At an MS Masters Forum in Rome yesterday I was teaching MSologists and MS clinical nurse specialists using a recently created board game, which I like to think of as being MS Monopoly. MS monopoly is based on a game of chance that lets you discuss case scenarios and make treatment choices. Then you roll a dice, which determines the outcome of your choice.
Two things emerge from playing the game. Firstly, how choosing an immune reconstitution (IRT) addresses so many of the treatment aims and longterm issues of safety. The question I ask is why aren’t the IRTs dominating the treatment landscape?
Secondly, it became clear how many times natalizumab was considered as a treatment option and discarded because of its PML risk. From yesterday’s discussions it clear to me that natalizumab is the ‘time-to-think’ DMT, i.e. you start someone on natalizumab for 6-12 months whilst you make the necessary long-term decisions. This may be necessary to wait for lymphopaenia to recover, to complete a vaccination programme (e.g. the three-dose HPV polyvalent vaccine), to wait to get the all-clear on a previously-treated malignancy, to prevent rebound on stopping fingolimod so that the woman with MS can fall pregnant, or to complete a diagnostic work-up. The latter indication underpins our #AttackMS trial design.
Another indication for natalizumab is to prevent CNS adverse events associated with cancer immunotherapy. I recently recommended that a patient with MS who had disseminated bowel cancer and was about to start an immune checkpoint inhibitor go onto natalizumab despite being JCV positive to prevent exacerbation of her MS. The rationale being that the polyclonal activation of her T-cells in the periphery, including her autoimmune cells responsible for her MS, would not traffic to the brain and spinal cord and cause an MS relapse. The downside of this strategy is that if she had occult secondaries in her CNS then natalizumab will prevent her T-cells finding and clearing these cells. As bowel cancer rarely metastasizes to the CNS we thought this was a risk worth taking. Last I heard she was doing well from the MS perspective, but not that well in relation to her bowel cancer.
I am sure natalizumab will prevent the CNS complications associated with CAR-T cell therapies. Could this be a repurposing opportunity for natalizumab?
What makes natalizumab so uniquely special as a DMT are the observations that it has the most rapid onset of action of all the DMTs, it has very high efficacy, its mode of action can be reversed with plasma exchange and natalizumab does not cause systemic immunosuppression. The only downside of natalizumab therapy is the long-term PML and other CNS infection risk and the emerging CNS lymphoma risk. These are all due to reduced CNS immune surveillance. The fact that extended interval dosing (EID) reduces the PML risk by over 80% suggests natalizumab may make a resurgence and all these CNS side effects may be preventable. However, for this to happen we need to be able to prescribe natalizumab more liberally as a first-line treatment for active MS. If anyone from Biogen is reading this blog post can you please ask the powers that be in Biogen to consider asking the EMA to reconsider natalizumab’s label? By not doing this you are denying many pwMS access to natalizumab, albeit for a short period of time as highlighted above.
The good news is that the EMA has accepted the EID data and it is now in natalizumab’s summary of product characteristics.
New text in the EMA’s SmPC: In a pre-specified, retrospective analysis of US anti-JCV antibody-positive natalizumab patients (TOUCH registry), the risk of PML was compared between patients treated with the approved dosing interval and patients treated with extended interval dosing as identified in the last 18 months of exposure (EID, average dosing intervals of approximately 6 weeks). The majority (85%) of patients dosed with EID had received the approved dosing for ≥1 year prior to switching to EID. The interim analysis showed a lower risk of PML in patients treated with EID (hazard ratio = 0.06 95% CI of hazard ratio = 0.01- 0.22). The efficacy of natalizumab, when administered with EID, has not been established, and therefore the benefit/risk balance of EID is unknown (see section 4.4).
For those interested, I have included the latest PML figures from Biogen.