On June 6, 2016 Clovis Oncology (NASDAQ:CLVS) reported updated phase 2 results from Part 1 of the ongoing ARIEL2 study in patients with advanced ovarian cancer as well as the final results of the RUCAPANC study of rucaparib in pancreatic cancer at the 2016 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago (Press release, Clovis Oncology, JUN 6, 2016, View Source;p=RssLanding&cat=news&id=2175294 [SID:1234513036]). Rucaparib is the Company’s oral, potent, small molecule inhibitor of PARP1, PARP2 and PARP3 currently being developed for the treatment of ovarian cancer, specifically in patients with tumors with BRCA mutations and other DNA repair deficiencies beyond BRCA, including those with high genomic loss of heterozygosity (LOH) also known as "BRCA-like."

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"We are pleased to present our mature dataset from Part 1 of the ARIEL2 study for rucaparib in ovarian cancer at ASCO (Free ASCO Whitepaper), which demonstrates its encouraging clinical activity in selected patients and its potential in the treatment of advanced ovarian cancer," said Patrick J. Mahaffy, CEO and President of Clovis Oncology. "We are also encouraged by the results of the RUCAPANC study of rucaparib in advanced pancreatic cancer patients with mutations of BRCA, and look forward to exploring rucaparib in additional tumor types in which mutations in BRCA and other DNA repair deficiencies play a significant role."

Study objectives of the global, two-part single-arm open-label ARIEL2 trial in patients with advanced ovarian cancer include determining rucaparib activity in prospectively defined molecular subgroups through the assessment of progression-free survival (PFS) in patients with tumors that have germline and somatic BRCA mutations, those with a BRCA-like signature (patients whose tumors have other DNA repair deficiencies, including those with high genomic LOH but with normal BRCA genes (BRCAwt/LOHhigh)), and patients whose tumors are biomarker negative (those with low genomic LOH, or BRCAwt/LOHlow). Objective response rate (ORR), safety and pharmacokinetics were also analyzed. Patients in ARIEL2 were treated with the recommended phase 2 dose (RP2D) of 600mg twice daily (BID). ARIEL2 Part 1 was initiated in October 2013 and completed enrollment in 2014. At the data cutoff date of January 18, 2016, 28 of the 204 patients enrolled in ARIEL2 Part 1 remained on study. These patients were required to be platinum-sensitive for enrollment and received a median of one prior treatment regimen and a median of one prior platinum-based chemotherapy regimen. Enrollment continues for ARIEL2 Part 2, which expanded the ARIEL2 study in early 2015 into up to 300 additional patients with recurrent disease after at least three prior lines of chemotherapy. Enrollment into ARIEL2 Part 2 is not limited to platinum-sensitive disease, but also includes patients with platinum-resistant or platinum-refractory disease. Presentation of ARIEL2 Part 2 data will follow at a future medical meeting.

A NGS-based assay developed with Foundation Medicine, Inc. was used to determine the percentage of genomic LOH, mutations in BRCA, and other homologous recombination genes in archival tumor tissue and pretreatment biopsies for patients enrolled in ARIEL2. A prespecified cutoff of ≥14% for LOHhigh was determined through analysis of microarray and survival data for patients in The Cancer Genome Atlas who had ovarian carcinoma and had received platinum-based chemotherapy. A planned post hoc analysis using outcome data from ARIEL2 Part 1 was performed to refine the genomic cutoff. The data for both the prespecified and refined cutoff percentages are presented in today’s poster presentation.

Updated Results of ARIEL2 Part 1
Data presented from the ARIEL2 Part 1 study demonstrated clinical activity in patients with tumors with germline and somatic BRCA mutations as well as those with tumors classified as BRCAwt/LOHhigh.

Using the prespecified ≥14% cutoff, patients in the BRCAmut subgroup demonstrated a 73 percent reduction in the risk of progression, and patients in the BRCAwt/LOHhigh subgroup demonstrated a 38 percent reduction in the risk of progression, both compared to the BRCAwt/LOHlow subgroup (hazard ratio: 0.27 [95% CI: 0.16, 0.44; p<0.001] and hazard ratio: 0.62 [95% CI: 0.42, 0.90; p=0.01], respectively). Median PFS for the BRCAmut, BRCAwt/LOHhigh, and BRCAwt/LOHlow subgroups was 12.8 months, 5.7 months and 5.2 months, respectively.

An analysis of platinum-sensitive patients from ARIEL2 Part 1 identified a refined LOH cutoff of ≥16% that provided further discrimination of PFS, objective response rate and duration of response in patients with LOHhigh and LOHlow tumors who received a median of one prior treatment regimen. Using the refined LOH cutoff of ≥16%, patients in the BRCAmut subgroup demonstrated a 75 percent reduction in the risk of progression, and patients in the BRCAwt/LOHhigh subgroup demonstrated a 49 percent reduction in the risk of progression, both compared to the BRCAwt/LOHlow subgroup (hazard ratio: 0.25 [95% CI: 0.15, 0.42; p<0.001] and hazard ratio: 0.51 [95% CI: 0.34, 0.74; p<0.001], respectively). Median PFS for the BRCAmut, BRCAwt/LOHhigh, and BRCAwt/LOHlow subgroups was 12.8 months, 7.2 months and 5.0 months, respectively.

The confirmed investigator-assessed ORR based on RECIST criteria was significantly higher in the BRCAmut subgroup than in the BRCAwt/LOHlow with the prespecified LOH cutoff. As expected, the most robust clinical responses were observed in patients with tumor (germline and somatic) BRCA mutations: 80 percent (32/40) of BRCAmut patients achieved a response. Responses were observed in both germline and somatic BRCAmut tumors, including 85 percent (17/20) of patients with a gBRCA mutation and 74 percent (14/19) of patients with a sBRCA mutation. One patient with a BRCA mutation was indeterminate for mutation type. In the BRCAwt/LOHhigh subgroup, the ORR was 29 percent (24/82) and 33 percent (23/69) based on the prespecified and refined cutoff, respectively. In the BRCAwt/LOHlow subgroup, the ORR was 10 percent for both the prespecified and refined cutoffs, representing responses in 7 of 70 and 8 of 83 patients, respectively. Median duration of response for the prespecified and refined LOH cutoffs for the BRCAmut and BRCAwt/LOHhigh subgroups were the same at 9.2 months and 10.8 months, respectively, and highly similar for the BRCAwt/LOHlow subgroup at 5.6 months and 5.5 months, respectively.

The most common treatment-emergent AEs reported in ≥20 percent of all patients included nausea (80%), asthenia/fatigue (78%), constipation (46%), vomiting (44%) and dysgeusia (43%). These events were mostly Grade 1/2. The most common Grade 3/4 treatment-emergent AEs were anemia/decreased hemoglobin (21%) and ALT/AST elevations (12%). No treatment-related deaths were reported. Nineteen patients (9%) discontinued treatment because of an adverse event.

These results support the predictive utility of an HRD signature to identify patients with platinum-sensitive ovarian cancer who may benefit from rucaparib treatment. The NGS-based HRD assay will be prospectively applied to assess the utility of a rucaparib treatment-based LOHhigh cutoff in predicting response to rucaparib in the phase 3 ARIEL3 study investigating rucaparib in the maintenance setting in platinum-sensitive ovarian cancer.

Feasibility of Monitoring Response to Rucaparib with ctDNA
A study at the University of Cambridge was conducted to assess TP53 mutant allele fraction (MAF) in circulating tumor DNA (ctDNA) from a subset of 18 patients in ARIEL2 Part 1 and will be presented in a poster session this afternoon. Plasma samples were collected from 18 patients in the ARIEL2 Part 1 study during screening, on day 1 of each cycle, and at the end of rucaparib treatment. The objective was to assess monitoring responses to rucaparib with targeted amplicon deep sequencing (TADS) of ctDNA. Seven of 9 patients with a >50% reduction of TP53 MAF in ctDNA at cycle 2 achieved a RECIST PR; this included 5/6 patients with either a germline or somatic BRCA mutation. No patients with a <50% reduction at cycle 2 (n=5) achieved a RECIST response. TADS detected different types of TP53 mutation in plasma including substitutions (n=12) and indels (n=6) across a wide spectrum of allele fractions (0.01–42.3%) with 100% concordance for TP53 mutation status in matched tumor-plasma samples. ctDNA is a potential biomarker for monitoring responses to the PARP inhibitor rucaparib.

Final Results of RUCAPANC
The open-label phase 2 RUCAPANC study investigated the safety and efficacy of rucaparib in patients with advanced pancreatic cancer and a known deleterious germline or somatic BRCA mutation and final results were presented in a poster session on June 4. A total of 19 patients were enrolled and received one or more doses of rucaparib, with a median of three cycles (range 1-18) of treatment started. The confirmed investigator-assessed ORR based on RECIST criteria was 16%, in which two partial responses (PR) and one complete response (CR) were observed. The disease control rate was 32% for all patients (6/19) and 50% for patients with one prior chemotherapy (3/6). All three patients with a confirmed response received only one prior line of therapy. Common treatment-emergent AEs included nausea (63%) and anemia (47%). These findings are expected to inform future rucaparib study designs in patients with advanced BRCAmut pancreatic cancer.

About Rucaparib Clinical Development
The ARIEL (Assessment of Rucaparib in Ovarian Cancer Trial) program is a novel, integrated translational-clinical program designed to accurately and prospectively identify ovarian cancer patients with tumor genotypes associated with benefit from rucaparib therapy.

ARIEL2 is a two-part single-arm open label study. Part 1 is in platinum-sensitive patients designed to identify pre-specified tumor characteristics that predict sensitivity to rucaparib using DNA sequencing to evaluate each patient’s tumor and updated results are described above. Part 2, also referred to as the ARIEL2 Extension, is enrolling up to 300 patients with advanced ovarian cancer who have received at least three prior chemotherapy regimens and includes platinum-sensitive, -resistant and -refractory patients. It will evaluate clinical response in patients classified into molecularly-defined subgroups, including gBRCA-mutant, sBRCA-mutant and the BRCA-like signature by a prospectively defined genomic signature.
The phase 2 portion of Study 10, the initial dose finding study, enrolled patients with relapsed, high-grade ovarian cancer associated with a deleterious germline BRCA mutation who have received 2-4 prior lines of chemotherapy.
The ARIEL3 pivotal study is a randomized, double-blind study comparing the effects of rucaparib against placebo to evaluate whether rucaparib given as a maintenance therapy to platinum-sensitive patients can extend the period of time for which the disease is controlled after a positive outcome with platinum-based chemotherapy. Patients are randomized to receive either placebo or rucaparib and the primary endpoint of the study is PFS. The primary efficacy analysis will evaluate, in a step-down process, BRCA-mutant patients, all patients with a BRCA-like signature (including BRCA and non-BRCA), and then all patients.
The ARIEL4 confirmatory study is expected to begin during the second half of 2016, and will compare treatment with rucaparib vs chemotherapy in relapsed ovarian cancer patients with BRCA mutations. The primary endpoint of the study is PFS.
In addition to the ARIEL program in ovarian cancer, the Company is exploring rucaparib in other solid tumor types with significant BRCA and BRCA-like populations, including a pivotal prostate cancer study expected to initiate during the second half of 2016.
Multiple combination studies are planned to initiate in the second half of 2016, including with inhibitors of PD-L1.
For more information, please visit www.arielstudy.com.
Subgroup analysis of later-line BRCA-mutant patients from ARIEL2 Parts 1 and 2 and Study 10 will form the basis of rucaparib’s rolling New Drug Application (NDA) to the U.S. FDA. The NDA submission will include platinum-sensitive, -resistant and -refractory patients from ARIEL2 Part 2, in addition to the platinum-sensitive patients from ARIEL2 Part 1 and Study 10.

The NDA submission is expected to complete by the end of Q2 2016, and a European Marketing Authorization Application (MAA) to the European Medicines Agency is planned for Q4 2016. Rucaparib was granted Breakthrough Therapy designation from the U.S. Food and Drug Administration in April 2015.

Presentation Details
The poster presentation, titled "RUCAPANC: An open-label, phase 2 trial of the PARP inhibitor rucaparib in patients (pts) with pancreatic cancer (PC) and a known deleterious germline or somatic BRCA mutation" was presented Saturday by Robert Vonderheide, MD, D. Phil., University of Pennsylvania, Philadelphia, PA during the Poster Session titled "Gastrointestinal (Noncolorectal) Cancer", from 8:00am-11:30am CDT (Abstract 4110; Poster Board #102).

The poster presentation, titled "Refinement of prespecified cutoff for genomic loss of heterozygosity (LOH) in ARIEL2 part 1: A phase II study of rucaparib in patients (pts) with high grade ovarian carcinoma (HGOC)" is being presented today by Robert L. Coleman, MD, The University of Texas MD Anderson Cancer Center, Houston, TX during the Poster Session titled "Gynecologic Cancers" from 1:00pm-4:30pm CDT (Abstract 5540 Poster Board #363).

The poster presentation, titled "Feasibility of monitoring response to the PARP inhibitor rucaparib with targeted deep sequencing of circulating tumor DNA (ctDNA) in women with high grade serous carcinoma on the ARIEL2 trial" is being presented today by Mitch Raponi, D. Phil, Biochemistry and Molecular Genetics, Clovis Oncology on behalf of the author, Anna Piskorz, PhD, Cancer Research UK Cambridge Institute, University of Cambridge during the Poster Session titled "Gynecologic Cancers" from 1:00pm-4:30pm CDT (Abstract 5549 Poster Board #372).

The poster presentations will be available online at View Source as of the time of their scheduled presentation at the meeting.

About Rucaparib
Rucaparib is an oral, potent small molecule inhibitor of PARP1, PARP2 and PARP3 being developed for the treatment of ovarian cancer, specifically in patients with tumors with BRCA mutations and other DNA repair deficiencies beyond BRCA, including those with high genomic loss of heterozygosity (LOH) commonly referred to as "BRCA-like." Clovis is also exploring rucaparib in other solid tumor types with significant BRCA and BRCA-like populations, including prostate, breast and gastroesophageal cancers. Rucaparib was granted Breakthrough Therapy designation by the U.S. FDA in April 2015. Clovis holds worldwide rights for rucaparib.

OnJune 7, 2016 CTI BioPharma Corp. (CTI BioPharma) (NASDAQ and MTA:CTIC) reported long-term safety and efficacy results from the pivotal Phase 3 PERSIST-1 trial evaluating pacritinib versus best available therapy, excluding treatment with JAK2 inhibitors (BAT), in patients with myelofibrosis (Press release, CTI BioPharma, JUN 6, 2016, View Source;p=RssLanding&cat=news&id=2175567 [SID:1234513106]). As previously reported, the PERSIST-1 trial met its primary endpoint in the intent-to-treat population with statistically significant reduction in spleen volume when compared to patients receiving BAT. The results represent an update on the efficacy and safety for all patients regardless of their initial platelet count, including patients with very low platelet counts at study entry, a condition known as severe or life-threatening thrombocytopenia. The most frequently occurring adverse events with pacritinib were gastrointestinal events and incidence decreased over time. For patients crossing over to receive pacritinib treatment (84 percent of BAT patients), less than 5 percent of patients had diarrhea with only one patient experiencing grade 3. Patients in the BAT arm that crossed over to receive pacritinib treatment had a similar rate of events as patients initially randomized to BAT or pacritinib. A planned analysis of the study up to 72 weeks demonstrated treatment with pacritinib led to durable reductions in spleen volume and symptom burden, two key measures of disease control, in patients with myelofibrosis, including patients with low platelets at baseline (less than 50,000 per microliter and less than 100,000 per microliter). Patients who crossed over to pacritinib from BAT experienced similar reductions in spleen volume and symptom burden as patients initially randomized to pacritinib, including patients with low platelets. Pacritinib is an investigational oral kinase inhibitor with specificity for JAK2, FLT3, IRAK1 and CSF1R, which are kinases found to be involved in the growth and spread of myelofibrosis and other blood-related cancers.

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"From the time a patient is diagnosed with myelofibrosis, the incidence of disease-related thrombocytopenia increases with time," stated Claire Harrison, M.D., Consultant Hematologist, Guy’s and St. Thomas’ NHS Foundation Trust, Guy’s Hospital, London, United Kingdom and one of the principal investigators for PERSIST-1. "Patients with thrombocytopenia have significantly greater symptom burden, distinct clinical characteristics and shorter overall survival. There is currently a significant unmet need for patients with myelofibrosis who are unable to tolerate or control their disease on other treatments due to low platelet counts.

Dr. Harrison added, "It is encouraging to see that patients with baseline thrombocytopenia who were treated with pacritinib, had stable mean platelet counts and hemoglobin levels through the end of treatment, and that some patients with very low platelets increased their platelet counts while receiving pacritinib treatment. In this intermediate- to high-risk patient group, pacritinib was generally well tolerated."

Myelofibrosis is a rare, but serious and life-threatening chronic leukemia that disrupts the normal production of blood cells and results in scarring of the bone marrow, limiting the ability to produce new blood cells and prompting the spleen and other organs to take over this function. The disease often leads to an enlarged spleen and lower than normal counts of blood cells – including red blood cells and platelets, which are essential for blood clotting. Frequent causes of death among patients with myelofibrosis include leukemic transformation (31 percent), disease progression (18 percent), and thrombosis and cardiovascular complications (13 percent) 1.

Below are highlights presented at the 52nd Annual Meeting of the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) being held June 3–June 7, 2016 in Chicago, Ill. The poster presentations are available at www.ctibiopharma.com.

Highlights of Data Presented

Mesa, R, et al. Pacritinib (PAC) vs. best available therapy (BAT) in myelofibrosis (MF): 72 week follow-up of the phase III PERSIST-1 trial. Abstract #7065
In this poster, an update on efficacy and safety of the PERSIST-1 clinical trial up to Week 72 is provided for all patients in the study (pacritinib n=220; BAT n=107), regardless of platelet count. Ninety patients (84 percent) randomized to BAT crossed over to receive pacritinib at a median of 27.2 weeks.

Responses to pacritinib were durable and rates of 35 percent or greater spleen volume reduction (SVR) were maintained from Weeks 24 to 72 (25 percent vs. 24 percent). Patients who crossed over to receive pacritinib achieved similar responses to those receiving initial treatment with pacritinib. Overall survival, although not a primary or secondary endpoint of the trial, did not show a statistically significant difference between the pacritinib and BAT arms. This was primarily due to an imbalance between the two arms, with higher risk patients in the pacritinib arm vs. BAT. The result was potentially confounded by a high percentage of patients who crossed over at Week 24 to receive pacritinib therapy. Pacritinib-treated patients who achieved SVR greater or equal to 20 percent had statistically significant longer overall survival vs. patients who did not achieve SVR at this level.

The most frequently occurring adverse events with pacritinib were gastrointestinal events and the incidence decreased over time. Incidence of grade 3/4 treatment-emergent diarrhea with initial pacritinib treatment was highest in Weeks 1-8 (3 percent) and decreased in Weeks 8-16 (1.4 percent), Weeks 16-24 (1.5 percent) and in the final period analyzed, Weeks 64-72 (0.9 percent). Up to 24 weeks, prior to the majority of patients in the BAT arm crossing over, there was no statistically significant difference in the incidence of cardiac and bleeding adverse events between the pacritinib and BAT arms; following crossover to pacritinib, BAT patients had a similar rate of all grades of adverse events. The incidence of all grade cardiac AEs was similar between pacritinib and BAT arms between Weeks 1 and 24; incidence of cardiac AEs was greater for pacritinib between Weeks 24 and 72 vs. BAT, but was low overall (5 percent or less at any time). Among all patients, incidence of grade 3/4 bleeding events was 3 percent or less during any 8-week time interval.

Harrison, C, et al. Pacritinib (PAC) vs. best available therapy (BAT) in myelofibrosis (MF): Outcomes in patients (pts) with baseline (BL) thrombocytopenia. Abstract #7011
This analysis examines outcomes up to 72 weeks among patients in the PERSIST-1 trial with baseline platelets less than 100,000 per microliter treated with pacritinib vs. BAT (pacritinib, n=72; BAT, n=34). For patients receiving pacritinib, a median duration of spleen volume reduction (SVR) of 35 percent or greater was 48 weeks for patients with baseline platelets less than 50,000 per microliter and 57 weeks for patients with baseline platelets less than 100,000 per microliter. For BAT-treated patients who crossed over to receive pacritinib before or after Week 24, duration of SVR was 73 weeks for patients with baseline platelets less than 50,000 per microliter and 46 weeks for patients with baseline platelets less than 100,000 per microliter. At Week 36, 46 percent (6/13) of evaluable pacritinib-treated patients with baseline platelets less than 50,000 per microliter and 48 percent (12/28) of evaluable pacritinib-treated patients with baseline platelets less than 100,000 per microliter achieved 50 percent or greater reduction in Total Symptom Score (TSS). This is an increase from 32 percent and 42 percent, respectively, at Week 24.

Patients treated with pacritinib had stable mean platelet counts and hemoglobin levels through Week 72 and increased platelet counts in patients with platelets less than 50,000 per microliter. At 24 weeks, bleeding events occurred at a similar rate in pacritinib-and BAT-treated patients; following crossover to pacritinib, BAT patients had a similar rate of events. Among patients with baseline thrombocytopenia treated with pacritinib, mean hemoglobin levels remained stable through Week 72. Due to BAT crossover to pacritinib at Week 24, there were no evaluable patients with baseline thrombocytopenia in the BAT arm beyond Week 36. These data suggest pacritinib treatment led to durable reductions in spleen volume and symptom burden.

Harrison, C, et al. Outcomes in patients with myelofibrosis and RBC-transfusion dependence in the phase III PERSIST-1 study of pacritinib vs. best available therapy. Abstract #7066
In this poster, pacritinib-treated patients demonstrated clinically meaningful reductions in spleen volume independent of RBC-transfusion independence (RBC-TI). Among pacritinib-treated patients, 16 percent (36/220) were RBC-transfusion dependent (RBC-TD) at baseline. Eighteen (18) patients were RBC-TD at the time of crossover.

Twenty-two percent (12/54) of RBC-TD patients treated with pacritinib either from study start or after crossover achieved RBC-TI during the course of the study. During the course of the study, 25 percent (9/36) of RBC-TD patients treated with pacritinib at the start of the study achieved RBC-TI vs. 0 percent (0/16) patients treated with BAT (p=0.043). Seventeen percent (3/18 patients) of RBC-TD patients at the time of crossover achieved RBC-TI during the crossover period. Pacritinib treatment was associated with improved patient outcomes for those with baseline RBC-TD.

Mesa, R, et al. Pacritinib (PAC) vs. best available therapy (BAT) in myelofibrosis (MF): Long-term follow-up of patient-reported outcomes (PROs) in the phase III PERSIST-1 trial. Abstract #7067
Patient Reported Outcomes (PRO) data at 24 weeks was previously reported and the poster presented today provided an update at Week 48. The Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) is a PRO assessment tool designed to measure myelofibrosis-related symptom burden resulting in a TSS based on how the patient feels or functions in relation to six common symptoms. The proportion of patients achieving a TSS reduction of 50 percent or greater improved from Weeks 24 to 48 and was greater than observed with BAT showing that reduction in symptoms continued to increase over time. In patients who crossed over from BAT to pacritinib, reductions in TSS improved from Week 24 to Week 36. Mean percentage reductions in common symptoms measured in both MPN-SAF versions at Week 48 were greater than those observed at Week 24 among patients treated with pacritinib.

About PERSIST-1

PERSIST-1 is a randomized (2:1), controlled Phase 3 registration-directed trial comparing the efficacy and safety of pacritinib to BAT – which included a broad range of currently utilized treatments – in 327 patients with myelofibrosis (primary myelofibrosis, post-polycythemia vera myelofibrosis or post-essential thrombocythemia myelofibrosis), regardless of the patients’ platelet counts. As previously reported, the trial met its primary endpoint of spleen volume reduction (35 percent or greater from baseline to Week 24 by MRI/CT scan) in the intent-to-treat population (ITT). These results included patients with severe or life-threatening thrombocytopenia. At study entry, 62 percent of patients had primary myelofibrosis; 46 percent of patients were thrombocytopenic; 32 percent of patients had baseline platelet counts less than 100,000 per microliter; and 16 percent of patients had platelet counts less than 50,000 per microliter; normal platelet counts range from 150,000 to 450,000 per microliter. The design of PERSIST-1 allowed for patients on the BAT arm to crossover and receive treatment with pacritinib if their disease progresses or after they achieve the 24-week measurement endpoint. Although crossover design of clinical trials may confound evaluation of survival, which is a tertiary endpoint of PERSIST-1, such designs are frequently used in cancer studies. The median duration of treatment was 16.2 months in patients treated with pacritinib, compared to 5.9 months in patients treated with BAT. The majority of patients (84 percent) on the BAT arm eventually crossed over to receive pacritinib therapy.

About Pacritinib

Pacritinib is an investigational oral kinase inhibitor with specificity for JAK2, FLT3, IRAK1 and CSF1R. In August 2014, pacritinib was granted Fast Track designation by the FDA for the treatment of intermediate and high risk myelofibrosis including, but not limited to, patients with disease-related thrombocytopenia (low platelet counts); patients experiencing treatment-emergent thrombocytopenia on other JAK2 inhibitor therapy; or patients who are intolerant of, or whose symptoms are not well controlled (sub-optimally managed) on other JAK2 therapy. Clinical studies for pacritinib are currently subject to a full clinical hold issued by the U.S. Food and Drug Administration in February 2016. A second Phase 3 study, known as PERSIST-2, is evaluating pacritinib in a subset of patients with myelofibrosis whose platelet counts are 100,000 per microliter or less. Although not all patients enrolled reached the 24-week endpoint prior to the full clinical hold on pacritinib, approximately two thirds of the enrolled patients reached or exceeded the 24-week endpoint evaluation. Therefore, these patients will contribute to the evaluation of the study endpoints. Based on the assumptions of the design, CTI BioPharma believes there is sufficient power to reach statistical significance of the primary objectives. Top-line results from the PERSIST-2 Phase 3 trial of pacritinib are expected in the third quarter of 2016.

CTI BioPharma and Baxalta Incorporated (now part of Shire plc) are parties to a worldwide license agreement to develop and commercialize pacritinib. CTI BioPharma and Baxalta will jointly commercialize pacritinib in the U.S. while Baxalta has exclusive commercialization rights for all indications outside the U.S.

About Myelofibrosis and Myeloproliferative Neoplasms

Myelofibrosis is one of three main types of myeloproliferative neoplasms (MPN), which are a closely related group of hematological blood cancers. The three main types of MPNs are myelofibrosis, polycethemia vera and essential thrombocythemia.2

Myelofibrosis is a serious and life-threatening bone marrow disorder caused by the accumulation of malignant bone marrow cells that triggers an inflammatory response and scars the bone marrow. The replacement of bone marrow with scar tissue limits its ability to produce red blood cells, prompting the spleen and liver to take over this function. Symptoms that arise from this disease include enlargement of the spleen, anemia, extreme fatigue, and pain.

The estimated prevalence of MPNs suggest there are approximately 300,000 people living with the disease in the U.S., of which myelofibrosis accounts for approximately 18,000 patients.3 In Europe, there is a wide variation of prevalence observed across data sources. Myelofibrosis has a median age of 64 at the time of diagnosis3 and is a progressive disease with approximately 20 percent of patients eventually developing AML.4 The median survival for high-risk myelofibrosis patients is less than one and a half years, while the median survival for patients with myelofibrosis overall is approximately six years.5

On June 06, 2016 Cyclacel Pharmaceuticals, Inc. (NASDAQ:CYCC) (NASDAQ:CYCCP) (Cyclacel or the Company), reported updated Phase 1 data from its DNA damage response program evaluating a combination regimen of two Cyclacel product candidates, seliciclib, a cyclin dependent kinase (CDK) inhibitor, and sapacitabine, a nucleoside analogue (Press release, Cyclacel, JUN 6, 2016, View Source [SID:1234513037]). The regimen was orally-administered as sequential (Part 1) or concomitant (Part 2) treatment to 67 heavily-pretreated patients with advanced solid tumors. Antitumor activity was demonstrated in a subgroup of 45 patients with breast, ovarian and pancreatic cancers who tested positive for BRCA mutations (44 germline and 1 sporadic) with a 35.6% disease control rate (1 CR, 5 PR and 10 SD). Treatment durations in responders ranged between 16 and over 240 weeks. No CR or PR was observed in BRCA negative patients. Data were presented at an oral presentation at the 2016 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago.

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"We are encouraged by the durable responses and stable disease seen with the seliciclib and sapacitabine combination in patients with BRCA mutations, in particular because most were heavily pretreated and many are able to remain on study for extended periods," said Sara M. Tolaney, M.D., M.P.H., Associate Director, Clinical Research, Breast Oncology, Dana-Farber Cancer Institute, Boston. "Our findings from Parts 1 and 2 of the study have shown that the orally-administered regimen is well tolerated with manageable toxicities. Based on the results, we believe that further clinical evaluation of this combination regimen is warranted. A Part 3 extension of the study is currently enrolling advanced breast cancer patients with BRCA mutations."

"The findings reported in Dr. Tolaney’s presentation show that the combination treatment of seliciclib and sapacitabine is active and tolerable," said Judy Chiao, M.D., Vice President, Clinical Development and Regulatory Affairs of Cyclacel. "This clinical observation may be directly related to the drugs interference with the capacity of BRCA-mutated cancer cells to repair and survive sapacitabine-induced breaks in their DNA. If these preliminary findings are confirmed by further data, this regimen may provide an important treatment option for patients with BRCA-mutated cancers."

"The ASCO (Free ASCO Whitepaper) data build on earlier data from our DNA damage response program highlighted by the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting Program Committee in a 2013 press conference," said Spiro Rombotis, President and Chief Executive Officer of Cyclacel. "The updated data support and extend clinical evidence of efficacy with different schedules of the combination in this patient population. We are encouraged with the durability of responses and stable disease, with ongoing responding patients achieving treatment durations exceeding 1 and 4.5 years respectively. We look forward to reporting data from the ongoing Part 3 extension in BRCA positive patients with breast cancer and increasing our understanding of the potential benefits of this differentiated treatment strategy in a targeted patient population with significant unmet medical need."

Results

The trial is a dose escalation study conducted in patients with advanced and incurable solid tumors. The orally-administered regimen consists of sapacitabine administered twice daily for 7 days sequentially followed by seliciclib twice daily for 3 days over a 21 day cycle (Part 1, n=38); and sapacitabine dosed each morning followed by seliciclib each evening, each once daily for 5 days per week for 2 weeks of a 28 day cycle (Part 2, n=29). The primary objective of the trial is to determine the maximum tolerated dose with a secondary objective of antitumor activity of the combination. Sixty-seven patients have been treated in Parts 1 and 2 of the study, of which 44 were found to carry BRCA mutations and one a sporadic BRCA mutation.

Best Responses

PART 1 PART 2
BRCA carriers Others BRCA carriers Others
(n=16) (n=22) (n= 28) (n=1)
CR 1 - - -
PR 3 - 2 -
SD 2 6 7 1*
ORR (CR/PR) 25 % 0 % 7 % 0 %
Disease Control (CR/PR/SD) 6 (37.5%) 6 (27.3%) 9 (32.1%) 1 (100.0 %)

* One patient had a sporadic BRCA mutation. CR=complete response, PR=partial response, SD=stable disease.

One CR and five PR were observed in BRCA mutation carriers with breast, ovarian and pancreatic cancers. Treatment durations for the 3 breast/ovarian cancer responders in Part 1 are 54, 93, over 240 weeks and the one breast cancer responder in Part 2 over 76 weeks respectively. Treatment durations for the two pancreatic cancer responders, one each in Parts 1 and 2, are 21 and 16 weeks respectively. Responders included patients who underwent prior treatment with PARP inhibitors and PARP naïve patients. SD was observed in 9 BRCA mutation carriers and 1 sporadic BRCA positive patient with treatment durations ranging from 16 to 88 weeks.

Overall in BRCA positive patients (Parts 1 and 2, n=45), disease control rate is 35.6% and overall response rate (ORR) is 11% (Part 1 ORR 25% and Part 2 7%). The difference in Part 1 and Part 2 ORRs may suggest that the seliciclib dose in the Part 2 schedule may be too low for enhancing the activity of sapacitabine.

Pharmacodynamic effects of the seliciclib and sapacitabine combination were observed in skin biopsies. Part 1 biopsies following treatment showed a 2.3-fold increase in DNA damage induced by sapacitabine, as measured by gamma-H2AX immunohistochemistry. Additional DNA damage occurred after treatment with seliciclib with a 0.58-fold further increase in gamma-H2AX staining.

In Part 1 recommended Phase 2 doses (RP2D) are: sapacitabine 50 mg b.i.d./seliciclib 800 mg b.i.d. Most frequent grade 3/4 adverse events were neutropenia (16%) and elevation in AST (16%). In Part 2 RP2D are: sapacitabine 250 mg q.d./seliciclib 200 mg q.d. Most frequent grade 3/4 adverse events were neutropenia (28%) and elevation in AST (10%). Dose limiting toxicities were reversible elevations in transaminase and bilirubin, neutropenia or febrile neutropenia and pneumonia.

Abstract: 2503
Title: Phase I study of sapacitabine and seliciclib in patients with advanced solid tumors
Date/Time: June 6, 2016 9:00 a.m. — 9:12 a.m. CDT
Location: E354b
Session Title: Developmental Therapeutics—Clinical Pharmacology and Experimental Therapeutics
Authors: SM Tolaney1, J Hilton1, JM Cleary1, L Gandhi1, EL Kwak1, JW Clark1, A Wolanski1, T Bell1, SJ Rodig3, JH Chiao2, D Blake2, G Shapiro1
1Dana-Farber Cancer Institute, Boston, MA; Massachusetts General Hospital Cancer Center, Boston, MA; 2 Cyclacel Ltd, Dundee, United Kingdom; 3 Brigham and Women’s Hospital, Boston, MA.

The abstract can be accessed through the ASCO (Free ASCO Whitepaper) website, View Source

About sapacitabine

Sapacitabine is an oral nucleoside analogue prodrug whose metabolite, CNDAC, generates single-strand DNA breaks (SSB), either leading to arrest of the cell cycle at G2 phase or development of double-strand DNA breaks (DSB). CNDAC-induced DSB repair is dependent on homologous recombination (HR). BRCA mutations in cancer cells are a cause of HR deficiency, making them susceptible to cell death induced by sapacitabine. Sapacitabine is the subject of SEAMLESS, a Phase 3 trial, which has completed enrollment and is being conducted under an SPA with the U.S. Food and Drug Administration (FDA) as front-line treatment for acute myeloid leukemia (AML) in the elderly. Sapacitabine has been evaluated to date in over 1000 patients including randomized Phase 2 and 3 trials in patients with hematological malignancies and previously treated solid tumors, including lung cancer.

About seliciclib

Seliciclib is an orally-available CDK inhibitor molecule that selectively inhibits enzyme targets, CDK2 and CDK9, which are central to the process of cell growth, survival and cell cycle control. Seliciclib treatment has been reported to inhibit the two major DNA double-strand break (DSB) repair pathways, homologous recombination (HR) and non-homologous end joining (NHEJ), by reducing expression of components of each pathway. It may potentiate the activity of sapacitabine by compromising HR protein expression and activation or by potentiating apoptosis following sapacitabine-induced DNA damage. Seliciclib has been evaluated to date in approximately 450 patients including randomized Phase 2 trials in patients with previously treated lung cancer and nasopharyngeal cancer.

On June 6, 2016 Merrimack Pharmaceuticals, Inc. (Nasdaq: MACK) reported results from the final analysis of the Phase 1 study of MM-151, a novel investigational oligoclonal epidermal growth factor receptor (EGFR) inhibitor, in patients with refractory solid tumors (Press release, Merrimack, JUN 6, 2016, View Source [SID:1234513061]). These results were presented at a Poster Discussion Session at the 2016 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago.

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Data from the Phase 1 study show positive clinical activity across multiple solid tumor types in a heavily pretreated patient population. Twenty-one percent of evaluable patients in the metastatic colorectal cancer (CRC) cohort achieved an objective response and 54 percent of patients showed a decrease in tumor size. A median progression-free survival (PFS) of four months was also observed within the CRC cohort. MM-151 also exhibited positive clinical activity in both EGFR-treatment refractory and EGFR-treatment naïve populations. These preliminary data support the potential for broad clinical effect, and demonstrate an acceptable safety profile consistent with existing EGFR therapies.

"We are excited to present the final analysis of the Phase 1 data of MM-151, Merrimack’s novel oligoclonal EGFR-inhibitor," said J. Marc Pipas, M.D., Senior Medical Director at Merrimack. "The promising preliminary Phase 1 data highlights MM-151’s ability to impair EGFR-driven signaling and overcome resistance, particularly in colorectal cancer patients. We are encouraged by these results given the unmet needs in this patient population, and we look forward to further evaluating this investigational therapy’s potential to address this challenging disease."

CRC is the third most common cancer and is the second leading cause of cancer death in the United States. An estimated 144,000 new cases are expected to be diagnosed in 2016. The five-year survival rate for metastatic CRC is estimated at 11 percent.i The two most recent approved drugs for late stage metastatic CRC demonstrated objective response rates of less than two percent and PFS below two months in their clinical studies, while demonstrating an overall survival benefit versus best supportive care (no drug treatment)ii iii.

Methodology and Results

This study evaluated MM-151 as a monotherapy and in combination with irinotecan. An expansion cohort was enrolled to evaluate clinical activity in EGFR-refractory metastatic CRC patients. Subset analyses and additional biomarker evaluations were performed in EGFR-driven indications. A total of 111 patients were treated with escalating dose levels; 87 patients on monotherapy and 24 patients receiving MM-151 in combination with irinotecan. The most common tumor types were CRC (45 [41%]), head and neck cancers (14 [13%]) and non-small cell lung cancer (11 [10%]).

Safety of MM-151

MM-151 demonstrated a comparable safety profile to approved EGFR inhibitors as a monotherapy and in combination with irinotecan.
Apart from infusion reactions, which occurred at decreasing frequency and severity as the dosing schedule was modified over the course of the study, the most common adverse events reported were rash, hypomagnesemia, fatigue and diarrhea in the monotherapy cohorts. These adverse events were expected and consistent with EGFR inhibition class toxicities.
Results

Preliminary indications of clinical activity with MM-151, across both the EGFR-refractory and naïve populations, suggest there is potential for broad effect.
Biomarker profiling suggests MM-151 may overcome mechanisms of resistance.
Preliminary data in the CRC subset show 54 percent of evaluable patients had a reduction in tumors. Forty-five percent (13/29) of patients in the CRC subset achieved stable disease or partial response at three cycles of treatment and 17 percent (5/29) achieved a partial response, with highly durable responses and disease control.
Preliminary biomarker analysis of blood samples ("liquid biopsies") following MM-151 treatment show low occurrence of acquired KRAS/NRAS/BRAF mutations in the CRC cohort and no occurrence of acquired EGFR extracellular domain mutations, which have been reported to mediate resistance to cetuximab and panitumumab.
A median PFS of four months was observed in the CRC cohort.
Observations in exploratory biomarker analyses are consistent with the multiple mechanisms of action that have been previously described for MM-151 in preclinical studies, including EGFR downregulation, expression of high-affinity EGFR ligands across indications (including refractory metastatic CRC) and activity in tumors expressing EGFR and downstream mutations.
Further clinical evaluation is underway.
About MM-151

Merrimack used its systems biology approach to engineer MM-151, an oligoclonal therapeutic that is a mixture of three fully human monoclonal antibodies designed to bind and inhibit signaling of EGFR. EGFR-mediated signaling promotes the growth and survival of cancer cells and is recognized as an important drug target in several types of cancer, including colon, lung, breast, pancreatic and head and neck cancers. The use of three antibodies maximizes receptor inhibition, and provides mechanisms to overcome resistance to EGFR-targeted therapies. MM-151 is also being evaluated in two other Phase 1 studies; one in combination with the ONIVYDE (irinotecan liposome injection) regimen for metastatic CRC, and another in a first-of-its-kind, multi-arm basket study in combination with three other novel agents, two of which are from Merrimack’s oncology pipeline. Merrimack initiated these studies in May.

On June 06, 2016 Calithera Biosciences, Inc. (Nasdaq:CALA), a clinical stage biotechnology company focused on the development of novel cancer therapeutics, reported that clinical data from its lead product candidate CB-839, a first-in-class glutaminase inhibitor, was presented at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting (ASCO) (Free ASCO Whitepaper), in Chicago, Illinois (Press release, Calithera Biosciences, JUN 6, 2016, View Source;p=RssLanding&cat=news&id=2175227 [SID:1234513016]). The data demonstrated the clinical activity, tolerability and unique mechanism of action of CB-839 in patients with renal cell carcinoma and triple negative breast cancer (TNBC).

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"CB-839 is the first tumor metabolism drug to target a pathway that starves cancer cells by directly depriving them of a key nutrient. The combination data presented at ASCO (Free ASCO Whitepaper) demonstrates that CB-839 can safely be added to standard of care therapeutics to treat solid tumors with the potential to improve clinical outcomes," said Susan Molineaux, PhD, President and Chief Executive Officer of Calithera.

CB-839 in Renal Cell Carcinoma

Dr. Funda Meric-Bernstam from MD Anderson Cancer Center will present a poster titled, "Phase I study of CB-839, a small molecule inhibitor of glutaminase, alone and in combination with everolimus in patients with renal cell carcinoma," (Abstract #4568). As of May 23, 2016, thirty-five renal cell carcinoma patients had been treated, including ten in combination with 10 mg daily everolimus, and twenty-five patients treated with CB-839 dosed as a monotherapy. In the combination group, the overall disease control rate was 80%, including one partial response; among eight clear cell and papillary patients, the disease control rate was 100%. The median time on study for these patients is currently 6.5+ months, exceeding the expected progression free survival of everolimus alone in this population. Time on treatment is currently equal to, or greater than the time on prior therapy for most patients, and seven of eight patients remain on study. The combination of CB-839 and everolimus has been well tolerated to date. There was one case of dose-limiting, grade 3 pruitic rash at the 400 mg dose level, which led to a reduction in the dose of everolimus for that patient. On the basis of this efficacy data, the company plans to continue development in combination therapy for renal cell carcinoma.

Among 21 efficacy evaluable patients treated as a monotherapy, 52% experienced stable disease or better, including one partial response. The monotherapy cohort represents an update from the data presented November 8, 2015 at the American Association of Cancer Research-NCI-EORTC conference.

CB-839 in Triple Negative Breast Cancer

Dr. Angela DeMichele from the University of Pennsylvania presented a poster titled, "Phase I study of CB-839, a small molecule inhibitor of glutaminase in combination with paclitaxel in patients with triple negative breast cancer," (Abstract #1011). The abstract was also selected for a poster discussion presentation on Sunday, June 5, 2016. Eligible patients include locally advanced/metastatic TNBC, refractory disease, with prior paclitaxel allowed. As of May 23, 2016, fifteen triple negative breast cancer patients had been treated with doses of CB-839 of 400, 600 or 800 mg bid in combination with 80 mg/m2 IV paclitaxel, weekly, three weeks out of four. The majority of patients had received at least three prior lines of therapy. Six patients received five or more prior therapies in the advanced/metastatic setting. Most patients had received prior taxanes in either the neo-adjuvant (n=7) or metastatic (n=5) setting. Among patients treated with CB-839 doses of at least 600 mg bid (n=8), there were 3 partial responses (38%) and disease control (response or stable disease) in 7 patients (88%). Two of the partial responses were observed in patients that were refractory to paclitaxel in a prior course of therapy. The combination of CB-839 and paclitaxel has been well tolerated to date, with adverse events that have been easily manageable and reversible, including several paclitaxel related toxicities. There was one case of dose-limiting, recurrent grade 3 neutropenia at the 400 mg dose level, which led to a reduction in the dose of paclitaxel for that patient.

Investor Event and Webcast

Calithera will host a conference call and webcast on Monday June 6, 2016, at 6:30 p.m. CT to review the clinical data presented at ASCO (Free ASCO Whitepaper) from the ongoing Phase I study of CB-839. The live audio webcast can be accessed via the Investor section of the Company’s website at www.calithera.com. The conference call can be accessed by dialing (855) 783-2599 (domestic) or (631) 485-4877 (international) and refer to conference ID 23768811. Please log in approximately 5-10 minutes before the event to ensure a timely connection. The archived webcast will remain available for 30 days following the call.