RIVA – a phase IIa study of rituximab and varlilumab in relapsed or refractory B-cell malignancies: study protocol for a randomized controlled trial oleh Sean H. Lim, Kim M. Linton, Graham P. Collins, Joke Dhondt, Joshua Caddy, Liz Rossiter, Karan Vadher, Keira Fines, Laura E. Rogers, Diana Fernando, Louise Stanton, Andrew J. Davies, Peter W. M. Johnson, Gareth Griffiths