Neoplasms

Symptoms and General Pathology

All Conditions

Skin and Connective Tissue Diseases

Neoplasm Metastasis

Breast Neoplasms

Breast Diseases

Skin Diseases

Antineoplastic Agents

All Drugs and Chemicals

Trastuzumab

Antineoplastic Agents, Immunological

trastuzumab 4 mg/kg and monalizumab 750 mg every two weeks.

Monalizumab

Marleen Kok, MD

In this phase II clinical trial the efficacy of the combination of monalizumab and trastuzumab is assessed in patients with metastatic or locally incurable HER2-positive breast cancer

In this phase II clinical trial with an explorative nature, the efficacy of the combination of monalizumab and trastuzumab is assessed in patients with metastatic or locally incurable HER2-positive breast cancer. Clinical efficacy will be assessed in patients with high stromal tumor-infiltrating lymphocytes (sTILs) or low sTILs in two separate cohorts (higher or equal to 5% versus lower than 5%). Since the combination of monalizumab and trastuzumab has not been administered before, dose limiting toxicities (DLTs) will be monitored throughout the trial using the Pocock-type boundary rules for continuous monitoring of toxicity in phase II trials.

In the first stage, 11 patients will be accrued per cohort. If there are 1 or fewer responses in these 11 patients, the study will be stopped. Otherwise, 8 additional patients will be accrued for a total of 19 patients.

The study will start with two cohorts (sTILs high and sTILs low), a total of 22 (2x11) patients will be included in the first stage. Dependent on the interim analysis (continuation of no cohorts, 1 or 2 cohorts), a maximum of 38 patients will be included.

Two cohorts; high TILs (≥ 5%) and low (\< 5%) TILs

Monalizumab and Trastuzumab In Metastatic HER2-pOSitive breAst Cancer: MIMOSA-trial

number of patients with partial response or complete response according to RECIST1.1

number of patients with complete response, partial response or stable disease for more than 24 weeks according to RECIST1.1

From date of registration until date of first documented progression or date of death, which ever comes first

From date of registration until date of death

Adverse events will be graded according to NCI Common Toxicity Criteria version 5.0

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization
Monalizumab and Trastuzumab In Metastatic HER2-pOSitive breAst Cancer: MIMOSA-trial	NCT04307329	Breast Cancer	Monalizumab Trastuzumab	18 Years -	The Netherlands Cancer Institute
Monalizumab and Trastuzumab In Metastatic HER2-pOSitive breAst Cancer: MIMOSA-trial	NCT04307329	Breast Cancer	Monalizumab Trastuzumab	18 Years -	The Netherlands Cancer Institute
Monalizumab and Trastuzumab In Metastatic HER2-pOSitive breAst Cancer: MIMOSA-trial	NCT04307329	Breast Cancer	Monalizumab Trastuzumab	18 Years -	The Netherlands Cancer Institute

Spots Global Cancer Trial Database for accessible lesion for study biopsies