A phase 2 study of a brachyury-targeting vaccine in combination with radiation therapy for the treatment of advanced chordoma.

BACKGROUND: This was a single-arm, phase 2 clinical trial of Bavarian Nordic (BN)-Brachyury vaccine plus radiotherapy (RT) designed to determine the objective response rate (ORR), progression-free survival (PFS), and safety of the combination in chordoma. METHODS: A total of 29 adult patients with advanced chordoma were treated with two subcutaneous priming vaccine doses of modified vaccinia Ankara-Bavarian Nordic (MVA-BN)-Brachyury and one vaccine dose of fowlpox virus (FPV)-Brachyury before RT. After RT, booster vaccinations were given with FPV-Brachyury every 4 weeks for 4 doses, then every 12 weeks (week 110). A minimum RT dose of >8 Gy in one fraction for each target was required. Response was evaluated by modified Response Evaluation Criteria in Solid Tumors 1.1 (mRECIST), where only radiated lesions were considered targets, and by standard RECIST 1.1 in a subset of patients. RESULTS: Two of 26 evaluable patients experienced durable partial response (PR) (ORR of 7.7%; 90% confidence interval [CI], 2.6-20.8]) by mRECIST 1.1. A total of 21 patients (80.8%; 90% CI, 65.4-90.3) had stable disease, and three patients (11.5%; 90% CI, 4.7-25.6) had progressive disease as best response per mRECIST 1.1. Median PFS was not reached during the study. CONCLUSIONS: This trial confirms the safety of BN-Brachyury and RT. Although the study did not meet the predefined study goal of four responses in 29 patients, we did observe two PRs and a PFS of greater than 2 years. For a vaccine-based study in chordoma, an ultra-rare disease where response rates are low, a randomized study or novel trial designs may be required to confirm activity.

Avelumab in Patients With Metastatic Colorectal Cancer.

BACKGROUND: Metastatic colorectal cancer (mCRC) is incurable, and median overall survival is less than 2½ years. Although monoclonal antibodies that block PD-1/PD-L1 interactions are active in microsatellite unstable/mismatch repair deficient tumors, a growing dataset shows that most patients with microsatellite stable/mismatch repair proficient tumors will not benefit from the blockade of PD-1/PD-L1 interactions. Here we present results from patients with mCRC (n = 22) treated with the anti-PD-L1 monoclonal antibody avelumab. METHODS: Patients received treatment on a phase I, open-label, dose-escalation trial via a consecutive parallel-group expansion in colorectal cancer. Patients aged 18 years and older with mCRC measurable by RECIST v1.1 who had received at least 1 line of systemic therapy for metastatic disease enrolled. Patients with prior immune checkpoint inhibitor treatment were excluded. Patients received avelumab 10 mg/kg intravenously every 2 weeks. The primary endpoint was the objective response rate. RESULTS: Twenty-two participants received treatment from July 2013 to August 2014. There were no objective responses and median progression-free survival was 2.1 months (95% CI: 1.4-5.5 months). There were 5 grade 3 treatment-related adverse events: GGT elevation (n = 2), PRESS (n = 1), lymphopenia (n = 1), and asymptomatic amylase/lipase elevation (n = 1). CONCLUSION: As demonstrated with other anti-PD-1/PD-L1 monoclonal antibodies, avelumab is not active in unselected patients with mCRC (ClinicalTrials.gov Identifier: NCT01772004).

The NIH pediatric/young adult chordoma clinic and natural history study: Making advances in a very rare tumor.

BACKGROUND: Chordomas are rare tumors arising from the skull base and spine, with approximately 20 pediatric chordoma cases in the Unitedn States per year. The natural history and optimal treatment of pediatric chordomas, especially poorly differentiated and dedifferentiated subtypes, is incompletely understood. Herein, we present findings from our first National Cancer Institute (NCI) chordoma clinic and a retrospective analysis of published cases of pediatric poorly differentiated chordomas (PDC) and dedifferentiated chordomas (DC). METHODS: Patients less than 40 years old with chordoma were enrolled on the NCI Natural History and Biospecimens Acquisitions Study for Children and Adults with Rare Solid Tumors protocol (NCT03739827). Chordoma experts reviewed patient records, evaluated patients, and provided treatment recommendations. Patient-reported outcomes, biospecimens, and volumetric tumor analyses were collected. A literature review for pediatric PDC and DC was conducted. RESULTS: Twelve patients (median age: 14 years) attended the clinic, including four patients with active disease and three patients with PDC responsive to systemic therapy. Consensus treatment, management, and recommendations were provided to patients. Literature review returned 45 pediatric cases of PDC or DC with variable treatments and outcomes. CONCLUSIONS: A multidisciplinary expert clinic was feasible and successful in improving understanding of pediatric chordoma. While multimodal approaches have all been employed, treatment for PDC has been inconsistent and a recommended standardized treatment approach has not been defined. Centralized efforts, inclusive of specialized chordoma-focused clinics, natural history studies, and prospective analyses will help in the standardization of care for this challenging disease.

Phase 3 Efficacy Trial of Modified Vaccinia Ankara as a Vaccine against Smallpox.

BACKGROUND: Many countries have stockpiled vaccines because of concerns about the reemergence of smallpox. Traditional smallpox vaccines are based on replicating vaccinia viruses; these vaccines have considerable side effects. METHODS: To evaluate the efficacy of modified vaccinia Ankara (MVA) as a potential smallpox vaccine, we randomly assigned 440 participants to receive two doses of MVA followed by one dose of the established replicating-vaccinia vaccine ACAM2000 (the MVA group) or to receive one dose of ACAM2000 (the ACAM2000-only group). The two primary end points were noninferiority of the MVA vaccine to ACAM2000 with respect to the peak serum neutralizing antibody titers and attenuation of the ACAM2000-associated major cutaneous reaction by previous MVA vaccination, measured according to the maximum lesion area and the derived area attenuation ratio. RESULTS: A total of 220 and 213 participants were randomly assigned and vaccinated in the MVA group and ACAM2000-only group, respectively, and 208 participants received two MVA vaccinations. At peak visits, MVA vaccination induced a geometric mean titer of neutralizing antibodies of 153.5 at week 6, as compared with 79.3 at week 4 with ACAM2000 (a ratio of 1.94 [95% confidence interval {CI}, 1.56 to 2.40]). At day 14, the geometric mean titer of neutralizing antibodies induced by a single MVA vaccination (16.2) was equal to that induced by ACAM2000 (16.2), and the percentages of participants with seroconversion were similar (90.8% and 91.8%, respectively). The median lesion areas of the major cutaneous reaction were 0 mm2 in the MVA group and 76.0 mm2 in the ACAM2000-only group, resulting in an area attenuation ratio of 97.9% (95% CI, 96.6 to 98.3). There were fewer adverse events or adverse events of grade 3 or higher after both MVA vaccination periods in the MVA group than in the ACAM2000-only group (17 vs. 64 participants with adverse events of grade 3 or higher, P<0.001). CONCLUSIONS: No safety concerns associated with the MVA vaccine were identified. Immune responses and attenuation of the major cutaneous reaction suggest that this MVA vaccine protected against variola infection. (Funded by the Office of the Assistant Secretary for Preparedness and Response Biomedical Advanced Research and Development Authority of the Department of Health and Human Services and Bavarian Nordic; ClinicalTrials.gov number, NCT01913353.).

Randomized, Double-Blind, Placebo-Controlled Phase II Study of Yeast-Brachyury Vaccine (GI-6301) in Combination with Standard-of-Care Radiotherapy in Locally Advanced, Unresectable Chordoma.

BACKGROUND: Brachyury is a transcription factor overexpressed in chordoma and is associated with chemotherapy resistance and epithelial-to-mesenchymal transition. GI-6301 is a recombinant, heat-killed Saccharomyces cerevisiae yeast-based vaccine targeting brachyury. A previous phase I trial of GI-6301 demonstrated a signal of clinical activity in chordomas. This trial evaluated synergistic effects of GI-6301 vaccine plus radiation. MATERIALS AND METHODS: Adults with locally advanced, unresectable chordoma were treated on a randomized, placebo-controlled trial. Patients received three doses of GI-6301 (80 × 107 yeast cells) or placebo followed by radiation, followed by continued vaccine or placebo until progression. Primary endpoint was overall response rate, defined as a complete response (CR) or partial response (PR) in the irradiated tumor site at 24 months. Immune assays were conducted to evaluate immunogenicity. RESULTS: Between May 2015 and September 2019, 24 patients enrolled on the first randomized phase II study in chordoma. There was one PR in each arm; no CRs were observed. Median progressive-free survival for vaccine and placebo arms was 20.6 months (95% confidence interval [CI], 5.7-37.5 months) and 25.9 months (95% CI, 9.2-30.8 months), respectively. Hazard ratio was 1.02 (95% CI, 0.38-2.71). Vaccine was well tolerated with no vaccine-related serious adverse events. Preexisting brachyury-specific T cells were detected in most patients in both arms. Most patients developed T-cell responses during therapy, with no difference between arms in frequency or magnitude of response. CONCLUSION: No difference in overall response rate was observed, leading to early discontinuation of this trial due to low conditional power to detect statistical difference at the planned end of accrual. IMPLICATIONS FOR PRACTICE: Chordoma is a rare neoplasm lacking effective systemic therapies for advanced, unresectable disease. Lack of clinically actionable somatic mutations in chordoma makes development of targeted therapy quite challenging. While the combination of yeast-brachyury vaccine (GI-6301) and standard radiation therapy did not demonstrate synergistic antitumor effects, brachyury still remains a good target for developmental therapeutics in chordoma. Patients and their oncologists should consider early referral to centers with expertise in chordoma (or sarcoma) and encourage participation in clinical trials.

Phase I Trial of a Modified Vaccinia Ankara Priming Vaccine Followed by a Fowlpox Virus Boosting Vaccine Modified to Express Brachyury and Costimulatory Molecules in Advanced Solid Tumors.

LESSONS LEARNED: Modified vaccinia Ankara-Bavarian Nordic (MVA-BN)-Brachyury followed by fowlpox virus-BN-Brachyury was well tolerated upon administration to patients with advanced cancer. Sixty-three percent of patients developed CD4+ and/or CD8+ T-cell responses to brachyury after vaccination. BN-Brachyury vaccine also induced T-cell responses against CEA and MUC1, which are cascade antigens, that is, antigens not encoded in the vaccines. BACKGROUND: Brachyury, a transcription factor, plays an integral role in the epithelial-mesenchymal transition, metastasis, and tumor resistance to chemotherapy. It is expressed in many tumor types, and rarely in normal tissues, making it an ideal immunologic target. Bavarian Nordic (BN)-Brachyury consists of vaccination with modified vaccinia Ankara (MVA) priming followed by fowlpox virus (FPV) boosting, each encoding transgenes for brachyury and costimulatory molecules. METHODS: Patients with metastatic solid tumors were treated with two monthly doses of MVA-brachyury s.c., 8 × 108 infectious units (IU), followed by FPV-brachyury s.c., 1 × 109 IU, for six monthly doses and then every 3 months for up to 2 years. The primary objective was to determine safety and tolerability. RESULTS: Eleven patients were enrolled from March 2018 to July 2018 (one patient was nonevaluable). No dose-limiting toxicities were observed. The most common treatment-related adverse event was grade 1/2 injection-site reaction observed in all patients. Best overall response was stable disease in six patients, and the 6-month progression-free survival rate was 50%. T cells against brachyury and cascade antigens CEA and MUC1 were detected in the majority of patients. CONCLUSION: BN-Brachyury vaccine is well tolerated and induces immune responses to brachyury and cascade antigens and demonstrates some evidence of clinical benefit.

Avelumab for metastatic or locally advanced previously treated solid tumours (JAVELIN Solid Tumor): a phase 1a, multicohort, dose-escalation trial.

BACKGROUND: Avelumab (MSB0010718C) is a human IgG1 monoclonal antibody that binds to PD-L1, inhibiting its binding to PD-1, which inactivates T cells. We aimed to establish the safety and pharmacokinetics of avelumab in patients with solid tumours while assessing biological correlatives for future development. METHODS: This open-label, single-centre, phase 1a, dose-escalation trial (part of the JAVELIN Solid Tumor trial) assessed four doses of avelumab (1 mg/kg, 3 mg/kg, 10 mg/kg, and 20 mg/kg), with dose-level cohort expansions to provide additional safety, pharmacokinetics, and target occupancy data. This study used a standard 3 + 3 cohort design and assigned patients sequentially at trial entry according to the 3 + 3 dose-escalation algorithm and depending on the number of dose-limiting toxicities during the first 3-week assessment period (the primary endpoint). Patient eligibility criteria included age 18 years or older, Eastern Cooperative Oncology Group performance status 0-1, metastatic or locally advanced previously treated solid tumours, and adequate end-organ function. Avelumab was given as a 1-h intravenous infusion every 2 weeks. Patients in the dose-limiting toxicity analysis set were assessed for the primary endpoint of dose-limiting toxicity, and all patients enrolled in the dose-escalation part were assessed for the secondary endpoints of safety (treatment-emergent and treatment-related adverse events according to National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0), pharmacokinetic and pharmacodynamic profiles (immunological effects), best overall response by Response Evaluation Criteria, and antidrug antibody formation. The population for the pharmacokinetic analysis included a subset of patients with rich pharmacokinetic samples from two selected disease-specific expansion cohorts at the same study site who had serum samples obtained at multiple early timepoints. This trial is registered with ClinicalTrials.gov, number NCT01772004. Patient recruitment to the dose-escalation part reported here is closed. FINDINGS: Between Jan 31, 2013, and Oct 8, 2014, 53 patients were enrolled (four patients at 1 mg/kg, 13 at 3 mg/kg, 15 at 10 mg/kg, and 21 at 20 mg/kg). 18 patients were analysed in the dose-limiting toxicity analysis set: three at dose level 1 (1 mg/kg), three at dose level 2 (3 mg/kg), six at dose level 3 (10 mg/kg), and six at dose level 4 (20 mg/kg). Only one dose-limiting toxicity occurred, at the 20 mg/kg dose, and thus the maximum tolerated dose was not reached. In all 53 enrolled patients (the safety analysis set), common treatment-related adverse events (occurring in >10% of patients) included fatigue (21 patients [40%]), influenza-like symptoms (11 [21%]), fever (8 [15%]), and chills (6 [11%]). Grade 3-4 treatment-related adverse events occurred in nine (17%) of 53 patients, with autoimmune disorder (n=3), increased blood creatine phosphokinase (n=2), and increased aspartate aminotransferase (n=2) each occurring in more than one patient (autoimmune disorder in two patients at 10 mg/kg and one patient at 20 mg/kg, increased blood creatine phosphokinase in two patients at 20 mg/kg, and increased aspartate aminotransferase in one patient at 1 mg/kg, and one patient at 10 mg/kg). Six (11%) of 53 patients had a serious treatment-related adverse event: autoimmune disorder (two [13%]), lower abdominal pain (one [7%]), fatigue (one [7%]), and influenza-like illness (one [7%]) in three patients treated at 10 mg/kg dose level, and autoimmune disorder (one [5%]), increased amylase (one [5%]), myositis (one [5%]), and dysphonia (one [5%]) in three patients who received the 20 mg/kg dose. We recorded some evidence of clinical activity in various solid tumours, with partial confirmed or unconfirmed responses in four (8%) of 53 patients; 30 (57%) additional patients had stable disease. Pharmacokinetic analysis (n=86) showed a dose-proportional exposure between doses of 3 mg/kg and 20 mg/kg and a half-life of 95-99 h (3·9-4·1 days) at the 10 mg/kg and 20 mg/kg doses. Target occupancy was greater than 90% at doses of 3 mg/kg and 10 mg/kg. Antidrug antibodies were detected in two (4%) of 53 patients. No substantial differences were found in absolute lymphocyte count or multiple immune cell subsets, including those expressing PD-L1, after treatment with avelumab. 31 (58%) of 53 patients in the overall safety population died; no deaths were related to treatment on study. INTERPRETATION: Avelumab has an acceptable toxicity profile up to 20 mg/kg and the maximum tolerated dose was not reached. Based on pharmacokinetics, target occupancy, and immunological analysis, we chose 10 mg/kg every 2 weeks as the dose for further development and phase 3 trials are ongoing. FUNDING: National Cancer Institute and Merck KGaA.

Predicting clinical outcomes in chordoma patients receiving immunotherapy: a comparison between volumetric segmentation and RECIST.

BACKGROUND: The Response Evaluation Criteria in Solid Tumors (RECIST) are the current standard for evaluating disease progression or therapy response in patients with solid tumors. RECIST 1.1 calls for axial, longest-diameter (or perpendicular short axis of lymph nodes) measurements of a maximum of five tumors, which limits clinicians' ability to adequately measure disease burden, especially in patients with irregularly shaped tumors. This is especially problematic in chordoma, a disease for which RECIST does not always adequately capture disease burden because chordoma tumors are typically irregularly shaped and slow-growing. Furthermore, primary chordoma tumors tend to be adjacent to vital structures in the skull or sacrum that, when compressed, lead to significant clinical consequences. METHODS: Volumetric segmentation is a newer technology that allows tumor burden to be measured in three dimensions on either MR or CT. Here, we compared the ability of RECIST measurements and tumor volumes to predict clinical outcomes in a cohort of 21 chordoma patients receiving immunotherapy. RESULTS: There was a significant difference in radiologic time to progression Kaplan-Meier curves between clinical outcome groups using volumetric segmentation (P = 0.012) but not RECIST (P = 0.38). In several cases, changes in volume were earlier and more sensitive reflections of clinical status. CONCLUSION: RECIST is a useful evaluation method when obvious changes are occurring in patients with chordoma. However, in many cases, RECIST does not detect small changes, and volumetric assessment was capable of detecting changes and predicting clinical outcome earlier than RECIST. Although this study was small and retrospective, we believe our results warrant further research in this area.

Resources Required for Semi-Automatic Volumetric Measurements in Metastatic Chordoma: Is Potentially Improved Tumor Burden Assessment Worth the Time Burden?

The Response Evaluation Criteria in Solid Tumors (RECIST) is the current standard for assessing therapy response in patients with malignant solid tumors; however, volumetric assessments are thought to be more representative of actual tumor size and hence superior in predicting patient outcomes. We segmented all primary and metastatic lesions in 21 chordoma patients for comparison to RECIST. Primary tumors were segmented on MR and validated by a neuroradiologist. Metastatic lesions were segmented on CT and validated by a general radiologist. We estimated times for a research assistant to segment all primary and metastatic chordoma lesions using semi-automated volumetric segmentation tools available within our PACS (v12.0, Carestream, Rochester, NY), as well as time required for radiologists to validate the segmentations. We also report success rates of semi-automatic segmentation in metastatic lesions on CT and time required to export data. Furthermore, we discuss the feasibility of volumetric segmentation workflow in research and clinical settings. The research assistant spent approximately 65 h segmenting 435 lesions in 21 patients. This resulted in 1349 total segmentations (average 2.89 min per lesion) and over 13,000 data points. Combined time for the neuroradiologist and general radiologist to validate segmentations was 45.7 min per patient. Exportation time for all patients totaled only 6 h, providing time-saving opportunities for data managers and oncologists. Perhaps cost-neutral resource reallocation can help acquire volumes paralleling our example workflow. Our results will provide researchers with benchmark resources required for volumetric assessments within PACS and help prepare institutions for future volumetric assessment criteria.

The impact of leukapheresis on immune-cell number and function in patients with advanced cancer.

BACKGROUND: Leukapheresis is often performed in cancer patients to harvest stem cells, manufacture therapeutic vaccines, or follow immunologic response to therapy. We have recently described the minimal impact of leukapheresis on normal donors. Here we provide additional immunologic data from patients with advanced cancer who underwent leukapheresis. METHODS: Using data from cancer patients on clinical trials who had leukapheresis (n = 64) or peripheral blood draws only (n = 90) as controls for immune analysis, we evaluated the impact of leukapheresis on number and function of lymphocytes. RESULTS: In the leukapheresis group, median age was 63.5 (range 38-82); 87.5 % were male. Comparing pre- and post-leukapheresis values within the groups, with each patient as its own control, there was no significant difference in enzyme-linked immunosorbent spot (ELISPOT), antivector humoral response, absolute lymphocyte count (ALC), or T cell number. Twelve patients completed three leukaphereses with subsequent ELISPOT analysis; seven had increased responses to flu (1.1- to 2.3-fold) with an even distribution around no change. Nineteen patients had matched ALC values after completing three leukaphereses with no significant change from baseline. CONCLUSIONS: These data provide evidence that leukapheresis has no detectable effects on a cancer patient's immune system in terms of number or function. These results contribute to a growing body of evidence refuting the hypothesis that a patient's immune competence is meaningfully affected by the procedure. Limitations include a restriction to 2-L leukapheresis procedure and small sample size.

Identification by digital immunohistochemistry of intratumoral changes of immune infiltrates after vaccine in the absence of modifications of PBMC immune cell subsets.

Preclinical studies have demonstrated that the combination of systemic subcutaneous (s.c.) vaccination with intratumoral (i.t.) vaccination was superior in the induction of antitumor activity vs. vaccination with either route alone. A subsequent phase I study employing i.t.-s.c. vaccination was carried out in men with locally recurrent or progressive prostate cancer. rF-PSA-TRICOM (PROSTVAC) vaccine was administered intraprostatically and rV-PSA-TRICOM followed by rF-PSA-TRICOM vaccine was administered systemically. In that study no dose limiting toxicities were observed, 19/21 patients had stable or improved prostate-specific antigen (PSA) values and tumor-infiltrating lymphocytes (TILs) increased in post- vs. pre-treatment tumor biopsies, analyzed employing conventional immunohistochemistry (IHC). In the studies reported here, 31 phenotypes of peripheral blood mononuclear cells (PBMCs) were analyzed prevaccination and postvaccination as well as the functions of PBMC regulatory T cells (Tregs) and natural killer cells. A trend was observed in decreases in serum PSA with the reduction of circulating Tregs postvaccination. Digital IHC was employed prevaccination and postvaccination to measure CD4 and CD8 TILs, as well as Treg TILs by conventional IHC. Few correlations were observed with CD4, CD8 or Treg in TILs vs. PBMCs. However, patients with lower levels of CD4 TILs prevaccination showed the greatest increases in CD4 TILs postvaccine, while Treg TILs decreased postvaccine. There was also a strong correlation between decreases in serum PSA and increases in CD8 TILs postvaccine. These studies provide additional rationale for the use of i.t.-s.c. vaccinations and demonstrate a noncoordinate expression of specific immune subsets in PBMCs vs. tumor.

Phase I trial of a recombinant yeast-CEA vaccine (GI-6207) in adults with metastatic CEA-expressing carcinoma.

Yeast-CEA (GI-6207) is a therapeutic cancer vaccine genetically modified to express recombinant carcinoembryonic antigen (CEA) protein, using heat-killed yeast (Saccharomyces cerevisiae) as a vector. In preclinical studies, yeast-CEA induced a strong immune response to CEA and antitumor responses. Patients received subcutaneous vaccines every 2 weeks for 3 months and then monthly. Patients were enrolled at 3 sequential dose levels: 4, 16, and 40 yeast units (10(7) yeast particles/unit). Eligible patients were required to have serum CEA > 5 ng/mL or > 20 % CEA(+) tumor block, ECOG PS 0-2, and no history of autoimmunity. Restaging scans were performed at 3 months and then bimonthly. Peripheral blood was collected for the analysis of immune response (e.g., by ELISPOT assay). Twenty-five patients with metastatic CEA-expressing carcinomas were enrolled. Median patient age was 52 (range 39-81). A total of 135 vaccines were administered. The vaccine was well tolerated, and the most common adverse event was grade 1/2 injection-site reaction. Five patients had stable disease beyond 3 months (range 3.5-18 months), and each had CEA stabilization while on-study. Some patients showed evidence post-vaccination of increases in antigen-specific CD8(+) T cells and CD4(+) T lymphocytes and decreases in regulatory T cells. Of note, a patient with medullary thyroid cancer had substantial T cell responses and a vigorous inflammatory reaction at sites of metastatic disease. Yeast-CEA vaccination had minimal toxicity and induced some antigen-specific T cell responses and CEA stabilization in a heterogeneous, heavily pre-treated patient population. Further studies are required to determine the clinical benefit of yeast-CEA vaccination.

Phase I study of intraprostatic vaccine administration in men with locally recurrent or progressive prostate cancer.

The primary end point of this study was to determine the safety and feasibility of intraprostatic administration of PSA-TRICOM vaccine [encoding transgenes for prostate-specific antigen (PSA) and 3 costimulatory molecules] in patients with locally recurrent or progressive prostate cancer. This trial was a standard 3 + 3 dose escalation with 6 patients each in cohorts 4 and 5 to gather more immunologic data. Nineteen of 21 patients enrolled had locally recurrent prostate cancer after definitive radiation therapy, and 2 had no local therapy. All cohorts received initial subcutaneous vaccination with recombinant vaccinia (rV)-PSA-TRICOM and intraprostatic booster vaccinations with recombinant fowlpox (rF)-PSA-TRICOM. Cohorts 3-5 also received intraprostatic rF-GM-CSF. Cohort 5 received additional subcutaneous boosters with rF-PSA-TRICOM and rF-GM-CSF. Patients had pre- and post-treatment prostate biopsies, and analyses of peripheral and intraprostatic immune cells were performed. There were no dose-limiting toxicities, and the maximum tolerated dose was not reached. The most common grade 2 adverse events were fever (38%) and subcutaneous injection site reactions (33%); the single grade 3 toxicity was transient fever. Overall, 19 of 21 patients on trial had stable (10) or improved (9) PSA values. There was a marked increase in CD4+ (p = 0.0002) and CD8+ (p = 0.0002) tumor infiltrates in post- versus pre-treatment tumor biopsies. Four of 9 patients evaluated had peripheral immune responses to PSA or NGEP. Intraprostatic administration of PSA-TRICOM is safe and feasible and can generate a significant immunologic response. Improved serum PSA kinetics and intense post-vaccination inflammatory infiltrates were seen in the majority of patients. Clinical trials examining clinical end points are warranted.

Dose fractionation of CAR-T cells. A systematic review of clinical outcomes.

CAR-T cells are widely recognized for their potential to successfully treat hematologic cancers and provide durable response. However, severe adverse events such as cytokine release syndrome (CRS) and neurotoxicity are concerning. Our goal is to assess CAR-T cell clinical trial publications to address the question of whether administration of CAR-T cells as dose fractions reduces toxicity without adversely affecting efficacy. Systematic literature review of studies published between January 2010 and May 2022 was performed on PubMed and Embase to search clinical studies that evaluated CAR-T cells for hematologic cancers. Studies published in English were considered. Studies in children (age < 18), solid tumors, bispecific CAR-T cells, and CAR-T cell cocktails were excluded. Data was extracted from the studies that met inclusion and exclusion criteria. Review identified a total of 18 studies that used dose fractionation. Six studies used 2-day dosing schemes and 12 studies used 3-day schemes to administer CAR-T cells. Three studies had both single dose and fractionated dose cohorts. Lower incidence of Grade ≥ 3 CRS and neurotoxicity was seen in fractionated dose cohorts in 2 studies, whereas 1 study reported no difference between single and fractionated dose cohorts. Dose fractionation was mainly recommended for high tumor burden patients. Efficacy of CAR-T cells in fractionated dose was comparable to single dose regimen within the same or historical trial of the same agent in all the studies. The findings suggest that administering dose fractions of CAR-T cells over 2-3 days instead of single dose infusion may mitigate the toxicity of CAR-T cell therapy including CRS and neurotoxicity, especially in patients with high tumor burden. However, controlled studies are likely needed to confirm the benefits of dose fractionation.

Phase 1 study of CART-ddBCMA for the treatment of subjects with relapsed and refractory multiple myeloma.

Relapsed and refractory multiple myeloma (RRMM) is a plasma cell neoplasm defined by progressively refractory disease necessitating chronic and increasingly intensive therapy. Despite recent advances, limited treatment options exist for RRMM. This single-arm, open label phase 1 study aimed to evaluate the safety of novel B-cell maturation antigen (BCMA)-targeting chimeric antigen receptor (CAR) T construct that leverages a completely synthetic antigen-binding domain (CART-ddBCMA), which was specifically engineered to reduce immunogenicity and improve CAR cell surface stability. Thirteen patients ≥18 years with RRMM who received at least 3 prior regimens of systemic therapy were enrolled in the study. Patients received a single dose of 100 × 106 CART-ddBCMA (DL1) or 300 × 106 CART-ddBCMA (DL2) following standard lymphodepleting chemotherapy. The primary endpoints of the study were to evaluate the incidence of treatment emergent adverse events, including dose-limiting toxicities, and establish a recommended phase 2 dose. Results showed that CART-ddBCMA was well tolerated and demonstrated a favorable toxicity profile. Only 1 case of grade ≥3 cytokine release syndrome and 1 case of immune effector cell-associated neurotoxicity were reported; both were at DL2 and were manageable with standard treatment. No atypical neurological toxicities and Parkinson disease-like movement disorders were observed. The maximum tolerated dose was not reached. All infused patients responded to CART-ddBCMA, and 9/12 (75%) patients achieved complete response/stringent complete response. Responses deepened over time, and at the time of last data-cut (median follow-up 56 weeks), 8/9 (89%) evaluable patients achieved minimal residual disease negativity. In conclusion, the findings demonstrate the safety of CART-ddBCMA cells and document durable responses to CART-ddBCMA in patients with RRMM. This trial was registered at www.clinicaltrials.gov as #NCT04155749.

Dose-response correlation for CAR-T cells: a systematic review of clinical studies.

The potential of chimeric antigen receptor (CAR) T cells to successfully treat hematological cancers is widely recognized. Multiple CAR-T cell therapies are currently under clinical development, with most in early stage, during which dose selection is a key goal. The objective of this review is to address the question of dose-dependent effects on response and/or toxicity from available CAR-T cell clinical trial data. For that purpose, systematic literature review of studies published between January 2010 and May 2022 was performed on PubMed and Embase to search clinical studies that evaluated CAR-T cells for hematological cancers. Studies published in English were considered. Studies in children (age <18 years), solid tumors, bispecific CAR-T cells and CAR-T cell cocktails were excluded. As a result, a total of 74 studies met the inclusion criteria. Thirty-nine studies tested multiple dose levels of CAR-T cells with at least >1 patient at each dose level. Thirteen studies observed dose-related increase in disease response and 23 studies observed dose-related increase in toxicity across a median of three dose levels. Optimal clinical efficacy was seen at doses 50-100 million cells for anti-CD19 CAR-T cells and >100 million cells for anti-BCMA CAR-T cells in majority of studies. The findings suggest, for a given construct, there exists a dose at which a threshold of optimal efficacy occurs. Dose escalation may reveal increasing objective response rates (ORRs) until that threshold is reached. However, when ORR starts to plateau despite increasing dose, further dose escalation is unlikely to result in improved ORR but is likely to result in higher incidence and/or severity of mechanistically related adverse events.

Phase 1 open-label trial of intravenous administration of MVA-BN-brachyury-TRICOM vaccine in patients with advanced cancer.

BACKGROUND: MVA-BN-brachyury-TRICOM is a recombinant vector-based therapeutic cancer vaccine designed to induce an immune response against brachyury. Brachyury, a transcription factor overexpressed in advanced cancers, has been associated with treatment resistance, epithelial-to-mesenchymal transition, and metastatic potential. MVA-BN-brachyury-TRICOM has demonstrated immunogenicity and safety in previous clinical trials of subcutaneously administered vaccine. Preclinical studies have suggested that intravenous administration of therapeutic vaccines can induce superior CD8+ T cell responses, higher levels of systemic cytokine release, and stronger natural killer cell activation and proliferation. This is the first-in-human study of the intravenous administration of MVA-BN-brachyury-TRICOM. METHODS: Between January 2020 and March 2021, 13 patients were treated on a phase 1, open-label, 3+3 design, dose-escalation study at the National Institutes of Health Clinical Center. The study population was adults with advanced solid tumors and was enriched for chordoma, a rare sarcoma of the notochord that overexpresses brachyury. Vaccine was administered intravenously at three DLs on days 1, 22, and 43. Blood samples were taken to assess drug pharmacokinetics and immune activation. Imaging was conducted at baseline, 1 month, and 3 months post-treatment. The primary endpoint was safety and tolerability as determined by the frequency of dose-limiting toxicities; a secondary endpoint was determination of the recommended phase 2 dose. RESULTS: No dose-limiting toxicities were observed and no serious adverse events were attributed to the vaccine. Vaccine-related toxicities were consistent with class profile (ie, influenza-like symptoms). Cytokine release syndrome up to grade 2 was observed with no adverse outcomes. Dose-effect trend was observed for fever, chills/rigor, and hypotension. Efficacy analysis of objective response rate per RECIST 1.1 at the end of study showed one patient with a partial response, four with stable disease, and eight with progressive disease. Three patients with stable disease experienced clinical benefit in the form of improvement in pain. Immune correlatives showed T cell activation against brachyury and other tumor-associated cascade antigens. CONCLUSIONS: Intravenous administration of MVA-BN-brachyury-TRICOM vaccine was safe and tolerable. Maximum tolerated dose was not reached. The maximum administered dose was 109 infectious units every 3 weeks for three doses. This dose was selected as the recommended phase 2 dose. TRIAL REGISTRATION NUMBER: NCT04134312.

Neoadjuvant PROSTVAC prior to radical prostatectomy enhances T-cell infiltration into the tumor immune microenvironment in men with prostate cancer.

BACKGROUND: Clinical trials have shown the ability of therapeutic vaccines to generate immune responses to tumor-associated antigens (TAAs). What is relatively less known is if this translates into immune-cell (IC) infiltration into the tumor microenvironment. This study examined whether neoadjuvant prostate-specific antigen (PSA)-targeted vaccination with PROSTVAC could induce T-cell immunity, particularly at the tumor site. METHODS: An open-label, phase II study of neoadjuvant PROSTVAC vaccine enrolled 27 patients with localized prostate cancer awaiting radical prostatectomy (RP). We evaluated increases in CD4 and CD8 T-cell infiltrates (RP tissue vs baseline biopsies) using a six-color multiplex immunofluorescence Opal method. Antigen-specific responses were assessed by intracellular cytokine staining after in vitro stimulation of peripheral blood mononuclear cells with overlapping 15-mer peptide pools encoding the TAAs PSA, brachyury and MUC-1. RESULTS: Of 27 vaccinated patients, 26 had matched prevaccination (biopsy) and postvaccination (RP) prostate samples available for non-compartmentalized analysis (NCA) and compartmentalized analysis (CA). Tumor CD4 T-cell infiltrates were significantly increased in postvaccination RP specimens compared with baseline biopsies by NCA (median 176/mm² vs 152/mm²; IQR 136-317/mm² vs 69-284/mm²; p=0.0249; median ratio 1.20; IQR 0.64-2.25). By CA, an increase in both CD4 T-cell infiltrates at the tumor infiltrative margin (median 198/mm² vs 151/mm²; IQR 123-500/mm² vs 85-256/mm²; p=0.042; median ratio 1.44; IQR 0.59-4.17) and in CD8 T-cell infiltrates at the tumor core (median 140/mm² vs 105/mm²; IQR 91-175/mm² vs 83-163/mm²; p=0.036; median ratio 1.25; IQR 0.88-2.09) were noted in postvaccination RP specimens compared with baseline biopsies. A total of 13/25 patients (52%) developed peripheral T-cell responses to any of the three tested TAAs (non-neoantigens); five of these had responses to more than one antigen of the three evaluated. CONCLUSION: Neoadjuvant PROSTVAC can induce both tumor immune response and peripheral immune response. TRIAL REGISTRATION NUMBER: NCT02153918.

First-in-Human Phase I Trial of a Tumor-Targeted Cytokine (NHS-IL12) in Subjects with Metastatic Solid Tumors.

PURPOSE: The NHS-IL12 immunocytokine is composed of two IL12 heterodimers fused to the NHS76 antibody. Preclinical studies have shown that this antibody targets IL12 to regions of tumor necrosis by binding histones on free DNA fragments in these areas, resulting in enhanced antitumor activity. The objectives of this phase I study were to determine the maximum tolerated dose (MTD) and pharmacokinetics of NHS-IL12 in subjects with advanced solid tumors. PATIENTS AND METHODS: Subjects (n = 59) were treated subcutaneously with NHS-IL12 in a single ascending-dose cohort followed by a multiple ascending-dose cohort (n = 37 with every 4-week dosing). RESULTS: The most frequently observed treatment-related adverse events (TRAE) included decreased circulating lymphocytes, increased liver transaminases, and flu-like symptoms. Of the grade ≥3 TRAEs, all were transient and only one was symptomatic (hyperhidrosis). The MTD is 16.8 µg/kg. A time-dependent rise in IFNγ and an associated rise in IL10 were observed following NHS-IL12. Of peripheral immune cell subsets evaluated, most noticeable were increases in frequencies of activated and mature natural killer (NK) cells and NKT cells. Based on T-cell receptor sequencing analysis, increases in T-cell receptor diversity and tumor-infiltrating lymphocyte density were observed after treatment where both biopsies and peripheral blood mononuclear cells were available. Although no objective tumor responses were observed, 5 subjects had durable stable disease (range, 6-30+ months). CONCLUSIONS: NHS-IL12 was well tolerated up to a dose of 16.8 µg/kg, which is the recommended phase II dose. Early clinical immune-related activity warrants further studies, including combination with immune checkpoint inhibitors.See related commentary by Lyerly et al., p. 9.

Phase I trial of HuMax-IL8 (BMS-986253), an anti-IL-8 monoclonal antibody, in patients with metastatic or unresectable solid tumors.

BACKGROUND: HuMax-IL8 (now known as BMS-986253) is a novel, fully human monoclonal antibody that inhibits interleukin-8 (IL-8), a chemokine that promotes tumor progression, immune escape, epithelial-mesenchymal transition, and recruitment of myeloid-derived suppressor cells. Studies have demonstrated that high serum IL-8 levels correlate with poor prognosis in many malignant tumors. Preclinical studies have shown that IL-8 blockade may reduce mesenchymal features in tumor cells, making them less resistant to treatment. METHODS: Fifteen patients with metastatic or unresectable locally advanced solid tumors were enrolled in this 3 + 3 dose-escalation trial at four dose levels (4, 8, 16, or 32 mg/kg). HuMax-IL8 was given IV every 2 weeks, and patients were followed for safety and immune monitoring at defined intervals up to 52 weeks. RESULTS: All enrolled patients (five chordoma, four colorectal, two prostate, and one each of ovarian, papillary thyroid, chondrosarcoma, and esophageal) received at least one dose of HuMax-IL8. Eight patients had received three or more prior lines of therapy and five patients had received prior immunotherapy. Treatment-related adverse events occurred in five patients (33%), mostly grade 1. Two patients receiving the 32 mg/kg dose had grade 2 fatigue, hypophosphatemia, and hypersomnia. No dose-limiting toxicities were observed, and maximum tolerated dose was not reached. Although no objective tumor responses were observed, 11 patients (73%) had stable disease with median treatment duration of 24 weeks (range, 4-54 weeks). Serum IL-8 was significantly reduced on day 3 of HuMax-IL8 treatment compared to baseline (p = 0.0004), with reductions in IL-8 seen at all dose levels. CONCLUSIONS: HuMax-IL8 is safe and well-tolerated. Ongoing studies are evaluating the combination of IL-8 blockade and other immunotherapies. TRIAL REGISTRATION: NCTN, NCT02536469. Registered 23 August 2015, https://clinicaltrials.gov/ct2/show/NCT02536469?term=NCT02536469&rank=1 .