Pasquale Rescigno

Plasma AR and abiraterone-resistant prostate cancer

Androgen receptor mutations and amplifications in circulating tumor DNA provide clues to prostate cancer drug resistance. Detecting resistance before it starts Androgen receptor targeting is the cornerstone of prostate cancer treatment. Even when the tumors become “castration-resistant” or no longer sensitive to androgen deprivation, androgen signaling can still be effectively targeted by newer drugs such as abiraterone and enzalutamide, which also inhibit the androgen signaling axis. Romanel et al. analyzed tumor DNA samples from the blood of 97 patients with castration-resistant prostate cancer at different times during the course of treatment with abiraterone. Although some new mutations emerged during therapy, the authors found that androgen receptor amplifications were present from the beginning and correlated with abiraterone resistance, suggesting that detection of these amplifications should be useful for identifying abiraterone-resistant cancers before starting treatment. Androgen receptor (AR) gene aberrations are rare in prostate cancer before primary hormone treatment but emerge with castration resistance. To determine AR gene status using a minimally invasive assay that could have broad clinical utility, we developed a targeted next-generation sequencing approach amenable to plasma DNA, covering all AR coding bases and genomic regions that are highly informative in prostate cancer. We sequenced 274 plasma samples from 97 castration-resistant prostate cancer patients treated with abiraterone at two institutions. We controlled for normal DNA in patients’ circulation and detected a sufficiently high tumor DNA fraction to quantify AR copy number state in 217 samples (80 patients). Detection of AR copy number gain and point mutations in plasma were inversely correlated, supported further by the enrichment of nonsynonymous versus synonymous mutations in AR copy number normal as opposed to AR gain samples. Whereas AR copy number was unchanged from before treatment to progression and no mutant AR alleles showed signal for acquired gain, we observed emergence of T878A or L702H AR amino acid changes in 13% of tumors at progression on abiraterone. Patients with AR gain or T878A or L702H before abiraterone (45%) were 4.9 and 7.8 times less likely to have a ≥50 or ≥90% decline in prostate-specific antigen (PSA), respectively, and had a significantly worse overall [hazard ratio (HR), 7.33; 95% confidence interval (CI), 3.51 to 15.34; P = 1.3 × 10−9) and progression-free (HR, 3.73; 95% CI, 2.17 to 6.41; P = 5.6 × 10−7) survival. Evaluation of plasma AR by next-generation sequencing could identify cancers with primary resistance to abiraterone.

Phase II Study of Sorafenib in Patients With Sunitinib-Refractory Metastatic Renal Cell Cancer

PURPOSE No previous prospective trials have been reported with sorafenib in patients with sunitinib-refractory metastatic renal cell cancer (MRCC). We conducted a multicenter study to determine the activity and tolerability of sorafenib as second-line therapy after sunitinib progression in MRCC. PATIENTS AND METHODS Between January 2006 and September 2008, 52 patients were enrolled onto this single-arm phase II study. All patients received sorafenib 400 mg orally twice a day until disease progression or intolerable toxicity. The primary end point was objective response rate (complete or partial response) evaluated every 8 weeks by use of the Response Evaluation Criteria in Solid Tumors; secondary end points were toxicity, time to progression (TTP), and overall survival (OS). RESULTS All patients were included in response and safety analyses. Partial responses were observed in 9.6% of patients (five of 52 patients; 95% CI, 5% to 17%) after two cycles. Grade 1 to 2 fatigue, diarrhea, nausea/vomiting, rash, and neutropenia were the most common side effects, noted in 16 (30.8%), 19 (36.5%), 20 (38.5%), 19 (36.5%), and 20 patients (38.5%), respectively. The most common grade 3 toxicity was diarrhea, noted in six patients (11.5%). Median TTP was 16 weeks (range, 8 to 40 weeks), and median OS was 32 weeks (range, 16 to 64 weeks). CONCLUSION Although well tolerated, sorafenib shows limited efficacy in sunitinib-refractory MRCC. Further randomized trials comparing sorafenib with other drugs that target different biologic pathways are needed to define the best second-line treatment option in these patients.

PTEN Protein Loss and Clinical Outcome from Castration-resistant Prostate Cancer Treated with Abiraterone Acetate

Background Loss of the tumor suppressor phosphatase and tensin homolog (PTEN) occurs frequently in prostate cancers. Preclinical evidence suggests that activation of PI3K/AKT signaling through loss of PTEN can result in resistance to hormonal treatment in prostate cancer. Objective To explore the antitumor activity of abiraterone acetate (abiraterone) in castration-resistant prostate cancer (CRPC) patients with and without loss of PTEN protein expression. Design, setting, and participants We retrospectively identified patients who had received abiraterone and had hormone-sensitive prostate cancer (HSPC) and/or CRPC tissue available for PTEN immunohistochemical analysis. Outcome measurements and statistical analysis The primary end point was overall survival from initiation of abiraterone treatment. Relationship with outcome was analyzed using multivariate Cox regression and log-rank analyses. Results and limitations A total of 144 patients were identified who had received abiraterone post-docetaxel and had available tumor tissue. Overall, loss of PTEN expression was observed in 40% of patients. Matched HSPC and CRPC tumor biopsies were available for 41 patients. PTEN status in CRPC correlated with HSPC in 86% of cases. Loss of PTEN expression was associated with shorter median overall survival (14 vs 21 mo; hazard ratio [HR]: 1.75; 95% confidence interval [CI], 1.19–2.55; p = 0.004) and shorter median duration of abiraterone treatment (24 vs 28 wk; HR: 1.6; 95% CI, 1.12–2.28; p = 0.009). PTEN protein loss, high lactate dehydrogenase, and the presence of visceral metastases were identified as independent prognostic factors in multivariate analysis. Conclusions Our results indicate that loss of PTEN expression was associated with worse survival and shorter time on abiraterone treatment. Further studies in larger and prospective cohorts are warranted. Patient summary PTEN is a protein often lost in prostate cancer cells. In this study we evaluated if prostate cancers that lack this protein respond differently to treatment with abiraterone acetate. We demonstrated that the survival of patients with loss of PTEN is shorter than patients with normal PTEN expression.

Phase II study of docetaxel re-treatment in docetaxel-pretreated castration-resistant prostate cancer

Study Type – Therapy (cohort)
Level of Evidence 2b

Third-Line Sorafenib After Sequential Therapy With Sunitinib and mTOR Inhibitors in Metastatic Renal Cell Carcinoma

BACKGROUND Sunitinib and everolimus have been approved for first- and second-line treatment, respectively, in metastatic renal cell carcinoma (mRCC). The role of sorafenib, which is approved for second-line treatment after cytokines failure, is presently to be defined. OBJECTIVE To determine whether third-line sorafenib after sequential use of sunitinib and mammalian target of rapamycin inhibitors (everolimus or temsirolimus) is feasible and effective. DESIGN, SETTING, AND PARTICIPANTS One hundred fifty medical records of patients with mRCC treated with first-line sunitinib between January 2006 and January 2010 were reviewed at four participating centers. Data regarding patients treated with the sequence sunitinib-everolimus or temsirolimus-sorafenib were extracted. Central analysis of radiographic images was performed using RECIST criteria to determine progression-free survival (PFS) and overall response rate (oRR) to sorafenib treatment. MEASUREMENTS PFS and oRR to sorafenib were the primary end points. Secondary outcomes were safety and overall survival (OS). RESULTS AND LIMITATIONS Thirty-four patients were eligible for the study. A median PFS of 4 mo (range: 3-6 mo) and a median OS of 7 mo since sorafenib treatment (range: 6-10 mo) were reported. Of the patients, 23.5% showed response to sorafenib, with an overall disease control rate (complete responses plus partial responses plus stable disease) of 44%. Selection bias, data incompleteness, and absence of study design are inevitable limitations of the study, although central review can strengthen the quality of presented data. CONCLUSIONS Third-line sorafenib appears to be active and well tolerated in mRCC after first-line sunitinib and second-line everolimus or temsirolimus, with no patients interrupting sorafenib because of toxicity or lack of compliance. Prospective, placebo-controlled trials are completely lacking and are required in this setting.

Analytical Validation and Clinical Qualification of a New Immunohistochemical Assay for Androgen Receptor Splice Variant-7 Protein Expression in Metastatic Castration-resistant Prostate Cancer

Background The androgen receptor splice variant-7 (AR-V7) has been implicated in the development of castration-resistant prostate cancer (CRPC) and resistance to abiraterone and enzalutamide. Objective To develop a validated assay for detection of AR-V7 protein in tumour tissue and determine its expression and clinical significance as patients progress from hormone-sensitive prostate cancer (HSPC) to CRPC. Design, setting, and participants Following monoclonal antibody generation and validation, we retrospectively identified patients who had HSPC and CRPC tissue available for AR-V7 immunohistochemical (IHC) analysis. Outcome measurements and statistical analysis Nuclear AR-V7 expression was determined using IHC H score (HS) data. The change in nuclear AR-V7 expression from HSPC to CRPC and the association between nuclear AR-V7 expression and overall survival (OS) was determined. Results and limitations Nuclear AR-V7 expression was significantly lower in HSPC (median HS 50, interquartile range [IQR] 17.5–90) compared to CRPC (HS 135, IQR 80–157.5; p < 0.0001), and in biopsy tissue taken before (HS 80, IQR 30–136.3) compared to after (HS 140, IQR 105–167.5; p = 0.007) abiraterone or enzalutamide treatment. Lower nuclear AR-V7 expression at CRPC biopsy was associated with longer OS (hazard ratio 1.012, 95% confidence interval 1.004–1.020; p = 0.003). While this monoclonal antibody primarily binds to AR-V7 in PC biopsy tissue, it may also bind to other proteins. Conclusions We provide the first evidence that nuclear AR-V7 expression increases with emerging CRPC and is prognostic for OS, unlike antibody staining for the AR N-terminal domain. These data indicate that AR-V7 is important in CRPC disease biology; agents targeting AR splice variants are needed to test this hypothesis and further improve patient outcome from CRPC. Patient summary In this study we found that levels of the protein AR-V7 were higher in patients with advanced prostate cancer. A higher level of AR-V7 identifies a group of patients who respond less well to certain prostate cancer treatments and live for a shorter period of time.

Cisplatin and 5-fluorouracil in inoperable, stage IV squamous cell carcinoma of the penis

Study Type – Therapy (case series)

Paclitaxel in Pretreated Metastatic Penile Cancer: Final Results of a Phase 2 Study

BACKGROUND Previously published preliminary findings showed promising activity of paclitaxel in chemotherapy-pretreated metastatic penile cancer. OBJECTIVE To evaluate the activity and safety of paclitaxel in pretreated metastatic penile cancer. DESIGN, SETTING, AND PARTICIPANTS Twenty-five patients were enrolled in a single-arm phase 2 multicentre study and treated with 175 mg/m² paclitaxel at 3-wk intervals until disease progression or irreversible toxicity. MEASUREMENTS The objective response rate was the primary end point. Safety, progression-free survival (PFS), and overall survival (OS) were secondary end points. RESULTS AND LIMITATIONS Partial responses were observed in 20% (5 of 25 patients). Grade 1-2 neutropenia, nausea, and oral mucositis were the most common side effects, noted in 13, 9, and 8 patients, respectively. Grade 3-4 neutropenia was reported in seven patients (28%). Median PFS was 11 wk (95% confidence interval [CI], 7-30); median OS was 23 wk (95% CI, 13-48). Median survival in responders was 32 wk (95% CI, 20-48). One limitation of our study was the limited accrual, which did not reach the target of 27 patients, due to the typical slow enrolment of a rare disease. CONCLUSIONS Final results of this study demonstrate that paclitaxel is moderately active and well tolerated. Further trials, which may also explore the combination of paclitaxel with other agents, are required to confirm our findings.

New perspectives in the therapy of castration resistant prostate cancer.

Prostate Cancer is the most commonly diagnosed malignancy and the second leading cause of cancer-related death in men in the Western World. Docetaxel-based chemotherapy has been the mainstay of treatment until a few years ago for metastatic castration resistant prostatic cancer (mCRPC). Recently, a broad range of therapeutic options has become available for mCRPC in a variety of settings, including chemotherapeutic agents (cabazitaxel), androgen synthesis inhibitors (abiraterone acetate), androgen receptor (AR) inhibitors (enzalutamide) and immunotherapy (sipuleucel-T). Multiple novel targeted agents are at an advanced stage of experimentation, including androgen synthesis inhibitors (TAK700), AR inhibitors (ARN509), radiopharmaceuticals (radium-223) and immunotherapeutic agents (poxvirus-based vaccine, ipilimumab). This review describes in detail the latest results obtained with a the most promising agents in prostate cancer, with a focus on CRPC biology and mechanism of resistance to anti-neoplastic treatment.

Potential value of Gleason score in predicting the benefit of cabazitaxel in metastatic castration-resistant prostate cancer.

AIM This study aimed to identify predictive/prognostic factors in castration-resistant prostate cancer patients treated with cabazitaxel. PATIENTS & METHODS Patients were enrolled from March 2011 to December 2011 in an international expanded access program. In January 2012, when cabazitaxel became commercially available, a prospective study was initiated at University Federico II of Naples and at Rionero in Vulture Hospital. RESULTS Forty-seven patients were enrolled in this study. Patients received a median of nine cycles of cabazitaxel. Median progression-free survival was 7.0 months (95% CI: 5.7-8.0). Seventeen patients were still alive at the time of the analysis, with a median overall survival of 14 months (95% CI: 11-16). At multivariate analysis, a higher Gleason score (≥ 8) appeared to be associated with prolonged progression-free survival (hazard ratio: 0.36; 95% CI: 0.18-0.72); however, the higher Gleason score showed no statistical impact on overall survival. CONCLUSION We hypothesize that the Gleason score has the potential to be incorporated in the clinical decision-making process for definition of treatment strategy in docetaxel-pretreated castration-resistant prostate cancer patients. We encourage further experimentation in this setting.