Healthy-donor Microbiome MTP-101-C in Steroid Relapse/Refractory Immune-related Cutaneous Adverse Events (irCAEs) and Immune-mediated Colitis (IMC)

Inclusion Criteria:

• Able to swallow oral medication.

• The participant provides written informed consent for the trial.

• Willingness to use contraception for duration of trial participation. Maleparticipants: A male participant must agree to use a contraception per protocolduring the treatment period and for at least 120 days after the last dose of studytreatment and refrain from donating sperm during this period.

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

Not a woman of childbearing potential (WOCBP) per protocol; OR A WOCBP who agrees to follow the contraceptive guidance during the treatment period and for at least 120 days after the last dose of study treatment.

-Clinically confirmed inflammatory irCAE or endoscopically confirmed IMC. Cohort 1 (irCAE): Patients with maculopapular rash, psoriasiform, lichenoid eruptions or bullous pemphigoid of at least grade 3 severity per CTCAE grading system (i.e. >30% BSA with moderate or severe symptoms) during Screening.

Cohort 2 (IMC): Endoscopically confirmed inflammatory colitis as determined by colonoscopy or flexible sigmoidoscopy during Screening with minimum severity per Mayo endoscopic subscore 1-¬3 [MES1-3].

-Prior receipt of anti-PD(L)1 and/or anti-CTLA-4 singly or in combination with other approved or investigational agents including chemotherapy or targeted therapy.

NOTE: Patient may have received or are receiving ICI therapy as standard-of-care or part of a clinical trial.

Patient must have received treatment with an anti-PD-(L)1 ICI, anti-CTLA-4 ICI singly and/or in combination with other approved and/or investigational anti-cancer agent(s), as their most recent therapy prior to development of colitis.

Cohort 1 (steroid relapsed/refractory Grade ≥3 irCAE) only

• Receipt of high-dose systemic corticosteroids defined as 1-2mg/kg prednisoneequivalent daily (either oral or intravenous) with a taper over 4-6 weeks as definedby society consensus guidelines102-105; AND

• No receipt of biologic such as but not limited to (dupilumab, rituximab) prior toenrollment.

• NOTE: Patients must have received steroids to be eligible.

• NOTE: Steroid "resistant" disease: patients whose symptoms responded (reduction in aCTCAE grade) initially but who developed recurrence upon steroid taper ordiscontinuation.

• NOTE: Steroid "refractory" disease: patients whose symptoms have not clinicallyimproved by a CTCAE grade in ≥48 hours or maximum of 14 days.

Cohort 2 (steroid-relapsed/refractory Grade ≥3 IMC) only

• Receipt of high-dose systemic corticosteroids defined as 1-2mg/kg prednisoneequivalent daily (either oral or intravenous) with a taper over 4-6 weeks as definedby society consensus guidelines102-105; AND

• No receipt of biologic such as but not limited to (TNFα inhibitor infliximab OR α₄β₇integrin inhibitor vedolizumab) prior to enrollment.

• Patients must have received steroids to be eligible.

• Steroid "resistant" disease: patients whose symptoms responded (reduction in a CTCAEgrade) initially but who developed recurrence upon steroid taper or discontinuation.

• Steroid "refractory" disease: patients whose symptoms have not clinically improvedby a CTCAE grade in ≥48 hours or maximum of 14 days.

• Patient may have received any number of lines of prior systemic therapy.

• Patient with any solid tumor or hematologic malignancy are eligible.

• Patient must not be receiving concurrent radiation therapy.

• Willingness to undergo cohort-specific evaluation.

• Cohort 1: Dermatologic evaluation, and skin biopsy evaluation prior to and afterMTP-101-C administration.

• Cohort 2: GI evaluation, and endoscopic evaluation including colonoscopies prior toand after MTP-101-C administration.

• Willingness to undergo correlative blood and stool sampling.

• Have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0to 2.

• Patients with ECOG PS 2 wherein the decline in PS from baseline is deemed secondaryto IMC may be enrolled at the discretion of Sponsor-Investigator.

• Patients with ECOG PS 2 wherein PS is at baseline and deemed secondary to diseaseare excluded.

• Have adequate organ function per specimens must be collected within 7 daysprior to the start of study treatment.

Exclusion Criteria:

• Multiple irAEs besides irCAE or IMC.

• Patients with concurrent ≥Grade 3 irAEs besides irCAE or IMC that necessitatesystemic immune suppression are not candidates for this trial.

• Patients with irCAE and/or IMC that are not otherwise clarified in Section 5.1.5 (irCAE including alopecia etc.) are not candidates for this trial.

• Patients with concomitant irAEs that are well controlled (≤Grade 1 or Grade 2on repletion medication) may be enrolled at the discretion ofSponsor-Investigator.

• Diagnosis of immunodeficiency, immunosuppression or any other form ofimmunosuppressive therapy besides steroids/biologics within 7 days prior to thefirst dose of MTP-101-C treatment.

• Patients at high risk of MDRO colonization including: nursing home residence, age >85, underlying diseases (dementia, poorly controlled diabetes, chronic wounds),in-dwelling medical devices (urinary catheters, feeding tubes, PEG tubes) and aprior history of MDRO colonization.

• Contraindication to endoscopy (cohort 2 only).

• Contraindication to MTP-101-C administration.

• Any prior head/neck and/or abdominal surgery resulting in potentially alteredabsorption of orally administered FMT pills.

• Active bacterial infection requiring systemic antibiotic therapy.

• Received live vaccines within 30 days prior to the first dose of study treatment andwhile participating in the study