Investors have driven down shares in Halozyme Therapeutics following news investigators halted a phase 1b/2 pancreatic cancer trial for futility. The failure of the investigator-initiated trial to show signs of efficacy raised doubts about the ability of PEGPH20 to deliver positive data in phase 3, despite differences in the designs of the studies.
SWOG, the researcher network formerly known as Southwest Oncology Group, told Halozyme the independent data monitoring committee had recommended halting enrollment in the phase 1b/2 after getting a look at preliminary data. Those interim results showed adding PEGPH20—an asset based on a recombinant human hyaluronidase enzyme—to a modified FOLFIRINOX chemotherapy regimen was unlikely to improve overall survival.
With Halozyme swinging for phase 3 success in pancreatic cancer on the back of phase 2 results that failed to wow, the readthrough from the setback in the SWOG study to the biotech’s key trial panicked investors. Shares in Halozyme closed down almost 9% following the SWOG news.
However, while PEGPH20 may ultimately fail in phase 3—as other pancreatic cancer candidates have done—there is a question over whether this outcome is made significantly more likely by the phase 1b/2 halt.
Halozyme is developing PEGPH20 for use in patients who are determined to be hyaluronan-high. Hyaluronan is a chain of sugars found on the periphery of some tumors. Halozyme thinks wiping out hyaluronan will change the tumor microenvironment and, in doing so, allow chemotherapies to hit the cancer harder. As the presence of hyaluronan is critical to the success of this approach, Halozyme is limiting enrollment in the phase 3 to people with high levels of the glycosaminoglycan.
The phase 3 is using tumor biopsies to assess levels of hyaluronan. And Halozyme has a companion diagnostic pact with Roche’s Ventana to create a test so physicians can identify patients who are more likely to respond to PEGPH20.
In contrast, the enrollment criteria for the SWOG trial make no mention of hyaluronan status. As Halozyme trials to date suggest around 40% of pancreatic cancer patients have elevated levels of hyaluronan, it is likely many subjects in the SWOG clinical trial lacked large amounts of the glycosaminoglycan.