Tumor-associated macrophages (TAMs) modulate response to HER2-targeted agents in a humanized mouse model of breast cancer.

PURPOSE: Tumor-associated macrophages (TAM) may participate to antitumor activity of anti-HER2-targeted therapies (Pertuzumab, Trastuzumab) in breast cancers harbouring HER-2 overexpression through antibody-dependent phagocytosis. Additive antitumor effect of concurrent cytotoxic chemotherapies, including Paclitaxel, may be counterbalanced by alteration in TAM infiltrate. The aim of this study is to evaluate the role of TAM in tumor response to anti-HER2-targeted therapies and chemotherapy in an experimental model of HER2-amplified breast cancer. METHODS: A xenograft mouse model was built by subcutaneous injection of the SKBR-3 human HER2-amplified breast cancer cell line in Hu-CD34+ mice. Animals were randomized to receive weekly administration of Cremophor (control), Trastuzumab+Pertuzumab (TP), and Paclitaxel+Trastuzumab+Pertuzumab (PTP) with or without macrophage depletion with clodronate (C). At week 4, mice were euthanised and tumors were harvested for immunohistochemical analysis of TAM infiltration (RBP-J CD163 and CD68 for M1, M2, and overall TAM, respectively). RESULTS: Tumor size was significantly lower in mice treated with TP, PTP, and PTP+C as compared to control, while no meaningful difference was observed in the TP+C arm. Analysis of TAM infiltrate showed significantly lower CD68 and CD163 expression in PTP, TP+C, and PTP+C as compared to TP and control arm. RBP-J expression was significantly decreased in mice treated with clodronate depletion. CONCLUSIONS: Activity of TP is modulated by TAM infiltrate, that is inhibited by concurrent administration of Paclitaxel. To enhance the effect of anti-HER2-targeted therapies and minimize chemotherapy-related side effects, modulation of TAM should be considered in novel therapeutic combinations.

Benefit of ablative versus palliative-only radiotherapy in combination with nivolumab in patients affected by metastatic kidney and lung cancer.

PURPOSE: Here, we present the results from a retrospective analysis, with the purpose of evaluating the safety and feasibility of nivolumab and radiotherapy (RT) concomitant association in metastatic kidney and lung cancer patients. MATERIALS AND METHODS: From August 2015 until September 2017, we retrospectively observed 20 patients with metastatic lung and renal cell carcinoma who had been initiated therapy with nivolumab and underwent concomitant RT. RT was administered either as an ablative therapy in the oligometastatic/oligoprogressive setting or as palliative-only treatment for symptomatic patients. Data on progression-free and overall survival (PFS and OS), treatment response and adverse events were collected and reported. Comparison between palliative-only and ablative treatments was performed. RESULTS: PFS and OS were 7 and 12.5 months in the entire population, respectively. Oligoprogressive patients treated with ablative intent, compared to patients undergoing RT with palliative-only intent, had statistically longer PFS (11.5 vs 5.2 months, HR 0.42, CI 0.18-0.98, p 0.03) and OS (17.9 vs 10.31 months, HR 0.41 CI 0.16-1.02, p 0.04). Considering only patients treated with ablative intent, 87.5% showed response to treatment, and complete response was reported in 37.5% of cases. Adverse G2-G3 related to combination treatment were reported as follows: 1 gastrointestinal (nausea), 4 breakthrough pain. CONCLUSIONS: Our data showed significant advantage for oligoprogressive patients treated with RT during nivolumab therapy. No safety alert emerged. These results underline the potential synergistic effects of RT and Immune therapy combination. Our analysis prompts further prospective studies exploring the benefit of integrated treatment strategies.