⁃ Male participants:

⁃ • A male participant must agree to use a contraception as detailed per protocol of this protocol during the treatment period and for at least 120 days after the last dose of study treatment and refrain from donating sperm during this period.

• Female participants:

• • A female participant is eligible to participate if she is not pregnant per protocol, not breastfeeding, and at least one of the following conditions applies:

⁃ Not a woman of childbearing potential (WOCBP); OR

⁃ A WOCBP who agrees to follow the contraceptive guidance per protocol during the treatment period and for at least 120 days after the last dose of study treatment.

• Histologically or cytologically confirmed diagnosis of stage IV PD-L1+ NSCLC.

‣ NOTE: Patients with either squamous or non-squamous NSCLC may enroll.

⁃ NOTE: Documented PD-L1 status (defined as 1% or greater) as determined by immunohistochemistry with anti-PD-L1 antibody (IHC 22C3 pharmDx or other FDA approved diagnostic method) from a core or excisional biopsy (fine needle aspirate is not sufficient).

⁃ NOTE: Patients with small cell, large cell, neuroendocrine and/or sarcomatoid NSCLC are excluded.

• Participants must have progressed on treatment with an anti-PD(L)1 ICI administered either as monotherapy or in combination with other checkpoint inhibitors or other standard/investigational therapies. PD-1 treatment progression is defined by meeting all the following criteria:

‣ Has received at least 2 doses of an approved anti-PD(L)1 ICI administered as a single agent, in combination with chemotherapy, and/or in combination with other investigational therapy.

⁃ Participants who progressed on/within 3 months of adjuvant therapy with anti-PD(L)1 ICI will eligible.

⁃ Demonstrated disease progression after anti-PD-1/L1 as defined by RECIST v1.1. The initial evidence of PD is to be confirmed by a second assessment no sooner than 4 weeks from the date of the first documented PD.

⁃ Progressive disease has been documented within 12 weeks from the last dose of anti-PD-1/anti-PD-L1 mAb.

⁃ NOTE: Progressive disease must be determined as above.

⁃ NOTE: This determination is made by the treating investigator. Once PD is confirmed, the initial date of PD documentation will be considered the date of PD.

⁃ NOTE: Anti-PD(L)1 ICI need not be the most recent line of therapy administered.

• Patients with CNS disease are eligible if CNS metastases are treated and deemed stable prior to date of enrollment.

‣ NOTE: All patients will undergo CNS imaging at the time of Screening. Patients with treated brain metastases will need repeat CNS imaging to document stability.

⁃ NOTE: Stability is defined based on appearance of treated lesions on a contrast-enhanced CT or MRI brain study performed as part of screening by radiologist, radiation oncologist or neurosurgeon (whichever is most appropriate); absence of new or enlarging brain metastases; and no longer requiring systemic steroids (≤ 10 mg/day prednisone or equivalent) for at least one week prior to enrollment.

⁃ NOTE: The contrast-enhanced CT or MRI brain imaging study should be performed no sooner than 2 weeks after most recent surgical and/or radiological intervention.

⁃ NOTE: If lesions were discovered during Screening, the patient may be eligible if the lesions are treated and stable based on the above criteria.

⁃ NOTE: Patients with leptomeningeal involvement (leptomeningeal enhancement on MRI/CT imaging and/or positive CSF cytology) are excluded regardless of stability.

• Prior treatment(s)

‣ NOTE: Prior anti-CTLA-4 ICI is allowed but not required.

⁃ NOTE: Patients with known oncogenic driver (including but not limited to EGFR, ALK, ROS, MET alterations) must have received and progressed past driver-specific therapy

• Willingness to repeatedly receive FMT administered endoscopically (colonoscopy or sigmoidoscopy) and via pills following necessary bowel preparation pre-procedure.

‣ NOTE: Understands infectious risks associated with FMT administration. o Although FMT infusate has been screened for bacteria, viruses, fungi and parasites there is a risk of transmission of known and unknown infectious organisms contained in the donor stool. Post-FMT bacteremia (e.g. E. coli), sepsis and fatal events may rarely occur.

⁃ NOTE: Understands non-infectious risks associated with FMT administration. o Possible allergy and/or anaphylaxis to antigens in donor stool.

‣ o Theoretical risk of developing disease possibly related to donor gut microbiota including but not limited to: obesity, metabolic syndrome, cardiovascular disease, autoimmune conditions, allergic/atopic disorders, neurologic disorders, psychiatric conditions and malignancy.

⁃ NOTE: Understand risks associated with endoscopy (colonoscopy or sigmoidoscopy) including risk of infection transmission, colonic perforation, aspiration pneumonia, and death.

⁃ NOTE: Understand that data regarding the long-term safety risk of FMT are lacking.

• Presence of measurable disease based on RECIST 1.1.

‣ Patients need to have at least one measurable lesion and a separate lesion for biopsy. Patients with only 1 lesion may be enrolled after discussion with Sponsor-Investigator.

⁃ Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions.

• Able to provide newly obtained core or excisional biopsy of a tumor lesion not previously irradiated to undergo tumor biopsy (core, punch, incisional or excisional).

• • Biopsy must meet minimal sampling criteria as defined per protocol.

• Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.

• Have adequate organ function per protocol. Specimens must be collected within 28 days prior to the start of study intervention.

• Criteria for patients with hepatitis B and C

‣ Screening for hepatitis B and C are required.

⁃ For hepatitis B positive patients:

• Patients who are hepatitis B positive (i.e. HBsAg positive) or have a history of history of hepatitis B (i.e. HBcAb positive, or history of documented hepatitis B infection) are eligible if they have received hepatitis B directed antiviral therapy for at least 4 weeks and have undetectable HBV viral load (HBV DNA) prior to enrollment.

∙ Participants should remain on antiviral therapy throughout study intervention and follow local guidelines for HBV antiviral therapy post completion of study intervention.

⁃ For hepatitis C positive patients:

• Patients who are hepatitis C positive (i.e. HCV antibody reactive) or have a history of history of hepatitis C (i.e. history of documented hepatitis C infection) are eligible if they have received and completed hepatitis C directed antiviral therapy at least 4 weeks and have undetectable HCV viral load (HCV RNA) prior to enrollment.