I do not have access to the full text of the article "Biting the Tail of CAR-T for Relapsed Multiple Myeloma" from the New England Journal of Medicine dated February 19, 2026. The search results provided contain information about CAR-T therapy for multiple myeloma from other sources, but not from the specific article you asked to summarize. In order to create an accurate and factual summary as per your requirements, I would need access to the full text of this particular article. Without it, I could not guarantee that the summary would contain only verified facts from the given source.