Please assess the completion status of the following clinical trial:

Trial Title: Metformin Plus Paclitaxel for Metastatic or Recurrent Head and Neck Cancer

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE2
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* 18 years or older~* Biopsy-proven head and neck squamous cell carcinoma~* Ineligibility for curative intent therapy, e.g., surgery or radiation therapy~* recurrent or stage IV disease~* previous failure to platinum-based chemotherapy~* measurable disease according to RECIST v1.1~* PS ECOG 0-2~Exclusion Criteria:~* known hypersensitivity to metformin or paclitaxel~* SNC metastasis~* Acute or chronic infection

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

Study Arms:
- Paclitaxel, placebo (Type: ACTIVE_COMPARATOR): Paclitaxel 175mg/m² q21d until disease progression, unacceptable toxicity or consent withdrawal
- Paclitaxel plus metformin (Type: EXPERIMENTAL): Paclitaxel 175mg/m² q21d + metformin up to 2500mg/d until disease progression, prohibitive toxicity or consent withdrawal

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