ASH 2013: Seattle Genetics Presents Data on Latest Antibody Drug Conjugate

Seattle Genetics has presented interim phase I clinical data from SGN-CD19A, an antibody-drug conjugate (ADC) in development for the treatment of B-cell blood cancers, including acute lymphoblastic leukemia (ALL).

The information was presented at the 55th Annual Meeting of the American Society of Hematology (ASH) in New Orleans.

This was a first-in-human study of SGN-CD19A in relapsed or refractory B-lineage in both ALL and highly aggressive lymphomas.

Direct cancer treatment

SGN-CD19A targets the CD19 protein, which is expressed on the cell surface of many B-cell cancers. As an antibody-drug conjugate, SGN-CD19A works like Seattle Genetics' lead product, Adcetris, delivering the cytotoxic drug payload directly to the cancer cells and avoiding as much damage to healthy cells as possible.

Said Jonathan Drachman, M.D., Chief Medical Officer and Executive Vice President, Research and Development at Seattle Genetics:

The phase 1 trial evaluating SGN-CD19A has demonstrated encouraging early antitumor activity and a generally well-tolerated safety profile among heavily pretreated patients with acute lymphoblastic leukemia and very aggressive types of lymphoma. In addition, multiple complete remissions have been observed in a parallel phase 1 study evaluating SGN-CD19A in aggressive non-Hodgkin lymphoma. Dose-escalation is ongoing in both phase 1 clinical trials, and we plan to report additional data during 2014. Across our six internal clinical development-stage ADCs and more than a dozen collaborator programs, our industry-leading technology continues to empower innovative candidates in development as potential treatment options for patients.

The trial

The presentation include data from 16 adult patients and four pediatric patients with relapsed or refractory B-lineage ALL and highly aggressive lymphoma (including B-cell lymphoblastic lymphoma and Burkitt's lymphoma). The median age of adult patients was 46 years and the median number of prior systemic therapies was two, with six patients (38 percent) having received a prior allogeneic stem cell transplant. The median age of pediatric patients was 14 years and the median number of prior systemic therapies was three, with two patients (50 percent) having received a prior allogeneic stem cell transplant.

Among the adult patients:

• Three patients achieved a complete remission or complete remission with incomplete platelet recovery.
• Eight had resistant disease with clinical benefit or stable disease.
• Five had progressive disease.

There were no responses from any of the four pediatric patients.

This data, from a trial that is ongoing, was presented by Dr. Uma Borate from The University of Alabama in Birmingham, Ala.

Source: ASH