A phase II, multicenter, open-label trial of OTL38 injection for the intra-operative imaging of folate receptor-alpha positive ovarian cancer

Gynecol Oncol. 2019 Oct;155(1):63-68. doi: 10.1016/j.ygyno.2019.07.010. Epub 2019 Jul 27.


Purpose: OTL38 is a folate-indole-cyanine green-like conjugate to folate receptor alpha (FRa). The objectives of this prospective trial were to assess the safety and efficacy (sensitivity and positive predictive value (PPV)) of OTL38 for intraoperative imaging during epithelial ovarian cancer surgery.

Methods: Patients with suspected ovarian cancer planned for cytoreductive surgery were eligible to receive OTL38. Near-infrared (NIR) imaging was used to visualize target lesions that were evaluated by two blinded pathologists. A modified intent to treat (mITT) population of lesions from all patients who received OTL38-NIR imaging, underwent surgery, and had at least one FRa + target lesion was used to determine sensitivity and PPV. Two generalized linear models, with and without random effects, were employed to estimate sensitivity and PPV.

Results: Forty-four patients were evaluated for safety, and 225 lesions from 29 patients (the mITT population) were evaluated for efficacy. When assuming no correlation of interlesional results within a patient, sensitivity was estimated at 85.93% (95% lower boundary CI = 81.19) and PPV at 88.14% (95% lower boundary CI = 83.59). When controlling for actual correlation of detection among multiple lesions within a single patient (a random effect), sensitivity was estimated at 97.97% (95% lower boundary CI = 87.75) and PPV at 94.93% (95% lower boundary CI = 86.13). A total of 48.3% [14/29, (95% CI 0.29-0.67)] of patients had at least one additional lesion detected by OTL38 alone. Eight patients had mild drug-related adverse events including infusion reaction, nausea, vomiting, and abdominal pain.

Conclusions: OTL38-NIR was safe and efficacious in this phase II study regardless of folate expression levels and merits phase III evaluation.

Keywords: Cytoreductive surgery; Imaging biomarker; OTL38; Ovarian cancer.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Ovarian Epithelial / diagnostic imaging*
  • Carcinoma, Ovarian Epithelial / surgery*
  • Coloring Agents
  • Cytoreduction Surgical Procedures / methods
  • Female
  • Folate Receptor 1 / analysis*
  • Folic Acid
  • Humans
  • Indocyanine Green*
  • Middle Aged
  • Ovarian Neoplasms / diagnostic imaging*
  • Ovarian Neoplasms / surgery*
  • Prospective Studies
  • Spectroscopy, Near-Infrared
  • Surgery, Computer-Assisted / methods


  • Coloring Agents
  • FOLR1 protein, human
  • Folate Receptor 1
  • Folic Acid
  • Indocyanine Green