Block, Matthew S.

AbstractBackgroundMerkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy that usually occurs in the head/neck or extremities. However, there are reports of MCC developing in the lymph nodes or parotid gland without evidence of a primary cutaneous lesion.MethodsWe reviewed 415 patients with biopsy‐proven MCC. Patients with MCC of unknown primary (n = 37, 9%, MCCUP) made up the study cohort. The primary endpoints of the study were rate of recurrence, disease‐free survival, and overall survival.ResultsPatients with MCCUP presented with tumors in lymph nodes (n = 34) or parotid gland (n = 3). Nodal disease was most commonly detected in the inguinal/external iliac (n = 15) or axillary (n = 14) regions. The mean age at diagnosis was 70 years and 24% were female. Patients presented with distant metastases in 24.3% of cases. Patients with stage IIIA disease treated with regional lymph node dissection (RLND) had a lower risk of disease recurrence (hazard ratio 0.26, p = 0.046). Recurrence‐free survival was 59.3% at 5 years. Disease‐specific survival was 63.3% at 5 years.ConclusionPatients with MCCUP have a high risk of recurrence and mortality. The optimal treatment for MCCUP has yet to be elucidated, although therapeutic RLND appears beneficial for these patients.

Abstract Background: Cancer mutations acquired during carcinogenesis are not subject to central tolerance and thus, are cornerstone in cancer immunosurveillance. The use of mutation-derived neoepitopes to design cancer vaccines is an unprecedented opportunity to target efficient antigens, but the stochastic occurrence of mutations implies that a tailored vaccine needs to be designed and manufactured for each patient. We used next generation sequencing, machine learning based genomic data analysis and advances in genome editing to systematically identify private neoepitopes in high-risk HPV negative HNSCC and relapsing OvC patients. Methods: Mutations were identified by DNA and RNA sequencing and putative epitopes were selected for vaccine design on their likelihood to elicit a class I or II response based on HLA binding, allelic frequency, prediction of processing and expression at RNA level. The vaccine was a recombinant virus of the modified Vaccinia Ankara (MVA) strain encoding for up to 30 sequences of 29 amino acids centred on the predicted epitope and flanked with the normal germline sequence in case of missense mutations, and of the mutated protein sequence in case of frameshift mutations. The viral vaccine was amplified under GMP conditions and administered to patients after curative intent treatment in two phase I trials. Treatment was started for OvC patients at relapse defined as elevation of CA-125 or onset of suspicious radiological findings and, after first line therapy for HNSCC patients with locally advanced disease with either extracapsular extension or positive resection margins following upfront surgery. The vaccine was administered for 6 weeks and a booster dose every three weeks over a year, in absence of other cancer therapy. Results: Six patients (4 OvC and 2 HNSCC) were treated and experienced only mild related adverse events. After 6 doses of vaccine, we measured immunoreactive T cells in PBMCs against each of the targeted epitopes using an ex vivo IFNγ ELISPOT showed robust responses in all evaluable patients. Positive responses to vaccination were observed for a total of 46 epitopes over 115 tested with a median of 11 epitopes (6 to 18) per patient. Responses were directed against both class I and II epitopes and were either de novo responses (64%) or amplification of pre-existing responses (36%). In parallel, phenotyping of patient PBMCs showed, in all treated patients, a decline in naïve CD4 and CD8 cells and the onset of effector CD27- CD4 and CD27-/CD57+ CD8; similarly, CD56dim NK cells increased suggesting a stimulation of antitumor innate immunity. In one ovarian cancer patient, these immune changes correlated with a normalization of CA-125 that lasted 7 months. Conclusions: These data show that the personalized approach with TG4050 is feasible, safe and immunogenic. The two phase I trials are ongoing. Citation Format: Matthew S. Block, Jean-Pierre Delord, Christian H. Ottensmeier, Christophe Le Tourneau, Ana Lalanne, Olivier Lantz, Keith L. Knutson, Gisèle Lacoste, Annette Tavernaro, Maud Brandely, Nathalie Silvestre, Benoit Grellier, Yoshiko Yamashita, Onoue Kousuke, Naoko Yamagata, Eric Quemeneur, Kaidre Bendjama. Phase I trials of personalized cancer vaccine TG4050 in surgically treated high-risk head and neck squamous cell carcinoma (HNSCC) and relapsing ovarian cancer (OvC) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT182.

9573 Background: Mucosal melanoma is a rare, highly aggressive form of melanoma with extremely high recurrence rates, despite definitive surgical resection. Median RFS has been reported to be 5.4m, with RFS rates at 1 and 2 years of 10%, and 0%, respectively (Lian B, Si L, Cui C, et al. Phase II Randomized Trial Comparing High-Dose IFN-α2b with Temozolomide Plus Cisplatin as Systemic Adjuvant Therapy for Resected Mucosal Melanoma. Clinical Cancer Research 2013, 19(16):4488-4498). Currently there is no consensus on recommendations for adjuvant therapy. Data on the use of immune checkpoint inhibitors (ICI) adjuvantly is lacking. Methods: We performed a single arm, multicenter clinical trial using “flip dose” ipilimumab (1mg/kg q3w x4 cycles),and nivolumab (3 mg.kg q3w x4 cycles), then Nivolumab 480 mg q4w x 11 cycles to complete a year of adjuvant therapy. The primary endpoint was recurrence-free survival (RFS), and the study had 85% power to detect an improvement in RFS between 5.5 and 9.5 months using a one-sided log rank test. Participants must have had R0/R1 resection <90 days prior to registration, and no prior systemic therapy (adjuvant radiation allowed), ECOG 0/1, no uncontrolled significant autoimmune disease or other invasive cancer. Patients were recruited through the Midwest Melanoma Partnership/Hoosier Oncology Network. Results: From 9/17 to 8/21, 44 patients were approached at 6 centers. Of these 9 were ineligible, and 35 were enrolled. Of these, 29 (83%) had R0 resections, and 7 (20%) had adjuvant radiation prior to enrollment. As of Dec 2021, 31 patients have completed the treatment phase. Of the 35 patients treated on study, 20 patients have recurred (7 local, 5 distant, 3 regional, 5 sites unconfirmed), 6 stopped therapy due to adverse effects, and 8 have died. The mean age of patients was 65.8 years and 21 (60.0%) were female. The primary site of disease was vulvovaginal N=12 (32.4%) patients, sinonasal N= 11 (29.7%), anorectal N= 9 (24.3%) and other site N= 5 (13.5%). Adjuvant radiation had been given in 7 pts. Driver mutations were rare, with only 3 (8.6%) patients having a KIT mutation, and one patient (2.9%) each having a NRAS or BRAF mutation. RFS rates at 1 and 2 years were 50% (95% CI 31-66%) and 37% (95% CI 19-55%), with OS rates at 1 and 2 years of 87% (95% CI 68-95%) and 68% (95% CI 46-83%). Median RFS was 10.3 m (95% CI5.7-25.8). Most common grade 3 adverse events were diarrhea (14%), hypertension (14%), hyponatremia (11%), with no grade 4/5 toxicities. Conclusions: Flip dose ipilimumab and nivolumab after resection is associated with outcomes improved over previously reported outcomes in the absence of therapy. Long term follow up is ongoing as are subgroup analyses and correlative studies. Clinical trial information: NCT03241186.

2637 Background: Mutation-associated neoantigens (MANAs) constitute attractive antigens for the design of cancer vaccines. However, clinical implementation remains challenging because of the patient specific nature of MANAs, hereby requiring that a bespoke vaccine is designed for each subject. We developed a pipeline for the genomic characterization and the design of tailored vaccine using a modified vaccinia Ankara viral vector. Methods: Immunogenicity, safety and early clinical activity of personalized cancer vaccines are being assessed in two phase I trials, respectively in high grade serous OC and HPV-negative HNSCC. Patients (Pts) at high risk of relapse are enrolled in the study being in remission following surgical primary treatment. High risk is defined as stage IIIC or IVA for OC and stage III or IVA for HNSCC. A vaccine is manufactured for each patient. OC pts are treated at asymptomatic relapse based on radiological finding or elevation of CA-125 with the vaccine alone; HNSCC pts in complete remission after surgery and adjuvant therapy are randomized to receive the vaccine either at the end of locoregional treatment or in combination with standard of care at relapse. The vaccine was administered weekly for 6 weeks and a booster dose every three weeks over a year or until progression, whichever occurred first. Results: At the time of the data cut-off, a total of 8 pts were treated: 4 relapsing OC pts, 3 HNSCC pts in complete remission and 1 relapsing HNSCC pt. AE attributable to the vaccine were mainly grade 1 injection site reactions and fatigue. One OC pt displayed an objective response 6 weeks after initiation of vaccine and for 9 months with a normalization of CA-125 until death from an unrelated cause; 1 other OC pt remains on treatment with a stable radiological disease for 11 months. The 2 other OC progressed at the first evaluation on day 43. HNSCC pts treated in complete remission received respectively 20, 15 and 4 doses, and remain on treatment and disease free. One HNSCC patient received 9 doses of vaccine after relapse in conjunction with chemotherapy and anti-PD-1 therapy and remains on treatment with stable disease after 5 months. Immune monitoring demonstrates priming of a polyepitopic T cell response against class I and II antigens. Responses were observed regardless of HLA and without cross-reactivity to the germline protein. Adaptive response was associated with a shift of CD4 and CD8 T cells toward an effector phenotype and innate cellular immunity was activated with a strong maturation and activation of NK cells. Immune changes were stronger in pts with controlled disease versus progressors. Conclusions: Data demonstrate that TG4050 is safe, well tolerated and able to induce T cell responses whatever the HLA haplotype. Early signs of clinical activity were observed in OC pt. These data pave the way for further development and synergistic immunotherapeutic combinations. Clinical trial information: NCT04183166.

Background Combining immunotherapy and antiangiogenic agents is a promising treatment strategy in endometrial cancer. To date, no biomarkers for response have been identified and data on post-immunotherapy progression are lacking. We explored the combination of a checkpoint inhibitor (nivolumab) and an antiangiogenic agent (cabozantinib) in immunotherapy-naïve endometrial cancer and in patients whose disease progressed on previous immunotherapy with baseline biopsy for immune profiling. Patients and methods In this phase II trial (ClinicalTrials.gov NCT03367741, registered December 11, 2017), women with recurrent endometrial cancer were randomized 2:1 to nivolumab with cabozantinib (Arm A) or nivolumab alone (Arm B). The primary endpoint was Response Evaluation Criteria in Solid Tumors-defined progression-free survival (PFS). Patients with carcinosarcoma or prior immune checkpoint inhibitor received combination treatment (Arm C). Baseline biopsy and serial peripheral blood mononuclear cell (PBMC) samples were analyzed and associations between patient outcome and immune data from cytometry by time of flight (CyTOF) and PBMCs were explored. Results Median PFS was 5.3 (90% CI 3.5 to 9.2) months in Arm A (n=36) and 1.9 (90% CI 1.6 to 3.4) months in Arm B (n=18) (HR=0.59, 90% CI 0.35 to 0.98; log-rank p=0.09, meeting the prespecified statistical significance criteria). The most common treatment-related adverse events in Arm A were diarrhea (50%) and elevated liver enzymes (aspartate aminotransferase 47%, alanine aminotransferase 42%). In-depth baseline CyTOF analysis across treatment arms (n=40) identified 35 immune-cell subsets. Among immunotherapy-pretreated patients in Arm C, non-progressors had significantly higher proportions of activated tissue-resident (CD103+CD69+) ɣδ T cells than progressors (adjusted p=0.009). Conclusions Adding cabozantinib to nivolumab significantly improved outcomes in heavily pretreated endometrial cancer. A subgroup of immunotherapy-pretreated patients identified by baseline immune profile and potentially benefiting from combination with antiangiogenics requires further investigation.

Abstract The most common adverse event (AE) of dabrafenib and trametinib (DT) is pyrexia, which has been reported to occur in up to 71% of patients. Pyrexia resulted in therapy discontinuation in up to 26% of patients who otherwise were benefiting from the treatment. Little is known about the pathogenesis and optimal management of this common AE. We hypothesized that the etiology of pyrexia in patients treated with DT could be extrapolated from DT-related cutaneous adverse effects in which a paradoxical MAPK pathway activation has been identified. We hypothesized that the mechanism of MAPK pathway activation with DT therapy is similar to that reported in patients with familial Mediterranean fever (FMF), a rare, inherited condition characterized by episodes of fever and rash that responds exceedingly well to colchicine-based therapy. Based on this association, our group explored the use of oral colchicine for the treatment of DT-associated pyrexia in five patients with metastatic melanoma. Citation Format: Jesus Vera, Jonas Paludo, Lisa Kottschade, Matthew Block, Yiyi Yan, Charles Loprinzi, Svetomir Markovic. Dabrafenib-trametinib-induced pyrexia successfully treated with colchicine [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B15.

Introduction Immune-mediated hematologic disorders are relatively rare but potentially life-threatening immune-related adverse events (irAE) with immune checkpoint inhibitor (ICI) therapy (Shiuan, Beckermann et al 2017). The management strategy often relies on systemic corticosteroids and other immunosuppressant agents in steroid-refractory cases (Brahmer, Lacchetti et al 2018). We hereby describe our institution's experience in diagnosing and managing immune-related hematologic adverse events (ir-h-AE). Methods We retrospectively searched the electronic health record for all ir-h-AE diagnosed by treating providers and confirmed by study authors between 2015 and 2020. The search included patients on ICI and the following conditions: immune-related neutropenia (IRN), autoimmune hemolytic anemia (AIHA), cold agglutinin disease (CAD), immune thrombocytopenia (ITP), immune-related pancytopenia, aplastic anemia (AA), and pure red cell aplasia (PRCA). For AIHA, PRCA, and CAD, partial response (PR) was defined as hemoglobin greater than 10 g/dL but &lt; 12 g/dL and 2 g/dL above the nadir without blood product transfusion. Complete response (CR) was defined as hemoglobin of ≥ 12 g/dL and 2 g/dL above the nadir without blood product transfusion (Peñalver, Alvarez-Larrán et al. 2010). For ITP, CR was defined as platelet count ≥ 100 × 109/L and absence of bleeding. PR was defined as platelet count ≥ 30 × 109/L and ≥ two-fold increase from the baseline count and absence of bleeding (Gómez-Almaguer, Tarín-Arzaga et al. 2013). For IRN, CR was defined as absolute neutrophil count (ANC) ≥ 1500/ mm3 on 2 consecutive measurements separated by 7 days; PR was defined as ANC ≥ 500/ mm3 sustained over 7 days. JMP® 14.1 was used for data analysis. Results Seventeen patients were identified, 9 (52.9%) of whom were female (table 1). Median age was 68 years (range 26-78). The most common pre-existing malignancies were melanoma (6 patients, 35.3%), non-small cell lung cancer (4 patients, 23.5%), and gastrointestinal cancer (3 patients, 17.6%). The ir-h-AE included 7 patients (41.2%) with warm AIHA, 4 (23.5%) with ITP (1 had immune-related pancytopenia that resolved with ITP persisting), 3 (17.6%) with IRN, 1 with AA, 1 with CAD, and 1 with PRCA and mild ITP. All patients had received an ICI dose within 60 days of diagnosis (range 3-52 days, median 18 days). Only 1 patient had a concomitant chronic autoimmune disorder (antinuclear antibody-positive arthritis). Four patients (23.5%) were receiving chemotherapy. Sixteen patients (94.1%) required treatment and received corticosteroids. Eight out of 15 evaluable patients (53.3%) responded to corticosteroids only. Another 4 responders (26.7%) required additional therapies including intravenous immunoglobulins (IVIG) (4, 23.5%) and/or rituximab (4, 23.5%). Overall response rate was 71.4% for AIHA and 100% for IRN. ITP was likely underrepresented in our cohort, and the response rate of 66.7% is likely lower than the response rate in clinical practice. This could be related to the fact that many mild thrombocytopenia cases are not further evaluated in clinical practice. None of our patients died from the sequelae of an ir-h-AE. Two patients (11.8%) died within 30 days of ir-h-AE diagnosis (disseminated intravascular coagulation likely due to the underlying malignancy and sepsis from bacterial pneumonia). At the time of ir-h-AE diagnosis, the malignancy was showing evidence of response in 9 patients (52.9%), progression in 6 patients (35.3%), and stability in 2 patients (11.8%). ICI therapy was permanently discontinued in 9 patients (52.9%) and temporarily held in 6 patients (35.3%). Three of the 5 patients (60%), who were rechallenged with ICI therapy, had recurrence of the same ir-h-AE (AIHA) with adequate response to therapy. Non-hematologic irAE (7 patients, 41.2%) included 3 patients with hepatitis, 2 with thyroiditis, 2 with pneumonitis, 1 with colitis, and 1 with dermatitis. Conclusion Our clinical experience with ir-h-AE highlights the importance of exercising vigilance in assessing the hematologic parameters of patients receiving ICI therapy. While relatively rare, ir-h-AE may impact the clinical course of patients with cancer and their eligibility for therapies that have the potential of offering durable control of the underlying malignancy. ir-h-AE respond to classical therapies including corticosteroids, IVIG, and rituximab. Disclosures Block: Merck: Research Funding; Bristol-Myers Squibb: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Marker Therapeutics: Research Funding; Transgene: Research Funding; Immune Design: Research Funding. Kottschade:Bristol-Myers Squibb: Consultancy, Research Funding.

e22124 Background: Therapeutic anti-cancer vaccine strategies have been effective in a broad range of preclinical tumor models, but clinical trials of vaccines in metastatic cancer patients have failed to show clinical benefit. We have previously shown that patients with stage IV melanoma have systemic immunosuppression including elevated plasma levels of immunosuppressive cytokines and impaired DTH responses to recall antigens. Patients with stage IV melanoma also have elevated circulating levels of the vascular growth factors vascular endothelial growth factor A (VEGF A) and placental growth factor (PlGF). Based on these observations, we have hypothesized that vascular growth factors such as VEGF and PlGF mediate systemic immunosuppression. Methods: FVB mice with established ANV6 transplantable breast tumors were bled, and plasma samples were assayed for VEGF, PlGF, and interleukin (IL)-10. Splenocytes taken from tumor-bearing mice were stimulated via the T cell receptor (TCR), and interferon gamma (IFN) production was measured. Splenocytes from normal mice were stimulated in the presence or absence of VEGF; IFN production was measured. Results: Compared with age- and sex-matched controls, tumor-bearing mice had elevated plasma levels of VEGF, PlGF, and the immunosuppressive cytokine IL-10 (see table ). Furthermore, splenocytes from tumor-bearing mice produced less IFN upon TCR stimulation than did splenocytes from control mice. Finally, normal mouse splenocytes produced less IFN when stimulated in the presence of VEGF than in its absence (70.2 ± 37.2 vs. 260.0 ± 130.9 pg/ml). Conclusions: We have shown that mice with advanced tumors exhibit both elevated levels of vascular growth factors and systemic immune inhibition. We have also shown that VEGF leads to impairment of immune function in normal splenocytes. Taken together, these results suggest that excess vascular growth factors may mediate immunosuppression in animals with advanced tumors, which may in turn impair anti-tumor vaccine efficacy. [Table: see text] No significant financial relationships to disclose.