Allogeneic Hematopoietic Cell Transplantation With Pegylated Interferon Alfa-2a for Primary and Secondary Myelofibrosis

Inclusion Criteria:

Pre-Transplant Inclusion Criteria (Step 1)

• Male or female subject aged ≥ 18 years.

• Diagnosis of primary or secondary myelofibrosis.

• Eligible to undergo a myeloablative or reduced intensity conditioning regimen (MACor RIC)

• Eligible to undergo a standard of care bone marrow biopsy with aspirate as part ofhis or her routine pre-transplant work-up.

• Peripheral blood stem cell (PBSC) graft

• 10/10 HLA matched related or matched unrelated donor

• ECOG performance status ≤ 2.

• For female subjects: Negative pregnancy test or evidence of post-menopausal status.The post-menopausal status will be defined as having been amenorrheic for 12 monthswithout an alternative medical cause. The following age-specific requirements apply:

• Women < 50 years of age:

• Amenorrheic for ≥ 12 months following cessation of exogenous hormonaltreatments; and

• Luteinizing hormone and follicle-stimulating hormone levels in thepost-menopausal range for the institution; or

• Underwent surgical sterilization (bilateral oophorectomy or hysterectomy).

• Women ≥ 50 years of age:

• Amenorrheic for 12 months or more following cessation of all exogenoushormonal treatments; or

• Had radiation-induced menopause with last menses >1 year ago; or

• Had chemotherapy-induced menopause with last menses >1 year ago; or

• Underwent surgical sterilization (bilateral oophorectomy, bilateralsalpingectomy, or hysterectomy).

• Female subjects of childbearing potential and male subjects with a sexual partner ofchildbearing potential must agree to use a highly effective method of contraceptionas described in Section 5.4.1.

Treatment Inclusion Criteria (Step 2)

• Male or female subject aged ≥ 18 years.

• Diagnosis of primary or secondary myelofibrosis.

• Have undergone a myeloablative or reduced-intensity conditioning regimen (MAC orRIC) and be 50-80 days from Day 0 of transplant at initiation of study therapy.

• Peripheral blood stem cell (PBSC) graft

• 10/10 HLA matched related or matched unrelated donor

• ECOG Performance Status ≤ 2.

• Adequate organ function as defined as:

• Hepatic:

• Total Bilirubin ≤ 1.5x institutional upper limit of normal (ULN)

• AST(SGOT)/ALT(SGPT) ≤ 3 × institutional ULN

• Renal:

• Estimated creatinine clearance ≥ 30 mL/min by Cockcroft-Gault formula:

• TSH and T4 within normal limits or adequately controlled thyroid function.

• For female subjects: Negative pregnancy test or evidence of post-menopausal status.The post-menopausal status will be defined as having been amenorrheic for 12 monthswithout an alternative medical cause. The following age-specific requirements apply:

• Women < 50 years of age:

• Amenorrheic for ≥ 12 months following cessation of exogenous hormonaltreatments; and

• Luteinizing hormone and follicle-stimulating hormone levels in thepost-menopausal range for the institution; or

• Underwent surgical sterilization (bilateral oophorectomy or hysterectomy).

• Women ≥ 50 years of age:

• Amenorrheic for 12 months or more following cessation of all exogenoushormonal treatments; or

• Had radiation-induced menopause with last menses >1 year ago; or

• Had chemotherapy-induced menopause with last menses >1 year ago; or

• Underwent surgical sterilization (bilateral oophorectomy, bilateralsalpingectomy, or hysterectomy).

• Female subjects of childbearing potential and male subjects with a sexual partner ofchildbearing potential must agree to use a highly effective method of contraceptionas described in Section 5.4.1.

• Male subjects must agree to use a condom during intercourse for the duration ofstudy therapy as described in Section 5.4.1.

• Recovery to baseline or ≤ Grade 1 CTCAE v5.0 from toxicities related to any priorcancer therapy, unless considered clinically not significant by the treatinginvestigator.

• Able to provide informed consent and willing to sign an approved consent form thatconforms to federal and institutional guidelines.

Exclusion Criteria:

Exclusion Criteria (Step 2)

• Receiving other investigational agents concurrently

• Prior systemic anti-cancer therapy or any investigational therapy within fivehalf-lives prior to starting study treatment.

• Prior radiotherapy within 6 weeks prior to the first dose of study treatment.

• Major surgery within 6 weeks prior to starting study drug or patients who have notfully recovered from major surgery.

• The diagnosis of another malignancy within ≤ 2 years before study enrollment, exceptfor those considered to be adequately treated with no evidence of disease orsymptoms and/or will not require therapy during the study duration (i.e., basal cellor squamous cell skin cancer, carcinoma in situ of the breast, bladder or of thecervix, or low-grade prostate cancer with Gleason Score ≤ 6).

• Current evidence of uncontrolled, significant intercurrent illness including, butnot limited to, the following conditions:

• Graft-versus-host disease: ---Acute or chronic

• Cardiovascular disorders:

• Congestive heart failure New York Heart Association Class III or IV,unstable angina pectoris, serious cardiac arrhythmias.

• Stroke (including transient ischemic attack [TIA]), myocardial infarction (MI), or other ischemic events, or thromboembolic event (eg, deep venousthrombosis, pulmonary embolism) within 3 months before the first dose.

• QTc prolongation defined as a QTcF > 500 ms.

• Known congenital long QT.

• Left ventricular ejection fraction < 55%.

• Uncontrolled hypertension defined as ≥ 140/90 as assessed from the mean ofthree consecutive blood pressure measurements taken over 10 minutes.

• Any other condition that would, in the Investigator's judgment, contraindicatethe subject's participation in the clinical study due to safety concerns orcompliance with clinical study procedures (e.g., infection/inflammation,intestinal obstruction, unable to swallow medication, [subjects may not receivethe drug through a feeding tube], social/ psychological issues, etc.)

• Active infection including HIV, tuberculosis (clinical evaluation that includesclinical history, physical examination, radiographic findings, and TB testing inline with local practice) or hepatitis C.

• Note: Subjects with a past or resolved HBV infection (defined as the presence ofhepatitis B core antibody [anti-HBc] and absence of HBsAg) are eligible.

• Autoimmune hepatitis or decompensated hepatic disease

• Medical, psychiatric, cognitive, or other conditions that may compromise thesubject's ability to understand the subject information, give informed consent,comply with the study protocol or complete the study.

• Known prior severe hypersensitivity to investigational product (IP) or any componentin its formulations (NCI CTCAE v5.0 Grade ≥ 3).

• Subjects taking prohibited medications as described in Section 6.5.1. A washoutperiod of prohibited medications for a period of at least five half-lives or asclinically indicated should occur before the start of treatment.

• History of neuropsychiatric disease, autoimmune disease, or pancreatitis.

• Presence of active interstitial lung disease or pneumonitis, bronchiolitisobliterans, pulmonary hypertension, ulcerative and hemorrhagic/ischemic colitis, andophthalmologic disorders.