An article in the Grauniad today reports a letter written by The Coalition for Affordable T-DM1 to the Health Secretary Jeremy Hunt.
The letter asks Mr Hunt to "authorise the domestic manufacture and/or importation, use and sale of biosimilar versions
of trastuzumab emtansine (TDM1) used in the treatment of breast cancer, to be supplied to
the government for use and sale in the UK", which they argue can be done under the Crown Use provisions of the UK Patents Act 1977 (sections 55 to 59). This is apparently necessary because the medicine is very expensive and unaffordable to patients in the UK, costing in the region of £100k for a year's treatment.
The letter does not indicate what patent would need to be authorised for use, which seems to me a bit strange. I have, however, found one that seems to fit the bill: EP1689846B1, which was granted in March 2013 to ImmunoGen, Inc., claiming a cell-binding agent maytansinoid conjugate with the formula shown above, where Ab is trastuzumab.
T-DM1, more commonly known by its trade name Kadcyla, is an antibody-drug conjugate, being a combination of the monoclonal antibody trastuzumab (trade name Herceptin) with a cytotoxic agent DM1, a maytansinoid. The drug can apparently be of some use in treating HER2-positive metastatic breast cancer, although is not a cure and results show that it might be able to extend life by typically a few months. The National Institute for Health and Care Excellence (NICE) have indicated that the drug is not worth funding, finding last year that it is not recommended for treatment because it was not a cost-effective use of NHS resources.
To my knowledge, the Crown Use provisions in the UK Patents Act 1977* have never been applied to the provision of drugs (although I would be happy for someone to prove me wrong). It would be interesting to see whether this case will establish a precedent, but I strongly suspect that it will not.
*As pointed out in the comments below, Crown Use provisions in the 1949 Act were used. However, apart from the case of Henry Brothers v MOD  RPC 693, which was not about drugs, I am not aware of any cases under the 1977 act relating to sections 55 to 59 and do not know of any patents that have been the subject of an order under section 55. Making an order in this case would therefore seem to be setting a precedent, which I suspect the current government would be very unwilling to do.