The patent at issue in T 1259/22, whilst expiring in August 2024 with SPCs, highlights some of the major challenges for IP strategy in cell therapy
Background
The invention in the present case (EP2371361) was directed to a multi-step method to mobilise progenitor/stem cells (PSCs) in subjects by administering plerixafor (Mozobil®). Plerixafor is already known for the treatment of HIV. In this case, Plerixafor was used as an immunostimulant to mobilise hematopoietic stem cells in cancer patients into the bloodstream, so that they can be easily harvested.
The case discussed the applicability of Article 53(c) EPC, which excludes the patentability of methods of treatment or surgery of the human body. However, it is still possible to patent substances or compositions for use in such methods. The method in the patent was directed to a new use of plerixafor, in particular, its use in stem cell therapy.
Claim 1, in dispute, was directed to plerixafor for use in a method comprising:
- administering plerixafor to a subject to mobilise stem cells in said subject,
- harvesting said stem cells, and
- using the harvested stem cells in cell transplantation.
The patent was opposed, but was maintained by the opposition division, to which both the proprietor and opponents appealed.
The Board of Appeal decided whether the claimed method (as mentioned above) could be considered as a second medical use (or purpose-limited product claim) of plerixafor. The Board considered that in order for such a claim to qualify as a purpose-limited product claim,
“the claimed substance or composition must have a treatment-related link to a medical step of the multi-step method“.
Accordingly, each step of the method was considered separately to determine whether it was a medical step and, if so, whether the claimed compound (plerixafor) had activity in relation to surgery or therapy in this step, and it was noted that:
Step i): The technical effect of step i) was the mobilisation of the donor’s PSCs, i.e., the movement of the PSCs from the donor’s bone marrow to the donor’s peripheral blood.
The patentee asserted that the mobilisation of the donor’s PSCs from the donor’s bone marrow to the donor’s peripheral blood enhanced wound healing, restored organ tissue, regenerated myocardium, and increased the level of circulating blood cells, giving rise to an improved ability to fight infection and increased oxygen transport.
Moreover, it was argued that administering plerixafor prior to harvesting reduced the number of harvest procedures required and thereby reduced the severe side effects caused by harvesting. These effects were claimed to be therapeutic effects experienced by all subjects.
However, the Board noted that the PSCs mobilised in step i) remain within the donor’s body for less than two days before being harvested and are not returned to it afterwards. The board did not find it credible that the PSC donor treated in step i) will benefit from any of the effects listed by the proprietor. The Board therefore concluded that step i) of claim 1 did not define a method for treatment by therapy.
Step ii): The technical effect of step ii) was the removal of the PSCs mobilised in step i) from the donor’s peripheral blood. It was not disputed that this was a surgical step. However, according to the Board, the reduction in side effects and complications was independent of the surgical step and plerixafor played no role in this. It was noted that step ii) was carried out on healthy PSC donors, who are not in need of this or any other type of PSC harvesting procedure to restore their health. The board therefore concluded that there is no treatment-related link between plerixafor and step ii).
Step iii) gave rise to a therapeutic effect in the recipient of the PSC transplant. Step iii) therefore additionally defined a method for treatment by therapy. This was not disputed. However, the therapeutic effect in step iii) was found to occur from the donor’s PSCs collected in step ii), and not from plerixafor. It was found that there is no treatment-related link between plerixafor, and the therapeutic effect achieved in step iii) via plerixafor’s PSC mobilisation activity in step i). In fact, these two technical effects occurred in distinct, non-overlapping groups of subjects, i.e., healthy PSC donors versus patients in need of a PSC transplant.
In view of these considerations, it was concluded that claim 1 was not a purpose-limited product claim under Article 54(5) EPC. Given the fact that plerixafor was already known, the claim was found to lack novelty and the patent was revoked.
Conclusion
This case is noteworthy in relation to medical use claims. The product plerixafor may have been beneficial in improving harvesting of specific cells from healthy subjects, but it was not as such linked with any therapeutic effect. Thus, it can be inferred that not all medical use claims can be patentable, even though there may be a therapeutic angle to them. What is important to note and demonstrate is that the compound must be directly linked with the claimed therapeutic effect.