Over the past decade, growing evidence indicates that the tumor microenvironment (TME) contributes with genomic/epigenomic aberrations of malignant cells to enhance cancer cells survival, invasion, and dissemination. Many factors, produced orde novosynthesized by immune, stromal, or malignant cells, acting in a paracrine and autocrine fashion, remodel TME and the adaptive immune response culminating in metastasis. Taking into account the recent accomplishments in the field of immune oncology and using metastatic colorectal cancer (mCRC) as a model, we propose that the evasion of the immune surveillance and metastatic spread can be achieved through a number of mechanisms that include (a) intrinsic plasticity and adaptability of immune and malignant cells to paracrine and autocrine stimuli or genotoxic stresses; (b) alteration of positional schemes of myeloid-lineage cells, produced by factors controlling the balance between tumour-suppressing and tumour-promoting activities; (c) acquisition by cancer cells of aberrant immune-phenotypic traits (NT5E/CD73, CD68, and CD163) that enhance the interactions among TME components through the production of immune-suppressive mediators. These properties may represent the driving force of metastatic progression and thus clinically exploitable for cancer prevention and therapy. In this review we summarize results and suggest new hypotheses that favour the growing impact of tumor-infiltrating immune cells on tumour progression, metastasis, and therapy resistance.

Nano albumin bound-paclitaxel in pancreatic cancer: Current evidences and future directions

Data from molecular profiles of tumors and tumor associated cells provide a model in which cancer cells can acquire the capability of avoiding immune surveillance by expressing an immune-like phenotype. Recent works reveal that expression of immune antigens (PDL1, CD47, CD73, CD14, CD68, MAC387, CD163, DAP12, and CD15) by tumor cells “immune resistance,” combined with prometastatic function of nonmalignant infiltrating cells, may represent a strategy to overcome the rate-limiting steps of metastatic cascade through (a) enhanced interactions with protumorigenic myeloid cells and escape from T-dependent immune response mediated by CD8+ and natural killer (NK) cells; (b) production of immune mediators that establish a local and systemic tumor-supportive environment (premetastatic niche); (c) ability to survive either in the peripheral blood as circulating tumor cells (CTCs) or at the metastatic site forming a cooperative prometastatic loop with foreign “myeloid” cells, macrophages, and neutrophils, respectively. The development of cancer-specific “immune resistance” can be orchestrated either by cooperation with tumor microenvironment or by successive rounds of genetic/epigenetic changes. Recognition of the applicability of this model may provide effective therapeutic avenues for complete elimination of immune-resistant metastatic cells and for enhanced antitumor immunity as part of a combinatorial strategy.

In the last decades, we have progressively observed an improvement in therapeutic options for metastatic colorectal cancer (mCRC) treatment with a progressive prolongation of survival. mCRC prognosis still remains poor with low percentage of 5-year survival. Targeted agents have improved results obtained with standard chemotherapy. Angiogenesis plays a crucial role in colorectal cancer growth, proliferation, and metastasization and it has been investigated as a potential target for mCRC treatment. Accordingly, novel antiangiogenic targeted agents bevacizumab, regorafenib, and aflibercept have been approved for mCRC treatment as the result of several phase III randomized trials. The development of a tumor permissive microenvironment via the aberrant expression by tumor cells of paracrine factors alters the tumor-stroma interactions inducing an expansion of proangiogenic signals. Recently, the VELOUR study showed that addition of aflibercept to FOLFIRI regimen as a second-line therapy for mCRC improved significantly OS, PFS, and RR. This molecule represents a valid second-line therapeutic option and its peculiar ability to interfere with placental growth factor (PlGF)/vascular endothelial growth factor receptor 1 (VEGFR1) axis makes it effective in targeting angiogenesis, inflammatory cells and in overcoming resistances to anti-angiogenic first-line treatment. Here, we discuss about Aflibercept peculiar ability to interfere with tumor microenvironment and angiogenic pathway.

Pancreatic adenocarcinoma is an aggressive disease with poor prognosis. In a randomized phase III trial, combination of Nab-paclitaxel (Nab-P) plus gemcitabine showed superior activity and efficacy in first-line treatment compared with gemcitabine alone. Nab-P is not dispensed in Italy; however, we obtained this drug from our Ethics Committee for compassionate use. The aim of this study was to evaluate the efficacy and safety profile of this Nab-P and gemcitabine combination in a cohort of patients treated outside clinical trials. From January 2012 to May 2014, we included 41 patients with advanced pancreatic adenocarcinoma receiving combination of 125 mg/m2 Nab-P and 1 g/m2 gemcitabine on days 1, 8 and 15 of a 28-day cycle, as first-line treatment. Median age of patients was 67 (range 41–77) years, and 11 patients were aged ≥70 years. Eastern Co-operative Oncology Group performance status was 0 or 1 in 32 patients (78 %) and 2 in nine patients (22 %). Primary tumor was located in the pancreatic head or body/tail in 24 (58.5 %) and 17 (41.5 %) patients, respectively, and nine patients had received biliary stent implantation before starting chemotherapy. Median carbohydrate antigen 19–9 level was 469 U/l (range 17.4–61546 U/l) and 29 patients (70.7 %) had referred pain at the time of diagnosis. Patients received a median six cycles (range 1–14) of treatment. Overall response rate was 36.6 %; median progression-free survival was 6.7 months [(95 % confidence interval (CI) 5.966–8.034), and median overall survival was 10 months (95 % CI 7.864–12.136). Treatment was well tolerated. No grade 4 toxicity was reported. Grade 3 toxicity included neutropenia in 10 patients (24.3 %), thrombocytopenia in five (12 %), anemia in three (7.3 %), diarrhea in four (9.7 %), nausea and vomiting in two (4.9 %), and fatigue in six (14.6 %). Finally, pain control was achieved in 24 of 29 patients (82.3 %) with a performance status improvement of 10 % according to the Karnofsky scale. Our results confirm that combination of gemcitabine plus Nab-P is effective both in terms of overall response rate, progression-free survival and overall survival, with a good safety profile.

Targeting the epidermal growth factor receptor (EGFR) either alone or in combination with chemotherapy in patients with RAS wild type metastatic colorectal cancer (mCRC) has revolutionized the treatment of CRC, but with less results than initially envisaged. In recent years, the discovery of multiple pathways leading to the escape from anti-EGFR therapy has revealed an enormous complexity and heterogeneity of human CRC due to the intrinsic genomic instability and immune/cancer cell interaction. Therefore, understanding the mechanistic basis of acquired resistance to targeted therapies represents a major challenge to improve the clinical outcomes of patients with CRC. The latest findings strongly suggest that complex molecular alterations coupled with changes of the immune tumor microenvironment may substantially contribute to the clinical efficacy of EGFR antagonist. In this review, we discuss the most recent findings that contribute to both primary and acquired anti-EGFR therapy resistance. In addition, we analyze how strategies aiming to enhance the favorable effects in the tumor microenvironment may contribute to overcome resistance to EGFR therapies.