Study of Healthy Donor FMT (hdFMT) and Pembrolizumab in Relapsed/Refractory (R/R) PD-L1 Positive NSCLC

The study evaluating the addition of Healthy Donor FMT (hdFMT) to pembrolizumab in PD-1 R/R NSCLC will be conducted over a 104-week period. Patients with anti-PD-1 R/R NSCLC are eligible to enroll. Prior exposure to microbiome modulating therapy is exclusionary. Suitable patients will be identified at the time of progression upon PD-1 monotherapy or PD-1 containing regimens. Patients will undergo a 35-day screening evaluation consisting of systemic staging scans, tumor biopsy, stool/blood serologic studies to confirm suitability. Once enrolled, patients will be seromatched with a suitable donor. Suitable donors are advanced cancer patients who have undergone PD-1 monotherapy and are currently in durable remission (median PFS \>24 months from initiation of PD-1 therapy) with no ongoing irAE as delineated below. Patients will receive Healthy Donor FMT (hdFMT) (induction) via colonoscopy on C1D1 and C3D1. R-FMT (maintenance) via sigmoidoscopy on C4D1 and will be repeated every 9 weeks. All patients will additionally receive pembrolizumab at 200mg every three weeks. Patients will be treated until disease progression or intolerable toxicity or completion of 2 years of therapy, whichever comes first.