A Phase 1 Study of Ruxolitinib, Steroids and Lenalidomide for Relapsed/Refractory Multiple Myeloma (RRMM) Patients

Multiple myeloma (MM), a plasma cell dyscrasia, is the most common primary malignancy of the
bone marrow.The etiology of myeloma is largely unknown, although genetic predisposition and
environmental factors have been speculated. MM arises from malignant plasma cells that
clonally expand and accumulate in the bone marrow. These clonal plasma cells produce high
levels of monoclonal immunoglobulins. Plasma cell dyscrasias are classified as monoclonal
gammopathy of undetermined significance, solitary plasmacytoma, smoldering myeloma, active
myeloma, extra-skeletal myeloma, or plasma cell leukemia.

In 2015 an estimated 26,850 adults (14,090 men and 12,760 women) in the United States will be
diagnosed with multiple myeloma. It is estimated that 11,240 deaths (6,240 men and 5,000
women) from this disease will occur this year.

In recent years, new and more effective drugs have become available for the treatment of MM.
Such drugs have been evaluated together and in combination with older agents, rapidly
increasing the number of therapeutic options available to MM patients, and resulting in an
improvement in their overall survival (OS) rates. Among the drugs that have been FDA approved
specifically for myeloma are the immunomodulatory agents (IMiDs) thalidomide, and its newer
analogs lenalidomide and pomalidomide.

IMiDs exert their anti-neoplastic action by affecting various cancer cell functions and the
microenvironment, including cytokine production, immune cell function, and in some instances,
inflammation, cell proliferation and cell death. The IMiD thalidomide has been found to be
effective as an anti-MM agent in one-third of myeloma patients; notably, higher response
rates have been observed when combined with steroids. Lenalidomide is an analog of
thalidomide that has shown more potent anti-MM activity than thalidomide in preclinical
studies, and has been FDA-approved for the treatment of previously untreated as well as
relapsed or refractory MM (RRMM) in combination with dexamethasone. Recently, an analog of
thalidomide and lenalidomide, pomalidomide, has also been approved for RRMM patients.

The 5-year survival rate for MM patients has increased from 25% in 1975 to 34% in 2003 and is
currently closer to 40% due to these newer and more effective treatment options.
Unfortunately, even with these newer agents, responses to therapy are transient, and MM
remains an incurable disorder with an eventual fatal outcome; and, therefore, new therapies
are urgently needed.

JAK2 is an intra-cytoplasmic tyrosine kinase that belongs to the Janus kinase family. JAK
kinases play a major role in the transmission of signals from cytokine and growth factor
receptors into the nucleus. JAK kinases activate several intracellular signaling proteins,
among which the STAT transcription factors are well defined. The JAK/STAT pathway mediates
diverse cellular events that affect cell growth, differentiation and cell survival.

Abnormal JAK2 activation has been implicated in several hematological disorders and
malignancies. Mutations, gene translocations or cytokines released by bone marrow stromal
cells, may all result in aberrant JAK2 activation. The activating JAK2 V617F mutation results
in uncontrolled cytokine and growth factor signaling, and is believed to play a key role in
the pathophysiology of myeloproliferative neoplasms. Constitutive JAK2 activation through
specific chromosomal translocations is thought to contribute to the development of leukemia,
lymphoma and multiple myeloma. In MM, elevated levels of cytokines and growth factors such as
interleukin-6 (IL 6), vascular endothelial growth factor, insulin-like growth factor-1, basic
fibroblast growth factor, IL-1, IL-10, IL-11, IL-15, IL-21, granulocyte macrophage colony
stimulation factor, interferon-α, and leukemia inhibitory factor may also contribute to
exacerbated JAK2 activation.11 Among these cytokines, IL-6 has been most widely studied and
is considered to be a growth and survival factor for myeloma cells. Binding of IL-6 to the
IL-6 receptor activates JAK2, which in turn can phosphorylate the IL-6 receptor, thereby
augmenting its downstream signaling effects. Thus, pharmacological inhibition of JAK1/2 may
be a promising therapeutic strategy for treatment of MM.

In this context, treatment of MM cell lines and patient derived primary MM cells with various
JAK1/JAK2, JAK2 and JAK pan specific inhibitors (e.g. INCB16562, CYT387 and TG101209) has
been shown to inhibit cell proliferation. Furthermore, JAK inhibitors have demonstrated
synergistic activity with established anti MM therapies such as melphalan and bortezomib
(CYT387) or melphalan, bortezomib and dexamethasone (INCB16562), in both MM cell lines and
patient derived primary MM cells. Sensitization of MM cells to dexamethasone in response to
JAK inhibitors may occur through crosstalk between the JAK/STAT pathway and glucocorticoids.
In this regard, dexamethasone treatment has been shown to increase STAT3 and the pro survival
factor phosphatidylinositol-3 kinase (PI3K) levels in melanoma cells; in turn, PI3K was found
to increase STAT3 levels. Prolonged exposure to dexamethasone results in resistance, which
could be overcome, at least in part, by JAK/STAT inhibition.

Ruxolitinib is an oral, selective inhibitor of JAK1 and JAK2, and is the only JAK1/2
inhibitor approved by the US FDA for the treatment of intermediate and high-risk
myelofibrosis. Pilot experiments carried out in our research laboratory at the Institute for
Myeloma and Bone Cancer Research have demonstrated that the JAK2 inhibitor ruxolitinib in
combination with lenalidomide and dexamethasone inhibited the proliferation of the MM cell
lines U266 and RPMI8226 and primary tumor cells derived from MM patients, and that this
inhibition was greater than that achieved with these drugs as single agents. Enhanced
anti-tumor activity was also observed when these three drugs were administered together to
severe combined immunodeficient mice bearing LAGκ-1A (bortezomib- and melphalan-sensitive) or
LAGĸ-2 (bortezomib- and melphalan-resistant) human myeloma tumors, both of which were
originally derived from fresh bone marrow biopsies from MM patients. In addition, ruxolitinib
as a single agent showed no anti MM effects whereas the combination of this drug with
dexamethasone showed enhanced anti-MM effects compared to steroid treatment alone. Finally,
an elderly heavily pre treated MM patient with polycythemia rubra vera (PRV), who had
previously received single-agent ruxolitinib while progressing from MGUS to MM and then
subsequently failed treatment with lenalidomide and methylprednisolone, responded to the
addition of low dose ruxolitinib twice daily to these two drugs.

Together, these results suggest that ruxolitinib may overcome lenalidomide and steroid
resistance for RRMM patients that are failing therapy from steroids alone or in combination
with lenalidomide. Therefore, in this phase 1 trial, the investigators will evaluate the
safety and efficacy of ruxolitinib in combination with methylprednisolone and lenalidomide.

Inclusion Criteria:

- Subjects must meet all of the following inclusion criteria to be eligible to enroll in
this study.

1. Has a diagnosis of MM based on standard criteria18 as follows:

Major criteria:

1. Plasmacytomas on tissue biopsy.

2. Bone marrow plasmacytosis (greater than 30% plasma cells).

3. Monoclonal immunoglobulin spike on serum electrophoresis IgG greater than 3.5 g/dL or
IgA greater than 2.0 g/dL or kappa or lambda light chain excretion greater than 1
g/day on 24 hour urine protein electrophoresis.

Minor criteria:

1. bone marrow plasmacytosis (10% to 30% plasma cells)

2. monoclonal immunoglobulin present but of lesser magnitude than given under major
criteria

3. lytic bone lesions

4. normal IgM less than 50 mg/dL, IgA less than 100 mg/dL, or IgG less than 600 mg/dL

Any of the following sets of criteria will confirm the diagnosis of multiple myeloma:

- any 2 of the major criteria

- major criterion 1 plus minor criterion 2, 3, or 4

- major criterion 3 plus minor criterion 1 or 3

- minor criteria 1, 2, and 3, or 1, 2, and 4 2. Currently has MM with measurable
disease, defined as:

- a monoclonal immunoglobulin spike on serum electrophoresis of at least 0.5 g/dL and/or

- urine monoclonal protein levels of at least 200 mg/24 hours

- for patients without measurable serum and urine M-protein levels, an involved SFLC >
100 mg/L or abnormal SFLC ratio 3. Currently has progressive MM

MM patients that are relapsed or have refractory disease from at least 3 regimens or lines
of therapy including an IMID and a proteasome inhibitor, are eligible for enrollment
provided they fulfill the other eligibility criteria:

- Patients are considered relapsed, when they progress greater than 8 weeks from their
last dose of treatment.

- Patients are refractory when they progress while currently receiving the treatment or
within 8 weeks of its last dose.

4. Previous exposure to lenalidomide independent of the response 5. The patient is not
a candidate for a transplant 6. Understand and voluntarily sign an informed consent
form before receiving any study-related procedure that is not part of normal medical
care, with the understanding that consent may be withdrawn at any time without
prejudice to their future medical care.

7. Able to adhere to the study visit schedule and other protocol requirements 8. ECOG
performance status of ≤ 2 at study entry 9. Life-expectancy of greater than 3 months
10. Laboratory test results within these ranges at Screening and confirmed at
enrollment prior to drug dosing on Cycle 1, Day 1:

- Absolute neutrophil count ≥ 1.5 x 109/L; if the bone marrow is extensively infiltrated
( ≥ 70% plasma cells) then ≥ 1.0 x 109/L

- Platelet count ≥ 75 x 109/L; if the bone marrow is extensively infiltrated ( ≥ 70%
plasma cells) then ≥ 50 x 109/L patients must not have received platelet transfusion
for at least 7 days prior to receiving screening platelet count

- Hemoglobin ≥ 8.0 g/dL within 21 days prior to enrollment. Use of erythropoietic
stimulating factors and red blood cell (RBC) transfusions per institutional guidelines
is allowed; however, most recent RBC transfusion must have been at least 7 days prior
to obtaining screening hemoglobin.

- Calculated or measured creatinine clearance (CrCl) of ≥ 60 mL/minute as calculated by
Cockcroft-Gault method (Appendix 3).

- Total bilirubin levels ≤ 2.0 mg/dL (normal levels)

- AST (SGOT) and ALT (SGPT) ≤ 2 x ULN

- Serum potassium within the normal range 11. Patients must be registered into the
mandatory REVLIMID REMS™ program, and be willing and able to comply with the
requirements of the REVLIMID REMS™ program 12. FCBP† must have a negative serum or
urine pregnancy test with a sensitivity of at least 25 mIU/mL within 10 - 14 days
prior to and again within 24 hours of starting ruxolitinib and must either commit to
continued abstinence from heterosexual intercourse or use acceptable methods of birth
control, one highly effective method and one additional effective method AT THE SAME
TIME, and at least 28 days before she starts taking ruxolitinib with or without
lenalidomide. FCBP must also agree to ongoing pregnancy testing. Men must agree to use
a latex condom during sexual contact with a FCBP even if they have had a vasectomy.
All subjects must be counseled at a minimum of every 28 days about pregnancy
precautions and risks of fetal exposure.

- A FCBP (female of childbearing potential) is a sexually mature woman who: 1) has
not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been
naturally postmenopausal for at least 24 consecutive months (i.e., has had menses
at any time in the preceding 24 consecutive months) 13. Able to take aspirin
(acetylsalicylic acid, ASA) at 81 or 325 mg/daily as antiplatelet therapy if
platelet count is above 30 x 109/L (subjects intolerant to ASA may use warfarin
or low molecular weight heparin)

Exclusion Criteria:

- Subjects meeting any of the following exclusion criteria are not to be enrolled in the
study:

1. POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein,
and skin changes) 19

2. Plasma cell leukemia (> 2.0 × 109/L circulating plasma cells by standard
differential)

3. Primary amyloidosis

4. Non-hematologic malignancy within the past 5 years with the exception of a)
adequately treated basal cell carcinoma, squamous cell skin cancer, or thyroid
cancer; b) carcinoma in situ of the cervix or breast; c) prostate cancer of
Gleason Grade 6 or less with stable prostate-specific antigen levels; or d)
cancer considered cured by surgical resection or unlikely to impact survival
during the duration of the study, such as localized transitional cell carcinoma
of the bladder or benign tumors of the adrenal or pancreas

5. Impaired cardiac function or clinically significant cardiac diseases, including
any one of the following:

- Myocardial infarction within 6 months prior to enrollment

- New York Heart Association (NYHA) Class II or greater heart failure or
uncontrolled angina

- Clinically significant pericardial disease

- Severe uncontrolled ventricular arrhythmias

- Echocardiogram or MUGA evidence of LVEF below institutional normal within 28
days prior to enrollment

- Electrocardiographic evidence of acute ischemia or active conduction system
abnormalities. Prior to study entry, any ECG abnormality at Screening has to
be documented by the investigator as not medically relevant.

6. Severe hypercalcemia, i.e., serum calcium ≥ 12 mg/dL (3.0 mmol/L) corrected for
albumin

7. Any serious medical condition, laboratory abnormality, or psychiatric illness
that would prevent the subject from signing the informed consent form

8. Any condition, including the presence of laboratory abnormalities, which places
the subject at unacceptable risk if he/she were to participate in the study or
confounds the ability to interpret data from the study

9. Undergone major surgery within 28 days prior enrollment or has not recovered from
side effects of such therapy (vertebroplasty or kyphoplasty is not considered to
be a major surgery; however, the investigator is to discuss enrollment of a
subject with a recent history of kyphoplasty with the medical monitor).

10. Pregnant or breast feeding females (lactating females must agree not to breast
feed while taking lenalidomide)

11. Received the following prior therapy:

- Chemotherapy within 3 weeks of study drugs

- Corticosteroids (>20 mg/daily prednisone or equivalent) within 3 weeks of
study drugs to ensure that steroid dose intensity at the beginning of the
treatment is not altered by administration of steroids prior to the study.
Consumption of steroids within 3 weeks of the treatment may interfere with
efficacy and side effects due to differences of steroid intensity.

- Immunotherapy or antibody therapy as well as thalidomide, lenalidomide,
arsenic trioxide, or bortezomib within 21 days before study drugs

- Extensive radiation therapy within 28 days before study drugs. Receipt of
localized radiation therapy does not preclude enrollment.

- Use of any other experimental drug or therapy within 28 days of study drugs

- Strong or moderate CYP3A4 inhibitors, strong or moderate CYP3A4 inducers and
fluconazole doses >200 mg daily within 28 days of study drugs.

12. Known hypersensitivity to compounds of similar chemical or biological composition
to thalidomide and lenalidomide or steroids.

13. Concurrent use of other anti-cancer agents or treatments

14. The development of erythema nodosum if characterized by a desquamating rash while
taking thalidomide or similar drugs

15. Known positivity for human immunodeficiency virus (HIV), hepatitis B or C, and
/or active tuberculosis (TB) including subjects with latent TB or with the risk
factor for activation of latent TB.