A Study of a Personalized Neoantigen Cancer Vaccine

Tumors harboring non-synonymous deoxyribonucleic acid (DNA) mutations can present peptides
containing these mutations as non-self antigens in the context of HLA on the tumor cell
surface. A fraction of mutated peptides result in neoantigens capable of generating T-cell
responses that exclusively target tumor cells. Sensitive detection of these mutations allows
for the identification of neoantigens unique to each patient's tumor to be included in a
personalized cancer vaccine that targets these neoantigens. This vaccine regimen uses two
vaccine vectors as a heterologous prime/boost approach (GRT-C901 first followed by GRT-R902)
to stimulate an immune response. This study will explore the safety and early clinical
activity of this patient-specific immunotherapy intended to induce T-cell responses specific
for neoantigens.

Inclusion Criteria:

- Provide a signed and dated informed consent form prior to initiation of study-specific
procedures.

- Patients with the indicated advanced or metastatic solid tumor as follows:

1. NSCLC who are planned for or have received no more than 1 cycle of systemic
treatment with cytotoxic, platinum-based chemotherapy

2. GEA who are planned for or have received no more than 1 cycle of systemic
treatment with cytotoxic, platinum-based chemotherapy

3. mUC who are planned for or have received no more than 1 cycle of systemic
treatment with cytotoxic, platinum-based chemotherapy

4. CRC-MSS who are receiving first line systemic therapy or who are planned for or
have received no more than 1 cycle of second line systemic therapy including a
fluoropyrimidine and oxaliplatin or irinotecan

- 18 years of age or older

- ECOG Performance Status 0 or 1

- Lesion amenable to biopsy

- Measurable disease according to RECIST v1.1

- Have adequate organ function, as measured by laboratory values (criteria listed in
protocol)

Exclusion Criteria:

- Tumors with genetic characteristics as follows:

1. For NSCLC, patients with a known genetic driver alteration in EGFR, ALK, ROS1,
RET, or TRK

2. For CRC and GEA, patients with MSI disease

3. For CRC, patients with a known BRAF V600E mutation or patients with peritoneal
carcinomatosis

- Patients with known central nervous system (CNS) metastases and/or carcinomatous
meningitis

- Known exposure to chimpanzee adenovirus or any history of anaphylaxis in reaction to a
vaccination

- Bleeding disorder (eg., factor deficiency, coagulopathy) or history of significant
bruising or bleeding following IM injections or blood draws

Complete inclusion and exclusion criteria are listed in the clinical study protocol.