Pafolacianine  (Synonyms: OTL 38)

Pafolacianine (OTL 38) is a fluorescent imaging agent made of near-infrared dye used in detecting tumor lesions during surgical procedures. Pafolacianine excites at 774 to 775 nm and emits at 794 to 796 nm^[1][2].

Guide (The following is our recommended protocol. This protocol is provided as a guide only and should be modified to suit your specific needs)^[3].
1. Preparation of dye stock solution
1) Pafolacianine is stored at 1508 μM in a -80°C freezer.
2. Preparation of dye working solution
1) Dilute Pafolacianine in 5% glucose solution within 24 h before use.
2) For the in vivo mouse xenograft model and the ex vivo porcine lung model, prepare working solutions of 0.05 mg/kg, 0.025 mg/kg, and 0.0125 mg/kg by diluting the stock solution in 5% glucose solution.
3. Specific staining steps
3.1 In vivo mouse xenograft model
1) 100 μL of cell mixture (70% KB cell suspension containing 1.0×10⁶ cells in phosphate buffered saline, 30% Matrigel) is subcutaneously inoculated into the right thigh of 8-12 week old female athymic nude mice to establish a subcutaneous xenograft tumor model.
2) Mice are intravenously injected with 0.05 mg/kg, 0.025 mg/kg, or 0.0125 mg/kg of Pafolacianine, or injected with 5% glucose solution as a negative control.
3) Intermittent imaging is performed using UCF at 5, 10, and 15 mm above the tumor (right thigh) and normal limb (left thigh, background) at 6, 24, 48, and 72 h after injection, respectively.
4) Additional NIR imaging is performed using an in vivo whole mouse fluorescence imaging system (Maestro) with 710-760 nm excitation and >800 nm detection.
5) To evaluate biodistribution, mice are sacrificed 24 h after injection, tumors and organs are excised, and fluorescence intensity is assessed using the Maestro system and UCF.
3.2 Ex vivo peribronchial tumor pig model
1) Mice bearing KB tumors with a diameter >10 mm are injected intravenously with 0.025 mg/kg or 0.05 mg/kg of Pafolacianine 24 h before tumor resection.
2) Pafolacianine-loaded KB tumors are excised and transplanted into the peribronchial sites (carina and peripheral airways) of ex vivo porcine lungs. A bronchoscope (BF-P190) is inserted through the endotracheal tube, and the UCF is inserted into the working channel of the bronchoscope.
3) Increase the laser power to 75 mW, acquire NIR fluorescence images in a dark room, and confirm the absence of bronchial wall autofluorescence by UCF using the same settings before tumor placement.

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

1326.49

C₆₁H₆₇N₉O₁₇S₄

785

760

1628423-76-6

Solid

Green to dark green

O=S(CCCCN1C2=CC=C(S(=O)(O)=O)C=C2C(C)(/C1=C/C=C3C(OC4=CC=C(C=C4)C[C@@H](C(O)=O)NC(C5=CC=C(C=C5)NCC(N=C67)=CNC6=NC(N)=NC7=O)=O)=C(CCC\3)/C=C\C8=[N+](C9=CC=C(S(=O)([O-])=O)C=C9C8(C)C)CCCCS(=O)(O)=O)C)(O)=O

Room temperature in continental US; may vary elsewhere.

4°C, protect from light

*In solvent : -80°C, 6 months; -20°C, 1 month (protect from light)

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month (protect from light). When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

• [1]. Jane J Keating, et, al. Intraoperative near-infrared fluorescence imaging targeting folate receptors identifies lung cancer in a large-animal model. Cancer. 2017 May 15;123(6):1051-1060.  [Content Brief]

  [2]. Gul Z, et al. Pafolacianine, the magic wand of intraoperative imaging of folate-receptor positive ovarian cancer. Ann Transl Med. 2023 Oct 25;11(11):394.  [Content Brief]

  [3]. Ishiwata T, et al. Transbronchial real-time lung tumor localization with folate receptor-targeted near-infrared molecular imaging: A proof of concept study in animal models. J Thorac Cardiovasc Surg. 2023 Jun;165(6):e240-e251.  [Content Brief]