Amid string of splashy pandemic IPOs, ADC returns for its millions
Six months after withdrawing their bid for a massive IPO, ADC Therapeutics is back with a more conservative number: $100 million.
The Swiss biotech had swung from huge funding round to huge funding round before, with its lead program nearing a regulatory submission. It filed for a $200 million IPO in September. They evidently found few takers, though, as they withdrew the bid within two weeks of pricing.
Now, though, the global pandemic has drained money out of much of the stock market and funneled it into drugmakers. Biotech IPO after biotech IPO has landed with a splash. Zentalis, a small and obscure cancer biotech that privately raised a small fraction of what ADC has raised, managed a surprising $165 million to open the month. ORIC Therapeutics filed for a $75 million offering and emerged less than a week later with $120 million.
That should make it a ripe market for ADC, a company that, led by AstraZeneca veteran Chris Martin and Wyeth veteran Jay Feingold, already raised over $530 million on the private market since its 2011 founding and is closer to an FDA approval than any of the other pandemic era biotech IPOs. ADC has yet to price its new offering, but the September attempt would’ve valued the company at $1.8 billion.
ADC stands for antibody-drug conjugate, the old construct for building targeted cancer therapies that has gained steam again in recent years. The idea is to attach a cell-killing chemical — chemotherapy — into an antibody that guides the chemical directly to the tumor, as opposed to diffusing the chemical throughout the body like in traditional chemotherapy. Three such drugs have been approved in the last few years: two from Seattle Genetics and, last week, one from Immunomedics.
ADC’s platform tries to improve on the original principle by using a class of chemicals called pyrrolobenzodiazepines instead of traditional chemotherapy. Originally developed in Streptomyces bacteria, these chemicals bond to specific grooves of DNA inside the tumor, preventing the cancer cells from dividing and eventually killing them.
The company’s lead drug is ADCT-402, or loncastuximab tesirine, which they are testing in relapsed or refractory diffuse large B-cell lymphoma. An early 52-patient readout from their 145-patient pivotal trial in December showed a 46.2% response rate and a 19.2% complete response rate. They are aiming for a BLA submission by the third quarter of 2020.
The company has reported promising results on a second candidate, ADCT-301 or camidanlumab tesirine, in Hodgkin’s lymphoma, with a response rate of 86.5% at dosing in a Phase II trial of fifth-line patients. This month, though, the FDA placed a partial clinical hold on the trial after two patients were diagnosed with Guillain-Barré syndrome, a rapid muscle weakness caused by the immune system attacking its own tissue. A partial hold had been placed on a Phase I trial in 2017 for the same reason.
Social image: Chris Martin, ADC Therapeutics CEO via YouTube