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LAKE OSWEGO, Oregon (
TheStreet) -- More red flags have been found staked into
Galena Biopharma's(GALE - Get Report) breast cancer vaccine NeuVax.
Updated, 60-month follow-up results from a Neuvax phase II study scheduled for presentation next month at the American Society of Clinical Oncology (ASCO) annual meeting don't appear to be new or consistent with previously reported data.
Galena presented the same 60-month NeuVax analysis last December at the San Antonio Breast Cancer Symposium except the numbers are different.
Asked to explain the discrepancies between NeuVax data from last December and "new" NeuVax data coming next month at ASCO, Galena spokeswoman Remi Bernarda told me, "I don't have answers from the company at this time."
Let's dig into the controversy:
NeuVax research abstract submitted for next month's ASCO meeting -- posted on May 16 -- describes a subset of 53 patients from the phase II trial (187 patients were enrolled overall) who were "optimally dosed" with booster shots every six months following an initial set of six monthly injections. The booster shots were designed to enhance or prolong the immunotherapeutic effect of NeuVax.
At a median follow up of 60 months, the recurrence rate was 3.8% for the boosted NeuVax patients compared to 18.9% for the study's control group. Recurrence rate refers to the percentage of patients diagnosed with a re-emergence of their breast cancer.
A low recurrence rate is preferred for obvious reasons. Conversely, a higher "disease-free survival rate" is also preferred. DFS rate is defined as the percentage of patients still alive without their breast cancer returning.
It's easy to switch back and forth between recurrence rate and DFS rate since DFS rate equals 100 minus the recurrence rate. In Galena's ASCO abstract, therefore, the DFS rate for the 53 "optimally dosed" NeuVax patients is 96.2% versus a DFS rate of 81.1% for the control arm patients.
Here's where we get to the problem.
Last December, Galena presented a poster at the San Antonio Breast Cancer Symposium detailing results from the same 53 breast cancer patients treated with NeuVax booster shots every six months. Galena issued a press release on Dec. 7, 2011 to announce the results, which
reads in part:
"Of the 53 patients who received at least one booster inoculation, a statistically significant disease-free survival rate of 95.9% was seen versus 79.7% in the control group…"
Hmmm. The DFS rate from December's analysis of the 53 "optimally dosed" NeuVax patients is not the same as the DFS rate outlined in the ASCO abstract. How can that be? If Galena is describing the same patient subgroup (and it certainly seems like they are) the numbers should be the same.
Perhaps the data in the ASCO abstract is an update of the data presented last December? That's possible, although both reports say the analysis was done at a median follow-up of 60 months.
If the ASCO abstract reflects a later, more updated analysis, how is it possible that the NeuVax DFS rate of 96.2% in the ASCO abstract is
higher than the NeuVax DFS rate of 95.9% observed in December?
The DFS rates in the control group are different as well.
Over time, DFS rates must go down, not up. A patient can't have recurrence of disease and then later NOT have recurrence of disease.
Like I said above, I asked Galena for an explanation but the company declined. The discrepancies in the NeuVax data may be cleared up when Galena presents its poster at the ASCO meeting in a little more than week from now. Hopefully, Galena will also disclose 60-month data on all patients in the study, not just the patients who received booster injections.
If you cast aside the inconsistencies noted above, you're still left with DFS rates (or recurrence rates) that seem to strongly favor NeuVax. This is the crux of the argument made by Galena bulls -- the vaccine is training patients' immune system to recognize and attack residual cancer cells, thereby dramatically reducing the chances that breast cancer will recur.
I poked some
big holes in the bulls' theory last month, pointing out that the overall results from the NeuVax phase II study were negative -- no statistically significant difference in DFS was observed between NeuVax-treated patients and the control was observed. Galena was only able to detect positive results by retrospectively data-mining to find small patients subgroups (low-expressing HER-2 tumors and those optimally dosed) where NeuVax allegedly led to significantly higher DFS rates (or lower recurrence rates.)
Now, I've found even more data to support my contention that NeuVax doesn't work: The breast cancer patients treated with NeuVax in the phase II study were much healthier compared to the breast cancer patients funneled into the control group. This imbalance in the baseline patient characteristics easily skewed the DFS/recurrence rate in favor of NeuVax.
This particularly damaging red flag was discovered after inspecting the NeuVax poster presented in December at the San Antonio Breast Cancer Symposium. The poster, "Long-term clinical benefit of adjuvant breast cancer vaccine: 5 year efficacy of E75 with multiple booster innoculations" is available for free download through a
simple registration process on the group's web site.
Search for "E75" in the "Posters2View" section of the 2011 Symposium.
The most important data in the poster are in Table 1, "E75 Demographics," which is also the data that Galena doesn't share with investors. This table describes the baseline characteristics of the 108 patients treated with NeuVax compared to the 79 patients in the study's control arm.
Overall, the table describes a Neuvax patient group that is generally healthier, with less advanced disease, than those in the control group. Some specifics:
Node positive breast cancer: 49.1% in the NeuVax arm versus 55.7% in the control arm. Node positive breast cancer means cancer cells have been detected in the lymph nodes. Although all the patients were disease free prior to entering the NeuVax study, the presence of cancer cells in the lymph nodes means there is a higher chance of breast cancer returning and spreading to other parts of the body.
Tumor size (T2-T4): 34.3% in the NeuVax arm versus 46.2% in the control arm. Breast cancer asessed as T2-T4 is larger and spread wider to tissues like the skin and chest wall near the breast.
HER2/neu overexpression: 31% in the NeuVax arm versus 26.8% in the control arm. HER2 positive breast cancers tend to be more aggressive than other types of breast cancer and are commonly treated with Roche's Herceptin. The difference in HER2 overexpression between NeuVax and control is not that large in the phase II study, but…
(Here's the kicker…)
Prior trastuzumab (Herceptin) therapy: 11.1% in the NeuVax arm versus 3.8% in the control arm.
That's a big difference and could easily explain away the DFS/recurrence trend seems to favor Neuvax in the phase II study. Control-arm patients are sicker, have more aggressive breast cancer and were treated less often with Herceptin, therefore, their breast cancer is recurring at a faster rate.
Galena is conducting a larger phase III study which if done correctly will not have these types of serious imbalances between NeuVax-treated patients and control patients. When the results eventually read out, NeuVax's "benefit" seen in the phase II will likely disappear, as will the vaccine's chance of being approved.
--Written by Adam Feuerstein in Boston.