Understanding the role of new systemic agents in the treatment of prostate cancer

Real-World Treatment Patterns and Overall Survival of Patients with Metastatic Castration-Resistant Prostate Cancer in the US Prior to PARP Inhibitors

Introduction

Therapeutic options for metastatic castration-resistant prostate cancer (mCRPC) patients are continuously advancing. We described mCRPC treatment patterns in the US from 2013 to 2019.

Methods

Patients with a confirmed mCRPC diagnosis and adenocarcinoma histology were included in the US Flatiron Health Electronic Health Record-derived de-identified database. Treatment patterns [including treatment per lines of therapies (LOTs), LOT sequences, and time on treatment] and overall survival (OS) have been described in mCRPC settings.

Results

Of 5213 patients (mean age: 72.6 years), 4374 (83.9%) were treated with ≥ 1 LOT post-mCRPC diagnosis (among those with ≥ 1 LOT, 55.3%, 29.5%, 14.7%, and 6.7% had ≥ 2, 3, 4, and 5 LOTs, respectively). In first line (1L), the main treatment class was next-generation hormonal agents (NHA; 62.5% of patients with ≥ 1 LOT), while the shortest and longest time on 1L were observed for chemotherapy (median 2.8 months) and NHA (median 5.1 months), respectively. The most common LOT sequences were NHA → NHA (29.4% of patients with ≥ 2 LOTs) and NHA → NHA → chemotherapy (16.7% of patients with ≥ 3 LOTs). In Kaplan–Meier analyses, the median OS was 19.4, 14.6, and 11.1 months post-1L, 2L, and 3L start, respectively. Patients who moved rapidly through LOTs had an increased risk of death.

Conclusions

NHA were widely used as 1L therapy in mCRPC patients from 2013 to 2019, but time on 1L NHA treatment was on average < 6 months. While NHA → NHA was the most observed 1L → 2L LOT sequence, a plethora of other LOT sequences were observed. OS was poor, highlighting an unmet need for life-prolonging treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01823-6.

Clinical Outcomes of 177Lu-PSMA Radioligand Therapy in Earlier and Later Phases of Metastatic Castration-Resistant Prostate Cancer Grouped by Previous Taxane Chemotherapy

¹⁷⁷Lu-labeled prostate-specific membrane antigen (PSMA) radioligand therapy using PSMA-617 and PSMA-I&T ligands (¹⁷⁷Lu-PRLT) is an emerging treatment in metastatic castration-resistant prostate cancer (mCRPC). This retrospective study evaluates clinical outcomes of ¹⁷⁷Lu-PRLT in earlier and later phases of mCRPC grouped by previous taxane chemotherapy. Methods: A retrospective analysis was performed on 167 patients with mCRPC who underwent ¹⁷⁷Lu-PRLT between March 2013 and December 2016. Patients were classified as either taxane chemotherapy pretreated (T-pretreated) or naïve (T-naïve) depending on whether they had received taxane-based chemotherapy prior to ¹⁷⁷Lu-PRLT. Clinical outcome for T-pretreated and T-naïve patients was assessed by overall survival (OS), radiographic progression-free survival, and prostate-specific antigen (PSA) response rate. Univariate and multivariable analyses were performed for both T-pretreated and T-naïve patients to determine predictors of outcome. Toxicity was categorized by the Common Terminology Criteria for Adverse Events (version 4.03). Results: Of the 167 patients treated with ¹⁷⁷Lu-PRLT, 83 were T-pretreated and 84 were T-naïve. At baseline, T-pretreated patients had overall poorer performance status, a higher prevalence of bone metastases, higher PSA levels, lower hemoglobin levels, higher alkaline phosphatase (ALP) levels and had received more additional therapies compared with T-naïve patients. Median OS was 10.7 mo for T-pretreated patients and 27.1 mo for T-naïve patients. Median radiographic progression-free survival was 6.0 mo for T-pretreated patients and 8.8 mo for T-naïve patients. PSA response assessment was evaluable in 132 patients and seen in 25 of 62 (40%) T-pretreated patients and 40 of 70 (57%) T-naïve patients. Significant determinates of inferior OS in multivariable analysis for T-pretreated patients were poorer performance status, lower cumulative administered activity, and lower baseline hemoglobin. Higher baseline alkaline phosphatase was the only significant determinate of inferior OS in multivariable analysis for T-naïve patients. Overall ¹⁷⁷Lu-PRLT was safe, with minimal adverse effects evident during follow-up in both T-pretreated and T-naïve patients. Conclusion: ¹⁷⁷Lu-PRLT is a promising therapy in mCRPC, with encouraging outcomes and minimal associated toxicity seen in both our T-naïve and heavily pretreated patient cohorts.

Prostate cancer in Asia: design of a patient registry to inform real-world treatments, outcomes, and quality of life

Background

The incidence of prostate cancer (PC) in Asian countries is increasing for reasons that are not clear. Data describing how PC is diagnosed and treated are fragmented across Asia, with marked intercountry and intracountry differences in outcome and knowledge gaps in clinical diagnostic and treatment practices. To address these knowledge gaps, we have established a PC disease registry with the aim of providing a comprehensive picture of PC diagnosis, prognosis, treatment and outcome, population characteristics, and comorbidities in real-world clinical practice in Asia.

Methods

This is a multinational, multicenter, longitudinal, and observational registry of PC patients presenting to participating tertiary-care hospitals in eight Asian countries (www.clinicaltrials.gov NCT02546908. Registry Identifier: NOPRODPCR4001). Approximately 3500-4000 eligible patients with existing or newly diagnosed high-risk localized PC (cohort 1), nonmetastatic biochemically recurrent PC (cohort 2), or metastatic PC (cohort 3) will be consecutively enrolled and followed-up for 5 years. An enrollment cap of 600 patients each will be applied to cohorts 1 and 2. Disease status is collected at enrollment, and outcome variables captured at 3-monthly intervals include diagnostic/staging, treatments including reason for change, laboratory results, comorbidities, and concomitant medications. Treatments and survival outcomes will be captured real time until study end. Patient-reported quality-of-life will be measured every 6 months, and medical resource utilization summarized at study end. Data analysis will include exploratory analyses of potential associations between multiple risk factors and socioeconomic variables with disease progression and evaluation of various treatments for PC including novel therapies on clinical outcome and health-related quality-of-life outcomes.

Results

3636 men with PC were enrolled until July 2018; 416 in cohort 1, 399 in cohort 2 and 2821 in cohort 3.

Discussion

A total of 3636 patients were enrolled until July 2018. The prospective disease registry will provide comprehensive and wide-ranging real-world information on how PC is diagnosed and treated in Asia. Such information can be used to inform policy development for best practice and direct clinical study design evaluating new treatments.

Quality of Health Information on the Internet for Prostate Cancer

Introduction

To compare (1) the quality of prostate cancer health information on the Internet, (2) the difference in quality between websites appearing earlier or later in the search, and (3) the sources of sponsorship for each of these websites.

Materials and methods

The top 150 listed websites on the Google search engine for each of the 11 search terms related to prostate cancer were analysed. Quality was assessed on whether the website conforms to the principles of the Health On the Net Foundation. Each of these websites was then reviewed to determine the main source of sponsorship. Statistical analysis was performed to determine if the proportion of HON accreditation varied among the different cohorts of listed websites and among the 11 search terms used.

Results

In total, 1650 websites were analysed. Among these, 10.5% websites were HON-accredited. The proportion of HON-accredited websites for individual search terms ranged from 3.3% to 19.3%. In comparison with the search term of "Prostate cancer," four search terms had statistically significant odds ratio of the rate of HON accreditation. Websites 51-150 were statistically less likely to have HON accreditation than websites 1-50. The top three website sponsors were journal/universities (28.8%), commercial (28.1%), and physician/surgeon (26.9%).

Conclusions

The lack of validated and unbiased websites for prostate cancer is concerning especially with increasing use of the Internet for health information. Websites sponsored or managed by the government and national departments were most likely to provide impartial health information for prostate cancer. We need to help our patients identify valid and unbiased online health resources.

A novel prostate cancer immunotherapy using prostate-specific antigen peptides and Candida skin test reagent as an adjuvant

OBJECTIVES

Our group developed the use of the Candida skin test reagent as an adjuvant of cell-mediated immunity in designing a human papillomavirus therapeutic vaccine. Here, this technology is being applied for designing a prostate cancer immunotherapy.

METHODS

Peptides based on the prostate-specific antigen amino acid sequences were selected, synthesized, and evaluated in terms of their (1) solubility, (2) maturation effects on Langerhans cells by fluorescence-activated cell sorter analysis, and (3) recognition by peripheral immune cells from prostate cancer patients using interferon-γ enzyme-linked immunospot assay.

RESULTS

The peptides were soluble in 10 mM succinate at pH of 5 with 5% glycine, and they demonstrated no maturation effects on Langerhans cells from healthy donors. On the other hand, peripheral immune cells from 4 of 10 prostate cancer patients examined had positive responses in enzyme-linked immunospot assay to one or more prostate-specific antigen peptides.

CONCLUSION

In summary, a design and a formulation of a novel prostate cancer immunotherapy are described. The immunogenicity of prostate-specific antigen peptides in some prostate cancer patients supports further development of this immunotherapy.

Impact of curative radiotherapy on the immune status of patients with localized prostate cancer

Combination of radiotherapy with immunotherapy has become an attractive concept for the treatment of cancer. The objective of this study was to assess the effect of curative, normofractionated radiotherapy on peripheral immune lymphocytes in prostate cancer patients, in order to propose a rationale for scheduling of normofractionated radiotherapy with T-cell based immunotherapy. In a prospective study (clinicaltrials.gov: NCT01376674), eighteen patients with localized prostate cancer were treated with radiotherapy with or without hormonal therapy. Irradiation volumes encompassed prostate and, in select cases, elective pelvic nodal regions. Blood samples were collected from all patients before, during, and after radiotherapy, as well as from 6 healthy individuals as control. Normofractionated radiotherapy of prostate cancer over eight weeks had a significant influence on the systemic immune status of patients compared to healthy controls. Absolute leukocyte and lymphocyte counts decreased during treatment as did peripheral blood immune subsets (T cells, CD8+ and naïve CD4+ T cells, B cells). Regulatory T cells and NK cells increased. Proliferation of all immune cells except regulatory T cells increased during RT. Most of these changes were transient. Importantly, the functionality of T lymphocytes and the frequency of antigen-specific CD8+ T cells were not affected during therapy. Our data indicate that combination of normofractionated radiotherapy with immunotherapy might be feasible for patients with prostate cancer. Conceptually, beginning with immunotherapy early during the course of radiotherapy could be beneficial, as the percentage of T cells is highest, the percentage of regulatory T cells is lowest, and as the effects of radiotherapy did not completely subside 3 months after end of radiotherapy.

Cytoreductive prostate radiotherapy in oligometastatic prostate cancer: a single centre analysis of toxicity and clinical outcome

Objectives

The current standard of care for patients with metastatic prostate cancer (mPCa) at diagnosis is androgen deprivation therapy (ADT) with or without anti-androgen and chemotherapy. The aim of this study was to define the role of a local radiotherapy (RT) treatment in the mPCa setting.

Methods

We retrospectively reviewed data of patients with PCa and bone oligometastases at diagnosis treated in our institution with ADT followed by cytoreductive prostate-RT with or without RT on metastases. Biochemical and clinical failure (BF, CF), overall survival (OS) and RT-toxicity were assessed.

Results

We identified 22 patients treated with ADT and external-beam RT on primary between June 2008 and March 2016. All of them but four were also treated for bone metastases. RT on primary with moderately and extremely hypofractionated regimes started after 10.3 months (3.9–51.7) from ADT. After a median follow-up of 26.4 months (10.3–55.5), 20 patients are alive. Twelve patients showed BF after a median time of 23 months (14.5–104) and CF after a median of 23.6 months (15.3–106.1) from the start of ADT. Three patients became castration resistant, starting a new therapy; median time to castration resistance was 31.03 months (range: 29.9–31.5 months). According to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC), only one patient developed acute grade 3 genitourinary toxicity. No late grade >2 adverse events were observed.

Conclusion

Prostate RT in oligometastatic patients is safe and offers long-lasting local control. When compared to ADT alone, RT on primary seems to improve biochemical control and long-term survival; however, this hypothesis should be investigated in prospective studies. Further research is warranted.

Pretreatment 3T multiparametric MRI staging predicts for biochemical failure in high-risk prostate cancer treated with combination high-dose-rate brachytherapy and external beam radiotherapy

PURPOSE

To determine whether pretreatment 3T multiparametric MRI (mpMRI) staging impacts biochemical recurrence-free survival (BRFS) or distant metastasis-free survival (DMFS) for men with high-risk prostate cancer treated with combination high-dose-rate (HDR) brachytherapy and external beam radiation therapy (EBRT).

MATERIALS AND METHODS

This institutional review board-approved retrospective study included a cohort of 37 men with high-risk prostate cancer treated with HDR brachytherapy and EBRT after 3T mpMRI. Kaplan-Meier analysis was used to evaluate whether mpMRI evidence of extracapsular extension or seminal vesicle invasion (SVI) resulted in differences in BRFS or DMFS. Pretreatment and treatment-related variables were evaluated for association with biochemical failure (Phoenix definition) and distant metastatic failure using univariate Cox regression analysis.

RESULTS

The median prostate-specific antigen at diagnosis was 9 ng/mL (range 2-100). Biopsy Gleason score (bGS) was ≤8 in 38% and nine in 62%. Clinical T-category was T1-T2 in 89%, T3a in 8%, and T3b in 3%. With a median followup of 30.6 months, actuarial 3-year BRFS and DMFS were 76% and 86%, respectively. Kaplan-Meier analysis revealed that mpMRI evidence of extracapsular extension or SVI resulted in significantly higher rates of both biochemical recurrence and distant failure. Using Cox regression analysis, only mpMRI evidence of SVI vs. no SVI predicted for biochemical failure (hazard ratio 13.98, p = 0.0055).

CONCLUSIONS

For high-risk prostate cancer treated with combination HDR brachytherapy and EBRT, mpMRI evidence of SVI predicted for biochemical failure, whereas traditional pretreatment variables did not. Therefore, pretreatment 3T mpMRI appears useful for identifying men who may benefit from treatment intensification.