Table 1.

Characteristics of the clinical trials (ClinicalTrials.gov)

Study	Type of study	Drug	Status	Patients, n	Population
PANACEA NCT02129556 [16]	Single-arm phase Ib/II study	Experimental: MK-3475 (pembrolizumab) with trastuzumab (single arm) Phase Ib: MK-3475 at a dose of 2 or 10 mg/kg (i.v.), or a fall-back dose of 1 mg/kg, together with trastuzumab at 6 mg/kg (i.v.) once every 3 weeks Phase II: MK-3475 at a flat dose of 200 mg (i.v.) together with trastuzumab at 6 mg/kg (i.v.) once every 3 weeks until progression, lack of tolerability, or 24 months of treatment A dose of 8 mg/kg trastuzumab will be used in cycle 1 if prior treatment with trastuzumab has been stopped more than 3 months prior	Recruitment completed	58	Metastatic Breast cancer, central nervous system after local treatment included
AVIATOR study NCT03414658	Randomized phase II open label trial	Trastuzumab and vinorelbine with avelumab or avelumab and utomilumab in advanced HER2+ breast cancer	Recruiting	Estimated 100	Patients with HER2-positive metastatic breast cancer who have progressed on prior trastuzumab and pertuzumab
NCT02649686 [21]	Randomized phase Ib/II study	Durvalumab plus trastuzumab Durvalumab q3w until PD trastuzumab q3w ×6	Active, not recruiting	15	HER2-positive metastatic breast cancer
NCT02403271	Phase Ib/II multicenter study	Ibrutinib in combination with durvalumab (MEDI4736) in subjects with relapsed or refractory solid tumors	Completed	124	Non-small cell lung cancer breast cancer Pancreatic cancer
NCT03032107	Phase Ib study	Pembrolizumab combined with trastuzumab emtansine	Recruiting	Estimated 27	Metastatic breast cancer
NCT03125928	Single-arm phase IIA open label study	Atezolizumab in combination with paclitaxel, trastuzumab, and pertuzumab	Recruiting	Estimated 50	HER2-positive metastatic breast cancer
NCT02605915	Nonrandomized phase Ib study	Atezolizumab in combination with trastuzumab emtansine or with trastuzumab and pertuzumab (with and without docetaxel) in patients with HER2-positive breast cancer and atezolizumab with doxorubicin and cyclophosphamide in HER2-negative breast cancer	Active, not recruiting	Estimated 98	Metastatic breast cancer
NCT03417544	Single-arm phase II study	Atezolizumab in combination with pertuzumab plus high-dose trastuzumab	Recruiting	Estimated 33	HER2-positive metastatic breast cancer Central nervous system metastases
NCT03595592	Randomized phase III interventional clinical trial	Atezolizumab, pertuzumab, and trastuzumab with chemotherapy as neoadjuvant treatment	Not yet recruiting	Estimated 650	Neoadjuvant HER2-positive early high-risk and locally advanced breast cancer (APTneo)
NCT02924883	Randomized, multicenter, double-blind, placebo-controlled phase II trial	Trastuzumab emtansine in combination with atezolizumab or atezolizumab-placebo	Active, not recruiting	Estimated 202	HER2-positive locally advanced or metastatic breast cancer who have received prior trastuzumab and taxane-based therapy
NCT03650348	Phase Ib open-label, dose escalation study	PRS-343 in combination with atezolizumab	Recruiting	Estimated 70	HER2-positive advanced or metastatic solid tumors Breast, gastric, bladder, and solid tumors
NCT03199885	Randomized, double-blind phase III trial	Paclitaxel/trastuzumab/pertuzumab with atezolizumab or placebo	Not yet recruiting	Estimated 600	First-line HER2-positive metastatic breast cancer
NCT03523572	Phase Ib, nonrandomized, dose escalation study	Trastuzumab deruxtecan with nivolumab	Recruiting	99	HER2-positive metastatic breast cancer, bladder cancer
NCT03726879	Randomized, double-blind phaseIII trial	Atezolizumab or placebo in combination with neoadjuvant doxorubicin + cyclophosphamide followed by paclitaxel + trastuzumab + pertuzumab	Recruiting	453	Early HER2-positive breast cancer