The use of daratumumab for POEMS syndrome is not supported by clinical trials of any kind. In fact, the only report I am finding is a letter by an author at Mayo Clinic. There are some case reports, but no higher quality evidence. As such, it is E/I and not medically necessary.
Maliha Khan, MD, Katie Stone, BS, Frits van Rhee, MD, Ph, Daratumumab for POEMS Syndrome
Mayo Clinic Proceedings Volume 93, Issue 4, April 2018, Pages 542-544 Mayo Clinic Proceedings
Kuwabara S, et al. Cochrane Database Syst Rev. 2012,Treatment for POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes) syndrome.. Kuwabara S, Dispenzieri A, Arimura K, Misawa S, Nakaseko C. Cochrane Database Syst Rev. 2012 Jun 13;(6)