Optimizing the care of patients with advanced prostate cancer in the UK: current challenges and future opportunities

What's known on the subject? and What does the study add? Treatment options in the UK for men with metastatic castration-resistant prostate cancer (mCRPC) have been limited, and there is no standard approach, particularly in the second-line setting. The absence of a standard approach is further confounded by the differing definitions and terminologies still used in clinical practice to describe this group of patients (e.g. androgen-independent prostate cancer, hormone refractory prostate cancer, CRPC). With multiple new treatment options emerging, it will be critical to identify key considerations in our decision-making process and to establish an optimum, standardized approach to treatment so that new therapies can be assimilated into an mCRPC treatment algorithm and our routine clinical practice. Most UK oncologists consider patients with advanced, symptomatic prostate cancer as eligible for chemotherapy, although a poor performance status, significant co-morbid factors, advancing age, and the presence of asymptomatic disease with slowly rising prostate-specific antigen levels would prevent chemotherapy use. The decision to retreat with chemotherapy is largely driven by prior response to first-line chemotherapy. Many UK oncologists feel that UK clinical practice is likely to change over the next 5 years, with abiraterone acetate, MDV3100 and cabazitaxel likely to have the most positive impacts in the treatment of mCRPC.

OBJECTIVES

To evaluate the current management of patients with advanced prostate cancer by UK oncologists. To gain insights into the future role of emerging therapies.

MATERIALS AND METHODS

A semi-structured questionnaire was issued by the British Uro-oncology Group to society members during a closed meeting in September 2010. Emerging therapies evaluated were: abiraterone acetate, aflibercept, bevacizumab, cabazitaxel, custirsen, MDV3100, sipuleucel-T and zibotentan.

RESULTS

Eighty of 98 (82%) surveys were completed. Responders had on average 189 new referrals, and treated 126 patients with advanced prostate cancer each year. Chemotherapy was used by 86% of responders for patients with symptomatic metastatic castration-resistant prostate cancer (mCRPC), although poor performance status, advancing age and slowly rising prostate-specific antigen levels would prevent chemotherapy use. The decision to retreat with chemotherapy was largely driven by prior response to first-line chemotherapy, with docetaxel preferred for those responding. Many (78%) felt that UK clinical practice was likely to change over the next 5 years, and that abiraterone acetate, MDV3100 and cabazitaxel would have the most positive impact. Opinions regarding the future use of aflibercept and custirsen were mixed. Few (≤3%) would use zibotentan or bevacizumab in the future based on recent negative phase III study results, or because of cost and complexity for sipuleucel-T.

CONCLUSIONS

Although emerging therapies for mCRPC mean that the future is bright, guidelines are needed to ensure optimum use and sequencing of treatments. Additional costs and anticipated workload associated with new agents will require careful consideration.

Phase II trial of docetaxel, cisplatin, 5-fluorouracil (TPF) in locally advanced and metastatic squamous cell carcinoma (SCC) of the penis (CRUK/09/001)

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Background: Chemotherapy for penis cancer is used to palliate metastatic disease and treat locally-advanced disease. Pathologic similarities to head and neck SCC suggest that adding docetaxel (T) to platinum-based regimens may enhance efficacy.

Methods: A single-stage single-arm phase II trial was conducted. Eligible patients had measurable, histologically proven penile SCC staged M1; or T4, any N, M0; or any T, N3/inoperable N2, M0; or any T, N1, M0 with Multi-Disciplinary Team agreement for chemotherapy as first-line therapy. Treatment was three 21-day cycles of TPF (day 1: T 75mg/m2, P 60mg/m2; days 1-5: F 750mg/m2/day). In 26 evaluable patients ≥14 responses were required to conclude a response rate of ≥60% (p0=0.35, p1=0.60, α=0.1, β=0.2; Fleming-A’Hern design). Primary endpoint was overall response rate at completion/discontinuation of trial treatment. Secondary endpoints included safety, tolerability, progression-free survival (PFS) and overall survival (OS).

Results: 29 patients (median age 61 years) were recruited from 9 UK centres between Sept 2009 and Dec 2010. 8 patients were M1. 17 patients had performance status (PS) 0, 11 PS1, 1 PS2. 3 patients discontinued treatment early for reasons other than progression. Dose reductions/delays were reported for 13 patients. 28 patients have on-treatment toxicity data: 19 (68%) experienced grade 3/4 toxicity, with neutropenia most common (n=13, 46%). 7 patients (25%) experienced febrile neutropenia and/or neutropenic sepsis. 10/26 patients (38.5%, 95% CI: 20.2% - 59.4%) in the evaluable population responded. Twelve month PFS was 39.1% (95% CI: 20.9% - 56.8%; median PFS (all 29 patients/M1/M0): 7.1/ 3.1/ 9.6- months). Twelve month OS was 54.6% (34.9% - 70.6%; median OS (all patients/M1/M0): 13.7/ 6.9/ not reached yet-months).

Conclusions: UK clinicians successfully recruited to a multi-centre trial in penis cancer, establishing a network of centres for future studies. Toxic effects of TPF were common but not unexpected. The trial did not reach its target response rate of ≥60% to justify further investigation although PFS and OS in this cohort compares favourably to reported data in literature.

Cabazitaxel for metastatic castration-resistant prostate cancer (mCRPC): Interim safety and quality-of-life (QOL) data from the U.K. early access program (NCT01254279)

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Background: Cabazitaxel, a tubulin-binding taxane, improved survival in mCRPC in the TROPIC trial. Notable toxicities were neutropenia and diarrhoea. We report interim safety and QOL data from a single arm multicentre open label study providing early access to cabazitaxel in the UK.

Methods: Patients recruited from 12 centres received cabazitaxel 25mg/m2 intravenously every 3 weeks and prednisolone 10mg daily. Safety assessments were performed before each cycle. Patients completed the EQ-5D questionnaire and health state visual analogue scale (VAS) at baseline and at alternate cycles. Patients recruited before March 31st 2011 are included in the safety analysis. QOL data collected before July 31st 2011 at baseline (n=62), cycle 2 (n=50) and cycle 4 (n=26) are included.

Results: Median age was 68 years; 24% were aged over 75 years. 93% had bone metastases. 50% had experienced disease progression during or within 3 months of docetaxel and the remaining 50% within 3-6 months. A median of 3 cycles of cabazitaxel were completed with 99% relative dose intensity. 83% continued cabazitaxel at the time of safety analysis. 7 patients stopped before completing the full course, 5 of these were due to disease progression. One treatment related death occurred within 30 days of the last cabazitaxel infusion (2.4%). 85% of patients received granulocyte-colony stimulating factor prophylaxis from cycle 1. The proportion of patients reporting no pain or discomfort increased between baseline, cycle 2 and cycle 4 (22.6% to 38% to 50%). Anxiety and depression, mobility and self-care scores from EQ-5D were stable. Median VAS health state increased from baseline (75%) to cycle 4 (79%).

Conclusions: Improvements in pain control and health states were reported during early stages of cabazitaxel treatment. Other EQ-5D QOL measures were stable. Severe toxicity was rare. Results will be updated from final analysis in late 2011.

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P4-16-09: Health Resource Utilization (HRU) Associated with Skeletal-Related Events (SREs) in Advanced Breast Cancer Patients with Bone Metastases: Results from a Prospective Multinational Observational Study

Background Patients with advanced breast cancer and bone metastases suffer from skeletal complications (SREs, defined as spinal cord compression [SCC], surgery to bone [SB], pathologic fracture [PF] or radiation to bone [RB]). Planning future resource requirements and estimating the value of new treatment options requires prospective data on the health resource burden. However, there is a lack of these data in the literature.

Materials and Methods Patients had bone metastases secondary to advanced breast cancer and were eligible to be included in the study if they had: at least one SRE within 90 days prior to enrolment; life expectancy >6 months; ECOG≤2. HRU (number and length of inpatient hospitalizations, outpatient visits, emergency room visits, number of procedures, etc) associated with SREs was collected retrospectively for 90 days prior to enrolment and prospectively for up to 18–21 months. Attribution of HRU to each SRE was determined independently by the investigators. This pooled European analysis includes data for breast cancer patients from centers in Germany, Italy, Spain and UK.

Results A total of 223 eligible patients with breast cancer and bone metastases were enrolled from the four countries. A total of 118 of 457 SREs (25.8%) were associated with inpatient stays with a mean duration of 18.2 (SD=15.7) days per inpatient stay (for the total 125 stays; a single SRE could contribute multiple hospitalizations). The length of inpatient stays varied by facility (i.e., oncology, radiation, surgical) and SRE type. The most common SRE requiring hospitalization was SB (42 of 54 events [77.8%]) with 45 inpatient stays requiring an average length of stay of 15.1 (SD=16.8) days. The least common SRE requiring hospitalization, RB (27 of 279 events [9.7%]), was still associated with 23 inpatient stays with an average of 16.7 (SD=12.4) days per inpatient stay. A total of 342 SREs (74.8%) required an outpatient visit and 159 (34.8%) required >5 visits. As expected, RB was associated with the highest number of outpatient visits (239 of 279 [85.7%] SREs). SB and PF were associated with fewer outpatient visits with 23 of 54 (42.6%) of 54 SREs and 66 of 105 (62.9%) SREs requiring a visit, respectively. 22 of 457 (4.8%) SREs were associated with an emergency room visit.

Discussion SREs can lead to lengthy hospitalizations and numerous outpatient visits. Neither pain requiring opioid use nor changes in cancer therapy to treat bone pain were reported as SREs, although they may have led to additional inpatient and outpatient visits. Thus, HRU estimated in this study likely underestimates overall HRU associated with SREs in advanced breast cancer patients. Relatively low utilization of emergency room visits reported here may be due to emergency care provided directly by the specialist oncology unit or the patient visiting a different institution. Preventing SREs in advanced breast cancer patients may help to reduce the financial burden to the European healthcare systems.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-16-09.

Common seed analysis to identify off-target effects in siRNA screens

Genome-scale small interfering RNA (siRNA) screens have become an increasingly popular approach to new target identification and pathway elucidation. However, the large data sets generated from siRNA screens have demonstrated high false-positive rates and the requirement for extensive experimental triage to distinguish true hits. A number of groups have independently reported the presence of siRNAs with identical seed sequences among their top screening hits. Based on these observations, we have developed a comprehensive technique for detecting and visualizing seed-based off-target effects in siRNA screening data. This is accomplished by analyzing the behavior of siRNAs that share identical seed sequences, which we refer to as common seed analysis (CSA). By applying these techniques to primary screening data of the Wnt pathway, we identify 158 distinct seed sequences that have a statistically significant effect on the assay. The promiscuous seed sequences identified in this manner can then be discounted in the analysis of follow-up experiments using single siRNAs. The ability to detect off-target effects when sufficient numbers of siRNAs share a common seed has significant implications for the design of siRNA screening experiments, data analysis, hit selection, and library design.

Metastatic Castrate-Resistant Prostate Cancer: New Landscape, New Challenges

Just 5 years after docetaxel was recommended by the National Institute for Health and Clinical Excellence as the standard of care for metastatic castrate-resistant prostate cancer, a novel taxane—cabazitaxel—has been licensed in Europe and the USA for a similar indication. It is authorised for use in patients whose disease progresses after docetaxel, for whom it has been shown to provide a survival benefit over current palliative strategies. However, it is not the only new treatment for this population of patients. The hormonal agent abiraterone has also been licensed in the USA, and is expected to receive a European licence later this year, the sipuleucel-T vaccine has been approved in the USA, and other agents are on the near horizon. While these advances are undoubtedly welcome, much thought will need to be given to their optimal use in terms of patient selection, the timing/sequencing of treatment, and to the design of the prostate cancer treatment paradigm. It will also be important to consider the impact that new agents will have on healthcare spending and capacity.

Static versus dynamic intensity-modulated radiotherapy: Profile of integral dose in carcinoma of the nasopharynx

This study is aimed to evaluate the impact of static and dynamic intensity modulated radiotherapy (IMRT) delivery techniques planned with Eclipse TPS on the integral dose to the healthy normal tissue surrounding the tumor-bearing area and to the volume receiving doses < 5 Gy in patients with carcinoma nasopharynx treated with Simultaneous Integrated Boost IMRT (SIB-IMRT). Ten patients with carcinoma nasopharynx were chosen for this dosimetric study. IMRT plans were generated with 6X using dynamic multileaf collimator (DMLC) and static multileaf collimator (SMLC) with 5, 10 and 15 intensity levels (L). Integral dose, volume receiving 5 Gy, number of monitor units (MU) is compared against DMLC. The mean difference in the MU delivered per fraction between 5, 10 and 15 L SMLC and DMLC was -13.25% (P < 0.001, with paired t test), -11.82% (P < 0.001) and -10.81% (P < 0.001), respectively. The mean difference in the integral dose with 5, 10 and 15 L compared to DMLC was -2.96% (P < 0.001), -2.67% (P = 0.016) and -0.39% (P = 0.430), respectively. However, the difference in low-dose volume (V5Gy) was statistically insignificant with mean difference of 0.60% (P = 0.23), 1.18% (P = 0.017) and 1.70% (P = 0.078), respectively for 5, 10 and 15 L compared to DMLC. Our results show that while choosing the IMRT delivery technique using conventional MLC the concerns about integral dose and volume receiving very low doses such as 5 Gy can be ignored.

Green tea extract (epigallocatechin-3-gallate) reduces efficacy of radiotherapy on prostate cancer cells

OBJECTIVES

To assess the influence of epigallocatechin-3-gallate (EGCG) on the efficacy of ionizing radiation on prostate cancer cells because of the increased use of dietary interventions, especially by patients with prostate cancer. Radiotherapy is used to treat localized prostate cancer. Some people consume green tea (EGCG) as a chemopreventive agent against prostate cancer. Green tea can act as an antioxidant and induce superoxide dismutase enzymes, which could scavenge the free oxygen radicals generated by radiotherapy.

METHODS

Prostate cancer cell line DU145 cells were treated with EGCG or radiotherapy, or both. Cell death was assessed using trypan blue cell counting, and apoptosis was confirmed by assessing poly (adenosine phosphate ribose) polymerase cleavage. The antioxidant potential was assessed using Western immunoblotting for manganese superoxide dismutase and copper zinc superoxide dismutase enzymes. Radiotherapy was delivered using a linear accelerator. Cell cycle analysis was performed using flow cytometry.

RESULTS

Radiotherapy at 3.5 Gy induced a 5.9-fold increase in apoptosis of DU145 cells. Subapoptotic doses of EGCG (1.5-7.5 μM) significantly reduced ionizing radiation-induced apoptosis (P < .001), with the inhibitory effect of EGCG on ionizing radiation being most effective when added 30 minutes before radiotherapy (P < .001). In addition, when radiotherapy and EGCG were used together, an approximate 1.5-fold increase in manganese superoxide dismutase levels was seen compared with the control and a 2-fold increase compared with radiotherapy alone.

CONCLUSIONS

Radiotherapy is effective in inducing apoptosis in DU145 cells, but its effect was significantly reduced in the presence of EGCG, and this was associated with an increase in the induction of manganese superoxide dismutase.

Integral dose to the carotid artery in intensity modulated radiotherapy of carcinoma nasopharynx: extended field IMRT versus split-field IMRT

AIM

To evaluate the integral dose to carotid vessels in extended field intensity modulated radiotherapy (IMRT) (including the lower neck nodes in IMRT field) and split field IMRT (using separate single anterior field to treat lower neck nodes) in cancer nasopharynx.

MATERIALS AND METHODS

Dosimetric data from 10 patients of carcinoma nasopharynx, undergoing IMRT, were evaluated in this prospective study. The carotid vessels were contoured from sternoclavicular joints upto the base of skull. IMRT plans were generated for all patients with extended field and split field IMRT techniques using nine coplanar beams with 6 MV photons. A dose of 70 Gy to planning target volume (PTV) 70 Gy, 59.4 Gy to PTV 59.4 Gy and 54 Gy to PTV 54 Gy was delivered in 33 fractions. The dose constraints were similar for both the techniques. The integral dose to the carotid arteries was calculated as the mean dose times the volume (mean dose Χ volume) in units of liter-gray.

RESULTS

The mean dose to the carotid vessels in the extended field IMRT was 63.88 ± 0.97 Gy (mean dose ± SD) and it was 64.43 ± 0.73 Gy for the split field technique. The integral dose in the extended field versus split field technique was 0.29 ± 0.0207 and 0.32 ± 0.0213 liter-gray, respectively. The difference was statistically significant (P < 0.013).

CONCLUSIONS

Extended field IMRT delivers a slightly lower integral dose to carotid arteries in treatment of cancer nasopharynx while maintaining good dose homogeneity to the PTV 54 Gy and can be preferred over split field radiotherapy.