On December 12, 2017 Cyclacel Pharmaceuticals, Inc. (NASDAQ:CYCC) (NASDAQ:CYCCP) "Cyclacel" or the "Company"), a biopharmaceutical company developing oral therapies that target various phases of cell cycle control for the treatment of cancer and other serious disorders, reported results from the Company’s Phase 3 SEAMLESS study (Press release, Cyclacel, DEC 12, 2017, View Source [SID1234522578]). Cyclacel had previously announced top-line results from its Phase 3 SEAMLESS study in February 2017. The study enrolled elderly patients with newly diagnosed acute myeloid leukemia (AML) and compared alternating cycles of decitabine and sapacitabine versus decitabine. Data were reported at an oral presentation on Monday, December 11, at 6:45 PM EST at the 59th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting in Atlanta, Georgia.
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"Although the study did not reach its primary endpoint of superiority in survival, we are encouraged by the higher complete remission rate on the sapacitabine-decitabine arm, especially in the subgroup with low white blood cell count; additional analysis of the data should be pursued," said Hagop Kantarjian, M.D., Professor and Chair, Department of Leukemia, The University of Texas MD Anderson Cancer Center, and chair of the study.
"We are pleased to report detailed results of the SEAMLESS study, which as previously announced, did not reach its primary endpoint," said Spiro Rombotis, President and Chief Executive Officer of Cyclacel. "We believe that the subgroup results have defined a patient population for whom the decitabine-sapacitabine regimen may represent an improvement over low intensity treatment by decitabine alone. We plan to discuss the data, the statistical robustness of the subgroup results and the optimal baseline peripheral white blood cell (WBC) cutpoint with European and US regulatory authorities and will provide updates as appropriate. We are grateful to the patients, their families and the investigators for their contributions to this large study. In parallel, we are progressing our other clinical programs in transcriptional regulation with CYC065 and DNA damage response with sapacitabine-seliciclib in biomarker-selected patients with solid tumors, such as those with BRCA mutations or resistance to existing cancer therapies."
Study Design & Intent-to-Treat Results
The randomized, open label, Phase 3 SEAMLESS study enrolled 482 patients, aged 70 years or older, with newly diagnosed AML who were not candidates for or refused intensive therapy at 110 US and EU sites. Patients were stratified by WBC, antecedent hematologic disorder (AHD), and marrow blasts, and randomized 1:1 to receive either intravenous decitabine administered in alternating cycles with oral sapacitabine versus intravenous decitabine alone.
The trial did not meet its primary endpoint of demonstrating statistically significant improvement in overall survival. A higher complete remission (CR) rate, a secondary endpoint, was observed on the decitabine-sapacitabine arm (17% versus 11%). Other endpoints and safety were similar between the arms.
Prespecified Subgroup Analysis
Baseline WBC
In the less than 10,000 WBC subgroup (n=319) a trend towards improved overall survival (median 8.0 versus 5.8 months, HR=0.84 [0.66, 1.06], p=0.14) favoring decitabine-sapacitabine and a significantly higher CR rate (21.0% versus 8.6%, p=0.0017) was achieved on decitabine-sapacitabine.
In the 10,000 or more WBC subgroup (n=163) significantly better overall survival (median 3.8 versus 5.5 months, HR=1.57 [1.12, 2.19], p=0.007) was observed on decitabine. A trend in CR rate (8.3% versus 15.2%, p=0.18) favoring decitabine was observed but it did not reach statistical significance.
Prior AHD
In the subgroup with prior AHD (n=136) a significantly higher CR rate (16.7% versus 5.7%, p=0.0398) was achieved on decitabine-sapacitabine. There was a numerical difference in median survival (6.4 versus 5.0 months, HR=0.85 [0.59, 1.24], p=0.41) favoring decitabine-sapacitabine but overall survival did not reach statistical significance.
In the subgroup without prior AHD (n=346) there was a numerical difference in median survival (5.9 versus 6.7 months, HR=1.08 [0.86, 1.35], p=0.52) favoring decitabine and CR rate (16.6% versus 12.9%) favoring decitabine-sapacitabine but neither reached statistical significance.
Cytogenetics
In the subgroup with other than unfavorable cytogenetics (n=288) there was a numerical difference in median survival (8.2 versus 5.7 months, HR=0.89 [0.69, 1.15], p=0.38) and CR rate (19.9% versus 11.6%, p=0.16) favoring decitabine-sapacitabine but neither reached statistical significance.
In the subgroup with unfavorable cytogenetics (n=194) there was a numerical difference in median survival (3.8 months versus 5.7 months, HR=1.27 [0.94, 1.73], p=0.12) favoring decitabine but overall survival did not reach statistical significance. There was a numerical difference in CR rate favoring decitabine-sapacitabine (12.0% versus 9.6%) but it did not reach statistical significance.
In the subgroup of patients with below 50% and with 50% or higher bone marrow blasts there were no statistically significant differences in overall survival between the arms.
Presentation
The presentation (abstract 891), titled "Results of a Phase 3 Study of Elderly Patients with Newly Diagnosed AML Treated with Sapacitabine and Decitabine Administered in Alternating Cycles," is available on the Cyclacel website at www.cyclacel.com.
About Sapacitabine
Sapacitabine (CYC682), an orally-available nucleoside analogue, is currently being studied in an ongoing, extension of a Phase 1 study evaluating a combination regimen of sapacitabine and seliciclib, a first generation CDK inhibitor. Parts 1 and 2 of the study evaluated approximately 90 patients with advanced cancers. Part 3 is ongoing in patients with BRCA positive, breast, ovarian and pancreatic cancer. Over 1,000 patients with hematological malignancies and solid tumors have received sapacitabine.
About AML
AML is a rapidly progressing cancer of the blood characterized by the uncontrolled proliferation of immature blast cells in the bone marrow. The American Cancer Society estimates there will be approximately 21,380 new cases of AML and approximately 10,590 deaths from AML in the U.S. in 2017. AML is generally a disease of older adults and the median age is about 67 years. Newly diagnosed elderly patients with poor prognostic risk factors typically die within one year.