Long-term complete remission following radiosurgery and immunotherapy in a melanoma patient with brain metastasis: immunologic correlates

A melanoma patient with brain metastases was treated by gamma-knife radiosurgery and immunotherapy with autologous tumor-lysate-loaded dendritic cells (DC). Ten years after the combined treatment, the patient remains in complete remission. Remarkable immunologic correlates to the clinical development were the transient induction of NY-ESO-1 antibody and the durable expansion of MAGE-A1p161-169 EADPTGHSY-specific CD8+ T cells. Although the induction of NY-ESO-1 antibody most likely resulted from gamma-knife-mediated "auto-vaccination," the persistence of circulating MAGE-A1-specific T cells, which are still detectable ex vivo in the absence of any tumor manifestation, coincides with DC-based vaccination administered monthly until today.

Plasticity in the contribution of T cell receptor variable region residues to binding of peptide-HLA-A2 complexes

One hypothesis accounting for major histocompatibility complex (MHC) restriction by T cell receptors (TCRs) holds that there are several evolutionary conserved residues in TCR variable regions that contact MHC. While this "germline codon" hypothesis is supported by various lines of evidence, it has been difficult to test. The difficulty stems in part from the fact that TCRs exhibit low affinities for pep/MHC, thus limiting the range of binding energies that can be assigned to these key interactions using mutational analyses. To measure the magnitude of binding energies involved, here we used high-affinity TCRs engineered by mutagenesis of CDR3. The TCRs included a high-affinity, MART-1/HLA-A2-specific single-chain TCR and two other high-affinity TCRs that all contain the same Vα region and recognize the same MHC allele (HLA-A2), with different peptides and Vβ regions. Mutational analysis of residues in CDR1 and CDR2 of the three Vα2 regions showed the importance of the key germline codon residue Y51. However, two other proposed key residues showed significant differences among the TCRs in their relative contributions to binding. With the use of single-position, yeast-display libraries in two of the key residues, MART-1/HLA-A2 selections also revealed strong preferences for wild-type germline codon residues, but several alternative residues could also accommodate binding and, hence, MHC restriction. Thus, although a single residue (Y51) could account for a proportion of the energy associated with positive selection (i.e., MHC restriction), there is significant plasticity in requirements for particular side chains in CDR1 and CDR2 and in their relative binding contributions among different TCRs.

Final results of the AIO 0307 study: A controlled, randomized, double-blind phase II study of FOLFOX6 or FOLFIRI combined with sorafenib (S) versus placebo (P) in second-line metastatic colorectal carcinoma (mCRC) treatment

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Background: The oral multikinase inhibitor Sorafenib (S) inhibits angiogenesis and tumor growth in preclinical models of CRC. This study investigated the addition of S to standard 2nd line chemotherapy (CTX). Methods: Patients (pts) with mCRC and progression after first-line therapy with an oxaliplatin- or irinotecan based fluoropyrimidine containing regimen ± Bevacizumab (Bev), were randomized to receive chemotherapy (CTX) (FOLFOX6 or FOLFIRI) + S (400 mg bid) or CTX + placebo (P). 240 pts were planned to be enrolled to ensure a power of 80% if median progression-free survival (PFS) with S is increased by 2 months compared to P. Results: Between 04/09 and 10/11, 101 pts were enrolled. Recruitment was stopped prematurely due to slow accrual. 97 pts were evaluable in the full analysis set. Median age was 65 years, 60 pts were male, 97% with ECOG 0 or 1. Median PFS was 5.2 months (mths) in S and 5.6 mths in P (HR 0.84, 90% CI 0.58, 1.22, p=0.439). Best response rate was 25.6% and 12.2% (p=0.106), respectively. Disease control rates were comparable. Median overall survival (OS) was 9.6 mths with S compared to 12.7 mths with P (HR 1.57, 90% CI 1.03, 2.41, p = 0.076). Difference in OS was even more pronounced in subgroup (n=41) with FOLFOX6 backbone (9.6 vs. 13.8 mths, HR 2.37, 90% CI 1.22, 4.60, p=0.026). In 69 Bev-pretreated pts OS was 8.4 vs. 14.9 mths (HR 2.30; 90% CI 1.36, 3.88, p=0.007) compared to 13.1 vs. 7.4 mths (HR=0.61; 90% CI 0.28, 1.36, p=0.308) in 28 pts without Bev pretreatment. Adverse events (AEs) were consistent with the known safety profiles. Most frequent grade 3/4 AEs affected the gastrointestinal tract (diarrhea, mucositis/stomatitis, nausea); other frequent severe AEs included neutropenia and leukopenia, fatigue, fever, sensory neuropathy, and thrombosis. Conclusions: No unexpected safety concerns occurred during the course of the study. S did not lead to improved PFS. There was a detrimental effect of S on OS in patients with Bev pretreatment. Clinical trial information: 2008-000803-26.

HLA Class II tetramers reveal tissue-specific regulatory T cells that suppress T-cell responses in breast carcinoma patients

Regulatory T cells (Tregs) play an important role in controlling antitumor T-cell responses and hence represent a considerable obstacle for cancer immunotherapy. The abundance of specific Treg populations in cancer patients has been poorly analyzed so far. Here, we demonstrate that in breast cancer patients, Tregs often control spontaneous effector memory T-cell responses against mammaglobin, a common breast tissue-associated antigen that is overexpressed by breast carcinoma. Using functional assays, we identified a HLA-DRB1*04:01- and HLA-DRB1*07:01-restricted epitope of mammaglobin (mam_34–48) that was frequently recognized by Tregs isolated from breast cancer patients. Using mam_34–48-labeled HLA Class II tetramers, we quantified mammaglobin-specific Tregs and CD4⁺ conventional T (Tcon) cells in breast carcinoma patients as well as in healthy individuals. Both mammaglobin-specific Tregs and Tcon cells were expanded in breast cancer patients, each constituting approximately 0.2% of their respective cell subpopulations. Conversely, mammaglobin-specific Tregs and CD4⁺ Tcon cells were rare in healthy individuals (0.07%). Thus, we provide here for the first time evidence supporting the expansion of breast tissue-specific Tregs and CD4⁺ Tcon cells in breast cancer patients. In addition, we substantiate the potential implications of breast tissue-specific Tregs in the suppression of antitumor immune responses in breast cancer patients. The HLA Class II tetramers used in this study may constitute a valuable tool to elucidate the role of antigen-specific Tregs in breast cancer immunity and to monitor breast cancer-specific CD4⁺ T cells.

A randomised multicentre phase II study with cisplatin/docetaxel vs oxaliplatin/docetaxel as first-line therapy in patients with advanced or metastatic non-small cell lung cancer

Background:

This study was designed to compare cisplatin/docetaxel with oxaliplatin/docetaxel in patients with advanced and metastatic non-small lung cancer as a first-line treatment.

Methods:

Patients were randomly assigned to receive either cisplatin 75 mg m⁻² and docetaxel 75 mg m⁻² every 3 weeks or oxaliplatin 85 mg m⁻² and docetaxel 50 mg m⁻² every 2 weeks. The primary end point was response rate, and secondary end points were toxicity, time to progression and overall survival.

Results:

A total of 88 patients (median age: 65 (39–86) years; stage IV: 93%) were randomly assigned. Response rate (complete and partial response) was 47% (95% CI: 33–61%) in the cisplatin/docetaxel arm and 28% (95% CI: 17–43%) in the oxaliplatin/docetaxel arm (P=0.118). There was no significant difference in time to progression (6.3 vs 4.9 months, P=0.111) and median overall survival (11.6 vs 7.0 months, P=0.102) with cisplatin/docetaxel vs oxaliplatin/docetaxel, although slight trends favouring cisplatin were seen. Oxaliplatin/docetaxel was associated with significantly less (any grade) renal toxicity (56% vs 11%), any grade fatigue (81% vs 59%), complete alopecia (76% vs 27%), any grade leukopenia (84% vs 61%) and grade 3/4 leukopenia (44% vs 14%) and neutropenia (56% vs 27%).

Conclusion:

Oxaliplatin/docetaxel has activity in metastatic non-small cell lung cancer, but it seems to be inferior to cisplatin/docetaxel.

NY-ESO-1 antigen-reactive T cell receptors exhibit diverse therapeutic capability

The cancer-testis antigen NY-ESO-1 has been used as a target for different immunotherapies like vaccinations and adoptive transfer of antigen-specific cytotoxic T cells, as it is expressed in various tumor types and has limited expression in normal cells. The in vitro generation of T cells with defined antigen specificity by T cell receptor (TCR) gene transfer is an established method to create cells for immunotherapy. However, an extensive characterization of TCR which are candidates for treatment of patients is crucial for successful therapies. The TCR has to be efficiently expressed, their affinity to the desired antigen should be high enough to recognize low amounts of endogenously processed peptides on tumor cells, and the TCR should not be cross-reactive to other antigens. We characterized three NY-ESO-1 antigen-reactive cytotoxic T lymphocyte clones which were generated by different approaches of T cell priming (autologous, allogeneic), and transferred their TCR into donor T cells for more extensive evaluations. Although one TCR most efficiently bound MHC-multimers loaded with NY-ESO-1 peptide, T cells expressing this transgenic TCR were not able to recognize endogenously processed antigen. A second TCR recognized HLA-A2 independent of the bound peptide beside its much stronger recognition of NY-ESO-1 bound to HLA-A2. A third TCR displayed an intermediate but peptide-specific performance in all functional assays and, therefore, is the most promising candidate TCR for further clinical development. Our data indicate that multiple parameters of TCR gene-modified T cells have to be evaluated to identify an optimal TCR candidate for adoptive therapy.

The efficiency of human cytomegalovirus pp65(495-503) CD8+ T cell epitope generation is determined by the balanced activities of cytosolic and endoplasmic reticulum-resident peptidases

Control of human CMV (HCMV) infection depends on the cytotoxic activity of CD8(+) CTLs. The HCMV phosphoprotein (pp)65 is a major CTL target Ag and pp65(495-503) is an immunodominant CTL epitope in infected HLA-A*0201 individuals. As immunodominance is strongly determined by the surface abundance of the specific epitope, we asked for the components of the cellular Ag processing machinery determining the efficacy of pp65(495-503) generation, in particular, for the proteasome, cytosolic peptidases, and endoplasmic reticulum (ER)-resident peptidases. In vitro Ag processing experiments revealed that standard proteasomes and immunoproteasomes generate the minimal 9-mer peptide epitope as well as N-terminal elongated epitope precursors of different lengths. These peptides are largely degraded by the cytosolic peptidases leucine aminopeptidase and tripeptidyl peptidase II, as evidenced by increased pp65(495-503) epitope presentation after leucine aminopeptidase and tripeptidyl peptidase II knockdown. Additionally, with prolyl oligopeptidase and aminopeptidase B we identified two new Ag processing machinery components, which by destroying the pp65(495-503) epitope limit the availability of the specific peptide pool. In contrast to cytosolic peptidases, silencing of ER aminopeptidases 1 and 2 strongly impaired pp65(495-503)-specific T cell activation, indicating the importance of ER aminopeptidases in pp65(495-503) generation. Thus, cytosolic peptidases primarily interfere with the generation of the pp65(495-503) epitope, whereas ER-resident aminopeptidases enhance such generation. As a consequence, our experiments reveal that the combination of cytosolic and ER-resident peptidase activities strongly shape the pool of specific antigenic peptides and thus modulate MHC class I epitope presentation efficiency.

Messenger RNA vaccination and B-cell responses in NSCLC patients

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Background: Vaccination with mRNA is a novel technology in cancer immunotherapy. CV9201 consists of self-adjuvanted mRNA molecules (RNActive) coding for five non small cell lung cancer (NSCLC)-associated tumor antigens (MAGE-C1, MAGE-C2, NY-ESO-1, BIRC5, 5T4). We report final results of a phase I/IIa trial of CV9201 in patients (pts.) with NSCLC. Methods: Pts. with stage IIIB/IV NSCLC with a response or stable disease after first-line chemotherapy or chemoradiation were eligible. Cohorts of 3 pts. were treated at three dose levels (400µg, 800µg and 1600µg CV9201) and observed for DLTs to select the highest tolerated dose for phase IIa. Primary endpoint was safety and tolerability; secondary endpoints were immune response, clinical efficacy and survival. Pts. received up to five vaccinations of CV9201 within 15 weeks. Antigen-specific immune responses against each of the 5 antigens were measured at baseline, and two weeks after the 3rd and 5th vaccination. Frequency of lymphocyte subsets and expression of activation and maturation markers were measured and retrospectively correlated with immunological and clinical parameters. Results: 46 pts. were included (9 phase I; 37 phase IIa); No DLTs occurred, and the 1600 µg dose was investigated in phase IIa. The most frequent related adverse events were mild to moderate injection site reactions and flu-like symptoms. 3 patients (7%) had potentially related grade 3 AEs (fatigue, injection site granuloma, asthma attack) and no related SAEs were reported. There were no objective responses. Data on PFS and survival will be presented. Antigen specific immune responses against at least one antigen were induced in 65% of pts. (39% cellular and 49% humoral). Consistently, a significant ≥2 fold increase of pre germinal center B cells (pGCB) was observed in 61% of pts. This increase of pGCB correlated significantly (p=0.0028) with increase of total CD4 effector T cells. Frequency of CD 4 T Reg cells did not increase during treatment. Conclusions: Vaccination with CV9201 has a favorable safety profile and induces T and B cell responses against all included antigens. Vaccine-induced increase of pGCB is a new finding and might be used as a biomarker in cancer immunotherapy.

[A composite osteomusculocutaneous free flap from the medial femoral condyle: anatomic characteristics, clinical aspects, new applications]

Advances in plastic and reconstructive surgery allow an almost complete functional and aesthetic reconstruction after severe injuries. However, particularly the treatment of complex defects involving different tissue components is still challenging. The reconstruction requires a combined flap consisting of different tissues from an adequate donor area. In this context, we focused on anatomical and clinical aspects of transplants from the area of the medial femoral condyle. In this study, the anatomical characteristics and potentials of various flaps from the region of this region are described. Moreover, previous literature on this subject is put in context with both the results of our own anatomical study and our clinical experience. The supplying vessel is the descending genicular artery with its branches. In addition to the consistency in vessel length and diameter, the descending genicular artery has a continuous distribution in a periosteal, cutaneous and muscular branch. Due to this anatomical characteristic, this donor site offers the possibility for several customized transplants. Thus, the distal medial thigh is a versatile and reliable donor site for plastic surgical procedures.

PD-1 expression on Melan-A-reactive T cells increases during progression to metastatic disease

Programmed death 1 (PD-1) is known as an important factor for the development of tolerogenicity. This has been proven in chronic viral infections and different tumor models. To address the role of PD-1 and its ligand programmed death ligand 1 (PD-L1) in different stages of malignant melanoma, we investigated peripheral blood and tumor tissues in regard to overall survival (OS) and prognostic relevance. One hundred samples of peripheral blood mononuclear cells from HLA-A2(+) patients with malignant melanoma (Stages I-IV) were analyzed in seven color FACS combined with multimer analyses for the immunodominant epitope of Melan-A (peptide A2/Melan-A(p26-35mod) ). Corresponding formalin-fixed paraffin-embedded tissues of primary tumor and distant organ metastases from 37 cases were analyzed by immunohistochemistry for Melan-A, PD-L1 and PD-1 expression. Compared to the total CD8(+) T cell population, PD-1 expression by A2/Melan-A(+) CD8(+) T cells was over-represented in melanoma stages III and IV (p < 0.001). Although elevation of PD-1(+) Melan-A(+) CD8(+) T cells had no significant influence on OS, a positive correlation was observed between PD-L1 expression on melanoma cells and OS (p = 0.05). Correlation of advanced tumor stage with increased A2/Melan-A-multimer(+) PD-1(+) T cells in the peripheral blood suggest that blocking of PD-1 could have therapeutic potential in advanced stage melanoma.

FLT3-regulated antigens as targets for leukemia-reactive cytotoxic T lymphocytes

The FMS-like tyrosine kinase 3 (FLT3) is highly expressed in acute myeloid leukemia (AML). Internal tandem duplications (ITD) of the juxtamembrane domain lead to the constitutive activation of the FLT3 kinase inducing the activation of multiple genes, which may result in the expression of leukemia-associated antigens (LAAs). We analyzed the regulation of LAA in FLT3-wild-type (WT)- and FLT3-ITD⁺ myeloid cells to identify potential targets for antigen-specific immunotherapy for AML patients. Antigens, such as PR-3, RHAMM, Survivin, WT-1 and PRAME, were upregulated by constitutively active FLT3-ITD as well as FLT3-WT activated by FLT3 ligand (FL). Cytotoxic T-cell (CTL) clones against PR-3, RHAMM, Survivin and an AML-directed CTL clone recognized AML cell lines and primary AML blasts expressing FLT3-ITD, as well as FLT3-WT⁺ myeloid dendritic cells in the presence of FL. Downregulation of FLT3 led to the abolishment of CTL recognition. Comparing our findings concerning LAA upregulation by the FLT3 kinase with those already made for the Bcr-Abl kinase, we found analogies in the LAA expression pattern. Antigens upregulated by both FLT3 and Bcr-Abl may be promising targets for the development of immunotherapeutical approaches against myeloid leukemia of different origin.

High microparticle concentration in cord plasma

We investigated if differences in the microparticle concentration and activity between newborn cord plasma and adult plasma exist.

METHODS

To enumerate and characterize microparticles (MP) FACS and ELISA were used.The effect of microparticles derived tissue factor (TF) on thrombin generation was measured indirectly by CAT (calibrated automated thrombography).

RESULTS

The flow cytometric measurements revealed an increased microparticle concentration in newborn cord compared with adult plasma. By the use of ELISA a significantly increased procoagulant activity of microparticles was found in newborn cord plasma as compared to adult plasma. Initiation of thrombin generation by adding phospholipids alone resulted in a significant lower prolongation of the lag time, time to peak in cord plasma, while the decrease of endogenous thrombin potential (ETP) and peak was comparable between newborns and adults.

CONCLUSION

Our results show a higher impact of microparticles on the haemostatic system of newborns than on that of adults. The three methods suggest a somewhat increased microparticle activity in newborn cord plasma, but argue against strong platelet activation during birth.

Relationship between thrombin generation and carotid intima-media thickness

Increasing evidence indicates that thrombin plays a role not only in thrombosis but also in the progression of atherosclerosis.

AIM

The relationship between thrombin generation and intima-media thickness (IMT) as an index of subclinical atherosclerosis was investigated. Participants, material, methods: We examined 163 asymptomatic middle-aged persons free of overt clinical atherosclerotic disease. They underwent ultrasonography of the common carotid arteries. In addition, thrombin generation was measured by means of CAT (calibrated automated thrombography). For our study we divided the healthy study participants into three age groups (<45, 45-60 and >60 years).

RESULTS

A significant positive correlation was seen between endogenous thrombin potential (ETP) (p = 0.012), time to peak (TTP) (p = 0.033) start tail (p = 0.007) and carotid IMT in the group of healthy volunteers younger than 45 years.

CONCLUSION

We demonstrated that in adults younger than 45 years without clinically overt atherosclerotic disease ETP was significantly associated with carotid IMT. It is tempting to speculate that ETP may serve as an index for subclinical atherosclerosis in persons below 45 years.

No differences in support of thrombin generation by neonatal or adult platelets

Newborns have, despite low clotting factors and poor in vitro platelet function, a well functioning hemostasis. The reason for this is still not completely clear. The aim of our study was to investigate whether phospholipids in neonatal platelets differ from those in adult platelets in their total amount, in their exposure on the platelet surface, and their effect on thrombin generation (TG).

METHODS

Clotting times of newborn and adult platelet-rich plasma were measured. Effect of newborn and adult platelets on TG was measured by means of CAT (calibrated automated thrombography). In addition, the effect of newborn and adult platelets with or without stimulation by ionophor on TG was measured in a purified prothrombinase complex. Phosphatidylserine-exposure (PS) of newborn and adult platelets was measured by flow cytometry of annexin V binding. The amount of phospholipids (PL) was determined by means of mass spectrometry.

RESULTS

Clotting times of platelet-rich plasma (PRP) of newborns stimulated with ionophor showed a significant lower reduction of clotting time than in adult PRP. No differences in the support of TG between neonatal and adult platelets were found in neonatal or adult plasma by means of CAT. In the purified system TG was increased by adding ionophor stimulated platelets but no difference was evident between stimulated newborn and adult platelets. Flow cytometric analysis showed no difference in annexin V binding between adult and newborn platelets. The results of mass spectrometry showed a very similar amount and pattern of PL of adult and newborns platelets.

CONCLUSION

Our results do not provide any evidence that a different PL content or expression of neonatal platelets may alter TG in neonates.

Calibrated automated thrombin generation in paediatric patients with inflammatory bowel disease

In adults, inflammatory bowel disease (IBD) is associated with an increased risk of thromboembolic complications. The pathogenesis of IBD is not really clear and a high thrombin activity might contribute to disease progression. We wanted to see whether children with IBD have a higher thrombin generation (TG).

PATIENTS, MATERIAL, METHODS

Plasma samples were collected of 20 patients with IBD and of 60 healthy controls (age range from 10 to 19). TG was measured by means of Calibrated automated thrombography (CAT). The disease activity was estimated, using the Pediatric Crohn's Disease Activity Index (PCDAI) for Crohn's disease and the Pediatric Ulcerative Colitis Disease Activity Index (PUCAI) for Ulcerative Colitis. In addition, we investigated F1+F2, TAT, TFPI and fibrinogen.

RESULTS

There was a significant increase of endogenous thrombin potential (ETP), lag time and time to peak in patients with IBD, while peak showed no difference to healthy controls. ETP and F1+F2 in children with IBD also showed a significant correlation with PCDAI (PUCAI) and fibrinogen.

CONCLUSION

IBD in children is associated with high TG, but this seems to be caused mainly by the inflammatory process and not by any individual disposition.

Malignant stroke in an adolescent with a homozygous MTHFR 677CT mutation and intake of hormonal contraceptives

Severe stroke in children and adolescents with its devastating long term consequences remains a rare disorder with many open questions. Beside the well known risk factors such as infection or congenital and acquired heart disease, coagulation disorders have to be considered in the differential work up of the underlying aetiology. Here we report the case of an adolescent with a homozygote MTHFR 677CT mutation suffering a malignant stroke shortly after the start of oral contraceptives.

CONCLUSION

Since prevention seems easily feasible, general screening for MTHFR mutations might be worthwhile in women before starting oral contraceptives.

Allorestricted T lymphocytes with a high avidity T-cell receptor towards NY-ESO-1 have potent anti-tumor activity

The cancer-testis antigen NY-ESO-1 has been targeted as a tumor-associated antigen by immunotherapeutical strategies, such as cancer vaccines. The prerequisite for a T-cell-based therapy is the induction of T cells capable of recognizing the NY-ESO-1-expressing tumor cells. In this study, we generated human T lymphocytes directed against the immunodominant NY-ESO-1(157-165) epitope known to be naturally presented with HLA-A*0201. We succeeded to isolate autorestricted and allorestricted T lymphocytes with low, intermediate or high avidity TCRs against the NY-ESO-1 peptide. The avidity of the established CTL populations correlated with their capacity of lysing HLA-A2-positive, NY-ESO-1-expressing tumor cell lines derived from different origins, e.g. melanoma and myeloma. The allorestricted NY-ESO-1-specific T lymphocytes displayed TCRs with the highest avidity and best anti-tumor recognition activity. TCRs derived from allorestricted, NY-ESO-1-specific T cells may be useful reagents for redirecting primary T cells by TCR gene transfer and, therefore, may facilitate the development of adoptive transfer regimens based on TCR-transduced T cells for the treatment of NY-ESO-1-expressing hematological malignancies and solid tumors.

HLA-B*1832, a novel B allele was found through high-resolution HLA typing of a Spanish blood donor

In this paper, we describe the novel human leukocyte antigen (HLA)-B*1832 allele that we found in a female Spanish volunteer blood donor for clinical investigation during her high-resolution HLA typing. The HLA-B typing is B*1801, 1832, and the DNA sequence is homozygous with the exception characterized by a nucleotide exchange 'C' to 'A' at position 505, which, in consequence, replaced arginine at codon 169 (CGC) by serine in the new allele B*1832.

Redirection of human T lymphocytes towards HER2 by T cell receptor gene transfer for adoptive T cell transfer (41.6)

The clinical goal of our studies is the adoptive transfer of primary T cells transduced with a HER2-specific T cell receptor (TCR) for patients with HER2-overexpressing breast cancer.

HLA-A2-, CD8 T cells were stimulated with allogeneic HLA-A2+ dendritic cells (DC) pulsed with the peptide HER2369-377. HER2369-377-reactive T cells were screened, cloned and further tested in functional assays.

The TCR from the HER2-reactive CTL clone KU1 was cloned into a retrovirus. Primary T lymphocytes were transduced with this construct and functionally compared with the parental CTL clone KU1.

The TCR-transduced primary T cells recognized the peptide HER2369-377 exogenously loaded onto T2 cells or endogenously expressed by tumor cells and transfectants. Similar to the parental CTL clone KU1, the transgenic T cells were not only able to recognize HER2369-377, but also the corresponding peptides from HER3 and HER4. Following TCR optimization (codon optimization, murinization), the TCR-transduced T cells displayed an enhanced tumor cell recognition.

In conclusion, the fine specificity of a HER2-reactive TCR is conserved following transduction into primary T lymphocytes. These results facilitate the design of HER2-directed immunotherapies based on TCR-transduced T cells. The observed cross-recognition especially with HER3 may be beneficial as HER2 and HER3 overexpressing tumors are particularly aggressive.

DFG