Phase 3 trial initiated for Ifinatamab Deruxtecan in Pretreated Metastatic Castration-Resistant Prostate Cancer: Merck, Daiichi Sankyo

Ifinatamab deruxtecan is a specifically engineered, potential first-in-class B7-H3 directed DXd antibody drug conjugate (ADC) discovered by Daiichi Sankyo and being jointly developed by Daiichi Sankyo and Merck, known as MSD outside of the United States and Canada.

Prostate cancer is the second most common cancer in men, and the fifth leading cause of cancer death in men worldwide. Nearly 1.5 million prostate cancer cases were diagnosed in 2022, with approximately 400,000 deaths globally.

While localized prostate cancer has a five-year survival rate of more than 90%, survival decreases to 31% in the advanced or metastatic stage. Approximately 10% to 20% of early-stage prostate cancer cases progress to metastatic disease within five years of treatment on hormonal therapies such as androgen deprivation therapy. Current standard of care for patients with mCRPC includes treatment with androgen receptor pathway inhibitors followed by taxane-based chemotherapy. However, due to poor prognosis associated with previously treated mCRPC, many patients do not receive subsequent therapy, reinforcing the need for new approaches to improve outcomes.

The current standard of care for patients with mCRPC includes treatment with androgen receptor pathway inhibitors followed by taxane-based chemotherapy. However, due to poor prognosis associated with previously treated mCRPC, many patients do not receive subsequent therapy, reinforcing the need for new approaches to improve outcomes.

“Despite the emergence of new therapies, the current treatment landscape for patients with metastatic castration-resistant prostate cancer is challenging, and there is a need for new treatments,” said Mark Rutstein, MD, Head, Therapeutic Area Oncology Development, Daiichi Sankyo. “Following the promising results seen in our earlier phase trial, IDeate-Prostate01 has been initiated to evaluate whether ifinatamab deruxtecan may replace standard taxane-based chemotherapy as a potential treatment strategy in patients with metastatic castration-resistant prostate cancer with disease progression during or after treatment with androgen receptor pathway inhibitors.”

“IDeate-Prostate01 marks the initiation of the third pivotal trial in the ifinatamab deruxtecan development program and reinforces our commitment to addressing critical unmet needs for patients,” said Marjorie Green, MD, Senior Vice President and Head of Oncology, Global Clinical Development, Merck Research Laboratories. “Our continued progress in the exploration of this potential first-in-class B7-H3 antibody drug conjugate in collaboration with Daiichi Sankyo, speaks to our pursuit of novel science in the hopes of making a difference for patients in need of new options.”

The initiation of IDeate-Prostate01 is based on results from the IDeate-PanTumor01 phase 1/2 trial previously presented at the 2022 and 2023 European Society of Medical Oncology (ESMO) Congresses where ifinatamab deruxtecan showed promising responses in heavily pretreated patients with mCRPC.

IDeate-Prostate01 is a multicenter, open-label, randomized phase 3 trial evaluating the safety and efficacy of ifinatamab deruxtecan (12 mg/kg) versus docetaxel (75 mg/m2) plus corticosteroid in patients with mCRPC. Eligible patients must have received prior treatment with one or two androgen receptor pathway inhibitors and experienced disease progression during or after at least eight weeks of treatment.

The dual primary endpoints of IDeate-Prostate01 are overall survival and radiographic progression-free survival. Secondary endpoints include objective response rate, time to first subsequent therapy, duration of response, time to pain progression, time to prostate-specific antigen (PSA) progression, PSA response, time to first symptomatic skeletal-related event and safety.

IDeate-Prostate01 will enroll approximately 1,440 patients across Asia, Europe, North America and Oceania.