Variation in the Incidence and Magnitude of Tumor-Infiltrating Lymphocytes in Breast Cancer Subtypes: A Systematic Review

Importance

The presence of tumor-infiltrating lymphocytes (TILs) is a favorable prognostic factor in breast cancer, and TILs may synergize with chemotherapy and immune checkpoint inhibitor therapy for improved clinical response. A more detailed understanding of the variation in lymphocytic infiltration in breast cancer may aid in identifying subtypes more amenable to immunomodulation.

Objective

To determine the median percentage of patients with breast cancer with no, intermediate, or high levels of TIL and assess variations in lymphocytic cell subsets across breast cancer subtypes.

Evidence Review

Eligible studies (PubMed, 1990-2015) analyzed tumor lymphocytic, CD8+, and FOXP3+ cellular infiltrates, and used multivariable analyses and quantitative methods for enumerating cell populations. Selection of of studies was performed in accordance with PRISMA guidelines and evaluated by 2 independent appraisers.

Findings

Fifteen studies (n = 13 914) met prespecified criteria and were reviewed in December 2015. A median of 11% (range, 5%-26%) of breast cancers demonstrate lymphocyte-predominant breast cancer (LPBC), with approximately 16% of cancers showing no evidence of TILs. Triple-negative (TN) breast cancers demonstrated the highest incidence of LPBC (20%; range, 4%-37%). This incidence is similar to that of breast cancers that are human epidermal growth factor 2 positive and either hormone receptor positive or negative (HER2+) at 16% (range 11%-24%). Hormone receptor positive/HER2- (HR+) breast cancer showed the lowest incidence of LPBC at 6% (range, 3%-12%). CD8+ T-cell infiltrates, indicative of type I immunity, were found in 48% of all breast cancers (range, 32%-80%) with similar levels observed in TN (60%; range, 40%-91%) and HER2+ disease (61%; range, 40%-83%). Fewer HR+ tumors demonstrated CD8+ TIL (43%; range, 30%-73%). The highest levels of FOXP3+ cells were observed in TN (70%; range, 65%-76%) and HER2+ disease (67%; range, 61%-74%). A minority of HR+ breast cancers demonstrated high levels of tumor-infiltrating FOXP3+ cells (38%; range, 35%-41%).

Conclusions and Relevance

The magnitude of TIL is variable within and between breast cancer subtypes. Levels of lymphocytic subpopulations may identify breast cancers more amenable to immunomodulation and indicate additional strategies to enhance immunity in patients with low to moderate levels of TILs.

Abstract OT3-01-03: A phase I trial of the safety and immunogenicity of a DNA plasmid based vaccine (WOKVAC) encoding epitopes derived from three breast cancer antigens (IGFBP2, HER2, and IGF1R) in patients with breast cancer

Background: Three proteins insulin like growth factor binding protein 2 (IGFBP2), human epidermal growth factor receptor 2 (HER2), and insulin like growth factor receptor-1 (IGF1R) are overexpressed in in pre-invasive and high risk breast lesions and are associated with progression to invasive breast cancer. These proteins are immunogenic and elicit both humoral and cellular immunity in breast cancer patients. It is hypothesized that immunization with a plasmid vaccine (WOKVAC) targeting antigens from these proteins will be safe and immunogenic. WOKVAC has been designed to include extended sequences of the immunizing antigens that are predominantly associated with eliciting Type I immune responses. Type I immunity results in immune cells called T-cells secreting high levels of inflammatory cytokines (called Th1) that stimulate tumor destruction as well as the generation of cytotoxic T-cells that can directly kill the tumors.

Trial design: Phase I dose escalation study of 3 doses of WOKVAC admixed with 100mcg of GM-CSF. Patients will be assigned sequentially to one of three arms (10 patients/arm): Arm 1=150mcg, Arm 2=300mcg, Arm 3=600mcg. Each dose arm will have a staggered enrollment to assess toxicity. If the Arm 1 dose is determined to be safe, Arm 2 patients can be enrolled. If the Arm 2 dose is safe and immunologically more efficacious than Arm 1 then Arm 3 patients can be enrolled. Study treatment includes 3 monthly vaccines, two evaluations at 1 and 6 months post vaccine and a 5 year follow-up to collect reports from the patient's primary oncologist. Toxicity is assessed at baseline through the end of the study. Serial blood draws for immunologic monitoring is done.

Eligibility criteria: Patients with non-metastatic, node positive, HER2 negative breast cancer that is in remission and defined as no evidence of disease. Patients must have a good performance status, be at least 28 days from last cytotoxic chemotherapy and/or radiotherapy and 28 days from any use of systemic steroids.

Specific aims: (1) Determine safety of 3 escalating doses of WOKVAC, (2) Determine the most immunogenic dose, (3) Determine whether a WOKVAC Th1 polyepitope plasmid based vaccine elicits a persistent memory T-cell and (4) Determine whether WOKVAC vaccination modulates T regulatory cells and myeloid derived suppressor cells.

Statistical methods: (1) Safety will be assessed per NCI CTCAE v. 4.0, (2) Immunogenicity will be defined by the magnitude of the Th1 IFN-gamma antigen specific immune response. Successful immunization is a protein specific IFN-g precursor frequency greater than 1:20,000 PBMC for each antigen or 2 fold increase if baseline immune response (3) The IGFBP2, HER2, and IGF1R specific IFN-g/IL-10 ratios by ELISPOT will be evaluated to determine that a predominantly Th1 immune response is stimulated, and (4) Humoral immune response will be measured by ELISA and serum antibody avidity for IGFBP2, HER2, and IGF1R to determine an avidity index (AI) before and after vaccination.

Targeted Accrual: 30 patients

Contact information:

University of Washington: 866-392-8588/TrialTVG@uw.edu

University of Wisconsin: 608-265-2493/prevention@uwcarbone.wisc.edu.

Citation Format: Childs JS, Higgins DM, DeShong K, Heckman-Stoddard BM, Wojtowicz ME, Stanton SE, Bailey HH, Wisinski KB, Disis ML. A phase I trial of the safety and immunogenicity of a DNA plasmid based vaccine (WOKVAC) encoding epitopes derived from three breast cancer antigens (IGFBP2, HER2, and IGF1R) in patients with breast cancer [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 OT3-01-03.

Immunization against HIF-1α Inhibits the Growth of Basal Mammary Tumors and Targets Mammary Stem Cells In Vivo

Purpose: Triple-negative breast cancer (TNBC) represents a cancer stem cell-enriched phenotype. Hypoxia-inducible factor-1α (HIF-1α) induces the expression of proteins associated with stemness and is highly upregulated in TNBC. We questioned whether HIF-1α was immunogenic and whether vaccination targeting HIF-1α would impact the growth of basal-like mammary tumors in transgenic mice.Experimental Design: We evaluated HIF-1α-specific IgG in sera from controls and patients with breast cancer. Class II epitopes derived from the HIF-1α protein sequence were validated by ELISPOT. To assess therapeutic efficacy, we immunized Tg-MMTVneu and C3(1)Tag mice with HIF-1α Th1-inducing peptides. Stem cells were isolated via magnetic bead separation. Levels of HIF-1α and stem cells in the tumor were quantitated by Western blotting and flow cytometry.Results: The magnitude (P < 0.001) and incidence (P < 0.001) of HIF-1α-specific IgG were elevated in TNBC patients compared with controls. Both breast cancer patients and donors showed evidence of HIF-1α-specific Th1 and Th2 immunity. Three HIF-1α-specific Th1 class II restricted epitopes that were highly homologous between species elicited type I immunity in mice. After HIF-1α vaccination, mammary tumor growth was significantly inhibited in only C3(1)Tag (basal-like/stem cell^high; P < 0.001) not TgMMTV-neu (luminal/neu/stem cell^low; P = 0.859) murine models. Vaccination increased type I T cells in the tumor (P = 0.001) and decreased cells expressing the stem cell marker, Sca-1, compared with controls (P = 0.004).Conclusions: An HIF-1α vaccine may be uniquely effective in limiting tumor growth in TNBC. Inhibiting outgrowth of breast cancer stem cells via active immunization in the adjuvant setting may impact disease recurrence. Clin Cancer Res; 23(13); 3396-404. ©2016 AACR.

The Human Vaccines Project: A roadmap for cancer vaccine development

Cancer vaccine development has been vigorously pursued for 40 years. Immunity to tumor antigens can be elicited by most vaccines tested, but their clinical efficacy remains modest. We argue that a concerted international effort is necessary to understand the human antitumor immune response and achieve clinically effective cancer vaccines.

Phase Ib Trial of the Toll-like Receptor 8 Agonist, Motolimod (VTX-2337), Combined with Cetuximab in Patients with Recurrent or Metastatic SCCHN

Purpose: As Toll-like receptors (TLR) are key mediators of immune responses, TLR agonists may be important for augmenting the efficacy of therapies for squamous cell carcinoma of the head and neck (SCCHN). Motolimod (VTX-2337), a selective small-molecule agonist of TLR8, stimulates natural killer (NK) cells, dendritic cells, and monocytes. A phase Ib clinical trial assessed the safety and antitumor activity of motolimod in combination with cetuximab in patients with SCCHN. Correlative biomarkers of immune activity were explored.Experimental Design: Thirteen patients with recurrent or metastatic SCCHN were enrolled in this open-label, dose-escalation study using a standard 3 + 3 design. Doses of motolimod (2.5, 3.0, or 3.5 mg/m²) were given on days 1, 8, and 15, in combination with fixed weekly doses of cetuximab in 28-day cycles.Results: There were no protocol-defined dose-limiting toxicities, drug-related deaths, or evidence of synergistic toxicities between motolimod and cetuximab. Clinical tolerability at the 3.5 mg/m² dose level was not optimal for repeated dosing and 3.0 mg/m² was identified as the MTD. Two patients achieved partial responses for an overall response rate of 15%. Five patients had disease stabilization equating to a disease control rate of 54%. Statistically significant increases in plasma cytokines and in the frequency and activation of circulating NK cells were observed.Conclusions: Motolimod can be safely administered in combination with cetuximab with an acceptable toxicity profile. Encouraging antitumor activity and robust pharmacodynamic responses were observed. Motolimod is being further investigated in a phase II trial in patients with SCCHN (ClinicalTrials.gov ID: NCT01836029). Clin Cancer Res; 23(10); 2442-50. ©2016 AACR.

Epidermal growth factor receptor derived peptide vaccination to prevent lung adenocarcinoma formation: An in vivo study in a murine model of EGFR mutant lung cancer

The ability to prevent disease is the holy grail of medicine. For decades, efforts have been made to extend the successes seen with vaccination against infectious diseases to cancer. In some instances, preventive vaccination against viruses (prototypically HPV) has successfully prevented tumorigenesis and will make a major impact on public health in the decades to come. However, the majority of cancers that arise are a result of genetic mutation within the host, or non-viral environmental exposures. We present compelling evidence that vaccination against an overexpressed self-tumor oncoprotein has the potential to prevent tumor development. Vaccination against the Epidermal Growth Factor Receptor (EGFR) using a multipeptide vaccine in a preventive setting decreased EGFR-driven lung carcinogenesis by 76.4% in a mouse model of EGFR-driven lung cancer. We also demonstrate that anti-EGFR vaccination primes the development of a robust immune response in vivo. This study provides proof of concept for the first time that targeting tumor drivers in a preventive setting in lung cancer using peptide vaccination can inhibit tumorigenesis and may provide useful clinical insights into the development of strategies to vaccinate against EGFR in populations where EGFR-mutant disease is highly prevalent. © 2015 Wiley Periodicals, Inc.

Clinical significance of tumor-infiltrating lymphocytes in breast cancer

Tumor infiltrating lymphocytes (TIL) play an essential role in mediating response to chemotherapy and improving clinical outcomes in all subtypes of breast cancer. Triple negative breast cancers (TN) are most likely to have tumors with >50 % lymphocytic infiltrate, termed lymphocyte predominant breast cancer, and derive the greatest survival benefit from each 10 % increase in TIL. The majority of HER2+ breast cancers have similar level of immune infiltrate as TN breast cancer yet the presence of TILs has not shown the same survival benefit. For HER2+ breast cancers, type 1 T-cells, either increased TBET+ tumor infiltration or increased type 1 HER2-specific CD4+ T-cells in the peripheral blood, are associated with better outcomes. Hormone receptor positive HER2 negative tumors tend to have the least immune infiltrate yet are the only breast cancer subtype to show worse prognosis with increased FOXP3 regulatory T-cell infiltrate. Notably, all breast cancer subtypes have tumors with low, intermediate, or high TIL infiltrate. Tumors with high TILs may also have increased PD-L1 expression which might be the reason that TN breast cancer seems to demonstrate the most robust clinical response to immune checkpoint inhibitor therapy but further investigation is needed. Tumors with intermediate or low levels of pre-treatment immune infiltrate, on the other hand, may benefit from an intervention that may increase TIL, particularly type 1 T-cells. Examples of these interventions include specific types of cytotoxic chemotherapy, radiation, or vaccine therapy. Therefore, the systematic evaluation of TIL and specific populations of TIL may be able to both guide prognosis and the appropriate sequencing of therapies in breast cancer.

Concurrent SPECT/PET-CT imaging as a method for tracking adoptively transferred T-cells in vivo

Background

The ability of T-cells to traffic to and penetrate tumors impacts the clinical efficacy of T-cell therapy therefore methods to track transferred T-cells in vivo are needed. In this preliminary report, we evaluated the use of concurrent SPECT/PET-CT imaging to monitor the egress of HER-2/neu specific T-cells in a breast cancer patient with extensive bone-only metastatic disease.

Findings

Indium (In-111) labeled T-cells demonstrated similar or greater viability than unlabeled T-cells at either a low or high dose of In-111 over a 24-h incubation period in vitro. The function of labeled or unlabeled T-cells was not significantly different (p > 0.05) at either dose. T-cells trafficked to all sites of metastatic disease and infiltrated the tumor as assessed by SPECT imaging. In-111 uptake at 24 h after infusion varied from 3.8 (right proximal humerus) to 6.3 (right sacrum) background corrected counts per pixel and remained elevated at 48 h. Concurrent PET-CT imaging demonstrated a fluorodeoxyglucose flare, measured by increase in tumor site uptake as high as 32 % and at most sites of disease at 48 h. This flare was associated with focal pain after T-cell infusion at metastatic sites. The patient had stable disease for 18 months after completion of T-cell therapy.

Conclusion

Concurrent SPECT/PET-CT imaging, over a 48-h period after T-cell infusion, provided evidence of T-cell homing to all disease sites as well as a tumor metabolism flare response. This technique may be useful for monitoring T-cell trafficking after autologous as well as chimeric antigen receptor T-cell infusion.

Trial Registraion

Trial registered at ClinicalTrials.gov registration number NCT00791037, registered 13 November 2008.

CITN11-02 phase I trial of subcutaneous recombinant human IL-15 (rhIL-15) is associated with expansion of circulating CD56+ NK cells and CD8+ T cells

Background

IL-15 is a high priority for clinical development because of its homeostatic effects on both NK cells and CD8+ T cells, and minimal effect on regulatory T cells. The Cancer Immunotherapy Trials Network is conducting a phase I dose-escalation study of subcutaneous (SQ) rhIL-15 in advanced melanoma, renal cell, non-small cell lung and squamous cell head and neck carcinoma patients.

Methods

A cycle consists of 5 daily SQ injections of rhIL-15 (E.coli-derived, NCI) given Monday-Friday for two weeks, then 2 weeks observation. The absolute lymphocyte count is tested every injection day, and whole blood flow cytometric analyses are conducted on Days 1, 11 and 15 of each cycle.

Results

Three patients each were treated at the 0.25, 0.5, 1.0 and 3.0 mcg/kg dose levels and six patients at 2.0 mcg/kg/dose (N=18). Seventeen patients completed ≥1 cycle, with one dose limiting toxicity (DLT) at 3.0 mcg/kg and one serious adverse event at 2.0 mcg/kg. Flow cytometric data indicate a consistent increase in the frequency of CD56+CD3− NK cell frequencies peaking at Day 15 of Cycle 1 (Day 12=last dose), with lesser increases in subsequent cycles. The median fold-increase in circulating NK cells during Cycle 1 demonstrated dose responsiveness and peaked at 11.5-fold with 3.0 mcg/kg. By contrast, the maximum fold-increase in circulating CD8+ T cells was 2.6-fold.

Conclusion

SQ rhIL-15 has been well tolerated and the 3.0 mcg/kg dose cohort is being expanded. Higher doses of rhIL-15 were associated with profound increases in circulating NK cells with significant but smaller increases in CD8+ T cells. Outpatient use of SQ rhIL-15 is safe and will be combined with other cancer immunotherapies.

Study support: NIH 1U01 CA154967-01 (Clinical Trials.gov NCT01727076).

Immunodynamics: a cancer immunotherapy trials network review of immune monitoring in immuno-oncology clinical trials

The efficacy of PD-1/PD-L1 targeted therapies in addition to anti-CTLA-4 solidifies immunotherapy as a modality to add to the anticancer arsenal. Despite raising the bar of clinical efficacy, immunologically targeted agents raise new challenges to conventional drug development paradigms by highlighting the limited relevance of assessing standard pharmacokinetics (PK) and pharmacodynamics (PD). Specifically, systemic and intratumoral immune effects have not consistently correlated with standard relationships between systemic dose, toxicity, and efficacy for cytotoxic therapies. Hence, PK and PD paradigms remain inadequate to guide the selection of doses and schedules, both starting and recommended Phase 2 for immunotherapies. The promise of harnessing the immune response against cancer must also be considered in light of unique and potentially serious toxicities. Refining immune endpoints to better inform clinical trial design represents a high priority challenge. The Cancer Immunotherapy Trials Network investigators review the immunodynamic effects of specific classes of immunotherapeutic agents to focus immune assessment modalities and sites, both systemic and importantly intratumoral, which are critical to the success of the rapidly growing field of immuno-oncology.

Coordinated Activation of Toll-Like Receptor8 (TLR8) and NLRP3 by the TLR8 Agonist, VTX-2337, Ignites Tumoricidal Natural Killer Cell Activity

VTX-2337 (USAN: motolimod) is a selective toll-like receptor 8 (TLR8) agonist, which is in clinical development as an immunotherapy for multiple oncology indications, including squamous cell carcinoma of the head and neck (SCCHN). Activation of TLR8 enhances natural killer cell activation, increases antibody-dependent cell-mediated cytotoxicity, and induces Th1 polarizing cytokines. Here, we show that VTX-2337 stimulates the release of mature IL-1β and IL-18 from monocytic cells through coordinated actions on both TLR8 and the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome complex. In vitro, VTX-2337 primed monocytic cells to produce pro-IL-1β, pro-IL-18, and caspase-1, and also activated the NLRP3 inflammasome, thereby mediating the release of mature IL-1β family cytokines. Inhibition of caspase-1 blocked VTX-2337-mediated NLRP3 inflammasome activation, but had little impact on production of other TLR8-induced mediators such as TNFα. IL-18 activated natural killer cells and complemented other stimulatory pathways, including FcγRIII and NKG2D, resulting in IFNγ production and expression of CD107a. NLRP3 activation in vivo was confirmed by a dose-related increase in plasma IL-1β and IL-18 levels in cynomolgus monkeys administered VTX-2337. These results are highly relevant to clinical studies of combination VTX-2337/cetuximab treatment. Cetuximab, a clinically approved, epidermal growth factor receptor-specific monoclonal antibody, activates NK cells through interactions with FcγRIII and facilitates ADCC of tumor cells. Our preliminary findings from a Phase I open-label, dose-escalation, trial that enrolled 13 patients with recurrent or metastatic SCCHN show that patient NK cells become more responsive to stimulation by NKG2D or FcγRIII following VTX-2337 treatment. Together, these results indicate that TLR8 stimulation and inflammasome activation by VTX-2337 can complement FcγRIII engagement and may augment clinical responses in SCCHN patients treated with cetuximab.

Trial Registration: ClinicalTrials.gov NCT01334177

Abstract PD3-08: Modulation of immunity with 2-fluorofucose (2FF) for breast cancer treatment and prevention

The majority of patients with breast cancer have robust Type II immune responses directed against their tumors with little to no Type I immunity. The dominance of a Type II microenvironment is established early in breast tumorigenesis with a Type II immune signature prevalent even in pre-invasive lesions such as ductal carcinoma in situ. As a result, breast cancer is associated with abundant autoantibodies directed against tumor associated antigens and few infiltrating T-cells in the majority of patients. A recently reported inhibitor of protein and cellular fucosylation, 2-fluorofucose (2FF) has been shown to enhance immune cell function, in part through the generation of fucose-deficient antibodies which result in enhanced antibody dependent cell mediated cytotoxicity, as well as apparent modulation of T-cell dependent activity [Ca Res, Oct 1, 2014 74;2890].

For treatment studies, TgMMTV-neu (MMTVneu; luminal) and C31-Tag (C3T; triple negative) mice were treated orally with vehicle alone and 20mM 2FF when spontaneous tumor volume reached 75-100mm3 until sacrifice (n=20/grp). To assess the ability to prevent breast cancer development, mice were treated orally with vehicle alone, 20 or 50mM 2FF for up to 200 days starting at 6-8 weeks of age (n=20/grp). Tumor kinetics, disease free survival, and overall survival were calculated. Immune responses were evaluated by both DTH and IFN-gamma ELISPOT. To determine immune mechanism of action, NK, B, CD4, or CD8 cells were depleted concurrently with tumor implant.

When tumor bearing mice were treated with 2FF, tumor growth was significantly inhibited in both groups over the course of therapy (MMTVneu p&lt;0.0001 and C3T p&lt;0.0001 compared to controls). In addition, survival was significantly prolonged in both models (MMTVneu p&lt;0.0001 and C3T p=0.0014). In the prevention setting, 2FF significantly delayed the average age of tumor onset in both models at both doses with the higher does showing greater efficacy; MMTVneu 20mM, p=0.001, 50mM, p=0.0002. At the time of study termination (300d), 45% of 2FF-treated MMTVneu mice had no evidence of mammary tumors. 2FF also significantly improved the average age of tumor onset in C3T mice when comparing untreated to 20mM (p=0.007), and 50mM (p=0.0007) treated mice. At study termination, 33% of all 2FF-treated C3T animals were disease free. 2FF anti-tumor activity was associated with the induction of tumor antigen specific immunity. After treatment both the MMTVneu (p&lt;0.0001) and C3T (p&lt;0.0001) developed a DTH response to syngeneic tumor lysates. Of note, the DTH response was inversely associated with the rate of tumor growth (p&lt;0.0001). 2FF anti-tumor activity was associated with the induction of tumor antigen specific immunity. Depletion of immune cell subsets using targeting antibodies demonstrated that the anti-tumor response was mediated in large part by CD4 T-cells which are involved in stimulating both humoral and CD8 T-cell responses.

2FF, a novel inhibitor of fucosylation has potent anti-tumor effects in 2 transgenic models of breast cancer; luminal and triple negative mammary tumors. The agent is active in these mouse models in both the treatment and prevention setting and thus may represent a rational therapeutic approach to evaluate in breast cancer patients.

Citation Format: Disis ML, Rastetter L, Gad E, Koehnlein M, Senter PD, Gardai S, Okeley NM. Modulation of immunity with 2-fluorofucose (2FF) for breast cancer treatment and prevention. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD3-08.

Triple-negative breast cancer: immune modulation as the new treatment paradigm

Recent studies of tumor lymphocytic immune infiltrates in breast cancer have suggested an improved prognosis associated with increasing levels of tumor-infiltrating lymphocytes (TIL). Triple-negative breast cancer (TNBC) is the breast cancer subtype that has the greatest incidence of patients with a robust tumor immune infiltrate, although it is still a minority of patients. Elevated levels of either intratumoral or stromal T cells are associated with an improved overall survival (OS) and disease-free survival (DFS) in TNBC as compared with other breast cancer subtypes. TNBC may be immunogenic for several reasons. Subtypes of TNBC have a significant number of genetic mutations, and the immune system may see the aberrant proteins encoded by these mutations as foreign. Moreover, TNBC is associated with a prognostic gene signature that also includes B cells. Antibodies secreted by B cells may bind to tumor antigens and amplify the adaptive immune response that has already been initiated in the tumor. New immune modulatory agents, including immune checkpoint inhibitors, have shown activity in immunogenic tumors such as melanoma and bladder cancer and have recently been tested in TNBC. The clinical response rates observed, patterns of response, and adverse event profiles are similar to what has been described in melanoma where this class of agents has already been approved for clinical use in some cases. Lessons learned in assessing the immunogenicity of TNBC, potential mechanisms of immune stimulation, and response to immune modulatory drugs lay the foundation for the development of immune-based therapies in all subtypes of the disease.

Abstract P2-11-05: Overall survival in inflammatory breast cancer patients receiving Her-2 Neu directed tumor vaccine therapy: Matched comparison with SEER registry patients

Background

Patients with inflammatory breast cancer (IBC) have a poor prognosis, primarily due to distant dissemination. Additionally, IBC patients have an increased rate of HER2 overexpression when compared to patients with non-inflammatory breast cancer. The forms the rationale for HER2 directed tumor vaccine therapy in these patients. The purpose of this study was to examine overall survival in IBC patients receiving HER2 directed tumor vaccine therapy when compared with matched control patients from the SEER Registry.

Methods

Patients with diagnosis of Stage III or IV HER2 positive IBC having completed standard initial therapy and without evidence of disease received HER2 vaccinations after being enrolled on 5 prospective clinical trials. Overall survival data were pooled and analyzed. A control group of matched IBC patients were identified by querying the SEER database from 1997-2011. The control group was identified as any individual in the database with a code for IBC. A secondary analysis comparing survival in HER2 positive IBC vs HER2 negative IBC patients was performed by querying the SEER database from 2010 onwards, the time point when the HER2 status was coded in the database. Propensity score adjustment were made to the control group to account for any imbalances between groups in measured covariates such as stage, race, age, sex, and era of enrollment and the time interval from diagnosis to enrollment on vaccine trial (median ∼2 years).

Results

A total of 37 IBC patients received HER2 directed vaccine therapy and 676 patients were identified for the SEER control group; Stage at enrollment: stage IIIB: 30 patients in the vaccine group and 639 patients in the control group; stage IIIC: 1 patient in the vaccine group and 15 patients in the control group; stage IV 6 patients in the vaccine group and 22 in the control group. The median survival of the overall population was 112 months for the vaccine group and 47 months for the control group (p=0.04). After using propensity scores to adjust the control for imbalances in measured covariates, the median survival for the overall population was 112 months for the vaccine group and 37 months for the control group (p=0.03). There was no difference in survival between HER2 positive and HER2 negative IBC patients in the control group (p=0.6).

Conclusion

These results demonstrate promising overall survival in HER2 positive IBC patients receiving HER2 directed vaccine therapy after initial therapy. Propensity matching was performed to adjust for imbalances in measured covariates and resulted in a modest decrease in survival of the control group after adjustment, suggesting that the vaccine trial group had relatively unfavorable pre-treatment characteristics. Despite these unfavorable characteristics, patients receiving vaccine had a median survival of 112 months. These results must be further confirmed in a prospective randomized trial.

Citation Format: Rengan R, Baker K, Salazar L, Childs J, Higgins D, Redman M, Reichow J, Disis ML. Overall survival in inflammatory breast cancer patients receiving Her-2 Neu directed tumor vaccine therapy: Matched comparison with SEER registry patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-11-05.

The Antitumor Efficacy of IL2/IL21-Cultured Polyfunctional Neu-Specific T Cells Is TNFα/IL17 Dependent

PURPOSE

Infusion of HER2-specific T cells, derived from vaccine-primed patients and expanded with IL2/IL12, has induced tumor regression in a minority of patients with metastatic treatment-refractory HER2(+) breast cancer. We questioned whether alteration of cytokine growth factors used to culture vaccine-primed T cells could improve antitumor activity.

EXPERIMENTAL DESIGN

Using the TgMMTV-neu murine mammary tumor model, we cultured T cells derived from mice immunized with a previously defined neu class II peptide, p98-114 (neu p98), and evaluated different cytokine combinations for expansion.

RESULTS

Infusion of neu p98-specific T-cell lines derived from all cytokine conditions evaluated resulted in significant antitumor activity compared with infused naïve splenocytes (P < 0.05). T cells cultured with IL2/IL21 could uniquely mediate complete regression of spontaneous mammary tumors. IL2/IL21 cultured neu-specific T cells demonstrated a different cytokine secretion pattern as compared with other cultured T cells; secreting high levels of TNFα and IL17 (P < 0.05). Moreover, tumor-infiltrating CD8(+) cells were significantly increased after the infusion of IL2/IL21 cultured T cells as compared with tumors treated with T cells expanded under other cytokine conditions (P < 0.001). The antitumor effect of the infusion of IL2/IL21 cultured cells was mediated by CD8 T cells. Depletion of TNFα or IL17, but not IFNγ, abrogated the tumor growth inhibition induced by the IL2/IL21 T cells and markedly decreased the influx of CD8 into tumors. Finally, IL2/IL21-cultured human antigen specific T cells also displayed a similar polyfunctional Th1/Th17 phenotype.

CONCLUSIONS

Expansion of HER2 vaccine-primed T cells with IL2/IL21 may have the potential to effectively mediate tumor regression when used in adoptive transfer. Clin Cancer Res; 22(9); 2207-16. ©2015 AACR.