Genentech Data Bring Jitters

Its blockbuster Avastin cancer drug is showing a bit of its age.
Author:
Publish date:

CHICAGO -- The annual meeting of the American Society of Clinical Oncology has traditionally been the forum where

Genentech

(DNA)

and its blockbuster cancer drug Avastin run away with best-in-show honors.

At this year's confab, however, Avastin is showing a bit of its age. It's still a hugely important drug, but clinical data presented lacked pizzazz:

A phase III lung cancer study of low and high doses of Avastin combined with a chemotherapy regimen popular in Europe showed equal efficacy and lower toxicity at the low dose.

The data are potentially damaging to Genentech's revenue line if doctors both in Europe and the U.S. switch patients to lower doses of Avastin. Currently, doctors treat lung cancer patients with higher doses of Avastin.

In a second study, the addition of Avastin to a standard treatment for kidney cancer doubled progression-free survival and showed a positive trend toward prolonging survival.

This is good news for Avastin, but with a catch: kidney cancer patients are now being treated with several new targeted drugs, including

Pfizer's

(PFE) - Get Report

Sutent and

Onyx Phamaceuticals'

(ONXX)

Nexavar. A third drug, Torisel from

Wyeth

, was just approved by the Food and Drug Administration.

In other words, kidney cancer has become a crowded field, so the Avastin regimen, which combines the drug with interferon, is no longer considered a standard treatment.

VEGF-Trap, a potential Avastin competitor under development by

Regeneron Pharmaceuticals

(REGN) - Get Report

, reported disappointing data in a phase II ovarian cancer study. Avastin reported better ovarian cancer data at last year's ASCO meeting, so the VEGF-Trap stumble will likely be seen as an advantage of Genentech.

Let's go through each study in more detail:

Avastin is currently approved for use in the U.S. to treat advanced non-small cell lung cancer when given in combination with carboplatin and paclitaxel, two common chemotherapy drugs.

In Europe, the chemotherapy regimen most commonly used to treat lung cancer patients is cisplatin and gemcitabine, so investigators there ran a phase III study -- dubbed AVAIL -- looking to see whether the addition of Avastin would also benefit patients.

Like in the U.S., Avastin worked when added to the European chemo regimen, but it was slightly more effective at a lower dose (7.5 mg) compared to the higher dose (15 mg) used in the U.S.

When investigators looked at the safety data for the two Avastin doses, the low dose also appeared superior to the high dose across most categories.

The worry for Genentech from a business perspective is that a lower dose of Avastin equates to lower revenue. While this revenue falloff may be contained to Europe, where the Avastin plus cisplatin-gemcitabine regimen is used more, there is the possibility that oncologists here will interpret these data to mean that they can also use a lower dose of Avastin in combination with carboplatin and paclitaxel.

Investors have digested some of the negative impact of the AVAIL study already. When top-line results were announced earlier this year, sell-side analysts cut their Avastin revenue forecasts accordingly.

In the second kidney cancer study, the combination of Avastin with interferon doubled progression-free survival to 10.2 months, compared with 5.4 months for patients given interferon alone. The tumor response rate for the Avastin regimen was 30.6% compared with 12.4% for the interferon-only arm of the study.

While positive, these results aren't likely to persuade doctors to use more Avastin with their kidney cancer patients. By comparison, Pfizer's Sutent, used by itself, boosted progression-free survival to 11.8 months compared with 6.2 months for interferon alone.

Sutent is now considered the first-line standard of care for kidney cancer patients, with Onyx's Nexavar being used once patients' tumors start growing again, or in patients who can't tolerate Sutent.

Lastly, there's the data from Regeneron's VEGF-Trap. This drug -- which works by cutting off the blood supply to tumors -- has been the focus of much investor attention because of its potential as a potent Avastin competitor.

Regeneron enrolled 162 patients with advanced ovarian cancer that was resistant to chemotherapy. Patients were then randomized to receive one of two doses of VEGF-Trap.

Preliminary results from 153 patients from both dosage groups found that tumors shrank in 8% of patients. Tumors stopped growing in another 71% of patients. On the safety side, 1% of patients experienced perforations in their bowel, a potentially fatal side effect.

An 8% response rate to a drug in this patient group is positive, but the VEGF-Trap data does not surpass similar data from Avastin presented last year. In that study,Avastin produced a 16% rate of tumor shrinkage.

Adam Feuerstein writes regularly for RealMoney.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

click here

to send him an email.