Phase II study of vinorelbine with low dose prednisone in the treatment of hormone-refractory metastatic prostate cancer

Metronomic Chemotherapy in Prostate Cancer

Despite the significant expansion of the therapeutic armamentarium associated with the introduction of novel endocrine therapies, cytotoxic agents, radiopharmaceuticals, and PARP inhibitors, progression of metastatic castration-resistant prostate cancer (mCRPC) beyond treatment options remains the leading cause of death in advanced prostate cancer patients. Metronomic chemotherapy (MC) is an old concept of wise utilization of cytotoxic agents administered continuously and at low doses. The metronomic is unique due to its multidimensional mechanisms of action involving: (i) inhibition of cancer cell proliferation, (ii) inhibition of angiogenesis, (iii) mitigation of tumor-related immunosuppression, (iv) impairment of cancer stem cell functions, and (v) modulation of tumor and host microbiome. MC has been extensively studied in advanced prostate cancer before the advent of novel therapies, and its actual activity in contemporary, heavily pretreated mCRPC patients is unknown. We have conducted a prospective analysis of consecutive cases of mCRPC patients who failed all available standard therapies to find the optimal MC regimen for phase II studies. The metronomic combination of weekly paclitaxel 60 mg/m² i.v. with capecitabine 1500 mg/d p.o. and cyclophosphamide 50 mg/d p.o. was selected as the preferred regimen for a planned phase II study in heavily pretreated mCRPC patients.

CCNB1 and AURKA are critical genes for prostate cancer progression and castration-resistant prostate cancer resistant to vinblastine

BACKGROUND

Prostate cancer (PCa) is a common malignancy occurring in men. As both an endocrine and gonadal organ, prostate is closely correlated with androgen. So, androgen deprivation therapy (ADT) is effective for treating PCa. However, patients will develop castration-resistant prostate cancer (CRPC) stage after ADT. Many other treatments for CRPC exist, including chemotherapy. Vinblastine, a chemotherapeutic drug, is used to treat CRPC. However, patients will develop resistance to vinblastine. Genetic alterations have been speculated to play a critical role in CRPC resistance to vinblastine; however, its mechanism remains unclear.

METHODS

Various databases, such as Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA) and Chinese Prostate Cancer Genome and Epigenome Atlas (CPGEA), were used to collect the RNA-sequence data of PCa and CRPC patients and vinblastine-resistant PCa cells. Using online tools, Metascape and TIMER, the pathways and immune infiltration associated with vinblastine resistance-related genes in PCa were analyzed. The function of these genes was verified in clinical samples and CRPC cells.

RESULTS

Using GSE81277 dataset, we collected the RNA-sequence data of vinblastine sensitive and resistant LNCaP cells and found nine genes (CDC20, LRRFIP1, CCNB1, GPSM2, AURKA, EBLN2, CCDC150, CENPA and TROAP) that correlated with vinblastine resistance. Furthermore, CCNB1, GPSM2 and AURKA were differently expressed between normal prostate and PCa tissues, even influencing PCa progression. The GSE35988 dataset revealed that CCNB1 and AURKA were upregulated in PCa and CRPC samples. Various genes were also found to affect the survival status of PCa patients based on TCGA. These genes were also related to immune cell infiltration. Finally, we verified the function of CCNB1 and AURKA and observed that they were upregulated in PCa and CRPC clinical samples and increased the sensitivity of CRPC cells to vinblastine.

CONCLUSION

CCNB1 and AURKA are central to CRPC resistance to vinblastine and affect PCa progression.

Metronomic Chemotherapy: A Systematic Review of the Literature and Clinical Experience

Metronomic chemotherapy, continuous and dose-dense administration of chemotherapeutic drugs with lowered doses, is being evaluated for substituting, augmenting, or appending conventional maximum tolerated dose regimens, with preclinical and clinical studies for the past few decades. To date, the principle mechanisms of its action include impeding tumoral angiogenesis and modulation of hosts' immune system, affecting directly tumor cells, their progenitors, and neighboring stromal cells. Its better toxicity profile, lower cost, and easier use are main advantages over conventional therapies. The evidence of metronomic chemotherapy for personalized medicine is growing, starting with unfit elderly patients and also for palliative treatment. The literature reviewed in this article mainly demonstrates that metronomic chemotherapy is advantageous for selected patients and for certain types of malignancies, which make it a promising therapeutic approach for filling in the gaps. More clinical studies are needed to establish a solidified role for metronomic chemotherapy with other treatment models in modern cancer management.

Assessing outcomes in prostate cancer clinical trials: a twenty-first century tower of Babel

BACKGROUND

Because of the osseous distribution of prostate cancer metastases, progression is more readily identified than response in prostate cancer clinical trials. As a result, there is an increased focus on progression-free survival (PFS) as a phase 2 endpoint. PFS, however, is vulnerable to inter-study design variability. The authors sought to identify and quantify this variability and the resultant error in PFS across prostate cancer clinical trials.

METHODS

The authors reviewed phase 2 clinical trials of cytotoxic agents in castration-resistant metastatic prostate cancer over 5 years to evaluate the policies determining extent of disease and the definitions of disease progression. A simulation model was created to define the degree of error in estimating PFS in 3 hypothetical cohorts (median PFS of 12, 24, and 36 weeks) when the frequency of outcome assessments varies.

RESULTS

Imaging policies for trial entry were heterogeneous, as were the type, timing, and indications for outcome assessments. In the simulation, error in the reported PFS varied according to the interval between assessments. The difference between the detected and the true PFS could vary as much as 6.4 weeks per cycle, strictly resulting from the variability of assessment schedules tested.

CONCLUSIONS

Outcome assessment policies are highly variable in phase 2 studies of castration-resistant prostate cancer patients, despite published guidelines designed to standardize authentication of disease progression. The estimated error in PFS can exceed 6 weeks per cycle, exclusively because of variations in the assessment schedules. Comparisons of PFS times from different studies must be made with circumspection.

Hoosier Oncology Group randomized phase II study of docetaxel, vinorelbine, and estramustine in combination in hormone-refractory prostate cancer with pharmacogenetic survival analysis

PURPOSE

To determine the safety and efficacy of two docetaxel doublets in hormone-refractory prostate cancer (HRPC) patients and to examine the prognostic role of polymorphisms in host genes important to docetaxel metabolism and transport.

EXPERIMENTAL DESIGN

Sixty-four chemotherapy-naive patients with HRPC were randomized to docetaxel and vinorelbine (D, 20 mg/m2 i.v. days 1 and 8; V, 25 mg/m2 i.v. days 1 and 8) or docetaxel and estramustine phosphate (D, 60-70 mg/m2 i.v. day 1; E, 280 mg oral thrice daily days 1-5) administered q21d. Primary end point was clinically significant toxicity. A pharmacogenetic analysis of host genes was done in patients who received at least one cycle of docetaxel therapy.

RESULTS

Grade 3/4 toxicity occurred in 15.6% of DV patients and in 28.6% DE patients. Neither arm exceeded the threshold of clinically significant toxicity. In the DV arm, objective response rate was 33%, prostate-specific antigen response rate was 20%, and median survival was 16.2 months. In the DE arm, objective response rate was 67%, prostate-specific antigen response rate was 43%, and median survival was 19.7 months. Pharmacogenetic analyses showed a significant association between survival beyond 15 months and the ABCG2 421 C > A (Q141K) polymorphism compared with the wild-type (C/C) genotype (66% versus 27%; P = 0.05).

CONCLUSIONS

DV and DE doublets are active with a tolerable toxicity profile in patients with HRPC; however, efficacy does not seem superior to standard single-agent docetaxel. The ABCG2 421 C > A (Q141K) polymorphism may be an important predictor of response and survival in HRPC patients treated with docetaxel-based chemotherapy.