BI 6727, a Polo-like kinase inhibitor with improved pharmacokinetic profile and broad antitumor activity.
OBJECTIVE
Antimitotic chemotherapy remains a cornerstone of multimodality treatment for locally advanced and metastatic cancers. To identify novel mitosis-specific agents with higher selectivity than approved tubulin-binding agents (taxanes, Vinca alkaloids), we have generated inhibitors of Polo-like kinase 1, a target that functions predominantly in mitosis.


METHODS
The first compound in this series, suitable for i.v. administration, has entered clinical development. To fully explore the potential of Polo-like kinase 1 inhibition in oncology, we have profiled additional compounds and now describe a novel clinical candidate.


RESULTS
BI 6727 is a highly potent (enzyme IC(50) = 0.87 nmol/L, EC(50) = 11-37 nmol/L on a panel of cancer cell lines) and selective dihydropteridinone with distinct properties. First, BI 6727 has a pharmacokinetic profile favoring sustained exposure of tumor tissues with a high volume of distribution and a long terminal half-life in mice (V(ss) = 7.6 L/kg, t(1/2) = 46 h) and rats (V(ss) = 22 L/kg, t(1/2) = 54 h). Second, BI 6727 has physicochemical and pharmacokinetic properties that allow in vivo testing of i.v. as well as oral formulations, adding flexibility to dosing schedules. Finally, BI 6727 shows marked antitumor activity in multiple cancer models, including a model of taxane-resistant colorectal cancer. With oral and i.v. routes of administration, the total weekly dose of BI 6727 is most relevant for efficacy, supporting the use of a variety of well-tolerated dosing schedules.


CONCLUSIONS
These findings warrant further investigation of BI 6727 as a tailored antimitotic agent; clinical studies have been initiated.
Rudolph
Dorothea
D
Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria.
Steegmaier
Martin
M
Hoffmann
Matthias
M
Grauert
Matthias
M
Baum
Anke
A
Quant
Jens
J
Haslinger
Christian
C
Garin-Chesa
Pilar
P
Adolf
Günther R
GR
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D005260:Female; D005455:Fluorescent Antibody Technique; D051858:Forkhead Transcription Factors / Q000502:physiology; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011621:Pteridines / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D023041:Xenograft Model Antitumor Assays; D000097869:Polo-Like Kinase 1
D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D051858:Forkhead Transcription Factors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011621:Pteridines; D000097869:Polo-Like Kinase 1; C541363:BI 6727; C090140:Whn protein