XENOVA AND QLT DISCONTINUE TARIQUIDAR PHASE III NSCLC TRIALS

    Xenova and QLT will continue to explore the potential of tariquidar and
          carefully review the data in order to plan future development

Slough, UK, 13 May, 2003 - Xenova Group plc (NASDAQ NM: XNVA; London Stock
Exchange: XEN) today announces that QLT Inc, (NASDAQ: QLTI; TSX: QLT) will stop
the current Phase III trials of tariquidar as an adjunctive treatment for
patients with non-small-cell-lung cancer (NSCLC). This decision follows a
recommendation by the Independent Data Safety Monitoring Committee (DSMC), which
completed the un-blinded interim review of the data for the two ongoing trials
in this indication. The Phase IIb trial for tariquidar in chemorefractory breast
cancer underway at MD Anderson, Texas is unaffected by this decision and this
trial continues.

Members of QLT's clinical development team will now be un-blinded so that they
have an opportunity to review all of the data and make informed decisions about
plans for the future development of tariquidar. Data from the 304 patients
already enrolled in this study represent the largest collection of efficacy and
safety data from a randomized, placebo-controlled study of a third generation
P-gp inhibitor and will offer valuable insight into the potential for tariquidar
in this or other indications. It is QLT's intention to exploit the value of this
database and make planning decisions for tariquidar after a thorough analysis of
such data.

David Oxlade, Chief Executive Officer of Xenova, said:

'Xenova continues to believe that tariquidar has potential as an MDR modulator
in cancer. We will explore further development opportunities once the un-blinded
data from these NSCLC studies have been assessed. The Phase IIb trial at MD
Anderson, in chemorefractory breast cancer continues.'

'Xenova has decided to take immediate steps to substantially reduce operating
costs. This will include a reduction in headcount as well as further programme
prioritisation. Going forward, Xenova will focus on its key clinical development
programmes.'

Conference Call Information

Xenova will hold a conference call on Tuesday, 13 May at 08:30 a.m. BST. For
details contact Claire Rowell at Financial Dynamics, telephone +44 (0) 20 7269
7285.