaging (P<0.001).

INTERPRETATION

Our study demonstrates that cabazitaxel efficacy can be improved by simultaneous blocking of AR signalling by enzalutamide, even if AR targeted treatment no longer affects tumour growth. These findings support clinical studies that combine AR targeted inhibitors with cabazitaxel in CRPC.

Prognostic Value of High-Sensitivity Modified Glasgow Prognostic Score in Castration-Resistant Prostate Cancer Patients Who Received Docetaxel

Simple Summary

Prostate cancer is one of the most prevalent cancers in men. Prostate cancer is characterized by an early response to hormonal therapy and prostate-specific antigen (PSA) is useful for diagnosis, prognosis, and treatment evaluation. However, if the patient becomes resistant to treat and develops castration-resistant prostate cancer (CRPC), it is difficult to predict prognosis and evaluate response to treatment using PSA alone. In this study, we found that the high-sensitivity modified Glasgow prognostic score (Hs-mGPS), an inflammatory response score, is a more powerful prognostic factor for CRPC than the modified Glasgow prognostic score (mGPS) previously studied. Furthermore, we suggest that risk classification using Hs-mGPS, PSA, and testosterone (TST) may be a useful tool to predict the prognosis of late staged CRPC.

Abstract

The Glasgow prognostic score, a marker of systemic inflammation, is associated with clinical outcomes in different cancers including prostate cancer. However, there is no evidence for the relationship between the high-sensitivity modified Glasgow prognostic score (Hs-mGPS) in prostate cancer and its prognosis. This study aimed to investigate the prognostic significance of Hs-mGPS in castration-resistant prostate cancer (CRPC) treated with docetaxel. We retrospectively analyzed clinical datasets from 131 CRPC patients who received docetaxel treatment at Chiba University Hospital and a related hospital. Clinical factors including Hs-mGPS before docetaxel treatment were evaluated according to overall survival. The numbers of patients with Hs-mGPS of 0, 1, and 2 were 88, 30, and 13, respectively. The median prostate-specific antigen (PSA) level was 28.9 ng/mL. The median testosterone level was 13.0 ng/dL. The percentages of bone and visceral metastases were 80.8% and 10.2%, respectively. For overall survival, Hs-mGPS ≥ 1 (hazard ratio of 2.41; p = 0.0048), testosterone ≥ 13.0 ng/dL (hazard ratio of 2.23; p = 0.0117), and PSA ≥ 28.9 ng/mL (hazard ratio of 2.36; p = 0.0097) were significant poor prognostic factors in the multivariate analysis. The results of the two-group analysis showed that a higher Hs-mGPS was associated with high PSA, alkaline phosphatase, and testosterone levels. The median testosterone levels for Hs-mGPS of 0, 1, and 2 were 9.0, 16.5, and 23.0, respectively. Based on the multivariate analysis, we created a combined score with three prognostic factors: Hs-mGPS, testosterone, and PSA. The low-risk group (score of 0–1) showed a significantly longer overall survival compared to the intermediate-risk (score of 2–3) and high-risk (score of 4) groups (p < 0.0001). Our results demonstrated that an elevated Hs-mGPS was an independent prognostic factor in CRPC patients treated with docetaxel therapy. Risk classification based on Hs-mGPS, testosterone, and PSA may be useful in predicting the prognosis of CRPC patients.

[18F]-JK-PSMA-7 and [18F]-FDG tumour PET uptake in treated xenograft human prostate cancer model in mice

PURPOSE

This preclinical study aims to evaluate the extent to which a change in prostate-specific membrane antigen (PSMA) expression of castration-resistant prostate cancer (CRPC) following standard treatment is reflected in [¹⁸F]JK-PSMA-7 PET/CT.

METHODS

Castrated mice supplemented with testosterone implant were xenografted with human LNCaP CRPC. After appropriate tumour growth, androgen deprivation therapy (ADT) was carried out by the removal of the implant followed by a single injection of docetaxel (400 μg/20-g mouse) 2 weeks later. [¹⁸F]JK-PSMA-7 PET/CT were performed before ADT, then before and at days 12, 26, 47 and 69 after docetaxel administration. The [¹⁸F]JK-PSMA-7 PET data were compared to corresponding unspecific metabolic [¹⁸F]FDG PET/CT and ex vivo quantification of PSMA expression estimated by flow cytometry on repeated tumour biopsies.

RESULTS

ADT alone had no early effect on LNCaP tumours that pursued their progression. Until day 12 post-docetaxel, the [¹⁸F]JK-PSMA7 uptake was significantly higher than that of [¹⁸F]FDG, indicating the persistence of PSMA expression at those time points. From day 26 onwards when the tumours were rapidly expanding, both [¹⁸F]JK-PSMA7 and [¹⁸F]FDG uptake continuously decreased although the decrease in [¹⁸F]JK-PSMA uptake was markedly faster. The fraction of PSMA-positive cells in tumour biopsies decreased similarly over time to reach a non-specific level after the same time period.

CONCLUSION

Applying PSMA-based imaging for therapy monitoring in patients with CRPC should be considered with caution since a reduction in [¹⁸F]JK-PSMA-7 PET uptake after successive ADT and chemotherapy may be related to downregulation of PSMA expression in dedifferentiated and rapidly proliferating tumour cells.

Molecular tracing of prostate cancer lethality

Prostate cancer is diagnosed mostly in men over the age of 50 years, and has favorable 5-year survival rates due to early cancer detection and availability of curative surgical management. However, progression to metastasis and emergence of therapeutic resistance are responsible for the majority of prostate cancer mortalities. Recent advancement in sequencing technologies and computational capabilities have improved the ability to organize and analyze large data, thus enabling the identification of novel biomarkers for survival, metastatic progression and patient prognosis. Large-scale sequencing studies have also uncovered genetic and epigenetic signatures associated with prostate cancer molecular subtypes, supporting the development of personalized targeted-therapies. However, the current state of mainstream prostate cancer management does not take full advantage of the personalized diagnostic and treatment modalities available. This review focuses on interrogating biomarkers of prostate cancer progression, including gene signatures that correspond to the acquisition of tumor lethality and those of predictive and prognostic value in progression to advanced disease, and suggest how we can use our knowledge of biomarkers and molecular subtypes to improve patient treatment and survival outcomes.

Androgen receptor signalling impairs docetaxel efficacy in castration-resistant prostate cancer

Androgen receptor (AR) signalling drives neoplastic growth and therapy resistance in prostate cancer. Recent clinical data show that docetaxel combined with androgen deprivation therapy improves outcome in hormone-sensitive disease. We studied whether testosterone and AR signalling interferes with docetaxel treatment efficacy in castration-resistant prostate cancer (CRPC). We found that testosterone supplementation significantly impaired docetaxel tumour accumulation in a CRPC model, resulting in decreased tubulin stabilisation and antitumour activity. Furthermore, testosterone competed with docetaxel for uptake by the drug transporter OATP1B3. Irrespective of docetaxel-induced tubulin stabilisation, AR signalling by testosterone counteracted docetaxel efficacy. AR-pathway activation could also reverse long-term tumour regression by docetaxel treatment in vivo. These results indicate that to optimise docetaxel efficacy, androgen levels and AR signalling need to be suppressed. This study lends evidence for continued maximum suppression of AR signalling by combining targeted therapeutics with docetaxel in CRPC.

Androgens modify therapeutic response to cabazitaxel in models of advanced prostate cancer

BACKGROUND

Disruption of the phenotypic landscape via epithelial-mesenchymal transition (EMT) enables prostate cancer cells to metastasize and acquire therapeutic resistance. Our previous studies demonstrated that cabazitaxel (CBZ) (second-generation Food and Drug Administration-approved taxane chemotherapy), used for the treatment of castration-resistant prostate cancer (CRPC), causes reversal of EMT to mesenchymal-epithelial transition (MET) and reduces expression of kinesin motor protein KIFC1 (HSET). The present study examined the effect of sequencing CBZ chemotherapy mediated MET on prostate tumor redifferentiation overcoming therapeutic resistance in models of advanced prostate cancer.

METHODS

To examine the impact of androgens on the antitumor effect of CBZ, we used human prostate cancer cell lines with different sensitivity to androgens and CBZ, in vitro, and two human prostate cancer xenograft models in vivo. Tumor-bearing male mice (with either the androgen-sensitive LNCaP or the CRPC 22Rv1 xenografts) were treated with CBZ (3 mg/kg) alone, or in combination with castration-induced androgen-deprivation therapy (ADT) for 14 days.

RESULTS

Cell viability assays indicate that the presence of 5α-dihydrotestosterone (1 nM) confers resistance to CBZ in vitro. CBZ treatment in vivo induced MET in LNCaP-derived tumors as shown by increased E-cadherin and decreased N-cadherin levels. Sequencing CBZ after ADT improves tumor response in androgen-sensitive LNCaP, but not in CRPC 22Rv1 xenografts. Mechanistic dissection revealed a novel association between the androgen receptor and HSET in prostate cancer cells that is inhibited by CBZ in an androgen-dependent manner.

CONCLUSIONS

Our findings provide new insights into the phenotypic reprogramming of prostate cancer cells to resensitize tumors to CBZ action. This evidence is of translational significance in treatment sequencing (CBZ and ADT) towards improved therapeutic benefit in patients with lethal CRPC.

Higher serum testosterone levels predict poor prognosis in castration-resistant prostate cancer patients treated with docetaxel

BACKGROUND

The role of testosterone as a prognostic factor for castration-resistant prostate cancer treated with docetaxel in Japan was investigated.

METHODS

A total of 164 patients with castration-resistant prostate cancer who received docetaxel treatment at Chiba University Hospital and an affiliated hospital were retrospectively analyzed. Testosterone and other clinical factors at the start of docetaxel treatment were evaluated with respect to overall survival and progression-free survival.

RESULTS

Of the 164 patients, 69 had high-volume tumors. The median prostatic-specific antigen was 27.0 ng/mL. The median testosterone was 13.0 ng/dL. The rates of bone and visceral metastases were 80.1% and 8.8%, respectively. For progression-free survival, testosterone ≥13 ng/dL was an independent prognostic factor only on univariate analysis (hazard ratio, 1.81; P = .0108). For overall survival, testosterone ≥ 1.3 ng/dL (hazard ratio, 3.37; P < .0001), high volume (hazard ratio, 3.06; P = .0009), and prostate-specific antigen ≥ 27.0 ng/mL (hazard ratio, 2.75; P = .0013) were independent prognostic factors on multivariate analysis. When assessing related clinical factors, higher serum testosterone was associated with visceral metastasis, high volume, and prostate-specific antigen. Based on three prognostic factors (testosterone, high volume, prostate-specific antigen), a risk classification was developed. The high-risk group (3 risk factors) showed a significantly shorter overall survival compared to the moderate-risk (2 risk factors) and low-risk (0-1 risk factor) groups (P < .0001).

CONCLUSIONS

The present study identified higher serum testosterone (≥13 ng/dL) as a significant prognostic factor in castration-resistant prostate cancer patients treated with docetaxel therapy.

Association of prostate cancer SLCO gene expression with Gleason grade and alterations following androgen deprivation therapy

Background.

SLCO-encoded transporters have been associated with progression to castration resistant prostate cancer (CRPC) after initiation of androgen deprivation therapy (ADT). Although expressed at lower levels than in CRPC tissues, SLCO-encoded transporters may also play a role in response of primary prostate cancer (PCa) to ADT and biochemical recurrence.

Methods.

We systematically explored expression of the 11 human SLCO genes in a large sample of untreated and ADT-treated normal prostate (NP) and primary PCa tissues, including tumors treated with neoadjuvant abiraterone.

Results.

Transporters with the most recognized role in steroid uptake in PCa, including SLCO2B1 (DHEAS) and 1B3 (testosterone), were consistently detected in primary PCa. SLCO1B3 was nearly 5-fold higher in PCa vs NP with no difference in Gleason 3 vs 4 and no change with ADT. SLCO2B1 was detected at 3-fold lower levels in PCa than NP but was nearly 7-fold higher in Gleason 4 vs Gleason 3 and increased 3-fold following ADT (p<0.05 for all).

Conclusions.

We observed clear differences in SLCO expression in PCa vs NP samples, in Gleason 4 vs Gleason 3 tumors, and in ADT-treated vs untreated tissues. These findings are hypothesis generating due to small sample size, but suggest that baseline and ADT-induced changes in PCa OATP expression may influence steroid uptake and response to ADT, as well as uptake and response to drugs such as abiraterone and docetaxel which are also subject to OATP-mediated transport and are now being routinely combined with ADT in the metastatic castration sensitive setting.

Serum testosterone level as possible predictive marker in androgen receptor axis-targeting agents and taxane chemotherapies for castration-resistant prostate cancer

PURPOSE

Currently, several therapeutic options for castration-resistant prostate cancer (CRPC) are available, for which predictive biomarkers have not been established. Therefore, we aimed to reveal the association between pretreatment serum testosterone level and antitumor outcomes when treated with androgen receptor axis-targeting agents and taxane chemotherapies for CRPC.

PATIENTS AND METHODS

The present study included Japanese patients with metastatic prostate cancer whose serum testosterone levels during androgen-deprivation therapy were available. The antitumor outcomes when treated with enzalutamide, abiraterone, docetaxel, and cabazitaxel with clinicopathological parameters including serum testosterone levels during androgen-deprivation therapy, as well as prognoses including progression-free survival and overall survival, were examined.

RESULTS

Progression-free survival among men with higher serum testosterone level was superior to that among men with lower serum testosterone level when treated with enzalutamide. On the contrary, progression-free survival and overall survival among men with higher serum testosterone level were significantly inferior to those among men with lower serum testosterone level when treated with docetaxel and cabazitaxel, respectively.

CONCLUSIONS

The present study indicated distinct prognostic values of serum testosterone level when treated with androgen receptor axis-targeting agent and taxane chemotherapy for CRPC, suggesting that serum testosterone level may be useful predictive biomarker to navigate the appropriate therapy in patients with CRPC.