Long-term responders to nivolumab in previously treated advanced renal cell carcinoma: a sub-analysis of meet-URO15 study.

BACKGROUND: Although nivolumab prolongs overall survival (OS) in pretreated patients with metastatic renal cell carcinoma (mRCC), underlining clinical and biological features of long-term responses are still to be determined. This study aims to investigate clinical and pathological characteristics of mRCC patients who achieved long-term responses during nivolumab treatment. MATERIALS AND METHODS: A retrospective analysis was performed on mRCC patients receiving nivolumab as second or further therapy line between May 2016 and January 2019 in 34 Italian Oncology Centres. Outcome assessments and logistic regression were performed to evaluate factors influencing long-term responses. RESULTS: A total of 571 patients with a median age of 61 years (range 17-85) were included in the analysis. With a median follow-up of 22.1 (1.0-89.0) months, 23.1% of patients were 2-year progression-free on treatment with nivolumab, hence they were categorized as long-term responders. Baseline characteristics, including age, gender, and histology, were similar between long- and short-term responders. Karnofsky Performance Status ≥ 80% was significantly associated with long-term response (p = 0.02), while bone metastases (p = 0.03), International mRCC Database Consortium intermediate-poor risk (p < 0.01) and Neutrophil-to-Lymphocyte Ratio ≥ 3.2 (p = 0.02) were associate with short-term responses. Long-term responders exhibited a median progression-free survival of 55.0 months versus 4.0 months of the short-term responders. The median OS was not reached in long-term responders while it was 17.0 months for short*term responders. CONCLUSION: This retrospective analysis sheds light on factors associated with long-term response to nivolumab in mRCC. Understanding these clinical features will be essential for selecting patients who may mostly benefit from immunotherapy.

Analyses of tumor microenvironment in patients with advanced renal cell carcinoma receiving immunotherapy (Meet-URO 18 study).

Introduction: The Meet-URO 18 study is a multicentric study of patients with metastatic renal cell carcinoma receiving nivolumab in the second-line and beyond, categorized as responders (progression-free survival ≥ 12 months) and non-responders (progression-free survival < 3 months). Areas covered: The current study includes extensive immunohistochemical analysis of T-lineage markers (CD3, CD4, CD8, CD8/CD4 ratio), macrophages (CD68), ph-mTOR, CD15 and CD56 expression on tumor cells, and PD-L1 expression, on an increased sample size including 161 tumor samples (113 patients) compared with preliminary presented data. Responders' tumor tissue (n = 90; 55.9%) was associated with lower CD4 expression (p = 0.014), higher CD56 expression (p = 0.046) and higher CD8/CD4 ratio (p = 0.030). Expert opinion/commentary: The present work suggests the regulatory role of a subpopulation of T cells on antitumor response and identifies CD56 as a putative biomarker of immunotherapy efficacy.

Analyses of tumor microenvironment in patients with advanced renal cell carcinoma receiving immunotherapy (Meet-URO 18 study).

Introduction: The Meet-URO 18 study is a multicentric study of patients with metastatic renal cell carcinoma receiving nivolumab in the second-line and beyond, categorized as responders (progression-free survival ≥ 12 months) and non-responders (progression-free survival < 3 months). Areas covered: The current study includes extensive immunohistochemical analysis of T-lineage markers (CD3, CD4, CD8, CD8/CD4 ratio), macrophages (CD68), ph-mTOR, CD15 and CD56 expression on tumor cells, and PD-L1 expression, on an increased sample size including 161 tumor samples (113 patients) compared with preliminary presented data. Responders' tumor tissue (n = 90; 55.9%) was associated with lower CD4 expression (p = 0.014), higher CD56 expression (p = 0.046) and higher CD8/CD4 ratio (p = 0.030). Expert opinion/commentary: The present work suggests the regulatory role of a subpopulation of T cells on antitumor response and identifies CD56 as a putative biomarker of immunotherapy efficacy.

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Apalutamide-induced lichenoid reaction in a patient with non-metastatic castrate-resistant prostate cancer.

INTRODUCTION: Apalutamide is an oral selective androgen receptor inhibitor, approved by the FDA for the treatment of patients with non-metastatic, castration-resistant prostate cancer (M0 CRPC) at high risk of developing metastases and for patients with metastatic castration-sensitive prostate (mHSPC) in association with androgen deprivation therapy (ADT). In the registration studies, skin reactions were reported among the most common side effects and as an adverse event of special interest. CASE REPORT: Apalutamide-induced rash includes a wide spectrum of different types of skin reactions, but few cases reports and case series have described this adverse event. Here, we report an M0 CRPC patient who experienced a rare skin adverse event, a lichenoid reaction. MANAGEMENT & OUTCOME: After 4 months of therapy with apalutamide, the patient reported dorsal pricking and dry skin. Lichenoid reaction was confirmed histologically and its correlation to the drug was demonstrated after pursuing a multidisciplinary approach. DISCUSSION: To our knowledge, this is one of the first cases of Apalutamide-related lichenoid reaction and this clinical case showed the relevance of a multidisciplinary management when assessing drug-related adverse events. A broader knowledge of the spectrum of drug-related reactions would allow for a better diagnosis and therapy management by both physicians and patients.

Rare anti-VEGFR therapy-induced toxicity and long-term response to immunotherapy in a rare non-clear cell renal cell carcinoma patient.

Advanced non-clear cell renal cell carcinoma (nccRCC) has a poor prognosis and clinical data on the therapeutic options currently available, including immunotherapy, are generally limited highlighting an unmet clinical need. Moreover, the onset of rare adverse events raises the need of a better therapeutic management of limited treatment options. We report the clinical case of a 63-year-old man with the diagnosis of metastatic mucinous tubular and spindle cell carcinoma, a rare nccRCC, with sarcomatoid differentiation who developed two episodes of posterior reversible encephalopathy syndrome (PRES) to first-line sunitinib. It appeared after 5 months the start of the targeted therapy and reappeared at the reintroduction of the therapy. PRES is a rare and unusual adverse event to anti-vascular endothelial growth factor receptor (VEGFR) therapies, which is characterized by acute neurological disorders along with typical changes on neurological imaging, especially MRI. Moreover, this rare histotype of RCC experienced a long-term response to immunotherapy which is lasting more than 2 years. This clinical case is interesting for its rarity as a rare neurological adverse event developed twice in a rare type of RCC which also experienced an unusual long-term benefit to immunotherapy.

Interventional Ultrasound in Dermatology: A Pictorial Overview Focusing on Cutaneous Melanoma Patients.

Cutaneous melanoma incidence is increasing worldwide, representing an aggressive tumor when evolving to the metastatic phase. High-resolution ultrasound (US) is playing a growing role in the assessment of newly diagnosed melanoma cases, in the locoregional staging prior to the sentinel lymph-node biopsy procedure, and in the melanoma patient follow-up. Additionally, US may guide a number of percutaneous procedures in the melanoma patients, encompassing diagnostic and therapeutic modalities. These include fine needle cytology, core biopsy, placement of presurgical guidewires, aspiration of lymphoceles and seromas, and electrochemotherapy.

Beyond BRCA: The Emerging Significance of DNA Damage Response and Personalized Treatment in Pancreatic and Prostate Cancer Patients.

The BRCA1/2 germline and/or somatic pathogenic variants (PVs) are key players in the hereditary predisposition and therapeutic response for breast, ovarian and, more recently, pancreatic and prostate cancers. Aberrations in other genes involved in homologous recombination and DNA damage response (DDR) pathways are being investigated as promising targets in ongoing clinical trials. However, DDR genes are not routinely tested worldwide. Due to heterogeneity in cohort selection and dissimilar sequencing approaches across studies, neither the burden of PVs in DDR genes nor the prevalence of PVs in genes in common among pancreatic and prostate cancer can be easily quantified. We aim to contextualize these genes, altered in both pancreatic and prostate cancers, in the DDR process, to summarize their hereditary and somatic burden in different studies and harness their deficiency for cancer treatments in the context of currently ongoing clinical trials. We conclude that the inclusion of DDR genes, other than BRCA1/2, shared by both cancers considerably increases the detection rate of potentially actionable variants, which are triplicated in pancreatic and almost doubled in prostate cancer. Thus, DDR alterations are suitable targets for drug development and to improve the outcome in both pancreatic and prostate cancer patients. Importantly, this will increase the detection of germline pathogenic variants, thereby patient referral to genetic counseling.

Multiple systemic treatment options in a patient with malignant tenosynovial giant cell tumour.

Tenosynovial giant cell tumour (TGCT) is a group of rare soft tissues neoplasia affecting synovial joints, bursae and tendon sheaths and is classified as localized type or diffuse type. The diffuse type (TGCT-D), also known as 'pigmented villonodular (teno)synovitis' is characterized by local aggressivity, with invasion and destruction of adjacent soft-tissue structures, and high local recurrence rate. Radical surgery remains the standard therapy while adjuvant radiotherapy may help to control local spread. Malignant TGCT is characterized by high rate of local recurrences and distant metastasis. Few cases of malignant TGCT and very few evidences on systemic therapies are described in the literature, so, to date, no systemic treatment is approved for this rare disease. We report the case of a malignant TGCT patient treated with many different systemic therapies, including chemotherapy and tyrosine-kinase inhibitors, and performed a review of the literature on the systemic treatment options of this rare tumour.

Negative pressure surgical management after pathological scar surgical excision: a first report.

Wound dehiscence is a surgical complication caused by the application of opposing and distracting forces tending to pull apart the suture line. In recent years, a novel negative pressure surgical management system has been developed to prevent surgical wound complications. This system creates a closed environment that removes exudates and other potentially infectious material, protects the surgical site from external contamination, provides support in holding the edges of the incision together and promotes wound healing. In this study, we describe our first experience with Prevena™, a closed incision negative pressure management system used on suture line following wide pathological scars excision for the prevention of postoperative wound dehiscence. Eight patients with wide and mature pathological skin scars were treated with Prevena™. The device was positioned directly after surgical correction for 8 days with a continuous application of -125 mmHg negative pressure. All treated patients had no postoperative surgical wound dehiscence. In one case, a limit of the device was represented by its poor adherence on hairy surface, hampering the maintenance of an appropriate local negative pressure. In another case, suture line was longer than Prevena™ foam and it was covered partially. Prevena™ system appears to be safe, easy to use and may represent a support technique to wide pathological skin scars surgical correction.

Cross-trial comparisons for the adjuvant treatment of MSI colorectal cancer: dare to dream the future scenarios.

The remarkable outcomes achieved with neoadjuvant checkpoint inhibitors for patients diagnosed with MSI colorectal cancer hold the potential to revolutionize the treatment landscape in this context. Specifically, the combination of nivolumab plus ipilimumab in colon cancer and dostarlimab in rectal cancer has led to an unprecedented rate of complete pathological and clinical responses. Notably, these responses have been further substantiated by the absence of relapses, with a 0% relapse rate observed during the first year of follow-up. The significance of these achievements becomes even more apparent when compared to the relatively high relapse rates, ranging from 11% to 28%, observed in MSI colorectal cancer cases treated neoadjuvantly with chemo(radio)therapy. However, it is crucial to exercise caution when interpreting such exceptional responses in oncology, especially within a short follow-up period. The future implications of these findings will depend on how the data mature over time. In this manuscript, we attempt to explore the potential scenarios that may unfold in the near future.

Clinical high risk for psychosis and service disengagement: Incidence and predictors across 2 years of follow-up.

BACK: Service disengagement is common in subjects at CHR-P (clinical high risk for psychosis), potentially worsening daily functioning and increasing the duration of untreated psychosis. That is why to identify baseline predictors of service disengagement could help better tailoring follow-up on every CHR-P individual. AIMS: Since there are few studies on this topic, the goals of this examination were: (1) to calculate service disengagement rates in a CHR-P sample along 2-years of follow-up; and (2) to examine the most relevant predictive factors of disengagement at baseline. METHODS: All young CHR-P participants were enrolled within the 'Parma At-Risk Mental States' (PARMS) protocol. At entry, the Global Assessment of Functioning (GAF) scale and the positive and negative syndrome scale (PANSS) were completed. Cox regression analyses were used. RESULTS: Hundred and eighty CHR-P subjects were recruited in this examination. During the follow-up, a 2-year service disengagement prevalence rate of 15% was observed. A statistically robust predictive factor of service disengagement was a lower prescription of antidepressant drug at entry. Other relevant baseline predictive factors were migrant status, higher GAF score, lower levels of anxious-depressive symptoms and a lower acceptance of psychosocial interventions. DISCUSSION: Baseline presence of anxious-depressive features in CHR-P individuals could favour engagement to specialized EIP services. However, implementing strategies to improve patients' motivation and involvement in care are needed.

Hyperthyroidism in non-seminomatous testicular germ cell tumors: two case reports and literature review.

Background: Human chorionic gonadotropin (hCG)-induced hyperthyroidism is a rare paraneoplastic syndrome observed in non-seminomatous testicular germ cell tumors, due to a cross-reaction between the ß-subunit of hCG with the thyroid-stimulating hormone receptor. The precise prevalence of this paraneoplastic phenomenon is unclear as, in the majority of cases, hyperthyroidism remains subclinical. Case presentation: Here, we present two cases of advanced metastatic non-seminomatous testicular germ cell tumors where patients exhibited signs and symptoms of thyrotoxicosis at primary diagnosis due to excessive serum ß-hCG elevation, with complete remission of symptomatology after the start of oncological treatments and no signs of relapse at the time of publication of this report. Additionally, we provide a comprehensive review of the existing literature concerning this uncommon occurrence. Conclusion: Despite being a rare event, the presence of hyperthyroidism or thyrotoxicosis without clear etiology in a young man should lead to consider less frequent causes such as testicular tumors. Even if patients typically have mild symptoms that resolve after chemotherapy, in rare cases, it can be a life-threatening condition that requires prompt recognition and specific intervention.

A red blood cell-based score in the prognostication of patients with metastatic RCC of the Meet-URO 15 study.

Aims: Anemia, mean corpuscular volume and red cell distribution width may have some effects on survival outcomes of metastatic renal cell carcinoma (mRCC) patients and are incorporated in a red blood cell (RBC)-based score. Its validity in prognostication of mRCC patients treated with second-line nivolumab was assessed. Patients and methods: Retrospective analysis using Meet-URO-15 cohort of mRCC patients receiving nivolumab in the second-line setting or beyond. Outcomes were overall survival (OS) and progression-free survival (PFS). Results: A total of 390 patients were included. Significant differences in OS and PFS between RBC-based score groups, with group 1 (2 or 3 of the RBC-related prognostic factors) having longer OS (median 29.5 months, 95% CI: 23.1-35.9, versus 11.5 months, 95% CI: 8.5-22.6; p < 0.001) and PFS (7.5 months, 95% CI: 5.5-10.2, versus 4.2 months, 95% CI: 3.3-5.9; p = 0.040) than those in group 0 (0 or 1 RBC-related prognostic factors). Belonging to group 1 independently predicted OS (hazard ratio: 0.65, 95% CI: 0.50-0.85; p = 0.002) but not PFS (hazard ratio: 0.89, 95% CI: 0.70-1.14, p = 0.370) or disease response (OR 0.68, 95% CI: 0.41-1.10; p = 0.118) at multivariable analysis. Conclusion: RBC-based group scores independently predicted OS in mRCC patients treated with nivolumab.

This study looked at how certain blood cell measurements (anemia, mean corpuscular volume, red cell distribution width) affect survival in patients with metastatic renal cell carcinoma who are treated with nivolumab, an immunotherapy drug. Researchers analyzed data from 390 patients who received nivolumab as a second-line treatment or beyond. They divided patients into groups based on their blood cell scores. They found that patients with higher scores had better overall survival and progression-free survival compared with those with lower scores. Specifically, patients with better scores lived longer. The study concluded that these scores can help predict survival in these patients treated with nivolumab.

Prognostic Stratification by the Meet-URO Score in Real-World Older Patients With Metastatic Renal Cell Carcinoma (mRCC) Receiving Cabozantinib: A Subanalysis of the Prospective ZEBRA Study (Meet-URO 9).

BACKGROUND: The addition of neutrophil to lymphocyte ratio (NLR) and bone metastases to the IMDC classification provided by the Meet-URO score, resulted in higher prognostic accuracy in metastatic renal cell carcinoma (mRCC) patients receiving ≥2nd line nivolumab or cabozantinib in 2 retrospective analyses and 1st line nivolumab-ipilimumab in an expanded access programme. Prognostic estimates for older mRCC patients might be key for clinical decision-making. METHODS: The outcome of real-world older (≥70 years) mRCC patients treated with any line cabozantinib within the multicenter observational prospective ZEBRA (Meet-URO 9) study was analyzed according to the baseline Meet-URO score. The primary endpoint was overall survival (OS). The discriminative ability by Harrell's c-index and calibration were assessed to compare the Meet-URO and IMDC scores. RESULTS: A total of 104 mRCC patients received cabozantinib as 1st (38%), 2nd (20%), or ≥3rd (41%) line. With a median follow-up of 11.2 months, the median OS (mOS) was of 18.4 months. According to the IMDC score, favorable (15%), intermediate (65%) and poor-risk (19%) patients had a mOS not reached, of 15.6 and 5.7 months respectively (p = .011). According to the Meet-URO score groups, mOS was not reached in both group 1 (10%) and group 2 (25%), while in group 3 (33%), group 4 (25%) and group 5 (8%) mOS was of 13.6, 12.5, and 3.7 months, respectively (p < .001). The discriminative ability of the Meet-URO score was maintained by merging groups 1 to 2 vs. 3 to 4 vs. 5 (p < .001). The Meet-URO score (with either the original 5-group stratification or the modified 3-group one) showed higher accuracy than the IMDC score (c-index of 0.686 and 0.676 vs. 0.622). CONCLUSION: This analysis confirmed the prognostic accuracy of the Meet-URO score in older mRCC patients treated with cabozantinib and its role as a convenient tool for informing the patient and clinical decisions.

Lentiviral Gene Therapy for Mucopolysaccharidosis II with Tagged Iduronate 2-Sulfatase Prevents Life-Threatening Pathology in Peripheral Tissues But Fails to Correct Cartilage.

Deficiency of iduronate 2-sulfatase (IDS) causes Mucopolysaccharidosis type II (MPS II), a lysosomal storage disorder characterized by systemic accumulation of glycosaminoglycans (GAGs), leading to a devastating cognitive decline and life-threatening respiratory and cardiac complications. We previously found that hematopoietic stem and progenitor cell-mediated lentiviral gene therapy (HSPC-LVGT) employing tagged IDS with insulin-like growth factor 2 (IGF2) or ApoE2, but not receptor-associated protein minimal peptide (RAP12x2), efficiently prevented brain pathology in a murine model of MPS II. In this study, we report on the effects of HSPC-LVGT on peripheral pathology and we analyzed IDS biodistribution. We found that HSPC-LVGT with all vectors completely corrected GAG accumulation and lysosomal pathology in liver, spleen, kidney, tracheal mucosa, and heart valves. Full correction of tunica media of the great heart vessels was achieved only with IDS.IGF2co gene therapy, while the other vectors provided near complete (IDS.ApoE2co) or no (IDSco and IDS.RAP12x2co) correction. In contrast, tracheal, epiphyseal, and articular cartilage remained largely uncorrected by all vectors tested. These efficacies were closely matched by IDS protein levels following HSPC-LVGT. Our results demonstrate the capability of HSPC-LVGT to correct pathology in tissues of high clinical relevance, including those of the heart and respiratory system, while challenges remain for the correction of cartilage pathology.

Prognostic value of type of prior TKI in pretreated metastatic renal cell carcinoma patients receiving nivolumab.

Aim: To define the prognostic significance of first-line TKI in mRCC patients receiving nivolumab.Materials and methods: A total of 571 mRCC patients who received ≥second line nivolumab were included in this subanalysis. The correlation between prior TKI (sunitinib vs. pazopanib) and overall response rate (ORR), disease control rate, progression-free survival and overall survival were investigated. Additionally, the impact of TKI choice according to the International Metastatic RCC Database Consortium prognostic score was examined.Results: There was no significant difference between sunitinib and pazopanib groups in terms of mPFS, mOS, overall response rate and disease control rate. Moreover, no difference between sunitinib and pazopanib was found according to the International Metastatic RCC Database Consortium prognostic score.Conclusion: There is no conclusive evidence favoring pazopanib or sunitinib treatment before initiating nivolumab therapy in metastatic renal cell carcinoma patients.

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Time to strategy failure and treatment beyond progression in pretreated metastatic renal cell carcinoma patients receiving nivolumab: post-hoc analysis of the Meet-URO 15 study.

Background: Immunotherapies exhibit peculiar cancer response patterns in contrast to chemotherapy and targeted therapy. Some patients experience disease response after initial progression or durable responses after treatment interruption. In clinical practice, immune checkpoint inhibitors may be continued after radiological progression if clinical benefit is observed. As a result, estimating progression-free survival (PFS) based on the first disease progression may not accurately reflect the actual benefit of immunotherapy. Methods: The Meet-URO 15 study was a multicenter retrospective analysis of 571 pretreated metastatic renal cell carcinoma (mRCC) patients receiving nivolumab. Time to strategy failure (TSF) was defined as the interval from the start of immunotherapy to definitive disease progression or death. This post-hoc analysis compared TSF to PFS and assess the response and survival outcomes between patients treatated beyond progression (TBP) and non-TBP. Moreover, we evaluated the prognostic accuracy of the Meet-URO score versus the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) score based on TSF and PFS. Results: Overall, 571 mRCC patients were included in the analysis. Median TSF was 8.6 months (95% CI: 7.0 - 10.1), while mPFS was 7.0 months (95% CI: 5.7 - 8.5). TBP patients (N = 93) had significantly longer TSF (16.3 vs 5.5 months; p < 0.001) and overall survival (OS) (34.8 vs 17.9 months; p < 0.001) but similar PFS compared to non-TBP patients. In TBP patients, a median delay of 9.6 months (range: 6.7-16.3) from the first to the definitive disease progression was observed, whereas non-TBP patients had overlapped median TSF and PFS (5.5 months). Moreover, TBP patients had a trend toward a higher overall response rate (33.3% vs 24.3%; p = 0.075) and disease control rate (61.3% vs 55.5%; p = 0.31). Finally, in the whole population the Meet-URO score outperformed the IMDC score in predicting both TSF (c-index: 0.63 vs 0.59) and PFS (0.62 vs 0.59). Conclusion: We found a 2-month difference between mTSF and mPFS in mRCC patients receiving nivolumab. However, TBP patients had better outcomes, including significantly longer TSF and OS than non-TBP patients. The Meet-URO score is a reliable predictor of TSF and PFS.

Use of new microcirculation software allows the demonstration of dermis vascularization.

AIMS: Current ultrasound (US) Doppler techniques cannot demonstrate the vascularization of the dermis. The purpose of this study was to investigate whether the new Superb Vascular Imaging (SMI) and Microvascular Flow (MV-Flow) techniques improve the detection of normal dermis vessels. SMI and MV-Flow were compared side-by-side to conventional power-Doppler (PD) imaging. METHODS: By using US, 50 healthy volunteers were evaluated at level of five body areas: forehead, forearm, palm, buttock, and thigh. Two off-site operators evaluated the images to assess the difference between SMI and PD imaging and between MV-Flow and PD imaging in terms of dermis flow amount. A 0-3 scoring system was adopted. RESULTS: SMI scored grade 0 in 0% of body areas, grade 1 in 58%, grade 2 in 33%, and grade 3 in 9%. In comparison with SMI, PD scored grade 0 in 38% of body areas, grade 1 in 56%, grade 2 in 6%, and grade 3 in 0%. MV-Flow scored grade 0 in 0% of body areas, grade 1 in 52%, grade 2 in 43%, and grade 3 in 6%. Comparted to MV-Flow, PD scored grade 0 in 53% of body areas, grade 1 in 34%, grade 2 in 13%, and grade 3 in 0%. The difference in terms of sensitivity was statistically significant for all the body areas investigated. CONCLUSIONS: We found both SMI and MV-Flow to be superior to PD imaging and capable to demonstrate normal vascularization of the dermis.

Molecular Tailored Therapeutic Options for Advanced Gastrointestinal Stromal Tumors (GISTs): Current Practice and Future Perspectives.

Gastrointestinal stromal tumors (GISTs) are one of the most common mesenchymal tumors characterized by different molecular alterations that lead to specific clinical presentations and behaviors. In the last twenty years, thanks to the discovery of these mutations, several new treatment options have emerged. This review provides an extensive overview of GISTs' molecular pathways and their respective tailored therapeutic strategies. Furthermore, current treatment strategies under investigation and future perspectives are analyzed and discussed.

The role of immunotherapy in microsatellites stable metastatic colorectal cancer: state of the art and future perspectives.

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths worldwide, despite several advances has been achieved in last decades. Few prognostic and predictive biomarkers guide therapeutic choice in metastatic CRC (mCRC), among which DNA mismatch repair deficiency and/or microsatellite instability (dMMR/MSI) holds a crucial role. Tumors characterized by dMMR/MSI benefit from immune checkpoint inhibitors. However, most of the mCRC patients (around 95%) are microsatellite stable (MSS), thereby intrinsically resistant to immunotherapy. This represents a clear unmet need for more effective treatments in this population of patients. In this review, we aim to analyze immune-resistance mechanisms and therapeutic strategies to overcome them, such as combinations of immunotherapy and chemotherapy, radiotherapy or target therapies specifically in MSS mCRC. We also explored both available and potential biomarkers that may better select MSS mCRC patients for immunotherapy. Lastly, we provide a brief overview on future perspectives in this field, such as the gut microbiome and its potential role as immunomodulator.