• Patients must have pathologically or cytologically confirmed adenoid cystic carcinoma. Cancers arising from non-salivary gland primary sites are allowed.

• Patients must have recurrent and/or metastatic disease not amenable to other curative intent therapy.

• At least 4 weeks must have elapsed since the end of prior systemic treatment and/or 2 weeks since completion of radiotherapy with resolution of all treatment related toxicity to NCI CTCAE Version 5.0 grade \<1 (or tolerable grade 2) or back to baseline (except for alopecia, lymphopenia, or hypothyroidism) prior to starting study drug treatment.

• Patients must have RECIST V1.1 measurable disease, defined as at least one nonnodal lesion measuring ≥ 20 mm with conventional techniques or as ≥10mm with CT scan, MRI, or calipers by clinical exam in the longest dimension AND/OR a nodal lesion measuring ≥ 15 mm in the shortest dimension. Tumors in previously irradiated fields may be considered measurable if there is evidence of tumor progression after radiation treatment.

• Patients must have documentation of a new or progressive lesion on radiologic imaging study performed within 6 months prior to study enrollment (progression of disease over any interval is allowed) and/or new/worsening disease related symptoms within 6 months prior to study enrollment. Note: This assessment will be performed by the treating investigator and evidence of progression by RECIST criteria is not required.

• Age ≥ 18 years of age on the day of signing informed consent.

• ECOG performance status 0 or 1 (or Karnofsky ≥ 70%).

• Patients must have tissue from the primary tumor or metastases available for correlative studies. Either a paraffin block or at least 20 unstained slides are acceptable (paraffin block or at 30 unstained slides would be ideal). Patients without available tissue for submission may still be eligible if approved by the Principal Investigator. Additional tissue collection is not a requirement for this study.

• Screening laboratory values must meet the following criteria:

‣ Neutrophils ≥ 1500/μL

⁃ Platelets ≥ 100x10\^3/μL

⁃ Hemoglobin \> 9.0 g/dL (without packed red blood cell (pRBC) transfusion within the last 2 weeks)

⁃ AST and ALT ≤ 2.5 x ULN (if liver metastases are present, AST and ALT ≤ 5x ULN)

⁃ Total Bilirubin ≤ 1.5 x ULN OR direct bilirubin ≤ ULN for participants with total bilirubin levels \>1.5 x ULN (except participants with Gilbert Syndrome, who can have a total bilirubin \< 3.0 mg/dL)

⁃ Serum creatinine ≤ 1.5 x ULN OR creatinine clearance (CrCl) ≥ 40 mL/min per the Cockcroft-Gault formula if creatinine is \>1.5 x ULN

⁃ Female CrCl = (140 - age in years) x weight in kg x 0.85 72 x serum creatinine in mg/dL

⁃ Male CrCl = (140 - age in years) x weight in kg x 1.00 72 x serum creatinine in mg/dL

• Participants must be willing to sign the written informed consent form. A signed informed consent form must be appropriately obtained prior to the conduct of any trial specific procedure.

• Male participants must agree to use adequate contraception and refrain from donating sperm from start of therapy through 4 months after last dose of trial treatment.

• Female participants must agree not to donate ova starting at screening and throughout the study period, and for at least 3 weeks after the final dose of study drug.

• A female participant is eligible to participate if 1) she is not pregnant (for women of child-bearing potential, a pregnancy test must be negative within 72 hours prior to initiation; if a urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required) OR 2) she is not a woman of child bearing potential as defined by one of the following criteria:

‣ Pre-menopausal with one of the following: documented hysterectomy, documented bilateral salpingectomy, documented bilateral oophorectomy

⁃ Postmenopausal females defined as no menses for 12 months without an alternative medical cause. However, in the absence of 12 months of amenorrhea, confirmation with two FSH measurements in the postmenopausal range is required.

• A woman of childbearing potential must use highly effective contraception from the start of therapy through 2 months after the last dose of study medication.