Trial results for the Phase 2 study (NCT02874430) investigating metformin hydrochloride and doxycycline in patients with localized breast or uterine cancer were posted on ClinicalTrials.gov on 2026-04-22. The study was terminated, with 0 participants achieving progression-free survival and 0 participants achieving overall survival.
Background
The Phase 2 trial (NCT02874430) investigated metformin hydrochloride and doxycycline for localized breast or uterine cancer. Metformin hydrochloride was hypothesized to stop the growth of cancer cells by blocking enzymes needed for cell growth. Doxycycline was thought to stop bacterial growth by preventing protein synthesis and to minimize toxic side effects of anti-cancer therapy. The study aimed to determine if this combination was an effective treatment for these cancer types.
Trial design
The study (NCT02874430) was a Phase 2 trial that was terminated. It enrolled 29 participants with localized breast carcinoma, endometrial clear cell adenocarcinoma, endometrial serous adenocarcinoma, uterine corpus cancer, or uterine corpus carcinosarcoma. The interventions studied were metformin hydrochloride and doxycycline.
Key results
The trial results, posted on ClinicalTrials.gov, included several key measurements:
- For the outcome "Change in the Percentage of Stromal Cells Expressing Caveolin-1 (CAV1) at an Intensity of 1+ or Greater by Immunohistochemistry," the mean percentage of cells was measured at 61 percentage of cells and 58.3 percentage of cells in the treatment group.
- The "Number of Adverse Events" reported was 18 adverse events.
- For the "Percentage of Tumor Cells That Express Monocarboxylate Transporter 1 (MCT1)," the mean percentage of cells was measured at 41.6 percentage of cells and 38.9 percentage of cells.
- Regarding survival outcomes, 0 participants achieved "Progression-free Survival."
- Similarly, 0 participants achieved "Overall Survival (OS)."
- The "Clinical Response Rate" was observed in 27 participants.
What this means
The termination of this Phase 2 trial, coupled with the reported 0 participants achieving progression-free or overall survival, indicates that the combination of metformin hydrochloride and doxycycline did not demonstrate sufficient efficacy in treating localized breast or uterine cancer within the scope of this study. While adverse events were reported, the primary implication is the lack of positive survival outcomes, leading to the trial's early cessation. These findings suggest that this particular therapeutic approach may not be viable for these cancer types.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT02874430, titled "Metformin Hydrochloride and Doxycycline in Treating Patients With Localized Breast or Uterine Cancer," were posted on 2026-04-22 on clinicaltrials.gov.