Please assess the completion status of the following clinical trial:

Trial Title: Palbociclib in Estrogen Receptor Positive (ER+) Human Epidermal Growth Factor Receptor 2 Positive (HER2+) Metastatic Breast Cancer

Study Design Characteristics:
- Allocation: NON_RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: NONE
- Phase: PHASE1/PHASE2
- Number of Arms: 4.0

Eligibility Criteria:
Inclusion Criteria:~* Pathologically confirmed diagnosis of Estrogen Receptor (ER) positive and HER2 (human epidermal growth factor receptor 2) positive metastatic breast cancer based on local laboratory results.~* Prior treatment with a taxane (including paclitaxel, docetaxel and/or nanoparticle protein-bound paclitaxel).~* Prior treatment with trastuzumab with or without pertuzumab.~* Measurable or non-measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) criteria version 1.1.~* Eastern Cooperative Oncology Group Performance Status of 0-2~* Adequate organ and marrow function~* Women must be post-menopausal~* Must be able to swallow pills~Exclusion Criteria:~* Current or anticipated use of other investigational agents~* Prior therapy with a cyclin-dependent kinase 4/6 inhibitor~* Subject has received chemotherapy or radiotherapy within 14 days prior to Cycle 1, Day 1 of the study or has not recovered from adverse events due to agents administered more than 14 days earlier~* Subject has leptomeningeal disease~* History of allergic reactions attributed to compounds of similar chemical or biologic composition to palbociclib or other agents used in study~* Subject has other illness or disease that the investigator believes will interfere with study requirements.

- Gender: FEMALE
- Minimum Age: 18 Years
- Maximum Age: None
- Healthy Volunteers: f

Study Arms:
- Phase 1: Palbociclib 75 mg (Type: EXPERIMENTAL): Palbociclib 75 milligrams (mg) by mouth (PO) daily Letrozole 2.5 mg PO Daily Ado-trastuzumab Emtansine (T-DM1) 3.6 milligrams per kilograms (mg/kg) intravenous (IV) Day 1
- Phase 1: Palbociclib 100 mg (Type: EXPERIMENTAL): Palbociclib 100 milligrams (mg) by mouth (PO) daily Letrozole 2.5 mg PO Daily Ado-trastuzumab Emtansine (T-DM1) 3.6 milligrams per kilograms (mg/kg) intravenous (IV) Day 1
- Phase 1: Palbociclib 125 mg (Type: EXPERIMENTAL): Palbociclib 125 milligrams (mg) by mouth (PO) daily Letrozole 2.5 mg PO Daily Ado-trastuzumab Emtansine (T-DM1) 3.6 milligrams per kilograms (mg/kg) intravenous (IV) Day 1
- Phase 2: RP2D (Type: EXPERIMENTAL): Recommended Phase 2 dose (RP2D; determined during Phase 1 Safety Run In) Palbociclib by mouth (PO) daily Letrozole 2.5 mg PO Daily Ado-trastuzumab Emtansine (T-DM1) 3.6 milligrams per kilograms (mg/kg) intravenous (IV) Day 1

Based on this trial design, predict the completion outcome and termination type (if applicable).