Impact of definitive radiotherapy on metabolic response measured with 68Ga-PSMA-PET/CT in patients with intermediate-risk prostate cancer.

PURPOSE: To assess the early metabolic response of the primary tumor using Gallium-68 (68Ga)-labeled-prostate-specific membrane antigen positron emission tomography (68Ga-PSMA-PET/CT), as well as the relationship between PSMA change in the primary tumor and PSA response after definitive radiotherapy (RT), either alone or in combination with androgen deprivation therapy (ADT) in intermediate risk prostate cancer (IR-PCa) patients. METHODS: The clinical data of 71 IR-PCa patients treated with RT alone (36 patients, 50.7%) or RT and ADT (35 patients, 49.3%) were retrospectively analyzed. The difference between pre- and Posttreatment primary tumor PSMA expression and serum PSA values measured 4 months after completion of treatment were compared between treatment arms. Correlation between primary tumor metabolic response and serum PSA changes was analyzed. RESULTS: The median duration between pre- and Posttreatment 68Ga-PSMA-PET/CT for the entire patient population was 6.9 months (range, 5.6-8.4 months), and it was similar in both treatment arms. A decrease in primary tumor maximum standardized uptake value (SUVmax) was seen in 66 patients (93.0%), with a median value of 61.2%, which is significantly lower in patients undergoing RT alone than those undergoing RT and ADT (45.1 ± 30.6% vs. 59.1 ± 24.7%; p = 0.004). The complete metabolic response rate was significantly higher in patients undergoing RT and ADT than those treated with RT alone (40% vs. 0%; p < 0.001). Although moderate and positive correlation between pretreatment SUVmax and oosttreatment SUVmax was observed, there was no significant correlation between SUV change and PSA change. For patients treated with RT and ADT, posttreatment SUVmax was significantly lower and SUV change was significantly higher in patients with PSA nadir than in those without. CONCLUSIONS: Our preliminary results show that RT, with or without ADT, significantly reduces primary tumor SUVmax and serum PSA levels. Nonetheless, our findings indicate that early treatment response using 68Ga-PSMA-PET/CT is not feasible for those treated with RT alone, and it may only be useful in better distinguishing patients with and without PSA nadir for those who received both RT and ADT.

PIK3/Akt/mTOR pathway alterations in metastatic castration-sensitive prostate cancer.

BACKGROUND: Alterations in the PIK3/Akt/mTOR pathway are commonly seen in metastatic castration-sensitive prostate cancer (mCSPC), however their role in outcomes is unknown. We aim to evaluate the prognostic significance as well as the genetic landscape of PIK3/Akt/mTOR pathway alteration in mCSPC. METHODS: Fourhundred and seventy-two patients with mCSPC were included who underwent next generation sequencing. PIK3/Akt/mTor pathway alterations were defined as mutations in Akt1, mTOR, PIK3CA, PIK3CB, PIK3R1, PTEN, TSC1, and TSC2. Endpoints of interests were radiographic progression-free survival (rPFS), time to development of castration resistant prostate cancer (tdCRPC), and overall survival (OS). Kaplan-Meier analysis was performed and Cox regression hazard ratios (HR) were calculated. RESULTS: One hundred and fifty-two (31.9%) patients harbored a PIK3/Akt/mTOR pathway alteration. Median rPFS and tdCRPC were 23.7 and 21.0 months in PIK3/Akt/mTOR altered compared to 32.8 (p = 0.08) and 32.1 months (p = 0.002) in wildtype tumors. On multivariable analysis PIK3/Akt/mTOR pathway alterations were associated with tdCRPC (HR 1.43, 95% CI, 1.05-1.94, p = 0.02), but not rPFS [Hazard ratio (HR) 1.20, 95% confidence interval (CI), 0.90-1.60, p = 0.21]. PIK3/Akt/mTOR pathway alterations were more likely to be associated with concurrent mutations in TP53 (40% vs. 28%, p = 0.01) and TMPRSS2-ERG (37% vs. 26%, p = 0.02) than tumors without PIK3/Akt/mTOR pathway alterations. Concurrent mutations were typically associated with shorter median times to rPFS and tdCRPC. DAVID analysis showed p53 signaling and angiogenesis pathways were enriched in PIK3/Akt/mTOR pathway altered tumors while beta-catenin binding and altered BRCA pathway were enriched in PIK3/Akt/mTOR pathway wildtype tumors. CONCLUSIONS: PIK3/Akt/mTOR pathway alterations were common in mCSPC and associated with poorer prognosis. The genetic landscape of PIK3/Akt/mTOR pathway altered tumors differed from wildtype tumors. Additional studies are needed to better understand and target the PIK3/Akt/mTOR pathway in mCSPC.

Evaluation of Treatment Outcomes of Prostate Cancer Patients With Lymph Node Metastasis Treated With Definitive Radiotherapy: Comparative Analysis of PSMA PET/CT and Conventional Imaging.

PURPOSE: We investigated the impact of prostate-specific membrane antigen (PSMA) PET/CT compared with conventional imaging on treatment outcomes for node-positive prostate cancer (PCa) patients who underwent androgen deprivation therapy (ADT) and external radiotherapy (RT). PATIENTS AND METHODS: A multicentric, retrospective study recruited patients with node-positive PCa patients who underwent conventional radiological evaluation or PSMA PET/CT and received ADT and RT at 3 hospitals from 2009 to 2021 were enrolled. Patients underwent prostate and pelvis RT, accompanied by a minimum of 6 months of ADT. The primary endpoints were progression-free survival (PFS) and PCa-specific survival (PCSS). Cox regression analyzed the association of survival with potential prognostic factors, whereas logistic regression identified the predictors of bone and lymph node metastasis. RESULTS: The median follow-up time was 64.0 months. The majority of patients (64.1%) underwent PSMA PET/CT for staging. The 5-year rates of PFS and PCSS were 63.7% and 83.7%, respectively. Disease progression was observed in 90 patients (36.3%). In multivariable analysis, ADT duration of less than 24 months and post-RT prostate-specific antigen (PSA) nadir were prognostic for PFS. Early clinical T stage and PSMA PET/CT predicted better PCSS. Patients staged with PSMA PET/CT had exhibited significantly higher 5-year PCSS rates than compared with those staged with conventional imaging (95.1% vs 76.9%; P = 0.01). Shorter ADT duration and higher PSA levels after RT independently predicted bone metastasis in multivariable logistic regression. Advanced T stage, shorter ADT duration, and higher PSA levels after neoadjuvant ADT predicted nonregional lymph node recurrence. CONCLUSIONS: ADT with pelvis RT is an effective treatment option for node-positive PCa patients. The PSMA PET/CT outperformed conventional imaging in PCSS, emphasizing the importance of precise clinical staging for patients undergoing definitive RT.

Genomic Determinants Associated with Modes of Progression and Patterns of Failure in Metachronous Oligometastatic Castration-sensitive Prostate Cancer.

BACKGROUND AND OBJECTIVE: Oligometastatic castration-sensitive prostate cancer (omCSPC) represents an early state in the progression of metastatic disease for which patients experience better outcomes in comparison to those with higher disease burden. Despite the generally more indolent nature, there is still much heterogeneity, with some patients experiencing a more aggressive clinical course unexplained by clinical features alone. Our aim was to investigate correlation of tumor genomics with the mode of progression (MOP) and pattern of failure (POF) following first treatment (metastasis-directed and/or systemic therapy) for omCSPC. METHODS: We performed an international multi-institutional retrospective study of men treated for metachronous omCSPC who underwent tumor next-generation sequencing with at least 1 yr of follow-up after their first treatment. Descriptive MOP and POF results are reported with respect to the presence of genomic alterations in pathways of interest. MOP was defined as class I, long-term control (LTC; no radiographic progression at last follow-up), class II, oligoprogression (1-3 lesions), or class III, polyprogression (≥4 lesions). POF included the location of lesions at first failure. Genomic pathways of interest included TP53, ATM, RB1, BRCA1/2, SPOP, and WNT (APC, CTNNB1, RNF43). Genomic associations with MOP/POF were compared using χ2 tests. Exploratory analyses revealed that the COSMIC mutational signature and differential gene expression were also correlated with MOP/POF. Overall survival (OS) was calculated via the Kaplan-Meier method from the time of first failure. KEY FINDINGS AND CLINICAL IMPLICATIONS: We included 267 patients in our analysis; the majority had either one (47%) or two (30%) metastatic lesions at oligometastasis. The 3-yr OS rate was significantly associated with MOP (71% for polyprogression vs 91% for oligoprogression; p = 0.005). TP53 mutation was associated with a significantly lower LTC rate (27.6% vs 42.3%; p = 0.04) and RB1 mutation was associated with a high rate of polyprogression (50% vs 19.9%; p = 0.022). Regarding POF, bone failure was significantly more common with tumors harboring TP53 mutations (44.8% vs25.9%; p = 0.005) and less common with SPOP mutations (7.1% vs 31.4%; p = 0.007). Visceral failure was more common with tumors harboring either WNT pathway mutations (17.2% vs 6.8%, p = 0.05) or SPOP mutations (17.9% vs 6.3%; p = 0.04). Finally, visceral and bone failures were associated with distinct gene-expression profiles. CONCLUSIONS AND CLINICAL IMPLICATIONS: Tumor genomics provides novel insight into MOP and POF following treatment for metachronous omCSPC. Patients with TP53 and RB1 mutations have a higher likelihood of progression, and TP53, SPOP, and WNT pathway mutations may have a role in metastatic organotropism. PATIENT SUMMARY: We evaluated cancer progression after a first treatment for metastatic prostate cancer with up to five metastases. We found that mutations in certain genes were associated with the location and extent of further metastasis in these patients.

TNIK Inhibition Sensitizes TNIK-Overexpressing Lung Squamous Cell Carcinoma to Radiotherapy.

Most patients with lung squamous cell carcinoma (LSCC) undergo chemotherapy, radiotherapy, and adjuvant immunotherapy for locally advanced disease. The efficacy of these treatments is still limited because of dose-limiting toxicity or locoregional recurrence. New combination approaches and targets such as actionable oncogenic drivers are needed to advance treatment options for patients with LSCC. Moreover, other options for chemotherapy-ineligible patients are limited. As such, there is a critical need for the development of selective and potent chemoradiosensitizers for locally advanced LSCC. In this study, we investigated inhibiting TRAF2- and NCK-interacting protein kinase (TNIK), which is amplified in 40% of patients with LSCC, as a strategy to sensitize LSCC tumors to chemotherapy and radiotherapy. Employing a range of human LSCC cell lines and the TNIK inhibitor NCB-0846, we investigated the potential of TNIK as a chemo- and radiosensitizing target with in vitro and in vivo preclinical models. The combination of NCB-0846 with cisplatin or etoposide was at best additive. Interestingly, pre-treating LSCC cells with NCB-0846 prior to ionizing radiation (IR) potentiated the cytotoxicity of IR in a TNIK-specific fashion. Characterization of the radiosensitization mechanism suggested that TNIK inhibition may impair the DNA damage response and promote mitotic catastrophe in irradiated cells. In a subcutaneous xenograft in vivo model, pretreatment with NCB-0846 significantly enhanced the efficacy of IR and caused elevated necrosis in TNIKhigh LK2 tumors but not TNIKlow KNS62 tumors. Overall, these results indicate that TNIK inhibition may be a promising strategy to increase the efficacy of radiotherapy in patients with LSCC with high TNIK expression.

Prostate-Specific Membrane Antigen PET Response Associates with Metastasis-Free Survival After Stereotactic Ablative Radiation in Oligometastatic Prostate Cancer.

Purpose: Emerging data suggest that metastasis-directed therapy (MDT) improves outcomes in patients with oligometastatic castration-sensitive prostate cancer (omCSPC). Prostate-specific membrane antigen positron emission tomography (PSMA-PET) can detect occult metastatic disease, and PSMA response has been proposed as a biomarker for treatment response. Herein, we identify and validate a PSMA-PET biomarker for metastasis-free survival (MFS) following MDT in omCSPC. Methods and Materials: We performed an international multi-institutional retrospective study of patients with omCSPC, defined as ≤3 lesions, treated with metastasis-directed stereotactic ablative radiation who underwent PSMA-PET/computed tomography (CT) before and after (median, 6.2 months; range, 2.4-10.9 months) treatment. Pre- and post-MDT PSMA-PET/CT maximum standardized uptake value (SUVmax) was measured for all lesions, and PSMA response was defined as the percent change in SUVmax of the least responsive lesion. PSMA response was both evaluated as a continuous variable and dichotomized into PSMA responders, with a complete/partial response (at least a 30% reduction in SUVmax), and PSMA nonresponders, with stable/progressive disease (less than a 30% reduction in SUVmax). PSMA response was correlated with conventional imaging-defined metastasis-free survival (MFS) via Kaplan-Meier and Cox regression analysis. Results: A total of 131 patients with 261 treated metastases were included in the analysis, with a median follow-up of 29 months (IQR, 18.5-41.3 months). After stereotactic ablative radiation, 70.2% of patients were classified as PSMA responders. Multivariable analysis demonstrated that PSMA response as a continuous variable was associated with a significantly worse MFS (hazard ratio = 1.003; 95% CI, 1.001-1.006; P = .016). Patients classified as PSMA responders were found to have a significantly improved median MFS of 39.9 versus 12 months (P = .001) compared with PSMA nonresponders. Our study is limited as it is a retrospective review of a heterogenous population. Conclusions: After stereotactic ablative radiation, PSMA-PET response appears to be a radiographic biomarker that correlates with MFS in omCSPC. This approach holds promise for guiding clinical management of omCSPC and should be validated in a prospective setting.

Multi-institutional Analysis of Metastasis-directed Therapy with or Without Androgen Deprivation Therapy in Oligometastatic Castration-sensitive Prostate Cancer.

BACKGROUND: Metastasis-directed therapy (MDT) is increasingly being used in oligometastatic castration-sensitive prostate cancer (omCSPC). However, it is currently unclear how to optimally integrate MDT with the standard of care of systemic hormonal therapy. OBJECTIVE: To report long-term outcomes of MDT alone versus MDT and a defined course of androgen deprivation therapy (ADT) in omCSPC. DESIGN, SETTING, AND PARTICIPANTS: Here, a multicenter, international retrospective cohort of omCSPC as defined by conventional imaging was reported. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Biochemical progression-free survival (bPFS), distant progression-free survival (dPFS), and combined biochemical or distant progression-free survival (cPFS) were evaluated with Kaplan-Meier and multivariable Cox proportional hazard regression models. RESULTS AND LIMITATIONS: A total of 263 patients were included, 105 with MDT + ADT and 158 with MDT alone. The majority of patients had metachronous disease (90.5%). Five-year bPFS, dPFS, and cPFS were, respectively, 24%, 41%, and 19% in patients treated with MDT + ADT and 11% (hazard ratio [HR] 0.48, 95% confidence interval [CI] 0.36-0.64), 29% (HR 0.56, 95% CI 0.40-0.78), and 9% (HR 0.50, 95% CI 0.38-0.67) in patients treated with MDT alone. On a multivariable analysis adjusting for pretreatment variables, the use of ADT was associated with improved bPFS (HR 0.43, p < 0.001), dPFS (HR 0.45, p = 0.002), and cPFS (HR 0.44, p < 0.001). CONCLUSIONS: In this large multi-institutional report, the addition of concurrent ADT to MDT appears to improve time to prostate-specific antigen progression and distant recurrence, noting that about 10% patients had durable control with MDT alone. Ongoing phase 3 studies will help further define treatment options for omCSPC. PATIENT SUMMARY: Here, we report a large retrospective review evaluating the outcomes of metastasis-directed therapy with or without a limited course of androgen deprivation for patients with oligometastatic castration-sensitive prostate cancer. This international multi-institutional review demonstrates that the addition of androgen deprivation therapy to metastasis-directed therapy (MDT) improves progression-free survival. While a proportion of patients appear to have long-term disease control with MDT alone, further work in biomarker discovery is required to better identify which patients would be appropriate for de-escalated therapy.

TNIK inhibition sensitizes TNIK-overexpressing lung squamous cell carcinoma to radiotherapy.

Most patients with lung squamous cell carcinoma (LSCC) undergo chemotherapy, radiotherapy, and adjuvant immunotherapy for locally advanced disease. The efficacy of these treatments is still limited due to dose-limiting toxicity or locoregional recurrence. New combination approaches and targets such as actionable oncogenic drivers are needed to advance treatment options for LSCC patients. Moreover, other options for chemotherapy-ineligible patients are also limited. As such there is a critical need for the development of selective and potent chemoradiosensitizers for locally advanced LSCC. Here, we investigated inhibiting TRAF2 and NCK-interacting protein kinase (TNIK), which is amplified in 40% of LSCC patients, as a strategy to sensitize LSCC tumors to chemo- and radiotherapy. Employing a range of human LSCC cell lines and the TNIK inhibitor NCB-0846, we investigated the potential of TNIK as a chemo- and radiosensitizing target with in vitro and in vivo preclinical models. The combination of NCB-0846 with cisplatin or etoposide was at best additive. Interestingly, pre-treating LSCC cells with NCB-0846 prior to ionizing radiation (IR) potentiated the cytotoxicity of IR in a TNIK-specific fashion. Characterization of the radiosensitization mechanism suggested that TNIK inhibition may impair the DNA damage response and promote mitotic catastrophe in irradiated cells. In a subcutaneous xenograft in vivo model, pretreatment with NCB-0846 significantly enhanced the efficacy of IR and caused elevated necrosis in TNIKhigh LK2 tumors but not TNIKlow KNS62 tumors. Overall, these results indicate that TNIK inhibition may be a promising strategy to increase the efficacy of radiotherapy in LSCC patients with high TNIK expression.

Prognostic Significance of Immune Cell Infiltration in Muscle-invasive Bladder Cancer Treated with Definitive Chemoradiation: A Secondary Analysis of RTOG 0524 and RTOG 0712.

Chemoradiation therapy (CRT) is a treatment for muscle-invasive bladder cancer (MIBC). Using a novel transcriptomic profiling panel, we validated prognostic immune biomarkers to CRT using 70 pretreatment tumor samples from prospective trials of MIBC (NRG/RTOG 0524 and 0712). Disease-free survival (DFS) and overall survival (OS) were estimated via the Kaplan-Meier method and stratified by genes correlated with immune cell activation. Cox proportional-hazards models were used to assess group differences. Clustering of gene expression profiles revealed that the cluster with high immune cell content was associated with longer DFS (hazard ratio [HR] 0.53, 95% confidence interval [CI] 0.26-1.10; p = 0.071) and OS (HR 0.48, 95% CI 0.24-0.97; p = 0.040) than the cluster with low immune cell content. Higher expression of T-cell infiltration genes (CD8A and ICOS) was associated with longer DFS (HR 0.40, 95% CI 0.21-0.75; p = 0.005) and OS (HR 0.49, 95% CI 0.25-0.94; p = 0.033). Higher IDO1 expression (IFNγ signature) was also associated with longer DFS (HR 0.44, 95% CI 0.24-0.88; p = 0.021) and OS (HR 0.49, 95% CI 0.24-0.99; p = 0.048). These findings should be validated in prospective CRT trials that include biomarkers, particularly for trials incorporating immunotherapy for MIBC. PATIENT SUMMARY: We analyzed patient samples from two clinical trials (NRG/RTOG 0524 and 0712) of chemoradiation for muscle-invasive bladder cancer using a novel method to assess immune cells in the tumor microenvironment. Higher expression of genes associated with immune activation and high overall immune-cell content were associated with better disease-free survival and overall survival for patients treated with chemoradiation.

Cardiovascular Mortality and Duration of Androgen Deprivation in Locally Advanced Prostate Cancer: Long-term Update of NRG/RTOG 9202.

BACKGROUND: Androgen deprivation therapy (ADT) has been associated with coronary heart disease and myocardial infarction (MI) in prostate cancer patients, but controversy persists regarding its effects on cardiovascular mortality (CVM). OBJECTIVE: We assessed the long-term relationship between ADT and CVM in a prostate cancer randomized trial (NRG Oncology/Radiation Therapy Oncology Group 9202). DESIGN, SETTING, AND PARTICIPANTS: From 1992 to 1995, 1554 men with locally advanced prostate cancer (T2c-T4, prostate-specific antigen <150 ng/ml) received radiotherapy with 4 mo (short-term [STADT]) versus 28 mo (longer-term [LTADT]) of ADT. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Using the Fine-Gray and Cox regression models, the relationship between ADT and mortality was evaluated. RESULTS AND LIMITATIONS: With a median follow-up of 19.6 yr, LTADT was associated with improved overall survival (OS) versus STADT (adjusted hazard ratio [HR] 0.88; p = 0.03) and prostate cancer survival (subdistribution HR [sHR] 0.70, p = 0.003). Comparing LTADT with STADT, prostate cancer mortality improved by 6.0% (15.6% [95% confidence interval 13.0-18.3%] vs 21.6% [18.6-24.7%]) at 15 yr, while CVM increased by 2.2% (14.9% [12.4-17.6%] vs 12.7% [10.4-15.3%]). In multivariable analyses, LTADT was not associated with increased CVM versus STADT (sHR 1.22 [0.93-1.59]; p = 0.15). An association between LTADT and MI death was detected (sHR 1.58 [1.00-2.50]; p = 0.05), particularly in patients with prevalent cardiovascular disease (CVD; sHR 2.54 [1.16-5.58]; p = 0.02). CONCLUSIONS: With 19.6 yr of follow-up, LTADT was not significantly associated with increased CVM in men with locally advanced prostate cancer. Patients may have increased MI mortality with LTADT, particularly those with baseline CVD. Overall, there remained a prostate cancer mortality benefit and no OS detriment with LTADT. PATIENT SUMMARY: In a long-term analysis of a large randomized prostate cancer trial, radiation with 28 mo of hormone therapy did not increase the risk of cardiovascular death significantly versus 4 mo of hormone therapy. Future studies are needed for patients with pre-existing heart disease, who may have an increased risk of myocardial infarction death with longer hormone use.

External Validation of a Digital Pathology-based Multimodal Artificial Intelligence Architecture in the NRG/RTOG 9902 Phase 3 Trial.

BACKGROUND: Accurate risk stratification is critical to guide management decisions in localized prostate cancer (PCa). Previously, we had developed and validated a multimodal artificial intelligence (MMAI) model generated from digital histopathology and clinical features. Here, we externally validate this model on men with high-risk or locally advanced PCa treated and followed as part of a phase 3 randomized control trial. OBJECTIVE: To externally validate the MMAI model on men with high-risk or locally advanced PCa treated and followed as part of a phase 3 randomized control trial. DESIGN, SETTING, AND PARTICIPANTS: Our validation cohort included 318 localized high-risk PCa patients from NRG/RTOG 9902 with available histopathology (337 [85%] of the 397 patients enrolled into the trial had available slides, of which 19 [5.6%] failed due to poor image quality). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Two previously locked prognostic MMAI models were validated for their intended endpoint: distant metastasis (DM) and PCa-specific mortality (PCSM). Individual clinical factors and the number of National Comprehensive Cancer Network (NCCN) high-risk features served as comparators. Subdistribution hazard ratio (sHR) was reported per standard deviation increase of the score with corresponding 95% confidence interval (CI) using Fine-Gray or Cox proportional hazards models. RESULTS AND LIMITATIONS: The DM and PCSM MMAI algorithms were significantly and independently associated with the risk of DM (sHR [95% CI] = 2.33 [1.60-3.38], p < 0.001) and PCSM, respectively (sHR [95% CI] = 3.54 [2.38-5.28], p < 0.001) when compared against other prognostic clinical factors and NCCN high-risk features. The lower 75% of patients by DM MMAI had estimated 5- and 10-yr DM rates of 4% and 7%, and the highest quartile had average 5- and 10-yr DM rates of 19% and 32%, respectively (p < 0.001). Similar results were observed for the PCSM MMAI algorithm. CONCLUSIONS: We externally validated the prognostic ability of MMAI models previously developed among men with localized high-risk disease. MMAI prognostic models further risk stratify beyond the clinical and pathological variables for DM and PCSM in a population of men already at a high risk for disease progression. This study provides evidence for consistent validation of our deep learning MMAI models to improve prognostication and enable more informed decision-making for patient care. PATIENT SUMMARY: This paper presents a novel approach using images from pathology slides along with clinical variables to validate artificial intelligence (computer-generated) prognostic models. When implemented, clinicians can offer a more personalized and tailored prognostic discussion for men with localized prostate cancer.

Stereotactic ablative radiation therapy in metastatic prostate cancer.

PURPOSE OF REVIEW: The evolving role of stereotactic ablative radiation therapy (SABR) as metastasis-directed therapy (MDT) for oligometastatic prostate cancer (omPCa) will be discussed. RECENT FINDINGS: Oligometastatic disease (OMD) is an intermediate state between localized and wide-spread malignant disease. OMD has recently been spotlighted given the increasing demonstration of clinical benefit from local therapies despite presence of metastatic disease and allure of the curative potential of MDT in select cases. Among the different forms of MDT, SABR has rapidly become a widely adopted treatment modality. Significant efforts in this space have focused on omPCa, owing to its relatively indolent biology, presence of a sensitive and specific serum biomarker and recent advances in molecular imaging. While most studies have evaluated the role of SABR MDT in hormone sensitive omPCa, new emerging clinical data also suggests benefits of SABR MDT for even castration-resistant disease. SUMMARY: Treating omPCa with SABR MDT appears to generate an efficacy signal with minimal morbidity across both hormone-sensitive and castration-resistant disease. However, additional definitive omPCa trial data are needed. Future research efforts should investigate biomarkers for this heterogeneous disease space and the role of SABR MDT in combination with systemic agents to improve upon standard of care treatments.

Salvage Therapy for Prostate Cancer: AUA/ASTRO/SUO Guideline Part III: Salvage Therapy After Radiotherapy or Focal Therapy, Pelvic Nodal Recurrence and Oligometastasis, and Future Directions.

PURPOSE: The summary presented herein covers recommendations on salvage therapy for recurrent prostate cancer intended to facilitate care decisions and aid clinicians in caring for patients who have experienced a recurrence following prior treatment with curative intent. This is Part III of a three-part series focusing on evaluation and management of suspected non-metastatic recurrence after radiotherapy (RT) and focal therapy, evaluation and management of regional recurrence, management for molecular imaging metastatic recurrence, and future directions. Please refer to Part I for discussion of treatment decision-making and Part II for discussion of treatment delivery for non-metastatic biochemical recurrence (BCR) after radical prostatectomy (RP). MATERIALS AND METHODS: The systematic review that informs this Guideline was based on searches in Ovid MEDLINE (1946 to July 21, 2022), Cochrane Central Register of Controlled Trials (through August 2022), and Cochrane Database of Systematic Reviews (through August 2022). Update searches were conducted on July 26, 2023. Searches were supplemented by reviewing electronic database reference lists of relevant articles. RESULTS: In a collaborative effort between AUA, ASTRO, and SUO, the Salvage Therapy for Prostate Cancer Guideline Panel developed evidence- and consensus-based guideline statements to provide guidance for the care of patients who experience BCR after initial definitive local therapy for clinically localized disease. CONCLUSIONS: Continuous and deliberate efforts for multidisciplinary care in prostate cancer will be required to optimize and improve the oncologic and functional outcomes of patients treated with salvage therapies in the future.

Salvage Therapy for Prostate Cancer: AUA/ASTRO/SUO Guideline Part I: Introduction and Treatment Decision-Making at the Time of Suspected Biochemical Recurrence after Radical Prostatectomy.

PURPOSE: The summary presented herein covers recommendations on salvage therapy for recurrent prostate cancer intended to facilitate care decisions and aid clinicians in caring for patients who have experienced a recurrence following prior treatment with curative intent. This is Part I of a three-part series focusing on treatment decision-making at the time of suspected biochemical recurrence (BCR) after radical prostatectomy (RP). Please refer to Part II for discussion of treatment delivery for non-metastatic BCR after RP and Part III for discussion of evaluation and management of recurrence after radiotherapy (RT) and focal therapy, regional recurrence, and oligometastasis. MATERIALS AND METHODS: The systematic review that informs this Guideline was based on searches in Ovid MEDLINE (1946 to July 21, 2022), Cochrane Central Register of Controlled Trials (through August 2022), and Cochrane Database of Systematic Reviews (through August 2022). Update searches were conducted on July 26, 2023. Searches were supplemented by reviewing electronic database reference lists of relevant articles. RESULTS: In a collaborative effort between AUA, ASTRO, and SUO, the Salvage Therapy for Prostate Cancer Panel developed evidence- and consensus-based statements to provide guidance for the care of patients who experience BCR after initial definitive local therapy for clinically localized disease. CONCLUSIONS: Advancing work in the area of diagnostic tools (particularly imaging), biomarkers, radiation delivery, and biological manipulation with the evolving armamentarium of therapeutic agents will undoubtedly present new opportunities for patients to experience long-term control of their cancer while minimizing toxicity.

Salvage Therapy for Prostate Cancer: AUA/ASTRO/SUO Guideline Part II: Treatment Delivery for Non-metastatic Biochemical Recurrence After Primary Radical Prostatectomy.

PURPOSE: The summary presented herein covers recommendations on salvage therapy for recurrent prostate cancer intended to facilitate care decisions and aid clinicians in caring for patients who have experienced a recurrence following prior treatment with curative intent. This is Part II of a three-part series focusing on treatment delivery for non-metastatic biochemical recurrence (BCR) after primary radical prostatectomy (RP). Please refer to Part I for discussion of treatment decision-making and Part III for discussion of evaluation and management of recurrence after radiotherapy (RT) and focal therapy, regional recurrence, and oligometastasis. MATERIALS AND METHODS: The systematic review that informs this Guideline was based on searches in Ovid MEDLINE (1946 to July 21, 2022), Cochrane Central Register of Controlled Trials (through August 2022), and Cochrane Database of Systematic Reviews (through August 2022). Update searches were conducted on July 26, 2023. Searches were supplemented by reviewing electronic database reference lists of relevant articles. RESULTS: In a collaborative effort between AUA, ASTRO, and SUO, the Salvage Therapy for Prostate Cancer Panel developed evidence- and consensus-based guideline statements to provide guidance for the care of patients who experience BCR after initial definitive local therapy for clinically localized disease. CONCLUSIONS: Optimizing and personalizing the approach to salvage therapy remains an ongoing area of work in the field of genitourinary oncology and represents an area of research and clinical care that requires well-coordinated, multi-disciplinary efforts.

A Longitudinal Metagenomic Comparative Analysis of Oral Microbiome Shifts in Patients Receiving Proton Radiation versus Photon Radiation for Head and Neck Cancer.

Introduction: Due to the radiation-sparing effects on salivary gland acini, changes in the composition of the oral microbiome may be a driver for improved outcomes in patients receiving proton radiation, with potentially worse outcomes in patients exposed to photon radiation therapy. To date, a head-to-head comparison of oral microbiome changes at a metagenomic level with longitudinal sampling has yet to be performed in these patient cohorts. Methods and Materials: To comparatively analyze oral microbiome shifts during head and neck radiation therapy, a prospective pilot cohort study was performed at the Maryland Proton Treatment Center and the University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center. A longitudinal metagenomic comparative analysis of oral microbiome shifts was performed at three time points (pre-radiation, during radiation, and immediately post-radiation). Head and neck cancer patients receiving proton radiation (n = 4) were compared to photon radiation (n = 4). Additional control groups included healthy age- and sex-matched controls (n = 5), head and neck cancer patients who never received radiation therapy (n = 8), and patients with oral inflammatory disease (n = 3). Results: Photon therapy patients presented with lower microbial alpha diversity at all timepoints, and there was a trend towards reduced species richness as compared with proton therapy. Healthy controls and proton patients exhibited overall higher and similar diversity. A more dysbiotic state was observed in patients receiving photon therapy as compared to proton therapy, in which oral microbial homeostasis was maintained. Mucositis was observed in 3/4 photon patients and was not observed in any proton patients during radiation therapy. The bacterial de novo pyrimidine biosynthesis pathway and the nitrate reduction V pathway were comparatively higher following photon exposure. These functional changes in bacterial metabolism may suggest that photon exposure produces a more permissive environment for the proliferation of pathogenic bacteria. Conclusion: Oral microbiome dysbiosis in patients receiving photon radiation may be associated with increased mucositis occurrence. Proton radiation therapy for head and neck cancer demonstrates a safer side effect profile in terms of oral complications, oral microbiome dysbiosis, and functional metabolic status.

Identification of a Predictive Genomic Biomarker for Prostate-directed Therapy in Synchronous Low-volume Metastatic Castration-sensitive Prostate Cancer.

BACKGROUND: Standard of care management for synchronous metastatic castration-sensitive prostate cancer (mCSPC) includes androgen deprivation therapy with a second-generation antiandrogen therapy and/or docetaxel. Recently, randomized data have demonstrated that prostate-directed therapy (PDT) is associated with an improvement in overall survival (OS) among patients with low-volume metastatic disease. Tumor genomics represents an additional dimension to define the clinical trajectory of patients with mCSPC. OBJECTIVE: To evaluate a high-risk (HiRi) genomic signature to predict the benefit from PDT. DESIGN, SETTING, AND PARTICIPANTS: We performed a single-institution retrospective review of men with synchronous low-volume mCSPC who underwent DNA panel sequencing of their tumor. Patients were classified according to the presence of HiRi mutation including pathogenic mutations in TP53, ATM, BRCA1, BRCA2, or Rb1. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary endpoint was to determine the effect of PDT on OS in patients with and without a HiRi mutation. A survival analysis was performed with the Kaplan-Meier method compared with log-rank test and multivariable Cox regression. The interaction between HiRi mutation and PDT was evaluated. RESULTS AND LIMITATIONS: A total of 101 patients with synchronous low-volume CSPC were included with a median follow-up of 44 mo. Approximately half of patients were found to have a HiRi pathogenic mutation (49%). Patients with HiRi mutations demonstrated median OS of 73 versus 66.8 mo (p = 0.3) for no PDT versus PDT. Conversely, patients without a HiRi mutation demonstrated a significant improvement in OS of 60 versus 105.3 mo (p < 0.001) for no PDT versus PDT. The p value for interaction for OS between PDT and HiRi mutation was statistically significant (p < 0.001). Limitations include the retrospective nature of the study. CONCLUSIONS: Here, we have identified a HiRi genomic biomarker that appears predictive for the lack of benefit from PDT in men with synchronous low-volume mCSPC. Further work validating these results is warranted. PATIENT SUMMARY: In this report, we evaluated a high-risk genomic biomarker to predict the benefit from prostate-directed therapy for men with synchronous low-volume metastatic castration-sensitive prostate cancer. We found that men without a high-risk mutation appear to experience a greater clinical benefit from prostate-directed therapy than those with a high-risk mutation.

TP53 structure-function relationships in metastatic castrate-sensitive prostate cancer and the impact of APR-246 treatment.

PURPOSE: Despite well-informed work in several malignancies, the phenotypic effects of TP53 mutations in metastatic castration-sensitive prostate cancer (mCSPC) progression and metastasis are not clear. We characterized the structure-function and clinical impact of TP53 mutations in mCSPC. PATIENTS AND METHODS: We performed an international retrospective review of men with mCSPC who underwent next-generation sequencing and were stratified according to TP53 mutational status and metastatic burden. Clinical outcomes included radiographic progression-free survival (rPFS) and overall survival (OS) evaluated with Kaplan-Meier and multivariable Cox regression. We also utilized isogenic cancer cell lines to assess the effect of TP53 mutations and APR-246 treatment on migration, invasion, colony formation in vitro, and tumor growth in vivo. Preclinical experimental observations were compared using t-tests and ANOVA. RESULTS: Dominant-negative (DN) TP53 mutations were enriched in patients with synchronous (vs. metachronous) (20.7% vs. 6.3%, p < 0.01) and polymetastatic (vs. oligometastatic) (14.4% vs. 7.9%, p < 0.01) disease. On multivariable analysis, DN mutations were associated with worse rPFS (hazards ratio [HR] = 1.97, 95% confidence interval [CI]: 1.31-2.98) and overall survival [OS] (HR = 2.05, 95% CI: 1.14-3.68) compared to TP53 wild type (WT). In vitro, 22Rv1 TP53 R175H cells possessed stronger migration, invasion, colony formation ability, and cellular movement pathway enrichment in RNA sequencing analysis compared to 22Rv1 TP53 WT cells. Treatment with APR-246 reversed the effects of TP53 mutations in vitro and inhibited 22Rv1 TP53 R175H tumor growth in vivo in a dosage-dependent manner. CONCLUSIONS: DN TP53 mutations correlated with worse prognosis in prostate cancer patients and higher metastatic potential, which could be counteracted by APR-246 treatment suggesting a potential future therapeutic avenue.