OncoSec’s defense of weak preliminary Tavo data for PD-1 resistant melanoma can’t stop a rout

OncoSec execs may be regretting their decision to release preliminary Phase IIb data on the combination of Merck’s Keytruda and their big pipeline play Tavo. 

Researchers are reporting results for only 9 patients with metastatic melanoma at 12 weeks, and came out in a defensive posture for the 2 partial responses they tracked at that stage in KEYNOTE-695. All of the patients had seen their cancer progress after treatment with Opdivo or Keytruda in the lead study at OncoSec.

Despite its defense, and a chance to wait for 24-week data on more patients, investors bailed in an ugly rout that sent the biotech’s shares $ONCS down 57% in pre-market trading. The setback for what has been intended to be a registration study pushed shares into penny stock terrain.

OncoSec is taking a popular route in the oncology field, looking to spur an immune response among patients who aren’t durably helped by the PD-1/L1 crowd of checkpoint inhibitors. Only about 1 in 5 of those patients see a big impact from therapy, leaving a big market to address by the next-gen combo crowd.

OncoSec, though, only managed to raise doubts about its approach, though the game is far from over. A total of 21 patients have been recruited for the study.

OncoSec and Merck hammered out their collaboration on this in 2017, then followed up last spring with an agreement to expand into breast cancer.

Adil Daud

“There is currently no approved therapy for the KEYNOTE-695 patient population. A 10% response rate is considered meaningful in this cohort, since this is about what we expect with additional chemotherapy, however, such responses lack durability. The preliminary tumor responses (22% BORR and 33% DCR) and supporting immune data observed here for the first time are important,” said Adil Daud, a professor at the UCSF Helen Diller Family Comprehensive Cancer Center.

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VP Oncology Biology
Skyhawk Therapeutics Waltham, MA
Associate Director CMC
Elektroki Boston, MA
Director Process Development
Elektroki Boston, MA
Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT

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