Rapid anti-myeloma activity by T cells expressing an anti-BCMA CAR with a human heavy-chain-only antigen-binding domain

Multiple myeloma (MM) is a rarely curable malignancy of plasma cells. MM expresses B cell maturation antigen (BCMA). We developed a fully human anti-BCMA chimeric antigen receptor (CAR) with a heavy-chain-only antigen-recognition domain, a 4-1BB domain, and a CD3ζ domain. The CAR was designated FHVH33-CD8BBZ. We conducted the first-in-humans clinical trial of T cells expressing FHVH33-CD8BBZ (FHVH-T). Twenty-five patients with relapsed MM were treated. The stringent complete response rate (sCR) was 52%. Median progression-free survival (PFS) was 78 weeks. Of 24 evaluable patients, 6 (25%) had a maximum cytokine-release syndrome (CRS) grade of 3; no patients had CRS of greater than grade 3. Most anti-MM activity occurred within 2-4 weeks of FHVH-T infusion as shown by decreases in the rapidly changing MM markers serum free light chains, urine light chains, and bone marrow plasma cells. Blood CAR+ cell levels peaked during the time that MM elimination was occurring, between 7 and 15 days after FHVH-T infusion. C-C chemokine receptor type 7 (CCR7) expression on infusion CD4+ FHVH-T correlated with peak blood FHVH-T levels. Single-cell RNA sequencing revealed a shift toward more differentiated FHVH-T after infusion. Anti-CAR antibody responses were detected in 4 of 12 patients assessed. FHVH-T has powerful, rapid, and durable anti-MM activity.

Phenotypic signatures of circulating neoantigen-reactive CD8+ T cells in patients with metastatic cancers

Circulating T cells from peripheral blood (PBL) can provide a rich and noninvasive source for antitumor T cells. By single-cell transcriptomic profiling of 36 neoantigen-specific T cell clones from 6 metastatic cancer patients, we report the transcriptional and cell surface signatures of antitumor PBL-derived CD8+ T cells (NeoTCRPBL). Comparison of tumor-infiltrating lymphocyte (TIL)- and PBL-neoantigen-specific T cells revealed that NeoTCRPBL T cells are low in frequency and display less-dysfunctional memory phenotypes relative to their TIL counterparts. Analysis of 100 antitumor TCR clonotypes indicates that most NeoTCRPBL populations target the same neoantigens as TILs. However, NeoTCRPBL TCR repertoire is only partially shared with TIL. Prediction and testing of NeoTCRPBL signature-derived TCRs from PBL of 6 prospective patients demonstrate high enrichment of clonotypes targeting tumor mutations, a viral oncogene, and patient-derived tumor. Thus, the NeoTCRPBL signature provides an alternative source for identifying antitumor T cells from PBL of cancer patients, enabling immune monitoring and immunotherapies.

Neoantigen Identification and Response to Adoptive Cell Transfer in Anti-PD-1 Naïve and Experienced Patients with Metastatic Melanoma

PURPOSE

Immune checkpoint blockade (ICB) agents and adoptive cell transfer (ACT) of tumor-infiltrating lymphocytes (TIL) are prominent immunotherapies used for the treatment of advanced melanoma. Both therapies rely on activation of lymphocytes that target shared tumor antigens or neoantigens. Recent analysis of patients with metastatic melanoma who underwent treatment with TIL ACT at the NCI demonstrated decreased responses in patients previously treated with anti-PD-1 agents. We aimed to find a basis for the difference in response rates between anti-PD-1 naïve and experienced patients.

PATIENTS AND METHODS

We examined the tumor mutational burden (TMB) of resected tumors and the repertoire of neoantigens targeted by autologous TIL in a cohort of 112 anti-PD-1 naïve and 69 anti-PD-1 experienced patients.

RESULTS

Anti-PD-1 naïve patients were found to possess tumors with higher TMBs (352.0 vs. 213.5, P = 0.005) and received TIL reactive with more neoantigens (2 vs. 1, P = 0.003) compared with anti-PD-1 experienced patients. Among patients treated with TIL ACT, TMB and number of neoantigens identified were higher in ACT responders than ACT nonresponders in both anti-PD-1 naïve and experienced patients. Among patients with comparable TMBs and predicted neoantigen loads, treatment products administered to anti-PD-1 naïve patients were more likely to contain T cells reactive against neoantigens than treatment products for anti-PD-1 experienced patients (2.5 vs. 1, P = 0.02).

CONCLUSIONS

These results indicate that decreases in TMB and targeted neoantigens partially account for the difference in response to ACT and that additional factors likely influence responses in these patients. See related commentary by Blass and Ott, p. 2980.

Adoptive Cellular Therapy with Autologous Tumor-Infiltrating Lymphocytes and T-cell Receptor-Engineered T Cells Targeting Common p53 Neoantigens in Human Solid Tumors

Adoptive cellular therapy (ACT) targeting neoantigens can achieve durable clinical responses in patients with cancer. Most neoantigens arise from patient-specific mutations, requiring highly individualized treatments. To broaden the applicability of ACT targeting neoantigens, we focused on TP53 mutations commonly shared across different cancer types. We performed whole-exome sequencing on 163 patients with metastatic solid cancers, identified 78 who had TP53 missense mutations, and through immunologic screening, identified 21 unique T-cell reactivities. Here, we report a library of 39 T-cell receptors (TCR) targeting TP53 mutations shared among 7.3% of patients with solid tumors. These TCRs recognized tumor cells in a TP53 mutation- and human leucocyte antigen (HLA)-specific manner in vitro and in vivo. Twelve patients with chemorefractory epithelial cancers were treated with ex vivo-expanded autologous tumor-infiltrating lymphocytes (TIL) that were naturally reactive against TP53 mutations. However, limited clinical responses (2 partial responses among 12 patients) were seen. These infusions contained low frequencies of mutant p53-reactive TILs that had exhausted phenotypes and showed poor persistence. We also treated one patient who had chemorefractory breast cancer with ACT comprising autologous peripheral blood lymphocytes transduced with an allogeneic HLA-A*02-restricted TCR specific for p53R175H. The infused cells exhibited an improved immunophenotype and prolonged persistence compared with TIL ACT and the patient experienced an objective tumor regression (-55%) that lasted 6 months. Collectively, these proof-of-concept data suggest that the library of TCRs targeting shared p53 neoantigens should be further evaluated for the treatment of patients with advanced human cancers. See related Spotlight by Klebanoff .

Breast Cancers Are Immunogenic: Immunologic Analyses and a Phase II Pilot Clinical Trial Using Mutation-Reactive Autologous Lymphocytes

PURPOSE

Metastatic breast cancer (mBrCa) is most often an incurable disease with only modest responses to available immunotherapies. This study investigates the immunogenicity of somatic mutations in breast cancer and explores the therapeutic efficacy in a pilot trial of mutation-reactive tumor-infiltrating lymphocytes (TILs) in patients with metastatic disease.

PATIENTS AND METHODS

Forty-two patients with mBrCa refractory to previous lines of treatment underwent surgical resection of a metastatic lesion(s), isolation of TIL cultures, identification of exomic nonsynonymous tumor mutations, and immunologic screening for neoantigen reactivity. Clinically eligible patients with appropriate reactivity were enrolled into one cohort of an ongoing phase II pilot trial of adoptive cell transfer of selected neoantigen-reactive TIL, with a short course of pembrolizumab (ClinicalTrials.gov identifier: NCT01174121).

RESULTS

TILs were isolated and grown in culture from the resected lesions of all 42 patients with mBrCa, and a median number of 112 (range: 6-563) nonsynonymous mutations per patient were identified. Twenty-eight of 42 (67%) patients contained TIL that recognized at least one immunogenic somatic mutation (median: 3 neoantigens per patient, range: 1-11), and 13 patients demonstrated robust reactivity appropriate for adoptive transfer. Eight patients remained clinically eligible for treatment, and six patients were enrolled on a protocol of adoptive cell transfer of enriched neoantigen-specific TIL, in combination with pembrolizumab (≤ 4 doses). Objective tumor regression was noted in three patients, including one complete response (now ongoing over 5.5 years) and two partial responses (6 and 10 months).

CONCLUSION

Most patients with breast cancer generated a natural immune response targeting the expressed products of their cancer mutations. Adoptive transfer of TIL is a highly personalized experimental option for patients with mBrCa shown to be capable of mediating objective responses in this pilot trial and deserves further study.

A phenotypic signature that identifies neoantigen-reactive T cells in fresh human lung cancers

A common theme across multiple successful immunotherapies for cancer is the recognition of tumor-specific mutations (neoantigens) by T cells. The rapid discovery of such antigen responses could lead to improved therapies through the adoptive transfer of T cells engineered to express neoantigen-reactive T cell receptors (TCRs). Here, through CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing) and TCR-seq of non-small cell lung cancer (NSCLC) tumor-infiltrating lymphocytes (TILs), we develop a neoantigen-reactive T cell signature based on clonotype frequency and CD39 protein and CXCL13 mRNA expression. Screening of TCRs selected by the signature allows us to identify neoantigen-reactive TCRs with a success rate of 45% for CD8+ and 66% for CD4+ T cells. Because of the small number of samples analyzed (4 patients), generalizability remains to be tested. However, this approach can enable the quick identification of neoantigen-reactive TCRs and expedite the engineering of personalized neoantigen-reactive T cells for therapy.

Molecular signatures of antitumor neoantigen-reactive T cells from metastatic human cancers

The accurate identification of antitumor T cell receptors (TCRs) represents a major challenge for the engineering of cell-based cancer immunotherapies. By mapping 55 neoantigen-specific TCR clonotypes (NeoTCRs) from 10 metastatic human tumors to their single-cell transcriptomes, we identified signatures of CD8⁺ and CD4⁺ neoantigen-reactive tumor-infiltrating lymphocytes (TILs). Neoantigen-specific TILs exhibited tumor-specific expansion with dysfunctional phenotypes, distinct from blood-emigrant bystanders and regulatory TILs. Prospective prediction and testing of 73 NeoTCR signature-derived clonotypes demonstrated that half of the tested TCRs recognized tumor antigens or autologous tumors. NeoTCR signatures identified TCRs that target driver neoantigens and nonmutated viral or tumor-associated antigens, suggesting a common metastatic TIL exhaustion program. NeoTCR signatures delineate the landscape of TILs across metastatic tumors, enabling successful TCR prediction based purely on TIL transcriptomic states for use in cancer immunotherapy.

Tumor MHC Class I Expression Associates with Intralesional Interleukin-2 Response in Melanoma

Cancer immunotherapy can result in lasting tumor regression, but predictive biomarkers of treatment response remain ill-defined. Here, we performed single-cell proteomics, transcriptomics, and genomics on matched untreated and interleukin-2 (IL-2) injected metastases from patients with melanoma. Lesions that completely regressed following intralesional IL-2 harbored increased fractions and densities of non-proliferating CD8+ T cells lacking expression of PD-1, LAG-3 and TIM-3 (PD-1-LAG-3-TIM-3-). Untreated lesions from patients who subsequently responded with complete eradication of all tumor cells in all injected lesions (individuals referred to herein as "extreme responders") were characterized by proliferating CD8+ T cells with an exhausted phenotype (PD-1+LAG-3+TIM-3+), stromal B-cell aggregates, and expression of IFNgamma and IL-2 response genes. Loss of membranous MHC class I expression in tumor cells of untreated lesions was associated with resistance to IL-2 therapy. We validated this finding in an independent cohort of metastatic melanoma patients treated with intralesional or systemic IL-2. Our study suggests that intact tumor cell antigen presentation is required for melanoma response to IL-2 and describes a multi-dimensional and spatial approach to develop immuno-oncology biomarker hypotheses using routinely collected clinical biospecimens.

Impact of Prior Treatment on the Efficacy of Adoptive Transfer of Tumor-Infiltrating Lymphocytes in Patients with Metastatic Melanoma

PURPOSE

Adoptive cell transfer (ACT) of autologous tumor-infiltrating lymphocytes (TIL) can mediate durable responses in patients with metastatic melanoma. This retrospective analysis provides long-term follow-up and describes the effect of prior therapy on outcomes after ACT-TIL.

PATIENTS AND METHODS

Patients with metastatic melanoma underwent surgical resection of a tumor for generation of TILs and were treated with a lymphodepleting preparative regimen followed by adoptive transfer of TILs and intravenous IL2. Clinical characteristics of enrolled patients and treatment characteristics of TIL infusion products over two decades of ACT were analyzed to identify predictors of objective response.

RESULTS

Adoptive transfer of TILs mediated an objective response rate of 56% (108/192) and median melanoma-specific survival of 28.5 months in patients naïve to anti-programmed cell death-1 (PD-1) therapy compared with 24% (8/34) and 11.6 months in patients refractory to anti-PD-1 (aPD-1). Among patients with BRAF V600E/K-mutated disease, prior treatment with targeted molecular therapy was also associated with a decreased response rate (21% vs. 60%) and decreased survival (9.3 vs. 50.7 months) when compared with those patients naïve to targeted therapy. With a median potential follow-up of 89 months, 46 of 48 complete responders in the aPD-1-naïve cohort have ongoing responses after a single treatment and 10-year melanoma-specific survival of 96%.

CONCLUSIONS

Patients previously treated with PD-1 or MAPK inhibition are significantly less likely to develop durable objective responses to ACT-TIL. While ACT-TIL is currently being investigated for treatment-refractory patients, it should also be considered as an initial treatment option for eligible patients with metastatic melanoma.

Identification of neoantigen-reactive T lymphocytes in the peripheral blood of a patient with glioblastoma

The adoptive transfer of naturally occurring T cells that recognize cancer neoantigens has led to durable tumor regressions in select patients with cancer. However, it remains unknown whether such T cells can be isolated from and used to treat patients with glioblastoma, a cancer that is refractory to currently available therapies. To answer this question, we stimulated patient blood-derived memory T cells in vitro using peptides and minigenes that represented point mutations unique to patients’ tumors (ie, candidate neoantigens) and then tested their ability to specifically recognize these mutations. In a cohort of five patients with glioblastoma, we found that circulating CD4⁺ memory T cells from one patient recognized a cancer neoantigen harboring a mutation in the EED gene (EED^H189N) that was unique to that patient’s tumor. This finding suggests that neoantigen-reactive T cells could indeed be isolated from patients with glioblastoma, thereby providing a rationale for further efforts to develop neoantigen-directed adoptive T cell therapy for this disease.

mRNA vaccine-induced neoantigen-specific T cell immunity in patients with gastrointestinal cancer

BACKGROUNDTherapeutic vaccinations against cancer have mainly targeted differentiation antigens, cancer-testis antigens, and overexpressed antigens and have thus far resulted in little clinical benefit. Studies conducted by multiple groups have demonstrated that T cells recognizing neoantigens are present in most cancers and offer a specific and highly immunogenic target for personalized vaccination.METHODSWe recently developed a process using tumor-infiltrating lymphocytes to identify the specific immunogenic mutations expressed in patients' tumors. Here, validated, defined neoantigens, predicted neoepitopes, and mutations of driver genes were concatenated into a single mRNA construct to vaccinate patients with metastatic gastrointestinal cancer.RESULTSThe vaccine was safe and elicited mutation-specific T cell responses against predicted neoepitopes not detected before vaccination. Furthermore, we were able to isolate and verify T cell receptors targeting KRASG12D mutation. We observed no objective clinical responses in the 4 patients treated in this trial.CONCLUSIONThis vaccine was safe, and potential future combination of such vaccines with checkpoint inhibitors or adoptive T cell therapy should be evaluated for possible clinical benefit in patients with common epithelial cancers.TRIAL REGISTRATIONPhase I/II protocol (NCT03480152) was approved by the IRB committee of the NIH and the FDA.FUNDINGCenter for Clinical Research, NCI, NIH.

Stem-like CD8 T cells mediate response of adoptive cell immunotherapy against human cancer

Adoptive T cell therapy (ACT) using ex vivo-expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate complete regression of certain human cancers. The impact of TIL phenotypes on clinical success of TIL-ACT is currently unclear. Using high-dimensional analysis of human ACT products, we identified a memory-progenitor CD39-negative stem-like phenotype (CD39^-CD69^-) associated with complete cancer regression and TIL persistence and a terminally differentiated CD39-positive state (CD39⁺CD69⁺) associated with poor TIL persistence. Most antitumor neoantigen-reactive TILs were found in the differentiated CD39⁺ state. However, ACT responders retained a pool of CD39^- stem-like neoantigen-specific TILs that was lacking in ACT nonresponders. Tumor-reactive stem-like TILs were capable of self-renewal, expansion, persistence, and superior antitumor response in vivo. These data suggest that TIL subsets mediating ACT response are distinct from TIL subsets enriched for antitumor reactivity.

The Role of Immune Cells in Breast Tissue and Immunotherapy for the Treatment of Breast Cancer

Immune cells are present in normal breast tissue and in breast carcinoma. The nature and distribution of the immune cell subtypes in these tissues are reviewed to promote a better understanding of their important role in breast cancer prevention and treatment. We conducted a review of the literature to define the type, location, distribution, and role of immune cells in normal breast tissue and in in situ and invasive breast cancer. Immune cells in normal breast tissue are located predominantly within the epithelial component in breast ductal lobules. Immune cell subtypes representing innate immunity (NK, CD68+, and CD11c+ cells) and adaptive immunity (most commonly CD8+, but CD4+ and CD20+ as well) are present; CD8+ cells are the most common subtype and are primarily effector memory cells. Immune cells may recognize neoantigens and endogenous and exogenous ligands and may serve in chronic inflammation and immunosurveillance. Progression to breast cancer is characterized by increased immune cell infiltrates in tumor parenchyma and stroma, including CD4+ and CD8+ granzyme B+ cytotoxic T cells, B cells, macrophages and dendritic cells. Tumor-infiltrating lymphocytes in breast cancer may serve as prognostic indicators for response to chemotherapy and for survival. Experimental strategies of adoptive transfer of breast tumor-infiltrating lymphocyte may allow regression of metastatic breast cancer and encourage development of innovative T-cell strategies for the immunotherapy of breast cancer. In conclusion, immune cells in breast tissues play an important role throughout breast carcinogenesis. An understanding of these roles has important implications for the prevention and the treatment of breast cancer.

Defining best practices for tissue procurement in immuno-oncology clinical trials: consensus statement from the Society for Immunotherapy of Cancer Surgery Committee

Immunotherapy is now a cornerstone for cancer treatment, and much attention has been placed on the identification of prognostic and predictive biomarkers. The success of biomarker development is dependent on accurate and timely collection of biospecimens and high-quality processing, storage and shipping. Tumors are also increasingly used as source material for the generation of therapeutic T cells. There have been few guidelines or consensus statements on how to optimally collect and manage biospecimens and source material being used for immunotherapy and related research. The Society for Immunotherapy of Cancer Surgery Committee has brought together surgical experts from multiple subspecialty disciplines to identify best practices and to provide consensus on how best to access and manage specific tissues for immuno-oncology treatments and clinical investigation. In addition, the committee recommends early integration of surgeons and other interventional physicians with expertise in biospecimen collection, especially in clinical trials, to optimize the quality of tissue and the validity of correlative clinical studies in cancer immunotherapy.

Long-Term Follow-Up of Anti-CD19 Chimeric Antigen Receptor T-Cell Therapy

PURPOSE

Anti-CD19 chimeric antigen receptors (CARs) are artificial fusion proteins that cause CD19-specific T-cell activation. Durability of remissions and incidence of long-term adverse events are critical factors determining the utility of anti-CD19 CAR T-cell therapy, but long-term follow-up of patients treated with anti-CD19 CAR T cells is limited. This work provides the longest follow-up of patients in remission after anti-CD19 CAR T-cell therapy.

METHODS

Between 2009 and 2015, we administered 46 CAR T-cell treatments to 43 patients (ClinicalTrials.gov identifier: NCT00924326). Patients had relapsed B-cell malignancies of the following types: diffuse large B-cell lymphoma or primary mediastinal B-cell lymphoma (DLBCL/PMBCL; n = 28), low-grade B-cell lymphoma (n = 8), or chronic lymphocytic leukemia (CLL; n = 7). This report focuses on long-term outcomes of these patients. The CAR used was FMC63-28Z; axicabtagene ciloleucel uses the same CAR. Cyclophosphamide plus fludarabine conditioning chemotherapy was administered before CAR T cells.

RESULTS

The percentages of CAR T-cell treatments resulting in a > 3-year duration of response (DOR) were 51% (95% CI, 35% to 67%) for all evaluable treatments, 48% (95% CI, 28% to 69%) for DLBCL/PMBCL, 63% (95% CI, 25% to 92%) for low-grade lymphoma, and 50% (95% CI, 16% to 84%) for CLL. The median event-free survival of all 45 evaluable treatments was 55 months. Long-term adverse effects were rare, except for B-cell depletion and hypogammaglobulinemia. Median peak blood CAR-positive cell levels were higher among patients with a DOR of > 3 years (98/µL; range, 9-1,217/µL) than among patients with a DOR of < 3 years (18/µL; range, 0-308/μL, P = .0051).

CONCLUSION

Complete remissions of a variety of B-cell malignancies lasting ≥ 3 years occurred after 51% of evaluable anti-CD19 CAR T-cell treatments. Remissions of up to 9 years are ongoing. Late adverse events were rare.

Incidence of Asymptomatic Brain Metastases in Metastatic Colorectal Cancer

BACKGROUND

Current literature suggests that brain metastasis is an infrequent occurrence in metastatic colorectal cancer. Outside of rare autopsy studies, these retrospective reports describe the incidence of symptomatic brain metastasis and therefore lack a description of the incidence in asymptomatic patients. With improved survival and a lack of routine brain imaging, the true incidence of brain metastasis among patients with metastatic colorectal cancer is likely under-recognized. At our research institution, protocol criteria require brain imaging regardless of neurologic symptoms. Therefore, we aim to describe the incidence of asymptomatic brain metastases in patients with metastatic colorectal cancer.

PATIENTS AND METHODS

This study included patients with metastatic colorectal cancer enrolled onto a clinical trial screening protocol at the National Cancer Institute that underwent brain imaging (n = 171) between 2010 and 2019.

RESULTS

The median age of patients at initial colorectal cancer diagnosis was 48.1 years. Most had stage IV disease with synchronous metastases. Twenty-five (14.6%) patients were identified with brain metastases, of which 19 (76%) were asymptomatic. Those with asymptomatic lesions were more likely to have presented with synchronous metastases, have a shorter time from primary diagnosis to development of metastatic disease, and have smaller brain metastases.

CONCLUSION

We identified a high number of asymptomatic brain metastasis and subsequently a higher cumulative incidence of brain metastases in patients with metastatic colorectal cancer than historical reports would suggest. This may represent a heretofore unknown aspect of the natural course of disease now being exposed owing to an increasing life expectancy of these patients and could play a pivotal role in therapeutic decisions.

Long-term follow-up of anti-CD19 CAR T-cell therapy for B-cell lymphoma and chronic lymphocytic leukemia

3012

Background: T cells expressing anti-CD19 chimeric antigen receptors (CARs) can cause complete remissions of relapsed lymphoma. We conducted the first clinical trial of anti-CD19 CAR T cells to show responses against lymphoma. This CAR was later developed as axicabtagene ciloleucel. Here, we aimed to assess the long-term durability of remissions and the long-term adverse effects after anti-CD19 CAR T-cell therapy. Methods: Between 2009 and 2015, we treated 43 patients with anti-CD19 CAR T cells preceded by conditioning chemotherapy of cyclophosphamide plus fludarabine (NCT00924326). Three patients were re-treated for a total of 46 CAR T-cell treatments. Twenty-eight patients had aggressive lymphoma (diffuse large B-cell lymphoma or primary mediastinal B cell lymphoma), eight patients had low-grade lymphoma (five with follicular lymphoma and 1 each with splenic marginal zone lymphoma, mantle cell lymphoma, and unspecified low-grade non-Hodgkin lymphoma), and seven patients had chronic lymphocytic leukemia (CLL). Patients were treated in three cohorts that differed in the CAR T-cell production process and conditioning chemotherapy dose. Results: Of the 43 treated patients, 63% had chemotherapy-refractory lymphoma. Patients had received a median of 4 previous lines of therapy. The median CAR+ T cell dose per kilogram was 2X10^6. The overall remission rate was 76% with 54% complete remissions (CR) and 22% partial remissions (PR). Patients with CR had higher median peak blood CAR levels (86 CAR+ cells/µL) than those who did not have CR (16 CAR+ cells/µL, P= 0.0041). Long-term adverse effects were rare except for B-cell depletion and hypogammaglobulinemia, which both improved over time. Conclusions: This is the longest follow-up study of patients who received anti-CD19 CAR T cells. Anti-CD19 CAR T cells cause highly durable remissions of relapsed B-cell lymphoma and CLL, and long-term adverse effects of anti-CD19 CAR T cells were rare and usually mild. Clinical trial information: NCT00924326 . [Table: see text]

And Now for Something Completely Different: Immunotherapy Beyond Checkpoints in Melanoma

Advances in the understanding of biology and therapy of melanoma have occurred at an astonishing pace over the past approximately 15 years, and successful melanoma therapy has led the way for similar advances in many other solid tumors that are continuing to improve outcomes for all patients with cancer. Although the 2018 Nobel Prize was awarded to two investigators who discovered that therapeutic targeting of immune checkpoints held the key to major patient benefits, there are many additional immunotherapeutic strategies that warrant further study and discussion at scientific and medical meetings. This article provides the newest information on three areas of immunotherapy that have been successfully applied to melanoma and continue to pave the way for new developments: cytokines, adoptive cell therapies (ADTs), and intratumoral injection of immunomodulatory agents.

Unique Neoantigens Arise from Somatic Mutations in Patients with Gastrointestinal Cancers

Immunotherapies can mediate regression of human tumors with high mutation rates, but responses are rarely observed in patients with common epithelial cancers. This raises the question of whether patients with these common cancers harbor T lymphocytes that recognize mutant proteins expressed by autologous tumors that may represent ideal targets for immunotherapy. Using high-throughput immunologic screening of mutant gene products identified via whole-exome sequencing, we identified neoantigen-reactive tumor-infiltrating lymphocytes (TIL) from 62 of 75 (83%) patients with common gastrointestinal cancers. In total, 124 neoantigen-reactive TIL populations were identified, and all but one of the neoantigenic determinants were unique. The results of in vitro T-cell recognition assays demonstrated that 1.6% of the gene products encoded by somatic nonsynonymous mutations were immunogenic. These findings demonstrate that the majority of common epithelial cancers elicit immune recognition and open possibilities for cell-based immunotherapies for patients bearing these cancers. SIGNIFICANCE: TILs cultured from 62 of 75 (83%) patients with gastrointestinal cancers recognized neoantigens encoded by 1.6% of somatic mutations expressed by autologous tumor cells, and 99% of the neoantigenic determinants appeared to be unique and not shared between patients.This article is highlighted in the In This Issue feature, p. 983.

An Update on Adoptive T-Cell Therapy and Neoantigen Vaccines

Adoptive T-cell therapy using tumor-infiltrating lymphocytes (TILs) has demonstrated long-lasting antitumor activity in select patients with advanced melanoma. Cancer vaccines have been used for many decades and have shown some promise but overall relatively modest clinical activity across cancers. Technological advances in genome sequencing capabilities and T-cell engineering have had substantial impact on both adoptive cell therapy and the cancer vaccine field. The ability to identify neoantigens-a class of tumor antigens that is truly tumor specific and encoded by tumor mutations through rapid and relatively inexpensive next-generation sequencing-has already demonstrated the critical importance of these antigens as targets of antitumor-specific T-cell responses in the context of immune checkpoint blockade and other immunotherapies. Therapeutically targeting these antigens with either adoptive T-cell therapy or vaccine approaches has demonstrated early promise in the clinic in patients with advanced solid tumors. Chimeric antigen receptor (CAR) T cells, which are engineered by fusing an antigen-specific, single-chain antibody (scFv) with signaling molecules of the T-cell receptor (TCR)/CD3 complex creating an antibody-like structure on T cells that recognizes antigens independently of major histocompatibility complex (MHC) molecules, have demonstrated remarkable clinical activity in patients with advanced B-cell malignancies, leading to several approvals by the U.S. Food and Drug Administration (FDA).

BRAF Inhibition: Bridge or Boost to T-cell Therapy?

The concept of treatment-refractory disease has evolved as checkpoint modulation has changed the therapeutic landscape for patients with metastatic melanoma. Developing meaningful salvage strategies will involve the exploration of combination therapies and new immunotherapeutics, including adoptive transfer of tumor-infiltrating lymphocytes or other T-cell-based therapy.See related article by Atay et al., p. 2783.

Immune recognition of somatic mutations leading to complete durable regression in metastatic breast cancer

Immunotherapy using either checkpoint blockade or the adoptive transfer of antitumor lymphocytes has shown effectiveness in treating cancers with high levels of somatic mutations-such as melanoma, smoking-induced lung cancers and bladder cancer-with little effect in other common epithelial cancers that have lower mutation rates, such as those arising in the gastrointestinal tract, breast and ovary^1-7. Adoptive transfer of autologous lymphocytes that specifically target proteins encoded by somatically mutated genes has mediated substantial objective clinical regressions in patients with metastatic bile duct, colon and cervical cancers^8-11. We present a patient with chemorefractory hormone receptor (HR)-positive metastatic breast cancer who was treated with tumor-infiltrating lymphocytes (TILs) reactive against mutant versions of four proteins-SLC3A2, KIAA0368, CADPS2 and CTSB. Adoptive transfer of these mutant-protein-specific TILs in conjunction with interleukin (IL)-2 and checkpoint blockade mediated the complete durable regression of metastatic breast cancer, which is now ongoing for >22 months, and it represents a new immunotherapy approach for the treatment of these patients.

Outcomes of Adoptive Cell Transfer With Tumor-infiltrating Lymphocytes for Metastatic Melanoma Patients With and Without Brain Metastases

Brain metastases cause significant morbidity and mortality in patients with metastatic melanoma. Although adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) can achieve complete and durable remission of advanced cutaneous melanoma, the efficacy of this therapy for brain metastases is unclear. Records of patients with M1c melanoma treated with ACT using TIL, including patients with treated and untreated brain metastases, were analyzed. Treatment consisted of preparative chemotherapy, autologous TIL infusion, and high-dose interleukin-2. Treatment outcomes, sites of initial tumor progression, and overall survival were analyzed. Among 144 total patients, 15 patients with treated and 18 patients with untreated brain metastases were identified. Intracranial objective responses (OR) occurred in 28% patients with untreated brain metastases. The systemic OR rates for patients with M1c disease without identified brain disease, treated brain disease, and untreated brain disease, and were 49%, 33% and 33%, respectively, of which 59%, 20% and 16% were durable at last follow-up. The site of untreated brain disease was the most likely site of initial tumor progression (61%) in patients with untreated brain metastases. Overall, we found that ACT with TIL can eliminate small melanoma brain metastases. However, following TIL therapy these patients frequently progress in the brain at a site of untreated brain disease. Patients with treated or untreated brain disease are less likely to achieve durable systemic ORs following TIL therapy compared with M1c disease and no history of brain disease. Melanoma brain metastases likely require local therapy despite the systemic effect of ACT.

Treatment of Patients With Metastatic Cancer Using a Major Histocompatibility Complex Class II-Restricted T-Cell Receptor Targeting the Cancer Germline Antigen MAGE-A3

Purpose Adoptive transfer of genetically modified T cells is being explored as a treatment for patients with metastatic cancer. Most current strategies use genes that encode major histocompatibility complex (MHC) class I-restricted T-cell receptors (TCRs) or chimeric antigen receptors to genetically modify CD8⁺ T cells or bulk T cells for treatment. Here, we evaluated the safety and efficacy of an adoptive CD4⁺ T-cell therapy using an MHC class II-restricted, HLA-DPB1*0401-restricted TCR that recognized the cancer germline antigen, MAGE-A3 (melanoma-associated antigen-A3). Patients and Methods Patients received a lymphodepleting preparative regimen, followed by adoptive transfer of purified CD4⁺ T cells, retrovirally transduced with MAGE-A3 TCR plus systemic high-dose IL-2. A cell dose escalation was conducted, starting at 10⁷ total cells and escalating at half-log increments to approximately 10¹¹ cells. Nine patients were treated at the highest dose level (0.78 to 1.23 × 10¹¹ cells). Results Seventeen patients were treated. During the cell dose-escalation phase, an objective complete response was observed in a patient with metastatic cervical cancer who received 2.7 × 10⁹ cells (ongoing at ≥ 29 months). Among nine patients who were treated at the highest dose level, objective partial responses were observed in a patient with esophageal cancer (duration, 4 months), a patient with urothelial cancer (ongoing at ≥ 19 months), and a patient with osteosarcoma (duration, 4 months). Most patients experienced transient fevers and the expected hematologic toxicities from lymphodepletion pretreatment. Two patients experienced transient grade 3 and 4 transaminase elevations. There were no treatment-related deaths. Conclusion These results demonstrate the safety and efficacy of administering autologous CD4⁺ T cells that are genetically engineered to express an MHC class II-restricted antitumor TCR that targets MAGE-A3. This clinical trial extends the reach of TCR gene therapy for patients with metastatic cancer.

Abstract 4982: Regression of metastatic breast cancer after adoptive cell transfer of tumor infiltrating lymphocytes and checkpoint blockade

Background: Adoptive transfer of tumor infiltrating lymphocytes (TIL) can effect long-term durable regression in patients with metastatic melanoma but has not been widely tested in common epithelial cancers. Similar to metastatic melanoma, recent studies on epithelial GI cancers report that tumor regressions can be mediated by adoptively transferred TIL recognizing non-synonymous somatic mutations. Breast cancer metastatic tumors are infiltrated by TIL and reactivity against autologous somatic mutations can be identified.

Methods: TIL were grown from a metastatic soft tissue tumor of a patient with hormone and chemotherapy-refractory ER+, HER2- breast cancer. DNA was extracted from tumor and matched normal peripheral blood samples for whole exome sequencing (WES) and RNAseq. Non-synonymous somatic mutations were identified and tested for potential recognition by autologous TIL using previously described tandem mini-gene and long peptide approaches. Recognition was assessed by IFN-γ release on ELISPOT and/or CD137 (4-1BB) upregulation with appropriate controls. Mutation reactive TIL were rapidly expanded in culture and transferred back to the patient. Adoptive cell transfer was preceded by a lymphodepleting preparative regimen and one dose of pembrolizumab. Cells were supported post-transfer with intravenous IL-2 administration, and pembrolizumab was administered for three additional doses. Deep sequencing of TCR rearrangement sequences was performed on the TIL and the pre- and post-infusion peripheral blood.

Results: The resected subcutaneous tumor no longer expressed ER and was negative for PD-L1 staining. WES/RNASeq identified 96 non-synonymous mutations for testing. Multiple CD4+ clones specifically recognizing a mutation expressed in the solute carrier SLC3A2 (p.K94T) and a single CD8+ clone recognizing a mutation in the proteasome-associated protein KIAA0368 (p.S186F) were identified with no recognition of wild-type peptides. These eight T cell clones constituted 23% of the infusion bag TIL. Nine months after transfer of 82x109 cells, the patient has an ongoing partial response, with target lesions down 96% from baseline, including multiple hepatic metastases and disabling brachial plexus adenopathy. Seven of the eight T cell clones with known reactivity persisted in the peripheral blood comprising 2.4% of all CDR3 sequences at 7 months. Only two of these TCR clones were detectable, with frequencies totaling 0.005%, in the pre-treatment circulation.

Conclusions: Tumor-infiltrating lymphocytes derived from a patient with metastatic breast cancer recognized tumor-specific non-synonymous somatic mutations, expanded in vitro and were used for adoptive cell transfer. TIL, co-administered with IL-2 and a short course of pembrolizumab, persisted in vivo and mediated regression of soft tissue, nodal and visceral metastases of breast cancer.

Citation Format: Nikolaos Zacharakis, Katarzyna Trebska-McGowan, Robert Somerville, Yong-Chen Lu, Anna Pasetto, Mary Black, Harshini Chinnasamy, Hui Xu, Jared J. Gartner, Todd D. Prickett, Paul F. Robbins, Steven A. Rosenberg, Stephanie L. Goff, Steven A. Feldman. Regression of metastatic breast cancer after adoptive cell transfer of tumor infiltrating lymphocytes and checkpoint blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4982. doi:10.1158/1538-7445.AM2017-4982

Treatment of metastatic uveal melanoma with adoptive transfer of tumour-infiltrating lymphocytes: a single-centre, two-stage, single-arm, phase 2 study

BACKGROUND

Uveal melanoma is a rare tumour with no established treatments once metastases develop. Although a variety of immune-based therapies have shown efficacy in metastatic cutaneous melanoma, their use in ocular variants has been disappointing. Recently, adoptive T-cell therapy has shown salvage responses in multiple refractory solid tumours. Thus, we sought to determine if adoptive transfer of autologous tumour-infiltrating lymphocytes (TILs) could mediate regression of metastatic uveal melanoma.

METHODS

In this ongoing single-centre, two-stage, phase 2, single-arm trial, patients (aged ≥16 years) with histologically confirmed metastatic ocular melanoma were enrolled. Key eligibility criteria were an Eastern Cooperative Oncology Group performance status of 0 or 1, progressive metastatic disease, and adequate haematological, renal, and hepatic function. Metastasectomies were done to procure tumour tissue to generate autologous TIL cultures, which then underwent large scale ex-vivo expansion. Patients were treated with lymphodepleting conditioning chemotherapy (intravenous cyclophosphamide [60 mg/kg] daily for 2 days followed by fludarabine [25 mg/m2] daily for 5 days, followed by a single intravenous infusion of autologous TILs and high-dose interleukin-2 [720 000 IU/kg] every 8 h). The primary endpoint was objective tumour response in evaluable patients per protocol using Response to Evaluation Criteria in Solid Tumors, version 1.0. An interim analysis of this trial is reported here. The trial is registered at ClinicalTrials.gov, number NCT01814046.

FINDINGS

From the completed first stage and ongoing expansion stage of this trial, a total of 21 consecutive patients with metastatic uveal melanoma were enrolled between June 7, 2013, and Sept 9, 2016, and received TIL therapy. Seven (35%, 95% CI 16-59) of 20 evaluable patients had objective tumour regression. Among the responders, six patients achieved a partial response, two of which are ongoing and have not reached maximum response. One patient achieved complete response of numerous hepatic metastases, currently ongoing at 21 months post therapy. Three of the responders were refractory to previous immune checkpoint blockade. Common grade 3 or worse toxic effects were related to the lymphodepleting chemotherapy regimen and included lymphopenia, neutropenia, and thrombocytopenia (21 [100%] patients for each toxicity); anaemia (14 [67%] patients); and infection (six [29%] patients). There was one treatment-related death secondary to sepsis-induced multiorgan failure.

INTERPRETATION

To our knowledge, this is the first report describing adoptive transfer of autologous TILs to mediate objective tumour regression in patients with metastatic uveal melanoma. These initial results challenge the belief that metastatic uveal melanoma is immunotherapy resistant and support the further investigation of immune-based therapies for this cancer. Refinement of this T-cell therapy is crucial to improve the frequency of clinical responses and the general applicability of this treatment modality.

FUNDING

Intramural Research Program of the National Institutes of Health, National Cancer Institute, Center for Cancer Research.

Characterization of an Immunogenic Mutation in a Patient with Metastatic Triple-Negative Breast Cancer

Purpose: The administration of autologous tumor-infiltrating lymphocytes (TILs) can mediate durable tumor regressions in patients with melanoma likely based on the recognition of immunogenic somatic mutations expressed by the cancer. There are limited data regarding the immunogenicity of mutations in breast cancer. We sought to identify immunogenic nonsynonymous mutations in a patient with triple-negative breast cancer (TNBC) to identify and isolate mutation-reactive TILs for possible use in adoptive cell transfer.Experimental Design: A TNBC metastasis was resected for TIL generation and whole-exome sequencing. Tandem minigenes or long 25-mer peptides encoding selected mutations were electroporated or pulsed onto autologous antigen-presenting cells, and reactivity of TIL was screened by upregulation of CD137 and IFNγ ELISPOT. The nature of the T-cell response against a unique nonsynonymous mutation was characterized.Results: We identified 72 nonsynonymous mutations from the tumor of a patient with TNBC. CD4⁺ and HLA-DRB1*1501-restricted TILs isolated from this tumor recognized a single mutation in RBPJ (recombination signal binding protein for immunoglobulin kappa J region). Analysis of 16 metastatic sites revealed that the mutation was ubiquitously present in all samples.Conclusions: Breast cancers can express naturally processed and presented unique nonsynonymous mutations that are recognized by a patient's immune system. TILs recognizing these immunogenic mutations can be isolated from a patient's tumor, suggesting that adoptive cell transfer of mutation-reactive TILs could be a viable treatment option for patients with breast cancer. Clin Cancer Res; 23(15); 4347-53. ©2017 AACR.

Lymphoma Remissions Caused by Anti-CD19 Chimeric Antigen Receptor T Cells Are Associated With High Serum Interleukin-15 Levels

Purpose T cells genetically modified to express chimeric antigen receptors (CARs) targeting CD19 (CAR-19) have potent activity against acute lymphoblastic leukemia, but fewer results supporting treatment of lymphoma with CAR-19 T cells have been published. Patients with lymphoma that is chemotherapy refractory or relapsed after autologous stem-cell transplantation have a grim prognosis, and new treatments for these patients are clearly needed. Chemotherapy administered before adoptive T-cell transfer has been shown to enhance the antimalignancy activity of adoptively transferred T cells. Patients and Methods We treated 22 patients with advanced-stage lymphoma in a clinical trial of CAR-19 T cells preceded by low-dose chemotherapy. Nineteen patients had diffuse large B-cell lymphoma, two patients had follicular lymphoma, and one patient had mantle cell lymphoma. Patients received a single dose of CAR-19 T cells 2 days after a low-dose chemotherapy conditioning regimen of cyclophosphamide plus fludarabine. Results The overall remission rate was 73% with 55% complete remissions and 18% partial remissions. Eleven of 12 complete remissions are ongoing. Fifty-five percent of patients had grade 3 or 4 neurologic toxicities that completely resolved. The low-dose chemotherapy conditioning regimen depleted blood lymphocytes and increased serum interleukin-15 (IL-15). Patients who achieved a remission had a median peak blood CAR⁺ cell level of 98/μL and those who did not achieve a remission had a median peak blood CAR⁺ cell level of 15/μL ( P = .027). High serum IL-15 levels were associated with high peak blood CAR⁺ cell levels ( P = .001) and remissions of lymphoma ( P < .001). Conclusion CAR-19 T cells preceded by low-dose chemotherapy induced remission of advanced-stage lymphoma, and high serum IL-15 levels were associated with the effectiveness of this treatment regimen. CAR-19 T cells will likely become an important treatment for patients with relapsed lymphoma.

Abstract P2-04-02: Recognition of autologous neoantigens by tumor infiltrating lymphocytes derived from breast cancer metastases

Background & Translational Relevance: Adoptive transfer of tumor infiltrating lymphocytes (TIL) can effect long-term durable regression in patients with metastatic melanoma but has not been widely tested in common epithelial cancers. When examining the TIL of successfully treated patients with melanoma, a heterogeneous T cell population can be identified with reactivity against melanoma differentiation antigens, cancer germline antigens, and personalized non-synonymous somatic mutations. Common epithelial cancers, including breast cancer, express far fewer somatic mutations than melanoma, however, a patient with metastatic cholangiocarcinoma was treated with autologous CD4+ TIL enriched for neoantigen specificity and has experienced an ongoing partial response (&gt;2 years). It is known that the presence of TIL on pathologic examination of triple-negative breast cancers is a positive prognostic marker for disease-free survival and overall survival. The identification of enriched populations of neoantigen-specific TIL could form the basis for personalized cell therapy for patients with metastatic breast cancer. This pilot study investigates the ability to grow TIL from breast cancer metastases, to identify personalized non-synonymous somatic mutations and potential neoantigens, and to adoptively transfer TIL into patients with breast cancer.

Methods: Eligible patients were evaluated and treated under IRB-approved protocols for tissue procurement, genomic testing, and adoptive cell transfer. Portions of resected tumors were placed in culture under standard TIL conditions. DNA was extracted from tumor and matched normal peripheral blood samples for whole exome sequencing (WES). Non-synonymous somatic mutations were identified and tested for potential immunogenicity.

Results: Nine patients have undergone surgical resection in this ongoing pilot study, and TIL was successfully grown from the tumors of all patients. All were primarily CD3+ (median 79%) with a small population of natural killer cells. Of the CD3+ cells, 7 of 9 patients had a predominantly CD4+ population (median CD4:CD8 ratio 2.2, range 0.4-5.8). With the exception of a single patient with inflammatory breast cancer, tumor purity allowed for WES of the tumors of eight patients, and non-synonymous somatic mutations were identified as potential neoantigens (median 96.5, range 71-148). Autologous T cell reactivity has been identified against tumor-specific mutations in 4 of 6 patients studied. The TIL of one patient demonstrated in vitro reactivity to a mutated form of RBPJ, a DNA-binding protein involved in Notch1 signaling. In addition, specimens obtained from this patient at autopsy contained the specific RBPJ mutation (RBPJ c.A611T) in every sampled tumor (n=16). Other patient-specific neoantigens identified by autologous reactivity include SLC3A2, KIAA0368, and a mutated TCRBV domain.

Conclusions: Tumor-infiltrating lymphocytes derived from metastatic breast cancer can react to tumor-specific non-synonymous somatic mutations in vitro. TIL grown from breast cancers are predominantly CD4+ and can form the basis of an adoptive cell transfer experimental approach to patients with metastatic breast cancer.

Citation Format: Goff SL, Zacharakis N, Assadipour Y, Prickett T, Gartner J, Somerville R, Black MA, Xu H, Chinnasamy H, Kriley I, Lu L, Statler M, Wunderlich J, Robbins PF, Rosenberg SA, Feldman SA. Recognition of autologous neoantigens by tumor infiltrating lymphocytes derived from breast cancer metastases [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 P2-04-02.

Metastasectomy Following Immunotherapy with Adoptive Cell Transfer for Patients with Advanced Melanoma

Background

Immunotherapeutic treatment strategies including adoptive cell transfer (ACT) for metastatic melanoma are capable of mediating complete and durable responses, as well as partial responses and prolonged disease stabilization. Unfortunately, many patients ultimately develop progressive disease. The role of salvage metastasectomy in managing these patients has not been evaluated.

Methods

Records of patients with metastatic melanoma treated with ACT at a single institution between 2000 and 2014 were reviewed. Patients with an objective response by RECIST criteria or disease stabilization of at least 6 months and who subsequently developed progressive melanoma and were managed with metastasectomy as the next therapeutic strategy were studied for progression-free survival (PFS) and overall survival (OS). Five additional clinical parameters were also reviewed for association with outcomes.

Results

Of 115 patients treated with ACT who met our response criteria and then developed progressive disease, 26 (23%) had surgery. There were no mortalities related to surgical intervention. Median follow-up after surgery was 62 months. Median PFS after surgery was 11 months and five-year OS was 57%. The development of a new site of metastasis after ACT was associated with poor PFS and OS.

Conclusions

Surgery after immunotherapy is safe. Long PFS and OS can be achieved by metastasectomy in selected patients with progressive melanoma following treatment with ACT. Clinical variables important for patient selection for metastasectomy after immunotherapy remain largely undefined. Improvements in immunotherapeutic treatment strategies may increase the role of surgery for patients with advanced disease.

Anti-CD19 chimeric antigen receptor T cells preceded by low-dose chemotherapy to induce remissions of advanced lymphoma

LBA3010

Background: T cells genetically-modified to express chimeric antigen receptors (CARs) targeting CD19 have potent activity against a variety of B-cell malignancies. Chemotherapy is administered prior to CAR T cells because depletion of recipient leukocytes enhances the anti-malignancy efficacy of adoptively-transferred T cells; an increase in serum interleukin (IL)-15 is one mechanism for this enhancement. Previously, we (Kochenderfer et al. Journal of Clinical Oncology, 2015) and others have reported patients treated with high-dose chemotherapy prior to anti-CD19 CAR T-cell infusions. This report describes treatment of 22 patients with low-dose conditioning chemotherapy followed by infusion of anti-CD19 CAR T-cells. Methods: Eighteen of 22 treated patients received 300 mg/m2 of cyclophosphamide (cy) daily for 3 days; 4 patients received 500 mg/m2 of cy on the same schedule. All patients received fludarabine 30 mg/m2daily for 3 days on the same days as cy. Patients received a single dose of CAR T cells 2 days after completion of chemotherapy. Blood CAR T cells and serum cytokines were analyzed in all patients. Results: Nineteen patients with various subtypes of diffuse large B-cell lymphoma (DLBCL) had the following responses: 8 CR, 5 PR, 2 SD, and 4 PD. One patient with mantle cell lymphoma obtained a CR. Two patients with follicular lymphoma both obtained CRs. Durations of response currently range from 1 to 20 months; 10 remissions are ongoing. All but 4 patients had either chemotherapy-refractory lymphoma or lymphoma that had relapsed after autologous stem cell transplant. The most prominent toxicities were various neurological toxicities. Other toxicities included fever and hypotension. The median peak blood CAR+ cell level was 47/μL (range 4-1217/μL). Patients obtaining CRs or PRs had higher peak blood CAR+ cell levels than patients experiencing SD or PD. The mean serum IL-15 level was 4 pg/mL before the conditioning chemotherapy and 32 pg/mL after chemotherapy (P < 0.0001). Conclusions: Anti-CD19 CAR T cells can induce remissions of advanced B-cell lymphoma when administered after low-dose chemotherapy. In the near future, CAR T cells will likely be a standard therapy for lymphoma. Clinical trial information: NCT00924326.

Randomized, Prospective Evaluation Comparing Intensity of Lymphodepletion Before Adoptive Transfer of Tumor-Infiltrating Lymphocytes for Patients With Metastatic Melanoma

PURPOSE

Adoptive cell transfer, the infusion of large numbers of activated autologous lymphocytes, can mediate objective tumor regression in a majority of patients with metastatic melanoma (52 of 93; 56%). Addition and intensification of total body irradiation (TBI) to the preparative lymphodepleting chemotherapy regimen in sequential trials improved objective partial and complete response (CR) rates. Here, we evaluated the importance of adding TBI to the adoptive transfer of tumor-infiltrating lymphocytes (TIL) in a randomized fashion.

PATIENTS AND METHODS

A total of 101 patients with metastatic melanoma, including 76 patients with M1c disease, were randomly assigned to receive nonmyeloablative chemotherapy with or without 1,200 cGy TBI before transfer of tumor-infiltrating lymphcytes. Primary end points were CR rate (as defined by Response Evaluation Criteria in Solid Tumors v1.0) and overall survival (OS). Clinical and laboratory data were analyzed for correlates of response.

RESULTS

CR rates were 24% in both groups (12 of 50 v 12 of 51), and OS was also similar (median OS, 38.2 v 36.6 months; hazard ratio, 1.11; 95% CI, 0.65 to 1.91; P = .71). Thrombotic microangiopathy was an adverse event unique to the TBI arm and occurred in 13 of 48 treated patients. With a median potential follow-up of 40.9 months, only one of 24 patients who achieved a CR recurred.

CONCLUSION

Adoptive cell transfer can mediate durable complete regressions in 24% of patients with metastatic melanoma, with median survival > 3 years. Results were similar using chemotherapy preparative regimens with or without addition of TBI.

Abstract OT1-01-03: Adoptive cell transfer (ACT) using tumor infiltrating lymphocytes to target neoantigens in patients with metastatic breast cancer

Background: Adoptive transfer of tumor infiltrating lymphocytes (TIL) can cure patients with metastatic melanoma, likely based on the recognition of mutated neoantigens (Robbins et al Nature Medicine 2013). Although immunogenic cancer antigens have been found in gastrointestinal cancers (Tran et al Science 2014), this has not been widely studied in patients with breast cancer. The presence of TIL on pathologic examination of triple-negative breast cancers is a positive prognostic marker for disease-free survival and overall survival. This pilot study investigates the ability to grow TIL from breast cancer metastases, to identify personalized non-synonymous mutations and potential neoantigens, and to adoptively transfer TIL into patients with breast cancer.

Trial Design: This is a single-arm, non-randomized pilot study of adoptive immunotherapy in patients with metastatic epithelial cancers with a cohort designated for those patients with breast cancer. Once screened for eligibility, patients undergo metastectomy to obtain tissue for culture of TIL and extensive in vitro studies will be performed to identify TIL cultures reactive to neoantigens. Once robust TIL have been identified, the patient is admitted to the National Institutes of Health Clinical Center for conditioning chemotherapy, TIL infusion and interleukin-2. Treatment and recovery generally entails about three weeks as an inpatient.

Eligibility Criteria: Patients between the ages of 18 and 70 with metastatic breast cancer who have measurable metastatic disease with at least one lesion resectable with minimal morbidity. Patients must be refractory to standard systemic therapy and must have shown progression on at least two lines of chemotherapy prior to infusion of TIL. Patients must be of good performance status (ECOG 0-1) and have three or fewer brain metastases. In addition, patients must meet common hematologic and chemistry lab criteria. Given the nature of immunotherapy and the rigorous treatment, patients are ineligible for the following reasons: dependence on steroids, cardiac dysfunction, active infection, active major medical illness of the respiratory, cardiovascular or immune system.

Specific Aims: The aims are both clinical and research oriented. Of greatest interest is to determine the ability of autologous TIL to mediate tumor regression in patients with metastatic breast cancer. We will also be examining the phenotypic and functional characteristics of TIL derived from breast cancer metastases. We will be attempting to identify non-synonymous immunogenic mutations within resected tumors.

Statistical Methods and Trial Accrual: Twenty-one patients will be initially enrolled in the treatment phase of this cohort to assess toxicity and tumor responses. If two or more of the first 21 patients per groups shows a clinical response (PR or CR), accrual will continue to 41 patients, targeting a 20% goal for objective response. We have currently enrolled three patients on the screening phase of this trial and one patient on the treatment phase.

Contact Information: National Cancer Institute Surgery Branch Immunotherapy Referral Office, irc@nih.gov, (301) 451-1929, (866) 820-4505 Toll Free. ClinicalTrials.gov: NCT01174121.

Citation Format: Goff SL, Feldman SA, Somerville R, Rosenberg SA. Adoptive cell transfer (ACT) using tumor infiltrating lymphocytes to target neoantigens in patients with metastatic breast cancer. [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 OT1-01-03.

Neoadjuvant therapy for non-metastatic pancreatic ductal adenocarcinoma

Treatment of pancreatic cancer is increasingly multimodal, with patients receiving chemotherapy, radiation, and surgical extirpation in hope of long-term cure. There is ongoing debate over the timing, sequence, and necessity of these treatments as they pertain to the spectrum of local-regional disease. Current guidelines support a neoadjuvant strategy in patients with locally advanced and borderline resectable disease. Although there is currently no high-level evidence to recommend neoadjuvant therapy for all patients, there are data to suggest that wider application of neoadjuvant therapy may be beneficial. Random-assignment prospective trials are ongoing. In this review we examine the literature addressing a neoadjuvant approach to potentially resectable, borderline resectable, and locally advanced pancreatic cancer and highlight the outcomes of preoperative emergence of latent metastatic disease, attempted resection rates, margin negative resection rates, and pathologic response to treatment.

Small bowel carcinoid: Location isn’t everything!

AIM: To investigate the prognostic significance of the primary site of disease for small bowel carcinoid (SBC) using a population-based analysis.

METHODS: The Surveillance, Epidemiology and End Results (SEER) database was queried for histologically confirmed SBC between the years 1988 and 2009. Overall survival (OS) and disease-specific survival (DSS) were analyzed using the Kaplan-Meier method and compared using Log rank testing. Log rank and multivariate Cox regression analyses were used to identify predictors of survival using age, year of diagnosis, race, gender, tumor histology/size/location, tumor-node-metastasis stage, number of lymph nodes (LNs) examined and percent of LNs with metastases.

RESULTS: Of the 3763 patients, 51.2% were male with a mean age of 62.13 years. Median follow-up was 50 mo. The 10-year OS and DSS for duodenal primaries were significantly better when compared to jejunal and ileal primaries (P = 0.02 and < 0.0001, respectively). On multivariate Cox regression analysis, after adjusting for multiple factors, primary site location was not a significant predictor of survival (P = 0.752 for OS and P = 0.966 DSS) while age, number of primaries, number of LNs examined, T-stage and M-stage were independent predictors of survival.

CONCLUSION: This 21-year, population-based study of SBC challenges the concept that location of the primary lesion alone is a significant predictor of survival.

A simple and effective method to generate lentiviral vectors for ex vivo gene delivery to mature human peripheral blood lymphocytes

Human ex vivo gene therapy protocols have been used successfully to treat a variety of genetic disorders, infectious diseases, and cancer. Murine oncoretroviruses (specifically, gammaretroviruses) have served as the primary gene delivery vehicles for these trials. However, in some cases, such vectors have been associated with insertional mutagenesis. As a result, alternative vector platforms such as lentiviral vectors (LVVs) are being developed. LVVs may provide advantages compared with gammaretroviral vectors, including the ability to transduce large numbers of nondividing cells, resistance to gene silencing, and a potentially safer integration profile. The aim of this study was to develop a simplified process for the rapid production of clinical-grade LVVs. To that end, we used a self-inactivating bicistronic LVV encoding an MART (melanoma antigen recognized by T cells)-1-reactive T cell receptor containing oPRE, an optimized and truncated version of woodchuck hepatitis virus posttranslational regulatory element (wPRE). Using our simplified clinical production process, 293T cells were transiently transfected in roller bottles. The LVV supernatant was collected, treated with Benzonase, and clarified by modified step filtration. LVV produced in this manner exhibited titers and a biosafety profile similar to those of cGMP (current Good Manufacturing Practices) LVVs previously manufactured at the Indiana University Vector Production Facility in support of a phase I/II clinical trial. We describe a simple, efficient, and low-cost method for the production of clinical-grade LVV for ex vivo gene therapy protocols.

Rapid production of clinical-grade gammaretroviral vectors in expanded surface roller bottles using a "modified" step-filtration process for clearance of packaging cells

Production of clinical-grade gammaretroviral vectors for ex vivo gene delivery requires a scalable process that can rapidly generate large amounts of vector supernatant, clear large numbers of residual packaging cells with minimal decreases in vector titer, and satisfy all current regulatory guidelines regarding product biosafety. To that end, we have developed a simplified method that is compliant with current good manufacturing practices for the production of clinical-grade gammaretroviral vectors in a clinical research environment. We validated a large-scale production platform utilizing 1,700-cm(2) expanded surface roller bottles and a "modified" step-filtration process consisting of a 40/150-μm dual-screen filter for aggregate removal followed by a Sepacell 500II leukocyte reduction filter for removal of residual packaging cells. This clarification process can clear at least 2 × 10(9) viable producer cells using a single filter set-up without any significant loss of titer post-filtration. This platform typically generates 18 liters of vector supernatant to support small-scale clinical trials, but can easily be scaled up to 70 liters during a single manufacturing run. To date, this platform has generated five clinical-grade gammaretroviral vector products, four of which are now being used in adoptive cell therapy clinical trials for the treatment of a variety of solid cancers.

Enhanced receptor expression and in vitro effector function of a murine-human hybrid MART-1-reactive T cell receptor following a rapid expansion

Peripheral blood lymphocytes (PBL) genetically modified to express T cell receptors (TCR) specific to known melanoma antigens, such as melanoma antigen recognized by T cells-1 (MART-1), and gp100 can elicit objective tumor regression when administered to patients with metastatic melanoma. It has also been demonstrated that modifications within the constant regions of a fully human TCR can enhance surface expression and stability without altering antigen specificity. In this study, we evaluated the substitution of murine constant regions for their human counterpart within the DMF5 MART-1-specific TCR. Unlike previous studies, all modified TCRs were inserted into retroviral vectors and analyzed for expression and function following a clinical transduction protocol. PBL were transduced with retroviral supernatant generated from stable packaging lines encoding melanoma-specific TCRs. This protocol resulted in high levels of antigen-specific T cells without the need for additional peptide stimulation and selection. Both the human and murinized TCR efficiently transduced PBL; however, the murinized TCR exhibited significantly higher tetramer binding, mean fluorescence intensity, as well as, increased in vitro effector function following our clinical transduction and expansion protocol. Additional TCR modifications including insertion of a second disulfide bond or the linker modifications evaluated herein did not significantly enhance TCR expression or subsequent in vitro effector function. We conclude that the substitution of a human constant region with a murine constant region was sufficient to increase receptor expression and tetramer binding as well as antitumor activity of the DMF5 TCR and could be a tool to augment other antigen-specific TCR.

Postmarketing experience with topiramate and cognition

Ideal antiepileptic drugs (AEDs) are designed to stop seizures with limited central nervous system (CNS) side effects. However, CNS-related treatment-emergent adverse events (TEAEs) often occur in patients receiving AEDs. Topiramate (TPM) is an AED proven to be safe and effective as adjunctive treatment for epilepsy patients with partial seizures. Double-blind, placebo-controlled, multicenter trials demonstrated potential effects on cognition. The P.A.D.S. (post-marketing antiepileptic drug survey) group, a cooperative group of 14 epilepsy centers that collaborate on obtaining data about new AEDs and devices, prospectively collected standardized data forms before and during treatment with TPM for epilepsy, and analyzed the postmarketing experience of CNS TEAEs with TPM. Our results from 701 treated patients show that cognitive complaints were the most common reason to discontinue TPM. The presence of complaints did have predictive value if the patient would discontinue TPM, although was not specific as to when discontinuation would occur. The spectrum of complaints in our open-label prospective multicenter postmarketing study was similar to those observed in controlled clinical trials. We were unable to demonstrate a specific population, dose titration, or concomitant AED that was at risk to discontinue treatment. We conclude that most patients treated with TPM will continue therapy beyond 6 months. Cognitive complaints and not efficacy reflect the primary reason for discontinuing therapy. Psychomotor slowing was the most common complaint, yet most patients elect to continue treatment, with "better" or "much better" ratings of both seizure and global improvement during treatment.