NFX-179 Topical Gel Treatment in Adults With Neurofibromatosis 1 (NF1) and Cutaneous Neurofibromas (cNF)

Inclusion Criteria:

1. Subject is at least 18 years of age
2. Subject must provide written informed consent prior to any study procedures
3. Subject must have a clinical diagnosis of NF1
4. Subject has 6 Study cNF Tumors (5 Target cNF Tumors \[1 on the face; 4 on the anterior trunk or upper extremities\] that will be treated with the assigned study medication;1 Untreated cNF Tumor on the anterior trunk or upper extremities) that each meet the following criteria:

   * Has, in the investigator's opinion, a clinically typical appearance
   * Is dome shaped
   * Is not pedunculated
   * Is a discrete tumor
   * Is not irritated
   * Is not in an area subject to repeated trauma (e.g., area that is shaved, on the beltline, under a bra strap, etc.)
   * Does not have an active cutaneous infection
   * Has a diameter that is ≥5mm and ≤10mm
   * Has a height of ≥2mm
   * Is, when centered in the center of the provided template, the only cNF tumor visible
   * Is not within 5mm of the orbital rim.
5. Subject is willing to have the 5 Target cNF Tumors and the 1 Untreated cNF Tumor excised at the end of the treatment period
6. Subject is willing to have hair in the area surrounding the Target cNF Tumors shaved, if necessary, to obtain photographs
7. Subject is willing to minimize exposure of each Target cNF to natural and artificial ultraviolet radiation
8. Subject is willing to forego treatment of the Target cNF Tumors, except protocol specified therapy, during the study
9. Female subjects who are women of childbearing potential must have a negative urine pregnancy test result and be willing to use a protocol approved, contraceptive method for the duration of the study
10. Subject is willing and able to follow all study instructions and to attend all study visits.

Exclusion Criteria:

1. Subject has applied any of the following topical products in the previous 30 days on or in proximity to any Study cNF Tumor that, in the investigator's opinion, impairs evaluation of any the tumor or which exposes the subject to an unacceptable risk by study participation:

   * Corticosteroids
   * Retinoids (e.g., tazarotene, tretinoin, adapalene)
   * \> 5% of an alpha-hydroxy acid (e.g., glycolic acid, lactic acid)
   * Fluorouracil
   * Imiquimod
2. Any Study cNF Tumor has ever been treated with an MEK inhibitor or a BRAF inhibitor
3. The subject has used any of the following systemic medications in the noted time period:

   * Retinoids (e.g., etretinate, isotretinoin) within the previous 90 days
   * MEK inhibitors within the previous 180 days
   * BRAF inhibitors within the previous 180 days
4. Subject has a history of hypersensitivity to any of the ingredients in the study medications
5. Subject has any known intercurrent illness or physical condition that would, in the investigator's opinion, impair evaluation of a Target cNF Tumor or which exposes the subject to an unacceptable risk by study participation
6. Subject has, in the investigator's opinion, clinically relevant history of liver disease, including viral hepatitis, current alcohol abuse, or cirrhosis
7. Subject has a history of metastatic disease, or active cancer (excluding nonmelanoma skin cancer, Stage I cervical cancer, ductal carcinoma in situ of the breast, or Stage 0 chronic lymphocytic lymphoma) within the previous 5 years
8. Subject has any condition (e.g., other skin conditions or diseases, metabolic dysfunction, physical examination findings, clinical laboratory findings) or situation (e.g., vacation, scheduled surgery) that would, in the investigator's opinion, impair evaluation of a Target cNF Tumor or which exposes the subject to an unacceptable risk by study participation
9. Subject has participated in an investigational drug trial in which administration of an investigational study medication occurred within the previous 30 days