When Pfizer laid out the ambitious vision for its new oncology division in February, it announced that it was taking the antibody-drug conjugate sigvotatug vedotin directly from Phase 1 to Phase 3. Now the drugmaker is releasing the updated data that convinced it to accelerate the drug acquired from its $43 billion deal for Seagen last year.
In updated results released Thursday, Pfizer said that about one-fifth of lung cancer patients who received sigvotatug vedotin saw their tumors shrink by at least 30%. And in 40 patients with non-squamous, non-small cell lung cancer, which includes forms of lung cancer that typically start from the periphery of the lungs, 13 patients saw their tumors shrink by at least that amount, a 32.5% response rate.
The data from the 306-patient study, which also looked at other solid tumors, were shared in an abstract published ahead of the American Society of Clinical Oncology meeting next week.
Antibody drug conjugates, or ADCs, feature a toxin attached to an antibody that hones in on tumor cells to kill them. Sigvotatug vedotin targets integrin B6, which is highly expressed in non-small cell lung cancer, as well as other tumors.
Megan O’Meara“We’ve been really interested in targeting integrins because they are expressed on a lot of different types of tumors, but they’re very difficult to target because a lot of the different integrins look similar,” said Megan O’Meara, Pfizer Oncology’s head of early-stage development. “Many of the other companies have created antibodies against integrins, but there’s a lot of nonspecific binding, so then that leads to toxicity for patients.”
Roughly a third of lung cancer patients in the study reported serious adverse events, and 13.3% had adverse events that led them to discontinue treatment.
The most common grade 3 or higher adverse events in the Phase 1 study were shortness of breath (about 10% of patients), fatigue, and low counts of a type of white blood cell called neutrophils (about 5% of patients). One patient died from pneumonitis related to treatment.
Pfizer started the Phase 3 study in February, giving sigvotatug vedotin in second- and third-line non-squamous, non-small cell lung cancer. The trial aims to enroll 600 participants who have been treated with chemotherapy, as well as potentially an immune-checkpoint inhibitor or a targeted therapy for a specific cancer mutation. Patients in that study will receive a 1.8 mg/kg dose of sigvotatug vedotin twice every four weeks or docetaxel chemotherapy in the control arm.
Earlier results from the study were shared in a poster last year at ASCO and at Pfizer’s oncology day in February.