Liveblogging First-Time Disclosures From #ACSSanDiego
Mar24

Liveblogging First-Time Disclosures From #ACSSanDiego

Watch this space on Sunday as I cover the public unveiling of five drug candidates’ structures. I’ll be liveblogging the “First Disclosures of Clinical Candidates” symposium at the San Diego ACS National Meeting, which runs from 2PM to 5PM Pacific. 1:30PM It’s half an hour before the start of the session and the big ballroom is still pretty empty. Expect that to change in short order. 2:30PM LX4211 Company: Lexicon Pharmaceuticals Meant to treat: type 2 diabetes Mode of action: dual inhibitor of sodium glucose transporters 1 and 2, which play key roles in glucose absorption in the gastrointestinal tract and kidney Medicinal chemistry tidbits: this drug candidate had Lexicon’s chemists refamiliarizing themselves with carbohydrate chemistry. Most inhibitors of sodium glucose transporters incorporate D-glucose in some way. Lexicon’s chemists realized they could try something different– inhibitors based on the scaffold of L-xylose, a non-natural sugar. The team has already published a J. Med. Chem paper (2009, 52, 6201–6204) explaining that strategy. LX4211 is a methyl thioglycoside-the team went with a methyl thioglycoside because upping the size too far beyond a methyl lost activity at SGLT1. Status in the pipeline: LX4211 is currently completing Phase IIb trials. 3:00PM BMS-927711 Company: Bristol-Myers Squibb Meant to treat: migraine Mode of action: antagonist of the receptor for calcitonin gene-related peptide- increased levels of this peptide have been reported in cases of migraine Medicinal chemistry tidbits: This team recently published an orally bioavailable CGRP inhibitor, BMS-846372 (ACS Med. Chem. Lett., DOI: 10.1021/ml300021s). However, BMS-846372 had limited aqueous solubility, something that might make its development challenging. To improve that solubility, the BMS team sought to add polar groups to their molecule, something that’s been tough to do with CGRP inhibitors historically. In the end, the team managed to add a primary amine to BMS-846372’s cycloheptane ring while maintaining CGRP activity, leading to BMS-927711. Status in the pipeline: Phase II clinical trials 3:05 lots of questions from the audience for this talk! One questioner notes (as was noted in talk) that 4 CGRP inhibitors had gone before this drug in the clinic, and not made it through. Speaker notes that this candidate is more potent than others at CGRP (27 picomolar). 3:53 We’re a bit behind schedule but got plenty of good chemistry… GSK2636771 Company: GlaxoSmithKline Meant to treat: tumors with loss-of-function in the tumor suppressor protein PTEN (phosphatase and tensin homolog)- 2nd most inactivated tumor suppressor after p53- cancers where this is often the case include prostate and endometrial Mode of action: inhibitor of phosphoinositide 3-kinase-beta (PI3K-beta). Several lines of evidence suggest that proliferation in certain PTEN-deficient tumor cell lines is driven primarily by PI3K-beta....

Read More

Genentech Says Experimental Cancer Combo is Safe

Genentech this week unveiled promising results from a Phase I study suggesting it is possible to safely combine two cancer drug candidates, its MEK inhibitor GDC0973 and its PI3K inhibitor GDC0941. In addition to a relatively clean safety profile, there were also early signs that the combination is combating cancer. Genentech is one of several companies running a trial to test the safety of combining inhibitors of the lipid kinase PI3K, part of the PI3K/AKT/mTor pathway, and drugs blocking the protein kinase MEK, part of the KRas/MAP signalling pathway. As we discuss in our upcoming April 11th cover story on PI3K inhibitors, the rationale for knocking down both pathways  is compelling: both are considered to be crucial in cancer cells’ survival, and blocking only one pathway has more often than not proven ineffective. As Robert Abraham, CSO of Pfizer’s oncology research unit, explains in Monday’s story: “KRas mutations are associated with many of the deadliest cancers,” including colorectal and pancreatic, Pfizer’s Abraham says. Yet they are incredibly resistant to conventional chemotherapy, and based on preclinical studies of the mutations, are expected to be resistant to the new batch of mTor/PI3K inhibitors as well, he adds. The working hypothesis is that knocking out two of the major drivers of cancer—the KRas and PI3K pathways—could have a significant effect on the most recalcitrant tumors. To date, there are at least six Phase I trials planned or ongoing that combine MEK inhibitors with compounds that block some aspect of the mTor/PI3K pathway. Merck and AstraZeneca made headlines in 2009 when they said they would partner to test Merck’s AKT inhibitor with AstraZeneca’s MEK inhibitor. Sanofi-Aventis has meanwhile teamed with Merck Serono to explore the potential of combining two of its PI3K inhibitors in combination with Merck Serono’s MEK inhibitor. GlaxoSmithKline has two of its own drugs in a combination trial, and its MEK inhibitor GSK1120212 is also being tested in combination with Novartis’ PI3K inhibitor BKM120. And while Pfizer has yet to initiate such a study, Abraham said the company is “keeping two eyes on that combination.” We go into much more detail in Monday’s cover story about the efforts to match PI3K inhibitors with other drugs, and the rationale behind different flavors of compounds (mTor/PI3K inhibitors vs. pan-PI3K inhibitors vs. single-isoform inhibitors). Stay...

Read More