The presence of three water channels (aquaporins, AQP), AQP1, AQP4 and AQP9 were observed in normal brain and several rodent models of brain pathologies. Little is known about AQP distribution in the primate brain and its knowledge will be useful for future testing of drugs aimed at preventing brain edema formation. We studied the expression and cellular distribution of AQP1, 4 and 9 in the non-human primate brain. The distribution of AQP4 in the non-human primate brain was observed in perivascular astrocytes, comparable to the observation made in the rodent brain. In contrast with rodent, primate AQP1 is expressed in the processes and perivascular endfeet of a subtype of astrocytes mainly located in the white matter and the glia limitans, possibly involved in water homeostasis. AQP1 was also observed in neurons innervating the pial blood vessels, suggesting a possible role in cerebral blood flow regulation. As described in rodent, AQP9 mRNA and protein were detected in astrocytes and in catecholaminergic neurons. However additional locations were observed for AQP9 in populations of neurons located in several cortical areas of primate brains. This report describes a detailed study of AQP1, 4 and 9 distributions in the non-human primate brain, which adds to the data already published in rodent brains. This relevant species differences have to be considered carefully to assess potential drugs acting on AQPs non-human primate models before entering human clinical trials.

Metastatic breast cancer is considered an incurable disease. Targeted treatments against the human epidermal growth factor receptor 2 (HER2), however, significantly improve survival in patients with metastatic HER2-positive breast cancer. Some patients may respond with prolonged complete remission. Evidence on safety of long-term trastuzumab and risk of relapse after trastuzumab cessation is limited. We present a case of an 81-year-old patient with HER2-amplified metastatic breast cancer (MBC) in the liver. Following taxane-based chemotherapy in combination with trastuzumab after local treatment resulted in a complete radiological remission after 21 months of trastuzumab maintenance therapy. The patient remains in complete remission 6 years later and continues to receive trastuzumab as maintenance therapy. Prolonged remission in cases with complete response under trastuzumab-based regimens for metastatic HER2-positive breast cancer can be observed in some patients. Reviewing the few available cases published in the literature, these patients share some common characteristics: hormone receptor negative disease and metastases to the liver. There is no evidence that trastuzumab maintenance treatment can be safely interrupted after a certain time period. AbstractIntroduction: Metastatic breast cancer is considered an incurable disease. Targeted treatments against the human epidermal growth factor receptor 2 (HER2), however, significantly improve survival in patients with metastatic HER2-positive breast cancer. Some patients may respond with prolonged complete remission. Evidence on safety of long-term trastuzumab and risk of relapse after trastuzumab cessation are limited. Case presentation: We present a case of an 81-year-old patient with HER2-amplified metastatic breast cancer (MBC) in the liver. Following taxane-based chemotherapy in combination with trastuzumab after local treatment resulted in a complete radiological remission after 21 months of trastuzumab maintenance therapy. The patient remains in complete remission 6 years later and continues to receive trastuzumab as maintenance therapy. Conclusion: Prolonged remission in cases with complete response under trastuzumab based regimens for metastatic HER2-positive breast cancer can be observed in some patients. Reviewing the few available cases published in the literature, these patients share some common characteristics: hormone receptor negative disease and metastases to the liver. There is no evidence that trastuzumab maintenance treatment can be safely interrupted after a certain time period.