Treatment of hematologic malignancies and solid tumors by inhibiting IGF receptor signaling

Insulin-like growth factors (IGF) and their receptors (IGF-1R) constitute a complex biologic system implicated in diverse regulatory levels of cell proliferation, viability, differentiation and metabolism. Extensive epidemiologic data have implicated the IGF/IGF-1R pathway in the establishment of human malignancies, consistent with experimental data on the role of this signaling cascade in promoting cell transformation, resistance to apoptosis, metastases and other aspects of the biology of human cancers. However, historically, the IGF/IGF-1R pathway has not been viewed as an attractive target for therapeutic intervention. The widespread IGF-1R expression in normal tissues and its close homology to the insulin receptor had led to the assumption that IGF-1R inhibition would cause unacceptable toxicities in vivo. Even though neutralizing antibodies against human IGF-1R have been efficacious against xenograft tumors, a lack of reactivity against the host rodent receptor has confounded the assessment of its therapeutic index. Furthermore, the lack of a clear understanding of the relevant significance for neoplastic cells in the function of IGF-1R versus other growth factor receptors provided an additional disincentive for the study of this pathway. However, recent reports from the authors' group and others have shown that small molecule inhibitors of tyrosine kinase activity of IGF-1R can be safely and efficaciously administered in vivo in clinically relevant orthotopic models of human neoplasias, such as multiple myeloma. This article reviews the data that validated IGF-1R as a therapeutic target for a broad spectrum of malignancies and provides in vivo proof-of-concept for the use of selective IGF-1R kinase inhibitors as primary antitumor therapy or in synergistic combination as chemosensitizers. These results have not only provided the rationale for clinical trials of small molecule IGF-1R inhibitors, but have also rekindled interest in other therapeutic modalities (e.g., monoclonal antibodies) aimed at suppressing the function of this critical pathway for tumor cell pathophysiology.

Jerome Lipper Multiple Myeloma Center, Dana Farber Cancer Institute, Department of Medicine, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.

MIT engineers an anti-cancer nanotechnology smart bomb

Imagine a cancer drug that can burrow into a tumor, seal the exits and detonate a lethal dose of anti-cancer toxins, all while leaving healthy cells unscathed.

MIT researchers have designed a nanoparticle to do just that.

The dual-chamber, double-acting, drug-packing "nanocell" proved effective and safe, with prolonged survival, against two distinct forms of cancers-melanoma and Lewis lung cancer-in mice.

The work will be reported in the July 28 issue of Nature, with an accompanying commentary.

"We brought together three elements: cancer biology, pharmacology and engineering," said Ram Sasisekharan, a professor in MIT's Biological Engineering Division and leader of the research team.

"The fundamental challenges in cancer chemotherapy are its toxicity to healthy cells and drug resistance by cancer cells," Sasisekharan said. "So cancer researchers were excited about anti-angiogenesis," the theory that cutting off the blood supply can starve tumors to death. That strategy can backfire, however, because it also starves tumor cells of oxygen, prompting them to create new blood vessels and instigate metastasis and other self-survival activities.

The next obvious solution would be combining chemotherapy and anti-angiogenesis-dropping the bombs while cutting the supply lines. But combination therapy confronted an inherent engineering problem. "You can't deliver chemotherapy to tumors if you have destroyed the vessels that take it there," Sasisekharan said. Also, the two drugs behave differently and are delivered on different schedules: anti-angiogenics over a prolonged period and chemotherapy in cycles.

"We designed the nanocell keeping these practical problems in mind," he said. Using ready-made drugs and materials, "we created a balloon within a balloon, resembling an actual cell," explains Shiladitya Sengupta, a postdoctoral associate in Sasisekharan's laboratory.

In addition to Sasisekharan and Sengupta, the co-authors are David Eavarone, Ishan Capila and Ganlin Zhao of MIT's Biological Engineering Division; Nicki Watson of the Whitehead Institute for Biomedical Research; and Tanyel Kiziltepe of MIT's Department of Chemistry.

The team loaded the outer membrane of the nanocell with an anti-angiogenic drug and the inner balloon with chemotherapy agents. A "stealth" surface chemistry allows the nanocells to evade the immune system, while their size (200 nanometers) makes them preferentially taken into the tumor. They are small enough to pass through tumor vessels, but too large for the pores of normal vessels.

Once the nanocell is inside the tumor, its outer membrane disintegrates, rapidly deploying the anti-angiogenic drug. The blood vessels feeding the tumor then collapse, trapping the loaded nanoparticle in the tumor, where it slowly releases the chemotherapy.

The team tested this model in mice. The double-loaded nanocell shrank the tumor, stopped angiogenesis and avoided systemic toxicity much better than other treatment and delivery variations.

But it is patient survival and quality of life that really inspire this research, Sasisekharan said. Eighty percent of the nanocell mice survived beyond 65 days, while mice treated with the best current therapy survived 30 days. Untreated animals died at 20.

"It's an elegant technique for attacking the two compartments of a tumor, its vascular system and the cancer cells," said Judah Folkman of Children's Hospital Boston. "This is a very neat approach to drug delivery," said MIT Institute Professor Robert Langer.

The nanocell worked better against melanoma than lung cancer, indicating the need to tweak the design for different cancers. "This model enables us to rationally and systematically evaluate drug combinations and loading mechanisms," says Sasisekharan. "It's not going to stop here. We want to build on this concept."

Source: MIT News Office http://web.mit.edu/newsoffice/2005/nanocell.html

Nanotech Moves Closer to Cure

When Dr. James Baker returned from the first Gulf War in 1991, his University of Michigan colleagues must have assumed the medical researcher's head had sustained a direct Scud missile hit. The good doctor came home with some pretty wacky ideas.

Here was one of them: Instead of using live viruses to destroy diseased cells, why not send in man-made, nanoscale molecules with tiny tendrils that scientists could engineer to battle specific types of cancers?

Remember, this was the early '90s. Few had even heard of the internet, much less "nanotechnology," which was then firmly the domain of futurists, and certainly not on the radar of respectable beaker slingers.

"In fact, there was a lot of derision at NIH (National Institutes of Health) that this was not real science," Baker recalls. "But as it became clear that gene therapy was not going anywhere without different approaches, I think the reality of, the necessity of, bioengineering in this process became clear."

Today, the National Cancer Institute is on its way to becoming a Nano Cancer Institute as it prepares to spend $144.3 million over five years on the engineered nanoparticles "approach" that Baker and just a few others had championed more than a decade ago. As for Baker, he's doing rather well in his corner office at the Center for Biologic Nanotechnology with a panoramic view of downtown Ann Arbor, Michigan.

Baker had been involved in the Army's first attempts at DNA delivery of the adeno vaccine to combat acute respiratory illness among the troops. He found that not only was the body's immune system fighting off the viral-based vaccine, but the entire works were coming to "hard stops" at 150 nanometers. Things just did not get into cells very effectively beyond that.

It seemed clear to Baker that engineered nanoparticles would have to become part of the solution if they wanted to really chase after the bad guys in the body. "If we now want to fix the dysfunction of cells that lead to most of the diseases that we're currently fighting, we have to engineer at the same scale as the cells," Baker says.

That's the problem that was swirling around in Baker's head after the Gulf War. He wasn't the only scientist working on it, but he did have one advantage. He's located just 100 miles south of a nanotech pioneer: former Dow chemist Donald Tomalia, who had invented a type of particle called dendrimers. Tomalia realized -- unfortunately about two decades before the rest of the world -- that his man-made, tendriled molecule could be used in targeted drug delivery.

Tomalia saw that Baker was one of the few scientists at the time who also saw the possibilities within these sticky little nanothings. "He was a medical guy who could understand this," Tomalia says. "I think he very quickly began to realize the important implications that dendrimers would have."

All through the mid- and late '90s, Baker and Tomalia quietly experimented with these particles. A synthetic chemist and a medical researcher made for an odd couple at the time.

Lack of cooperation and understanding between the scientific disciplines is one of the toughest challenges facing nanotech researchers. Cooperation may sound simple to those outside the academic world, but cross-disciplinary collaboration is not the way universities have traditionally been organized.

That's the thinking behind the University of Michigan's new Nanotechnology Institute for Medicine and the Biological Sciences, which Baker will head. "I think any university that doesn't develop collaborative centers like this is going to be frozen out," he says.

The convergence of the sciences at Michigan has led to dramatic success of late. Baker's lab recently received a $6.3 million Gates Foundation grant to develop hepatitis B vaccines that can be delivered through the nose, rather than by needle. They will be able to survive outside a refrigerator, making them easier to use in developing nations. And a breakthrough announced in late June heralded a new kind of cancer therapy that acts as a kind of "Trojan horse," infiltrating cancer-cell receptors then turning the cancer against itself.

"I think one of the things that's really important is we actually can, for the first time, show that something injected not only gets into the cancer tumor, but actually gets into the cancer cells themselves," Baker says. "This is very important for both diagnosis and therapy."

The next challenge is getting any of this through the FDA, which is at once under pressure to speed up new drug approvals for an aging population, and to slow down the process in light of recent scandals involving bad side effects.

"Celebrex, Vioxx, all of these drugs that popped up here recently with problems, are whole-body administered -- they go everywhere," Tomalia says. "They think they know where they have gone in all minute detail, and they think they know every enzyme and every receptor site, but you never really quite know."

The best-case scenario, Baker says, is nanotech-enabled cancer therapy in your doctors' office within five years. But that's assuming an accelerated approval process, being pushed by nanotech advocates, which is by no means a foregone conclusion. Left to the normal FDA process, it could be a decade or more.

"We've all got relatives or friends who have died from this," he says. "The therapy is almost worse than the disease." If nothing else, perhaps the end of painful chemotherapy is in sight. "If we can make the therapy nontoxic ... then that's much more practical."

Source: http://www.wired.com/news/medtech/0,1286,68195,00.html

Millennium Pharma Outlook: 'The Worst Is Over'

SG Cowen said "the worst is over" for shares of Millennium Pharmaceuticals (nasdaq: MLNM) after the specialty pharmaceutical firm announced last Friday it would divest the Integrilin heart drug to Schering-Plough.

"We have a neutral opinion of this deal, and Millennium's shares in general. We still do not recommend Millennium because our physician checks have not yet given us any reasons for optimism that there will be an upside surprise from Velcade, Integrilin, or Millennium's pipeline," said SG Cowen. "Nonetheless, we acknowledge that the current stock price positions Millennium for outperformance should Velcade begin to look like a winner in an indication outside refractory myeloma, and we will watch for such an opportunity."

The research firm said one positive of the deal is that it signifies Millennium is becoming more focused on its lead drug Velcade, a cancer treatment, as competition heats up in the multiple myeloma space. "With Millennium off 20% in 2005, we believe the worst is over for the stock," said SG Cowen.

Source: http://www.forbes.com/markets/2005/07/25/millennium-pharmaceuticals-earnings-0725markets11.html

Ontario myeloma patients await Velcade funding

Many people in Ontario, Saskatchewan and Quebec are celebrating this weekend after their provincial governments approved the expensive breast cancer drug Herceptin.

But for a group of people in Ontario suffering from a type of cancer with its own fast-tracked wonder drug that didn't get funded, the announcement brought only disappointment and feelings of desperation.

"You realize you need this drug and you can't have it, and there are no other options,'' said Dr. Donna Reece, director of the multiple myeloma program at Princess Margaret Hospital in Toronto. "They're terrified.''

Multiple myeloma is a blood cancer that slowly eats away at tissue in the bone marrow. There is no cure for the disease, Reece said during a break from a conference aimed at educating newly diagnosed patients.

But a drug called Velcade has been shown to batter it into remission for about 18 months in advanced cases where death would usually be imminent, she said. Health Canada approved Velcade in January and every other province but Ontario has made funding available for it.

Carolyn Henry has had multiple myeloma for almost six years and she said she can't believe Ontario is the only province in Canada to not fund the drug.

"My next appointment is in two weeks and my name could be on that list of people who urgently need Velcade,'' she said quietly.

"I have a daughter that just finished first year university. I'd really like to see her graduate, to get married. I have lots of living left to do.''

Reece, who has done some consulting about multiple myeloma with the drug company that makes Velcade but does not get paid for getting patients to take it, said since both Herceptin and Velcade were fast-tracked through the approval process, she had been hoping funding for both would come at once.

She called the moment when she figured out Herceptin would be funded but Velcade wouldn't "heartwrenching.''

"This is creating a real hardship for patients, because the drug is effective,'' she said. "It is life-saving when all other treatments have failed.''

Ontario Health Ministry officials say Velcade is still in the midst of the review process.

But Health Minister George Smitherman's comments at a news conference to announce Herceptin's funding didn't inspire optimism, Reece said.

Smitherman said funding Herceptin and two other cancer drugs would increase spending on cancer care in the province by up to 70 per cent per year.

He said this would result in some "tough choices'' when it comes to deciding what other drugs to fund -- adding it's hard to say no when lives are at stake, but it's impossible to say yes all the time. According to statistics from the National Cancer Institute of Canada, about 1,840 people are diagnosed with multiple myeloma per year, 730 of them in Ontario.

Reece said at least a couple hundred of these people could benefit from Velcade immediately, and over time every single patient could need it.

Dr. Brian Durie, who came to the conference from Cedars-Sinai hospital in Los Angeles, said he recently conducted a study in which Velcade was used as soon as people were diagnosed.

"It probably had the highest response of any drug that has ever been used as a first response,'' he said. "But for whatever reason, it isn't approved for use here in Ontario.''

The drug is about as costly as Herceptin. Reece said an average dose over five months would come to about $35,000.

"As a patient possibly needing this drug, I don't care how much it costs,'' said Henry. "How can you say you're not worth it?''

Durie said he has helped patients go to the United States to receive the treatment.

Reece said that's really the only option for Ontario patients right now since it can take months to get covered by another province's health plan -- so merely moving to Manitoba, for example, wouldn't mean an Ontario patient could get Velcade right away.

"I think we try to send people down to the U.S. but most people simply can't afford it, so it's not a realistic option,'' she said. "It's not the answer.''

Henry said she used to work as a nurse and never once thought Canada's health-care system would deny a patient something they need to survive.

"When you hear these arguments (about money), you feel very marginalized in our current society, as an individual,'' she said. "And I honestly thought that's what our health-care system was supposed to avoid.''

Immune Control Gets $11.3M for Serotonin Work

Immune Control Inc. raised $11.3 million in its Series A financing to develop serotonin antagonists for lymphocytic cancers and autoimmune diseases, and to begin the first two clinical programs in multiple myeloma and psoriasis.

The company's work is based on serotonin being a critical factor for the replication of activated immune cells, and that blocking the serotonin receptors could cause apoptosis in activated lymphocytes.

Serotonin receptors have been targets for years in the area of central nervous system (CNS) disorders and diseases, and have been involved in the discovery of antidepressants and antipsychotics, as well as selective serotonin reuptake inhibitors such as Paxil and Prozac. But, until recently, Roth said, there seemed to be a general consensus that serotonin was active only in CNS.

One of Immune Control's scientific founders, Brad Jameson, presented work that uncovered a connection between serotonin receptors and immune cells. Jameson, a professor of biochemistry at Drexel's College of Medicine, had been working on a peptide that could interfere with the attachment of HIV to cell sites when he made the discovery, Roth said.

"This means serotonin potentially can be [targeted] in immune indications," he said, including rheumatoid arthritis, Type I diabetes, lupus and organ transplant rejection.

Immune Control, which exclusively licensed patents relating to serotonin receptors from Drexel, will be working with already-marketed antagonists that are supported by considerable safety data, as well as supporting research to developing its own antagonists. The company's focus will be on creating products that do not go into the central nervous system, or cross the blood-brain barrier, to prevent the common side effects of serotonin-targeted drugs.

Roth said the company also has agreement to test serotonin antagonists developed by an unnamed large pharmaceutical company that have not been commercialized because they don't enter the central nervous system.

Immune Control's human trials are expected to begin with a study in patients with multiple myeloma, a cancer that affects B cells. A second clinical study is expected to test a serotonin antagonist in psoriasis, a T-cell disease.

"We're hoping to have both in trials by the end of 2005," he said.

Ontario draws fire over cancer drugs

Funding procedure cited as reason for critical delays

The Globe and Mail
By Carolyn Abraham, Medical Reporter
Wednesday, July 13, 2005 Page A5

Ontario is attracting criticism as a slow provider of breakthrough cancer treatments, as its patients are once again left desperate for access to a critical drug -- this one available in every other province.

Just as women with a particularly aggressive form of breast cancer have been anxiously waiting for Ontario to fund the potentially life saving drug Herceptin, people with multiple myeloma, a fatal blood cancer, are agonizing over whether the province will pick up the tab for Velcade, a new treatment that could also extend their lives.

"I'm 49 years old and I want to live, this is my last chance," said Neil Koven, a father of two teenaged sons who was diagnosed with multiple myeloma two years ago. "I don't understand the politics, why one province doesn't allow this. . . . You can't hop the fence and get another provincial health-care plan to give it to you, you have to be a resident."

The struggle for Velcade is the latest example of patients falling through the widening gap between new medical treatments and the public's ability to pay for them.

Observers blame the delays on changes made this year to Ontario's drug-funding-approval process so provincial officials could conduct a more thorough cost-benefit analysis of expensive new treatments coming down the pipe.

"The overall theme is that these drugs are not getting approved, or they are not getting approved in a timely fashion," said Keith Stewart, a medical oncologist who treats patients with multiple myeloma at Toronto's Princess Margaret Hospital. "The result is that patients in Ontario cannot get access to a drug people can get in every other province."

Velcade is considered a drug of last resort and the first new medication in nearly 40 years for patients with multiple myeloma, a cancer that strikes the blood's plasma cells. More than 6,000 people in Canada have the disease, with 1,500 new cases diagnosed annually. Generally, Dr. Stewart said, people survive an average of five years after diagnosis.

However, Velcade is a new class of medication that can force cancer cells to choke on their own proteins. It has the potential to extend life by more than two years, or 13 months on average, Dr. Stewart said. Treatments cost about $35,000 a patient.

The U.S. Food and Drug Administration approved Velcade two years ago. Health Canada approved it in January. In Quebec, hospitals that have the discretion to decide on the drugs they will provide began offering it to patients not long after.

Ortho Biotech, which markets the drug in Canada, said all other provinces except Ontario provide Velcade through their cancer agencies and hospitals on a patient-by-patient basis.

But in Ontario, Judy Glennie, associate director of the drug programs branch of the Ministry of Health and Long Term Care, said only that "Velcade is in the review process," and that no decision had yet been made as to whether the drug would be funded.

Neither could Ms. Glennie say when a funding decision on Herceptin would be made, only that efforts are under way to "expedite" its review.

She said that in the past Cancer Care Ontario made recommendations on new cancer drugs and then applied once a year to the ministry to fund them.

But under the new system, which took effect in February, a subcommittee of medical experts and ethicists makes a recommendation on the comparative value of a new drug to another committee, which makes a further recommendation to the ministry.

"I think, frankly, Ontario has been leading the way in the review process," Ms. Glennie said. "We're doing our best to look at this evidence as quickly as [we] can."

Terry Sullivan, president and CEO of Cancer Care Ontario, acknowledged that bugs must be worked out of the new system to speed up decisions, but he said Ontario's situation is not much different than other provinces.

"There is no province outside of B.C. that is paying for Herceptin on an as-needed basis," Dr. Sullivan said.

In the meantime, Dr. Koven, a podiatrist who ran his own practice in Mississauga, Ont., until he was too sick to work, is left wondering what he will do next.

Although he has already refinanced his home to pay the bills, Dr. Koven said he is considering how to get the drug he needs, now that chemotherapy, radiation and even a stem cell, bone-marrow transplant have left him with no other options.

Dr. Stewart, who ran clinical trials of Velcade and is a consultant for Ortho, said some patients are heading to Buffalo, but noted that "It's a difficult drug to go out of town to get," as it has to be administered intravenously twice a week.

Infinity Initiates Phase I Clinical Trial of IPI-504 for Multiple Myeloma

CAMBRIDGE, Mass. -- Infinity Pharmaceuticals, Inc. today announced the initiation of a phase I clinical trial of IPI-504, the company's Heat Shock Protein 90 (Hsp90) inhibitor and lead investigational anticancer agent. Research shows that inhibition of Hsp90 forces cancer cells to "commit suicide" through a process of programmed cell death or apoptosis. IPI-504 is initially being developed as a potential treatment for patients with multiple myeloma and will subsequently be developed for additional hematologic cancers and solid tumor indications.

This open-label safety assessment phase I trial of IPI-504 will evaluate the potential anti-tumor activity and the tolerability of various doses in subjects with relapsed or relapsed, refractory multiple myeloma. Initial subjects in the study are being treated at St. Vincent's Comprehensive Cancer Center in New York under the direction of Sundar Jagannath M.D.

"We are excited and encouraged to begin our first clinical trial of IPI- 504 and look forward to further exploring its use as a single agent and in combination with other chemotherapeutic agents to attack cancer cell survival," said Julian Adams, Ph.D., Chief Scientific Officer, Infinity. "A key advantage of the compound relative to other Hsp90 inhibitors is its intravenous administration to patients using a simple water-based formulation."

IPI-504 is an innovative and proprietary small molecule compound specifically designed to attack a cancer cell's machinery for maintaining protein homeostasis, the process by which cells continue the orderly formation and destruction of proteins. Infinity presented preclinical data on IPI-504 during the 96th Annual Meeting of the American Association for Cancer Research held in Anaheim, California in April 2005. In vitro studies demonstrate that IPI-504 binds to Hsp90 more tightly than 17-AAG. In addition, IPI-504 acting as a sole agent shows potent cytotoxic activity against multiple myeloma cells which are resistant to current therapies including bortezomib-resistant cells. When examined in vivo, IPI-504 demonstrated a 71% reduction in multiple myeloma tumor growth relative to controls in a preclinical xenograft model. It was also found to decrease serum Immunoglobulin lambda chain concentrations (similar to M protein in the human disease), enabling monitoring of disease burden with a surrogate marker. Furthermore, in vivo reduction in tumor growth was also observed in several other human xenograft models, including models of breast, prostate and ovarian cancer.

Anderson Cancer Researchers Publish Manuscript on Callisto 's Atiprimod

Anderson Cancer Researchers Publish Manuscript on Callisto Pharmaceuticals’ Atiprimod in British Cancer Journal of Cancer

NEW YORK, NY – Callisto Pharmaceuticals, Inc. (AMEX: KAL), a biopharmaceutical company primarily focused on the development of drugs to treat cancer, announced the publication of a paper entitled “Atiprimod Blocks STAT3 Phosphorylation and Induces Apoptosis in Multiple Myeloma Cells,”. It appeared in the British Journal of Cancer, Volume 92, Number 13, pp.1-11 (2005.), and was authored by a team of scientists and clinicians from the University of Texas M.D. Anderson Cancer Center, highly-regarded experts in multiple myeloma, blood cancers and bioimmunotherapy. The publication provides further evidence that Atiprimod has anti-neoplastic effects on human myeloma cells in culture, and further elucidated the biological mechanisms by which Atiprimod exerts these anti-neoplastic effects.

“The team of scientists and clinicians who participated in this study has an impressive record of advancements in the basic science of blood cancers, as well as a proven record of success in the clinic.” said Dr. Gary S. Jacob, Chief Executive Officer of Callisto Pharmaceuticals. “Atiprimod is currently being evaluated at M.D. Anderson in a Phase I/IIa clinical trial in patients with relapsed multiple myeloma, as well as in a single agent trial in advanced cancer patients.”

In the present work, Atiprimod’s effects on proliferation of myeloma cells, and on the key signaling pathways in myeloma cells were evaluated. Atiprimod was shown to inhibit proliferation in a time- and dose-dependent manner, and to arrest myeloma cell growth, preventing cell cycle progression. Furthermore, Atiprimod inhibited STAT 3 activation, blocking the signaling pathway of interleukin-6, which contributes to myeloma cell proliferation and survival. Incubation of myeloma cells with Atiprimod induced apoptosis (cell death) through the activation of caspase 3, leading to deactivation of the DNA repair enzyme PARP.

In separate experiments, Atiprimod suppressed myeloma colony-forming cell proliferation of fresh marrow cells from five patients with newly diagnosed MM in a dose-dependent fashion.

Atiprimod is currently being evaluated in a Phase I clinical trial in relapsed or refractory multiple myeloma patients at four clinical sites in the United States – the Dana-Farber Cancer Institute (Boston, MA), the M.D. Anderson Cancer Center (Houston, TX), the St. Vincent’s Comprehensive Cancer Center (New York, NY) and the Roswell Park Cancer Institute (Buffalo, NY). On May 4, 2005 Callisto announced that three patient cohorts had completed dosing at 30, 60 and 90 mg, respectively, and a fourth dosing cohort was underway at 120 mg. No dose limiting toxicities had been observed, and a fifth dose cohort at 180 mg was anticipated to begin in the following 6-8 weeks.