Another phenylketonuria hold, courtesy of Homology

The phenylketonuria pipeline already had one project on clinical hold, and now it has another: Homology Medicines’ HMI-102 on Friday joined Biomarin’s BMN 307 in attracting scrutiny from the FDA. It is not yet clear exactly what the problem is with HMI-102, but Homology cited “elevated liver function tests” in the phase 1/2 Phenix trial. Stifel analysts suggested that Homology might have seen abnormally high or non-transient liver enzyme elevations, or that steroids could have failed to lower these enzymes. The news came a day after Biomarin said the clinical hold of BMN 307 would drag on a while longer: the FDA has requested more preclinical data, which is expected to take several quarters. That group needs to assuage concerns about cancer risks with its project after tumours were seen in mouse studies. Since Evaluate Vantage last looked at the PKU pipeline PTC Therapeutics’ PTC923 has moved into phase 3. This has a similar mechanism to Biomarin’s approved therapy Kuvan, which is only suitable for a fraction of patients; still, PTC says PTC923 could be used in a broader population. Homology, which fell 37% after hours, also recently took a gene editing asset, HMI-103, into the clinic.