Patient selection for focal therapy of localized prostate cancer

The potential of CAR T cell therapy for prostate cancer

Chimeric antigen receptor (CAR) T cell immunotherapy involves the genetic modification of the patient's own T cells so that they specifically recognize and destroy tumour cells. Considerable clinical success has been achieved using this technique in patients with lymphoid malignancies, but clinical studies that investigated treating solid tumours using this emerging technology have been disappointing. A number of developments might be able to increase the efficacy of CAR T cell therapy for treatment of prostate cancer, including improved trafficking to the tumour, techniques to overcome the immunosuppressive tumour microenvironment, as well as methods to enhance CAR T cell persistence, specificity and safety. Furthermore, CAR T cell therapy has the potential to be combined with other treatment modalities, such as androgen deprivation therapy, radiotherapy or chemotherapy, and could be applied as focal CAR T cell therapy for prostate cancer.

Targeted Toxins for the Treatment of Prostate Cancer

Prostate cancer is the second most common cancer and the fifth leading cause of cancer deaths worldwide. Despite improvements in diagnosis and treatment, new treatment options are urgently needed for advanced stages of the disease. Targeted toxins are chemical conjugates or fully recombinant proteins consisting of a binding domain directed against a target antigen on the surface of cancer cells and a toxin domain, which is transported into the cell for the induction of apoptosis. In the last decades, targeted toxins against prostate cancer have been developed. Several challenges, however, became apparent that prevented their direct clinical use. They comprise immunogenicity, low target antigen binding, endosomal entrapment, and lysosomal/proteasomal degradation of the targeted toxins. Moreover, their efficacy is impaired by prostate tumors, which are marked by a dense microenvironment, low target antigen expression, and apoptosis resistance. In this review, current findings in the development of targeted toxins against prostate cancer in view of effective targeting, reduction of immunogenicity, improvement of intracellular trafficking, and overcoming apoptosis resistance are discussed. There are promising approaches that should lead to the clinical use of targeted toxins as therapeutic alternatives for advanced prostate cancer in the future.

Assessment of the need for DCE MRI in the detection of dominant lesions in the whole gland: Correlation between histology and MRI of prostate cancer

The purpose of this study was to evaluate the utility of dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) in the detection of dominant prostate tumors with multi-parametric MRI of the whole gland. Combined diffusion tensor imaging (DTI) and DCE MRI from 16 patients with biopsy-proven prostate cancer and no previous treatment were acquired with a 3.0-T MRI scanner prior to radical prostatectomy, and used to identify dominant tumors. MRI results were validated by whole-mount histology. Paired t-test and Wilcoxon test, logistic generalized linear mixed effect models and receiver operating characteristic (ROC) analyses were used for the estimation of the statistical significance of the results. In the peripheral zone (PZ), the areas under the ROC curve (ROC-AUC) were 0.98 (sensitivity, 96%; specificity, 98%) for DTI, 0.96 (sensitivity, 92%; specificity, 97%) for DCE and 0.99 (sensitivity, 98%; specificity, 98%) for DTI + DCE. In the entire prostate, the ROC-AUC values were 0.96 (sensitivity, 84%; specificity, 95%) for DTI, 0.87 (sensitivity, 45%; specificity, 94%) for DCE and 0.96 (sensitivity, 88%; specificity, 98%) for DTI + DCE. The increase in ROC-AUC by the addition of DCE was not statistically significant in either PZ or the entire prostate. The results of this study have shown that DTI identified dominant tumors with high accuracy in both PZ and the entire prostate, whereas the inclusion of DCE MRI had no significant impact on the identification of either PZ or entire prostate dominant lesions. Our results suggest that the inclusion of DCE MRI may not increase the accuracy of dominant lesion detection, allowing for faster, better tolerated imaging studies.

3-T multiparametric MRI characteristics of prostate cancer patients suspicious for biochemical recurrence after primary focal cryosurgery (hemiablation)

INTRODUCTION

We aimed to report on multiparametric MRI (mpMRI) characteristics of post-primary focal cryosurgery (PFC) patients suspected of biochemical recurrence (BCR) by the Phoenix criteria.

METHODS

We retrospectively reviewed all patients at our institution who had undergone PFC. Prostate-specific antigen nadir was determined using 2 or more post-PFC values. Suspicion of BCR was determined using the Phoenix criteria (nadir + 2 ng/ml). At the discretion of the physician, pre-and post-PFC 3-T mpMRIs were obtained and in a few cases biopsies were performed.

RESULTS

Ninety (58.4%) of 154 consecutive patients who underwent PFC were included in our analysis and had a median (range) age and prostate volume of 66.5 (48-82) years and 40.5 (16-175) ml, respectively. Of those suspected of BCR (37/90, 41.1%), with a median time to BCR of 19.9 (7.0-38.5) months, 27 patients (73.0%) underwent a post-PFC mpMRI. Twenty-two (81.5%) of these mpMRIs were found with 24 suspicious lesions. A considerable number (9/24, 37.5%) of these lesions were located in the central gland of the prostate. Seven of 24 lesions exhibited adverse mpMRI characteristic; 4 (16.7%) had capsular contact, 2 (8.2%) showed frank extracapsular extension, and 1 (4.2%) showed seminal vesicle invasion. Five (45.5%) of 11 patients with positive post-PFC mpMRIs were positive on biopsy (4/5, 80% were clinically significant prostate cancer).

CONCLUSION

Post-PFC mpMRI, at Phoenix suspicion of BCR, may help identify a significant number of patients failing post-PFC.

Predictors of biochemical recurrence after primary focal cryosurgery (hemiablation) for localized prostate cancer: A multi-institutional analytic comparison of Phoenix and Stuttgart criteria

BACKGROUND

The Phoenix definition (PD) and Stuttgart definition (SD) designed to determine biochemical recurrence (BCR) in patients with postradiotherapy and high-intensity focused ultrasound organ-confined prostate cancer are being applied to follow patients after cryosurgery. We sought to identify predictors of BCR using the PD and SD criteria in patients who underwent primary focal cryosurgery (PFC).

MATERIALS AND METHODS

We performed a retrospective review of patients who underwent PFC (hemiablation) at 2 referral centers from 2000 to 2014. Patients were followed up with serial prostate-specific antigen (PSA). PSA levels, pre- and post-PFC biopsy, Gleason scores, number of positive cores, and BCR (PD = [PSA nadir+2ng/ml]; SD = [PSA nadir+1.2ng/ml]) were recorded. Patients who experienced BCR were biopsied, monitored carefully or treated at the discretion of the treating urologist. Cox regression and survival analyses were performed to assess time to BCR using PD and SD.

RESULTS

A total of 163 patients were included with a median follow-up of 36.6 (interquartile range: 18.9-56.4) months. In all, 64 (39.5%) and 98 (60.5%) experienced BCR based on PD and SD, respectively. On multivariable Cox regression, the number of positive pre-PFC biopsy cores was an independent predictor of both PD (hazard ratio [HR] = 1.4, P = 0.001) and SD (HR = 1.3, P = 0.006) BCRs. Post-PFC PSA nadir was an independent predictor of BCR using the PD (HR = 2.2, P = 0.024) but not SD (HR = 1.4, P = 0.181). Survival analysis demonstrated a 3-year BCR-free survival rate of 56% and 36% for PD and SD, respectively. Of those biopsied after BCR, 14/26 (53.8%) using the PD and 18/35 (51.4%) using the SD were found to have residual/recurrent cancer. Of those with prostate cancer on post-PFC biopsy, 57.1% of those with BCR by the PD and 66.7% of those with BCR by the SD were found to have a Gleason score ≥7.

CONCLUSION

Both the PD and the SD may be used to determine BCR in post-PFC patients. However, the ideal definition of BCR after PFC remains to be elucidated.

Pelvic applications of MR-guided high intensity focused ultrasound

MR-guided high intensity focused ultrasound (MRg HIFU) is a novel method of tissue ablation that incorporates high energy focused ultrasound for tissue heating and necrosis within an MR scanner that provides simultaneous stereotactic tissue targeting and thermometry. To date, MRg HIFU has been used primarily to treat uterine fibroids, but many additional applications in the pelvis are in development. This article reviews the basic technology of MRg HIFU, and the use of MRg HIFU to treat uterine fibroids, adenomyosis, and prostate cancer.

Endorectal MRI and MR spectroscopic imaging of prostate cancer: developing selection criteria for MR-guided focal therapy

PURPOSE

To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy.

MATERIALS AND METHODS

We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm3) dominant intraprostatic tumor foci.

RESULTS

Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio=1.75; 95% confidence interval=1.08 to 2.82; P value=0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm3 of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci.

CONCLUSION

Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm3 of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.

Focal brachytherapy for selected low-risk prostate cancers: a pilot study

PURPOSE

To evaluate the feasibility and the early toxicity of focal brachytherapy in highly selected localized prostate cancer patients.

METHODS AND MATERIALS

Twenty-one patients underwent a focal brachytherapy between February 2010 and March 2012, representing 3.7% of the cases treated by our group during this period. Patient selection was based on (at least) two series of prostate biopsies and a high-resolution MRI. Only patients with very limited and localized tumors, according to strict criteria, were selected for the procedure. The technique used a real-time procedure with the implantation of free (125)I seeds and dynamic dose calculation. The prescribed dose for the focal volume was 145Gy.

RESULTS

The treated volume corresponded to a mean value of 34% of the total prostatic volume (range, 20-48%). For the focal volume, the mean D90 and V100 was 183.2Gy (range, 176-188Gy) and 99.3% (range, 98.8-100%), respectively. The technique was performed in an hour and a half. When compared with a previous cohort treated by whole-prostate brachytherapy, urinary toxicity (International Prostate Symptom Score) was borderline reduced (p = 0.04) at 6 months only, whereas the recovery of the International Index of Erectile Function 5 was better (p = 0.014). The International Continence Score was nil in almost all cases as well as rectal toxicity.

CONCLUSION

Focal treatment by brachytherapy is easily feasible with little acute toxicity. Further investigation is needed to assess the results in terms of tumor control and long-term toxicity.

Does local recurrence of prostate cancer after radiation therapy occur at the site of primary tumor? Results of a longitudinal MRI and MRSI study

PURPOSE

To determine if local recurrence of prostate cancer after radiation therapy occurs at the same site as the primary tumor before treatment, using longitudinal magnetic resonance (MR) imaging and MR spectroscopic imaging to assess dominant tumor location.

METHODS AND MATERIALS

This retrospective study was HIPAA compliant and approved by our Committee on Human Research. We identified all patients in our institutional prostate cancer database (1996 onward) who underwent endorectal MR imaging and MR spectroscopic imaging before radiotherapy for biopsy-proven prostate cancer and again at least 2 years after radiotherapy (n = 124). Two radiologists recorded the presence, location, and size of unequivocal dominant tumor on pre- and postradiotherapy scans. Recurrent tumor was considered to be at the same location as the baseline tumor if at least 50% of the tumor location overlapped. Clinical and biopsy data were collected from all patients.

RESULTS

Nine patients had unequivocal dominant tumor on both pre- and postradiotherapy imaging, with mean pre- and postradiotherapy dominant tumor diameters of 1.8 cm (range, 1-2.2) and 1.9 cm (range, 1.4-2.6), respectively. The median follow-up interval was 7.3 years (range, 2.7-10.8). Dominant recurrent tumor was at the same location as dominant baseline tumor in 8 of 9 patients (89%).

CONCLUSIONS

Local recurrence of prostate cancer after radiation usually occurs at the same site as the dominant primary tumor at baseline, suggesting supplementary focal therapy aimed at enhancing local tumor control would be a rational addition to management.

Multiparametric MRI maps for detection and grading of dominant prostate tumors

PURPOSE

To develop an image-based technique capable of detection and grading of prostate cancer, which combines features extracted from multiparametric MRI into a single parameter map of cancer probability.

MATERIALS AND METHODS

A combination of features extracted from diffusion tensor MRI and dynamic contrast enhanced MRI was used to characterize biopsy samples from 29 patients. Support vector machines were used to separate the cancerous samples from normal biopsy samples and to compute a measure of cancer probability, presented in the form of a cancer colormap. The classification results were compared with the biopsy results and the classifier was tuned to provide the largest area under the receiver operating characteristic (ROC) curve. Based solely on the tuning of the classifier on the biopsy data, cancer colormaps were also created for whole-mount histopathology slices from four radical prostatectomy patients.

RESULTS

An area under ROC curve of 0.96 was obtained on the biopsy dataset and was validated by a "leave-one-patient-out" procedure. The proposed measure of cancer probability shows a positive correlation with Gleason score. The cancer colormaps created for the histopathology patients do display the dominant tumors. The colormap accuracy increases with measured tumor area and Gleason score.

CONCLUSION

Dynamic contrast enhanced imaging and diffusion tensor imaging, when used within the framework of supervised classification, can play a role in characterizing prostate cancer.

Robotic prostate biopsy and its relevance to focal therapy of prostate cancer

Focal therapy is an individualized treatment option for prostate cancer, which destroys localized cancerous tissue but not normal tissue, thus avoiding the morbidities associated with whole-gland therapy. Accurate cancer localization and precise ablation are integral to the success of focal therapy, which remains unproven owing to suboptimal patient selection. Currently, there are no clinical or biopsy features that can identify unifocal prostate cancer and no imaging modality that can accurately diagnose or localize prostate cancer. MRI diagnosis has the best accuracy but high cost and limited access hinder its widespread adoption. New management options, including focal therapy and active surveillance, require prostate biopsy to detect, localize and characterize the cancer. Transrectal prostate biopsy has a high false-negative detection rate, which might be related to an inability to biopsy the anterior and apical part of the prostate or interoperator variation. Transrectal biopsy is also associated with sepsis and bleeding. Robotic transperineal prostate biopsy can overcome the limitations of transrectal procedures. Robotic biopsy is automated with high accuracy, has improved access to the apex and anterior part of the prostate and has low risk of sepsis. Furthermore, it involves only two skin punctures, compared with template-based transperineal prostate biopsy, which can result in multiple wounds. Robotic prostate biopsy fulfills the fundamental needs of focal therapy and might be the platform for future treatment delivery for prostate cancer.

An evaluation of patient selection criteria on predicting progression-free survival after primary focal unilateral nerve-sparing cryoablation for prostate cancer: recommendations for follow up

PURPOSE

Focal cryoablation targets unilateral disease, sparing healthy tissue and the ipsilateral neurovascular bundle. Given half the prostate is spared, proper patient selection is imperative to optimize outcomes. We report focal cryotherapy outcome data and evaluate the accuracy of the 2007 Task Force patient selection criteria at predicting disease recurrence.

MATERIALS AND METHODS

This is a retrospective patient chart review from a single academic institution. Inclusion criterion is having unilateral prostate cancer treated with primary hemicryoablation. Patients were stratified using the Task Force selection criteria. Exclusion criterion is having had past radiation or hormone therapy. Progression-free survival was calculated using follow-up TRUS biopsy (biopsy done with transrectal ultrasound) and serial prostate-specific antigen (PSA) results (Phoenix criteria). Kaplan-Meier curves were constructed and Cox regression analyses performed, comparing outcomes across patient selection cohorts.

RESULTS

From 2002 to 2009, 77 men underwent primary focal cryosurgery: mean age, 69.5 (SD, 6.7) years; median follow-up time, 24 months (range, 0-87 months); mean precryosurgical PSA, 6.5 (SD, 4.9) ng/mL; median Gleason score, 6 (range, 5-8). There were 44, 31, and 2 men who had D'Amico low-, intermediate-, and high-risk disease, respectively. Seventeen men met Focal Task Force Selection Criteria. After treatment, 22 patients underwent prostate biopsy for suspicion of recurrent disease. Of the 22 patients, 10 (45.5%) had confirmed prostate cancer. Of the 10 patients, 2 had ipsilateral disease, 7 had contralateral disease, and 1 had bilateral disease. Overall biochemical and pathological progression-free survival rates were 72.7% and 87%. The cumulative incidence of biochemical disease progression, using the Kaplan-Meier method, was greater than 75% at 3 years for men with more than 2 positive preoperative biopsy cores and greater than 50% at 5 years for men with 2 or less positive preoperative biopsy cores. No survival differences were seen across cohorts. Pretreatment PSA level, pretreatment Gleason score, number positive cores, and total tumor length were associated with disease progression.

CONCLUSIONS

Focal cryotherapy is a promising option for carefully selected patients, although optimization of inclusion criteria is required. Current selection criteria are associated with cancer-free survival. Given no accurate definitions for biochemical failure after focal cryotherapy exist combined with our high biochemical failure rate, mandating 12-month follow-up TRUS biopsy may improve accurate detection of cancer progression. Further follow up will determine optimal patient selection criteria and follow-up protocols for patients undergoing primary focal unilateral nerve-sparing prostate cancer treatment.

[Active surveillance for prostate cancer: usefulness of endorectal MR at 1.5 Tesla with pelvic phased array coil in detecting significant tumors]

PURPOSE

To describe and assess MRI signs of significant tumor in a series of patients who all underwent radical prostatectomy and also fulfilled criteria to choose active surveillance according to French "SurAcaP" protocol.

PATIENTS AND METHODS

The clinical reports of 681 consecutive patients operated on for prostate cancer between 2002 and 2007 were reviewed retrospectively. All patients had endorectal MR (1.5 Tesla) with pelvic phased array coil. (1.5 T erMR PPA). Sixty-one patients (8.9%) fulfilled "SurAcaP" protocol criteria. Preoperative data (MR+core biopsy) were assessed by comparison to whole-mount step section pathology.

RESULTS

85.3% of the 61 patients entering SurAcaP protocol had significant tumor at pathology. (Non Organ Confined Disease (Non OCD)=8.2%, Gleason sum score>6=39.2%). A new exclusion criterion has been assessed: T3MRI±NPS>1 as a predictor tool of significant tumor. ("T3MRI±NPS>1"=Non OCD at MR±number of positive sextants involved in tumor at MR and/or Core Biopsy > to 1). Sensitivity, specificity, PPV, NPV of the criterion "T3MRI±NPS>1" in predicting significant tumor were, respectively: 77%, 33%, 86%, 20%. Adding this criterion to other criteria of the "SurAcaP" protocol could allow the exclusion of all Non OCD, and a decrease in Gleason sum Score>6 rates (20%).

CONCLUSION

Endorectal MR at 1.5 Tesla with pelvic-phased array coil should be considered when selecting patients for active surveillance in the management of prostate cancer. A criterion based upon MR and core biopsy findings, called "T3MR±NSP>1" may represent an exclusion citeria due to its ability to predict significant tumor.

Clinicopathological Strategies to Identify Contralateral Prostate Cancer Involvement in Potential Candidates for Focal Therapy

Objective: To identify the magnitude and possible predictors of contralateral lobe involvement and contralateral extraprostatic extension (EPE) in prostatic biopsy—defined localized unilateral cancers. Patients and Methods: Between January 2005 and August 2009, 1861 patients underwent robotic-assisted radical prostatectomy at the authors’ institution. A total of 1114 had unilateral disease on preoperative biopsy. Final histopathology reports of these patients were reviewed. Results: Of the 1114 patients with unilateral disease on biopsy, 867 (77.9%) had contralateral or bilateral disease on final histopathology. EPE was found in 132 patients (11.9%). Twenty patients (1.8%) had contralateral EPE involvement. High-grade prostatic intraepithelial neoplasm (HGPIN) on biopsy was the significant predictor of contralateral lobe involvement on both univariate ( P = .02; odds ratio [OR] = 1.791) and multivariate analysis ( P = .004; OR = 2.677). Clinical stage T2 was the significant predictor of contralateral EPE on both univariate ( P = .012; OR = 5.250) and multivariate analysis ( P = .007; OR = 8.656). Conclusion: HGPIN on biopsy significantly predicts for contralateral lobe involvement and should be considered an exclusion criterion for focal therapy in prostate cancer patients. Patients with palpable tumor on digital rectal examination should be advised in favor of radical treatment as these patients may harbor more aggressive tumors involving the contralateral side despite the biopsy findings.