Stereotactic Body Radiotherapy for Renal Cell Carcinoma-A Review of Use in the Primary, Cytoreductive and Oligometastatic Settings.

Renal cell carcinoma (RCC) has been increasing in incidence by around 1.5% per year for several years. However, the mortality rate has been decreasing by 1.6% per year, and this can be attributed to stage migration and improvements in treatment. One treatment modality that has emerged in recent years is stereotactic body radiotherapy (SBRT), which is an advanced radiotherapy technique that allows the delivery of high-dose radiation to the tumor while minimizing doses to the organs at risk. SBRT has developed a role in the treatment of early-stage, oligometastatic and oligoprogressive RCC. In localized disease, phase II trials and meta-analyses have shown that SBRT provides a very high probability of long-term local control with a low risk of severe late toxicity. In oligometastatic (OMD) RCC, the same level of evidence has similarly shown good local control and minimal toxicity. SBRT could also delay the necessity to start or switch systemic treatments. Medical societies have started to incorporate SBRT in their guidelines in the treatment of localized disease and OMD. A possible future role of SBRT involves cytoreduction. It is theorized that SBRT can lower tumor burden and enhance immune-related response, but it cannot be recommended until the results of the phase II trials are published.

Radiotherapy Improves Survival in NSCLC After Oligoprogression on Immunotherapy: A Cohort Study.

Introduction: The patterns of oligoprogression after first-line immune checkpoint inhibitors (ICIs) for metastatic NSCLC are yet to be well established. An increasing volume of data suggests that directed radiotherapy improves survival outcomes in patients with progression after ICIs. Methods: A retrospective cohort study was performed on patients with metastatic NSCLC who had completed first-line programmed death-(ligand) 1 inhibitor therapy with or without chemotherapy at two high-volume cancer centers. We sought to characterize the frequency and location of oligoprogression and determine the overall survival (OS) after radiotherapy in this population. Results: A total of 159 patients were included in the study. At first progression, 62 (39.0%) were classified as undergoing oligoprogression. Multivariate analysis confirmed the presence of brain metastases was associated with an increased likelihood of oligoprogression (OR = 2.44, p = 0.04) with most (63.2%) of these patients experiencing progression intracranially. The presence of liver metastases was associated with a decreased likelihood of oligoprogression (OR = 0.17, p < 0.01). For patients with oligoprogression, those who received radiotherapy had a longer median progression-free survival-2 (PFS2) (17 versus 11.5 mo, HR = 0.51, p = 0.02) and a longer median OS (23 versus 13 mo, HR = 0.40, p < 0.001) compared with those who did not receive radiotherapy. No difference in PFS2 or OS outcomes was observed between patients who received radiotherapy versus those who did not for systemic progression. Conclusions: In patients with oligoprogressive metastatic NSCLC after treatment with first-line ICIs, radiotherapy significantly improves OS and PFS2 outcomes. Patients with baseline brain metastases are more likely to experience oligoprogression. Further prospective studies in directed, less heterogeneous populations of patients with metastatic NSCLC will be fundamental to optimize management.

Synchronous Oligometastasis and Oligoprogression as a Prognostic Marker in Patients With Extensive-Stage SCLC Treated With a Combination of Immune-Checkpoint Inhibitor and Chemotherapy (HOT2301).

Introduction: Oligometastasis and oligoprogression (OP) has not been adequately defined in extensive-stage SCLC (ES-SCLC) and may be a good indication for adding local treatment. Therefore, this multicenter study aimed to investigate the prognostic impact of oligometastasis and OP in ES-SCLC. Methods: We enrolled patients who received chemoimmunotherapy between September 2019 and June 2022. Patients were classified into oligometastasis and non-oligometastasis groups by determining the number of original tumor lesions and distant metastases (worsening or newly appearing lesions) at the time of initial diagnosis and disease progression after first-line treatment. Results: We retrospectively analyzed 265 consecutive patients with ES-SCLC. Synchronous oligometastasis (SOM) and OP was defined as less than or equal to five lesions in less than or equal to two organs, including lungs; 21.0% and 53.2% of patients had SOM and OP, respectively. Median progression-free survival was 5.8 months and 4.9 months in patients with and without SOM, respectively (hazard ratio [HR] = 0.72, 95% confidence interval [CI]: 0.51-1.02, p = 0.065). Median overall survival was 20.5 months and 15.0 months in patients with and without SOM (HR = 0.58, 95% CI: 0.37-0.95, p = 0.027) from the initiation of first-line treatment. The OP group revealed a better progression-free survival of 5.2 months (versus 3.2 mo, HR = 0.69, 95% CI: 0.50-0.96, p = 0.026) and overall survival of 15.1 months (versus 7.5 mo, HR = 0.44, 95% CI: 0.29-0.66, p = 0.027) from the initiation of second-line treatment compared with the non-OP group. The Lung Immune Prognostic Index score was significantly lower in the SOM and OP group. Conclusions: ES-SCLC in patients with SOM and OP may be more indolent than that of the nonoligometastasis group, therefore, new treatment strategies, including the addition of local treatment, should be explored. Clinical trial registration: This study was registered at UMIN-CTR (UMIN000053402).

A new proposal of simplified classification of non-small cell lung cancer oligometastases for easy applicability through systematic literature analysis and meta-analysis validation.

INTRODUCTION: Oligometastasis (OM) exhibits wide range of prognosis, which necessitates appropriate classification for optimal therapeutic decision-making. Complementing the ESTRO-EORTC classification which lacked prognostic differentiation and was rather complex, we propose a new and simpler classification based on systematic literature analysis and meta-analysis validation. METHOD: The databases were searched up to April 2024. Inclusion criteria were (1) ≥ 10 Non-small cell lung cancer OM patients, (2) local ablative treatment (LAT) versus control (systemic/supportive treatment), (3) reporting progression free survival (PFS) or overall survival (OS), respectively. A simpler classification was proposed through systematic reviews evaluating outcomes based on OM characteristics. According to this new classification, the LAT benefit and pooled 2-year OS and 1-year PFS percentiles were validated through meta-analysis. RESULTS: In overall meta-analysis, LAT was correlated with enhanced 1-year PFS (odds ratio (OR):3.487, p < 0.001) and 2-year OS (OR:2.984, p < 0.001), respectively. According to simplified classification, LAT benefit of 1-year PFS was differentiated with ORs of 5.631 (p < 0.001), 3.484 (p < 0.001), and 1.702 (p = 0.067) for Synchronous (Syn), OPS (Oligopersistence), and OPR (Oligoprogression/recurrence) subgroups, respectively. Inter-subgroup comparisons showed significant differences as well. For 2-year OS, ORs of LAT benefit were 3.366 (p < 0.001), 3.355 (p < 0.001), and 1.821 (p = 0.127) in Syn, OPS, and OPR subgroups, respectively; LAT benefit was significant in Syn and OPS, but not significant in OPR. In pooled percentile comparison, 1-year pooled PFS was significantly lower in the OPR group than others, both in the LAT and control arms. CONCLUSION: Based on a systematic literature analysis and meta-analysis validation, we developed a simpler three-step OM classification: Syn, OPS, and OPR. We would propose this new classification that is simpler and more applicable to clinical decisions than the currently available classification.

Outcomes of Post-Immunotherapy Durable Responders of Advanced Hepatocellular Carcinoma- with Emphasis on Locoregional Therapy for Oligoprogression.

Introduction: The progression patterns, dispositions, and outcomes of patients with advanced hepatocellular carcinoma (HCC) who achieved durable responses with immunotherapy remain poorly characterized. Methods: Patients with advanced HCC who received immune checkpoint inhibitor (ICI)-based immunotherapy and achieved durable responses were retrospectively included. A durable response was defined as partial response (PR) or stable disease (SD) per RECIST 1.1 for more than 8 months after initiation of immunotherapy. Oligoprogression and polyprogression were defined as progression at ≤3 and >3 lesions, respectively. Results: A total of 91 durable responders (63 PR and 28 SD) were identified. The majority had chronic viral hepatitis (n = 69, 75.8%). Forty-seven (51.6%) and 44 (48.4%) patients received the index immunotherapy as first-line and second- or beyond-line therapy, respectively. Fifty-four (59.3%) patients subsequently developed progression, with a predominant pattern of oligoprogression (66.7%). The median overall survival (OS) was 46.2 months (95% CI: 34.1-58.3). For patients with subsequent progression, employment of locoregional therapy (LRT) for progression was associated with prolonged OS (univariate analysis: hazard ratio [HR] 0.397, p = 0.009; multivariate analysis: HR 0.363, p = 0.050). Patients with oligoprogression who received LRT showed longer median OS than those who did not (48.4 vs. 20.5 months, p < 0.001). In contrast, the median OS of patients with polyprogression who received LRT was not different from those without LRT (27.7 vs. 25.5 months, p = 0.794). Conclusion: Approximately 60% of the post-immunotherapy durable responders of HCC subsequently develop progression. Proactive LRT may further rescue patients who develop subsequent oligoprogression. Prospective studies are mandatory to clarify the proper management of durable responders with subsequent progression.

Patterns of failure and the subsequent treatment after progression on first-line immunotherapy monotherapy in advanced non-small cell lung cancer: a retrospective study.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have become the recommended first-line treatment for advanced non-small cell lung cancer (NSCLC) without driver gene mutations. However, data on the failure patterns of first-line ICIs monotherapy is limited, and the optimal strategy for subsequent treatment remains controversial. METHODS: Advanced NSCLC patients receiving first-line ICIs monotherapy at Guangdong Lung Cancer Institute between December 2017 and October 2021 were identified. The progressive sites were recorded to analyze failure patterns. Post-progression survival (PPS) was compared between different treatment regimens. RESULTS: A total of 121 patients receiving first-line ICIs monotherapy were identified, with a median progression-free survival of 8.6 months. Sixty-five patients had available imaging at diagnosis as well as progressive disease, with 56.9% showing oligoprogression. For those with progression in existing lesions, the most common sites were the liver (77.8%) and lung parenchyma (62.5%), while progression with new lesions frequently occurred in the liver (32.0%). Fifty patients with recorded subsequent treatment were included in the analysis of subsequent treatment patterns. Patients treated with anti-angiogenesis therapy could get better PPS (HR: 0.275, P = 0.013). Isolated oligoprogression occurred most often in the lung parenchyma and intracranial lesions. More than half of these patients continued immunotherapy after local treatment, with a 2.5-year PPS rate of 51.4%. CONCLUSION: The liver was the most common site of progression on first-line ICIs monotherapy. Anti-angiogenesis-based therapy might be an optimal regimen at the time of progression. Patients with isolated oligoprogressive could still benefit from immunotherapy after local treatment.

Stereotactic ablative radiotherapy for oligoprogressive solid tumours: A systematic review and meta-analysis.

INTRODUCTION: The aim of this systematic review and meta-analysis was to review evidence and pool outcomes to assess the effectiveness of stereotactic ablative radiotherapy (SABR) in patients treated for oligoprogressive metastases. METHODS AND MATERIALS: A search was conducted January 2010 to January 2023 in five bibliographic databases for studies of patients with oligoprogressive disease treated with SABR to all lesions. Clinical outcomes included PFS (progression-free survival), OS (overall survival) and CST (change in systemic therapy). Descriptive statistics were used to summarize the data. Binary random effects model was used for pooled analyses. RESULTS: 12,366 titles/abstracts screened, of which 25 met eligibility criteria and were included the review. All studies were published after 2017 with approximately 80% of the publications in 2021 and 2022. The primary tumour was prostate (n=8, 32%), kidney (n=6, 24%), colorectal (n=4, 16%) followed by breast (n=3, 12%), lung (n=2, 8%) and mixed (n=3, 12%). At 1 year, the pooled PFS was 44% (95% confidence interval [CI]: 34-53%, I2=91%); 53% (95% CI: 45-60%, I2=46%) in prostate, 49% (95% CI: 33-65%, I2=88%) in kidney, 62% (95% CI: 11-113%, I2=96%) in lung, 13% (95% CI: 3-24%, I2=39%) in breast and 30% (95% CI: 19-41%, I2=59%) in mixed. DISCUSSION: There has been a surge in publications describing the use of SABR in oligoprogressive tumours. Published studies are mostly retrospective reported in prostate and kidney cancers, with limited evidence in other sites. Universal guidelines are recommended to ensure consistency in reporting and comparability of future studies.

Complete response in a lung adenocarcinoma with pleural metastases initially treated with gefitinib and switched to osimertinib after cerebral oligo-progression with unknown T790M mutation: a case report and review of literature.

BACKGROUND: First- and second-generation anti-epithelial growth factor receptor tyrosine kinase inhibitors have shown great efficacy in the treatment of advanced adenocarcinoma with epithelial growth factor receptor mutations, but this efficacy is limited by certain resistance mechanisms, in particular the T790M mutation, which must be screened before second-line treatment with osimertinib is indicated. The search for this mutation is sometimes difficult, especially in cases of intracranial relapse, through this case report we attempt to discuss the possibility of initiating treatment with osimertinib despite an unknown T790M mutation in such situation. CASE REPORT: We present the case of a 70-year-old Moroccan male patient diagnosed with non-small cell lung carcinoma initially metastatic to the pleura with an epithelial growth factor receptor mutation who received gefitinib in first line with a complete response, he subsequently presented with cerebral oligo-progression with extra cranial stability. The patient was started on osimertinib with unknown T790M status, as it was impossible to perform a cerebral biopsy, the evolution was characterized by a partial response followed by stereotactic radiotherapy then a complete response for 2 years. CONCLUSION: We can discuss osimertinib as an option for patients with stage IV non-small cell lung cancer with brain oligo-progression on prior tyrosine kinase inhibitors and unknown T790M status, further studies are needed in this area.

Outcomes Analysis of Patients Receiving Local Ablative Therapy for Oligoprogressive Metastatic NSCLC Under First-Line Immunotherapy.

CONTEXT: Nonsmall Cell Lung Cancer (NSCLC) treatment relies on first-line immunotherapy as single agent or combined with chemotherapy. Oligoprogression may be observed in this setting. MATERIAL AND METHOD: We performed a European multicentric retrospective study on patients treated with first-line immunotherapy, who presented with oligoprogressive disease, treated with a local ablative treatment. RESULTS: A total of 61 patients were retrospectively included between 2018 and 2022. Twenty-four patients (39%) received immunotherapy as single agent, and 37 (61%) chemo-immunotherapy. First oligoprogression occurred more frequently in pre-existing metastatic sites (47% of patients). Median PFS1 (defined as time to first oligoprogression) was 11.5 months [IC95%: 10.0-12.3]. We observed that 37 patients (61%) progressed after first oligoprogression, and 20 (54%) from them presented second oligoprogression. Median OS for the whole cohort was 72.0 months [IC95%: 19.3-124.8], with positive correlation between OS and PFS1 (R=0.65, P < .0001). After loco-ablative treatment with radiotherapy, disease control rate was 89% with ablative radiotherapy: 88% with conventional radiotherapy, and 89% with stereotactic radiotherapy. CONCLUSION: Patients with oligoprogression under/after immunotherapy have better prognosis with a high risk of subsequent oligoprogression.

Outcomes of Radiotherapy in Oligoprogressive Breast Cancer.

INTRODUCTION: Radiotherapy (RT) shows potential for improving local control in cases of oligoprogressive metastatic breast cancer (mBC). This retrospective analysis aims to evaluate the advantages of RT in such a clinical scenario. METHODS: We conducted a retrospective analysis including patients with mBC who received radiation therapy (RT) for up to three sites of oligoprogression while continuing systemic therapy. The study took place between January 2014 and December 2021. Our endpoints were progression-free survival after radiotherapy (PFS-AR), the rate of discontinuation of systemic therapy (RDT) at three months post-RT, and overall survival (OS). We used Cox regression analysis to perform multivariate analysis for PFS-AR. RESULTS: Fifty-nine patients met the inclusion criteria. The PFS-AR was 13 months (95% CI 8.5-18.8 months). At three months, the RDT was 3% (two patients). A significant difference in median PFS-AR was observed between patients in the first + second-line group and those in the subsequent line group (p = 0.03). In the multivariate analysis conducted for PFS-AR, the biologically effective dose (BED) with α/ß = 4 > 100 Gy emerged as the sole significant variable (p = 0.0017). The median overall survival (OS) was 24.4 months (95% CI 17-24.4 months). CONCLUSIONS: This study is the first report on the outcomes of radiotherapy in a cohort of over 50 patients with oligoprogressive metastatic breast cancer (mBC). Our findings emphasize the significant relationship between PFS-AR, the number of ongoing lines of systemic therapy, and the BED of radiotherapy.

Management of oligometastatic and oligoprogressive epidermal growth factor receptor mutated non-small cell lung cancer patients: state of the art of a combined approach.

Recently, the development of targeted therapy approaches such as those based on tyrosine kinase inhibitor (TKI) greatly improved the clinical outcomes of patients affected by oncogene addicted advanced non-small cell lung cancer (NSCLC). Similarly, the improvement of radiation therapy techniques has permitted to deliver high radiation doses to a limited number of metastatic target lesions (oligopersistent or oligoprogressive), with limited high-dose normal tissue exposure that leads to low severe toxicity rates. The aim of this narrative review was to provide an overview of the currently established definition of oligometastatic and oligoprogressive disease, to define first line and subsequent lines targeted therapies and the role of consolidative non-invasive local ablative treatments (LATs) in these settings. The potential benefit of local treatment (LT) such as radiotherapy (RT) or surgery might be represented by an overall reduction of switching to subsequent systemic treatments lowering the risk of further systemic dissemination. Further randomized clinical trials will clarify the role of LT and their correct timing in relation to systemic targeted therapies.

Stereotactic Body Radiotherapy for Oligoprogression in Castration-Resistant Prostate Cancer: Early Toxicity Analysis of the TRAP Trial.

AIMS: To assess toxicity and patient quality of life after stereotactic body radiotherapy (SBRT) to oligoprogressive disease (OPD) in patients with metastatic castrate-resistant prostate cancer (CRPC) on androgen receptor targeted agents (ARTA). MATERIAL AND METHODS: This phase II trial enrolled patients with metastatic CRPC with ≤ 2 oligoprogressive lesions in bone, lymph node, lung, or prostate. All patients were receiving systemic treatment with abiraterone or enzalutamide at the time of oligoprogression. All patients received SBRT to the OPD site(s) and continued the current ARTA. Patients received 30 Gy in 5 fractions (alternate days) to the OPD site. The primary endpoint of the trial is to assess if SBRT to OPD sites results in progression free survival of >6 months. The primary endpoint for this toxicity analysis is the rate of grade 3 or higher adverse events at any timepoint up to 6 months after SBRT. Secondary endpoints included comparing pre- and post-SBRT patient-related outcomes reported using visual analogue scale scores and EQ-5D health questionnaire. RESULTS: Forty enrolled patients had at least 6 months of follow-up at the time of analysis. Grade 3 or higher toxicity from any cause recorded using common terminology criteria for adverse events and radiation therapy oncology group was found in 8/40 (20%) of patients, but only 1/40 (2.5%) was deemed possibly related to SBRT. There was no significant difference in mean EQ5D visual analogue scale score from baseline to each timepoint after SBRT (p = 0.449). CONCLUSION: In this prospective phase II clinical trial for OPD whilst on ARTA in the CRPC setting, we report low grade ≥ 3 toxicity after SBRT. There is no discernible change in patient-reported quality of life due to SBRT treatment. The final results of progression-free survival and toxicity of SBRT treatment will be reported once further follow-up is complete.

The analysis of the efficacy and safety of stereotactic body radiotherapy with sequential immune checkpoint inhibitors in the management of oligoprogressive advanced non-small cell lung cancer.

Background: No standardized treatment strategy exists for managing oligoprogression during maintenance therapy in driver-negative advanced non-small cell lung cancer (NSCLC). Similarly, a uniform response to oligoprogression during maintenance therapy using immune checkpoint inhibitors (ICIs) has not been established. Consequently, our investigation focused on assessing the efficacy and safety of employing stereotactic total body radiotherapy in conjunction with ICIs to address oligoprogression in advanced NSCLC. Methods: We conducted a retrospective analysis of patients diagnosed with driver-negative advanced NSCLC who received stereotactic body radiotherapy (SBRT) in combination with ICIs to manage oligoprogressive lesions within the period from October 2018 to October 2023 at our institution. Oligoprogression, defined as progression occurring in three or fewer disease sites, was the focus of our investigation. Our assessment encompassed various parameters including the local control rate (LCR), progression-free survival post-oligoprogression (PFS-P), overall survival post-oligoprogression (OS-P), progression-free survival (PFS), overall survival (OS), and the safety profile associated with SBRT followed by sequential ICIs after oligoprogression. Results: A total of 15 patients were enrolled in this study, all at stage IV, with 12 (80%) receiving a diagnosis of adenocarcinoma. Before oligoprogression, 11 (73.3%) patients had undergone immunotherapy. Following the treatment of oligoprogressed lung cancer with SBRT sequential ICIs, the median PFS-P and OS-P were 8 months (95% CI: 2.7-13.3) and 12 months (95% CI: 7.3-16.7), respectively. Additionally, the median PFS and OS were 26 months (95% CI: 8.0-44.0) and 30 months (not reached), respectively. The median local control (LC) of 15 oligoprogressed lesions was 13 months (95% CI: 5.3-20.2), with a 1-year LCR of 77.9%. Notably, patients with a performance status (PS) score of less than 2 demonstrated a more favorable survival benefit. Conclusions: Stereotactic systemic radiation therapy, combined with sequential ICIs, enhances both LC and survival in advanced NSCLC characterized by oligoprogression and negative driver gene mutations. This approach also exhibits the potential to postpone the transition between systemic chemotherapy regimens. Manageable adverse reactions were observed, with the absence of grade 4 reactions.

Clinical Outcomes of Online Adaptive Magnetic Resonance-Guided Stereotactic Body Radiotherapy of Adrenal Metastases from a Single Institution.

(1) Background: Recent publications foster stereotactic body radiotherapy (SBRT) in patients with adrenal oligometastases or oligoprogression. However, local control (LC) after non-adaptive SBRT shows the potential for improvement. Online adaptive MR-guided SBRT (MRgSBRT) improves tumor coverage and organ-at-risk (OAR) sparing. Long-term results of adaptive MRgSBRT are still sparse. (2) Methods: Adaptive MRgSBRT was performed on a 0.35 T MR-Linac. LC, overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and toxicity were assessed. (3) Results: 35 patients with 40 adrenal metastases were analyzed. The median gross tumor volume was 30.6 cc. The most common regimen was 10 fractions at 5 Gy. The median biologically effective dose (BED10) was 75.0 Gy. Plan adaptation was performed in 98% of all fractions. The median follow-up was 7.9 months. One local failure occurred after 16.6 months, resulting in estimated LC rates of 100% at one year and 90% at two years. ORR was 67.5%. The median OS was 22.4 months, and the median PFS was 5.1 months. No toxicity > CTCAE grade 2 occurred. (4) Conclusions: LC and ORR after adrenal adaptive MRgSBRT were excellent, even in a cohort with comparably large metastases. A BED10 of 75 Gy seems sufficient for improved LC in comparison to non-adaptive SBRT.

Progression-directed Therapy in Oligoprogressive Castration-resistant Prostate Cancer: Final Results from the Prospective, Single-arm, Phase 2 MEDCARE Trial.

BACKGROUND AND OBJECTIVE: Next-line systemic treatment (NEST) is the standard of care for patients presenting with progressive metastatic castration-resistant prostate cancer (mCRPC). Progression-directed therapy (PDT), defined as a lesion-directed approach in patients with a limited number of progressive and/or new lesions, could postpone the need for NEST in these patients with so-called oligoprogressive mCRPC. Our aim was to investigate the feasibility of postponing NEST initiation in oligoprogressive mCRPC by using PDT. METHODS: MEDCARE was a prospective, single-arm, nonrandomized phase 2 trial. Eligible patients had oligoprogressive mCRPC and were treated with PDT while their ongoing systemic therapy was continued. The primary endpoint was NEST-free survival (NEST-FS). Secondary endpoints were prostate-specific antigen response, clinical progression-free survival (cPFS), prostate cancer-specific survival (PCSS), overall survival (OS), and PDT-induced toxicity. KEY FINDINGS AND LIMITATIONS: Twenty patients underwent PDT for 38 oligoprogressive lesions. At median follow-up of 28 mo, median NEST-FS was 17 mo and the 2-yr NEST-FS rate was 35%. Median PCSS and median OS were not reached. The PCSS and OS rates at 2 yr were 80% and 70%, respectively. The 2-yr local control rate was 95%. No patient experienced early or late grade ≥3 toxicity. NEST-FS was longer for patients who received PDT to all lesions visible on 18F-PSMA positron emission tomography/computed tomography (30 vs 13 mo; p = 0.002). CONCLUSIONS AND CLINICAL IMPLICATIONS: This single-center, single-arm, phase 2 trial demonstrated that PDT in oligoprogressive mCRPC resulted in median NEST-FS of 17 mo without any early or late grade ≥3 toxicity. PATIENT SUMMARY: For patients with metastatic prostate cancer no longer responding to hormone therapy, we investigated radiotherapy targeted at progressive cancer lesions while continuing their ongoing systemic treatment. The results show that this targeted therapy had very low toxicity and delayed the need to start a new line of systemic treatment by 17 months.

Treatment Outcomes of Stereotactic Ablative Body Radiotherapy on Extra-cranial Oligometastatic and Oligoprogressive Breast Cancer: Mature Results from a Single Institution Experience.

AIMS: Evidence shows stereotactic ablative body radiotherapy (SABR) is used as a non-invasive ablative therapy in the treatment of multisite oligometastatic (OM) and oligoprogressive (OP) diseases originating from metastatic breast cancer. This study aims to report the treatment outcomes and to investigate what factors that are prognostic in terms of local control, progression-free survival (PFS) and overall survival (OS) in patients receiving SABR for extracranial OM and OP diseases originating from metastatic breast cancer. MATERIALS AND METHODS: A retrospective review on treatment records of patients with OM and OP from metastatic breast cancer who underwent SABR at a single was carried out. SABR was performed with daily image-guided radiotherapy (IGRT) using a dedicated robotic SABR machine. Local control, PFS and OS were calculated using Kaplan-Meier statistics and the post-treatment toxicity data was scored following the CTCAE v4.0 protocol. Univariate and multivariate Cox regression tests were used in the subgroup analysis of prognostic factors on PFS and OS including patients' age, types of follow-up imaging (staging CT only vs whole-body MR/PET), metastases status (OM vs OP), primary breast cancer tumour grade, hormone receptors (ER/PR/HER2) status, change of systemic treatments at SABR, number of metastases, SABR treatment sites and doses. RESULTS: 56 metastatic breast cancer patients (38 patients with OM and 18 patients with OP) were involved in this retrospective review. The median follow-up was 35.6 months (range 4.0-132.9 months). The estimated local control at 1 , 2 and 5 years were 90.9%, 88.7% and 88.7%, respectively. The estimated median PFS was 19.2 months (95%CI 10.3-28.1 months); the PFS at 1, 2 and 5 years were 63.3%, 44.4% and 33.2%. The estimated OS at 1, 2 and 5 years were 98.0%, 91.9% and 74.3%, respectively with the estimated median OS of 105.1 months (95%CI 51.5-158.7 months). The vast majority of patients tolerated the treatment well with the commonest acute side effects as grade 1 fatigue. There were no statistically significant factors found in OS regression analysis. The types of follow-up imaging, metastases status, oestrogen receptor status, and number of metastases for SABR were statistically significant factors (p < 0.05) in the multivariate Cox regression analysis on PFS. CONCLUSION: There are limited studies published on the efficacy and post-treatment toxicities of metastatic breast cancer OM and OP SABR with adequate length of follow-up. This study confirmed that SABR was a safe, non-invasive treatment option for patients with extracranial OM and OP diseases originated from primary breast cancer in terms of the acceptable post-treatment toxicities.

Novel Blood Biomarkers for Response Prediction and Monitoring of Stereotactic Ablative Radiotherapy and Immunotherapy in Metastatic Oligoprogressive Lung Cancer.

Up to 80% of patients under immune checkpoint inhibitors (ICI) face resistance. In this context, stereotactic ablative radiotherapy (SABR) can induce an immune or abscopal response. However, its molecular determinants remain unknown. We present early results of a translational study assessing biomarkers of response to combined ICI and SABR (I-SABR) in liquid biopsy from oligoprogressive patients in a prospective observational multicenter study. Cohort A includes metastatic patients in oligoprogression to ICI maintaining the same ICI due to clinical benefit and who receive concomitant SABR. B is a comparative group of oligometastatic patients receiving only SABR. Blood samples are extracted at baseline (T1), after the first (T2) and last (T3) fraction, two months post-SABR (T4) and at further progression (TP). Response is evaluated by iRECIST and defined by the objective response rate (ORR)-complete and partial responses. We assess peripheral blood mononuclear cells (PBMCs), circulating cell-free DNA (cfDNA) and small RNA from extracellular vesicles. Twenty-seven patients could be analyzed (cohort A: n = 19; B: n = 8). Most were males with non-small cell lung cancer and one progressing lesion. With a median follow-up of 6 months, the last ORR was 63% (26% complete and 37% partial response). A decrease in cfDNA from T2 to T3 correlated with a good response. At T2, CD8+PD1+ and CD8+PDL1+ cells were increased in non-responders and responders, respectively. At T2, 27 microRNAs were differentially expressed. These are potential biomarkers of response to I-SABR in oligoprogressive disease.

Stereotactic Body Radiotherapy for Extracranial Oligometastatic Disease from Head and Neck Primary Cancers: A Systematic Review and Meta-Analysis.

INTRODUCTION: Stereotactic body radiotherapy (SBRT) is increasingly used to treat disease in the oligometastatic (OM) setting due to mounting evidence demonstrating its efficacy and safety. Given the low population representation in prospective studies, we performed a systematic review and meta-analysis of outcomes of HNC patients with extracranial OM disease treated with SBRT. METHODS: A systematic review was conducted with Cochrane, Medline, and Embase databases queried from inception to August 2022 for studies with extracranial OM HNC treated with stereotactic radiotherapy. Polymetastatic patients (>five lesions), mixed-primary cohorts failing to report HNC separately, lack of treatment to all lesions, nonquantitative endpoints, and other definitive treatments (surgery, conventional radiotherapy, and radioablation) were excluded. The meta-analysis examined the pooled effects of 12- and 24-month local control (LC) per lesion, progression-free survival (PFS), and overall survival (OS). Weighted random-effects were assessed using the DerSimonian and Laird method, with heterogeneity evaluated using the I2 statistic and Cochran Qtest. Forest plots were generated for each endpoint. RESULTS: Fifteen studies met the inclusion criteria (639 patients, 831 lesions), with twelve eligible for quantitative synthesis with common endpoints and sufficient reporting. Fourteen studies were retrospective, with a single prospective trial. Studies were small, with a median of 32 patients (range: 6-81) and 63 lesions (range: 6-126). The OM definition varied, with a maximum of two to five metastases, mixed synchronous and metachronous lesions, and a few studies including oligoprogressive lesions. The most common site of metastasis was the lung. Radiation was delivered in 1-10 fractions (20-70 Gy). The one-year LC (LC1), reported in 12 studies, was 86.9% (95% confidence interval [CI]: 79.3-91.9%). LC2 was 77.9% (95% CI: 66.4-86.3%), with heterogeneity across studies. PFS was reported in five studies, with a PFS1 of 43.0% (95% CI: 35.0-51.4%) and PFS2 of 23.9% (95% CI: 17.8-31.2%), with homogeneity across studies. OS was analyzed in nine studies, demonstrating an OS1 of 80.1% (95% CI: 74.2-85.0%) and OS2 of 60.7% (95% CI: 51.3-69.4%). Treatment was well tolerated with no reported grade 4 or 5 toxicities. Grade 3 toxicity rates were uniformly below 5% when reported. CONCLUSIONS: SBRT offers excellent LC and promising OS, with acceptable toxicities in OM HNC. Durable PFS remains rare, highlighting the need for effective local or systemic therapies in this population. Further investigations on concurrent and adjuvant therapies are warranted.

Uncovering the armpit of SBRT: An institutional experience with stereotactic radiation of axillary metastases.

Purpose/objectives: The growing use of stereotactic body radiotherapy (SBRT) in metastatic cancer has led to its use in varying anatomic locations. The objective of this study was to review our institutional SBRT experience for axillary metastases (AM), focusing on outcomes and process. Materials/methods: Patients treated with SBRT to AM from 2014 to 2022 were reviewed. Cumulative incidence functions were used to estimate the incidence of local failure (LF), with death as competing risk. Kaplan-Meier method was used to estimate progression-free (PFS) and overall survival (OS). Univariate regression analysis examined predictors of LF. Results: We analyzed 37 patients with 39 AM who received SBRT. Patients were predominantly female (60 %) and elderly (median age: 72). Median follow-up was 14.6 months. Common primary cancers included breast (43 %), skin (19 %), and lung (14 %). Treatment indication included oligoprogression (46 %), oligometastases (35 %) and symptomatic progression (19 %). A minority had prior overlapping radiation (18 %) or surgery (11 %). Most had prior systemic therapy (70 %).Significant heterogeneity in planning technique was identified; a minority of patient received 4-D CT scans (46 %), MR-simulation (21 %), or contrast (10 %). Median dose was 40 Gy (interquartile range (IQR): 35-40) in 5 fractions, (BED10 = 72 Gy). Seventeen cases (44 %) utilized a low-dose elective volume to cover remaining axilla.At first assessment, 87 % had partial or complete response, with a single progression. Of symptomatic patients (n = 14), 57 % had complete resolution and 21 % had improvement. One and 2-year LF rate were 16 % and 20 %, respectively. Univariable analysis showed increasing BED reduced risk of LF. Median OS was 21.0 months (95 % [Confidence Interval (CI)] 17.3-not reached) and median PFS was 7.0 months (95 % [CI] 4.3-11.3). Two grade 3 events were identified, and no grade 4/5. Conclusion: Using SBRT for AM demonstrated low rates of toxicity and LF, and respectable symptom improvement. Variation in treatment delivery has prompted development of an institutional protocol to standardize technique and increase efficiency. Limited followup may limit detection of local failure and late toxicity.

Patterns of Failure in Metastatic NSCLC Treated With First Line Pembrolizumab and Use of Local Therapy in Patients With Oligoprogression.

INTRODUCTION: The patterns of failure (POF) for metastatic non-small-cell lung cancer (mNSCLC) treated with immunotherapy are not well established. METHODS: We conducted a retrospective cohort study of mNSCLC that received first-line pembrolizumab with or without chemotherapy at a single academic center from 2015 to 2021. We defined POF with 2 classifications: 1) local, regional, or distant failure, or 2) failure in existing lesions, new lesions, or a combination. Oligoprogression was defined as disease progression (PD) in ≤3 sites of failure. Overall survival (OS) was measured via Kaplan-Meier and modelled with Cox regression. RESULTS: Of 298 patients identified, 198 had PD. Using POF classification 1, most failures were distant (43.9%) or a combination of locoregional and distant (34.4%). For POF classification 2, failures occurred in a combination of new and existing lesions (45.0%), existing lesions alone (33.3%), or in new lesions only (21.7%). Oligoprogression occurred in 39.9% (n = 79) cases. Median OS was higher in the following: PD in existing lesions vs. new or new + existing lesions (28.7 vs. 20.2 vs. 13.9 months, P < .001) and oligoprogression vs. polyprogression (35.1 vs. 12.2 months, P < .001). In oligoprogression, median OS was better for those who received radiation to all sites of PD (62.2 months) than for those who changed systemic therapy (22.9 months, P = .007). On multivariable analysis, radiation for oligoprogression (HR 0.35, 95% CI: 0.20-0.62, P < .001) was associated with improved OS. CONCLUSIONS: In mNSCLC treated with pembrolizumab, oligoprogression is relatively common. Randomized data are needed to define the benefits of radiation in oligoprogressive mNSCLC.