Sensitivity of Undifferentiated, High-TCR Density CD8+ Cells to Methylene Groups Appended to Tumor Antigen Determines Their Differentiation or Death

Integrity of plasma DNA is inversely correlated with vaccine-induced antitumor immunity in ovarian cancer patients

Cancer immunotherapy including vaccine therapy is a promising modality for cancer treatment, but few patients show its clinical benefits currently. The identification of biomarkers that can identify patients who will benefit from cancer immunotherapy is thus important. Here, we investigated the potential utility of the circulating cell-free DNA (cfDNA) integrity—a ratio of necrotic cell-derived, longer DNA fragments versus apoptotic cell-derived shorter fragments of Alu gene—as a biomarker of vaccine therapy for patients with ovarian cancer. We analyzed plasma samples from 39 patients with advanced or recurrent ovarian cancer enrolled in clinical trials for personalized peptide vaccinations. We observed that (1) the cfDNA integrity was decreased after the first cycle of vaccination, and (2) the decreased levels of cfDNA integrity were correlated with vaccine-induced immune responses; i.e., decreased cfDNA integrity was observed in 91.7% and 59.3% of the IgG-positive and negative patients, respectively (p = 0.0445). Similarly, decreased cfDNA integrity was observed in 92.9% and 56.0% of CTL response-positive and negative patients, respectively (p = 0.0283). These results suggest that the circulating cfDNA integrity is a possible biomarker for cancer vaccine therapy.

Final analysis of a phase I/IIa trial of the folate-binding protein-derived E39 peptide vaccine to prevent recurrence in ovarian and endometrial cancer patients

BACKGROUND

E39, an HLA-A2-restricted, immunogenic peptide derived from the folate-binding protein (FBP), is overexpressed in multiple malignancies. We conducted a phase I/IIa trial of the E39 + GM-CSF vaccine with booster inoculations of either E39 or E39' (an attenuated version of E39) to prevent recurrences in disease-free endometrial and ovarian cancer patients(pts). Here, we present the final 24-month landmark analysis.

PATIENTS AND METHODS

HLA-A2 + patients receiving E39 + GM-CSF were included in the vaccine group (VG), and HLA-A2- pts (or HLA-A2 + patients refusing vaccine) were followed as the control group (CG). VG group received 6 monthly inoculations as the primary vaccine series (PVS) and were randomized to receive either E39 or E39' booster inoculations. Demographic, safety, immunologic, and disease-free survival (DFS) data were collected and evaluated.

RESULTS

Fifty-one patients were enrolled; 29 in the VG and 22 in the CG. Fourteen patients received <1000 μg and 15 received 1000 μg of E39. There were no clinicopathologic differences between VG and CG or between dose groups. E39 was well tolerated. At the 24 months landmark, DFS was 55.5% (VG) vs 40.0% (CG), P = 0.339. Patients receiving 1000 μg and boosted patients also showed improved DFS (P < 0.03). DFS was improved in the 1000 μg group after treatment of primary disease (90.0% vs CG:42.9%, P = 0.007), but not in recurrent patients. In low-FBP expressing patients, DFS was 100.0% (1000 μg), 50.0% (<1000 μg), and 25.0% (CG), P = 0.029.

CONCLUSIONS

This phase I/IIa trial reveals that E39 + GM-CSF is safe and may be effective in preventing recurrence in high-risk ovarian and endometrial cancer when optimally dosed (1000 μg) to FBP low patients being treated for primary disease.

A phase I/IIa study of the mRNA-based cancer immunotherapy CV9201 in patients with stage IIIB/IV non-small cell lung cancer

CV9201 is an RNActive®-based cancer immunotherapy encoding five non-small cell lung cancer-antigens: New York esophageal squamous cell carcinoma-1, melanoma antigen family C1/C2, survivin, and trophoblast glycoprotein. In a phase I/IIa dose-escalation trial, 46 patients with locally advanced (n = 7) or metastatic (n = 39) NSCLC and at least stable disease after first-line treatment received five intradermal CV9201 injections (400-1600 µg of mRNA). The primary objective of the trial was to assess safety. Secondary objectives included assessment of antibody and ex vivo T cell responses against the five antigens, and changes in immune cell populations. All CV9201 dose levels were well-tolerated and the recommended dose for phase IIa was 1600 µg. Most AEs were mild-to-moderate injection site reactions and flu-like symptoms. Three (7%) patients had grade 3 related AEs. No related grade 4/5 or related serious AEs occurred. In phase IIa, antigen-specific immune responses against ≥ 1 antigen were detected in 63% of evaluable patients after treatment. The frequency of activated IgD+CD38hi B cells increased > twofold in 18/30 (60%) evaluable patients. 9/29 (31%) evaluable patients in phase IIa had stable disease and 20/29 (69%) had progressive disease. Median progression-free and overall survival were 5.0 months (95% CI 1.8-6.3) and 10.8 months (8.1-16.7) from first administration, respectively. Two- and 3-year survival rates were 26.7% and 20.7%, respectively. CV9201 was well-tolerated and immune responses could be detected after treatment supporting further clinical investigation.

Inhibition of GSK3 and MEK induced cancer stem cell generation via the Wnt and MEK signaling pathways

Cancer stem cells (CSCs) are considered to be tumor-initiating cells, responsible for tumor invasive growth and dissemination to distant organ sites. Typically, radiation treatment and chemotherapy should target CSCs. However, current research investigating CSCs is impeded by the difficulty of isolating pure CSCs and maintaining them in vitro. In the present study, the synergistic inhibition of glycogen synthase kinase 3 and mitogen-activated protein kinase kinase using small molecules, CHIR99021 and PD184352, efficiently generated CSCs from immortalized human mammary epithelial cells (HMLEs) and resulted in the acquisition of mesenchymal traits and the expression of epithelial-mesenchymal transition markers. The cell proliferation, invasion and migration of HMLE cells were significantly promoted by CHIR99021 and PD184352 (P<0.05). Furthermore, the cell cycle was shifted from the G0/G1 phase to the G2/M phase, and the apoptotic rate was suppressed in HMLE cells following treatment with CHIR99021 and PD184352. Compared with control group, the stimulated cells exhibited an increased ability to form mammospheres and regenerate a tumor. In addition to these properties, the induced cells also exhibited notable chemotherapy resistance. In vivo, the treatment of cells with CHIR99021 and PD184352 promoted the growth of HMLE-engrafted tumor types. These results provide a practical strategy for the generation of CSCs using small molecules in vitro, which provides a cell resource that may be used for drug screening. Additionally, the present results additionally highlighted the synergistic functions of Wnt and mitogen-activated protein kinase kinase signaling pathways in tumorigenesis.

Evaluation of Attenuated Tumor Antigens and the Implications for Peptide-Based Cancer Vaccine Development

INTRODUCTION: Peptide vaccines offer anti-tumor efficacy with very low toxicity. However, repeat stimulation with an immunogenic peptide leads to activation induced cell death (AICD), decreasing efficacy. We engineered variants of an immunogenic peptide (E39) and tested their ability to induce a robust, sustainable immune response.

METHODS: Multiple variants of E39 were created by exchanging 1 or 2 amino acids. We tested the PBMC proliferation, cytokine production and cytolytic activity induced by each variant peptide. RESULTS: Repeated stimulation with E39 likely led to in vitro AICD, while stimulation with E39' led to T-cell proliferation with less evidence of AICD, modest cytokine production and high CTL activity. CONCLUSIONS: E39' appears to be the optimal variant of E39 for inducing effective long-term immunity.

Feasibility study of personalized peptide vaccination for recurrent ovarian cancer patients

CONTEXT

To develop a personalized peptide vaccine (PPV) for recurrent ovarian cancer patients and evaluate its efficacy from the point of view of overall survival (OS), Phase II study of PPV was performed.

PATIENTS AND METHODS

Forty-two patients, 17 with platinum-sensitive and 25 with platinum-resistant recurrent ovarian cancer, were enrolled in this study and received a maximum of four peptides based on HLA-A types and IgG responses to the peptides in pre-vaccination plasma.

RESULTS

Expression of 13 of the 15 parental tumor-associated antigens encoding the vaccine peptides, with the two prostate-related antigens being the exceptions, was confirmed in the ovarian cancer tissues. No vaccine-related systemic severe adverse events were observed in any patients. Boosting of cytotoxic T lymphocytes or IgG responses specific for the peptides used for vaccination was observed in 18 or 13 of 42 cases at 6th vaccination, and 19 or 29 of 30 cases at 12th vaccination, respectively. The median survival time (MST) values of the platinum-sensitive- and platinum-resistant recurrent cases were 39.3 and 16.2 months, respectively. The MST of PPV monotherapy or PPV in combination with any chemotherapy during the 1st to 12th vaccination of platinum-sensitive cases was 39.3 or 32.2 months, and that of platinum-resistant cases was 16.8 or 16.1 months, respectively. Importantly, lymphocyte frequency and epitope spreading were significantly prognostic of OS.

DISCUSSION AND CONCLUSION

Because of the safety and possible prolongation of OS, a clinical trial of PPV without chemotherapy during the 1st to 12th vaccination in recurrent ovarian cancer patients is merited.

Synthesis of rotenoid derivatives with cytotoxic and topoisomerase II inhibitory activities

6-Deoxyclitoriacetal (1) and a series of 11 further derivatives of it (2-12) were synthesized and evaluated for their cytotoxic and topoisomerase IIα inhibitory activities. Compounds bearing epoxide (2), morpholine (6) and benzylamine (10) moieties showed promising in vitro cytotoxic activities against four cancer cell lines, with IC(50) values ranging from 0.38 to 0.73 μM. These three compounds also strongly inhibited topoisomerase II activity at 68.3-93.5% and showed a moderately high DNA intercalating property.

Created Gli-1 duplex short-RNA (i-Gli-RNA) eliminates CD44 Hi progenitors of taxol-resistant ovarian cancer cells

Notch and Hedgehog activate cell-cycle progression of adult and cancer stem cells. Notch is activated by DLL and Jag presents on neighboring cells. We investigated the effects of density of the Notch-activating ligand, Jag-1, and targeting Gli-1, in activation of division of paclitaxel/taxol-resistant, (PTX Res) ovarian cancer cells SKOV3 (SKOV3). We used the specific gamma-presenilin inhibitor, DAPT, to identify the specificity of activating signals for Notch-1 and created 'butterfly-duplex-3548-Gli-1-inhibitory RNA' (i-Gli-1.RNA) to inhibit cell division. To accurately quantify kinetics of division, the expression of CD44 and CD24 was determined in each gated population of divided cells. CD44 High proliferated when activated by Jag-1 Low and poorly when activated by Jag-1 High. DAPT inhibited proliferation of cells activated by Jag-1 Low, and increased proliferation of cells activated by Jag-1 High. Only 5-10% of cells activated by Jag-1 High and Jag-1 Low divided fast, polynomial, and symmetric. i-Gli-1.RNA eliminated more than 50% of the small CD44 High/CD24 Neg cells in divisions 3 and 4. This effect appeared specific compared with cells transfected with negative control siRNA. i-Gli-1.RNA had no effect on large CD44 High/CD24 Neg cells, but inhibited the population of CD44 High/CD24 Low cells. Expansion of CD44 High inversely correlated with Jag-1 density on activating autologous tumor and fibrosarcoma cells. Created i-RNAs may decrease the resting CSC pool. Notch and Gli-1 signals play an important role in proliferation/division and survival of cancer stem cells. Targeting Notch-1 through its enhancer Gl-1, should be significant for novel treatments to eliminate taxol-resistant cancer stem cells (CSC). i.Gli-1 RNA should be more effective if used together with Taxol.

Results of the first phase 1 clinical trial of the HER-2/neu peptide (GP2) vaccine in disease-free breast cancer patients: United States Military Cancer Institute Clinical Trials Group Study I-04

BACKGROUND

HER-2/neu, overexpressed in breast cancer, is a source of immunogenic peptides that include GP2 and E75. Phase 2 testing of E75 as an adjuvant vaccine has suggested a clinical benefit. GP2, derived from the transmembrane portion of HER-2/neu, has differing binding characteristics and may be more immunogenic than E75. Results of the first phase 1 trial of GP2 peptide vaccine are presented.

METHODS

Disease-free, lymph node-negative, human leukocyte antigen (HLA)-A2(+) breast cancer patients were enrolled. This dose escalation trial included 4 groups to determine safety and optimal GP2 peptide/granulocyte-macrophage colony-stimulating factor (GM-CSF) dose. Toxicities were monitored. Immunologic response was assessed ex vivo via the HLA-A2:immunoglobulin dimer assay to detect GP2-specific CD8(+) T cells (and E75-specific CD8(+) T cells to assess epitope spreading) and in vivo via delayed type hypersensitivity (DTH) reaction (medians/ranges).

RESULTS

Eighteen patients were enrolled. All toxicities were grade < or =2. Eight (88.9%) of 9 patients in the first 3 dose groups required GM-CSF dose reductions for local reactions > or =100 mm or grade > or =2 systemic toxicity. GM-CSF dose was reduced to 125 microg for the final dose group. All patients responded immunologically ex vivo (GP2-specific CD8(+) T cells from prevaccination to maximum, 0.4% [0.0%-2.0%] to 1.1% [0.4%-3.6%], P < .001) and in vivo (GP2 pre- to postvaccination DTH, 0 mm [0.0-19.5 mm] to 27.5 mm [0.0-114.5 mm, P < .001). E75-specific CD8(+) T cells also increased in response to GP2 from prevaccination to maximum (0.8% [0.0%-2.41%] to 1.6% [0.86%-3.72%], P < .001).

CONCLUSIONS

The GP2 peptide vaccine appears safe and well tolerated with minimal local/systemic toxicity. GP2 elicited HER-2/neu-specific immune responses, including epitope spreading, in high-risk, lymph node-negative breast cancer patients. These findings support further investigation of the GP2 vaccine for the prevention of breast cancer recurrence.

Breast cancer cells expressing stem cell markers CD44+ CD24 lo are eliminated by Numb-1 peptide-activated T cells

Cancer stem cells (CSC) are resistant to chemo- and radiotherapy. To eliminate cells with phenotypic markers of CSC-like we characterized: (1) expression of CD44, CD24, CD133 and MIC-A/B (NKG2 receptors) in breast (MCF7) and ovarian (SK-OV-3) cells resistant to gemcitabine (GEM), paclitaxel (PTX) and 5-fluorouracil (5-FU) and (2) their elimination by Numb- and Notch-peptide activated CTL. The number of cells in all populations with the luminal CSC phenotype [epithelial specific antigen(+) (ESA) CD44(hi) CD24(lo), CD44(hi) CD133(+), and CD133(+) CD24(lo)] increased in drug-resistant MCF7 and SK-OV-3 cells. Similarly, the number of cells with expressed MIC-A/B increased 4 times in drug-resistant tumor cells compared with drug-sensitive cells. GEM(Res) MCF7 cells had lower levels of the Notch-1-extracellular domain (NECD) and Notch trans-membrane intracellular domain (TMIC) than GEM(Sens) MCF7. The levels of Numb, and Numb-L-[P]-Ser(265) were similar in GEM(Res) and GEM(Sens) MCF7 cells. Only the levels of Numb-L (long)-Ser(295) decreased slightly. This finding suggests that Notch-1 cleavage to TMIC is inhibited in GEM(Res) MCF7 cells. PBMC activated by natural immunogenic peptides Notch-1 (2112-2120) and Numb-1 (87-95) eliminated NICD(positive), CD24(hi) CD24(lo) MCF7 cells. It is likely that the immunogenic Numb-1 peptide in MCF7 cells originated from Numb, [P]-lated by an unknown kinase, because staurosporine but not wortmannin and MAPK-inhibitors decreased peptide presentation. Numb and Notch are antagonistic proteins which degrade each other to stop and activate cell proliferation, respectively. Their peptides are presented alternatively. Targeting both antagonistic proteins should be useful to prevent metastases in patients whose tumors are resistant to conventional treatments.

Taxol Increases the Amount and T Cell–Activating Ability of Self-Immune Stimulatory Multimolecular Complexes Found in Ovarian Cancer Cells

It has been proposed that chemotherapy enhances tumor antigen (TA)-specific immunity. The molecular form of TA from ovarian tumor that activates cellular immunity is unknown. We report here identification of a novel molecular form of immunogenic TA for CD8(+) cells named self-immune stimulatory multimolecular complexes (ISMMC). ISMMC consist of a molecular complex of polyosome/ribosome-bound ubiquitinated nascent HER-2 polypeptides. This complex is chaperoned by heat shock protein Gp96, which mediates ISMMC uptake by antigen-presenting cells through the scavenger receptor CD91. RNAs in ISMMC stimulate immature dendritic cells to secrete interleukin 12 and induce IFN-gamma in peripheral blood mononuclear cells. ISMMC dissociate, retrotranslocate from the lysosome to cytoplasm, and are processed to peptides by the proteasome. At subpharmacologic doses, Taxol increased the amount of ISMMC by three to four times and modified their composition by inducing the attachment of cochaperones of HSP70, such as the mitotic-phase phosphoprotein 11J. On a total protein basis, Taxol induced ISMMC, expanded more CD8(+) cells, activated more CD56(+) NKG2D(+) cells to produce IFN-gamma, and were more potent inducers of high T-cell receptor density Perforin(+) cells than native ISMMC and peptide E75. Elucidation of the composition of ISMMC and identification of adducts formed by Taxol should be important for developing molecular cancer vaccines.

Evaluation of the HER2/neu-derived peptide GP2 for use in a peptide-based breast cancer vaccine trial

BACKGROUND

E75 and GP2 are human leukocyte antigen (HLA)-A2-restricted immunogenic peptides derived from the HER2/neu protein. In a E75 peptide-based vaccine trial, preexisting immunity and epitope spreading to GP2 was detected. The purpose of this study was to further investigate GP2 for potential use in vaccination strategies. Importantly, a naturally occurring polymorphism (I-->V at position 2, 2VGP2) associated with increased breast cancer risk was addressed.

METHODS

Prevaccination peripheral blood samples (PBMC) from HLA-A2 breast cancer patients and CD8+ T cells from HLA-A2 healthy donors were stimulated with autologous dendritic cells (DC) pulsed with GP2 and tested in standard cytotoxicity assays with HER2/neu+ tumor cells or GP2- or 2VGP2-loaded T2 targets. Additional cytotoxicity experiments used effectors stimulated with DC pulsed with E75, GP2, or the combination of E75+GP2.

RESULTS

GP2-stimulated prevaccination PBMC from 28 patients demonstrated killing of MCF-7, SKOV3-A2, and the HLA-A2- control target SKOV3 of 28.8+/-3.7% (P<.01), 29.5+/-4.0% (P<.01), and 16.9+/-2.7%, respectively. When compared with E75, GP2-stimulated CD8+ T cells lysed HER2/neu+ targets at 43.8+/-5.2% versus 44.2+/-5.7% for E75 (P=.87). When combined, an additive effect was noted with 58.6+/-5.4% lysis (P=.05). GP2-stimulated CD8+ T cells specifically recognized both GP2-loaded (19.6+/-5.7%) and 2VGP2-loaded T2 targets (17.7+/-5.2%).

CONCLUSIONS

GP2 is a clinically relevant HER2/neu-derived peptide with immunogenicity comparable to that of E75. Importantly, GP2-specific effectors recognize 2VGP2-expressing targets; therefore, a GP2 vaccine should be effective in patients carrying this polymorphism. GP2 may be most beneficial used in a multiepitope vaccine.