A Clinical Study of Patritumab Deruxtecan to Treat Breast Cancer (MK-1022-016)

Launched by MERCK SHARP & DOHME LLC · Jul 2, 2025

Keywords

ClinConnect Summary

This clinical trial is studying a new treatment called patritumab deruxtecan for a specific type of breast cancer that is hormone receptor-positive (meaning the cancer grows in response to hormones like estrogen) and HER2-negative (meaning it has low levels of a certain protein called HER2). This type of breast cancer can be advanced and either can’t be removed completely by surgery or has spread to other parts of the body. The study aims to find out if this new treatment helps people live longer or keeps the cancer from growing or spreading better than current treatments like chemotherapy or another drug called trastuzumab deruxtecan.

People who might be eligible for this study are adults who have this particular type of breast cancer that has progressed despite previous hormone-based treatments combined with certain targeted drugs called CDK4/6 inhibitors. They must have measurable cancer and be in generally good health with controlled HIV if applicable. Participants should not have other serious health issues, prior chemotherapy for advanced disease, or certain lung or eye problems. If you join the study, you can expect to receive either the new drug or one of the current treatments, and the doctors will closely monitor your health and how well the treatment is working. This study is not yet recruiting, but it is open to all genders within the eligible age range.

Gender

ALL

Eligibility criteria

• Inclusion Criteria:
• The main inclusion criteria include but are not limited to the following:
• • Has a diagnosis of hormone receptor positive (HR+)/human epidermal growth factor receptor 2 (HER2)- invasive breast carcinoma that is either locally advanced disease not amenable to resection with curative intent (herein called unresectable) or metastatic disease not treatable with curative intent
• • Has centrally-confirmed HR+ and HER2- results and human epidermal growth factor receptor 3 (HER3) evaluable results from a biopsy obtained from a distant metastatic site on or after the most recent line of therapy (with certain exceptions)
• * Must have had progression or recurrence on prior cyclin-dependent kinase (CDK)4/6 inhibitor + endocrine therapy (ET) with one of the following:
• • Radiographic disease progression, as assessed by the investigator, on CDK4/6 inhibitor + ET as 1L for treatment of unresectable locally advanced or metastatic HR+/HER2- breast cancer. CDK4/6 inhibitor + ET must be the only line of therapy received in the advanced setting, or
• • Disease recurrence, either radiographic and/or confirmed histologically via biopsy as assessed by the investigator, while on adjuvant ET in combination with a CDK4/6 inhibitor OR within 24 months from the date of last dose of adjuvant CDK4/6 inhibitor
• • Measurable disease per RECIST 1.1 as assessed by the local site investigator/radiology
• • Human immunodeficiency virus (HIV)-infected participants must have well controlled HIV on antiretroviral therapy (ART)
• • An ECOG performance status of 0 or 1 assessed within 7 days before randomization
• Exclusion Criteria:
• The main exclusion criteria include but are not limited to the following:
• • Has breast cancer amenable to treatment with curative intent
• • Is eligible to receive additional endocrine-based treatment in the advanced setting as determined by the investigator
• • Has a known germline breast cancer gene (BRCA) mutation (deleterious or suspected deleterious) where poly (ADP-ribose) polymerase (PARP) inhibitor(s) is a potential treatment option
• • Has current visceral crisis or is at risk for impending visceral crisis that has or may cause imminent organ compromise and/or other life-threatening complications
• * Has any of the following:
• • A pulse oximeter reading \<92% at rest, OR
• • Requires intermittent supplemental oxygen, OR
• • Requires chronic supplemental oxygen
• • Has uncontrolled, significant cardiovascular disease or cerebrovascular disease
• • Has ≥Grade 2 peripheral neuropathy.
• • Has clinically significant corneal disease
• • Has received prior chemotherapy for unresectable locally advanced or metastatic breast cancer (mBC)
• • Has received prior treatment with an anti-HER3 antibody and/or antibody-drug conjugate (ADC) that consists of a topoisomerase I inhibitor (eg, T-DXd) or any other topoisomerase I inhibitor therapy
• • Has received prior systemic anticancer therapy within 4 weeks (or 5 half-lives, whichever is shorter) before randomization
• • Note: Participants previously treated with ET plus a CDK4/6 inhibitor) may participate as long as at least 2 weeks have elapsed since the last dose of therapy was administered
• • Has received prior radiotherapy for non-CNS disease, or required corticosteroids for radiation-related toxicities, within 14 days of the first dose of study intervention
• • Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
• • Known additional malignancy that is progressing or has required active treatment within the past 3 years
• • History of (noninfectious) pneumonitis/interstitial lung disease (ILD) that required steroids, has current pneumonitis/interstitial lung disease, or has suspected ILD/pneumonitis that cannot be ruled out by imaging at Screening
• • Severe hypersensitivity (≥Grade 3) to HER3-DXd and/or any of its excipients
• • Severe hypersensitivity (≥Grade 3) to all the available TPC and/or any of their excipients