Pfizer Reports Sutent Safe And Effective In Asians, Forges Alliances With Major Asian Oncology Centers

Pfizer may draw on Sutent research centers for trials on other oncology therapies such as axitinib and figitumumab, an insulin growth factor receptor inhibitor.

PERTH, Australia - Pfizer's Phase IIIb Asian trial of its leading oncology drug multi-kinase inhibitor Sutent demonstrated similar effectiveness and tolerability in Asians as in non-Asians, in data the company released Sept. 21.

Conducted at 246 sites in 52 countries, including Korea, Hong Kong, Malaysia, Philippines, Singapore, Taiwan and Thailand, the prospective Phase IIIb study evaluated safety and efficacy of sunitinib in Asian patients with metastatic renal cell carcinoma. It was conducted as an additional trial begun prior to regulatory approval for sunitinib in those countries, Pfizer Clinical Development and Medical Affairs VP Susan Lowenthal said in an interview.

She explained that the trial "was meant to make the drug available to patients who were not eligible for other sunitinib trials and were judged to be potentially patients who could benefit from sunitinib."

"The importance of this trial is that here we have 325 Asian patients who are the largest number of Asian patients in all of our trials and we can understand how sunitinib works in those Asian patients with kidney cancer and we can now evaluate the efficacy and safety in that patient population, which is the largest to date," she said.

The retrospective data analysis showed an overall response rate of 22 percent in Asian patients compared to 17 percent in non-Asian patients with a median overall survival of 18.9 months in Asians versus 18.4 months for non-Asian patients. During the study, the dose was reduced from the starting 50 mg down to 37.5 mg in 32 percent of Asian patients compared to 33 percent in non-Asian patients.

When asked about next steps, Lowenthal said that sunitinib is already approved for renal cell carcinoma in those Asian countries based on registration studies conducted in the United States and Europe, but that the data reassures that the drug is metabolized similarly in Asians.

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No Difference In Metabolism In Asians

She noted that it has been known for awhile that metabolizing enzymes may be different in Asian patients and with new targeted treatments it was important to know how metabolism factored in.

While there were not any significant safety signals, there were differences in frequency in some of the side effects in Asians in comparison to the non-Asians that were analyzed.

"For example, there was an increase in frequency of hand-foot syndrome and bone marrow effect on platelets and white [cell] count, but these were easily manageable with appropriate monitoring and dose titration," she said.

She also noted that some side effects such as diarrhea were less frequent in the Asian population.

"This data from an exploratory analysis of a large group of patients in the "real world" setting provides further evidence that Sutent is a safe and effective option in the management of RCC in Asia," Pfizer spokeswoman Neena Moorjani added. "The differences seen in the pattern of adverse events reflect what has been seen in the clinical setting and provides a window into areas of future research and exploration. It's important to note that the AEs were manageable and the life-enhancing efficacy was similar to that seen in non-Asian patients."

Forging Alliances With Medical Centers In Asia

Pfizer conducted the clinical trials in partnership with academic medical centers; the larger ones were Seoul National University in South Korea, the Yonsei Cancer Center in Seoul and Singapore's National Cancer Center.

Having forged those partnerships, Lowenthal said it was likely that those centers will be used for additional Sutent trials as well as other oncology therapies currently in clinical development including Pfizer's axitinib and figitumumab, an insulin growth factor receptor inhibitor.

Two years after signing a memorandum of understanding with Korea's state-run Korea Research Institute for Bioscience and Biotechnology, Pfizer signed a more formal agreement last May to begin collaborative research projects for developing drugs to treat liver and gastric cancer (Also see "Pfizer Korea Signs Development Pact With State KRIBB For Liver and Gastric Cancer Drugs" - Scrip, 18 May, 2009.).

"Pfizer is committed to executing our clinical trials in Asia and this really was the first large study that we partnered with Asian oncologists in many different countries, and since then we are doing over 40 oncology clinical trials in many different countries in Asia and our experience has been very positive," Lowenthal said.

Pfizer is also making Sutent available to patients with serious cancers in China's rural countryside. Pfizer CEO Jeff Kindler recently visited grassroots medical institutions in Luzhou, a small town in Sichuan (Also see "As Merger With Wyeth Hangs In The Balance Of Beijing's Hands, Pfizer CEO Tours China To Launch Scholarly Partnerships" - Scrip, 30 Jul, 2009.). Pfizer and Tsinghua University are collaborating on a long-distance medical training project to train physicians from outlying areas. Pfizer also plans to keep in touch remotely with rural doctors through the exercise even if Sutent is not prescribed. Instead of limiting itself to the high-end market, the company aims to expand its coverage from the current 170 cities to 600 over several years.

Indeed, global reach is where Pfizer has seen the largest growth for Sutent. For the first half of 2009, U.S. sales for Sutent were $123 million, compared to $302 million in international sales. For the same period in 2008, U.S. Sutent sales stood at $126 million compared to $275 million in international sales.

Pfizer said it aims to be one of the top three oncology manufacturers by 2018 by focusing investments on the most prevalent tumors, paying attention to adjuvant therapies and committing to the next-generation of targeted therapies. With 21 drugs in the clinic and Sutent, Pfizer's top oncology drug, the goal is "well within our reach," according to the company (Also see "Pfizer’s Business Units Enable It To Be Nimble Even as It Grows" - Pink Sheet, 18 Mar, 2009.).

Competitors in the RCC space include Bayer's Nexavar (sorafenib), Wyeth's mTOR inhibitor Torisel (temsirolimus) and Novartis' newly approved oral kinase inhibitor Afinitor (everolimus).

GlaxoSmithKline's NDA for its VEGF receptor inhibitor Votrient (pazopanib) in advanced renal cell carcinoma is scheduled to be reviewed by U.S. FDA's Oncologic Drugs Advisory Committee Oct. 5. GSK is already running a head-to-head comparison with Sutent (" (Also see "ODAC To Assess Schering's PegIntron and GSK's Votrient In October" - Pink Sheet, 27 Aug, 2009.)).

- Tamra Sami ([email protected])