The market yanked the rug out from under Bicycle Therapeutics (BCYC -2.52%) this morning in response to disappointing clinical trial results. Investors concerned about the company's experimental cancer treatments pushed the stock 29% lower as of 10:36 a.m. ET on Monday.
Bicycle Therapeutics is a pre-commercial biotech advancing an all-new way to treat cancer. The company could be the first to market with bicyclic peptides, which can carry a chemotherapy agent to cells that express signs of tumor growth.
Today, the market is reacting to data from the phase 1 portion of a two-part trial with a nectin-4 directed bicycle called BT8009 in advanced-stage bladder cancer patients. Once one side of BT8009 enters nectin-4 positive cells, it releases a chemotherapy agent called monomethyl auristatin E (MMAE).
In terms of efficacy, Bicycle's candidate hit impressive marks. Treatment with BT8009 shrank tumors for four of the first 12 evaluable patients, and one achieved complete remission.
The stock is tanking today because BT8009's safety profile doesn't look much better than the established therapy it could end up competing with. In 2019, Seagen (SGEN -0.30%) launched Padcev, which uses the same chemotherapy agent tied to a great big antibody that also targets nectin-4.
It's hard to make cross-trial comparisons, but it looks like treatment with BT8009 leads to more free-floating MMAE in the bloodstream than Padcev, a fact which presents the safety risk. Across all three doses tested, 14% of patients treated had severely low white blood cell counts.
It's probably a good idea to wait for more data before turning your back on BT8009 and Bicycle Therapeutics. That said, trying to catch this falling knife right now probably isn't worth the risk.