yes, makes sense for a review article to be embargoed. Without L the review about DC cells is incomplete. Must be DCVaxL portion of the article is embargoed and the authors are hoping L gets approved in between and are free to include review of L before Feb 2019.
No journals embargo actual articles for a year. This may be a terminology issue. Many journals have subscription only access until a year after publication. By law, if the study was NIH funded, the publisher has to provide open access to the article after that year of "embargo." No data is being witheld for a year.