scholarly journals Clinical Development of PARP Inhibitors in Treating Metastatic Castration-Resistant Prostate Cancer

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 860 ◽  
Author(s):  
Jacob J. Adashek ◽  
Rohit K. Jain ◽  
Jingsong Zhang

The approval of upfront abiraterone for castration-sensitive prostate cancer and the approval of enzalutamide and apalutamide for non-metastatic castration-resistant prostate cancer have led to early utilization of potent androgen receptor (AR) signaling inhibitors in treating advanced prostate cancer. There is an unmet need to develop novel therapies beyond targeting AR signaling for metastatic castration-resistant prostate cancer (mCRPC). Poly (ADP-ribose) polymerase inhibitors (PARPi) belong to a class of targeted agents being developed for the treatment of homologous recombination repair (HRR) deficient tumors. Olaparib, rucaparib, niraparib, veliparib, and talazoparib were evaluated in early phase trials as a monotherapy for HRR-deficient mCRPC. Among them, olaparib and rucaparib have breakthrough designations for BRCA1/2-mutated mCRPC. Phase II studies also reported clinical activity of the PARPi and abiraterone combination and the PARPi checkpoint inhibitor combination in HRR-intact mCRPC. Ongoing phase III trials are testing these combinations as frontline or later line treatments for mCRPC. This review summarizes the critical clinical data as well as ongoing clinical trials for developing PARPi in treating mCRPC.

2011 ◽  
Vol 29 (27) ◽  
pp. 3651-3658 ◽  
Author(s):  
Charles J. Ryan ◽  
Donald J. Tindall

Discoveries over the past decade suggest that castration-resistant prostate cancer (CRPC) is sensitive, but not resistant to, further manipulation of the androgen–androgen receptor (AR) axis. Several new therapies that target this axis have demonstrated clinical activity. In this article, preclinical and clinical findings occurring in the field of AR-targeted therapies are reviewed. Reviews of scientific and clinical development are divided into those occurring prereceptor (androgen production and conversion) and at the level of the receptor (AR aberrations and therapies targeting AR directly). Intracrine androgen production and AR amplification, among others, are among the principal aberrancies driving CRPC growth. Phase III data with abiraterone acetate and phase II data with MDV-3100, along with other similar therapies, confirm for the clinician that the scientific findings related to persistent AR signaling in a castrate milieu can be harnessed to produce significant clinical benefit for patients with the disease. Studies aimed at optimizing the timing of their use and exploring the mechanisms of resistance to these therapies are under way. The clinical success of therapies that directly target androgen synthesis as well as the most common aberrancies of the AR confirm that prostate cancer retains dependence on AR signaling, even in the castrate state.


Author(s):  
Oliver Sartor

Overview: Much progress has been made in metastatic castration-resistant prostate cancer (CRPC), and multiple new U.S. Food and Drug Administration (FDA)-approved survival-prolonging drugs are now available. In 2004, docetaxel/prednisone was the first therapy shown to prolong survival. In 2010 and 2011, sipuleucel-T, cabazitaxel/prednisone, and abiraterone/prednisone were FDA approved. Two new agents, radium-223 and MDV-3100, have recently reported large phase III trials prolonging overall survival and will be submitted for regulatory approval in 2012. One can now begin to ask, is there an optimal sequence for therapies in metastatic CRPC? Despite the recent progress, there is much we do not know and virtually no information on this important question. We know that abiraterone/prednisone and cabazitaxel/prednisone are appropriate choices for a patient after receiving docetaxel, but we do not know what, if anything, represents the optimal sequence for abiraterone and cabazitaxel. In fact we do not understand how one therapy may affect the response to a subsequent therapy. We are also aware that the pre- and postdocetaxel spaces represent regulatory rather than biologic divisions. In addition, despite the proven role of docetaxel/prednisone, many patients with CRPC are not considered to be suitable for chemotherapy, and worldwide many never receive any form of chemotherapy. What is the optimal management for these patients? Taken together it is reasonable to assess patient preferences, prior therapies and response/tolerance to prior therapies, burden of disease, comorbidities, current symptoms, drug toxicities, out-of-pocket costs, etc., in clinical decision making. Given the many factors we do not know, it is hard to be dogmatic in approaching the therapeutic options for the patient with CRPC. We will likely soon move beyond the current sequencing paradigm and begin to assess new combinations in a systematic and rational fashion. Perhaps one day, in the not too distant future, we will develop molecular “stratification systems” to better guide therapeutic choices in CRPC.


2010 ◽  
Vol 28 (12) ◽  
pp. 2070-2076 ◽  
Author(s):  
Yang-Min Ning ◽  
James L. Gulley ◽  
Philip M. Arlen ◽  
Sukyung Woo ◽  
Seth M. Steinberg ◽  
...  

Purpose We previously demonstrated that thalidomide appears to add to the activity of docetaxel in metastatic castration-resistant prostate cancer (CRPC). Phase II studies combining docetaxel with bevacizumab have had substantial antitumor activity. We hypothesized that the combination of docetaxel plus these antiangiogenic drugs with different targets would have substantial clinical activity. To explore safety and efficacy, this was tested in mice and in human patients. Patients and Methods Preclinical efficacy of the combination therapy was evaluated in PC3 xenograft mice. Sixty patients with progressive metastatic CRPC received intravenous docetaxel and bevacizumab plus oral thalidomide and prednisone. The primary end point was a prostate-specific antigen (PSA) decline of ≥ 50%. Secondary end points included time to progression, overall survival, and safety. Results In the mouse model, combination therapy of docetaxel, bevacizumab, and thalidomide inhibited tumor growth most effectively. In the clinical trial, 90% of patients receiving the combination therapy had PSA declines of ≥ 50%, and 88% achieved a PSA decline of ≥ 30% within the first 3 months of treatment. The median time to progression was 18.3 months, and the median overall survival was 28.2 months in this group with a Halabi-predicted survival of 14 months. While toxicities were manageable, all patients developed grade 3/4 neutropenia. Conclusion The addition of bevacizumab and thalidomide to docetaxel is a highly active combination with manageable toxicities. The estimated median survival is encouraging, given the generally poor prognosis of this patient population. These results suggest that definitive clinical trials combining antiangiogenic agent combinations with docetaxel are warranted to improve treatment outcomes for patients with metastatic CRPC.


Author(s):  
Karim Fizazi

There is no doubt that more therapeutic progress has been achieved during the last 3 years for patients with metastatic castration-resistant prostate cancer (mCRPC) than during the previous 30 years. During this limited time frame, not only have six compounds (sipuleucel-T, cabazitaxel, denosumab, abiraterone, radium-223, and enzalutamide, listed in chronologic order) yielded positive results in phase III trials, we have also learned that their mechanisms of action are different, making it quite likely that part of their anticancer activity may be incremental. Most of these agents have already been approved. Further progress may well soon complete this recently enlarged armamentarium, with important trials testing new agents derived from existing families of compounds (new endocrine therapies, new immunotherapies, etc.) and exploring the activity of new families of agents (tyrosine kinase inhibitors such as cabozantinib, inhibitors of chaperone proteins like OGX-O11 and OGX-427). The availability of these agents creates a new major challenge for those who conduct clinical research in mCRPC. Will we be able to personalize therapy based on the biology of the individual's tumor, as we are already doing in other neoplasms?


Author(s):  
Benedito A. Carneiro ◽  
Tamara L. Lotan ◽  
Andre de Souza ◽  
Rahul Aggarwal

Genomic characterization of metastatic castration-resistant prostate cancer (mCRPC) has been remodeling the treatment landscape of this disease in the past decade. The emergence of molecularly defined subsets of mCRPC is altering the treatment paradigm from therapeutics with nonspecific activity across the spectrum, including androgen receptor (AR)-directed treatments, docetaxel, and cabazitaxel, to targeted approaches directed at molecular subsets of disease. The meaningful benefit of PARP inhibitors in mCRPC carrying mutations in DNA repair genes demonstrated in a phase III trial epitomizes this transition in the treatment paradigm of mCRPC and brings new challenges related to how to sequence and integrate the targeted therapies on top of the treatments with broad activity in all mCRPC. To enable and sustain the advance of precision oncology in the management of mCRPC, genomic characterization is required, including somatic and germline testing, for all patients with the ultimate goal of longitudinal molecular profiling guiding treatment decisions and sequential treatments of this lethal disease. This article reviews the emerging molecular subtypes of mCRPC that are driving the evolution of mCRPC treatment.


Sign in / Sign up

Export Citation Format

Share Document