Towards a molecular basis of oligometastatic disease: potential role of micro-RNAs

Tumor-infiltrating lymphocyte as a prognostic biomarker in stage IV colorectal cancer should take into account the metastatic status and operation modality

BACKGROUND

Although tumor-infiltrating lymphocytes (TILs) have been understood for years as a favorable prognostic factor for colorectal cancers (CRCs) after complete surgical resection, its prognostic role in metastatic CRC (mCRC) remains poorly defined, and it is largely unknown how this prognostic benefit relates to the metastatic status and operation modality.

MATERIALS AND METHODS

After reviewing 2215 consecutive cases of surgically resected CRC, 332 patients newly diagnosed with stage IV CRC and treated at the Sun Yat-Sen University Cancer Center between 2009 and 2014 were included. H&E-stained (HES) slides from surgical specimens were evaluated for the extent of TILs. The primary end point was overall survival (OS). Cox proportional hazards regression was conducted to determine the prognostic significance of TILs. All statistical tests were 2-sided.

RESULTS

HES slides from primary tumor samples were evaluable for 302 of the 332 included cases. Among the 302 patients, 105 patients (34.8%) were classified as high TIL, the remaining 197 (65.2%) were defined as low TIL. In the univariate analysis, TILs were significantly associated with better OS (P=0.015). Multivariable analysis confirmed that high TIL strongly predicted better survival (hazard ratio =0.62, 95% CI: 0.44-0.89, P=0.008), independent of other patients' clinicopathological characteristics. Stratified analysis revealed a prognostic benefit of high TIL for patients in the subgroup with non-oligometastatic disease (P=0.002), ≥2 metastatic organs (P=0.006), and non-metastasectomy (P=0.005). By contrast, oligometastatic disease, 1 metastatic organ, or metastasectomy fully abrogated the prognostic effect of TIL.

CONCLUSION

Our findings indicate that the level of TILs can be used to predict the outcome for patients with mCRC; however, the operation modality and the metastatic status of patients should also be taken into account.

Stereotactic Body Radiotherapy for Oligometastasis: Opportunities for Biology to Guide Clinical Management

Oligometastasis refers to a state of limited metastatic disease burden, in which surgical or ablative treatment to all known visible metastases holds promise to extend survival or even effect cure. Stereotactic body radiotherapy is a form of radiation treatment capable of delivering a high biologically effective dose of radiation in a highly conformal manner, with a favorable toxicity profile. Enthusiasm for oligometastasis ablation, however, should be counterbalanced against the limited supporting evidence. It remains unknown to what extent (if any) ablation influences survival or quality of life. Rising clinical equipoise necessitates the completion of randomized controlled trials to assess this, several of which are underway. However, a lack of clear identification criteria or biomarkers to define the oligometastatic state hampers optimal patient selection.This narrative review explores the evolutionary origins of oligometastasis, the steps of the metastatic process at which oligometastases may arise, and the biomolecular mediators of this state. It discusses clinical outcomes with treatment of oligometastases, ongoing trials, and areas of basic and translational research that may lead to novel biomarkers. These efforts should provide a clearer, biomolecular definition of oligometastatic disease and aid in the accurate selection of patients for ablative therapies.

In Vivo Delivery and Therapeutic Effects of a MicroRNA on Colorectal Liver Metastases

Multiple therapeutic agents are typically used in concert to effectively control metastatic tumors. Recently, we described microRNAs that are associated with the oligometastatic state, in which a limited number of metastatic tumors progress to more favorable outcomes. Here, we report the effective delivery of an oligometastatic microRNA (miR-655-3p) to colorectal liver metastases using nanoscale coordination polymers (NCPs). The NCPs demonstrated a targeted and prolonged distribution of microRNAs to metastatic liver tumors. Tumor-targeted microRNA miR-655-3p suppressed tumor growth when co-delivered with oxaliplatin, suggesting additive or synergistic interactions between microRNAs and platinum drugs. This is the first known example of systemically administered nanoparticles delivering an oligometastatic microRNA to advanced metastatic liver tumors and demonstrating tumor-suppressive effects. Our results suggest a potential therapeutic strategy for metastatic liver disease by the co-delivery of microRNAs and conventional cytotoxic agents using tumor-specific NCPs.

Percutaneous CT-guided radiofrequency ablation for patients with extrahepatic oligometastases of hepatocellular carcinoma: long-term results

BACKGROUND

The aim of this study was to evaluate the therapeutic outcome of percutaneous computed tomography (CT)-guided radiofrequency ablation (RFA) for extrahepatic oligometastases of hepatocellular carcinoma (HCC).

METHODS

Institutional review board approval was obtained for this retrospective study, and all patients provided written informed consent. Between April 2004 and December 2015, 116 oligometastases (diameter, 5-50 mm; 20.3 ± 10.4) in 79 consecutive HCC patients (73 men and 6 women; average age, 50.3 years ±13.0) were treated with RFA. We focussed on patients with 1-3 extrahepatic metastases (EHM) confined to 1-2 organs (including the lung, adrenal gland, bone, lymph node and pleura/peritoneum) who were treated naïve with curative intent. Survival, technical success and safety were evaluated. The log-rank test and Cox proportional hazards regression models were used to analyse the survival data.

RESULTS

No immediate technical failure occurred, and at 1 month, the technique effectiveness rate was determined to be 95.8%. After a median follow-up time of 28.0 months (range, 6-108 months), the 1-, 2- and 3-year overall survival (OS) rates were 91, 70 and 48%, respectively, with a median survival time of 33.5 months. Time to unoligometastatic progression (TTUP) of less than 6 months (p < 0.001) and a Child-Pugh score of more than 5 (p = 0.001) were significant indicators of shorter OS. The 1-, 2- and 3-year disease free survival (DFS) rates were 34, 21 and 8%, respectively, with a median DFS time of 6.8 months. DFS was better for those with lung metastases (p = 0.006). Major complication occurred in nine (9.5%, 9/95) RFA sessions without treatment-related mortality.

CONCLUSIONS

CT-guided RFA for oligometastatic HCC may provide favourable efficacy and technical success with a minimally invasive approach.

Unexpected long survival of brain oligometastatic non-small cell lung cancer (NSCLC) treated with multimodal treatment: a single-center experience and review of the literature

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Fifty percent of the cases are metastatic at diagnosis and about 20% develop brain metastasis. The brain involvement represents a negative prognostic factor. However, some patients could benefit from locoregional treatments of metastatic foci and experience an unexpected long survival or healing. In the previous years some classifications were proposed to identify patients' prognostic category, according to stage of the primary tumor, the timing of metastases occurrence (synchronous or metachronous) and the number of metastatic sites. Several data show a benefit in patients receiving resection of both the primary tumor and brain metastases. Whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) are the selected options in most cases. Overall, literature data showed highly variable outcome, with an overall survival (OS) ranging from 5.9 to 68 months. No data from randomized and homogeneous trials are currently available. Therefore, a growing interest in this field is observed. Different trials investigating the effectiveness of local treatments and studies analyzing biological mechanisms are ongoing. In this report we analyze literature data and we explore the current field of study. Furthermore, we show a single institutional experience of multimodal management of stage IV NSCLC with brain metastases, experiencing an unexpected long survival. We conclude that a better knowledge of this subpopulation of patients and new studies in this field can lead to distinguish the patients who can benefit from local treatment from those with poor prognosis.

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OLIGOMETASTASIS AND OLIGOPROGRESSION

Oligometastic progression (or solitary metastases) can justify ablative treatment for metastatic treatment. When such a strategy is discussed, it is important to notice that definition of oligometastases is not consensual both in terms of clinical presentation than on the biological basis. Does a specific biological background truly exist and are there markers that could predict for additional occult disease and its oligo or polymetastatic profile in individuals with demonstrated oligometastasis. This article provides a summary of the state of the art in this field and highlights some current areas of controversies.

Surgical cytoreduction of the primary tumor reduces metastatic progression in a mouse model of prostate cancer

Metastatic prostate cancer (mPCa) is one of the most prevalent cancers in men worldwide. The main cause of death in these patients is androgen-resistant metastatic disease. Surgery of the primary tumor has been avoided in these patients as there is no strong evidence that supports a beneficial effect. From the biological point of view, it appears rational to hypothesize that the primary tumor may contribute to the establishment and growth of metastases. Considering this, we propose that cytoreductive surgery (CS) in advanced metastatic stage slows the progression of metastatic disease. To test this, we used a mouse model of resectable orthotopic prostate cancer (PCa) and performed CS. After surgery, metastases were smaller and less numerous in the treated mice; an effect that was observable until the end of the experiment. These results suggest that CS alone delays the progression of metastatic disease and that although this effect may be temporary, it may translate to prolonged survival, especially when used with adjuvant therapy.

14q32-encoded microRNAs mediate an oligometastatic phenotype

Oligometastasis is a clinically distinct subset of metastasis characterized by a limited number of metastases potentially curable with localized therapies. We analyzed pathways targeted by microRNAs over-expressed in clinical oligometastasis samples and identified suppression of cellular adhesion, invasion, and motility pathways in association with the oligometastatic phenotype. We identified miR-127-5p, miR-544a, and miR-655-3p encoded in the 14q32 microRNA cluster as co-regulators of multiple metastatic pathways through repression of shared target genes. These microRNAs suppressed cellular adhesion and invasion and inhibited metastasis development in an animal model of breast cancer lung colonization. Target genes, including TGFBR2 and ROCK2, were key mediators of these effects. Understanding the role of microRNAs expressed in oligometastases may lead to improved identification of and interventions for patients with curable metastatic disease, as well as an improved understanding of the molecular basis of this unique clinical entity.

The evolving role of radiotherapy in treatment of oligometastatic NSCLC

Non-small cell lung cancer (NSCLC) patients with metastases limited in site and number, termed oligometastases, may represent a unique subpopulation of advanced NSCLC with improved prognosis. The optimal management of these patients remains unclear with the treatment approach currently undergoing a paradigm shift. The potential benefit of aggressive metastasis directed local treatment with surgery and/or radiotherapy (RT) in combination with systemic therapy is bolstered predominantly by retrospective analyses but also by a growing number of non-randomized prospective studies regarding the use of ablative RT techniques including stereotactic body radiotherapy (SBRT), alternatively termed stereotactic ablative radiotherapy (SABR), directed at the primary tumor (if present) and all metastatic sites. Long-term survival is possible in a subset of patients treated aggressively in this manner. The challenge for the clinical oncology community moving forward is appropriately selecting patients for this treatment approach based on clinical, imaging, and molecular features and increasing enrollment of patients to prospective clinical trials to more definitively determine the added benefit and appropriate timing of aggressive metastasis directed therapy in the oligometastatic setting.

Oligometastases in prostate cancer: restaging stage IV cancers and new radiotherapy options

There are various subgroups of patients with metastatic prostate cancer: polymetastatic, oligometastatic, or oligo-recurrent cancers whose progression follows different courses and for whom there are different treatment options. Knowledge of tumor dissemination pathways and different genetic and epigenetic tumor profiles, as well as their evolution during disease progression, along with new diagnostic and therapeutic advances has allowed us to address these situations with local ablative treatments such as stereotactic body radiation therapy or stereotactic radiosurgery. These treatments provide high rates of local control with low toxicity in metastatic spread for primary cancers including those of pulmonary, digestive, and renal origin, while these types of treatments are still emerging for cancers of prostatic origin. There are several retrospective studies showing the effectiveness of such treatments in prostate cancer metastases, which has led to the emergence of prospective studies on the issue and even some phase II studies intended to prevent or delay systemic treatments such as chemotherapy. Here we collect together and review these past experiences and the studies currently underway. These types of radiotherapy treatments redefine how we approach extracranial metastatic disease and open up new possibilities for combination therapy with new systemic treatment agents.