Oxford BioMedica has expanded its 5T4 tumor antigen therapeutics collaboration with Pfizer by granting the latter nonexclusive rights to the diagnostic use of antibodies against the antigen and an option to commercialize a 5T4-based diagnostic. The firm could earn up to $4 million in up front, development, and commercialization milestones plus revenues relating to Pfizer’s use of 5T4 antibodies for diagnostic applications.
Expansion of BioMedica and Pfizer’s agreement relates directly to the U.S. drug giant’s ongoing preclinical development of a 5T4-targeted antibody therapeutic. The original therapeutics-focused agreement was signed back in 2001 between BioMedica and Wyeth, which Pfizer acquired in 2009. It granted Wyeth global rights to market antibodies targeting 5T4 for all human cancer indications.
BioMedica could earn up to $24 million through up front payments, license option fees, and milestones relating to the therapeutics-focused part of the deal. The initial product being developed by Pfizer is a humanized mAb linked to the anticancer agent, calicheamicin. BioMedica says that its partner may submit an IND application during 2011 to enable the start of clinical trials.
The 5T4 antigen is also the target of BioMedica’s own Phase II-stage therapeutic cancer vaccine TroVax®. The candidate is based on an attenuated modified vaccinia virus Ankara (MVA), engineered to deliver the 5T4 antigen.
TroVax is currently being tested against hormone-refractory prostate cancer (HRPC). The randomized, open-label U.S. Phase II study is assessing TroVax in combination with docetaxel compared with therapy using docetaxel alone. A Phase I/II trial evaluating TroVax in combination with first-line chemotherapy against mesothelioma is also expected to start during 2011, together with a trial in ovarian cancer patients.
A previous Phase III Trist study evaluating TroVax in metastatic renal cancer failed to meet its primary endpoint of improved survival compared with placebo. However, BioMedica stresses, analyses of the trial data have identified subgroups of patients for whom TroVax may be of significant benefit. Patients with a good prognosis who received TroVax plus interleukin-2 showed a significant survival advantage in comparison with good prognosis patients who received placebo plus IL-2. Moreover, survival was prolonged in patients who had normal hematology prior to receiving TroVax.
Last month BioMedica announced publication of the previously reported Trist trial data in Cancer Immunology, Immunotherapy. At the time the firm confirmed that data from the Trist study had enabled the development of an algorithm, termed the Immune Response Surrogate (IRS), for predicting which patients are most likely to mount a high 5T4 antibody response after therapy with TroVax.
The IRS is a combination of three baseline blood parameters, 5T4 antibody levels, hemoglobin, and haematocrit, which can be measured by a single blood test. The firm says when applied to data from previous clinical trials including Trist, the IRS showed a significant correlation between 5T4 antibody response induced in patients by vaccination with TroVax and survival.
The IRS is as a result being used in all TroVax trials including the current Phase II study in hormone refractory prostate cancer in addition to the planned sponsored Phase II studies in mesothelioma, colorectal, and ovarian cancers expected to start this year.
“The IRS will allow us to target a more responsive patient population, and we are confident that this novel biomarker will be further validated by results from our current Phase II clinical development program for TroVax,” comments Stuart Naylor, BioMedica CSO.