Pfizer's bid to expand its oncology portfolio has suffered a setback with the news that the drugs giant has halted a late-stage trial of inotuzumab ozogamicin in patients with an aggressive form of non-Hodgkin's lymphoma due to futility.

The drugs giant has discontinued a Phase III study of the compound, which involved patients with relapsed or refractory CD22+ aggressive NHL who are not candidates for intensive high-dose chemotherapy. In the trial, inotuzumab ozogamicin was administered once-a-month schedule in combination with Roche's Rituxan (rituximab) and compared with either Teva's Treanda (bendamustine) plus rituximab or Eli Lilly's Gemzar (gemcitabine) plus rituximab).

During an interim analysis, an independent data monitoring committee concluded that treatment with inotuzumab ozogamicin plus rituximab would not meet the primary objective of improving overall survival when compared to the comparators. Mace Rothenberg, head of clinical development and medical affairs for Pfizer's oncology business, said "we are working to better understand the findings from this review to determine if there are any patterns of outcome that may help us gain greater understanding of the potential effect of inotuzumab ozogamicin in specific patient subsets".

He added that "haematologic cancers are a complex group of diseases, with more than 70 different types of lymphomas, leukaemias or myelomas that require unique treatment options". Pfizer added that it is continuing another Phase III trial looking at the treatment for acute lymphoblastic leukaemia.

Inotuzumab ozogamicin is an antibody-drug conjugate comprised of a monoclonal antibody targeting CD22, a cell surface antigen expressed on about 90% of B-cell malignancies, linked to a cytotoxic agent. It was developed by Pfizer and the UK's Celltech, which is now owned by UCB of Belgium.