Concurrent and adjuvant docetaxel with three-dimensional conformal radiation therapy plus androgen deprivation for high-risk prostate cancer: preliminary results of a multicentre phase II trial

Secondary analysis of late major gastrointestinal and genitourinary toxicities in unfavorable-risk prostate cancer patients receiving docetaxel: Insights from a randomized trial

BACKGROUND

This study sought to evaluate the late toxicity associated with neoadjuvant and concurrent docetaxel and radiation therapy in patients with prostate cancer.

METHODS

A secondary analysis was performed of the phase 3 multicenter randomized trial (Dana-Farber Cancer Institute 05-043) including 350 patients with nonmetastatic unfavorable-risk prostate cancer. Patients were randomized 1:1 to receive androgen deprivation therapy, radiation therapy, and docetaxel versus androgen deprivation therapy and radiation therapy. The study assessed the cumulative incidence rates of grade 2 and grade 3 or higher gastrointestinal, genitourinary, and sexual toxicity. A multivariable Fine and Gray's competing risks regression model adjusted for age at randomization and pelvic lymph node radiation therapy was used to evaluate the treatment effect of docetaxel on time to late genitourinary and gastrointestinal toxicities.

RESULTS

The study included 338 patients who primarily had minimal or no comorbidity (74.9%) and median age 66 years (interquartile range: 61,71). At a median follow-up of 10.2 years, docetaxel was not associated with increased risk of any grade 3 or higher (adjusted hazard ratio [AHR], 0.98; 95% confidence interval [CI], 0.36-2.67; p = .96) or grade 2 gastrointestinal (p = .75), genitourinary (p = .44), and sexual (p = .29) toxicity. Age was associated with increased grade 3 or higher (AHR, 1.08; 95% CI, 1.01-1.16; p = .03) and grade 2 gastrointestinal toxicity (AHR, 1.11; 95% CI, 1.03-1.20; p = .005). A nonsignificant trend (p = .09) toward increased late grade 3 or higher toxicity was observed for pelvic radiation therapy use.

CONCLUSIONS

Docetaxel combined with radiotherapy has an acceptable long-term toxicity profile.

Radiation and Androgen Deprivation Therapy With or Without Docetaxel in the Management of Nonmetastatic Unfavorable-Risk Prostate Cancer: A Prospective Randomized Trial

Although docetaxel is not recommended when managing men with unfavorable-risk prostate cancer (PC) given negative or inconclusive results from previous randomized trials, unstudied benefits may exist.

Harnessing the potential of multimodal radiotherapy in prostate cancer

Radiotherapy in combination with androgen deprivation therapy (ADT) is a standard treatment option for men with localized and locally advanced prostate cancer. However, emerging clinical evidence suggests that radiotherapy can be incorporated into multimodality therapy regimens beyond ADT, in combinations that include chemotherapy, radiosensitizing agents, immunotherapy and surgery for the treatment of men with localized and locally advanced prostate cancer, and those with oligometastatic disease, in whom the low metastatic burden in particular might be treatable with these combinations. This multimodal approach is increasingly recognized as offering considerable clinical benefit, such as increased antitumour effects and improved survival. Thus, radiotherapy is becoming a key component of multimodal therapy for many stages of prostate cancer, particularly oligometastatic disease.

Phase I Trial of Weekly Cabazitaxel with Concurrent Intensity Modulated Radiation and Androgen Deprivation Therapy for the Treatment of High-Risk Prostate Cancer

PURPOSE

Cabazitaxel has been demonstrated to improve the overall survival for men with metastatic castrate-resistant prostate cancer. The purpose of this study was to determine the maximum tolerated dose for concurrent cabazitaxel with androgen deprivation and intensity modulated radiation therapy in men with high-risk prostate cancer.

METHODS AND MATERIALS

Twenty men were enrolled in this institutuional review board-approved phase I clinical trial using a 3 + 3 design. Patients were followed prospectively for safety, efficacy, and health-related quality of life (Expanded Prostate Index Composite). Efficacy was assessed biochemically using the Phoenix definition.

RESULTS

With a median follow-up time of 56 months, the maximum tolerated dose of concurrent cabazitaxel was 6 mg/m². The 5-year biochemical disease-free survival was 73%, despite 75% of patients having very high risk prostate cancer per the National Comprehensive Cancer Network guidelines. Four patients were unable to complete chemotherapy owing to dose-limiting toxicities (eg, rectal bleeding, diarrhea, and elevated transaminase). There was no significant minimally important difference in Expanded Prostate Index Composite patient-reported outcomes for either the urinary or bowel domains; however, there was a significant decrease in the sexual domain.

CONCLUSIONS

This is the first clinical trial of prostate cancer to report on the combination of cabazitaxel and radiation therapy. The maximum tolerated dose of concurrent cabazitaxel with radiation and androgen deprivation therapy was determined to be 6 mg/m². Despite the aggressive nature of the disease, robust biochemical control was observed.

Titanate Nanotubes Engineered with Gold Nanoparticles and Docetaxel to Enhance Radiotherapy on Xenografted Prostate Tumors

Nanohybrids based on titanate nanotubes (TiONts) were developed to fight prostate cancer by intratumoral (IT) injection, and particular attention was paid to their step-by-step synthesis. TiONts were synthesized by a hydrothermal process. To develop the custom-engineered nanohybrids, the surface of TiONts was coated beforehand with a siloxane (APTES), and coupled with both dithiolated diethylenetriaminepentaacetic acid-modified gold nanoparticles (Au@DTDTPA NPs) and a heterobifunctional polymer (PEG₃₀₀₀) to significantly improve suspension stability and biocompatibility of TiONts for targeted biomedical applications. The pre-functionalized surface of this scaffold had reactive sites to graft therapeutic agents, such as docetaxel (DTX). This novel combination, aimed at retaining the AuNPs inside the tumor via TiONts, was able to enhance the radiation effect. Nanohybrids have been extensively characterized and were detectable by SPECT/CT imaging through grafted Au@DTDTPA NPs, radiolabeled with ¹¹¹In. In vitro results showed that TiONts-AuNPs-PEG₃₀₀₀-DTX had a substantial cytotoxic activity on human PC-3 prostate adenocarcinoma cells, unlike initial nanohybrids without DTX (Au@DTDTPA NPs and TiONts-AuNPs-PEG₃₀₀₀). Biodistribution studies demonstrated that these novel nanocarriers, consisting of AuNP- and DTX-grafted TiONts, were retained within the tumor for at least 20 days on mice PC-3 xenografted tumors after IT injection, delaying tumor growth upon irradiation.

Systematic Review of Systemic Therapies and Therapeutic Combinations with Local Treatments for High-risk Localized Prostate Cancer

CONTEXT

Systemic therapies, combined with local treatment for high-risk prostate cancer, are recommended by the international guidelines for specific subgroups of patients; however, for many of the clinical scenarios, it remains a research field.

OBJECTIVE

To perform a systematic review, and describe current evidence and perspectives about the multimodal treatment of high-risk prostate cancer.

EVIDENCE ACQUISITION

We performed a systematic review of PubMED, Embase, Cochrane Library, European Society of Medical Oncology/American Society of Clinical Oncology Annual proceedings, and clinicalTrial.gov between January 2010 and February 2018 following the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement.

EVIDENCE SYNTHESIS

Seventy-seven prospective trials were identified. According to multiple randomized trials, combining androgen deprivation therapy (ADT) with external-beam radiotherapy (EBRT) outperforms EBRT alone for both relapse-free and overall survival. Neoadjuvant ADT did not show significant improvement compared with prostatectomy alone. The role of adjuvant ADT after prostatectomy in patients with high-risk disease is still debated, with lack of data from phase 3 trials in pN0 patients. Novel androgen pathway inhibitors have been tested only in early-phase trials in addition to primary treatment. GETUG 12, RTOG 0521, and nonmetastatic subgroup of the STAMPEDE trial showed improved relapse-free survival for docetaxel in patients treated with EBRT plus ADT, although mature metastasis-free survival data are still pending. Both the SPCG-12 and the VACSP#553 trial showed no improvement in relapse-free survival for adjuvant docetaxel after prostatectomy.

CONCLUSIONS

In contrast to the clearly demonstrated survival benefits of long-term adjuvant ADT when used with EBRT, its role after prostatectomy remains unclear especially in pN0 patients. Adding docetaxel to EBRT-ADT improves relapse-free survival, with immature results on overall survival. Novel androgen receptor pathway inhibitors are currently being tested in the neoadjuvant and adjuvant setting.

PATIENT SUMMARY

Treatment of high-risk prostate cancer is based on a multimodality approach that includes systemic treatments. The best treatment or therapy combination remains to be defined.

Radiosensitizing Silica Nanoparticles Encapsulating Docetaxel for Treatment of Prostate Cancer

The applications of nanoparticles in oncology include enhanced drug delivery, efficient tumor targeting, treatment monitoring, and diagnostics. The "theranostic properties" associated with nanoparticles have shown enhanced delivery of chemotherapeutic drugs with superior imaging capabilities and minimal toxicities. In conventional chemotherapy, only a fraction of the administered drug reaches the tumor site or cancer cells. For successful translation of these formulations, it is imperative to evaluate the design and properties of these nanoparticles. Here, we describe the design of ultra-small silica nanoparticles to encapsulate a radiosensitizing drug for combined chemoradiation therapy. The small size of nanoparticles allows for better dispersion and uptake of the drug within the highly vascularized tumor tissue. Silica nanoparticles are synthesized using an oil-in-water microemulsion method. The microemulsion method provides a robust synthetic route in which the inner hydrophobic core is used to encapsulate chemotherapy drug, docetaxel while the outer hydrophilic region provides dispersibility of the synthesized nanoparticles in an aqueous environment. Docetaxel is commonly used for treatment of resistant or metastatic prostate cancer, and is known to have radiosensitizing properties. Here, we describe a systematic approach for synthesizing these theranostic nanoparticles for application in prostate cancer.

Docetaxel-titanate nanotubes enhance radiosensitivity in an androgen-independent prostate cancer model

Around 40% of high-risk prostate cancer patients who undergo radiotherapy (RT) will experience biochemical failure. Chemotherapy, such as docetaxel (DTX), can enhance the efficacy of RT. Multidrug resistance mechanisms often limit drug efficacy by decreasing intracellular concentrations of drugs in tumor cells. It is, therefore, of interest to develop nanocarriers of DTX to maintain the drug inside cancer cells and thus improve treatment efficacy. The purpose of this study was to investigate the use of titanate nanotubes (TiONts) to develop a TiONts-DTX nanocarrier and to evaluate its radiosensitizing in vivo efficacy in a prostate cancer model. In vitro cytotoxic activity of TiONts-DTX was evaluated using an MTS assay. The biodistribution of TiONts-DTX was analyzed in vivo by single-photon emission computed tomography. The benefit of TiONts-DTX associated with RT was evaluated in vivo. Eight groups with seven mice in each were used to evaluate the efficacy of the nanohybrid combined with RT: control with buffer IT injection ± RT, free DXL ± RT, TiONts ± RT and TiONts-DXL ± RT. Mouse behavior, health status and tumor volume were monitored twice a week until the tumor volume reached a maximum of 2,000 mm³. More than 70% of nanohybrids were localized inside the tumor 96 h after administration. Tumor growth was significantly slowed by TiONts-DTX associated with RT, compared with free DTX in the same conditions (P=0.013). These results suggest that TiONts-DTX improved RT efficacy and might enhance local control in high-risk localized prostate cancer.

The very-high-risk prostate cancer: a contemporary update

BACKGROUND

Treatment of high-risk prostate cancer has evolved considerably over the past two decades, yet patients with very-high-risk features may still experience poor outcome despite aggressive therapy. We review the contemporary literature focusing on current definitions, role of modern imaging and treatment alternatives in very-high-risk prostate cancer.

METHODS

We searched the MEDLINE database for all clinical trials or practice guidelines published in English between 2000 and 2016, with the following search terms: 'prostatic neoplasms' (MeSH Terms) AND ('high risk' (keyword) OR 'locally advanced' (keyword) OR 'node positive' (keyword)). Abstracts pertaining to very-high-risk prostate cancer were evaluated and 40 pertinent studies served as the basis for this review.

RESULTS

The term 'very'-high-risk prostate cancer remains ill defined. The European Association of Urology and National Comprehensive Cancer Network guidelines provide the only available definitions, categorizing those with clinical stage T3-4 or minimal nodal involvement as very high risk irrespective of PSA level or biopsy Gleason score. Modern imaging with multiparametric magnetic resonance imaging and positron emission tomography-prostate-specific membrane antigen scans has a role in pre-treatment assessment. Local definitive therapy by external beam radiation combined with androgen deprivation is supported by several randomized clinical trials, whereas the role of surgery in the very-high-risk setting combined with adjuvant radiation/androgen deprivation therapy is emerging. Growing evidence suggest neoadjuvant taxane-based chemotherapy in the context of a multimodal approach may be beneficial.

CONCLUSIONS

Men with very-high-risk tumors may benefit from local definitive treatment in the setting of a multimodal regimen, offering local control and possibly cure in well selected patients. Further studies are necessary to better characterize the 'very'-high-risk category and determine the optimal therapy for the individual patient.

Mechanistic Insights into Molecular Targeting and Combined Modality Therapy for Aggressive, Localized Prostate Cancer

Radiation therapy (RT) is one of the mainstay treatments for prostate cancer (PCa). The potentially curative approaches can provide satisfactory results for many patients with non-metastatic PCa; however, a considerable number of individuals may present disease recurrence and die from the disease. Exploiting the rich molecular biology of PCa will provide insights into how the most resistant tumor cells can be eradicated to improve treatment outcomes. Important for this biology-driven individualized treatment is a robust selection procedure. The development of predictive biomarkers for RT efficacy is therefore of utmost importance for a clinically exploitable strategy to achieve tumor-specific radiosensitization. This review highlights the current status and possible opportunities in the modulation of four key processes to enhance radiation response in PCa by targeting the: (1) androgen signaling pathway; (2) hypoxic tumor cells and regions; (3) DNA damage response (DDR) pathway; and (4) abnormal extra-/intracell signaling pathways. In addition, we discuss how and which patients should be selected for biomarker-based clinical trials exploiting and validating these targeted treatment strategies with precision RT to improve cure rates in non-indolent, localized PCa.

A phase 2 trial of salvage radiation and concurrent weekly docetaxel after a rising prostate-specific antigen level after radical prostatectomy

PURPOSE/OBJECTIVES

We sought to assess the utility of docetaxel administered concurrently with salvage radiation therapy (SRT) following postprostatectomy biochemical failure (BF).

METHODS AND MATERIALS

Men with postprostatectomy BF were accrued on a single-arm phase 2 clinical trial. SRT doses ranged from 64.8 to 70.2 Gy and were delivered in 1.8-Gy fractions to the prostate bed alone as the clinical target volume with a +1-cm uniform planning target volume expansion. The primary endpoint was progression-free survival at 4 years compared with the Stephenson nomogram estimate. Kaplan-Meier methods were used to assess late toxicity, BF, and distant metastases. An unplanned matched-pair analysis was performed with 19 patients treated with SRT alone.

RESULTS

Nineteen men were accrued and treated. Median follow-up was 4.8 years. Median pre-RT prostate-specific antigen level was 0.7 ng/mL (interquartile range, 0.4-1.3 ng/mL). All 8 cycles of docetaxel were completed in 17 (89%) patients. Acute grade 1-4 toxicities were observed in 79%, 50%, 58%, and 11%, respectively. A total of 68% of acute grade 1 toxicities were related to fatigue, urinary, or bowel symptoms. For grade 2 toxicities, 76% were related to neutropenia, fatigue, or urinary symptoms. Acute grade 3 and 4 toxicities were most commonly neutropenia (84% and 100%, respectively). All late toxicities were grade 1 to 2 with 89% related to bowel or urinary function. Predicted 4-year progression-free survival was 39% and observed was 42% (90% confidence interval [CI], 24-60). Matched-pair analysis demonstrated no significant improvement in BF (P = .96, hazard ratio, 0.98; 90% CI, 0.4-2.3) or distant metastases (P = .09; hazard ratio, 0.3; 90% CI, 0.07-1.2), and no difference between late bowel (P = .60) or urinary toxicity (P = .41).

CONCLUSIONS

Docetaxel can safely be administered concurrently with SRT without significantly impacting posttreatment toxicity. Neutropenia was the most significant acute toxicity. Given the small sample size, no clear clinical benefit was observed. Larger studies are needed to determine the efficacy of concurrent docetaxel in this setting.

Concurrent chemoradiation for high-risk prostate cancer

There are estimated to be 220800 cases of prostate cancer diagnosed in 2015, making up 26% of all cancer diagnoses. Fortunately, adenocarcinoma of the prostate is often a highly treatable malignancy. Even though the majority of prostate cancer patients present with localized disease, prostate cancer still accounts for over 27000 deaths a year. There is a subset of patients that are likely to recur after locoregional treatment that is thought of as a “high-risk” population. This more aggressive subset includes patients with clinical stage greater than T2b, Gleason score greater than 7, and prostate specific antigen greater than 20 ng/dL. The rate of biochemical relapse in this high risk group is 32%-70% within five years of definitive focal therapy. Given these discouraging outcomes, attempts have been made to improve cure rates by radiation dose escalation, addition of androgen depravation therapy, and addition of chemotherapy either sequentially or concurrently with radiation. One method that has been shown to improve clinical outcomes is the addition of chemotherapy to radiotherapy for definitive treatment. Concurrent chemoradiation with 5-fluorouracil, estramustine phosphate, vincristine, docetaxel, and paclitaxel has been studied in the phase I and/or II setting. These trials have identified the maximum tolerated dose of chemotherapy and radiation that can be safely delivered concurrently and established the safety and feasibility of this technique. This review will focus on the addition of concurrent chemotherapy to radiotherapy in the definitive management of high-risk prostate cancer.

Nanoparticle-based brachytherapy spacers for delivery of localized combined chemoradiation therapy

PURPOSE

In radiation therapy (RT), brachytherapy-inert source spacers are commonly used in clinical practice to achieve high spatial accuracy. These implanted devices are critical technical components of precise radiation delivery but provide no direct therapeutic benefits.

METHODS AND MATERIALS

Here we have fabricated implantable nanoplatforms or chemoradiation therapy (INCeRT) spacers loaded with silica nanoparticles (SNPs) conjugated containing a drug, to act as a slow-release drug depot for simultaneous localized chemoradiation therapy. The spacers are made of poly(lactic-co-glycolic) acid (PLGA) as matrix and are physically identical in size to the commercially available brachytherapy spacers (5 mm × 0.8 mm). The silica nanoparticles, 250 nm in diameter, were conjugated with near infrared fluorophore Cy7.5 as a model drug, and the INCeRT spacers were characterized in terms of size, morphology, and composition using different instrumentation techniques. The spacers were further doped with an anticancer drug, docetaxel. We evaluated the in vivo stability, biocompatibility, and biodegradation of these spacers in live mouse tissues.

RESULTS

The electron microscopy studies showed that nanoparticles were distributed throughout the spacers. These INCeRT spacers remained stable and can be tracked by the use of optical fluorescence. In vivo optical imaging studies showed a slow diffusion of nanoparticles from the spacer to the adjacent tissue in contrast to the control Cy7.5-PLGA spacer, which showed rapid disintegration in a few days with a burst release of Cy7.5. The docetaxel spacers showed suppression of tumor growth in contrast to control mice over 16 days.

CONCLUSIONS

The imaging with the Cy7.5 spacer and therapeutic efficacy with docetaxel spacers supports the hypothesis that INCeRT spacers can be used for delivering the drugs in a slow, sustained manner in conjunction with brachytherapy, in contrast to the rapid clearance of the drugs when administered systemically. The results demonstrate that these spacers with tailored release profiles have potential in improving the combined therapeutic efficacy of chemoradiation therapy.

Spatial mapping of functional pelvic bone marrow using FLT PET

The purpose of this study was to determine the ability of regions identified with bony landmarks on CT imaging to accurately represent active bone marrow when compared to FLT PET imaging. These surrogate regions could then be used to create a bone marrow sparing radiation therapy plan when FLT PET imaging is not available. Whole body (WB) FLT PET images were obtained of 18 subjects prior to chemoradiation therapy. The FLT image of each subject was registered to a CT image acquired for that subject to obtain anatomic information of the pelvis. Seventeen regions were identified based on features of the pelvic bones, sacrum, and femoral heads. The probability of FLT uptake being located in each of 17 different CT‐based regions of the bony pelvis was calculated using Tukey's multiple comparison test. Statistical analysis of FLT uptake in the pelvis indicated four distinct groups within the 17 regions that had similar levels of activity. Regions located in the central part of the pelvis, including the superior part of the sacrum, the inner halves of the iliac crests, and the L5 vertebral body, had greater FLT uptake than those in the peripheral regions (p‐value < 0.05). We have developed a method to use CT‐defined pelvic bone regions to represent FLT PET‐identified functional bone marrow. Individual regions that have a statistically significant probability of containing functional bone marrow can be used as avoidance regions to reduce radiation dose to functional bone marrow in radiation therapy planning. However, because likely active bone marrow regions and pelvic targets typically overlap, patient‐specific spatial detail may be advantageous in IMRT planning scenarios and may best be provided using FLT PET imaging.

PACS number: 87.57.uk

[Radiation therapy in locally advanced and/or relapsed urological tumors]

Radiation therapy (RT) plays a fundamental role in the treatment of locally advanced and/or relapsed urological tumors, as well as in palliation, or as definitive treatment, and even where integrated into a multi-modal approach. In operated renal tumors, positive margins or extracapsular extension show a positive impact of postoperative RT, with a reduction of relapses between 100% and 30%, while, in the case of palliation, treatments with RT at high doses are preferred. In advanced cancers of the upper urinary tract, RT plays a limited role, even if it seems to increase the level of disease control locally and, with the combination of cisplatin, survival rates too. An important reduction in the recurrence is also observed in locally advanced tumors of the urethra, with a recurrence of 60% after surgery, 36% after RT and 25% after pairing of the two. In locally advanced tumors of the penis, RT shows poorer results than surgery, and the addition of postoperative RT does not seem to add any further outcome, except where, in the presence of a positive inguinal dissection, the postoperative RT reduces lymph node recurrences by 60%-11%. Interesting data for the preservation of the organ are reported with reference to the combination with chemotherapy. In the tumors of the testis, it is still disputable whether the treatment of residual masses after chemotherapy may be appropriate, with a view to a possible salvage radiotherapy. In the treatment of the prostate, the role of RT is consolidated and evolving with the progress of dose escalation, the association with hormonal therapy, new technologies, new possibilities of IMRT and proton therapy and various studies on multi-modal approaches (hormone therapy, surgery, radiotherapy, chemotherapy). Cystectomy is the gold standard for the treatment of locally advanced bladder cancer, even though there is a revived interest in multimodal treatments (transurethral resection, chemotherapy, RT) that may allow the organ preservation. Postoperative radiotherapy, which can reduce by 50% to 20%-5% local recurrences that are highly correlated with distance failure and with survival, should be revised in the light of modern RT techniques that can further increase local control levels and reduce the toxicity significantly.

Multimodal treatment for high-risk prostate cancer with high-dose intensity-modulated radiation therapy preceded or not by radical prostatectomy, concurrent intensified-dose docetaxel and long-term androgen deprivation therapy: results of a prospective phase II trial

BACKGROUND

The optimal management of high-risk prostate cancer remains uncertain. In this study we assessed the safety and efficacy of a novel multimodal treatment paradigm for high-risk prostate cancer.

METHODS

This was a prospective phase II trial including 35 patients with newly diagnosed high-risk localized or locally advanced prostate cancer treated with high-dose intensity-modulated radiation therapy preceded or not by radical prostatectomy, concurrent intensified-dose docetaxel-based chemotherapy and long-term androgen deprivation therapy. Primary endpoint was acute and late toxicity evaluated with the Common Terminology Criteria for Adverse Events version 3.0. Secondary endpoint was biochemical and clinical recurrence-free survival explored with the Kaplan-Meier method.

RESULTS

Acute gastro-intestinal and genito-urinary toxicity was grade 2 in 23% and 20% of patients, and grade 3 in 9% and 3% of patients, respectively. Acute blood/bone marrow toxicity was grade 2 in 20% of patients. No acute grade ≥ 4 toxicity was observed. Late gastro-intestinal and genito-urinary toxicity was grade 2 in 9% of patients each. No late grade ≥ 3 toxicity was observed. Median follow-up was 63 months (interquartile range 31-79). Actuarial 5-year biochemical and clinical recurrence-free survival rate was 55% (95% confidence interval, 35-75%) and 70% (95% confidence interval, 52-88%), respectively.

CONCLUSIONS

In our phase II trial testing a novel multimodal treatment paradigm for high-risk prostate cancer, toxicity was acceptably low and mid-term oncological outcome was good. This treatment paradigm, thus, may warrant further evaluation in phase III randomized trials.

Phase I trial of weekly docetaxel, total androgen blockade, and image-guided intensity-modulated radiotherapy for localized high-risk prostate adenocarcinoma

BACKGROUND

This was a phase I study to find the maximum tolerable dose (MTD) of weekly docetaxel combined with high-dose intensity-modulated radiotherapy (IMRT) and androgen deprivation therapy (ADT).

PATIENTS AND METHODS

Men with localized high-risk prostate cancer (HRPC) were treated with weekly docetaxel at 10 to 30 mg/m(2) concurrent with IMRT of 77.4 Gy to the prostate and 45 Gy to the seminal vesicles. ADT consisted of a gonadotropin-releasing hormone agonist (GnRHa) and bicalutamide beginning 2 months before and during chemoradiation. GnRHa was continued for 24 months.

RESULTS

Nineteen patients were enrolled. No dose-limiting toxicity (DLT) was seen with docetaxel doses up to 25 mg/m(2). At the 30 mg/m(2) level, 2 of 4 patients experienced DLTs of both grade 3 fatigue and dyspepsia. At 41 months' median follow-up, 2 patients had died--1 from metastatic prostate cancer and the other from heart failure. Two other patients experienced biochemical failure. One patient with bladder invasion at diagnosis experienced late grade 2 urinary hesitancy 9 months after completion of radiotherapy, requiring short-term intermittent catheterization. All patients had erectile dysfunction, but no late toxicities worse than grade 2 were identified.

CONCLUSION

Weekly docetaxel may be combined with high-dose IMRT and long-term ADT up to a MTD of 25 mg/m(2). Acute toxicities and long-term side effects of this regimen were acceptable. Future studies evaluating the efficacy of docetaxel, ADT, and IMRT for localized HRPC should use a weekly dose of 25 mg/m(2) when limiting the irradiated volume to the prostate and seminal vesicles.

Improving outcomes in high-risk prostate cancer with radiotherapy

There have been significant improvements in the radiotherapeutic management of patients with high risk prostate cancer. Randomized trials have clearly demonstrated improved outcomes with the combination of radiotherapy in conjunction with androgen deprivation. While these trials have utilized low doses of radiotherapy in the range of 70 Gy, recent studies have suggested that significant benefits of combined androgen deprivation therapy with dose escalated radiotherapy are also observed. The use of high radiation dose levels in the setting of high risk prostate cancer is important, and strategies which combine external beam radiotherapy with a brachytherapy boost may provide an opportunity for even greater intensification of the radiation dose to the prostate target. Systemic therapies, second generation anti-androgen therapy and novel targeted agents integrated with radiotherapy will open up new vistas and challenges for further improved outcomes in patients with high-risk disease.

Phase I study of concurrent weekly docetaxel, high-dose intensity-modulated radiation therapy (IMRT) and androgen-deprivation therapy (ADT) for high-risk prostate cancer

Study Type - Therapy (phase 1) Level of Evidence 2a What's known on the subject? and What does the study add? High-risk and locally advanced prostate cancers are difficult to cure with the standard regimen of radiation therapy (RT) with concurrent androgen-deprivation therapy (ADT). Multiple studies have explored the addition of docetaxel chemotherapy in attempt to improve patient outcomes. Prior Phase I studies have shown that docetaxel 20 mg/m(2) is a safe dose, when given concurrently with 70 Gy of radiation. But current standard RT for prostate cancer uses higher doses, and it is unclear if concurrent chemotherapy is safe with modern RT. This is a Phase I study that explored the addition of concurrent docetaxel chemotherapy to modern RT (intensity-modulated RT to 78 Gy) plus ADT. The study showed that weekly docetaxel at 20 mg/m(2) is safe with modern RT. At a median follow-up of 2.2 years, biochemical progression-free survival was 94%. This triple-therapy regimen is safe and promising for further evaluation in prospective trials.

OBJECTIVE

•  To evaluate in a phase I trial, the feasibility of adding concurrent weekly docetaxel chemotherapy to high-dose intensity modulated radiation therapy (IMRT) and androgen-deprivation therapy (ADT) for treatment of high-risk prostate cancer.

PATIENTS AND METHODS

•  Patients with high-risk prostate cancer were treated with a luteinising hormone-releasing hormone agonist (starting 2-3 months before IMRT and lasting 2 years), IMRT of 78 Gy to the prostate and seminal vesicles, and weekly docetaxel during RT. •  All patients had computed tomography and bone scans to exclude metastatic disease. •  A standard 3 + 3 design was used for docetaxel dose escalation. Successive patients were treated on dose levels of 10, 15, and 20 mg/m(2) of weekly docetaxel.

RESULTS

•  In all, 18 patients participated in the study: 15 (83%) had Gleason 8-10 disease; the other three had either clinical T3 disease and/or a prostate-specific antigen (PSA) level of >20 ng/mL. •  Grade 3 diarrhoea (a defined dose-limiting toxicity, DLT) occurred in one patient in each of the first two dose levels. However, when the cohorts were expanded, no further DLT was seen. •  Weekly docetaxel at 20 mg/m(2) (dose level 3) was successfully given without DLT. •  No patient had grade 4 or 5 toxicity. •  At a median follow-up of 2.2 years, all patients achieved a PSA nadir of <1 ng/mL, including 13 patients who had an undetectable PSA level. The 2-year biochemical progression-free survival was 94%.

CONCLUSION

•  A dose of 20 mg/m(2) of weekly docetaxel given concurrently with high-dose IMRT and ADT appears safe for further study in patients with high-risk prostate cancer.