WO2018017410A1

WO2018017410A1 - Combination therapy of abemaciclib and a pi3 kinase/mtor dual inhibitor for use in the treatment of breast cancer

Info

Publication number: WO2018017410A1
Application number: PCT/US2017/042104
Authority: WO
Inventors: Richard Paul Beckmann; Gregory Paul Donoho; Volker Wacheck
Original assignee: Eli Lilly And Company
Priority date: 2016-07-22
Filing date: 2017-07-14
Publication date: 2018-01-25

Abstract

The present invention relates to a dual combination of abemaciclib and a PI3 kinase/MTOR dual inhibitor known in the art as LY3023414, and a triple combination which also adds fulvestant, and to methods of using the dual and triple combinations to treat patients with certain disorders, such as in patients with breast cancer, in particular patients with locally advanced breast cancer or metastatic breast cancer.

Description

COMBINATION THERAPY OF ABEMACICLIB AND A PI3 KINASE/MTOR DUAL INHIBITOR FOR USE IN THE TREATMENT OF BREAST CANCER

The present invention relates to a dual combination of abemaciclib and a PI3 kinase MTOR dual inhibitor known in the art as LY3023414, and a triple combination which also adds fulvestant, and to methods of using the dual and triple combinations to treat patients with certain disorders, such as in patients with breast cancer, in particular patients with advanced or metastatic breast cancer.

Breast cancer is the most common cancer among women worldwide. It is also one of the leading causes of cancer deaths among women (~ 40,000/yr). Locally Advanced Breast Cancer mat is unresectable refers to the most advanced-stage non- metastatic breast tumors, which are generally large tumors, or involve the skin, chest wall, or lymph nodes. Metastatic Breast Cancer (mBC) occurs when the cancer spreads beyond the breast to other parts of the body. In addition to the patients who are initially diagnosed with mBC, nearly 30% of women diagnosed with early breast cancer will eventually develop mBC. Patients diagnosed with mBC face a median survival of 2-4 years, and mBC currently remains incurable.

Abemaciclib (LY2835219), [5-(4-e l-piperaan-l-ylmem^

fluoro-4-(7-fluoro-3-isopropyl-2-memyl-3H-benzdnu

is a CDK inhibitor mat targets the CDK4 and CDK6 cell cycle pathway, with antineoplastic activities. Abemaciclib, mduding salt forms, and methods of making and using mis compound mduding for the treatment of cancer and more preferably, for the treatment of breast cancer are disdosed in WO2010/075074. Abemaddib has the following structure:

using mis compound including for the treatment of cancer and more specifically for the treatment of breast cancer are disclosed in WO2012/097039. Furthermore, this compound is being investigated in clinical trials for advanced metastatic cancer, mesothelioma (as monotherapy or in combination with pemetrexed cisplatin), breast cancer (in combination with fulvestrant), as well as in squamous non-small cell lung cancer (as monotherapy or in combination with necitumum&b), and metastatic castration resistant prostate cancer (in combination with enzalutamide). LY3023414 has the following structure:

pentafluoropenty lsulphiny l)nony 1] oestra- 1 , 3-5(10 triene-3, 17JJ-diol, or ICI 182,780, is a selective estrogen receptor degrader (SERD) disclosed in US 4,659,516. It is indicated for the treatment of hormone receptor positive metastatic breast cancer in postmenopausal women wit disease progression following anti-estrogen therapy. Fulvestrant has the following structure:

Certain preclinical studies investigating selected aspects of the mechanism of action for the aforementioned targets have been described in the art For example, preclinical studies suggest possible synergy in targeting both cell cycle via CDK inhibitors and the PI3K pathway (David-Pfeuty T. et al., Int J Oncol. 2010 Apr,36(4): 873-81). It has been shown that PI3K and mTOR inhibitors cause Gl cell-cycle arrest and downregulation of cyclin Dl and CDKs (Gao N. et al., Am J Physiol Cell Physiol. 2004 Aug; 287(2): C281- 91). PI3K inhibition also dramatically potentiates inhibition of CDK4 and CDK6 in leukemia cell models (Yu C, Cancer Res. 2003 Apr 15 ;63(8): 1822-33). CDK4/6 inhibition has been shown to sensitize PIK3CA mutant breast cancer cell lines to PI3K inhibition where such lines had demonstrated previous ae novo or acquired resistance to PI3K inhibitors (Vora, Sadhna R. et al., "CDK4/6 Inhibitors Sensitize PIK3CA Mutant Breast Cancer to PI3K Inhibitors" Cancer Cell (2014) 26: 136-149.). Although PI3K inhibitors could prevent resistance to CDK4/6 inhibitors, they failed to resensitize cells once resistance had been acquired, and a triple combination of endocrine therapy, CDK4/6, and PI3K inhibition has been shown as more effective man paired

combinations, provoking rapid tumor regressions in a PDX model (Herrera-Abreu MT. et al, Cancer Res. 2016 Apr 15 ;76(8): 2301-13). Certain combinations of CDK4/6 inhibitors with anti-hormonal agents and/or PI3K inhibitors have been reported in the art See WO 2013/006532 and WO 2015/022609.

Broadly applicable therapies for cancer, in particular, for breast cancer, still remain elusive and there exists a need for more and different therapies that may prove to be effective in treating patients with breast cancer, in particular, patients with locally advanced breast cancer or metastatic breast cancer, more particularly, in patients with hormone receptor positive (HR+), human epidermal growth factor receptor 2 (HER2) negative metastatic breast cancer. The present invention discloses methods of treating breast cancer with a combination of abemaciclib and LY3023414 which said combination may also include fulvestrant that may provide new treatment options for patients and may provide an enhanced and/or unexpected beneficial therapeutic effect in some patients over those of the individual agents alone.

According to one aspect of the present invention, there is presented a method of treating breast cancer m a patient, comprising adininistering to the patient an effective amount of abemaciclib, or a pharmaceutically acceptable salt thereof, in combination with an effective amount of LY3023414, or a pharmaceutically acceptable salt thereof.

Preferably the method further comprises administering an effective amount of fulvestrant, or a pharmaceutically acceptable salt thereof. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PK3C mutatatioa More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, mere is presented a kit for the treatment of breast cancer comprising abemaciclib, or a pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof. Preferably the kit also comprises fulvestrant, or a pharmaceutically acceptable salt thereof.

Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PEK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, there is presented a kit for the treatment of breast cancer comprising abemaciclib, or a pharmaceutical by acceptable salt thereof, with one or more pharmaceutically acceptable carriers, diluents, or excipients, and an oral agent including LY3023414, or a pharmaceutically acceptable salt thereof, with one or more pharmaceutically acceptable carriers, diluents, or exdpients. Preferably the kit further comprises fulvestrant, or a pharmaceutically acceptable salt thereof, with one or more pharmaceutically acceptable carriers, diluents, or excipients. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, there is presented a combination comprising abemaciclib, or a pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof, for simultaneous, separate, or sequential use in the treatment of breast cancer. Preferably there is further presented the combination comprising abemaciclib, or a pharmaceutically acceptable salt thereof, LY3023414, or a pharmaceutically acceptable salt thereof, and fulvestrant, or a pharmaceutically acceptable salt thereof, for simultaneous, separate, or sequential use in the treatment of breast cancer. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PK3C mutation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, there is presented abemaciclib, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with LY3023414, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer. Preferably there is further presented abemaciclib, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with LY3023414, or a pharmaceutically acceptable salt thereof, and fulvestrant, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PIK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, mere is presented

LY3023414, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with abemaciclib, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer. Preferably there is further presented LY3023414, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with abemaciclib, or a pharmaceutically acceptable salt thereof, and fulvestrant, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PIK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

According to another aspect of the present invention, there is presented fulvestrant, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with abemaciclib, or a pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PEK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib. The present invention also provides for use of abemaciclib, or a pharmaceutically salt thereof, in the manufacture of a medicament for the treatment of breast cancer wherein abemaciclib, or the salt thereof, is to be administered in simultaneous, separate, or sequential combination with LY3023414, or a pharmaceutically acceptable salt thereof Preferably the present invention further provides for use of abemaciclib, or a

pharmaceutically salt thereof, in the manufacture of a medicament for the treatment of breast cancer wherein abemaciclib, or the salt thereof, is to be administered in

simultaneous, separate, or sequential combination with LY3023414, or a

pharmaceutically acceptable salt thereof, and fulvestrant, or a pharmaceutically acceptable salt thereof. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PIK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

The present invention also provides for use of LY3023414, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for the treatment of breast cancer wherein LY3023414, or the salt thereof, is to be administered in simultaneous, separate, or sequential combination with abemaciclib, or a pharmaceutically salt thereof. Preferably the present invention further provides for use of LY3023414, or a

pharmaceutically acceptable salt thereof, in the manufacture of a medicament for the treatment of breast cancer wherein LY3023414, or the salt thereof, is to be administered in simultaneous, separate, or sequential combination with abemaciclib, or a

pharmaceutically salt thereof, and fulvestrant, or a pharmaceutically acceptable salt thereof. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PIK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbodclib or ribociclib.

The present invention also provides for use of fulvestrant, or a pharmaceutically salt thereof, in the manufacture of a medicament for the treatment of breast cancer wherein fulvestrant, or the salt thereof, is to be administered in simultaneous, separate, or sequential combination with abemaciclib, or a pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof. Preferably, the breast cancer is locally advanced breast cancer or metastatic breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbodclib or ribociclib.

For all of the preceding aspects, the following are preferred dosing. Preferably abemaciclib, or the pharmaceutically salt thereof, is administered at a dose of 50 mg to 200 mg twice a day in a 28-day cycle. Also preferably abemaciclib or the

pharmaceutically salt thereof is administered at a dose of 100 mg to 150 mg twice a day in a 28-day cycle. More preferably, abemaciclib or the pharmaceutically salt thereof is administered at a dose of ISO mg twice a day in a 28-day cycle. Preferably abemaciclib is administered orally. More preferably, abemaciclib is administered by capsule. Also more preferably, abemaciclib is administered by tablet

Preferably fulvestrant, or a pharmaceutically acceptable salt thereof, is administered in a range of about 250 mg to about 500 mg intramuscularly on Days 1 and IS in a first 28-day cycle (Cycle 1), then on Day 1 of a second 28-day cycle (Cycle 2) and for any subsequent 28-day cycle. Preferably fulvestrant, or a pharmaceuticalry acceptable salt thereof, is administered at 2S0 mg intramuscularly on Days 1 and IS of Cycle 1, men on Day 1 of Cycle 2 and for any subsequent 28 -day cycle. Preferably fulvestrant, or a pharmaceutically acceptable salt thereof, is administered at 500 mg intramuscularly on Days 1 and IS of Cycle 1, men on Day 1 of Cycle 2 and for any subsequent 28-day cycle.

Preferably LY3023414 is administered orally. Preferably LY3023414, or a pharmaceutically acceptable salt thereof, is administered at a dose of about 150 mg to about 200 mg twice a day in a 28-day cycle. Preferably LY3023414, or a

pharmaceutically acceptable salt thereof, is administered at a dose of 1 SO mg twice a day in a 28-day cycle. Preferably LY3023414, or a pharmaceutically acceptable salt thereof, is administered at a dose of 200 mg twice a day in a 28-day cycle.

Preferably abemaciclib, or a pharmaceutically acceptable salt thereof, is administered at a dose of ISO mg twice a day in a 28-day cycle, LY3023414, or a pharmaceutically acceptable salt thereof, is administered at a dose of 1 SO mg twice a day in a 28-day cycle, and optionally fulvestrant, or a pharmaceutically acceptable salt thereof, is administered at a dose of 500 mg intramuscularly on Days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and for any subsequent 28-day cycle. Preferably abemaciclib, or a pharmaceutically acceptable salt thereof, is administered at a dose of ISO mg twice a day in a 28-day cycle, LY3023414, or a pharmaceutically acceptable salt thereof, is administered at a dose of 200 mg twice a day in a 28-day cycle, and optionally fulvestrant, or a pharmaceutically acceptable salt thereof, is administered at a dose of 500 mg intramuscularly on Days 1 and IS of Cycle 1, then on Day 1 of Cycle 2 and for any subsequent 28 -day cycle. Preferably abemaciclib is administered at a dose of 200 mg twice a day in a 28-day cycle, LY3023414 is administered at a dose of ISO mg twice a day in a 28-day cycle, and optionally fulvestrant is administered at a dose of 500 mg intramuscularly on Days 1 and IS of Cycle 1, then on Day 1 of Cycle 2 and for any subsequent 28-day cycle. Preferably abemaciclib is administered at a dose of 200 mg twice a day in a 28-day cycle,LY3023414 is administered at a dose of 200 mg twice a day in a 28-day cycle, and optionally fulvestrant, or a pharmaceutically acceptable salt thereof, is administered at a dose of 500 mg intramuscularly on Days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and for any subsequent 28-day cycle.

As used herein, the term "kit" refers to a package comprising at least two separate agents, wherein a first agent is abemaciclib, or a pharmaceutically acceptable salt thereof, and a second agent is LY3023414, or a pharmaceutically acceptable salt thereof, and, optionally a third agent is fulvestrant, or a pharmaceutically acceptable salt thereof. A "kit" may also include instructions to administer all or a portion of these agents to a cancer patient, preferably a breast cancer patient, more preferably, a locally advanced breast cancer patient or a metastatic breast cancer patient, most preferably hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer. More preferably, the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer. More preferably, the patient has a PK3C mutatation. More preferably, the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

As used herein, the terms "treating", "to treat", or "treatment" refers to restraining, slowing, stopping, reducing, shrinking, maintaining stable disease, or reversing the progression or severity of an existing symptom, disorder, condition, or disease.

As used herein, the term "patient" refers to a mammal, preferably a human.

As used herein, the terms "cancer" and "cancerous" refer to or describe the physiological condition in patients that is typically characterized by unregulated cell proliferation. Included in this definition are benign and malignant cancers.

As used herein, the term "effective amount" refers to the amount or dose of abemaciclib, or a pharmaceutically acceptable salt thereof, and the amount or dose of LY3023414, or a pharmaceutically acceptable salt thereof, and, for the triple

combination, the amount or dose of fulvestrant, or a pharmaceutically acceptable salt thereof, which provides an effective response in the patient under diagnosis or treatment

As used herein, the term "effective response" of a patient or a patient's

"responsiveness" to treatment with a combination of agents refers to the clinical or therapeutic benefit imparted to a patient ui^ adrmmslration of abemacicUb, or a pharmaceutically acceptable salt thereof, LY3023414, or a pharmaceutically acceptable salt thereof, and, for the triple combination, fulvestrant, or a pharmaceutically acceptable salt thereof.

As used herein, the term "in combination with" refers to the administration of abemaciclib, or a pharmaceutically acceptable salt thereof, LY3023414, or a

pharmaceutically acceptable salt thereof, and, for the triple combination, fulvestrant, or a pharmaceutically acceptable salt thereof, either simultaneously or sequentially in any order, such as for example, at repeated intervals as during a standard course of treatment for a single cycle or more than one cycle, such that one agent can be administered prior to, at the same time, or subsequent to the administration of the other agent, or any combination thereof. A main advantage of the combination treatments of the invention is the ability of producing marked anti-cancer effects in a patient without causing significant toxicities or adverse events, so that the patient benefits from the combination treatment method overall. The efficacy of the combination treatment of the invention can be measured by various endpoints commonly used in evaluating cancer treatments, including but not limited to, tumor regression, tumor weight or size shrinkage, time to progression, overall survival, progression free survival, overall response rate, duration of response, and quality of life. The therapeutic agents used in the invention may cause inhibition of locally advanced or metastatic spread without shrinkage of the primary tumor, may induce shrinkage of the primary tumor, or may simply exert a tumoristatic effect Because the invention relates to the use of a combination of unique anti-tumor agents, novel approaches to detennining efficacy of any particular combination therapy of the present invention can be optionally employed, including, for example, measurement of plasma or urinary markers of angiogenesis and/or cell cycle activity, tissue-based biomarkers for angiogenesis and/or cell cycle activity, and measurement of response through radiological imaging.

The free base of the compounds is preferred. However, it will be understood by the skilled reader that compounds can react with any of a number of inorganic and organic acids to form pharmaceutically acceptable salts. Such pharmaceutically acceptable salts and common methodology for preparing them are well known in the art. See, e.g., P. Stahl, etal, Handbook of Pharmaceutical Salts: Properties, Selection and Use (VCHA/Wiley-VCH, 2002); L.D. Bighley, etal., Encyclopedia of Pharmaceutical Technology, 453-499 (1995); S.M. Berge, et al., Journal of Pharmaceutical Sciences, 66, 1, (1977). The hydrochloride and mesylate salts are preferred salts for abemaciclib. The mesylate salt is an especially preferred salt for abemaciclib.

The route of administration may be varied in any way, limited by the physical properties of the drugs and the convenience of the patient and the caregiver. Preferably abemaciclib, or a pharmaceutically acceptable salt thereof, is administered orally.

Abemaciclib, or a pharmaceutically acceptable salt thereof, may be formulated into a tablet or capsule. Preferably LY3023414, or a pharmaceuticalry acceptable salt thereof, is administered orally. LY3023414, or a pharmaceuticalry acceptable salt thereof, may be formulated into a tablet or capsule. Preferably fulvestrant, or a pharmaceutically acceptable salt thereof, may be formulated to be administered intramuscularly (EM). For example, fulvestrant may be administered EM into the buttocks slowly (1 to 2 minutes per injection) as two 250-mg injections, one in each buttock; however, for patients with moderate hepatic impairment (defined as Child Pugh Class B), including any patient who develops moderate hepatic impairment during study treatment, fulvestrant 2S0 mg should be administered IM into the buttock slowly (1 to 2 minutes) as one 250-mg injection. Such pharmaceutical compositions and processes for preparing the aformention compositions are well known in the art. (See, e.g., Remington: The Science and Practice of Pharmacy, L.V. Allen, Editor, 22^nd Edition, Pharmaceutical Press, 2012).

This study is focused on evaluating die combined efficacy of abemaciclib and LY3023414 in a mouse xenograft model for human estrogen-receptor positive (ER+), HER- amplified (HER+) breast cancer. In particular, mice implanted with human ST340 xenografts are treated with abemaciclib mesylate, and LY3023414 alone or in combination, whereby bom compounds are given orally (po) once-daily for 35 days. Monotherapy or combination therapy is evaluated using SO mg/kg of abemaciclib mesylate and IS mg/kg of LY3023414. Tumor volume measurements are taken periodically to determine the effects of the various treatments on tumor growth, and periodic body weight measurements are used as a general indicator of tolerabiliry.

Immunocompromised mice between 6-12 weeks of age are housed on irradiated corncob bedding in individual HEPA ventilated cages (Sealsafe® Plus, Techniplast USA) on a 12-liour light-dark cycle at 21-23X and 40-60% liuniidiry. Animals are fed water ad libitum (reverse osmosis, 2 ppm C12) and an irradiated standard rodent diet consisting of 19% protein, 9% fat, and 4% fiber. In addition, the animals receive exogenous estrogen supplementation ad libitum, through the drinking water.

Abemaciclib mesylate is formulated in 1% hydroxyethyl cellulose (HEC) in 25mM phosphate buffer (PB) pH = 2. The compound is formulated on a weekly basis and stored at 4*C. Abemaciclib mesylate is administered by oral gavage once-daily for 35 days at a dose of SO mg/kg. LY3023414 is formulated in 1% HEC/0.25% TWEEN® 8070.05% Antifoam and is administered by oral gavage once-daily for 35 days at a dose of 15 mg/kg. Animals in the combination group are given SO mg/kg of abemaciclib mesylate and IS mg/kg of LY3023414 according to the schedules described above for monotherapy. The vehicle control group is given both vehicles according to the schedules for abemaciclib mesylate and LY3023414, respectively.

Patient-derived xenograft models, ST340, (South Texas Accelerated Research Therapeutics) a luminal B model originating from a ER+/HER2+ tumor are established from viable human tumor tissue or fluid and have been serially passaged in animals a limited number of times to maintain tumor heterogeneity, m subcutaneous models, animals are implanted unilaterally on the flank with tumor fragments harvested from host animals each implanted from a specific passage lot Pre-study tumor volumes are recorded for each experiment beginning approximately one week prior to its estimated start date. Animals are randomized into treatment groups and dosing is initiated (dosing initiation = Day 0) when tumors reached the appropriate tumor volume initiation (TVI) range (12S-22S mm³). The growth of the ST340 model in mice is facilitated by estrogen supplementation provided through the drinking water.

Tumor size and body weight are measured with digital calipers and tumor volume (V) is estimated by using the formula: V = 0.S36L x W2 where L = larger of measured diameter and W = smaller of perpendicular diameter. The tumor volume data are transformed to a log scale to equalize variance across time and treatment groups. The log volume data are analyzed with a two-way repeated measures analysis of variance by time and treatment using the MIXED procedures in SAS software (Version 9.3). The correlation model for the repeated measures is Spatial Power. Treated groups are compared to the control group at each time point The MIXED procedure is also used separately for each treatment group to calculate adjusted means and standard errors at each tune point. Both analyses accounted for the autocorrelation within each animal and the loss of data that occurred when animals with large tumors were removed from the study early. The adjusted means and standard errors are plotted for each treatment group versus time.

Relative changes in tumor volume (% Δ T/C) are calculated using the tumor volume measurements taken at the end of the dosing period (Study Day 35), whereas the baseline tumor volume is the volume recorded on the first day of dosing (Baseline Day = Study Day 0). % Δ T/C values are calculated using the formula % Δ T/C = 100 x Δ T/ Δ C, whereby T = mean tumor volume of the compound treated group, Δ T = mem tumor volume of the compound treated group minus the mean tumor volume on the baseline day, C = mean tumor volume of the control (vehicle) group, and Δ C = mean tumor volume of the control group minus the mean tumor volume on the baseline day. If Δ T was <0, then a tumor regression value was calculated instead of % Δ T/C whereby %Regression = 100 x Δ T/Ticitw such that Tinitial = the grand mean of the tumor volume for all the treatment groups.

Growth inhibition is observed in those instances where the calculated values for % Δ T/C are less than 100% whereby greater inhibition results in smaller % Δ T/C values.

Calculated values of % Δ T/C greater than 100% indicate instances where the average tumor volume of the treated group is larger than the average tumor volume of the vehicle control group. Any negative values for % Δ T/C listed in the table are values for percent regression whereby the average tumor volume for the treated group is less than the tumor volume measured on the baseline day (Day 0). Progressive disease (PD) is defined as an increase in % Δ T/C relative to baseline of >20%; stable disease (SD) is defined by tumor volumes which show any measureable increase in tumor volume relative to baseline which is <20% (0% < SD < 20%); a partial response (PR) is defined by the range of tumor volumes which either show no growth relative to baseline (0%) or have reductions in tumor volume of 80% or less ( 0% > PR > -80%); and a complete response (CR) is defined by reductions in tumor volume greater than 80% (< -80%). The disease control rate (DCR) for each treatment group is the sum of the animals in that group which achieved a CR, a PR or SD (DCR = SD + PR + CR). The response rate (RR) for a treatment group is the sum of the animals within that group which attained either a PR or CR (RR = PR + CR).

Monotherapy with Abemaciclib Mesylate or LY3023414 Treatment of mice bearing ST340 tumors with either 50 mg/kg of abemaciclib mesylate or 15 mg/kg of LY3023414 alone resulted in an inhibition of tumor growth relative to the vehicle control group. In particular, the % Δ T/C that was observed at the end of the dosing period (Day 35) was approximately 48% and 41% for treatments with abemaciclib mesylate and LY3023414, respectively (Table 1). These values of 48% for abemaciclib mesylate (p=.010) and 41% for LY3023414 (p=.002) were statistically significant as compared to the vehicle controls (Table 1). Although growth inhibition relative to the vehicle control groups was observed, almost all the mice treated with either abemaciclib mesylate or LY3023414 alone had evidence of progressive disease (PD). The best response observed to monotherapy was in the group treated with abemaciclib mesylate wherein 1 of 5 (20%) mice achieved stable disease (SD). Combination Therapy with Abernaciclib Mesylate or LY3023414

Combination chemotherapy with both abemaciclib mesylate and LY3023414 improved the antitumor response. In particular, the combined treatment with 50 mg/kg of abemaciclib mesylate and 15 mg/kg of LY3023414 resulted in significant growth inhibition relative to the vehicle control group such mat the % Δ T/C observed at the end of the dosing period (Day 35) was 16% (Table 1). This inhibition of growth was significant when compared with the % Δ T/C of 48% (p=.030) and 41% (p=.014) achieved with abemaciclib mesylate and LY3023414 monotherapy, respectively as well as with the vehicle control group (p<.001). The data also demonstrate the enhanced response associated with combination chemotherapy as compared to the groups receiving monotherapy with either LY3023414 or abemaciclib mesylate. Specifically by the end of the dosing period (Day 35), 3 of 4 (75%) mice had achieved a PR versus 1 of 5 (20%) and 0 of 5 (0%) mice treated alone with abemaciclib mesylate or LY3023414, respectively. Note mat one mouse in the combination group died during the course of treatment on Day 25. Thus there were only 4 mice remaining in this group on the day (Day 35) when this analysis was done.

Claims

WE CLAIM:

1. A method of treating breast cancer in a patient, comprising administering to the patient an effective amount of abemaciclib, or a pharmaceutically acceptable salt thereof, in combination with an effective amount of LY3023414, or a pharmaceutically acceptable salt thereof.

2. The method according to claim 1 further comprising administering an effective amount of fulvestrant, or a pharmaceutically acceptable salt thereof.

3. The method according to claim 1 or claim 2 wherein the breast cancer is locally advanced breast cancer.

4. The method according to claim 1 or claim 2 wherein the breast cancer is metastatic breast cancer.

5. The method according to any one of claims 1-4 wherein the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer.

6. The method according to any one of claims 1-4 wherein the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer.

7. The method according to any one of claims 1-6 wherein the patient has a PK3C mutatatioa

8. The method according to any one of claims 1-7 wherein the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.

9. A combination comprising abemaciclib, or a pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof, for simultaneous, separate, or sequential use in the treatment of breast cancer.

10. Abemaciclib, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with LY3023414, or a

pharmaceutically acceptable salt thereof, in the treatment of breast cancer.

11. LY3023414, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with abemaciclib, or a

pharmaceutically acceptable salt thereof, in the treatment of breast cancer.

12. A combination for use according to claim 9; abemaciclib, or a

pharmaceutically acceptable salt thereof, for use according to claim 10; or LY3023414, or a pharmaceutically acceptable salt thereof for use according to claim 11 ; in simultaneous, separate, or sequential combination with fulvestrant, or a pharmaceutically acceptable salt thereof.

13. Fulvestrant, or a pharmaceutically acceptable salt thereof, for use in simultaneous, separate, or sequential combination with abemaciclib, or a

pharmaceutically acceptable salt thereof, and LY3023414, or a pharmaceutically acceptable salt thereof, in the treatment of breast cancer.

14. The combination, abemaciclib or the salt thereof, LY3023414 or the salt thereof, or fulvestrant or the salt thereof, according to any one of claims 9 -13 wherein the breast cancer is metastatic breast cancer.

15. The combination, abemaciclib or the salt thereof, LY3023414 or the salt thereof, or fulvestrant or the salt thereof, according to any one of claims 9-14 wherein the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 negative breast cancer.

16. The combination, abemaciclib or the salt thereof, LY3023414 or the salt thereof, or fulvestrant or the salt thereof, according to any one of claims 9-14 wherein the breast cancer is hormone receptor positive, human epidermal growth factor receptor 2 positive breast cancer.

17. The combination, abemaciclib or the salt thereof, LY3023414 or the salt thereof, or fulvestrant or the salt thereof, according to any one of claims 9-16 wherein the patient has a PK3C mutation.

18. The combination, abemaciclib or the salt thereof, LY3023414 or the salt thereof, or fulvestrant or the salt thereof, according to any one of claims 9-17 wherein the patient's cancer has progressed on previous CDK4/6 therapies such as palbociclib or ribociclib.