Neo-adjuvant Pembrolizumab in Vulvar Squamous Cell Carcinoma: a Clinical Proof-of-concept Study

Inclusion Criteria: 1. Signed written informed consent prior to performance of study-specific procedures or assessments, and must be willing to comply with treatment and follow-up assessments. 2. Age ≥ 18 years old at the day of signing informed consent 3. Histologically confirmed primary vulvar squamous cell carcinoma, with all of the following characteristics: * At least 1 lesion that can be measured in at least 1 dimension with ≥ 10 mm in largest diameter. * Clinically stage FIGO I-III. * Documentation confirming the absence of distant metastasis (M0) as determined by institutional practice. Routine exams to discard metastases will be performed according to Investigator judgement but are mandatory in case of suspicion of metastatic disease. * Vulvar cancer eligible for primary surgery * In the case of a multifocal tumor (defined as the presence of two or more foci of cancer on the vulva), the largest lesion must be ≥ 10 mm and all lesions ≥ 10 mm are designated as "target" lesion(s) for all subsequent tumor evaluations and biopsies. 4. ECOG performance 0-1 5. Have adequate organ function as measured within 28 days prior to administration of study treatment. 6. A female participant is eligible to participate if she is not pregnant or breastfeeding, and at least one of the following conditions applies: * Is not a woman of childbearing potential, or * Is a woman of childbearing potential and using a contraceptive method that is highly effective (with a failure rate of \<1% per year), with low user dependency, or be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long-term and persistent basis), as described in Appendix 11 during the intervention period and for at least the time needed to eliminate each study intervention after the last dose of study intervention and agrees not to donate eggs (ova, oocytes) to others or freeze/store for her own use for the purpose of reproduction during this period. The length of time required to continue contraception for each study intervention is 120 days for pembrolizumab. Exclusion Criteria: 1. Locally advanced tumor not amenable to surgical therapy. 2. A woman of child bearing potential who has a positive urine pregnancy test within 72 hours prior to allocation. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required. 3. Prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (eg, CTLA-4, OX 40, CD37) 4. Prior systemic anti-cancer therapy including investigational agents within 4 weeks \[prior to allocation. Note: Participants must have recovered from all AEs due to previous therapies to ≤Grade 1 or baseline. Participants with ≤Grade 2 neuropathy may be eligible. Note: If participant received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting study treatment. 5. Prior radiotherapy within 2 weeks of start of study treatment. Participants must have recovered from all radiation-related toxicities, not require corticosteroids, and not have had radiation pneumonitis. 6. Major surgery within 2 weeks of starting study treatment and patients must have recovered from any effects of any major surgery. 7. A live vaccine within 30 days before the first dose of study intervention. Examples of live vaccines include, but are not limited to, the following: measles, mumps, rubella, varicella/zoster (chicken pox), yellow fever, rabies, Bacillus Calmette- Guérin (BCG), and typhoid vaccine. Seasonal influenza vaccines for injection are generally killed virus vaccines and are allowed; however, intranasal influenza vaccines (eg, FluMist®) are live attenuated vaccines and are not allowed. Please refer to section 5.4 for information on COVID-19 vaccines. 8. Currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study treatment. Note: Participants who have entered the follow-up phase of an investigational study may participate as long as it has been 4 weeks after the last dose of the previous investigational agent. 9. Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior to the first dose of study drug. 10. A known additional malignancy that is progressing or has required active treatment within the past 3 years. Note: Participants with basal cell carcinoma of the skin, squamous cell carcinoma of the skin on a location other than the vulva, or carcinoma in situ (e.g. of the breast , cervix or bladder) that have undergone potentially curative therapy are not excluded. 11. Severe hypersensitivity (≥Grade 3) to pembrolizumab and/or any of its excipients. 12. Active or prior documented autoimmune or inflammatory disorders (including inflammatory bowel disease \[e.g., colitis or Crohn's disease\], diverticulitis \[with the exception of diverticulosis\], systemic lupus erythematosus, Sarcoidosis syndrome, or Wegener syndrome \[granulomatosis with polyangiitis, Graves' disease, rheumatoid arthritis, hypophysitis, uveitis, etc\]). The following are exceptions to this criterion: * Patients with vitiligo or alopecia * Patients with hypothyroidism (e.g., following Hashimoto syndrome) stable on hormone replacement * Any chronic skin condition that does not require systemic therapy * Patients without active disease in the last 5 years may be included but only after consultation with the study physician * Patients with celiac disease controlled by diet alone 13. History of (non-infectious) pneumonitis that required steroids or has current pneumonitis 14. An active infection requiring systemic therapy. 15. Known history of Human Immunodeficiency Virus (HIV). Note: No HIV testing is required unless mandated by local health authority. 16. Known history of Hepatitis B (defined as Hepatitis B surface antigen \[HBsAg\] reactive) or known active Hepatitis C virus (defined as HCV RNA \[qualitative\] is detected) infection. Note: no testing for Hepatitis B and Hepatitis C is required unless mandated by local health authority. 17. A history or current evidence of any condition, therapy, or laboratory abnormality or other circumstance that might confound the results of the study, interfere with the subject's participation for the full duration of the study in such it is not in the best interest of the subject to participate, in the opinion of the treating investigator. 18. Is pregnant or breastfeeding or expecting to conceive within the projected duration of the study, starting with the screening visit through 120 days after the last dose of trial treatment. 19. Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial. 20. Has had an allogenic tissue/solid organ transplant.