The incidence and burden of injury in male adolescent community rugby union in Australia

OBJECTIVES

To describe the incidence, location, mechanism and burden of injury in community male adolescent rugby.

METHODS

A prospective cohort injury surveillance study using sports trainers to record 'any physical complaint' over three seasons (2018/2019/2021) in 979 U13-U17 community male rugby union players.

RESULTS

One hundred and fifty-two time-loss injuries (27.6/1000 hours) with an associated burden of 2313 days (419.7 days/1000 hours), 169 non-time loss medical attention (30.1/1000 hours) and 813 physical complaints (147.5/1000 hours) were recorded from 5511.7 exposure hours (matches 3932.5 hours, training 1579.2 hours). Time-loss injury incidence was highest in U16 (45/1000 hours) and lowest in U17 (16.6/1000 hours), with U17 significantly lower than U16 and U15 age-grades (p < 0.05). Injury burden was greatest in U13 (561.4 days/1000 hours), and significantly higher than U15 and U17 (p < 0.05). Collectively, injury incidence was greatest for the head/neck (11.8/1000 hours), bruise/contusions were most common (8.7/1000 hours) and concussion (4.5/1000 hours) accounted for the greatest injury burden (102 days/1000 hours). Being tackled was the most observed injury mechanism (10.0/1000 hours). Forwards had significantly higher incidence in mild injury (p < 0.01). The total burden (p < 0.001) associated with mild (p < 0.001) and moderate injuries (p < 0.001) was significantly higher in forwards, as was the burden of being tackled (p < 0.001), collisions (p < 0.001), trunk (p < 0.001) and lower limb (p < 0.01) injury locations. In contrast, ruck-related injury burden was greater in backs (p < 0.001).

CONCLUSION

This study showed age-grade and positional differences in incidence and burden of injury in community adolescent rugby union. The rate of non-time loss relative to time-loss injury and muscle strain injury in U13-U14s suggests further research into injury risk and maturation in rugby is needed.

The influence of harvest method on dendritic cell function and clinical outcomes in a randomized trial of a dendritic cell vaccine to prevent recurrences in high-risk melanoma

9548

Background: A randomized, double-blind, placebo-controlled phase IIb trial of the tumor lysate, particle loaded, dendritic cell (TLPLDC) vaccine was conducted to prevent recurrence in patients (pts) with resected stage III/IV melanoma. Two methods for dendritic cell (DC) harvest were used for vaccine production, including no pretreatment or pretreatment with granulocyte-colony stimulating factor (G-CSF) in an attempt to reduce blood draw volumes. This analysis investigates differences in clinical outcomes and RNA gene expression between these DC harvest methods for TLPLDC vaccine creation. Methods: The TLPLDC vaccine is created by loading autologous tumor lysate into yeast cell wall particles (YCWPs) and exposing them to phagocytosis by DCs. By investigator/pt choice, pts had 120mL of blood drawn for DC harvest, or pts received 300μg of G-CSF for pre-DC mobilization and a 50-70 mL blood draw 24-48 hours later. Total vaccine production time was 72 hrs. Pts were randomized 2:1 to receive TLPLDC or placebo (DCs exposed to empty YCWPs). 1-1.5 x10^6 cells/dose were injected intradermally at 0, 1, 2, 6, 12, and 18 months. Differences in disease free survival (DFS) and overall survival (OS) were evaluated by Kaplan Meier analysis between pts who did not receive pretreatment (TLPLDC), pts who did receive pretreatment with G-CSF (TLPLDC+G), and pts receiving placebo. RNA-seq analysis was performed on the total RNA of pts’ prepared TLPLDC vaccines to assess gene expression. Relative RNA expression (RRE) was compared between TLPLDC and TLPLDC+G. Results: As previously reported, 144 pts were randomized: 103 received TLPLDC (46 TLPLDC, 57 TLPLDC+G) and 41 received placebo. There were no significant clinicopathologic or treatment differences between the three treatment arms. Survival was significantly improved in TLPLDC compared to TLPLDC+G or placebo, including 36-month OS (92.9% vs 62.8% vs 72.3% respectively, p = 0.022) and DFS (51.8% vs 23.4% vs 27.1%, p = 0.027). When compared to TLPLDC+G (n = 3) vaccine, RNA-seq from TLPLDC vaccine (n = 3) showed upregulation of genes associated with DC maturation, including HLA-DMB (RRE: 3.60), IFIT1 (3.38), CD27 (3.26), IFI44L (3.24), MX1 (2.96), HLA-DQA1 (2.67), HLA-DRA (2.40), CD49D (2.34) and CD74 (2.09), while downregulated genes were associated with DC suppression or immaturity including SERPINA1 (RRE:7.8), TLR2 (6.65), CCR1 (5.11), IL10 (4.19), CD93 (3.84) and CD14 (3.25). Conclusions: Pts receiving TLPLDC vaccine had significantly improved OS and DFS, while outcomes remained similar between those who received TLPLDC+G vs placebo. Pts who did not receive G-CSF had higher expression of genes linked to DC maturation and antigen processing and presentation, likely explaining the improvement in clinical efficacy. A phase III trial to further assess the TLPLDC vaccine to prevent recurrence is planned. Clinical trial information: NCT02301611.

Interim results of viagenpumatucel-L (HS-110) plus nivolumab in previously treated patients (pts) with advanced non-small cell lung cancer (NSCLC) in two treatment settings

9100

Background: Viagenpumatucel-L (HS-110) is an allogeneic cell therapy derived from a human lung adenocarcinoma cell line incorporating multiple cancer testis antigens and transfected with a gp96-Ig fusion protein. Methods: We report interim results of cohort A (previously treated pts who had not received a checkpoint inhibitor [CPI]) and cohort B (pts who progressed after CPI treatment) in an ongoing phase 2 trial evaluating HS-110 plus nivolumab (NIVO) in advanced NSCLC pts (NCT02439450). Pts received HS-110 (1×107 cells) intradermally QW for 18 wk and NIVO Q2W until tumor progression. Stratified analyses were performed by injection site reaction (ISR), yes (+) or no (–); baseline blood tumor mutational burden (bTMB), bTMB-L (<10 mutations/ megabase [mut/Mb]) or bTMB-H (≥10 mut/Mb) by FoundationACT test; and baseline PD-L1 expression, – (<1%) or + (≥1%). Results: As shown in the Table, median progression-free survival (PFS) in cohort A (n=47) was 1.8 mo (95% CI 1.8-7.8) and median overall survival (OS) was 24.6 mo (95% CI 11.7-36.0) after a median follow-up (MFU) of 19.5 mo. We observed significantly longer PFS and OS in ISR+ pts (hazard ratio [HR] 0.43, p=0.01; HR 0.23, p<0.001) and longer OS in PD-L1+ pts (HR 0.25, p=0.02). In cohort B (n=68), median PFS was 2.8 mo (1.8-3.9) and median OS was 11.9 mo (9.7-16.3) after a MFU of 11.9 mo. We observed significantly longer OS in ISR+ pts (HR 0.48, p=0.03) and a trend toward extended OS in bTMB-L pts (HR 0.58, p=0.20). HS-110 TEAEs were reported in 21 (44.7%) pts in cohort A and 18 (26.5%) pts in cohort B. TEAEs in >5% of pts included fatigue, maculopapular rash, nausea, diarrhea, and pruritus. Few HS-110–related TEAEs led to discontinuation of treatment [cohort A, 5 (10.6%); cohort B, 3 (4.4%)], and no serious AEs were considered related to HS-110. Conclusions: HS-110 was well tolerated when administered in combination with NIVO. In previously treated pts with advanced NSCLC, we observed (1) significantly longer PFS and OS in ISR+ pts in both CPI naïve and CPI progressor cohorts; (2) significantly longer OS in PD-L1+ patients in the CPI naïve cohort; and (3) a trend of improved OS in bTMB-L pts in the CPI progressor cohort. Further clinical evaluation of HS-110 is warranted in both CPI naïve and CPI progressor NSCLC patients. Clinical trial information: NCT02439450. [Table: see text]

Breast cancer grade and clinical benefit in patients with advanced breast cancer treated with an engineered whole tumor cell-targeted immunotherapy alone or in combination with checkpoint inhibition

3033

Background: SV-BR-1 is a breast cancer cell line derived from a grade II (moderately differentiated) tumor. SV-BR-1 was transfected with the CSF2 gene (encoding GM-CSF) to form SV-BR-1-GM. SV-BR-1-GM expresses HLA class I & II antigens and has functional antigen-presenting cell activity, directly stimulating CD4+ T cells in an HLA-DR restricted fashion. The SV-BR-1-GM regimen consists of low-dose cyclophosphamide (300 mg/m2) to reduce immune suppression, intradermal inoculation with irradiated SV-BR-1-GM (20x106 cells divided into 4 sites) and interferon-α2b (10,000 IU into each inoculation site ~2 & 4 days later) to boost the response. Here, we evaluate the impact of tumor grade on clinical benefit following treatment with the SV-BR-1-GM regimen. Methods: Patients with advanced breast cancer were treated with either the SV-BR-1-GM regimen alone or with the SV-BR-1-GM regimen with pembrolizumab. For the SV-BR-1-GM regimen alone, cycles were administered every 2 weeks x 3 and then monthly, while combination with pembrolizumab (200 mg IV 1-5 days following SV-BR-1-GM inoculation) administered cycles every 3 weeks. Tumor restaging was every 6-12 weeks. Results: 33 patients were enrolled. The treatment was generally safe with inoculation site pruritis, erythema and induration the most common adverse events. 23 patients had grade III (poorly differentiated) tumors, 9 had grade II tumors and one had a grade I (well differentiated) tumor. None of the patients with grade III tumors exhibited clinical benefit. 7 patients with grade I/II tumors received the SV-BR-1-GM regimen alone, 2 received the SV-BR-1-GM regimen with pembrolizumab and 1 received both regimens. As noted in the Table, 7 patients experienced clinical benefit including all 3 patients treated in combination with pembrolizumab. This included 6 patients with stable disease and one with a partial response. Conclusions: The SV-BR-1-GM regimen with or without pembrolizumab appears safe and able to induce clinical benefit even in very heavily pre-treated patients with low or intermediate grade advanced breast cancer. Clinical trial information: NCT03328026 . [Table: see text]

ESR1 mutations provide novel targets for breast cancer immunotherapy

3135

Background: Estrogen receptor (ER)-positive breast cancer is not considered immunogenic. Standard treatment is endocrine therapy to include aromatase inhibitors (AI). However, constitutively activating mutations in estrogen receptor alpha ( ESR1) emerge with treatment making tumors resistant to AI therapy. While these mutations represent a pathway of resistance, they also represent potential neoepitopes that can be targeted with immunotherapy. Here we characterize the role of ESR1 mutations as novel targets for breast cancer immunotherapy. Methods: Immunogenic epitopes derived from mutated ESR1 (i.e. D538G, Y537S and E380Q) were identified in silico using the Immune Epitope Database and by determining overlapping peptides. In vitro T2 binding assays were used to measure the affinities of these peptides to HLA class-I, specifically HLA-A*0201. Dissociation assays were employed to characterize the stability of the peptide-HLA complex. Peptide-HLA-A*0201 tetramer staining was used to determine the expansion potential of peptide-specific cytotoxic T lymphocytes (CTL) from peripheral blood of healthy females. Cytotoxicity assays were used to determine the ability of peptide-specific CTLs to lyse cells presenting mutated ESR1-derived peptides. Results: We identified 22 nonameric and decameric peptides derived from the most common ESR1 mutations; 10/22 demonstrated high affinity (i.e. IC50 < 500nM) binding to HLA-A*0201. The 3 highest predicted peptides demonstrated low IC50 values (13 nM, 19.5 nM and 56.6 nM), indicating very tight binding to HLA-*0201. In vitro assays confirmed high affinity binding for 10 of the 22 in silico-predicted peptides with an average fold change of 1.52 compared to non-pulsed T2 cells, and a median dissociation half-life of 6.45 hours. Tetramer staining of peptide specific CTLs from normal donor peripheral blood mononuclear cells showed relatively high expansion frequencies, with the highest three frequencies noted for D538G (1.04%), Y537S (0.49%) and V392I (0.27%). Using 4-hour in vitro cytotoxicity assays, in comparison with non-pulsed T2 cells, there was significantly higher lysis of peptide pulsed T2 cells that were cocultured with matching peptide-specific CTL: D538G (67.1 % vs 36.9%, P < 0.001), Y537S (59.5% vs 37.5%, P < 0.01), and E380Q (36.3% vs 7.8%, P < 0.001). Conclusions: These data confirm the immunogenicity of epitopes derived from the most common ESR1 mutations. Further investigation of these peptides as part of novel immunotherapies, to include vaccine strategies is warranted.

Multi-institutional, prospective, randomized, double-blind, placebo-controlled phase IIb trial of the tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine to prevent recurrence in high-risk melanoma patients: A subgroup analysis

63

Background: A novel vaccine strategy may prevent recurrence in high-risk melanoma patients (pts). The TLPLDC vaccine uses yeast cell wall particles (YCWP) to load tumor lysate into autologous dendritic cells (DC). In this phase IIb trial of TLPLDC vs. placebo in resected stage III/IV pts, TLPLDC increased 24 month (mo) disease free survival (DFS) in the per treatment (PT) population. Here, we present a 24mo DFS subgroup analysis and estimated overall 36mo DFS. Methods: Disease-free pts were randomized 2:1 to the TLPLDC vaccine vs. unloaded YCWP+DC at 0, 1, 2, 6, 12, and 18mo. The protocol was amended to allow concurrent adjuvant checkpoint inhibitor (CPI) therapy once approved. The pre-specified PT population included only pts completing the primary vaccine/placebo series (PVS) at 6 mo. Kaplan-Meier estimates of DFS were used to compare treatment arms by stage (III or IV) and CPI therapy (yes/no) in the ITT and PT populations. Results: 144 pts were randomized (103 TLPLDC, 41 placebo); 98 pts (66 TLPLDC, 32 placebo) completed the PVS. There were no clinicopathologic differences between treatment groups. There was no difference in 24mo DFS in stage III pts (n = 112), but in stage IV pts (n = 32), the 24mo DFS was 44% vs 0% (TLPLDC vs placebo) (p = 0.41) in ITT and 73.3% vs. 0% (HR 0.14, p = 0.002) in PT. Stage IV pts were more likely to receive CPI than stage III pts (50% vs. 30%, p = 0.003). There was no difference in 24mo DFS for pts who did not receive CPI (n = 102), but in pts who received CPI (n = 42), the 24mo DFS was 49.3% vs. 31.3% (p = 0.71) in ITT and 68.8% vs. 41.7% (HR 0.46, p = 0.28) in PT, showing a trend toward improved DFS in pts who completed the PVS and received CPI (n = 31). Overall, the 36mo estimated DFS was 34.2% vs. 21.6% (p = 0.89) for ITT and 56.9% vs. 27.9% (p = 0.021) for PT. Conclusions: The TLPLDC vaccine improved DFS in patients completing the PVS at 24 and 36 mos, particularly in the resected stage IV subset. The apparent synergistic effect with TLPLDC + CPI will be confirmed in a phase III study evaluating adjuvant TLPLDC + CPI vs. CPI alone in resected stage IV melanoma pts. Clinical trial information: NCT02301611.

Results of a phase Ib trial of encapsulated rapamycin in prostate cancer patients under active surveillance to prevent progression

34

Background: At low doses, rapamycin inhibits cell proliferation and angiogenesis while augmenting CD8 T-cell responses, cumulatively producing an antitumor effect. Oral rapamycin is limited by variable bioavailability. Encapsulated rapamycin (eRapa) incorporates submicron rapamycin particles into a pH-sensitive polymer, improving bioavailability and allowing for consistent and lower dosing. Here, we present results of a phase Ib trial evaluating safety and treatment effects of eRapa in patients with low-grade prostate cancer (PCa). Methods: PCa patients with Gleason ≤7 (3+4) under active surveillance were enrolled in a 3+3 study with 3 dosing cohorts (0.5mg weekly, 1mg weekly, and 0.5mg daily) to determine the optimal dosing. Patients were treated for 3 months (m) and followed for 6m. Safety, labs (including PSA), pharmacokinetics, immune response, and quality of life (QOL) were assessed for each cohort. Results: 14 patients were enrolled; 3 in cohort 1, 3 in cohort 2, and 8 in cohort 3. 2 patients withdrew for non-dose limiting toxicity (DLT) (grade 1-2) adverse events (AEs) in cohort 3, leaving 6 evaluable. A single grade 3 DLT (neutropenia) occurred in cohort 3. No AEs > Grade 1 occurred in cohorts 1/2. Peak serum rapamycin concentration ([Rapa]) was 7 ng/mL after a 1 mg dose (2h after administration). Stable trough levels (2 ng/mL) were established after 48 hrs and persisted to 13wks. Central memory CD8 T cells and CD3+/CD56+ NK cells were more prevalent in cohort 3 than other cohorts at 1m (p = 0.027 and p = 0.041) and 3m (p = 0.023 and p = 0.049). There was no significant change in PSA level; no patients clinically progressed on therapy. In cohort 3, there were no differences between baseline and 3m QOL assessments but there was a suggestion of withdrawal effects at 6m. Conclusions: Treatment with low dose eRapa is safe and well-tolerated. The dose of 0.5mg daily produced stable serum [Rapa] through the duration of treatment and resulted in a positive immune impact. Further investigation with low dose and/or intermittent dosing of eRapa as a preventive agent in PCa and other indications will be required to establish clinical benefit. Clinical trial information: NCT03618355.

Docosahexaenoic acid varies in rat skeletal muscle membranes according to fibre type and provision of dietary fish oil

BACKGROUND

Dietary fish oil provides polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) and is associated with modified oxygen consumption, contractile fatigue and physiological responses to ischaemia or hypoxia in striated muscle. This study systematically investigated the membrane incorporation of fatty acids, with a focus on DHA, into skeletal muscle in relation to functional/metabolic differences and their responsiveness to fish oil doses.

METHODS

Male Sprague-Dawley rats were randomised to isoenergetic diets (10% fat by weight). Human Western-style diets were simulated with 5.5% tallow, 2.5% n-6 PUFA sunflower seed oil and 2% olive oil (Control). High-DHA tuna oil exchanged for olive oil provided a Low (0.32%) or moderate (Mod) (1.25%) fish oil diet. Membrane phospholipid fatty acid composition was analysed in samples of five skeletal muscles selected for maximum variation in muscle fibre-type.

RESULTS

Concentrations of DHA varied according to muscle fibre type, very strongly associated with fast oxidative glycolytic fibre population (r² = 0.93; P < 0.01). No relationship was evident between DHA and fast glycolytic or slow oxidative fibre populations. Fish oil diets increased membrane incorporation of DHA in all muscles, mainly at the expense of n-6 PUFA linoleic and arachidonic acid.

CONCLUSION

The exquisite responsiveness of all skeletal muscles to as little fish oil as the equivalent of 1-2 fish meals per week in a human diet and the selective relationship to fatigable muscle fibre-types supports an integral role for DHA in muscle physiology, and particularly in fatigue resistance of fast-twitch muscles.

SUMMARY

Skeletal muscle fibres vary according to structural, metabolic and neurological characteristics and ultimately influences contractile function. This study sort to determine if the composition of phospholipid polyunsaturated fatty acids (PUFA), incorporated in their membranes, might also differ according to fibre type and when omega-3 PUFA are made available in the diet. We systematically demonstrated that the omega-3 PUFA, docosahexaenoic acid (DHA), incorporated into skeletal muscle membranes well above its provision in the diet and without competitive influence of high omega-6 PUFA concentrations, typical to the Western-style human diet. Notably, incorporation preferentially occurred according to metabolic characteristics of each muscle, supporting the notion that DHA plays an integral role in fast oxidative glycolytic muscle fibres.

Immunologic responses in triple-negative breast cancer patients in a randomized phase IIb trial of nelipepimut-S plus trastuzumab versus trastuzumab alone to prevent recurrence

556

Background: Breast cancer (BC) patients (pts) expressing low levels of HER2 by (immunohistochemistry (IHC) 1-2+) are not eligible for trastuzumab (Tz). However, in a randomized phase 2b trial, triple negative BC (TNBC) pts demonstrated a significantly better DFS with nelipepimut-S (NPS) + Tz vs Tz alone. Here, we assess the ex vivo and in vivo immune responses (IR) in both arms. Methods: Disease-free pts (n = 275) with HER2 IHC 1-2+, non-amplified BC who were node positive and/or had TNBC were randomized 1:1 to granulocyte-macrophage-colony stimulating factor (GM-CSF) or NPS+GM-CSF. ±NPS was given every 3 weeks x 6 followed by 4 boosters every 6 months (mo). All pts received Tz concurrently for 1 year per label regimen and were followed for recurrence. IR were evaluated ex vivo by clonal expansion of NPS-specific cytotoxic T lymphocytes (CTL) by dextramer-staining/flow cytometry at time points over 3 years. In vivo IR were assessed by delayed type hypersensitivity (DTH) reactions periodically. Results: The trial enrolled 97 TNBC pts; 60 had 4 timepoints available for analysis (37 NPS + Tz pts; 23 Tz pts). The NPS+Tz group exhibited increases in CTL frequencies vs baseline: 208%, 303%, 379% at 18, 24 and 30 mo, respectively. NPS+Tz pts’ mean CTL frequencies increased from 0.029 ±0.001% at baseline to 0.112±0.026% at 30 mo (p = 0.01) compared to Tz pts who were 0.027 ±0.001% at baseline and 0.057 ±0.016% at 30 mo (p = 0.71). Only 4 NPS+Tz pts recurred as compared to 13 in the Tz arm. While limited by low numbers, recurrent NPS + Tz pt did not mount an IR by ex vivo assessment (range: 0.0 - 0.026%) or by DTH (all measurements: 0 mm), while non-recurrent pts mounted both clonal CTL expansion (range: 0.000- 0.33%) and enhanced DTH (range: 0.0- 80.5mm). Conclusions: NPS+Tz combination is more efficacious in generating time-dependent antigen (NPS)-specific CTL by both ex vivo and in vivo measures vs Tz. Based on these preliminary data, it appears that both ex vivo and in vivo IR to NPS were attenuated in pts with TNBC recurrence. Further analysis of read-outs from these assays to validate the relationship of IRs to clinical effect seen with NPS+Tz in TNBC pts is underway. Clinical trial information: NCT02297698.

Clinical efficacy of vaccination with the autologous tumor lysate particle loaded dendritic cell (TLPLDC) vaccine in metastatic melanoma

e21025

Background: The treatment of melanoma has changed drastically with the advent of immunotherapy. The autologous tumor lysate, particle loaded, dendritic cell (TLPLDC) vaccine stimulates T-cells and may work synergistically with other immunotherapies. Here, we describe results in patients (pts) with metastatic melanoma (MM) treated with the TLPLDC vaccine together with other approved therapies. Methods: The TLPLDC vaccine is created using autologous tumor lysate loaded yeast cell wall particles to prime autologous dendritic cells ex-vivo. 1-1.5x106 TLPLDCs are given via intradermal injection monthly x 4 followed by boosters at six and nine months (mo). Pts who recurred while enrolled in our adjuvant phase IIb trial of the TLPLDC vaccine and pts with MM with measurable disease enrolled in a separate phase I/IIa trial were offered vaccination of TLPLDC vaccine in an open-label fashion in addition to other approved therapies as determined by their treating physician. Tumor response is measured by RECIST 1.1 criteria. Results: To date, 50 pts have been enrolled in the two trials (25 pts in each). Of the 42 pts with measureable disease, 30 pts received at least one dose of the vaccine, 11 progressed prior to vaccine administration, and 1 is pending. 2 pts withdrew at 2 and 7 mo. Of the remaining 28 evaluable pts, 13 pts had progressive disease with a median follow-up (f/u) of 3 (range 0-12) mo, 12 pts had stable disease with a median f/u of 7.5 (range 1-23) mo, 2 pts had a partial response with f/u of 7 and 13 mo, and one pt had a complete response with 18 mo of f/u. Overall, in pts with measureable disease, the disease control rate was 54% (15/28) and objective response rate was 11% (3/28). 8 pts were without measurable disease at enrollment, 3 recurred at a median f/u of 8 mo and 5 remain disease-free at a median of 26 mo f/u. No grade ≥ 3 toxicities were observed with combination TLPLDC vaccination and approved systemic therapies. Conclusions: Vaccination with the TLPLDC vaccine in combination with systemic approved therapies in MM pts is well tolerated and may provide clinical benefit in patients with and without measurable disease. Clinical trial information: NCT02678741.

Final analysis of nelipepimut-S plus GM-CSF with trastuzumab versus trastuzumab alone to prevent recurrences in high-risk, HER2 low-expressing breast cancer: A prospective, randomized, blinded, multicenter phase IIb trial

1

Background: Preclinical data shows synergism between trastuzumab (Tz) and HER2-targeted vaccines. We evaluated adjvuant nelipepimut-S (NPS) + GM-CSF with Tz compared to Tz with GM-CSF alone in HER2 low-expressing (LE) breast cancer (BC) patients (pts) to prevent recurrences. After a planned interim analysis showed benefit in triple negative BC (TNBC) pts, the decision was made to close the trial with guidance from the independent DSMB. Here, we report the final analysis of the trial with 7 months (mo) of added follow-up (f/u). Methods: The phase 2b trial enrolled clinically disease-free BC pts after standard therapy. Pts were HLA-A2, A3, A24, and/or A26+, had HER2-LE (IHC 1-2+, FISH non-amplified) BC and were node positive and/or TNBC. Pts were randomized to placebo with GM-CSF(control group, CG) or NPS with GM-CSF (vaccine group, VG), while all received Tz Q3wk for 1 year. GM-CSF or NPS + GM-CSF were given q3wks x 6 starting with the 3rd Tz dose, and boosters every 6 months x 4. Safety was assessed and pts were followed clinically for recurrences. The primary outcome was DFS at 24 mo. Results: 589 pts were screened at 26 sites. 275 pts were enrolled and randomized (VG:136, CG:139). There were no clinicopathologic differences between groups. Concurrent Tz and NPS was safe with no added overall or cardiac toxicity compared to CG and no grade 4/5 toxicities. In the ITT analysis (median f/u 25.7 mo), the estimated DFS was favorable but did not reach significance in the VG compared with the CG (HR 0.62, 95% CI: 0.31-1.25, p = 0.18). In the TNBC pts, the VG had statistically improved DFS compared to the CG (HR 0.26, 95% CI: 0.08-0.81, p = 0.013). Conclusions: The combination of NPS with Tz is safe with no added toxicity compared to Tz alone, even after prolonged exposure (25.7 mo). In this final analysis, there was a trend towards benefit in the ITT population that improved since the interim analysis with added f/u. The significant benefit seen at interim in the TNBC pts continued to strengthen in the VG group. These findings could position the NPS + Tz combination as an adjuvant therapy for early-stage TNBC and warrant further study. Clinical trial information: NCT01570036.

Association of intratumoral FoxP3 T-regulatory lymphocytes and perineural invasion in colorectal adenocarcinoma

51

Background: In colorectal cancer, higher densities of lymphocytes in the tumor microenvironment (TME) have been associated with better clinical outcomes. FoxP3+ regulatory T-cells (Tregs) are a subset of lymphocytes that play an immunosuppressive role in the TME. However, the impact of Tregs in the TME in colon cancer prognosis is more controversial. We evaluated the densities of FoxP3+ Tregs at multiple locations in matched endoscopic biopsies and resection specimens from patients with colonic adenocarcinoma to assess concordance of Treg densities between locations, and the association with prognostic factors. Methods: Patients with banked, matched endoscopic biopsies and surgically resected colon adenocarcinoma specimens from a single institution from 2006-2016 were selected for evaluation. Paraffin embedded tissue samples were cut and stained with FoxP3 immunohistochemical stain. The densities of FoxP3 positive cells were counted within a 1 mm2 area at the center of the tumor and at the invasive margin. The densities of FoxP3 positive lymphocytes were compared between the center and invasive margin, and to prognostic factors. Results: 107 matched endoscopic biopsies and surgical resection specimens were evaluated. A moderate-strong correlation was noted in levels of FoxP3+ cells between endoscopic biopsies and resected specimens at the center of the tumor (r= 0.68) and invasive margin (r=0.69). Higher FoxP3 densities were associated with a decreased rate of perineural invasion (P= 0.040). Levels of Tregs in endoscopic biopsies were correlated with the levels in the larger tumor of resected colon adenocarcinoma specimens. There was a weak correlation between increased density of Tregs and lower anatomic stage (R2 = 0.05). Conclusions: Tregs are a potential biomarker that can be evaluated in neoadjuvant immunomodulatory therapies in clinical trials to assess for response. Moreover, Treg levels are associated with perineural invasion, a predictive factor for decreased response to chemotherapy, underscoring the potential for immunomodulatory therapies in colorectal adenocarcinoma.

Paradoxical effect of regulatory T-cell density in the invasive margin on colon cancer disease-free survival

47

Background: Increased numbers of FoxP3+ regulatory T cells (Treg), an immunosuppressive T cell subpopulation, in the tumor microenvironment (TME) has been associated with decreased recurrence risk in colon cancer. We assessed the association of Treg levels and disease-free survival (DFS) to confirm correlation with recurrence risk and to evaluate the impact on DFS in patients with colon cancer. Methods: Cases of colonic adenocarcinoma with endoscopic biopsies who had curative resection were collected from 2006-2016. The tissue sections were stained with FoxP3 immunohistochemical stain. FoxP3+ cells (Tregs) were counted with a digital imager software program and reported as cells per square mm. DFS from time of surgery was determined with a retrospective chart review. FoxP3 levels were compared with a Man-Whitney U test and DFS was compared with a Spearman’s test and regression. Results: 109 matched endoscopic biopsy colonic adenocarcinoma specimens were gathered. 94 cases had at least 4 months of follow up and were analyzed. The recurrence rate was 21.3% (20/94) with a median recurrence time of 13.5 months. The median time to follow up in patients with no recurrence was 39 (range 4-116) months. Tregs in those that recurred had a mean density of 152 (range 9-1267) at the invasive margin compared to 251 (range 15-485) in the cases that did not yet recur (p = 0.005). The same association was observed with Treg density in the center of the tumor (p = 0.03). In the cases that had a recurrence, there was a moderate, inverse correlation between Tregs at the invasive margin and time to recurrence (Spearman’s correlation coefficient = -0.46, p = 0.04.) A logarithmic inverse relationship between Tregs at the invasive margin and time to recurrence was observed (Correlation coefficient -0.63, p = 0.003). Conclusions: Treg density in endoscopic biopsies in colon adenocarcinoma is associated with recurrence risk, consistent with previously reported observations. Paradoxically, in patients who did recur, higher Treg density was associated with shorter time to recurrence. This discordant relationship of Treg density and colon cancer prognosis warrants further investigation.

Abstract P2-09-09: Initial safety and efficacy of a phase I/IIa trial of a modified whole tumor cell targeted immunotherapy in patients with advanced breast cancer

Background: SV-BR-1-GM is a GM-CSF transfected breast cancer cell line which expresses HLA class I & II antigens. In a previous clinical trial, a partial response of widely metastatic breast cancer was seen in a patient who matched SV-BR-1-GM at HLA-DRB3*02:02. Here we report the safety and efficacy analysis with immunologic correlates of response in the initial patients in a phase I/IIa trial of SV-BR-1-GM in patients with advanced breast cancer

Methods: This phase I/IIa trial enrolled patients with recurrent and/or metastatic breast cancer refractory to standard chemotherapy/targeted-therapy. Patients received low-dose cyclophosphamide 2-3d prior to intradermal injection of SV-BR-1-GM (20x106 cells divided into 4 sites) and interferon-α into the inoculation sites (10,000 IU/site) ˜2 & 4 days subsequently. Cycles were 2 weeks x3 then q mo x 3. Adverse events (AE) were evaluated after each inoculation and graded via CTCAE v4.03. Immunologic response was measured by delayed type hypersensitivity (DTH) after each inoculation. Disease response was evaluated radiographically q3 mo and as clinically indicated (clinical trial NCT03066947).

Results: To date, twenty-two patients have been enrolled and 17 have been inoculated for a total of 39 SV-BR-1-GM inoculations given. Per inoculation, the maximum related AE was grade 1 in 64%, grade 2 in 7.7%, and grade 3 in 7.7%. There were no related grade &gt;3 or unexpected AE. Efficacy data is available on the first six (Table). Tumor regression was seen in 2 patients. 01-002 presented with liver, bone and 20 classic miliary lung metastases (up to 9mm). This subject previously received 7 chemotherapy regimens. She matched SV-BR-1-GM at Class I & II HLA loci. Imaging at 3 mo showed virtually complete regression of all 20 identifiable lesions in the lungs. This response was maintained at 6 mo but the subject was taken off protocol because of disease progression (liver and bone). 01-005, matching HLA-A*24:02, had notable regression of cutaneous lesions, but progressed in pleural and pericardial effusions, had irreversible cardiac arrest (unlikely related). DTH increased in 01-002 from 4mm (first dose) to 47mm (8th dose). Three of 3 patients evaluated developed antibodies responses (as measured by flow cytometry with SV-BR-1) including 01-002. Interleukin 8 also increased in 01-002.

Conclusions: SV-BR-1-GM in this regimen appears to be safe and well-tolerated. In this initial exploratory analysis, SV-BR-1-GM can produce regression of pre-treated metastatic breast cancer correlating with an immunologic response. HLA matching is being evaluated as a predictor of response.

PatientAgeMetastatic Sites# Prior RegimensHLA Matches# of CyclesTumor Regression?01-00146Pleura, Lymph Nodes7 chemo/bio, 5 hormonalDRB3*02:021No01-00273Lung, Liver, Bone6 chemo, 1 hormonalA*24:02, DRB3*02:028Lungs01-00554Lymph nodes, Pleura, Skin3 chemo/bioA*24:022Skin02-00170Lymph nodes1 chemo/bioNone1No02-00361Bone, Brain3 chemoNone6No02-00474Lymph nodes, Cutaneous3 chemo/bio, 1 hormonalDRB3*02:022Lost to Follow-up

Citation Format: Bhattacharya S, Holmes JP, Calfa C, Lukas J, Tan-Chiu E, Clifton GT, Peoples GE, Lacher M, Wiseman CL, Williams WV. Initial safety and efficacy of a phase I/IIa trial of a modified whole tumor cell targeted immunotherapy in patients with advanced breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-09.

Abstract P2-09-01: Subgroups analysis of a multicenter, prospective, randomized, blinded phase 2b trial of trastuzumab + nelipeptimut-S (NeuVax) vs trastuzumab for prevention of recurrence in breast cancer patients

Background:HER2 low-expressing (LE) (IHC 1-2+, FISH non-amplified) breast cancer (BC) patients (pts) have not benefited from HER2-directed therapy despite HER2 antigen availability. Triple negative BC (TNBC), in particular, is immunogenic and in need of additional therapeutic options. We have previously shown the HER2-derived nelipeptimut-S (E75) + GM-CSF (NeuVax) to be synergistic with trastuzumab (Tz) in pre-clinical and pilot clinical studies. In a planned interim analysis of a multi-center, prospective, randomized, single-blinded, placebo-controlled phase 2b trial of Tz + NeuVax vs Tz to reduce recurrence in HER2 LE, node-positive (NP) and/or triple negative BC (TNBC) pts, we previously reported that the NeuVax + Tz was safe without added cardiac toxicity and demonstrated a significant reduction of recurrences in TNBC pts. This analysis examines additional subsets in this trial.

Methods:HER2 LE, NP and/or TNBC pts who were clinically disease-free after standard therapy were randomized to receive Tz+NeuVax (vaccine group; VG) or Tz+GM-CSF (control group; CG). All pts received 1 yr of Tz per label. NeuVax or GM-CSF was given every 3 weeks x 6 starting with the 3rdTz dose, and then boosted every 6 months x 4. This pre-specified interim analysis was triggered 6 months after last enrollment. The primary endpoint is intention-to-treat 24 month disease-free survival (DFS) evaluated by log rank.

Results: Of 275 pts randomized in the study (VG n=136, CG n=139), 98 had TNBC (VG=53, CG=45). In the interim analysis, estimated disease-free survival (DFS) was assessed with a median follow up of 18.8 months. No significant clinicopathologic differences were seen between treatment groups. In the TNBC group, estimated DFS was higher overall in VG vs CG (91.9% v 69.9%, p=0.023; hazard ratio [HR] 0.29, 95% confidence interval [CI] 0.09-0.90). On TNBC subgroup analysis, estimated DFS was higher in VG vs CG among pts who received neoadjuvant chemotherapy (VG n=35, CG n=31; HR 0.26, CI 0.07-0.93; p=0.03), HER2 IHC 1+ BC (VG n=34, CG n=28; HR 0.20, CI 0.04-0.96; p=0.03), pts who were AJCC 7thedition stage I/II (VG n=37, CG n=27; HR incalculable, no recurrences in the VG, p=0.008), and pts 351yr of age (VG n=32 & CG n = 26; HR 0.26 CI 0.07,0.94; p=0.009). HRs did not appreciably vary based on the histologic grade or presence of lymphovascular invasion.

Conclusion:Examining the subgroups from the pre-specified interim analysis demonstrates a highly significant clinical benefit in TNBC pts overall. Within the TNBC cohort, specific benefit was seen in pts who received chemotherapy neoadjuvantly, expressed lower HER2, were earlier stage, and were older in age. These factors may help enrich the TNBC population targeted in a definitive Phase 3 study in TNBC patients with residual disease after neoadjuvant chemotherapy.

Citation Format: Clifton GT, Kemp Bohan PM, Hale DF, Myers JW, Brown TA, Holmes JP, Vreeland TJ, Litton JK, Murthy RK, Mittendorf EA, Peoples GE. Subgroups analysis of a multicenter, prospective, randomized, blinded phase 2b trial of trastuzumab + nelipeptimut-S (NeuVax) vs trastuzumab for prevention of recurrence in breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-01.

A prospective, randomized, blinded, placebo-controlled, phase IIb trial of an autologous tumor lysate + yeast cell wall particles (YCWP) + dendritic cells (DC) vaccine vs unloaded YCWP + DC and embedded phase I/IIa trial with tumor lysate particle only (TLPO) vaccine in stage III and stage IV (resected) melanoma to prevent recurrence

TPS201

Background: Melanoma is a potentially lethal skin malignancy; patients with stage III/IV resected disease have a recurrence rate of 50-90%. Adjuvant checkpoint inhibitor immunotherapy decreases the risk of recurrence but also causes significant immune-related toxicity. Vaccines are a promising strategy for patients with high risk melanoma. The optimal time to intervene may be in the adjuvant setting after attaining a disease-free state through standard of care therapies. Our strategy uses autologous tumor lysate (TL) in a yeast cell wall particle (YCWP) to load dendritic cells (DC) ex vivo. The tumor lysate particle loaded dendritic cell (TLPLDC) vaccine is then given to prevent melanoma recurrences. An alternate vaccine delivery method that we are evaluating utilizes the tumor lysate particle-only (TLPO) technique, in which tumor lysate is loaded into capped YCWP and injected intradermally, allowing an in vivo uptake by the patient’s dendritic cells. Methods: We are performing a prospective, randomized, blinded, placebo-controlled phase IIb trial in patients with resected stage III/IV melanoma who have been rendered disease-free but remain at high risk of recurrence. The study will utilize the TLPLDC strategy vs placebo (2:1) in 120 patients, followed by a bridging study of TLPO vs TLPLDC (2:1) in 60 patients. Both TLPLDC and TLPO inoculations will be monthly x3, followed by boosters at 6, 12, and 18 months. Primary endpoints will be disease free survival (DFS) at 24 months in the TLPLDC arm, and overall safety in the TLPO arm. We have completed enrollment in the phase IIb portion of the study. Clinical trial information: NCT02301611.

Immunologic efficacy of E39 & E39' vaccination in a phase I/IIa trial in ovarian and endometrial cancer patients

75

Background: The treatment options for cancer are ever-evolving & now include vaccines targeting tumor-specific immunogenic peptides to induce tumor cytolysis. Folate binding protein (FBP) is a tumor-associated antigen (TAA) highly expressed in most endometrial & ovarian cancers (Ca), shielded from the normal immune system. The most promising FBP peptides are E39 & an attenuated form, E39' (aka J65). In our most recent phase I/IIa trial we evaluated an E39+GM-CSF inoculation series at 3 doses (VG) vs controls (CG) as well as booster vaccination with E39 or E39' after the initial inoculation series. Here we present the immunologic data from this phase I/IIa trial. Methods: Patients (pts) with ovarian or endometrial Ca who were disease-free after standard of care therapy but at risk for recurrence were enrolled. HLA-A2+ pts were vaccinated in a 3+3 dose escalation of 100mcg, 500mcg, & 1000mcg. The remaining pts received 1000mcg inoculations. Vaccine was given every 3-4 weeks for a total of 6 inoculums. Pts were then offered to participate in booster vaccination with 9 pts randomized to receive E39 & 9 pts E39'. FBP expression level was measured on the resected disease. Overall immunologic response & by subgroups was measured by delayed type hypersensitivity (DTH) & ELISPOT in the VG. Results: A total of 29 pts were vaccinated. Mean DTH prior to the initial dose of E39 was 5.74mm & after final dose was 10.33mm (p = 0.018). Mean overall ELISPOT change over time through 18 months was +69.1 when compared to baseline (p = 0.675). At 18 months, mean ELISPOT increased by 97.1 in 1000mcg vs -57.0 in < 1000mcg dosed pts (p = 0.047) & by +255.33 in pts with > average initial DTH vs -0.75 in < average initial DTH (p = 0.004) when compared to baseline. Immunological analyses were not significantly different between FBP hi/lo expression or E39 vs E39’ booster (p > 0.05). Conclusions: E39 demonstrated significant overall immunogenicity on in vivo testing as measured by DTH. Ex vivo analysis (ELISPOT) suggests that E39 is more immunogenically efficacious in pts with > average initial DTH & those who are optimally dosed (1000mcg). FBP expression level & E39 vs E39’ use in booster inoculations did not significantly impact in vivo or ex vivo immunogenicity. Clinical trial information: NCT01580696.

Subgroup efficacy evaluation of the AE37 HER2 vaccine in breast cancer patients in the adjuvant setting

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Background: AE37 is a Ii-Key hybrid of the HER2 peptide AE36 (HER2776-790), which stimulates peptide-specific T cells. We have completed the active phase of a prospective, randomized, multi-center, phase II trial of the AE37 vaccine in the adjuvant setting. The primary analysis, performed after a median follow up (f/u) of 25 months (mo), did not show a significant difference in disease free survival (DFS) between vaccinated and control patients (pts). However, demonstrating the efficacy of cancer vaccines may require more time than other therapies, especially in malignancies with relatively late recurrences like breast cancer. Here, we present updated efficacy data after extended f/u in subgroups of pts stratified by clinicopathologic characteristics. Methods: Clinically disease-free, node positive or high-risk node negative pts with any level of HER2 expression were randomized to receive AE37 + GM-CSF (VG) or GM-CSF alone (CG) following standard of care therapy. Pts received 6 monthly intradermal inoculations during the primary vaccine series (PVS) followed by 4 boosters administered every 6 mo. Kaplan Meier and log rank analyses were performed from the time of the first inoculation in pts who completed at least the PVS, according to stage, node status, tumor size, HER2 expression and ER/PR status. Results: There were no clinicopathologic differences between groups in the 298 enrolled pts (VG = 153, CG = 145). The vaccine is safe and well tolerated. After a median f/u of 55 mo, there was a trend toward improved DFS in the VG among stage IIB/III pts (VG, n = 73, DFS 82% vs CG, n = 61, 67%, HR = 0.48, p = 0.06) and those with low HER2 expression (HER2 LE, VG, n = 68, 89% vs CG, n = 66, 51%, HR = 0.47, p = 0.1). Improved DFS in the VG was documented in patients with both stage IIB/III disease and HER2 LE (VG, n = 39, 90% vs CG, n = 38, 32%, HR 0.3, p = 0.02) and triple negative (TNBC) pts (VG, n = 21, 89% vs CG, n = 21, 0%, HR 0.26, p = 0.05). Conclusions: The AE37 vaccine is safe and well tolerated and has statistically significant efficacy in stage IIB/III pts with HER2 LE and in TNBC pts. This justifies further evaluation in a phase III study enrolling stage IIb/III pts not eligible for trastuzumab treatment and the very high risk TNBC group. Clinical trial information: NCT00524277.

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.

Algal supplementation of vegetarian eating patterns improves plasma and serum docosahexaenoic acid concentrations and omega-3 indices: a systematic literature review

BACKGROUND

Vegetarians are likely to have lower intakes of preformed docosahexaenoic acid (DHA) than omnivorous populations who consume fish and animal products. As such, vegetarian populations have omega-3 indices up to 60% lower than those who consume marine products. Algae, the primary producer of DHA in the marine food chain, offer an alternative source of DHA for those who do not consume marine or animal products. This systematic review aims to examine the evidence for the relationship between supplementation with algal forms of DHA and increased DHA concentrations in vegetarian populations.

METHODS

The SCOPUS, Science Direct and Web of Science scientific databases were searched to identify relevant studies assessing the effect of algal DHA consumption by vegetarian (including vegan) populations.

RESULTS

Four randomised controlled trials and two prospective cohort studies met the inclusion criteria. All included studies reported algal sources of DHA significantly improve DHA concentrations (including plasma, serum, platelet and red blood cell fractions), as well as omega-3 indices, in vegetarian populations. An evident time or dose response was not apparent given the small number of studies to date.

CONCLUSIONS

Future studies should address long chain n-3 polyunsaturated fatty acid deficiencies in vegetarian populations using algal DHA and explore the potential physiological and health improvements in these individuals.

A novel cancer vaccine platform utilizing autologous tumor lysate loaded into capped yeast cell wall particles

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Background: Our current tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine employs yeast cell wall particles (YCWP) to deliver antigen to DC ex vivo and is being tested in a randomized phase IIb trial. This strategy may be improved by injecting TL-loaded YCWP as an intradermal vaccine, with in vivo DC uptake. Silicate capping should allow YCWP to retain TL longer and stimulate DC uptake. Here, we present preclinical data on the tumor lysate, particle only (TLPO) vaccine concept vs. TLPLDC. Methods: To test the TLPO concept, YCWP were loaded with fluorescence (flr) labeled albumin and capped (cp) vs. uncapped (ucp) particles were compared for flr leak. Next, YCWP were added to cultured macrophages to evaluate DC uptake. Cells were then lysed, centrifuged, and flr in the cytoplasm vs. organelles measured. 3 C57B mice were then injected with 100ml NaCl, 106empty cp YCWP, or 1mcg GM-CSF. 5 hours (hr) post-injection, 100ml NaCl was injected into the same site, withdrawn, and examined via microscope to count monocytes. TLPO was compared to TLPLDC in a B16 murine melanoma survival model. Finally, 4 grey horses with equine melanoma were treated with autologous TLPO, injected biweekly for 4 vaccinations. Target lesions were assessed over 6 months. Results: Compared to ucp YCWP, cp had decreased flr leak at 1 (15.8% vs. 24.7%) and 2 hr (6.7% vs. 16.6%), increased uptake by DC (2hr flr readings 11065 vs. 3928) and higher delivery to DC cytoplasm (68.9% vs. 48.8%). Empty cp YCWP showed increased recruitment of monocytes (276/hpf) vs. GM-CSF (55/hpf) or NaCl alone (18/hpf). In the B16 murine melanoma model, the median survival time in days was 21 for controls (n=5), 42 for TLPLDC (n=10), and 56 for TLPO (n=20). At 6 months, the equine model revealed 1 complete and 3 partial responses (50%, 68%, and 45% tumor reduction). Conclusions: Silicate capping of the YCWP effectively limits leakage of contents, improves uptake by DC and delivery to the cytoplasm without the need for GM-CSF. In early animal studies, TLPO appears to have equivalent efficacy to TLPLDC, but eliminates the need for in vitro DC loading. We plan to perform a bridging study comparing TLPO to TLPLDC after enrollment is complete in our phase IIb TLPLDC melanoma trial.

Abstract P6-10-04: Determining the optimal vaccination strategy using a combination of the folate binding protein (FBP) peptide vaccine (E39+GM-CSF) and an attenuated version (E39') to maximize the immunologic response in breast cancer patients

BACKGROUND FBP is overexpressed in 20-50% of breast(B) cancers(Ca) and roughly 90% of endometrial(E) and ovarian (Ov) Ca. E39 (FBP191-199, EIWTHSYKV)+GM-CSF is an HLA-A2 restricted FBP peptide vaccine, which has been shown to generate significant in vivo immunologic response(IR) in a phase I/IIa trial in E Ca and Ov Ca patients (pts). There is a risk of inducing immunologic tolerance after multiple inoculations with a highly immunogenic vaccine. Thus, we are investigating a novel vaccination series using combinations of E39 and E39' (EIWTFSTKV, an attenuated version of E39) in a phase Ib, randomized, single-center trial. We are assessing short and long-term IR. Here, we present the initial IR analysis to the primary vaccination series (PVS) within B Ca pts.

METHODS HLA-A2 positive B or Ov Ca pts were enrolled after completion of standard of care therapy and randomized into three arms: EE (6 inoculations of E39); EE'(3 inoculations of E39, then 3 of E39'); or E'E(3 of E39', then 3 of E39). Theoretically, due to lower FBP expression and less aggressive chemotherapy regimens, B Ca pts are more antigen naïve and have a less suppressed immune system. Thus, only B Ca pts were included in this analysis. The PVS includes 6 inoculations total (R1-R6), one every 3-4 weeks, and containing 250mcg GM-CSF+500mcg peptide in the first 5 pts per arm and 1000mcg of peptide in second 5 pts. To assess the in vivo IR, local reaction(LR) was measured 48 hours after each inoculation (R1-R6), and delayed type hypersensitivity(DTH) was measured pre-PVS (R0), 1, and 6-months post-PVS (RC1, RC6). Ex vivo IR was measured via dextramer assay for E39-specific CD8+ T-cells at R0, RC1, and RC6. Statistical analyses were completed using appropriate tests.

RESULTS Thirty-five B Ca pts were enrolled, with 27 completing the PVS (EE n=10, EE' n=8, E'E n=9). No clinicopathologic differences between groups or significant toxicities &gt; grade 2 were appreciated. LR increased from R1 to R6 in all groups (ΔEE= 24.80mm, p=0.14; ΔEE'=38.13mm, p=0.07; ΔE'E=8.05mm, p=0.38), the greatest increase approaching statistical significance in the EE' arm. The only arm with a statistically significant increase for in vivo DTH from R0-RC1-RC6 was in the EE' arm (ΔEE=-6.17mm, p=0.27; ΔEE'= 44.58mm, p&lt;0.05; ΔE'E=-1.42, p=0.37). Ex vivo analysis of IR revealed no significant difference between groups at R0(p=0.45) or RC6(p=0.72), nor within groups over time (EE p=0.32, EE' p=0.47, E'E p=0.30).

CONCLUSION In this phase Ib trial analyzing the IR of B Ca pts receiving a different vaccination strategy, both peptides were noted to be safe and immunogenic. While no difference was seen in E39-specific CD8+ T cells between groups, the in vivo response was enhanced with the use of E39' after E39; this may indicate expansion of more effective clonal populations of CD8+ T cells with this strategy. These results may be specific to B Ca pts who are relatively antigen-naïve with relatively intact immune systems. Further analysis of these pts as this trial continues will determine the optimal vaccination strategy capable of stimulating and maintaining an IR to prevent B Ca recurrence.

Citation Format: Jackson DO, Qiao N, Peace KM, Hale DF, Vreeland TJ, Greene JM, Berry JS, Trappey AF, Clifton GT, Ibrahim N, Toms A, Peoples GE, Mittendorf EA. Determining the optimal vaccination strategy using a combination of the folate binding protein (FBP) peptide vaccine (E39+GM-CSF) and an attenuated version (E39') to maximize the immunologic response in breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-10-04.

Abstract OT3-01-04: VADIS trial: Phase II trial of the nelipepimut-S peptide v accine in women with DCIS of the breast

Background: Our group has been investigating vaccination strategies in breast cancer. Specifically, we have been evaluating HER2-derived peptide vaccines including nelipepimut-S+GM-CSF administered adjuvantly to breast cancer patients who have been rendered disease-free with standard of care therapy but are at high risk for recurrence. Early phase clinical trials showed an approximately 50% reduction in relative recurrence risk in vaccinated patients. Based on these data, nelipepimut-S+GM-CSF is being evaluated in a phase III registration trial. Having shown the vaccine to be safe, effective in stimulating an antigen-specific immune response and potentially having clinical efficacy in the setting of secondary prevention, the current study was initiated to evaluate vaccination in DCIS patients. This trial represents an initial step to move the vaccine into the primary prevention setting.

Trial Design: Phase II, randomized, single-blind study. Patients will be randomized 2:1 to receive vaccine or GM-CSF alone. After enrollment, patients will receive 3 inoculations administered every other week preoperatively followed by surgery then completion of the vaccination series (3 additional inoculations) in the adjuvant setting.

Eligibility: The trial will enroll pre- or post-menopausal women with a diagnosis of DCIS made by core biopsy. The area of radiographic abnormality must measure at least 1 cm. Because the vaccine is a MHC class I, CD8+ T cell-eliciting vaccine, it is HLA restricted, and patients must be HLA-A2+ to enroll. Participants must also have an ECOG performance status &lt;2, adequate cardiac, kidney and liver function and be willing to comply with all study interventions and follow-up procedures.

Specific Aims: The trial's primary endpoint is to evaluate for nelipepimut-specific CD8+ T cells in the peripheral blood of vaccinated patients compared to patients receiving GM-CSF alone. Secondary endpoints include evaluating toxicity; determining the immune response in vivo by DTH, in vitro by evaluating for epitope spreading to other tumor antigens, and importantly in the tumor by assessing the degree of lymphocytic infiltration in surgically resected specimens. The extent of HER2 expression, Ki67 and cleaved caspase 3 in the resected specimen will also be assessed.

Statistical Methods: A total of 108 DCIS patients will be consented and screened for eligibility. 48 (45%) are expected to be HLA-A2 positive. These 48 patienst will be randomized 2:1 to vaccine or GM-CSF alone groups. Accounting for 10% attrition rate and for an approximately 5% non-evaluable sample rate, we expect to have 40 evaluable patients, 27 in the vaccine group and 13 in the GM-CSF alone group, that have baseline, pre-surgery, and post-surgery measures of nelipepimut-S-specific CD8+ T cells. We will have 82% power to detect a significant increase in nelipepimut-S-specific CD8+ T cells in the vaccine group versus the GM-CSF alone group.

Contact Info: The study is accruing at four sites to include Columbia University, Dana Farber Cancer Institute, MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center. Additional information can be obtained from the overall study PI, Dr. Elizabeth Mittendorf (eamitten@mdanderson.org). NCT0236582.

Citation Format: Mittendorf EA, Plitas G, Garber J, Crew K, Heckman-Stoddard B, Wojtowicz M, Vornik L, Peoples GE, Brown PH. VADIS trial: Phase II trial of the nelipepimut-S peptide vaccine in women with DCIS of the breast [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-01-04.

Gaining ground on a cure through synergy: combining checkpoint inhibitors with cancer vaccines

INTRODUCTION

The approval of multiple checkpoint inhibitors (CPIs) for the treatment of advanced malignancies has sparked an explosion of research in the field of cancer immunotherapy. Despite the success of these medications, a large number of patients with advanced malignancy do not benefit from therapy. Early research indicates that a therapeutic combination of cancer vaccines with checkpoint inhibitors may lead to synergistic effects and higher response rates than monotherapy. Areas covered: This paper summarizes the previously completed and ongoing research on this exciting combination, including the use of the tumor lysate, particle-loaded dendritic cell (TLPLDC) vaccine combined with checkpoint inhibitors in advanced melanoma. Expert commentary: Increasing experience with CPIs has led to improved understanding of which patients may benefit and it is increasingly clear that the presence of a pre-existing immune response to the tumor, along with tumor-infiltrating lymphocytes, is key to the success of CPIs. One exciting possibility for the future is the addition of a cancer vaccine to CPI therapy, eliciting these crucial T cells, which can then be augmented and protected by the CPI. A number of current and future studies are addressing this very exciting combination therapy.

Primary analysis of a prospective, randomized, single-blinded phase II trial evaluating the HER2 peptide AE37 vaccine in breast cancer patients to prevent recurrence

BACKGROUND

AE37 is the Ii-Key hybrid of the MHC class II peptide, AE36 (HER2 aa:776-790). Phase I studies showed AE37 administered with granulocyte macrophage colony-stimulating factor (GM-CSF) to be safe and highly immunogenic. A prospective, randomized, multicenter phase II adjuvant trial was conducted to evaluate the vaccine's efficacy.

METHODS

Clinically disease-free node-positive and high-risk node-negative breast cancer patients with tumors expressing any degree of HER2 [immunohistochemistry (IHC) 1-3+] were enrolled. Patients were randomized to AE37 + GM-CSF versus GM-CSF alone. Toxicity was monitored. Clinical recurrences were documented and disease-free survival (DFS) analyzed.

RESULTS

The trial enrolled 298 patients; 153 received AE37 + GM-CSF and 145 received GM-CSF alone. The groups were well matched for clinicopathologic characteristics. Toxicities have been minimal. At the time of the primary analysis, the recurrence rate in the vaccinated group was 12.4% versus 13.8% in the control group [relative risk reduction 12%, HR 0.885, 95% confidence interval (CI) 0.472-1.659, P = 0.70]. The Kaplan-Meier estimated 5-year DFS rate was 80.8% in vaccinated versus 79.5% in control patients. In planned subset analyses of patients with IHC 1+/2+ HER2-expressing tumors, 5-year DFS was 77.2% in vaccinated patients (n = 76) versus 65.7% in control patients (n = 78) (P = 0.21). In patients with triple-negative breast cancer (HER2 IHC 1+/2+ and hormone receptor negative) DFS was 77.7% in vaccinated patients (n = 25) versus 49.0% in control patients (n = 25) (P = 0.12).

CONCLUSION

The overall intention-to-treat analysis demonstrates no benefit to vaccination. However, the results confirm that the vaccine is safe and suggest that vaccination may have clinical benefit in patients with low HER2-expressing tumors, specifically TNBC. Further evaluation in a randomized trial enrolling TNBC patients is warranted.

Primary analysis of the prospective, randomized, phase II trial of GP2+GM-CSF vaccine versus GM-CSF alone administered in the adjuvant setting to high-risk breast cancer patients

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Background: GP2 is a HER2 derived, HLA-A2+-restricted immunogenic peptide designed to stimulate CD8+T cells to recognize tumor cells with any level of HER2 expression (IHC 1-3+). Accrual to a prospective, randomized, multi-center, phase II trial of the GP2 vaccine for prevention of breast cancer recurrence has completed. Here, the planned primary analysis of disease-free survival (DFS) is presented. Methods: HLA-A2+ node positive or high-risk node negative breast cancer patients (pts) with any level of HER2 expression rendered disease-free by standard of care therapy (to include trastuzumab where appropriate) were randomized to receive GP2+GM-CSF (VG) or GM-CSF (CG) alone. Pts received 6 monthly inoculations (primary vaccine series = PVS) followed by 4 boosters administered every 6 months. The Kaplan Meier method was used for statistical analysis. The intention-to-treat (ITT) population is defined as the entire randomly assigned population. The per-treatment (PT) group excluded pts who recurred during the PVS or developed a second malignancy. A pre-specified subgroup analysis was performed based on HER2 expression level. HER2 overexpression (OE) is defined as IHC 3+or FISH >2.2. Results: With 89 VG and 91 CG pts enrolled and vaccinated, there are no differences between groups with respect to age, node positivity, tumor size, grade, ER/PR status, and HER2 expression (p>0.05). The vaccine has been well tolerated with toxicities comparable between the VG and CG. Only one grade 3 local and systemic toxicity reaction has been reported in the VG. At 34 (1-60) month median follow-up, DFS was compared in the ITT (85% VG v 81% CG, p = 0.57) and PT (94% VG v 85% CG, p = 0.17) populations. In OE patients (51 VG and 50 CG) DFS was 94% VG v 89% CG, p = 0.86 (ITT) and 100% VG v 89% CG, p = 0.08 (PT). Conclusions: GP2+GM-CSF is a novel vaccine that is safe and well tolerated. This phase II trial demonstrates potentially greater benefit in pts with HER2 OE tumors, in whom there have been no recurrences in the PT group. This may be due to synergism with trastuzumab therapy, thus justifying a phase III trial evaluating GP2 administered in the adjuvant setting to a HER2 OE population. Clinical trial information: NCT00524277.

Final report of the phase I/II clinical trial of the E75 (nelipepimut-S) vaccine with booster inoculations to prevent disease recurrence in high-risk breast cancer patients

BACKGROUND

E75 (nelipepimut-S) is a human leukocyte antigen (HLA)-A2/A3-restricted immunogenic peptide derived from the HER2 protein. We have conducted phase I/II clinical trials vaccinating breast cancer patients with nelipepimut-S and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the adjuvant setting to prevent disease recurrence. All patients have completed 60 months follow-up, and here, we report the final analyses.

PATIENTS AND METHODS

The studies were conducted as dose escalation/schedule optimization trials enrolling node-positive and high-risk node-negative patients with tumors expressing any degree of HER2 (immunohistochemistry 1-3+). HLA-A2/3+ patients were vaccinated; others were followed prospectively as controls. Local and systemic toxicity was monitored. Clinical recurrences were documented, and disease-free survival (DFS) was analyzed by Kaplan-Meier curves; groups were compared using log-rank tests.

RESULTS

Of 195 enrolled patients, 187 were assessable: 108 (57.8%) in the vaccinated group (VG) and 79 (42.2%) in the control group (CG). The groups were well matched for clinicopathologic characteristics. Toxicities were minimal. Five-year DFS was 89.7% in the VG versus 80.2% in the CG (P = 0.08). Due to trial design, 65% of patients received less than the optimal vaccine dose. Five-year DFS was 94.6% in optimally dosed patients (P = 0.05 versus the CG) and 87.1% in suboptimally dosed patients. A voluntary booster program was initiated, and among the 21 patients that were optimally boosted, there was only one recurrence (DFS = 95.2%).

CONCLUSION

The E75 vaccine is safe and appears to have clinical efficacy. A phase III trial evaluating the optimal dose and including booster inoculations has been initiated.

CLINICAL TRIALS

NCT00841399, NCT00584789.

Abstract P4-13-02: Preliminary results for the phase 1 trial of a dual HER2 peptide cancer vaccine in breast and ovarian cancer patients

BACKGROUND: HER2 is a commonly expressed tumor-associated antigen in breast (BrCa) and ovarian cancer (OvCa) and, therefore, an attractive target for immunotherapy. We have investigated HER2-derived peptides as vaccines mixed with GM-CSF to include GP2 (a HLA-A2 and HLA-A3 restricted, CD8+ eliciting epitope) and AE37 (a HLA unrestricted, MHC class II, CD4+ eliciting epitope). Both peptide vaccines (PV) have shown clinical promise individually. There is clear rationale for combining GP2 and AE37 to elicit a more robust immune response (IR) of both CD4+ and CD8+ T cells. Here, we summarize initial toxicity (tox) and in vivo IR data from a phase 1 trial of the combined PV.

METHODS: The trial is being performed as a five cohort, 3+3 dose-escalation, safety trial. Clinically disease-free, HLA-A2+ and A3+, BrCa and OvCa patients with tumors expressing any level of HER2 (IHC 1-3+) and who have completed standard-of-care therapy are accrued. In the first cohort, three patients received six, monthly intradermal inoculations (R1-R6) of 100mcg of AE37, 100mcg of GP2, and 125mcg of GM-CSF or 100:100:125. The second cohort received 250mcg of AE37, 100mcg of GP2, and 125mcg of GM-CSF or 250:100:125. Three additional cohorts were vaccinated: 250:250:125, 500:250:125, and 500:500:125. Toxicity was graded 48-72 hours post vaccination using NCI Toxicity Criteria v4.0. After each inoculation, local reactions (LR) are measured via the sensitive ballpoint pen method and reported as the orthogonal mean (OM). IR is assessed in vivo by delayed type hypersensitivity (DTH) reactions with separate intradermal inoculations of AE37, AE36, and GP2 antigens, measured both pre-vaccination (R0) and after the vaccine series (R6) via the sensitive ballpoint pen method, and reported as the OM. Means were compared using paired t-tests.

RESULTS: 28 patients enrolled; 8 withdrew consent, 1 recurred prior to completing R6, 3 had an intercurrent illness, 14 patients completed R1-R6, and the vaccine series is ongoing in 2 patients. Six patients did not receive any inoculations and, therefore, are not included in this safety analysis. In 22 patients, the vaccine was well tolerated (max local tox: 23% Grade (Gr) 1, 73% Gr 2, 4% Gr 3; max systemic tox: 14% Gr 0, 50% Gr 1, 36% Gr 2). No dose-limiting toxicity was observed. For the 14 patients who completed the VS, the median age was 51(35-83). Breast tumor size was 3.3±1.1cm and ovarian tumor size was 10.0±2.3cm. Compared to GP2 LR at R1 (15.5±4.1mm), LR increased at R2 (31.7±5.9mm), R3 (42.9±7.4mm), R4 (35.3±7.3mm), R5 (45.0±9.9mm), and R6 (25.9±6.7mm, p = 0.17). Compared to the AE37 LR at R1 (18.5±3.8mm), LR increased at R2 (37.3±6.7mm), R3 (36.4±4.6mm), R4 (42.2±5.9mm), R5 (46.0±8.9mm), and R6 (36.2±6.6mm). Unless stated, all LR p-values &lt; 0.05. After the VS, AE37 DTH increased from 0.0±0.0mm to 19.6±6.7mm (p&lt;0.01), AE36 DTH increased from 0.0±0.0mm to 10.3±3.9mm (p&lt;0.01), and GP2 DTH reactions increased from 0.3±0.2mm to 4.1±2.0mm (p = 0.056).

CONCLUSIONS: Initial results from a phase I trial of a vaccine combining GP2 and AE37 peptides show that dual administration of the peptides is well tolerated at all tested dosing levels. Additionally, the combination is capable of stimulating strong peptide-specific in vivo immune responses. Continued testing of this vaccination strategy is underway.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-13-02.

Abstract P4-13-05: HLA-A2 is not a prognostic indicator in breast cancer: Implications for cancer vaccine trials

Introduction

Peptide-based cancer vaccines require presentation by a specific HLA molecule. HLA-A2 is the most common class I allele in the US (40-50% of the population) and, therefore, the most commonly targeted. Our group has been investigating HER2-derived peptide vaccines administered in the adjuvant setting to high risk breast cancer patients in order to prevent disease recurrence. This study was undertaken to compare known prognostic factors and disease-free survival (DFS) in control HLA-A2+ and HLA-A2- patients in order to better define these populations for future trial design.

Methods

Our group is currently enrolling patients in a phase II trial evaluating the HER2-derived peptide vaccines, AE37 (MHC Class II, HLA-non-restricted epitope) and GP2 (MHC Class I, HLA-A2+ restricted epitope). The studies are enrolling high-risk, disease-free breast cancer patients with any level of HER2 expression (IHC 1+, 2+ or 3+) after completion of standard of care therapy. Patients are HLA-typed. HLA-A2+ patients are randomized to GP2+GM-CSF or GM-CSF alone. HLA-A2- patients are randomized to AE37+GM-CSF or GM-CSF alone. Demographics between groups are compared using chi squared or fisher exact as appropriate. DFS is compared using log rank.

Results

Thus far, 407 patients have been enrolled to the study (181 HLA-A2+ and 226 HLA-A2-). Demographics are shown in Table 1.

Table 1. Demographics (all) A2+A2-pn181226 Age (median)51500.47Node Positive62%66%0.46Grade 354%54%0.99Tumor &gt;/ = 2 cm59%64%0.23ER/PR Negative36%38%0.59HER2 Overexpression55%51%0.39Triple Negative13%15%0.52

There are no differences between groups with respect to age, node positivity, grade, tumor size, ER/PR status, HER2 over-expression, or triple negative breast cancer. Of those enrolled, 83 HLA-A2+ patients and 109 HLA-A2- patients have been randomized to the control groups. Within the control group, there are no differences between the HLA-A2+ and HLA-A2- patients regarding age, node positivity, grade, tumor size, ER/PR status, HER2 over-expression, or triple negative breast cancer (Table 2).

With a median follow-up of 30 months, DFS is similar between A2+ and A2- control patients (83% v. 80%, p = 0.93).

Conclusions

Baseline clinico-pathologic factors are similar between HLA-A2+ and HLA-A2- breast cancer patients with no correlations to known prognostic factors. Well-matched blinded control patients treated only with GM-CSF demonstrate no differences in DFS between HLA-A2+ and HLA-A2- patients. Therefore, it does not appear that HLA-A2 status is a prognostic factor in breast cancer, and HLA-A2+ and HLA-A2- patients should be comparable in peptide-based breast cancer vaccine trials.

Table 2. Demographics (Control Group Only) A2+A2-pn83109 Age (median)51510.75Node Positive65%64%0.99Grade 359%57%0.76Tumor &gt;/ =59%71%0.08ER/PR Negative36%38%0.84HER2 Overexpression55%46%0.19Triple Negative11%16%0.34

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-13-05.

Abstract P2-14-01: Breast cancer patients with HER2 low-expression: An under-recognized group at significant risk for recurrence

Background:

HER2 over-expression is associated with more aggressive malignant disease. The introduction of trastuzumab and other HER2-directed therapies, however, has led to improved prognosis for patients (pts) with HER2 over-expressing (OE) tumors. Currently, no HER2-targeted therapies are available for patients with HER2 low-expressing (LE) (1+, 2+ by IHC) tumors. We are conducting a randomized, controlled Phase II trial of multiple peptide vaccines enrolling patients with any level of HER2 expression (1+, 2+ and 3+). Here, we report survival data based on levels of HER2 expression in our unvaccinated, control pts.

Methods:

After standard of care therapy, disease-free, high-risk BCa pts were randomized to receive either peptide+GM-CSF (Vaccine Group, VG) or GM-CSF alone (Control Group, CG) in six, monthly doses followed by four boosters every six months. Pts were prospectively followed for recurrence. Demographic information was available for all pts and was compared between groups using chi square or fisher exact tests. Disease-Free Survival (DFS) was compared using log rank.

Results:

To date, we have enrolled 196 pts in the CG. 96 pts had HER2 OE tumors, 100 had LE tumors. The only significant demographic difference between the CG OE and LE groups was more ER/PR positive patients in LE (LE 72% vs OE 51%, p = 0.008). 83% of CG OE pts received trastuzumab, 3% of CG LE pts received trastuzumab. At a median f/u of 30 mo, DFS was significantly higher for CG OE vs CG LE (92.5% v 65.5%, p = 0.001).

Conclusions:

In the cohort of control pts from our ongoing vaccine trial, conducted in an era when Tz has been standard of care therapy for patients with HER2 OE tumors, we have shown that HER2 LE pts are at higher risk of recurrence than OE pts, despite having more ER/PR positive. This calls for increased efforts to develop novel therapies for patients with HER2 LE disease. We have previously shown a trend towards increased DFS with the HER2 vaccines, AE37 (p = 0.13, median f/u 22 mo) and E75 (p = 0.16, median f/u 60mo) in HER2 LE pts, suggesting that these vaccines may represent one such novel therapeutic approach.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-14-01.

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

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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. Clinical trial information: NCT00524277.

Time-dependent estimates of recurrence and survival in colon cancer: clinical decision support system tool development for adjuvant therapy and oncological outcome assessment

e14500

Background: Unanswered questions remain regarding treatment efficacy in colon cancer (CC), especially those determining high-risk node-negative cohorts that may benefit from adjuvant therapy. We sought to evaluate the use of machine learning and classification modeling to estimate survival and recurrence in CC. Methods: We used the Department of Defense Automated Central Tumor Registry (ACTUR) to identify primary CC patients treated between January 1993 and December 2004. Cases with events or follow-up that passed quality control were stratified into one-, two-, three-, and five-year survival cohorts. ml-BBNs were trained using machine-learning algorithms and k-fold cross-validation, and receiver operating characteristic (ROC) curve analysis used for validation. Results: There were 5,301 cases stratified into cohorts. Survival cohort Areas-Under-the-Curve (AUCs) ranged from 0.85–0.90, positive-predictive-values (PPVs) for recurrence and mortality ranged from 78-84% and negative-predictive-values (NPVs) from 74-90%. Cross-validation showed that the ml-BBNs produce robust individual estimates of recurrence (p<0.001) and mortality (p<0.001) based on readily available clinical-pathological information in the context of adjuvant chemotherapy. Conclusions: Tumor registry data and machine-learned Bayesian Belief Networks produce robust classifiers. These Clinical Decision Support System tools yield clinically relevant estimates of outcomes that may assist clinicians in treatment planning.

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

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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. Clinical trial information: NCT00524277.

Safety and efficacy of the HER2-derived GP2 peptide vaccine in combination with trastuzumab for breast cancer patients in the adjuvant setting

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Background: GP2 is a 9 amino acid HLA-A2/A3 restricted HER2-derived peptide. GP2 + GM-CSF has been shown to be safe and effective in eliciting anti-HER2 immune response in breast cancer patients. Preclinical data has demonstrated that pretreatment of cells with trastuzumab (Tz) enhances susceptibility to lysis by GP2-specific cytotoxic T lymphocytes (CTLs). We conducted a phase Ib study to evaluate the combination of the GP2 vaccine and Tz. Methods: HLA-A2/A3 + patients with HER2 overexpressing breast cancer receiving Tz as standard therapy were enrolled. The study was designed as a 3+3 dose escalation trial with an expansion cohort evaluating 4 dose levels of the vaccine administered as 6 inoculations given every 3 weeks in combination with Tz (6mg/kg). Toxicity was graded 48-72 hr post vaccination using NCI Toxicity Criteria. Ejection fraction (EF) was monitored every 3 mo. Immunologic response was assessed in vivo by injection site local reaction (LR) and in vitro by quantifying the number of GP2-specific CTLs by HLA-A2: IgG dimer assays and their functional activity by ELISPOT. Results: 19 patients enrolled (median age 47 yr, mean tumor size 3.4 cm, 74% were grade 3, 53% ER/PR+, 63% node positive, 74% received anthracycline based therapy). Maximum local toxicities were grade 1 (77% of patients) and grade 2 (6%), and maximum systemic toxicities were grade 1 (24%) and grade 2 (5%). There were no grade 3 or 4 local or systemic toxicities. There was no significant change in EF at 3 mo (57± 1%, p=0.23) or 6 mo (59±1%, p=0.8) compared to baseline (58±0.9%). Mean post-vaccine series LR was significantly larger than initial vaccination LR (68.2 ± 8.6 mm vs 28.0 ± 10.3 mm, p=0.0004). In vitro assays demonstrated an increase in the maximal number of post- versus pre-vaccination GP2-specific CTLs by dimer assay (1.45 ± 0.19 vs 0.96 ± 0.19%, p=0.06) and increased ELISPOT activity [median 86 range (3-194) vs 34 (range 0-295) spots/106 cells]. Conclusions: GP2 vaccine in combination with Tz is both safe and immunogenic in HER2-overexpressing breast cancer patients in the adjuvant setting. Toxicity was limited to mild local and systemic reactions. There were no dose limiting toxicities or cardiac events.

Randomized phase II clinical trial of the anti-HER2 (GP2) vaccine to prevent recurrence in high-risk breast cancer patients: A planned interim analysis

3005

Background: A prospective, randomized, multi-center, placebo-controlled, single-blinded, phase II trial was designed to evaluate the safety and clinical efficacy of GP2, a HER2-derived peptide vaccine, in breast cancer patients. Methods: Clinically disease-free, node-positive or high-risk node-negative patients (pts) with any level of HER2 expression were enrolled after standard of care therapy. HLA-A2+ pts were randomized to receive GP2 + GM-CSF (VG) or GM-CSF alone (CG). HLA A2- controls from a parallel arm of the study were also eligible for evaluation, the extended CG (ECG). Pts receive 6 monthly intradermal inoculations (R0-R6) during the primary vaccine series followed by four boosters every 6 mos. Immune responses (IR) were measured by delayed type hypersensitivity (DTH) at R0 and R6. This planned interim analysis was performed at 24 months median follow-up. Results: We have currently enrolled 172 pts (46, VG; 43, CG; 83 extended CG). There are no differences between groups with respect to age, rate of node positivity, tumor grade, tumor size, ER/PR status, and HER2 over-expression (all p > 0.05). Maximum local toxicity (tox) was similar between the two groups (grade (Gr) 1 and 2: VG 93%, CG 98%; Gr 3: VG 2%, CG 1%). Maximum systemic tox was also similar between the groups (Gr 1 and 2: VG 91%, CG 85%). No Gr 3 systemic tox has been reported. The most frequent systemic reactions are fatigue, headache, and myalgias. IR to GP2 has been robust. DTH is increased from R0 to R6 in the VG (3.0±0.98 to 21.5±4.04 mm, p < 0.01) vs. the smaller increase in CG (2.6±0.89 to 6.0±1.6 mm, p = 0.01). VG DTH at R6 is significantly higher than the CG (21.5 vs 6.0 mm, p < 0.01). The recurrence rate (RR) is decreased in the VG vs CG (4.3% vs. 11.6%, p = 0.41) and VG vs ECG (4.3% vs 9.5%, p = 0.41). In pts with HER2-overexpressing (IHC3+ or FISH+) tumors, the RR is decreased in the VG (0% vs 5% CG, p = 0.28). For TNBC (HER2 low, ER/PR-) pts, the RR is reduced in the VG vs ECG (0% vs 10.6%, p = 0.251). Conclusions: The GP2 vaccine is safe and the minimal toxicity is comparable between the VG and CG, suggesting that it is due to GM-CSF. Robust in vivo immune response has correlated with a >50% reduction in breast cancer recurrences in the VG. Clinical trial information: NCT00524277.

Biomarker correlation to clinical response in phase I/II trials of the adjuvant breast cancer vaccine neuvax (nelipepimut-S or E75)

TPS3126

Background: We completed phase I/II clinical trials with NeuVax (nelipepimut-S), a HLA-A2/A3-restricted, HER2-derived peptide vaccine. The vaccine was administered in the adjuvant setting to prevent recurrence in breast cancer patients rendered disease-free with standard-of-care therapy. Here, we examine the relationship between in vitro immunologic response (IR) and clinical recurrence (CR) after 5-year follow-up. Methods: The phase I/II trials were performed as dose-escalation/schedule-optimization trials enrolling node positive and high-risk, node-negative patients (pts) with tumors expressing any level of HER2 (IHC 1+,2+,or 3+). HLA-A2/A3+ pts were enrolled in the vaccine group (VG) while HLA-A2/A3- pts were followed prospectively as an untreated control group (CG). The VG was given 4-6 monthly intradermal inoculations of nelipepimut-S+GMCSF (immunoadjuvant) during the primary vaccine series (PVS). In vitro IR was assessed for E75-specific, cytotoxic T lymphocyte clonal expansion by HLA-A2:IgG dimer assay and expressed as mean dimer index (mdi) at baseline, after PVS (R6), and six months after the PVS. HER2 under-expression was defined as an IHC 1/2, and a FISH < 2.2. VG and CG pts were followed for CR over 60 months. P-values were calculated using the Fisher’s exact test. Results: Of the 195 pts enrolled, 8 withdrew, leaving 187 evaluable pts; 108 in the VG and 79 in the CG. R6 dimer assays were available for 86 pts in the VG. The mean R6 dimer in the VG is 0.63 mdi+.08. Of the 30 pts with an R6 dimer above the mean, only one recurred, compared to eight of the 56 below the mean (p=.09). The difference between baseline and maximum mdi was available in 56 HER2 under-expressing VG pts. Of the 26 pts above the mean difference (1.08 mdi +.17), one recurred, compared to six CR in the 30 pts below the mean (p=.06). There were no CR in pts with HER2 under expression with a mean difference ranked in the top third. Conclusions: In prospective, completed phase I/II trials of NeuVax (nelipepimut-S), patients who exhibit robust in vitro IR have lower recurrence rates. This finding suggests that nelipepimut-specific CTL clonal expansion is a valid biomarker for CR in pts treated with NeuVax. Clinical trial information: NCT00841399.

Abstract P5-16-05: The combination of trastuzumab and HER2-directed peptide vaccines is safe in HER2-expressing breast cancer patients

Background: Cardiotoxicity is the most concerning toxicity associated with the commonly used HER2-directed immunotherapy, trastuzumab (Tz). In general, a significant decline of left ventricular ejection fraction (EF) in asymptomatic patients is accepted as a decrease of at least 10% or an absolute value of below 50%. We are currently conducting multiple trials of HER2-directed peptide vaccines, often given either concurrently or in close temporal proximity to Tz. This has raised the issue that combining therapies could increase the risk of cardio-toxicity. Here, we present safety data from multiple trials in which the combination of these HER2-directed therapies was administered.

Methods: Phase I and II trials were conducted in disease-free breast cancer patients after completion of chemotherapy when indicated. Patients (pts) who were determined by treating oncologists to qualify for Tz received this therapy per standard-of-care. These pts were enrolled onto HER2-directed peptide vaccine trials per each trial's inclusion criteria, with vaccinated (VG) pts receiving peptide + GM-CSF and control (CG) pts receiving GM-CSF alone. All patients were monitored for local and systemic toxicity to peptide inoculations (graded by the NCI's Common Terminology Criteria for Adverse Events). In addition, patients who received Tz had EF tracked through either echocardiogram or MUGA according to local standard of practice. Our database was queried for patients who received Tz and peptide, and had documented measures of EF pre-vaccine (Pre), during vaccine (D) and post-vaccine (Post). These pts were then placed in two groups based on the timing of Tz and vaccine therapy: concurrent(C) group and sequential(S) group. Mean EF at each time point was compared using a t-test.

Results: Overall, the peptide vaccines were well tolerated (max local tox: 1% Grade 0, 65% Gr 1, 33% Gr 2, 1% Gr 3; max systemic tox: 19% Gr 0, 63% Gr 1, 18% Gr 2, 0% Gr 3). These toxicities are likely secondary to the GM-CSF immunoadjuvant as control pts receiving GM-CSF alone have similar toxicity profiles (max local tox: 0% Gr 0, 76% Gr 1, 23% Gr 2, 1% Gr 3; max systemic tox: 20% Gr 0, 65% Gr 1, 15% Gr 2, 0% Gr 3). There have been no serious or non-serious cardiac-related adverse events in our trials. In total, 71 pts treated with Tz and enrolled in a vaccine trial had EF measurements available for analysis; 54 in the S group (35 VG, 19 CG) and 17 in the C group (10 VG, 7 CG). Overall, neither VG nor CG pts had significant changes in EF (VG Pre: 65±0.8%, D: 63±0.9%, Post: 64±0.3%; CG Pre: 63±1.2%, D: 64±1.8%, Post: 63±1.1%). Separating VG pts into C and S pts, there were again no significant changes in EF, (C Pre: 65±1.0%, D: 63±1.0%, Post: 63±1.4%; S Pre: 65±1.7%, D: 61±1.3%, Post: 65±1.8%).

Conclusions: HER2-directed peptide vaccines are safe and well tolerated. Initial data indicate that the combination of Tz and HER2-directed peptide vaccines, whether concurrent or sequential, does not cause significant cardiac toxicities as measured by changes in the EF during and after therapy. We will continue to track this safety data to confirm early findings as we pursue additional combination trials.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-16-05.

Early efficacy analysis of the AE37 vaccine in patients with HER2 low-expressing and triple-negative breast cancer

109

Background: Peptide vaccines comprised of HLA class II epitopes, which elicit CD4+ T cell responses, play a critical role in potentiating immune responses. We are conducting a randomized phase II trial of AE37, a hybrid peptide created by the addition of the Ii-Key moiety (LRMK) to the HER2 helper epitope, AE36 (HER2 aa776-790). Here, we present efficacy data focusing on outcomes in patients with low HER2 (IHC 1+ or 2+) expression and triple negative breast cancer (TNBC). Methods: The trial is enrolling node positive or high risk node negative breast cancer patients with any degree of HER2 expression (IHC 1+, 2+ or 3+ or FISH > 1.2) rendered disease-free following standard of care therapy. Patients are randomized to receive either AE37+GM-CSF or GM-CSF alone in 6 monthly intradermal inoculations followed by booster inoculations administered every 6 months. Results: The trial has enrolled 254 patients; 105 in the vaccine group (VG) and 149 in the control group (CG). 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. Evaluating patients with low HER2 expression (IHC 1+ or 2+), there are 53 VG patients and 77 CG patients. The groups are well-matched with respect to the percentage of patients with high grade tumors, tumors > 2cm, the rate of node positivity and ER/PR status (all p>.5). The DFS rate in the VG of low HER2 expressers is 89.8% vs 68.2% in the CG (p=.12), a 68% risk reduction. When limiting analyses to patients with TNBC (ER/PR negative, HER2 1+ or 2+), there are 13 VG patients and 23 CG patients. The groups are again well-matched with the exception of control patients having a larger percentage of tumors > 2 cm (70% vs 31%; p=.02). The DFS rate in the VG of TNBC patients is 83.3% vs 47.6% in the CG (p=.23), a 68% risk reduction. Conclusions: Early analyses suggest clinical benefit to vaccination with AE37, particularly in patients with low HER2-expressing tumors. Importantly, the benefit appears to persist in TNBC patients. Patients will continue to be followed per protocol for 5 years; however, these data suggest that a subsequent phase III trial should evaluate the vaccine in patients with low HER2-expressing disease to include TNBC.

From bench to bedside: The use of the li-Key technology to improve helper peptides for clinical use in cancer vaccines

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Background: Work involving peptide vaccines has shown that peptides containing MHC Class II epitopes, which elicit CD4+ T cell responses, may play a role in potentiating an immune response. The Ii-Key peptide (amino acids 77-80 of the immune-regulatory Ii protein), when covalently linked to an MHC Class II epitope, can induce conformational change in the epitope binding groove, increasing CD4+ T cell stimulation up to 250 fold. Here we present an update of results from clinical trials evaluating this novel technology in an adjuvant breast cancer vaccine targeting HER2/neu. Methods: We reviewed our trials investigating AE37, a hybrid peptide created by the addition of the Ii-Key peptide (LRMK) to AE36 (GVGSPYVSRLLGICL), an MHC Class II-binding peptide from the intracellular domain of the HER2 protein. We have completed a phase I study and are currently conducting a randomized phase II trial of the AE37 peptide + GM-CSF in the adjuvant treatment of disease-free breast cancer patients with any level of HER2 expression (IHC 1-3+ or FISH>1.2). Results: Phase I data showed the vaccine to be safe and effective in raising anti-HER2 immunity. Importantly, even the cohort of patients given AE37 without GM-CSF showed significant increases in both in vivo and in vitro immune responses. To date, we have enrolled 201 patients to our phase II trial (Vaccine (VG)=103, Control (CG)=98). Toxicity has been minimal (99% of local and systemic toxicities grade ≤2). VG patients have shown significant increases in both in vivo and in vitro responses to both AE36 and AE37, with consistently stronger responses to the AE37 hybrid peptide than the native AE36. 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. Conclusions: The AE37 peptide vaccine appears to be effective in eliciting a strong immune response and possibly preventing breast cancer recurrence. These results provide an important proof of concept and suggest that additional studies evaluating Ii-Key hybrid peptide vaccines are warranted, whether in the field of immunotherapy or more traditional vaccines.

An assessment of disease features and immune response in breast cancer patients that did not recur after receiving HER2 peptide, AE37 vaccine in a randomized phase II trial

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Background: In a phase I trial of AE37, the Ii-Key hybrid of HER2 derived peptide AE36 (776-790), administered with immunoadjuvant GMCSF demonstrated the vaccine to be safe and capable of stimulating CD4+helper T cells with HER2 specific anti-tumor activity. Here we present analysis of immune markers and patient feature that may impact recurrence from an ongoing prospective, randomized, single-blinded Phase IIb trial of AE37+GMCSF v GMCSF alone in adjuvant high risk breast cancer (BC) patients. Methods: After completion of standard therapy; disease-free, node positive or high risk node negative BC patients (pts) were randomized to receive either AE37+GMCSF or GMCSF in 6 monthly intradermal inoculations. Immunologic responses were measured using [3H]-thymidine incorporation assay (in vitro), delayed-type hypersensitivity (DTH) reactions (in vivo) and T regulatory cells (Tregs). Among those vaccinated recurrent pts (VR) are compared to non recurrent (VNR) pts. Results: We have vaccinated 109 pts with 8.3% recurrence rate at 2 year median follow up. VR v VNR were younger (44 v 50 yo p=0.11), had higher grade (67% v 44% p=0.32), more ER/PR- (44% v 38% p=0.75), larger tumors (89% v 50% p=0.06), and node positive (89% v 70% p=0.37). No difference for HER2 status (IHC 3+, 44% v 49% p=0.64). Both VR and VNR responded to vaccine though the mean DTH and proliferative stimulation index was approximately 10% less in VR pts (18 v 20 p=0.73; 1.96 v 2.2 p=0.77 respectively). The most predictive measure was change in Tregs with VR pts less likely to decrease their Tregs levels (50% v 76% p=0.17) after vacination and more likely experience increased Tregs (17% v 8% p=0.48). A decrease in Tregs had an inverse trend towards recurrence (p=0.17). Conclusions: Preliminarily, it appears most pts immunologically respond to vaccine though slightly less for VR in most assays. The changes of Tregs appear to correlate best with disease recurrence. Whether this reflects an association with disease status or a failure of the vaccine is yet to be seen. These levels may become important in predicting risk for clinical recurrence in future vaccine trials.

Safety and long-term maintenance of anti-HER2 immunity following booster inoculations of the E75 breast cancer vaccine

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Background: We have completed accrual and are in the follow up portion of phase I/II clinical trials evaluating the E75 HER2 peptide vaccine. E75 has been proven safe, capable of stimulating HER2 immunity, and effective in decreasing breast cancer recurrence rates. During the conduct of this trial, it was noted that E75-specific immunity waned after the Primary Vaccine Series (PVS) which corresponded with late recurrences. To maintain long-term immunity, a voluntary booster program was started. Here we present analysis of the booster inoculations. Methods: The trial enrolled node-positive or high-risk, node-negative breast cancer patients (pts) with tumors expressing any level of HER2 (IHC 1-3+). HLA-A2/A3+ pts comprised the vaccine group (VG), HLA-A2/A3- pts were followed as the control group (CG). The VG received 4-6 monthly inoculations of E75+GM-CSF. Volunteer booster program pts (BG) received inoculations every 6 months after the PVS. Pts were monitored for toxicities, in vivo responses by local reactions (LR) and DTH, and in vitro responses measured by enumeration of E75 specific cytotoxic T lymphocytes. Results: 53 pts received at least 1 booster, 34 received 2, 24 three, 20 four, 12 five, and 8 at least 6. 24% of pts had no local toxicity, 73% Grade 1 (G1), 3% G2. 74% had no systemic toxicity, 35% G1, 1% G2. LRs increased significantly from the initial vaccine (R1) during PVS to each booster (B) (R1: 59.5±3.1 v B1: 89.2±3.3, p<0.001; v B2: 95.15±5, p<0.001; v B3: 86.63±5.5, p<0.001; v B4: 83.26±4.6, p=<0.001; v B5: 80.67±6.7, p=0.006; v B6: 78.75±9.4, p=0.04). Dimer values increased from the end of PVS to each post-booster value (pre B1:1.29±0.25 v post B1: 1.46±0.38; post B2: 1.41±0.4; post B3: 1.84±0.35; post B4: 2.23±0.4; post B5:1.94±0.31; post B6: 2.73±0.09, p=0.02). At median 60 months, the recurrence rate for BG was 3.8% vs 18.9% in the CG (p=0.01). Conclusions: Booster inoculations are well-tolerated and appear to assist in the maintenance of long term peptide-specific immunity. Boosted pts have improved recurrence rates. Based on the success of this program, we have incorporated the practice of booster inoculations in our current cancer vaccine trials.