• Male or female subjects age ≥ 18 years with a history of treated colorectal cancer with unresectable metastases of the primary colorectal cancer to other organs.

• If HIV-1 positive, viral load must be \< 50 copies/ml and participant must be on stable ART for at least 3 months.

• Demonstrate positive tumor expression of CCR5 by IHC.

• Adult patients with metastatic colorectal cancer (mCRC) who have been previously treated with fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy, an anti-VEGF therapy, and, if RAS wild-type and medically appropriate, an anti-EGFR therapy.

• Histologically confirmed for microsatellite stable MSS colorectal cancer by PCR, Immunohistochemistry (IHC) or Next-generation sequencing (NGS).

• Have measurable disease per RECIST 1.1

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

• Expected survival of at least three months

• No anti-cancer treatment within the last four weeks or at least 5 half-lives prior to treatment (except for palliative radiation therapy from which the patient has recovered from all adverse events).

⁃ Patients must have adequate organ and bone marrow function within 28 days prior to registration, defined as:

⁃ i. Acceptable liver function:

‣ Total bilirubin ≤ 1.5 × upper limit of normal (ULN) OR direct bilirubin ≤ ULN for participants with total bilirubin levels \> 1.5 × ULN

‣ Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 × ULN (≤ 5 × ULN for participants with liver metastases).

⁃ ii. Acceptable renal function:

⁃ a) GFR ≥ 30 mL/min iii. Acceptable hematologic status:

‣ Hemoglobin ≥ 9 g/dL Note: Criteria must be met without packed red blood cell (pRBC) transfusion within the prior 2 weeks. Participants can be on stable dose of erythropoietin (≥ approximately 3 months).

‣ White blood cells \> 2500/µL

‣ Absolute neutrophil count \> 1500/µL

‣ Platelet count \> 100 000/µL.

⁃ Clinically normal resting 12-lead ECG at Screening Visit or, if abnormal, considered not clinically significant by the Principal Investigator.

⁃ a) No QTC interval exceeding 460 milliseconds (ms) for females, no QTC interval exceeding 450 ms for males.

⁃ Both male and female patients and their partners of childbearing potential must agree to use two medically accepted methods of contraception (e.g., barrier contraceptives \[male condom, female condom, or diaphragm with a spermicidal gel\], hormonal contraceptives \[implants, injectables, combination oral contraceptives, transdermal patches, or contraceptive rings\], or one of the following methods of birth control (intrauterine devices, tubal sterilization or vasectomy) or must practice complete abstinence from intercourse of reproductive potential from study entry to 6 months after the last day of treatment (excluding women who are not of childbearing potential and men who have been sterilized).

⁃ Females of childbearing potential (FOCBP) must have a negative serum pregnancy test at Screening Visit and negative urine pregnancy test prior to receiving the first dose of study.

⁃ Male participants must agree to use contraception and refrain from donating sperm for at least 120 days after the last dose of study intervention.

⁃ Patients must have the ability to understand and the willingness to sign a written informed consent prior to registration on study.