Antigen Express's AE37 Vaccine at ASCO 2013

Abstracts for the American Society of Clinical Oncology (ASCO) Annual Meeting were released today at 6 pm, ahead of the meeting which will be held May 31 - June 4, 2013 in Chicago, Illinois. Two abstracts featuring AE37 were accepted for poster publication, whith another published in conjunction with the 2013 Annual Meeting, but not presented at the Meeting. While none of the abstracts contain pivotal data, they do illustrate positive trends from studies of AE37 in breast and prostate cancer patients.

Here are the abstracts:

Booster inoculations of the AE37 peptide vaccine enhance immunological responses in a phase II study. Abstract No: 3095

Author(s): Eleftheria A Anastasopoulou, Efi Pappou, Panagiotis Tzonis, Alexandros Ardavanis, Sathibalan Ponniah, Constantin N. Baxevanis, James L. Murray, Michael Papamichail, Sonia A. Perez, George Earl Peoples, Elizabeth Ann Mittendorf; Cancer Immunology and Immunotherapy Center Saint Savas Cancer Hospital, Athens, Greece; Cancer Immunology and Immunotherapy Center, Saint Savas Cancer Hospital, Athens, Greece; Cancer Vaccine Development Program, United States Military Cancer Institute, USUHS, Bethesda, MD; The University of Texas MD Anderson Cancer Center, Houston, TX; Cancer Immunology and Immunotherapy Center, Athens, Greece; San Antonio Military Medical Center, San Antonio, TX

Background: We are conducting a multicenter randomized phase II trial of AE37, the Ii-Key hybrid peptide of HER2 776-790 (AE36). The purpose of the study is to determine if the AE37 vaccine can prevent recurrence in disease-free conventionally treated node-positive (NP) and high-risk node-negative (NN) breast cancer patients at significant risk for recurrence. Since clinical efficacy is anticipated to occur as the result of long lasting memory immune responses induced by vaccination, repeated booster inoculations were scheduled as part of the trial. Here we present data on immune responses in patients who received boosters up to 24 months after completion of the primary vaccination series (PVS).

Methods: The trial is enrolling NP or high-risk NN patients with any degree of HER2 expression (IHC 1-3+ or FISH > 1.2) rendered disease-free following standard of care therapy. The vaccine group (VG) received AE37+GM-CSF and control group (CG) GM-CSF alone in 6 monthly i.d. inoculations followed by boosters administered every 6 months x 4. Immunologic responses were assessed in vivo by dermal reactions at the inoculation site, and in vitro, against the AE36 peptide, with proliferation and IFN-γ ELISPOT assays.

Results: 25 patients in the VG and 23 in the CG have completed their boosters. After the last booster (BRC24), 100%, 54% and 54% in the VG (vs. 9%, 18% and 27% in the CG) responded by dermal reaction, proliferation and IFN-γ ELISPOT, respectively. Mean dermal reactions (orthogonal mean in mm) in vaccinated patients was 25.9±3.13 at completion of the PVS (R6) and increased to 35.47±4.35 at BRC24 (p=0.01). VG patients increased their proliferation response (stimulation index, SI) to AE36 from 0.97±0.046 at baseline (R0) before vaccination to 2.27±0.57 at R6 (p=0.0003) which was maintained until BRC24 (SI 2.21±0,33, p<0.0001). The number of IFN-γ specific spots/106 PBMC increased from 26.88±12.36 at R0 to 40.35±17.02 (p=0.07) at R6, up to 62±16.82 (p=0.0076) at BRC24. Conclusions: Our data demonstrate that AE37 vaccine boosters enhance the immune responses against HER elicited during the PVS, thus sustaining long lasting immunity, a prerequisite for possible clinical efficacy which is currently being evaluated.

Risk factors for development of delayed urticarial reactions in the phase II trial of HER2 peptide vaccines plus GM-CSF versus GM-CSF alone in high-risk breast cancer patients to prevent recurrence Abstract No: 3097

Author(s): Alfred F Trappey, John S. Berry, Timothy J Vreeland, Diane F. Hale, Alan K. Sears, Sathibalan Ponniah, Sonia A. Perez, Guy T. Clifton, Michael Papamichail, Nathan M. Shumway, Elizabeth Ann Mittendorf, George Earl Peoples; Brooke Army Medical Center, San Antonio, TX; Cancer Vaccine Development Program, United States Military Cancer Institute, USUHS, Bethesda, MD; Cancer Immunology and Immunotherapy Center, Saint Savas Cancer Hospital, Athens, Greece; Cancer Immunology and Immunotherapy Center, Athens, Greece; San Antonio Military Medical Center, Fort Sam Houston, TX; The University of Texas MD Anderson Cancer Center, Houston, TX; Department of Surgery, Brooke Army Medical Center, Fort Sam Houston, TX

Background: We are monitoring the incidence of delayed urticarial reactions (DURs) in our phase II trial evaluating adjuvant HER2-specific vaccines (AE37 and GP2) for the prevention of breast cancer recurrence. Here, we characterize DURs and analyze risk factors for their development.

Methods: After completion of standard of care therapy, disease-free node-positive or high-risk node-negative patients (pts) were randomized to receive either a peptide+GM-CSF (VG) or GM-CSF (CG). Pts receive 6 monthly intradermal inoculations during the primary vaccine series (PVS) then four boosters (B) every 6 mos. Immune response is measured by delayed type hypersensitivity (DTH) pre- (R0) and post-PVS (R6) and local reaction (LR) at R1 – R6.

Results: Twenty-four (6.1%) of 393 initiated patients report a DUR; 13 VG (vDUR), and 11 CG (cDUR); vDUR - 9 AE37, 4 GP2. Time to onset of symptoms is 9±5 days (d) and is similar in vDUR/cDUR (p = 0.27). DURs manifest as hives/pruritis in all patients. Average duration of symptoms is 32.6 d ± 8.8 d (no difference in vDUR/cDUR [p = 0.23]). Episodes have resolved with antihistamines or IV/oral steroids. Ten (4 cDUR, 6 vDUR) patients have had recurrent episodes that have resolved similarly. 75% of first episodes occur between R6-B3. For DUR patients v. those who have not had a DUR (noDUR), there are no differences in demographics. DTH response is similar in vDUR pts v. noDUR VG pts (R0- p = 0.34; R6- p=0.40). cDUR pts had a greater DTH response v. CG noDUR pts at R6 (13.2 v 4.7 mm, p=0.01). LRs are greater in DUR pts compared to noDUR pts after the second vaccination (R2 – 66.2 v 48.2 mm, p=0.02). LR for DUR pts decrease and are less than noDUR at R6 (45.4 v 57.4 mm, p=0.09). Relative risk for developing DUR for LR > 100 mm at R2 is 3.49 (1.58-7.68, 95% CI [p=0.004]). At 29.9 months median follow-up, there have been no recurrences in VG and CG DUR v. 75.9% DFS for noDUR (p=0.05).

Conclusions: DURs occur infrequently and without long-term sequelae. Pts at risk for developing DUR are identified early in the vaccine series using LR. Robust immune response in DUR may explain the survival benefit demonstrated here.

The following is the publish only abstract:

Effect of immunization with Ii-key modified HER2 (776-790) peptide vaccine (AE37) on immunologic responses in prostate cancer patients.

Author(s): Sonia A. Perez, Eleftheria Anastasopoulou, Efi Pappou, Panagiotis Tzonis, Stratos Bisias, Anastasios Thanos, Eric von Hofe, Michael Papamichail, Constantin N. Baxevanis; Cancer Immunology and Immunotherapy Center, Saint Savas Cancer Hospital, Athens, Greece; Antigen Express, Worcester, MA

Background: We have shown that the AE37 vaccine (Ii-Key modified HER2(776-790) peptide) is safe and induces HER2/neu–specific cellular immune responses in patients with prostate cancer (Perez SA et al Clin. Cancer Res. 2010, 16:3495). We now present data from 4-year immunological assessments of prostate cancer patients who received AE37.

Methods: Seventeen patients in a phase I study were given 6 doses of AE37 at monthly intervals and one additional dose a year after initiating treatment. Immunological testing to assess active versus suppressive immunity was conducted one month (intermediate-term immunomonitoring [ITI]) and 3 years (long-term immunomonitoring [LTI]) after the final dose of AE37. ELISPOT and proliferation assays were conducted to assess cytokine secretion and mitogenic response to antigen. DTH reactions were measured to assess in vivo immune response to antigen. All assays were conducted using native HER2(776-790) peptide (AE36). The percent Treg cells and ng/ml TGFβ were determined as markers for immune suppression.

Results: Neither ELISPOT nor proliferation assays were statistically different at LTI compared to ITI. While clearly above pre-vaccine responses, the drop in DTH was statistically significant (p < 0.05). Similarly, the increase in Treg cells and circulating TGFβ was also statistically significant. An increase of >200 % in PSA-doubling time at any point during the study was observed in 6/17 patients, with 3 retaining this effect to 5 years.

Conclusions: AE37 generates immunological memory associated with possible clinical efficacy in spite of Tregs and TGF-β levels returning at 4 years after being decreased for up to 6 months after initial AE37 vaccination. These results support further randomized testing of the AE37 vaccine.

The publish only abstract is interesting. We know from an earlier publication (see here) that nine of the subjects who completed the vaccine series were stage IV metastatic (later stage) patients with bone metastases. In that earlier publication, the researchers noted,

The maximum increase of specific IFN-γ–producing T cells in response to vaccination with AE37, detected by ELISPOT and expressed as mean fold increase from baseline levels, was higher in stage II-III and castrate-sensitive patients compared with stage IV and castrate-resistant patients, respectively, although this difference was not statistically significant. Similarly, DTH responses to the vaccine, determined as the difference of post vac minus baseline DTH, were statistically significantly lower in stage IV patients.

In that report, the researchers conclude that,

In conclusion, the use of the AE37 immunotherapeutic vaccine is a novel strategy for managing patients with prostate cancer. This clinical trial shows that the vaccine is safe and immunologically active. However, proof of clinical benefit will require a phase II trial in a homogeneous group of patients with less extensive disease, including disease-free patients at high risk of recurrence.

Therefore, it appears reasonable to assume that results for the Phase I study would be even more positive if the appropriate traget population had been identified, with booster innoculations to prolong the effectiveness of the vaccine. The incease of >200 % in PSA-doubling time at any point during the study for 6/17 patients is remarkable, and since this earlier Phaser I study was initiated Antigen Express has learned much about the vaccine. Booster series have been added to the breast cancer Phase II, with a targeting of lower HER2 expressing early stage subjects.

As we can see with the first ASCO abtract, titled "Booster inoculations of the AE37 peptide vaccine enhance immunological responses in a phase II study", Antigen Express is on the right tract in developing AE37. The prostate cancer Phase I illustrates that AE37 stimulates long lasting memory, and the new booster program can help add to the desired effect. The second ASCO abstract,titled "Risk factors for development of delayed urticarial reactions in the phase II trial of HER2 peptide vaccines plus GM-CSF versus GM-CSF alone in high-risk breast cancer patients to prevent recurrence", highlights the strong safety profile of AE37/GM-CSF + booster, so all appears on track, even if these abstracts don't yet outline final results of the ongoing Phase II study in early stage HER2 breast cancer patients, which may be needed to lift GNBT's dreadful stock. Those final results may come later this year.

Click on the abstract titles to view the content at ASCO's 3013 Annual Meeting website.

Two Abstracts Pertaining to the AE37 HER2/neu Vaccine Accepted as Poster Presentations at ASCO 2013

Two abstracts pertaining to Antigen Express' AE37 Her2/neu vaccine have been accepted for poster presentations at the 2013 American Society of Clinical Oncology ("ASCO") Annual Meeting. The annual ASCO meeting is being held in Chicago, Illinois from May 31 through June 4, 2013.

The abstract titles, with the name of the lead author, were revealed today with the launch of the meeting's iplanner. Here is the available information:

Abstract #3095

Booster inoculations of the AE37 peptide vaccine enhance immunological responses in a phase II study.

Eleftheria A. Anastasopoulou

Abstract #3097

Risk factors for development of delayed urticarial reactions in the phase II trial of HER2 peptide vaccines plus GM-CSF versus GM-CSF alone in high-risk breast cancer patients to prevent recurrence.

Alfred F. Trappey, MD

The iplanner is available for review here.

Army Surgeons Present New Research on Cancer Vaccine

The following press release was issued by the U.S. Army Medical Department on October 3rd, 2012:

CHICAGO, Oct. 3, 2012 – Yesterday U.S. Army surgeons exhibited new research findings at the American College of Surgeons Clinical Congress.

The poster presentation titled, "Assessment of Disease Features and Immune Response in Breast Cancer Patients with Recurrence after Receiving AE37, a HER2 Peptide Vaccine," outlined outcomes of injecting AE37, a HER-2 derived vaccine, in breast cancer survivors following completion of standard therapy. Those who received injections of AE37 were more likely to survive disease-free than the control group.

Meanwhile, the poster presentation titled, "A NSQIP Evaluation of Practice Patterns and Outcomes Following Surgery for Anorectal Abscess and Fistula in Patients with and without Crohn's Disease," showed patients with Crohn's Disease (CD) – a form of inflammatory bowel disease – had more aggressive anorectal abscess and fistula disease and suffered more complications following emergency surgery than patients who did not have CD.

AE37 breast cancer vaccine creates robust immunologic response in cancer survivors

The poster "Assessment of Disease Features and Immune Response in Breast Cancer Patients with Recurrence after Receiving AE37, a HER2 Peptide Vaccine," showed after completing standard treatment, breast cancer survivors who received injections of AE37 with granulocyte-macrophage colony-stimulating factor (GM-CSF) – an immune stimulant – were more likely to survive five years disease-free than a control group that received GM-CSF alone. AE37 works by stimulating the immune system to recognize and target for destruction a protein called HER2 that is expressed at some level by most breast cancer cells.

While AE37 did not prevent recurrence in all patients, it provoked an immunologic response in patients across the board, including survivors at high risk of recurrence, those with the hard-to-treat "triple negative" form of breast cancer and those with lower levels of HER2 expression. "Patients with a lower level of expressed HER2 protein, who wouldn't be eligible for the HER2-binding antibody, trastuzumab (Herceptin), had a survival rate of more than 88 percent, compared to 70 percent in the control group," said U.S. Army Capt. John Berry, MD, a research associate. "The vaccine may have benefited patients with less aggressive cancers."

Study director Col. George E. Peoples, M.D., explained how the Cancer Vaccine Development Program differs from other groups investigating cancer vaccines. "Our program was one of the first to enroll cancer survivors with healthy immune systems rather than focus on people with end-stage, metastatic cancer. Our goal is to increase health and survivorship in this group, including specifically those with a high risk of cancer recurrence."

This study is part of an ongoing prospective, multi-center, randomized, single-blinded phase IIb adjuvant therapy trial. AE37 was co-developed by the Cancer Vaccine Development Program, housed at Brooke Army Medical Center in San Antonio, Texas.

Capt. Diane F. Hale, M.D., Sonia Perez, Ph.D., Capt. Timothy Vreeland, M.D., Capt. Dabney Raetasha, M.D., Michael Papamichail, M.D., Ph.D., Maj. Guy T. Clifton, M.D., Capt. Alan Sears, M.D., Sathibalan Ponniah Ph.D., and Elizabeth A. Mittendorf, M.D., FACS, also participated in the study.

Generex's AE37 Vaccine Press Release Appears Off Target

I'm someone so clumsy that I'd be better off throwing an apple at an arrow, as opposed to an attempt at shooting an arrow at an apple. There's a better chance that I'd shoot the arrow at my foot, or straight up in the air, so I'd only split my head. The wiser move is to simply eat the apple, and forget the arrow. Generex, and their wholly owned subsidiary Antigen Express, appear equally clumsy when it comes to writing press releases detailing the latest data that researchers are presenting for their novel AE37 HER2/neu peptide vaccine. I'm joking a bit, so I hope the good folks at Generex have a sense of humor. Yet, their follies in this area are true.

The latest example of the reporting of interim efficacy results for AE37 in a company press release that are actually lower than the lead researcher's findings came a few hours ago. Here's a quick look. The following sentence is from Generex's press release dated today, where they provide details of a study abstract that will be presented at the ASCO Breast Cancer Symposium this Friday:

While the study showed an overall reduction of 42% in the risk of relapse in all patients of the study who received the vaccine, the reduction in the risk of relapse was 66% in patients with low expression of the HER2 oncoprotein who were classified as having triple negative breast cancer.

That's impressive data, although the actual results are even better. The lead author of the study is Dr Elizabeth Mittendorf from MD Anderson. The following two sentences are from the study abstract:

"After a median follow-up of 22.3 months, the disease-free survival (DFS) rate in the VG is 90.3% vs 81.1% in the CG (p=.46), a 49% risk reduction."

"The DFS rate in the VG of TNBC patients is 83.3% vs 47.6% in the CG (p=.23), a 68% risk reduction."

Generex reports that there was a 42% risk reduction for relapse in all patients who received the vaccine (VG) in the latest interim look at the ongoing study, but the true risk reduction as stated in the abstract is 49%. Generex also reports that there was a 66% risk reduction for relapse in subjects classified as having triple negative breast cancer (TNBC), but the true risk reduction as stated in the abstract is 68%. Here's a link to the press release, and a link to the abstract.

In June, during the ASCO Annual Meeting, Generex's AE37 vaccine was the topic of discussion in a podium presentation titled "From bench to bedside: The use of the li-Key technology to improve helper peptides for clinical use in cancer vaccines". The report highlights earlier interim results for the same ongoing study as discussed today. At the time, Generex issued a press release informing of the presentation, and the following sentence described key data:

With a median follow-up of 22 months in breast cancer patients, Kaplan Meier projections estimate recurrence rates of 10% in vaccinated patients versus 17% in the control group, a risk reduction of 41%.

Once again, that's impressive data. However, Generex also misreported the true findings. The lead author of this report is Dr Tim Vreeland from the San Antonio Military Medical Center. The following sentence reveals the actual data from his presentation:

With a median f/u of 22 months, Kaplan Meier projections estimate recurrence rates of 10.3% in the VG compared to 18% in the CG; a 43% risk reduction

Generex reported that there was a 41% risk reduction for relapse in all patients who received the vaccine up to that time period, with recurrence rates of 10% in the AE37 group vs. 17% in the control group. Dr Vreeland actually reported a 43% risk reduction, with a relapse rate of 10.3% in the AE37 group vs. 18% in the control group. Here's a link to Generex's press release from June, and a link to the actual abstract.

If we go back a little further in time, say to 2009, we may recall this press release from Generex that came one day after an errant corporate update for this same Phase II study. This press release came on the heels of the first look at early efficacy findings, as were presented at the San Antonio Breast Cancer Symposium in December 2009:

Generex Clarifies Previous Announcement of Breast Cancer Study Interim Results

WORCESTER, Mass., Dec 15, 2009 (GlobeNewswire via COMTEX News Network) -- On December 14, 2009, Generex Biotechnology Corporation (Nasdaq:GNBT) (www.generex.com) issued a press release announcing the presentation of interim results from a Phase II efficacy study of a novel immunotherapeutic vaccine being developed by its wholly-owned subsidiary, Antigen Express, Inc. (www.antigenexpress.com), at the 32nd Annual San Antonio Breast Cancer Symposium (www.sabcs.org).

That press release stated that "only half the number of patients in the treatment arm of the study relapsed compared to those not receiving the vaccine," and that "the results presented at the conference were those observed in patients 13.5 months after treatment." Those statements were incorrect. In fact, as COL George Peoples, MD reported to the symposium, at a median follow-up of 13 months, there were NO relapses in patients receiving the AE37 immunotherapeutic vaccine for breast cancer (0 of 49 patients) while relapses were observed in the control group (5 of 71 patients).

The ultimate goal of the study is to demonstrate that, after a follow-up period of 24 months, the relapse rate in the AE37 group of the study is less than half the relapse rate in the control group. The interim results of this study reported by COL Peoples clearly show that the study is on track to achieve that positive endpoint.

Putting 2009 aside, if we just went with the recent information provided by Generex's press releases, we would assess that the study is going well, with a risk reduction of relapse for all subjects staying relatively even, improving from 41% to 42%, as additional subjects are enrolled into the study. From the abstracts, we can see that the risk reduction was factored at a higher 43% in June, and has since improved to 49%.

What's the difference between a 42% risk reduction in relapse vs. 49%? The difference is an extra few early stage breast cancer patients who are participants in this remarkable study that will continue to lead healthy lives, all because Generex and Antigen Express have done an extraordinary job in creating a revolutionary cancer vaccine, even if they struggle with media relations. Generex and Antigen Express may trip on a pebble, such as writing a press release, yet they appear ready to move what was thought to be the toughest of all mountains, CURING CANCER!