Prepaid expenses consist primarily of prepayments made for research and development work, various professional services, insurance policies, travel, rent, and other miscellaneous prepayments. Total prepaid expenses and other current assets reported on the accompanying consolidated balance sheets at December 31, 2017 and 2016, were both approximately $0.1 million.

One month of rent or approximately $33,000 represents the one-month advance rent placed on the prior McLean, Virginia corporate offices (see Note 7). A security deposit of approximately $15,000 was placed for the new corporate offices in Reston, Virginia (see Note 7). The security deposits at December 31, 2017 and 2016, are reported under the balance sheet caption prepaid expenses and other current assets.