TLR activation of tumor-associated macrophages from ovarian cancer patients triggers cytolytic activity of NK cells.

We analyzed the functional outcome of the interaction between tumor-associated macrophages (TAMs) and natural killer (NK) cells. TAMs from ascites of ovarian cancer patients displayed an alternatively activated functional phenotype (M2) characterized by a remarkably high frequency and surface density of membrane-bound IL-18. Upon TLR engagement, TAMs acquired a classically activated functional phenotype (M1), released immunostimulatory cytokines (IL-12, soluble IL-18), and efficiently triggered the cytolytic activity of NK cells. TAMs also induced the release of IFN-γ from NK cells, which however was significantly lower compared with that induced by in vitro-polarized M2 cells. Most tumor-associated NK cells displayed a CD56(bright) , CD16(neg) or CD56(bright) , CD16(dim) phenotype, and very poor cytolytic activities, despite an increased expression of the activation marker CD69. They also showed downregulation of DNAM-1, 2B4, and NTB-A activating receptors, and an altered chemokine receptor repertoire. Importantly however, when appropriately stimulated, NK cells from the patients, including those cells isolated from ascites, efficiently killed autologous TAMs that expressed low, "nonprotective" levels of HLA class I molecules. Overall, our data show the existence of a complex tumor microenvironment in which poorly cytolytic/immature NK cells deal with immunosuppressive tumor-educated macrophages.

Phase II study of NGR-hTNF, a selective vascular targeting agent, in patients with metastatic colorectal cancer after failure of standard therapy.

BACKGROUND: NGR-hTNF consists of human tumour necrosis factor (hTNF) fused with the tumour-homing peptide Asp-Gly-Arg (NGR), which is able to selectively bind an aminopeptidase N overexpressed on tumour blood vessels. Preclinical antitumour activity was observed even at low doses. We evaluated the activity and safety of low-dose NGR-hTNF in colorectal cancer (CRC) patients failing standard therapies. PATIENTS AND METHODS: Thirty-three patients with progressive disease at study entry received NGR-hTNF 0.8 µg/m(2) given intravenously every 3 weeks. The median number of prior treatment regimens was three (range, 2-5). One-quarter of patients had previously received four or more regimens and two-thirds targeted agents. Progression-free survival (PFS) was the primary study objective. RESULTS: NGR-hTNF was well tolerated. No treatment-related grade 3 to 4 toxicities were detected, most common grade 1 to 2 adverse events being short-lived, infusion-time related chills (50.0%). One partial response and 12 stable diseases were observed, yielding a disease control rate of 39.4% (95% CI, 22.9-57.8%). Median PFS and overall survival were 2.5 months (95% CI, 2.1-2.8) and 13.1 months (95% CI, 8.9-17.3), respectively; whereas in patients who achieved disease control the median PFS and overall survival were 3.8 and 15.4 months, respectively. In an additional cohort of 13 patients treated at same dose with a weekly schedule, there was no increased toxicity and 2 patients experienced PFS longer than 10 months. CONCLUSION: Based on tolerability and preliminary evidence of disease control in heavily pretreated CRC patients, NGR-hTNF deserves further evaluation in combination with standard chemotherapy.

Optimal treatment of metastatic colorectal cancer.

For over 40 years, fluorouracil has been the only drug registered for the treatment of metastatic colorectal cancer. During the past 5 years, combination chemotherapy regimens including either irinotecan or oxaliplatin have proven to be superior to fluorouracil monotherapy in randomized clinical trials, in terms of response rate, progression-free survival and overall survival. Both doublets demonstrated similar efficacy, therefore either combination can be considered standard first-line treatment for metastatic colorectal cancer. Recently, a new orally active fluorouracil analog, capecitabine, and two targeted biological agents, cetuximab and bevacizumab, have been added to the armamentarium of drugs active against metastatic colorectal cancer, thus making the scenario more complex. Moreover, ongoing clinical trials are currently testing new promising molecularly targeted agents. Thus, we are facing a new era in which the rapid clinical development of novel agents is outpacing the ability to perform Phase III clinical trials. At present, there is no single standard treatment suitable for all patients. However, general principles of management can be derived from the available clinical data in order to guide the therapeutic choice and individualize treatment.