A Study of CLN-619 (Anti-MICA/MICB Antibody) in Patients With Relapsed and Refractory Multiple Myeloma

Inclusion Criteria:

1. Aged ≥ 18 years at the time of signing the ICF.

2. Willing and able to give written informed consent and adhere to protocolrequirements.

3. Patient has a history of multiple myeloma with relapsed and refractory disease asdefined by the protocol.

4. Patients must have measurable disease (as determined by the local laboratory) asdefined by the protocol.

5. Performance status of 0 to 2 based on the Eastern Cooperative Oncology Group (ECOG)performance scale.

6. Estimated life expectancy of 12 weeks or longer.

7. Prior palliative radiotherapy must have been completed at least 14 days prior todosing on Cycle 1 Day 1.

8. Toxicities related to prior study therapy should have resolved to Grade 1 or lessaccording to criteria of NCI CTCAE v5.0, except for alopecia. Patients with chronicbut stable Grade 2 toxicities may be allowed to enroll after an agreement betweenthe Investigator and Sponsor.

9. Have adequate liver and kidney function and hematological parameters within a normalrange as defined by the protocol.

Exclusion Criteria:

1. Patient has symptomatic central nervous system involvement of MM.

2. Patient has nonsecretory MM, plasma cell leukemia, Waldenstrom's macroglobulinemia,POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein,and skin changes), or amyloidosis.

3. Patient had a prior autologous stem cell transplant ≤ 3 months prior to first doseof study drug on Cycle 1 Day 1.

4. Patient had a prior allogeneic stem cell transplant with either standard or reducedintensity conditioning ≤ 6 months prior first dose of study drug on Cycle 1 Day 1 oris on systemic immunosuppression for graft-versus-host disease.

5. Patients with concomitant second malignancies (Except adequately treatednon-melanomatous skin cancers, ductal carcinoma in situ, superficial bladder cancer,prostate cancer, Grade 1 stage 1A/1B endometrioid endometrial cancer or cervicalcancer in situ) are excluded unless in complete remission three years prior to studyentry, and no additional therapy is required or anticipated to be required duringstudy participation.

6. Patients with any active autoimmune disease or a history of known or suspectedautoimmune disease, or history of a syndrome that requires systemic corticosteroidstreatment or immunosuppressive medications, except for patients with vitiligo,resolved childhood asthma/atopy or autoimmune thyroid disorders on stable thyroidhormone supplementation.

7. A serious uncontrolled medical disorder that would impair the ability of the patientto receive protocol therapy or whose control may be jeopardized by the complicationsof this therapy.

8. Treatment with systemic antiviral, antibacterial or antifungal agents for acuteinfection within ≤ 7 days of first dose of study drug on Cycle 1 Day 1.

9. Patient has active peripheral neuropathy or neuropathic pain Grade 2 or higher, asdefined by the NCI-CTCAE v5.0.

10. Diagnosed with HIV, Hepatitis B, or Hepatitis C infection.

11. Treatment with non-oncology vaccines for the control of infectious diseases (i.e.,HPV vaccine) within 28 days of first dose of study drug on Cycle 1 Day 1.

12. Active SARS-CoV-2 infection based on positive SARS-CoV-2 test within 4 weeks priorto enrollment or patients with suspected active infection based on clinical featuresor pending results.

13. Has received immunosuppressive medications including but not limited to CellCept,methotrexate, infliximab, anakinra, tocilizumab, cyclosporine, or corticosteroids (≥ 10 mg/day of prednisone or equivalent), within 28 days of first dose of study drugon Cycle 1 Day 1.

14. Patient has history of drug-related anaphylactic reactions to any components ofCLN-619. History of Grade 4 anaphylactic reaction to any monoclonal antibodytherapy.

15. Certain treatment with investigational agents and other anti-neoplastic therapy asdefined by the protocol

16. Female of child-bearing potential (FOCBP) who is pregnant or breast-feeding, plansto become pregnant within 120 days of last study drug administration or declines touse an acceptable method to prevent pregnancy during study treatment and for 120days after the last dose of study drug administration.

17. Male patients who plans to father a child or donate sperm within 120 days or 5half-lives of CLN-619, whichever comes later, of last study drug administration, orwho has a partner who is a FOCBP, and declines to use an acceptable method toprevent pregnancy during study treatment and for 120 days or 5 half-lives ofCLN-619, whichever comes later, after the last dose of study drug administration.