Open Label Phase 2 Study of Tasquinimod in Patients With Primary Myelofibrosis (PMF), Post-Polycythemia Vera Myelofibrosis (Post-PV MF), or Post-Essential Thrombocytosis Myelofibrosis (Post-ET MF)

Inclusion Criteria:

Participants eligible for inclusion in this study have to meet the following criteria:

Myelofibrosis MF Monotherapy:

Participants who are not candidates for, intolerant of, or relapsed/refractory to approved JAKi (ruxolitinib and / or fedratinib / pacritinib) or when further benefit from therapy is not anticipated per investigator. Participants not eligible for JAKi therapy irrespectively of previous treatments. Prior JAKi therapy is not required.

Myelofibrosis Ruxolitinib Combination MF participants treated with Ruxolitinib for at least 3 months on a stable, uninterrupted dose for at least 2 months prior to study enrollment AND have suboptimal response (palpable spleen of ≥5 cm, or total symptoms score of ≥10) or progressive anemia/thrombocytopenia/neutropenia.

AND all the below criteria in both cohorts:

• Must be diagnosed with treatment requiring PMF or post ET/PV MF diagnosed accordingto the 2016 World Health Organization with intermediate -1, intermediate -2 orhigh-risk disease according to the DIPSS prognostic scoring system, or if with lowrisk disease then with symptomatic splenomegaly that is ≥ 5 cm below left costalmargin by physical exam.

• Peripheral or bone marrow blasts must be < 10%

• Participants must provide written informed consent.

• Age 18 years or older. Because no dosing or adverse event data are currentlyavailable on the use of tasquinimod as monotherapy or in combination withruxolitinib in patients <18 years of age, children are excluded from this study.

• Willing and able to comply with scheduled visits, treatment plan and laboratorytests.

• Participant is able to swallow and retain oral medication.

• ECOG performance status 0-2.

• Required baseline laboratory status:

• Absolute neutrophil count (ANC) ≥ 1.0 x 109/L (1000/mm3)

≤ 1.0 x ULN (upper limit of normal)

• AST (SGOT) or ALT (SGPT) [if both measured, then this applies to bothmeasurements] ≤ 2.5 x ULN, except for participants with MF involvement of theliver who must have levels ≤ 5 x ULN

• Glomerular Filtration Rate (GFR) of ≥ 30 ml/min based on Chronic Kidney DiseaseEpidemiology Collaboration (CKD-EPI) equation using serum or plasma creatinineor cystatin-C.

• Treatment-related toxicities from prior therapies must have resolved to Grade ≤ 1.

• At least 2 weeks from prior investigational MF-directed treatment (till the start ofstudy drug). This excludes concurrent ruxolitinib which is allowed in combinationcohort. Hydroxyurea is allowed as standard cytoreductive therapy up until one dayprior to initiation of therapy with tasquinimod. No other standard of care therapyfor MF is allowed (as specified in the exclusion criteria)

• For women of childbearing potential, a documented negative serum or urine pregnancytest within 14 days prior to the administration of study drug.

• The effects of tasquinimod on the developing human fetus are unknown. For thisreason, women of child-bearing potential and men must agree to use adequatecontraception (hormonal or barrier method of birth control; abstinence) prior tostudy entry and for the duration of study participation. (Refer to PregnancyAssessment Policy MD Anderson Institutional Policy # CLN1114). This includes allfemale participants, between the onset of menses (as early as 8 years of age) and 55years unless the patient presents with an applicable exclusionary factor which maybe one of the following:

• Postmenopausal (no menses in greater than or equal to 12 consecutive months).

• History of hysterectomy or bilateral salpingo-oophorectomy.

• Ovarian failure (Follicle Stimulating Hormone and Estradiol in menopausalrange, who have received Whole Pelvic Radiation Therapy).

• History of bilateral tubal ligation or another surgical sterilizationprocedure.

• Approved methods of birth control are as follows: Hormonal contraception (i.e. birthcontrol pills, injection, implant, transdermal patch, vaginal ring), Intrauterinedevice (IUD), Tubal Ligation or hysterectomy, Subject/Partner post vasectomy,Implantable or injectable contraceptives, and condoms plus spermicide. Not engagingin sexual activity for the total duration of the trial and the drug washout periodis an acceptable practice; however periodic abstinence, the rhythm method, and thewithdrawal method are not acceptable methods of birth control. Should a woman becomepregnant or suspect she is pregnant while she or her partner is participating inthis study, she should inform her treating physician immediately.

• Men treated or enrolled on this protocol must also agree to use adequatecontraception prior to the study, for the duration of study participation, and 6months after completion of tasquinimod administration.

• Ability to understand and the willingness to sign a written informed consentdocument.

Exclusion Criteria:

Participants eligible for this study must not meet any of the following criteria:

• Any concurrent severe and/or uncontrolled medical conditions that could increase theparticipant's risk for toxicity while in the study or that could confounddiscrimination between disease- and study treatment-related toxicities.

• Impaired cardiac function or clinically significant cardiac diseases, including anyof the following:

• History or presence of ventricular tachyarrhythmia.

• Presence of unstable atrial fibrillation (ventricular response > 100 bpm);Participants with stable atrial fibrillation are eligible, provided they do notmeet any of the other cardiac exclusion criteria.

• Clinically significant resting bradycardia (< 50 bpm).

• Angina pectoris or acute myocardial infarction ≤ 3 months prior to startingstudy drug.

• Other clinically significant heart disease (e.g., symptomatic congestive heartfailure; uncontrolled arrhythmia or hypertension; history of labilehypertension or poor compliance with an antihypertensive regimen).

• Participants who are currently receiving chronic (> 14 days) treatment withcorticosteroids at a dose ≥ 10 mg of prednisone (or its glucocorticoid equivalent)per day, or any other chronic immunosuppressive treatment that cannot bediscontinued prior to starting study drug.

• Treatment with chemotherapy (except hydroxyurea within 1 day prior to studytreatment), immunomodulatory drug therapy (e.g. thalidomide, interferon-alpha),platelet-reducing therapy (e.g. anagrelide), immunosuppressive therapy, anderythropoetin use within 28 days prior to study treatment

• Treatment with experimental therapy within the past 2 weeks or 5 half-lives,whichever is shorter

• Treatment with tasquinimod at any time

• Participants with impairment of gastrointestinal (GI) function or GI disease thatmay significantly alter the absorption of tasquinimod as per physician opinion

• Participants with known or active (acute and chronic) Hepatitis A, B, or C; andHepatitis B and C carriers, HIV. Participants are excluded regardless ofdetectability of viral load (lack of safety data).

• Participants with clinically significant bacterial, fungal, parasitic or viralinfection which require therapy

• History of pancreatitis

• History of malabsorption or other condition that would interfere with absorption ofstudy drugs (e.g. ulcerative diseases, uncontrolled nausea, vomiting, diarrhea,malabsorption syndrome, small bowel resection)

• Systemic treatment within 14 days prior to the initiation of study treatment withany of the following moderate or strong inhibitor, or moderate or strong inducer ofcytochrome P-3A4 (CYP3A4): imidazoles (e.g. ketoconazole), protease inhibitors (e.g.ritonavir), macrolides (e.g. erythromycin), rifampicin, rifabutin, phenytoin,carbamazepine, St. John's wort.

• Need for ongoing therapy with any of the following drug substances of narrowtherapeutic range that are metabolized mainly by CYP3A4: alfentanil, fentanyl,quinidine, astemizole, terfenadine, sirolimus, tacrolimus, cyclosporine, cisapride,and ergotamine

• Need for ongoing therapy with any of the following drug substances of narrowtherapeutic range metabolized mainly by CYP1A2: duloxetine, palonosetron,theophylline, tizanidine, and ondansetron.

• Need for ongoing therapy with any of the following drug substances of narrowtherapeutic range metabolized mainly by CYP2D6: Dosulepin, Flecainide, Sotalol,Pimozide, Procainamide, Clonidine, Desipramine, Clomipramine, Amitriptyline,Imipramine, Nortriptyline, Trimipramine, Amoxapine, Dronedarone, Phenytoin

• Ongoing treatment with warfarin, unless the INR is <=3.0.

• Known hypersensitivity to tasquinimod or any excipients in the study treatments

• Any other condition that would, in the Investigator's judgment, contraindicatesubject's participation in the clinical study due to safety concerns or compliancewith clinical study procedures

• Prior inclusion in this study

• Pregnant women are excluded from this study because tasquinimod is an agent with thepotential for teratogenic or abortifacient effects. Because there is an unknown butpotential risk for adverse events in nursing infants secondary to treatment of themother with tasquinimod, breastfeeding should be discontinued if the mother istreated with tasquinimod. These potential risks may also apply to other agents usedin this study.