Sangamo reported data at the WORLD symposium yesterday. The stock dropped over 30% as the data looked underwhelming. (it was)
2 patients in the MPS II trial that were at the highest dose 5e13 both had issues.
One of the patients (patient 6) who was significantly overweight was likely given too much vector (since the therapy is dosed by weight) and developed transaminitis. Before the patient developed transaminitis the patients plasma levels of IDS were significantly higher and approaching normal levels.
The other patient (patient 5) was likely a non-responder to therapy.
3 other patients who have been dosed at the 5e13 dose level in the expansion cohort potentially can replicate the results of patient 6 without the SAE. This would be a significant achievement and should only take ~3 months from now to determine.
Adding confidence to the potential for a positive result at the next read out for this trial is the results from the 2 patients at the highest dose (5e13) in the MPS I trial. (same technology)
All patients are given steroids (oral prednisone) prior to dosing and then tapered over 20 weeks. (~140 days). Subject 2 and 3 therefore should see continued increase in IDUA activity over the next 3 months. Subject 3 already had a significant reduction in urinary GAGS at the 50 day mark and it will likely continue barring any unforeseen circumstances.
In addition, ZFN 2.0 which may increase IDS/IDUA production by 5-20x is already being manufactured. There is also the potential for clinical data from Sangamo's other clinical programs and a Tau/CNS partnership in the near term.
I sold the puts from the straddle I put in place before the results and continue to hold some shares. I will look to accumulate more shares after CTMX R&D day on February 26th.
Biotech investing is very risky and early stage results are often ambiguous. Sangamo proved that in-vivo gene editing works in humans. They just need to optimize the dosing/technology to reach proper therapeutic levels.