SAR3419, which entered clinical trials just recently, is an ADC comprised of an antibody that targets CD19 and the toxic agent DM4. CD19 is broadly expressed through many types of B-lymphoid malignancies but not on normal B cells. To date, several anti CD19 antibodies were evaluated pre-clinically as well as in clinical trials but did not show a great deal of clinical effect. In addition, CD19 was shown to internalize after an antibody binds it, which makes it a suitable target for Antibody-drug conjugates.

SAR3419 is being developed by Sanofi-Aventis for the treatment B-cell hematological malignancies, including non-Hodgkin’s lymphoma [NHL] and acute lymphoblastic leukemia [ALL]. The huge potential in this market can be demonstrated by the success of Genentech’s Rituxan^®, which had worldwide sales of just under 4$ billion in 2006. Since Rituxan’s target (CD20) is different than SAR3419’s, these agents are not necessarily competitors, but even may have a synergistic effect. Even if SAR3419 is found to be clinically active, it might face tough competition from Micromet’s (MITI) promising anti CD19 bispecific antibody, MT103, which has already shown promising results among NHL patients.

Author is long IMGN