Phase II trial of oxaliplatin and capecitabine after progression to first-line chemotherapy in androgen-independent prostate cancer patients

Prostate-specific antigen reduction after capecitabine plus oxaliplatin chemotherapy: A case report

BACKGROUND

Prostate cancer (PC) is currently the most common malignant tumor of the genitourinary system in men. Radical prostatectomy (RP) is recommended for the treatment of patients with localized PC. Adjuvant hormonal therapy (AHT) can be administered postoperatively in patients with high-risk or locally advanced PC. Chemotherapy is a vital remedy for castration-resistant prostate cancer (CRPC), and may also benefit patients with PC who have not progressed to CRPC.

CASE SUMMARY

A 68-year-old male was admitted to our hospital because of urinary irritation and dysuria with increased prostate-specific antigen (PSA) levels. After detailed examination, he was diagnosed with PC and treated with laparoscopic RP on August 3, 2020. AHT using androgen deprivation therapy (ADT) was performed postoperatively because of the positive surgical margin, extracapsular extension, and neural invasion but lasted only 6 mo. Unfortunately, he was diagnosed with rectal cancer about half a year after self-cessation of AHT, and was then treated with laparoscopic radical rectal resection and adjuvant chemotherapy using the capecitabine plus oxaliplatin (CapeOx) regimen. During the entire treatment process, the patient's PSA level first declined significantly after treatment of PC with laparoscopic RP and ADT, then rebounded because of self-cessation of ADT, and finally decreased again after CapeOx chemotherapy.

CONCLUSION

CapeOx chemotherapy can reduce PSA levels in patients with high-risk locally advanced PC, indicating that CapeOx may be an alternative chemotherapy regimen for PC.

Targeting E2F Sensitizes Prostate Cancer Cells to Drug-Induced Replication Stress by Promoting Unscheduled CDK1 Activity

Simple Summary

E2F1 and E2F2 are highly expressed in many cancer types, but their contribution to malignancy is not well understood. Here we aimed to define the impact of E2F1/E2F2 deregulation in prostate cancer. We show that inhibition of E2F sensitizes prostate cancer cells to drug-induced replication stress and cell death. We found that E2F target genes involved in nucleotide biosynthesis contribute to maintaining genome stability in prostate cancer cells, but their enzymatic activity is insufficient to prevent replication stress after E2F1/E2F2 depletion. Instead, E2F1/E2F2 hinder premature CDK1 activation during S phase, which is key to ensure genome stability and viability of prostate cancer cells. From a therapeutic perspective, inhibiting E2F activity provokes catastrophic levels of replication stress and blunts xenograft growth in combination with drugs targeting nucleotide biosynthesis or DNA repair. Our results highlight the suitability of targeting E2F for the treatment of prostate cancer.

Abstract

E2F1/E2F2 expression correlates with malignancy in prostate cancer (PCa), but its functional significance remains unresolved. To define the mechanisms governed by E2F in PCa, we analyzed the contribution of E2F target genes to the control of genome integrity, and the impact of modulating E2F activity on PCa progression. We show that silencing or inhibiting E2F1/E2F2 induces DNA damage during S phase and potentiates 5-FU-induced replication stress and cellular toxicity. Inhibition of E2F downregulates the expression of E2F targets involved in nucleotide biosynthesis (TK1, DCK, TYMS), whose expression is upregulated by 5-FU. However, their enzymatic products failed to rescue DNA damage of E2F1/E2F2 knockdown cells, suggesting additional mechanisms for E2F function. Interestingly, targeting E2F1/E2F2 in PCa cells reduced WEE1 expression and resulted in premature CDK1 activation during S phase. Inhibition of CDK1/CDK2 prevented DNA damage induced by E2F loss, suggesting that E2F1/E2F2 safeguard genome integrity by restraining CDK1/CDK2 activity. Importantly, combined inhibition of E2F and ATR boosted replication stress and dramatically reduced tumorigenic capacity of PCa cells in xenografts. Collectively, inhibition of E2F in combination with drugs targeting nucleotide biosynthesis or DNA repair is a promising strategy to provoke catastrophic levels of replication stress that could be applied to PCa treatment.

DNA-PKc inhibition overcomes taxane resistance by promoting taxane-induced DNA damage in prostate cancer cells

BACKGROUND

Overcoming taxane resistance remains a major clinical challenge in metastatic castrate-resistant prostate cancer (mCRPC). Loss of DNA repair proteins is associated with resistance to anti-microtubule agents. We propose that alterations in DNA damage response (DDR) pathway contribute to taxane resistance, and identification of these alterations may provide a potential therapeutic target to resensitize docetaxel-refractory mCRPC to taxane-based therapy.

METHODS

Alterations in DDR gene expression in our prostate cancer cell line model of docetaxel-resistance (DU145-DxR) derived from DU-145 cells were determined by DDR pathway-specific polymerase chain reaction array and immunoblotting. The PRKDC gene encoding DNA-PKc (DNA-dependent protein kinase catalytic unit), was noted to be overexpressed and evaluated for its role in docetaxel resistance. Cell viability and clonogenic survival of docetaxel-treated DU145-DxR cells were assessed after pharmacologic inhibition of DNA-PKc with three different inhibitors-NU7441, LTURM34, and M3814. Response to second-line cytotoxic agents, cabazitaxel and etoposide upon DNA-PKc inhibition was also tested. The impact of DNA-PKc upregulation on DNA damage repair was evaluated by comet assay and analysis of double-strand breaks marker, γH2AX and Rad51. Lastly, DNA-PKc inhibitor's effect on MDR1 activity was assessed by rhodamine 123 efflux assay.

RESULTS

DDR pathway-specific gene profiling revealed significant upregulation of PRKDC and CDK7, and downregulation of MSH3 in DU145-DxR cells. Compared to parental DU145, DU145-DxR cells sustained significantly less DNA damage when exposed to etoposide and docetaxel. Pharmacologic inhibition of DNA-PKc, a component of NHEJ repair machinery, with all three inhibitors, significantly resensitized DU145-DxR cells to docetaxel. Furthermore, DNA-PKc inhibition also resensitized DU145-DxR to cabazitaxel and etoposide, which demonstrated cross-resistance. Inhibition of DNA-PKc led to increased DNA damage in etoposide- and docetaxel-treated DU145-DxR cells. Finally, DNA-PKc inhibition did not affect MDR1 activity, indicating that DNA-PKc inhibitors resensitized taxane-resistant cells via an MDR1-independent mechanism.

CONCLUSION

This study supports a role of DDR genes, particularly, DNA-PKc in promoting resistance to taxanes in mCRPC. Targeting prostatic DNA-PKc may provide a novel strategy to restore taxane sensitivity in taxane-refractory mCRPC.

[Clinical efficacy of docetaxel combined with carboplatin in patients with metastatic castration-resistant prostate cancer]

OBJECTIVE

To observe the early efficacy and toxicity of docetaxel combined with carboplatin in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

From May 2017 to July 2019, fifteen patients with mCRPC treated in Peking University First Hospital were collected. The median age was 70 years (43-77 years), and the pathological types were all adenocarcinoma, which was confirmed as distant metastasis by imaging examination. They were given the chemotherapy of docetaxel combined with carboplatin. The specific method was as follows: each cycle was 28 days. Androgen deprivation therapy was administered routinely throughout the treatment period. Blood routine, liver and kidney function, blood clotting function and prostate-specific antigen (PSA) tests were performed before each cycle. Docetaxel was administered intravenously on the first day of each cycle at a dose of 75 mg/m², and carboplatin was administered intravenously on the second day at the dose calculated by Calvert formula. The main outcome measures including PSA decline range, pain remission rate and occurrence of adverse reactions were observed and analyzed.

RESULTS

Among the 15 patients, 12 had completed at least 4 cycles of chemotherapy and had short-term efficacy evaluation. PSA decline range > 50% was observed in 8 patients (66.7%). Among the 9 patients with bone pain, remarkable pain relief was observed in 4 patients (44.4%). Among the 4 patients with measurable metastatic lesions, 2 achieved partial response, 1 was evaluated as stable disease, and 1 was evaluated as progressive disease. The main adverse reactions of chemotherapy included bone marrow suppression, gastrointestinal reactions, fatigue and neurological disorders, and most of them were within the tolerable range.

CONCLUSION

This report is a case series study of docetaxel combined with carboplatin in the treatment of mCRPC reported in China and the conclusions are representative. The chemotherapy of docetaxel combined with carboplatin has positive short-term efficacy and high safety in patients with mCRPC, which is worthy of further promotion and exploration in clinical practice.

Effectiveness of Platinum-Based Chemotherapy in Patients With Metastatic Prostate Cancer: Systematic Review and Meta-analysis

BACKGROUND

Taxanes are the only cytotoxic drugs that have demonstrated a survival benefit for patients with castration-resistant prostate cancer (CRPC), but there is some evidence that platinum compounds may also benefit such patients.

METHODS

We performed a systematic search on electronic databases. We sought prospective clinical studies testing platinum compounds for CRPC. Platinum compounds could be delivered alone or in combination with other drugs. Both randomized and nonrandomized studies were included for qualitative synthesis, only randomized studies were included for meta-analyses. Clinical overall response rate (cORR), prostate-specific antigen overall response rate (sORR), progression-free survival (PFS), overall survival (OS), and toxicity were the outcomes of interest.

RESULTS

We identified 53 studies delivering platinum agents for patients with CRPC. cORR varied from 0 to 82%, while sORR varied from 2% to 100%. Response rates were higher in patients who received combination treatments rather than platinum compounds alone. Pooled data from randomized trials demonstrated a statistically significant increase in both cORR (odds ratio = 5.3; 95% confidence interval, 1.89-14.92) and sORR (odds ratio = 2.07; 95% confidence interval, 1.33-3.22) when adding platinum compounds to chemotherapy. PFS varied from 2.1 to 12 months and OS 4.2 to 28 months with platinum-containing chemotherapy. Nausea and myelosuppression were the most common adverse effects. Toxicity was manageable in most studies.

CONCLUSION

Platinum compounds are a safe and active treatment for CRPC. Response rates are higher when cytotoxic chemotherapy containing platinum agents are compared to nonplatinum chemotherapy. Data on OS and PFS are inconclusive. More research is needed to evaluate whether platinum-based chemotherapy results in a survival benefit for patients with CRPC, as well as to establish predictive biomarkers.

Early use of chemotherapy in metastatic prostate cancer

Since 2010, five new antineoplastic therapies have been FDA approved for the treatment of metastatic prostate cancer. With additional treatment options, questions arose about the optimal sequence of these agents. Until recently, chemotherapy has been deferred until later in the disease course in favor of next-generation androgen deprivation therapy. Prior to the development of abiraterone acetate and enzalutamide, clinical trials were opened investigating the combination of chemotherapy with androgen deprivation therapy in patients with metastatic hormone-sensitive disease. With the development of new oral therapies used to treat castration-resistant disease, these trials were largely forgotten or felt to be obsolete. Recently, two trials have been reported showing an overall survival benefit of the early use of chemotherapy in patients with hormone-naive prostate cancer, changing the treatment paradigm for metastatic disease. Here we review the history of chemotherapy in treating prostate cancer and the emerging evidence favoring its use as first-line therapy against metastatic hormone-sensitive disease.

Anti-tumour activity of platinum compounds in advanced prostate cancer-a systematic literature review

BACKGROUND

For men with advanced castration-resistant prostate cancer (CRPC), several treatment options are available, including androgen receptor (AR) pathway inhibitors (abiraterone acetate, enzalutamide), taxanes (docetaxel, cabazitaxel) and the radionuclide (radium-223). However, cross-resistance is a clinically relevant problem. Platinum compounds have been tested in a number of clinical trials in molecularly unselected prostate cancer patients. Advances in CRPC molecular profiling have shown that a significant proportion of patients harbour DNA repair defects, which may serve as predictive markers for sensitivity to platinum agents.

OBJECTIVE

To systematically identify and analyse clinical trials that have evaluated platinum agents in advanced prostate cancer patients.

METHODS

PubMed was searched to identify published clinical trials of platinum agents in advanced prostate cancer. The PRIMSA statement was followed for the systematic review process. Identified trials are analysed for study design, statistical plan, assessments of anti-tumour activity and the potential value of predictive biomarkers.

RESULTS

A total of 163 references were identified by the literature search and 72 publications that met the selection criteria were included in this review; of these 33 used carboplatin, 27 cisplatin, 6 satraplatin, 4 oxaliplatin and 2 other platinum compounds. Overall, anti-tumour activity varies in the range of 10%-40% for objective response and 20%-70% for PSA decline ≥50%. Response seemed highest for the combinations of carboplatin with taxanes or oxaliplatin with gemcitabine. The interpretation of the clinical data is limited by differences in response criteria used and patient populations studied.

CONCLUSION

Platinum compounds have moderate anti-tumour activity in molecularly unselected patients with advanced prostate cancer. Translational evidence of DNA repair deficiency should be leveraged in future studies to select prostate cancer patients most likely to benefit from platinum-based therapy.

Gemcitabine-oxaliplatin plus prednisolone is active in patients with castration-resistant prostate cancer for whom docetaxel-based chemotherapy failed

Background:

There has been no previous study on the activity of gemcitabine in combination with oxaliplatin (GemOx) for castration-resistant prostate cancer (CRPC).

Methods:

The GemOx was preclinically tested for cytotoxic activity in human prostate cancer cell lines. Clinically, patients with CRPC who failed prior docetaxel were treated with gemcitabine 1000 mg m⁻² and oxaliplatin 100 mg m⁻² intravenously every 2 weeks and prednisolone 5 mg orally twice daily. The primary end point was the prostate-specific antigen (PSA) response rate.

Results:

The GemOx displayed synergistic effects based on Chou and Talalay analysis. In the phase II study, 33 patients were accrued. The median dose of docetaxel exposure was 518 mg m⁻². A total of 270 cycles were administered with a median of eight cycles per patient. A PSA response rate was 55% (95% CI, 38–72) and radiologic response rate was 82% (9 out of 11). With a median follow-up duration of 20.5 months, the median time to PSA progression was 5.8 months (95% CI, 4.4–7.2) and the median overall survival was 17.6 months (95% CI, 12.6–22.6). The most frequently observed grade 3 or 4 toxicities were neutropenia (13%) and thrombocytopenia (13%).

Conclusions:

The GemOx is active and tolerable in patients with metastatic CRPC after docetaxel failure (NCT 01487720).

Recent progress in pharmaceutical therapies for castration-resistant prostate cancer

Since 2010, six drugs have been approved for the treatment of castration-resistant prostate cancer, i.e., CYP17 inhibitor Abiraterone, androgen receptor antagonist Enzalutamide, cytotoxic agent Cabazitaxel, vaccine Sipuleucel-T, antibody Denosumab against receptor activator of nuclear factor kappa B ligand and radiopharmaceutical Alpharadin. All these drugs demonstrate improvement on overall survival, expect for Denosumab, which increases the bone mineral density of patients under androgen deprivation therapy and prolongs bone-metastasis-free survival. Besides further CYP17 inhibitors (Orteronel, Galeterone, VT-464 and CFG920), androgen receptor antagonists (ARN-509, ODM-201, AZD-3514 and EZN-4176) and vaccine Prostvac, more drug candidates with various mechanisms or new indications of launched drugs are currently under evaluation in different stages of clinical trials, including various kinase inhibitors and platinum complexes. Some novel strategies have also been proposed aimed at further potentiation of antitumor effects or reduction of side effects and complications related to treatments. Under these flourishing circumstances, more investigations should be performed on the optimal combination or the sequence of treatments needed to delay or reverse possible resistance and thus maximize the clinical benefits for the patients.

Gene expression signature predicting high-grade prostate cancer responses to oxaliplatin

Prostate cancer is one of the leading causes of cancer-related deaths among men. Several prognostic factors allow differentiation of low-grade tumors from high-grade tumors with high metastatic potential. High-grade tumors are currently treated with hormone therapy, to which taxanes are added when the tumors become resistant to castration. Clinical trials with other anticancer agents did not take into account the genetic backgrounds of the tumors, and most trials demonstrated low response rates. Here we used an in silico approach to screen for drug candidates that might be used as alternatives to taxanes, on the basis of a published expression signature involving 86 genes that could distinguish high-grade and low-grade tumors (Proc Natl Acad Sci USA 103:10991-10996, 2006). We explored the National Cancer Institute databases, which include data on the gene expression profiles of 60 human tumor cell lines and the in vitro sensitivities of the cell lines to anticancer drugs, and we identified several genes in the signature for which expression levels were correlated with chemosensitivity. As an example of the validation of this in silico approach, we identified a set of six genes for which expression levels could predict cell sensitivity to oxaliplatin but not cisplatin. This signature was validated in vitro through silencing of the genes in DU145, LNCaP, and C4-2B prostate cancer cells, which was accompanied by changes in oxaliplatin but not cisplatin cytotoxicity. These results demonstrate the relevance of our approach for the identification of both alternative treatments for high-grade prostate cancers and new biomarkers to predict clinical tumor responses.

Constitutive and treatment-induced CXCL8-signalling selectively modulates the efficacy of anti-metabolite therapeutics in metastatic prostate cancer

BACKGROUND

The current study was undertaken to characterize the effect of anti-metabolites on inducing CXCL8 signaling and determining whether the constitutive and/or drug-induced CXCL8 signaling in metastatic prostate cancer (CaP) cells modulates their sensitivity to this class of agent.

METHODS

The response of metastatic CaP cells to 5-Fluorouracil (5-FU), Pemetrexed or Tomudex was determined using cell count assays, flow cytometry and PARP cleavage analysis. Quantitative-PCR, ELISA and immunoblots were employed to determine effects of drugs or CXCL8 administration on target gene/protein expression.

RESULTS

Administration of 5-FU but not pemetrexed potentiated CXCL8 secretion and increased CXCR1 and CXCR2 gene expression in metastatic PC3 cells. Consistent with this, the inhibition of CXCL8 signaling using a CXCR2 antagonist, AZ10397767, increased the cytotoxicity of 5-FU by 4-fold (P<0.001), and increased 5-FU-induced apoptosis in PC3 cells (P<0.01). In contrast, while administration of AZ10397767 had no effect on the sensitivity of pemetrexed, the CXCR2 antagonist exerted the greatest effect in increasing the sensitivity of PC3 cells to Tomudex, a directed thymidylate synthase (TS) inhibitor. Subsequent experiments confirmed that administration of recombinant human CXCL8 increased TS expression, a response mediated in part by the CXCR2 receptor. Moreover, siRNA-mediated knockdown of the CXCL8-target gene Bcl-2 increased the sensitivity of PC3 cells to 5-FU.

CONCLUSIONS

CXCL8 signaling provides a selective resistance of metastatic prostate cancer cells to specific anti-metabolites by promoting a target-associated resistance, in addition to underpinning an evasion of treatment-induced apoptosis.

Evaluation of oral chemotherapy with capecitabine and cyclophosphamide plus thalidomide and prednisone in prostate cancer patients

PURPOSE

The aim of this study was to evaluate clinical outcomes of second-line chemotherapy with capecitabine and cyclophosphamide (CTX) plus thalidomide and prednisone in refractory advanced castrate-resistant prostate cancer (CRPC) patients.

METHODS

We retrospectively reviewed patients with advanced CRPC who had previously progressed to first-line docetaxel-based chemotherapy. Patients were given second-line chemotherapy with capecitabine and CTX plus thalidomide and prednisone throughout the course. Patients were evaluated for response and toxicity, and treatment was continued until the disease progression or excessive toxicity was noted.

RESULTS

From April 2007 to February 2010, a total of 28 patients (median age, 72.8 ± 2.9 years) received second-line chemotherapy. The median cycle and duration of metronomic chemotherapy were six (range: 1-12) cycles and 6.3 (range 1.5-20.5) months, respectively. Prostatic-specific antigen was decreased by more than 50% in 10 (35.7%) of the 28 patients. All patients had bone metastases, and 8 patients (28.6%) had measurable soft tissue lesions. Among the 8 patients, 1 patient achieved partial response, and 3 patients had stabilized disease. With a median follow-up time of 29.5 (95% CI, 26.4-33.4) months, median composite progression-free survival and overall survival were 4.7 (95% CI, 3.4-5.7) months and 19.5 (95% CI, 18.9-25.5) months, respectively. No grade 3-4 toxicity was observed, and none of the patients experienced grade 3-4 hematological and nonhematological toxicities.

CONCLUSIONS

These data suggested that oral combination second-line chemotherapy with capecitabine and CTX plus thalidomide and prednisone offers promising activity with an excellent safety profile for patients with advanced CRPC.

Evolving standards in the treatment of docetaxel-refractory castration-resistant prostate cancer

The management of men with metastatic castration-resistant prostate cancer (CRPC) has taken several leaps forward in the past year, with the demonstration of improved overall survival with three novel agents (sipuleucel-T, cabazitaxel with prednisone and abiraterone acetate with prednisone), and a significant delay in skeletal-related events observed with denosumab. The pipeline of systemic therapies in prostate cancer remains strong, as multiple agents with a diverse array of mechanisms of action are showing preliminary signs of clinical benefit, leading to more definitive phase III confirmatory trials. In this review, which represents part 1 of a two-part series on metastatic CRPC, we will summarize the mechanisms of resistance to hormonal and chemotherapies and discuss the evolving landscape of treatment options for men with CRPC, with a particular focus on currently approved and emerging treatment options following docetaxel administration, as well as prognostic factors in this post-docetaxel state. As docetaxel remains the standard initial systemic therapy for men with metastatic CRPC for both palliative and life-prolonging purposes, knowledge of these evolving standards will help to optimize delivery of care and long-term outcomes.

Second-line chemotherapy in metastatic docetaxel-resistant prostate cancer: a review

The results of cytotoxic therapy in the second-line setting of metastatic castration-resistant prostate cancer have demonstrated that disease is poorly controlled after taxane resistance with a time to progression of 3 months or less. Many trials of second-line chemotherapy have been disappointing. However, most of patients with docetaxel-pretreated castration-resistant disease receive a second-line chemotherapy. Molecular mechanism of castration resistance and docetaxel resistance is resumed, and clinical trials of second-line chemotherapy after docetaxel progression are reviewed. Reintroduction of docetaxel after a drug-free interval is an active treatment in docetaxel-pretreated patients, and only recently a prospective study documented a survival benefit of 2.4 months after second-line taxane-based chemotherapy of metastatic docetaxel-resistant prostate cancer. Although a second-line chemotherapy with a taxane could improve overall survival, a change of biology of castration-resistant prostate cancer after docetaxel is suggested, as inferred by the renewed hormonal sensitivity, whose role on survival remains unknown, and from the activity of antiangiogenic drugs.