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`Author manuscript
`Clin Cancer Res. Author manuscript; available in PMC 2016 July 15.
`
`Published in final edited form as:
`Clin Cancer Res. 2015 July 15; 21(14): 3149–3159. doi:10.1158/1078-0432.CCR-14-1421.
`
`Phase I Hepatic Immunotherapy for Metastases study of intra-
`arterial chimeric antigen receptor modified T cell therapy for
`CEA+ liver metastases
`
`Steven C. Katz1, Rachel A. Burga1, Elise McCormack2, Li Juan Wang3, Wesley Mooring3,
`Gary Point1, Pranay D. Khare4, Mitchell Thorn1, Qiangzhong Ma2, Brian F. Stainken5, Earle
`O. Assanah5, Robin Davies4, N. Joseph Espat1, and Richard P. Junghans2
`
`1Roger Williams Medical Center, Department of Surgery, Providence, RI/Boston University
`School of Medicine, Boston, MA 2Roger Williams Medical Center, Department of Medicine,
`Providence, RI/Boston University School of Medicine, Boston, MA 3Department of Pathology,
`Roger Williams Medical Center, Providence, Rhode Island 4Roger Williams Medical Center, GMP
`Core Facility and Clinical Protocol Office, Providence, RI 5Roger Williams Medical Center,
`Department of Radiology, Providence, RI/Boston University School of Medicine, Boston, MA
`
`Abstract
`
`Purpose—Chimeric antigen receptor modified T cells (CAR-T) have demonstrated encouraging
`results in early-phase clinical trials. Successful adaptation of CAR-T technology for CEA-
`expressing adenocarcinoma liver metastases (LM), a major cause of death in patients with
`gastrointestinal cancers, has yet to be achieved. We sought to test intrahepatic delivery of anti-
`CEA CAR-T through percutaneous hepatic artery infusions (HAI).
`
`Experimental Design—We conducted a phase I trial to test HAI of CAR-T in patients with
`CEA+ LM. Six patients completed the protocol, and 3 received anti-CEA CAR-T HAIs alone in
`dose-escalation fashion (108, 109, and 1010 cells). We treated an additional 3 patients with the
`maximum planned CAR-T HAI dose (1010 cells X 3) along with systemic IL2 support.
`
`Results—Four patients had more than 10 LM and patients received a mean of 2.5 lines of
`conventional systemic therapy prior to enrollment. No patient suffered a grade 3 or 4 adverse
`event related to the CAR-T HAIs. One patient remains alive with stable disease at 23 months
`following CAR-T HAI and 5 patients died of progressive disease. Among the patients in the
`cohort that received systemic IL2 support, CEA levels decreased 37% (range 19–48%) from
`baseline. Biopsies demonstrated an increase in LM necrosis or fibrosis in 4 of 6 patients. Elevated
`serum IFNγ levels correlated with IL2 administration and CEA decreases.
`
`Conclusions—We have demonstrated the safety of anti-CEA CAR-T HAIs with encouraging
`signals of clinical activity in a heavily pre-treated population with large tumor burdens. Further
`clinical testing of CAR-T HAIs for LM is warranted.
`
`Correspondence: Richard P. Junghans, PhD, MD, Department of Medicine, Roger Williams Medical Center, 825 Chalkstone Avenue,
`Providence, RI 02908, Tel: (401) 456-2484, Fax: (401) 456-6708, rjunghans@rwmc.org.
`Conflicts of Interest: The authors have no relevant disclosures.
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`INTRODUCTION
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`Liver metastases (LM) are a significant cause of morbidity and mortality in patients with
`gastrointestinal adenocarcinoma. Tumor infiltrating lymphocyte (TIL) studies have revealed
`that host T cell responses to LM are significant correlates of survival (1–5). While those
`who mount effective immune responses to LM tend to have prolonged survival, the vast
`majority of patients succumb to their disease in the context of endogenous immune failure.
`The immunosuppressive nature of the intrahepatic milieu (6–9) may promote the
`development of LM and contribute to aggressive disease biology. Given the favorable
`effects of robust liver TIL responses and the inherent suppressive nature of the intrahepatic
`space, delivery of highly specific T cell products for the treatment of LM is a rational
`approach.
`
`T cells engineered with chimeric antigen receptors (CAR) to enable highly specific tumor
`recognition and killing have gained considerable attention (10–12). Reprogramming T cells
`with CAR genes provides an MHC-independent mechanism for docking with and lysing
`tumor cells. Such modified T cells have been alternatively termed “designer T cells”, “T-
`bodies”, or “CAR-T cells” (13–15). Carcinoembryonic antigen (CEA) is an attractive target
`for CAR-T treatment of adenocarcinoma LM given high levels of CEA expression and the
`ability to measure CEA in serum (16, 17). Upon antigen recognition, anti-CEA CAR-Ts
`proliferate, produce cytokines, and kill target cells (18). Previous clinical studies, which
`evaluated systemic delivery of anti-CEA T cells for metastatic adenocarcinoma,
`demonstrated both promise and dose limiting toxicity (19). To improve the tolerability of
`anti-CEA CAR-Ts for LM in addition to enhancing tumor killing within the liver, we
`studied a regional delivery strategy.
`
`Regional intra-arterial delivery of chemotherapy for LM has been demonstrated to yield
`superior response rates and limited systemic morbidity (20). Prior reports of regionally
`infused adoptive cell therapy products have demonstrated the safety of this approach (21–
`25). We propose that hepatic artery infusion (HAI) of anti-CEA CAR-Ts will limit
`extrahepatic toxicity while optimizing efficacy for treatment of LM. To test the safety and in
`vivo activity of anti-CEA CAR-Ts in patients with LM, we conducted the phase I Hepatic
`Immunotherapy for Metastases (HITM) trial (NCT01373047). We utilized a second-
`generation anti-CEA CAR (18), containing the CD28 co-stimulatory and CD3ζ signaling
`domains. We treated an initial cohort with CAR-T HAI intra-patient dose escalations
`without IL2 support and a second cohort that received fixed CAR-T doses with continuous
`IL2 infusions.
`
`Six patients with LM completed our protocol and we demonstrated that HAIs of anti-CEA
`CAR-Ts were well tolerated with and without IL2 infusion. We also demonstrated in vivo
`activity of CAR-T HAIs in patients with large volume LM refractory to conventional
`treatment. In addition to exploring the safety and efficacy of CAR-T HAIs, we examined
`immunologic correlates of intrahepatic and systemic responses. Our findings support testing
`of CAR-T HAIs for LM in future trials.
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`METHODS
`
`Study design
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`In this phase I study (NCT01373047, RWH 11-335-99) we treated two cohorts of three
`patients with anti-CEA CAR-T HAIs without or with systemic IL2 support (Figure 1).
`Cohort 1 was treated with CAR-T HAIs in intrapatient dose escalation fashion (108, 109, and
`1010 cells) without IL2. Those in the cohort 2 received 3 HAI of 1010 CAR-Ts in addition to
`continuous systemic IL2 infusion at 75,000 U/kg/day via an ambulatory infusion pump.
`
`Eligible patients had measurable unresectable CEA-positive LM or detectable serum CEA
`levels and failed one or more lines of conventional systemic therapy. Minimal extra-hepatic
`disease in the lungs or abdomen was permitted. No commercial sponsor was involved in the
`study. Clinical assessments were scheduled on infusion days, and on days 1, 2, 4, and 7 post-
`infusion. Liver MRI and PET examinations were performed within one month prior to the
`first infusion and then within one month following the third CAR-T HAI. The study
`radiologist (BS) graded responses according to modified RECIST (mRECIST) and immune
`related response criteria (26). Safety evaluation was performed per protocol. Severity of
`adverse events was graded using the National Cancer Institute Common Terminology
`Criteria for Adverse Events version 3.0.
`
`Human CAR-T cell production
`The 2nd generation anti-CEA scfv-CD28/CD3ζ (Tandem) chimeric antigen receptor was
`cloned into the MFG retroviral backbone as previously described (FDA BB IND 10791)
`(18). Briefly, the tandem molecule was generated by fusing the hMN14 sFv-CD8 hinge
`segment of the IgTCR (IgCEA) in the MFG retroviral backbone with a hybrid CD28/CD3ζ
`molecule. The construct was verified by sequencing. The clinical retroviral vector
`supernatant was produced using PG13 cells to generate gibbon ape leukemia virus
`pseudotyped viral particles as described (27). All clinical batches were prepared at Indiana
`University vector production facility (Indianapolis, IN) and stored at −80°C.
`
`Rhode Island Blood Center personnel performed leukapheresis at the Roger Williams
`Medical Center (RWMC, Providence, RI). Anti-CEA CAR-Ts were prepared at the RWMC
`Cell Immunotherapy and Gene Therapy (CITGT) Good Manufacturing Practice (GMP)
`Facility with standard operating procedures (SOPs) for processing, manufacturing,
`expansion, dose harvesting, labeling, storage and distribution. Briefly, patient peripheral
`blood mononuclear cells (PBMCs) were isolated from leukapheresis product using Ficoll
`(Sigma, St; Louis, MO). We then activated PBMCs for 48–72 hours in tissue culture flasks
`(BD Falcon, Franklin Lakes, NJ) containing AIM V media (Life Technologies, Grand
`Island, NY) supplemented with 5% sterile human AB serum (Valley Biomedical,
`Winchester, VA), 50 ng/mL of anti-CD3 monoclonal antibody (OKT3; Ortho Biotech,
`Horsham, PA) and 3000 U/mL of IL2 (Prometheus, San Diego, CA).
`
`Using the spinoculation method (28), 7.2 – 14.4 × 108 T cells were transduced in retronectin
`(Takara Bio Inc, Japan) coated 6-well plates in AIM V media with 5% human AB serum,
`3000 U/ mL of IL2, and protamine sulfate (MP Biomedicals) at low speed centrifugation for
`1 hour at room temperature. Three transductions were carried out over 24-hrs. After
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`transduction, cells were washed and incubated for 48–72 hours at 37°C. CAR-Ts were
`further expanded in Lifecell tissue culture bags (Baxter, Deerfield, IL) for 10–14 days.
`CAR-T growth curves and cell viability were examined periodically and cell growth media
`was replaced as required. CAR-Ts were examined by flow cytometry with fluorescently
`labeled antibodies specific for CD3 (UCHT1, Invitrogen, Frederick, MD), CD4 (SK3, BD
`Biosciences, San Jose, CA), CD8 (3B5, Invitrogen), and CAR expression (WI2 antibody,
`Immunomedics, Norris Plains, NJ). The WI2 antibody was prepared as an APC conjugate
`(WI2-APC; Molecular Probes). Flow cytometry was performed on a CyAn (Beckman
`Coulter, Brea, CA) or LSR-II (BD Biosciences, San Jose, CA) machine. In vitro activity of
`patient products was measured by bioluminescence cytotoxicity assay. Luciferase-
`expressing CEA+ tumor cells were mixed with anti-CEA CAR-T at various ratios in 96-well
`round bottom plates and loss of bioluminescence from each well measured (29).
`
`We prepared clinical doses using a Fenwal cell harvester system (Baxter, Deerfield, IL) in
`freezing media containing PlasmaLyte (Baxter), 20% human bovine albumin (Valley
`Biomedicals), 10% DMSO (Bioniche Pharma, Lake Forrest, IL) and IL2. Bacterial and
`fungal cultures were monitored for 14 and 28 days respectively. We performed assays for
`endotoxin with LAL Endotoxin assay kits (Lonza, Walkersville, MD). The clinical dose was
`stored in liquid nitrogen and thawed immediately prior to infusion.
`
`Product delivery
`
`At baseline, a mapping angiogram was performed via a common femoral artery approach.
`The gastroduodenal and right gastric arteries, in addition to other potential sources of
`extrahepatic perfusion, were embolized with microcoils. For CAR-T infusions, the same
`arterial access procedure was carried out and the cells were hand injected via a 60cc syringe
`at a rate of <2cc/second with a total volume of 100cc. Angiography with calibrated contrast
`rate was performed after the first 50cc and at completion of the CAR-T infusion to confirm
`preserved arterial flow. Infusions were delivered into the proper hepatic artery when
`possible. In cases of aberrant hepatic arterial anatomy, where either the right or left hepatic
`artery did not arise from the proper hepatic artery, the dose was split based upon lobar
`volume calculations. In such cases, split doses were delivered separately into the right and
`left hepatic arteries to ensure proportionate CAR-T delivery to both lobes.
`
`Correlative studies
`
`Normal liver and LM core needle (16-gauge) biopsies were obtained under sonographic
`guidance at baseline and at the time of the third CAR-T HAI. Three cores were obtained for
`normal liver and LM, with each confirmed by cytology. For each case, 4–5 μm sections
`were stained with H&E and additional unstained slides were stained with anti-CEA antibody
`(TF 3H8-1, Ventana, Tucson, AZ). All immunohistochemical stains were performed on the
`Ventana Medical System at Our Lady of Fatima Hospital (Providence, RI). All slides were
`reviewed in blinded fashion and graded for necrosis and fibrosis. Fibrosis was scored as
`follows: 0% = grade 0; 5–10% = grade 1; 11–50% = grade 2; >50% = grade 3. Necrosis was
`scored as follows: 0% = grade 0; 0–10% = grade 1; 11–50% = grade 2; >50% = grade 3.
`Flow cytometry was performed on fresh biopsy tissue for CAR-T cells and peripheral blood
`as described above.
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`We measured serum IFNγ levels in all patients by ELISA (EBioscience, San Diego, CA).
`Samples were purified with the Purelink DNA Isolation Kit (Life Technologies, Grand
`Island, NY) according to the manufacturer’s instructions. Patient serum was screened for
`anti-CAR antibodies one month after treatment by flow cytometry. We mixed CAR+ or
`CAR- Jurkat cells with 100ul of 1:1 diluted patient serum and then stained with secondary
`goat anti-human immunoglobulin.
`
`CAR DNA was measured from patient whole blood genomic DNA by qPCR performed at
`the Boston University Analytical Core Facility. SYBR Green technology was used and CAR
`positive samples were identified using 100uM 28F2 forward (5′-
`GCAAGCATTACCAGCCCTAT-3′) and zr2 reverse (5′-GTTCTGGCCCTGCTGGTA-3′)
`primers (custom, Sigma Aldrich, St. Louis, MO). Plasmid DNA containing the CAR gene
`was used as a positive control qPCR. Additional primers were used to amplify CD3,
`GAPDH, and RPL13A (Bio-Rad, Hercules, CA). Raw cycle threshold (Ct) values were
`normalized to the average of the two reference genes (RPL13A and GAPDH) and we used
`the DeltaDelta Ct method to analyze the results. Wet-lab validated and MIQE-compliant
`primers were purchased from BioRad (Hercules, CA).
`
`RESULTS
`
`Study design and patient characteristics
`
`We enrolled eight patients with unresectable CEA+ adenocarcinoma LM who progressed on
`an average of 2.5 (range 2–4) lines of conventional systemic therapy (Table 1). Six patients
`completed the protocol (Figure 1A), one patient withdrew due to an unrelated infection prior
`to treatment, and another patient withdrew due to extrahepatic disease progression prior to
`his third CAR-T HAI. Of the patients that completed the protocol, 4 were male and 2 were
`female. Five patients had stage IV colorectal carcinoma and one patient had pancreatobiliary
`ampullary carcinoma. The average age was 57 (range, 51–66). Patients presented with
`substantial disease burdens, with the average size of the largest LM being 8.4 cm (range,
`1.7–14.4) and five patients having more than 10 LM. The mean CEA level upon enrollment
`was 807 ng/ml (range, 2–3265). Five of eight patients had synchronous colorectal LM and
`the mean disease-free interval was 27.3 months (range, 9 to 37) for patients with
`metachronous LM. All further analyses include only the six patients who completed the
`study.
`
`CAR-T cell product assessment
`
`The leukapheresis product from each patient was analyzed by flow cytometry prior to and
`following transduction with anti-CEA CAR construct. For all patients, the mean percentage
`of CD3+ cells following leukapheresis was 55% (range, 12.0–82.0) and increased to 91%
`(range, 72–97) following activation and transduction (Figure 1B). The mean CD4:CD8 ratio
`was 2.4 (range, 1.4–4.7) in the leukapheresis samples and 0.8 (0.2–2.2) in the final products
`(not shown). The transduction efficiency (CAR+) ranged from 10% to 64%, with a mean of
`45% (Figure 1B). Negligible FoxP3 staining was detected among CAR+ T cells prior to
`infusion (not shown). Cells in the final products were 85% viable prior to infusion (range,
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`71–95). In vitro cytotoxicity assays confirmed that patient products specifically lysed CEA+
`target cells (Supplemental Figure 1).
`
`CAR-T cell trafficking following regional infusion
`
`Safety data
`
`We obtained CT guided percutaneous biopsies to sample LM and normal liver prior to the
`first CAR-T HAI and at the time of the final HAI. The proportions of CAR-T (CAR+/total
`lymphocyte%) in LM biopsy, normal liver biopsy, and peripheral blood samples were
`determined by flow cytometry. Samples from patient # 7 demonstrated that 0.8% of normal
`liver mononuclear cells were CAR+ following HAI of CAR-T and 6.6% of intratumoral
`mononuclear cells were CAR+ (Figure 1C). We confirmed that that CAR+ cells in the post-
`infusion LM biopsy specimen were CD3+. CAR-T population data in peripheral blood,
`normal liver, and LM are shown for all patients (Supplemental Figure 2, Figure 1D). CAR-
`Ts were more abundant in the LM compared to normal liver in 5 of 6 patients. In patient # 5,
`CAR-T were found to comprise 2.0% of LM mononuclear cells in a sample obtained during
`a microwave ablation procedure 12 weeks following his final CAR-T infusion (not shown).
`In 4 patients, CAR-T were not detectable in peripheral blood but were transiently present in
`P#7 and P#8 at the time of the final infusion, and the levels dropped below detection 3 days
`later. We also performed qPCR on peripheral blood samples taken at day 2 following the
`final infusion; only patient 7 had a measurable increase (1.1-fold) in CAR DNA relative to
`baseline (not shown).
`
`Anti-CAR antibodies were not detected in patient sera one month following CAR-T
`infusion. This was confirmed by screening sera against CAR+ and CAR− target cells and
`staining for anti-human Ig on the CAR+ cells as described in the methods section.
`
`Adverse events (AE) of any grade attributable to any cause were observed in all patients
`who completed the trial (Table 2). The dose in cohort 1 reached the planned maximal HAI
`CAR-T infusion level at 1010 cells. No CAR-T dose reductions were required in cohort 1
`and therefore, all patients in cohort 2 received 3 doses at the 1010 level with IL2 support.
`There were no grade 4 or 5 adverse events. Febrile AEs were observed in 4 patients. Patient
`# 7 experienced grade 3 fever and tachycardia, with a temperature peak of 104°F. The fever
`and tachycardia resolved in patient # 7 after a 50% dose reduction in her systemic IL2
`infusion. Of note, patient # 7 also experienced an increase in her peripheral eosinophil count
`with a peak of 20% and absolute count of 3,740/ml. Given the reported association between
`IL2 infusion and cardiac thrombosis with other features of Loeffler’s syndrome (30), we
`obtained an echocardiogram and electrocardiogram which were normal. The eosinophil
`count returned to normal limits without specific intervention.
`
`Normal liver parenchyma and biliary structures were well preserved following CAR-T
`HAIs. Biopsies from normal liver did not demonstrate increased levels of inflammation or
`fibrosis following CAR-T HAI whether or not systemic IL2 was administered (Figure 2A).
`While all patients experienced transient elevations of alkaline phosphatase (alk phos), total
`bilirubin, and aspartate aminotransferase levels (AST), only patient # 1 experienced grade 3
`elevations and the majority of values did not deviate significantly from baseline levels
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`(Figure 2B). Portal pressures and liver synthetic function were not adversely affected by the
`CAR-T HAIs, as reflected by no patient becoming thrombocytopenic (Figure 2C) or
`coagulopathic (Figure 2D).
`
`Clinical activity
`
`At last follow-up, 5 of the 6 heavily pre-treated patients who completed the trial died due to
`disease progression (Table 3). MRI and PET scans were performed in 5 of 6 patients at
`baseline and 2–4 weeks following the third CAR-T HAI. Patient # 8 did not obtain final
`imaging following a return to his native country and ultimately died of disease progression.
`All patients except # 5 were determined to have radiographic disease progression. Patient #
`5 was found to have stable disease by MRI and PET (Supplemental Figure 3A, arrow).
`Patient # 7 developed new lesions and demonstrated an increase in size of some pre-existing
`lesions, while other lesions decreased in size. The lesion in the posterior sector of patient # 7
`that decreased in size on MRI was not visible on PET (Supplemental Figure 3B). More
`medial disease that was decreased in size on MRI was noted to become hypometabolic on
`the post-infusion PET for patient # 7.
`
`As we anticipated limited utility for short follow-up conventional imaging following
`infusion of CAR-T, we measured serum CEA levels at multiple time points following each
`of the three HAIs for each patient. Among the patients in cohort 1, transient decreases in
`serum CEA were demonstrated in two patients following each CAR-T HAI (Figure 3A).
`CEA kinetics were closely paralleled by changes in serum CA19-9 levels (not shown).
`Patient # 4, who presented with hepatobiliary subtype ampullary carcinoma, was the only
`patient without a CEA decrease at any point during the trial and he also had the shortest
`survival time.
`
`The patients in cohort 2 who received systemic IL2 along with anti-CEA CAR-T had more
`favorable CEA responses to treatment. As each of the three patients in cohort 2 required an
`IL2 interruption or dose reduction, which would likely impact CAR-T function, we
`compared CEA levels at baseline with the time point just prior to IL2 dose change. When
`using these time points, all three patients in cohort 2 had decreases in serum CEA
`concentrations (Figure 3A and Table 3). Patients # 7 and # 8 had a 48% and 43% decrease in
`serum CEA concentrations, respectively, prior to IL2 dose interruption or reduction. The
`mean overall survival time for the 6 patients who completed the trial was 30 weeks with a
`median of 15 weeks (range, 8–102). Patient # 5 is alive with disease at 23 months (102
`weeks) following his final CAR-T HAI. Following completion of the HITM trial, patient # 5
`was determined to have stable disease and we performed a microwave ablation of residual
`unresectable tumor (Supplemental Figure 3).
`
`Detecting radiographic responses in heavily pre-treated patients with advanced metastatic
`disease is challenging, and even more so with immunotherapy where intratumoral
`inflammation and edema may minimize the relevance of standard RECIST criteria (26). As
`such, we obtained LM biopsies prior to and following CAR-T HAIs to assess degrees of
`intratumoral necrosis and fibrosis. After review by a blinded pathologist, 4 patients had an
`increase in intratumoral fibrosis and 3 patients were scored as having an increase in necrosis
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`within their LM (Figure 3B). An increase in LM fibrosis is demonstrated for patient # 1 and
`a decrease in CEA+ tumor cells by immunohistochemistry for patient # 8 (Figure 3C).
`
`Serum IFNγ concentrations and CEA responses correlate with IL2 administration
`We measured serum IFNγ levels by ELISA at multiple time points. Spikes in IFNγ were
`noted to occur 24–48 hours after doses in all patients, without or with systemic IL2
`(Supplemental Figure 4). Serum CEA changes were compared to peak change in IFNγ for
`each patient (Figure 3D, top). The inverse correlation between peak IFNγ levels and CEA
`change was significant (R=-0.94, p=0.02). All patient HAI CAR-T doses contained a
`quantity of IL2 (600,000 U). The three patients (#6, #7, and # 8) with continuous systemic
`IL2 exposure and largest CAR-T doses had the best CEA responses and the highest mean
`IFNγ levels (P=0.03, Figure 3D, bottom).
`
`DISCUSSION
`
`Our interest in immunotherapy for LM is based upon studies that have demonstrated LM
`patients with robust T cell responses have significantly improved outcomes. However, most
`LM patients fail to mount effective intrahepatic anti-tumor immunity (1). CAR-T
`technology has advanced considerably in recent years and holds tremendous promise (10,
`11) as an immunotherapeutic tool. We chose HAI of CAR-T to minimize immune mediated
`damage to CEA-expressing extrahepatic tissues and based upon the favorable therapeutic
`index of chemotherapy HAIs (20, 31). We established the safety of anti-CEA CAR-T HAIs
`with and without systemic IL2 support, reaching the maximum planned dose of 1010 cells.
`Systemic IL2 support was associated with increased serum IFNγ levels and improved CEA
`responses, at the expense of more severe but manageable adverse events. Although there
`were no radiographic partial or complete responses, 1 of 6 patients had stable disease and is
`alive at 23 months follow-up. Importantly, histologic evidence of increased LM necrosis and
`fibrosis were seen in the majority of subjects following CAR-T HAI.
`
`The safety of CAR-T HAIs is in line with reports from other groups (21, 23, 25, 32) that
`infused non-CAR cellular products into the hepatic circulation. The limited systemic
`exposure of CAR-T in our study subjects likely accounted for the favorable adverse event
`profile. HAI led to preferential accumulation of CAR-T within LM in 5 of 6 HITM patients,
`compared to normal liver and peripheral blood. CAR-Ts were not detected in the peripheral
`blood in 4 of 6 patients and only transiently in patients 7 and 8. Moderate elevations of liver
`function test values were likely related to the CAR-T HAI but did not result in clinically
`significant consequences. Systemic infusion of T cells expressing anti-CEA TCR was
`reported to result in dose-limiting toxicity (19). Similar toxicities have been seen with our
`CAR-T when systemically infused, particularly with IL2 support (RPJ, unpublished data).
`Our continuous ambulatory infusion dose of IL2, 75,000 U/kg/day, is several-fold lower
`than what is given in other protocols (33). Despite the low daily dose of the IL2 in this
`study, 2 patients experienced grade 3 events requiring IL2 dose reductions. We attributed
`these adverse events, including severe pyrexia and colitis, to the IL2 based upon the fact that
`the symptoms resolved promptly upon IL2 dose reduction. We cannot completely exclude
`the possibility that the IL2 activated a small number of systemically circulating anti-CEA
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`CAR-T that mediated fever and colitis. Overall, our IL2 infusion strategy was well tolerated
`and the adverse events easily managed by dose reductions.
`
`MRI and PET scans did not demonstrate a response in any patient, while one patient had
`stable disease and is alive more than 23 months following his final CAR-T HAI. Our
`patients were heavily pre-treated with profound disease burdens, with 4 of 6 patients
`presenting with more than 10 LM. Due to rapid disease progression following cessation of
`CAR-T infusions and IL2, we were unable to follow 5 of the 6 patients beyond 2 months,
`when responses to immunotherapy may manifest radiographically (26). We are encouraged
`by the CEA responses in the cohort that received IL2 and the evidence of necrosis and
`fibrosis following CAR-T HAI in several patients. Based on the timing of the biopsies, we
`cannot determine if IL2 alone or IL2 in combination with a higher CAR-T dose in cohort 2
`contributed to histologic findings (34). We also cannot reach definitive conclusions about
`the efficacy of our approach, but speculate that responses would be more favorable in
`patients with lower disease burdens. Interestingly, CEA declines may be inherently
`beneficial given the recently reported pro-angiogenic effects of CEA (35).
`
`To assess trafficking, we performed image-guided core biopsies of pre- and post-infusion
`LM and surrounding liver. We analyzed biopsy specimens for CAR+ cells, and studied the
`cell populations by flow cytometry. CAR+ T cells were present in detectable numbers in
`both tumor and normal liver after HAI, with numbers passing through liver being
`undetectable or only minimally detectable in peripheral blood. Similarly, in a parallel study
`with systemic administration of the same anti-CEA CAR-T, we demonstrated the presence
`of CAR+ cells by immunohistochemistry in normal liver and in tumor after infusion
`(Junghans et al, data not shown), thus confirming trafficking by this independent method.
`
`As to intrahepatic T cell distribution after HAI, Takayama and colleagues found a
`preferential localization in tumor versus normal liver after infusion of radiolabeled tumor
`infiltrating lymphocytes (TILs) (36). Our own flow cytometric analyses of core specimens in
`this study are also consistent with a conclusion of preferential tumor distribution of CAR T
`cells in 4/6 subjects after HAI. However, further directed assessments will be required to
`independently confirm this association on a statistical level.
`
`Performing detailed assessments of CAR-T phenotype and function can be challenging
`when working with a small sub-population of mononuclear cells isolated from core need
`biopsy specimens. Given the technical limitations related to detecting CAR-T in liver
`biopsies following infusion, alternative strategies including molecular imaging with MRI or
`PET scans (37), or radiolabeling as done by Takayama and colleagues (36) above, should
`receive consideration for future trials.
`
`Effective delivery of anti-CEA CAR-T to CEA+ tumor deposits also correlated with
`histologic evidence of tumor killing and serum cytokine surges (38). CEA responses were
`noted in 3 patients, all of whom received systemic IL2. IL2 alone is not expected to affect
`CEA levels, which presumptively implicates this fraction of CAR-T cells that traffic to
`tumor as mediating this effect. Prior work in this lab has shown tumor responses in animals
`
`Clin Cancer Res. Author manuscript; available in PMC 2016 July 15.
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`(34) and in humans (Junghans et al, unpublished results) with CAR-T cells that are
`dependent upon IL2 supplementation.
`
`One potential limitation on the activity of CAR-T in vivo would be the development of anti-
`CAR antibodies that could lead to rapid elimination of CAR+ cells. In the present instance,
`no patient developed an anti-CAR response. In many cases, the CAR includes foreign
`protein with a murine antibody domain that can elicit an immune response. In the current
`anti-CEA CAR, however, a CDR-grafted humanized version of the murine MN14 antibody
`(39) was selected for CAR engineering; such humanized antibodies are known to have much
`reduced immunization potential with only 4% incidence of anti-immunoglobulin responses
`in human clinical trials (40). Thus, the absence of anti-CAR antibody reaction in our patients
`is reassuring but not surprising.
`
`We speculate that improved CAR-T delivery by HAI may decrease the need for
`lymphodepl