Kottschade, Lisa A.

9503 Background: Neoadjuvant ± adjuvant immunotherapy improves event-free survival relative to adjuvant immunotherapy alone for patients with high-risk resectable stage III melanoma. However, the optimal regimen balancing efficacy and tolerability is not known. T-cell immunoglobulin and ITIM domain (TIGIT) is a promising immune checkpoint but its therapeutic potential in stage III melanoma is underexplored. Methods: In this phase II trial, patients with resectable, macroscopic stage III melanoma received four 21-day neoadjuvant cycles of 1200mg IV atezolizumab (atezo, anti-PD-L1) + 600mg IV tiragolumab (tira, anti-TIGIT), followed by therapeutic lymph node dissection (TLND) and eight 21-day adjuvant cycles of 1200mg IV atezo. Primary endpoints were pathologic response (of all patients initiating neoadjuvant therapy) and recurrence-free survival (RFS) from the time of TLND in patients who were operated on per protocol and received adjuvant therapy. Secondary endpoint was adverse events (AEs); exploratory endpoints included event-free survival (EFS) and distant metastasis-free survival (DMFS). Results: Thirty-four patients, median age 59 years, were accrued and initiated neoadjuvant atezo/tira. 76.5% had >1 metastatic lymph node involved at baseline and 73.5% presented with Stage IIIC disease. All 34 patients were evaluable for AEs, pathologic response and EFS. Four patients were diagnosed with metastatic disease during neoadjuvant treatment, while 30 had TLND per protocol and 28 received adjuvant treatment and were evaluable for RFS and DMFS. Major pathologic responses (MPR, ≤10% viable tumor) were observed in 16/34 patients (47.1%, Table). With 19.9 months median follow-up from registration, 12-month EFS was 72.0% (95% CI 57.9 to 89.5%). With 16 months median follow-up from operation, 12-month RFS was 73.3% (n=28, 95% CI 56.9 to 94.5%), while 12-month DMFS was 86.0% (n=28, 95% CI 72.2 to 100%). In the 16 patients with an MPR, 2 did not receive adjuvant treatment and were followed for 33.3 and 10.8 months without recurrence/death. In the remaining 14 patients, 12-month RFS and 12-month DMFS were both 91.7% (95% CI 77.3 to 100%). 5 patients (14.7%) experienced any grade 3+ AE with 2 (5.9%) at least possibly related to the neoadjuvant regimen. Conclusions: Among patients with high-risk resectable stage III melanoma, neoadjuvant atezo/tira was a promising regimen with a favorable safety profile and warrants further study. Identification of predictive biomarkers will allow for optimization of neoadjuvant therapy for individual patients. Clinical trial information: NCT03554083 . Pathologic response. N=34 Major Pathologic Response 16 (47.1%) Pathologic complete response (no viable tumor) 13 (38.2%) Near-pathologic complete response (0.1−10% viable tumor) 3 (8.8%) Pathologic partial response (>10.0−50% viable tumor) 2 (5.9%) Pathologic non-response (>50% viable tumor) 12 (35.3%) No per protocol operation 4 (11.8%)

Background Neoadjuvant treatment has become standard for patients with high-risk operable stage III melanoma, but the optimal regimen is unknown. Targeted therapy approaches yield high pathological response rates, while immunotherapy regimens show favorable recurrence-free survival (RFS). NeoACTIVATE was designed to address whether a neoadjuvant combination of both targeted therapy and immunotherapy might leverage the benefits of each. Methods We tested neoadjuvant treatment with 12 weeks of vemurafenib, cobimetinib, and atezolizumab for patients with BRAF-mutated (BRAFm) melanoma (cohort A) and cobimetinib and atezolizumab for patients with BRAF-wild-type (BRAFwt) melanoma (cohort B), regimens which we have shown generate a substantial major pathological response. After therapeutic lymph node dissection, patients received 24 weeks of adjuvant atezolizumab. Here, we report survival outcomes and their association with biomarkers assayed among the gut microbiome and peripheral blood immune subsets. Results With 49 months median follow-up, the median RFS was not reached for cohort A and was 40.8 months for cohort B. At 24 months after operation, 2 of 14 cohort A patients and 4 of 13 cohort B patients had experienced distant relapse. Key findings from correlative analyses included diversity, taxonomic and functional metagenomic gut microbiome signals associated with distant metastasis-free survival at 2 years. Notably, we observed a strong correlation between low microbial arginine biosynthesis (required for T-cell activation and effector function) and early distant recurrence (p=0.0005), which correlated with taxonomic differential abundance findings. Peripheral blood immune monitoring revealed increased double-positive (CD4+CD8+) T cells in patients with early recurrence. Conclusions Neoadjuvant treatment with cobimetinib and atezolizumab±vemurafenib was associated with a low rate of distant metastasis in patients with high-risk stage III melanoma. Freedom from early distant metastasis was highly associated with taxonomic differences in gut microbiome structure and with functional pathway alterations known to modulate T cell immunity. Identification of predictive biomarkers will permit optimization of neoadjuvant therapy regimens for individual patients. Trial registration number NCT03554083.

Abstract Introduction: Immune checkpoint inhibitors (ICI) are an essential systemic therapy for advanced melanoma. However, most melanomas develop resistance to ICI. Tumor-derived soluble PD-L1 (sPD-L1) and other soluble immunosuppressive factors drive checkpoint inhibitor resistance and correlate with inferior survival. We previously showed that therapeutic plasma exchange (TPE) removes sPD-L1 from circulation. Thus, we hypothesized that TPE-mediated removal of sPD-L1 and other immunosuppressive factors could overcome immunotherapy resistance in refractory melanoma. Methods: In this clinical trial (NCT04581382), we prospectively enrolled eighteen (18) patients with widely metastatic melanoma with progression despite anti-PD-1 ICI and elevated sPD-L1 by ELISA (≥1.7ng/mL). Each patient received radiotherapy to between one and three metastatic lesions (at least two unirradiated lesions) followed by three TPE sessions on consecutive days and re-challenge with checkpoint inhibitor. The primary safety and efficacy endpoints of the study were adverse events (AEs) and sPD-L1 reduction by TPE, respectively. Secondary endpoints included RECIST-based response in unirradiated lesions and overall survival. Correlative studies included kinetics of sPD-L1 and soluble immonsuppressive factors and dynamics of peripheral immune cell phenotypes. Results: Mean age was 62 (SD 13) and seven of eighteen (39%) were female. Mean baseline sPD-L1 was 26.31 ng/mL (40.01). The treatment was well-tolerated with one (6%) patient with grade 3 and 4 adverse events from a central line infection after TPE. Levels of sPD-L1 were significantly reduced by TPE (mean 80.2% reduction, p<0.0001). Two patients (11.1%) experienced complete response (CR), one (5.6%) partial response, three (16.7%) stable disease, and 12 (66.7%) progressive disease. In one case, immunotherapy was discontinued after two years due to no detectable lesions. Changes in tumor-reactive (TTR) GZMB+/CX3CR1+/CD11ahigh and other peripheral immune cell populations predicted overall survival in this cohort. In addition to sPD-L1, other soluble mediators of ICI resistance were also reduced by TPE and predicted overall survival in this cohort. Summary/Conclusion: sPD-L1 and other soluble immunoregulatory signaling molecules are important mediators of ICI resistance. SBRT and TPE can resensitize ICI-refractory melanoma by removing these factors. Patients with persistently elevated or rapid rebound of sPD-L1 following TPE experienced poor response and overall survival. Serial monitoring of sPD-L1 may predict response to ICI and multiple courses of TPE may be necessary. Our findings may apply in other ICI-resistant cancers with elevated sPD-L1. ClinicalTrials.gov registration: NCT04581382, ReCIPE-M1 (Rescuing Cancer Immunotherapy with Plasma Exchange in Melanoma 1).

Melanoma is the deadliest form of skin cancer. The median age at diagnosis is 66. While most patients are treated with immunotherapy, the use of targeted therapy is a valid alternative for patients whose tumors harbor a BRAF or c-KIT driver mutation. These agents, while effective, come with a variety of side effects which limit their use, especially in older patients. We sought to assess the efficacy and toxicity of these agents in older melanoma patients. Melanoma patients over 65 treated with BRAF/MEK or c-KIT inhibitors were retrospectively identified, and their data were analyzed for treatment efficacy and toxicity. All data were compared using the Chi-square test for categorical comparisons and the Kruskal–Wallis method for median comparisons. One hundred and sixteen patients were identified. One hundred and six patients were treated with BRAF/MEK inhibitors. The assessed response rate (RR) was 83% and was comparable across different subgroups, including advanced line patients and those with a more aggressive disease. The median progression free survival (PFS) was 7.9 months, and the median overall survival (OS) was 15.7 months. Twenty-seven percent experienced grade 3–4 toxicity leading to a 24% treatment discontinuation rate. Another 10 patients were treated with the c-KIT inhibitor imatinib, for whom the assessed RR was 55%. The median PFS was 4.3 months, and the median OS was 22.6 months. Forty percent needed dose reductions, yet none had to stop treatment due to adverse effects. The use of targeted therapy in older patients is effective yet challenging due to toxicity. Deploying mitigation strategies can help maximizing their usefulness.

e21554 Background: Pregnancy associated melanoma (PAM) occurs in 1% of female patients with melanoma and affects 1 in 2200 pregnancies. Antepartum evaluation of melanoma must incorporate both maternal and fetal factors, and currently there is lack of standardization. Our study aimed to review the incidence of antepartum melanoma at our institution and highlight patterns in management and treatment during this high-risk scenario. Methods: After IRB approval, the Mayo Clinic electronic medical record was searched with key words “melanoma” and “pregnancy”. 25 patients with melanoma during pregnancy were identified from 1987-2023. 6 patients were excluded as skin changes noted during pregnancy were not formally diagnosed as melanoma until after delivery. Abstracted data included demographic information, disease characteristics, staging (per AJCC guidelines at time of diagnosis), and clinical outcomes. Survival data were calculated. Results: 19 patients were included. Diagnosis occurred at an average maternal age of 30 years (range 24-38 years) and a mean gestational age of 20 weeks (range 6-35 weeks). All patients had a term delivery. 4 patients underwent labor induction at 37 weeks for staging/treatment. 60% of patients had a delay in imaging or treatment attributed to pregnancy, including 1 patient who was upstaged with metastatic disease based on postpartum imaging. 82% of stage I-III patients underwent wide local excision during pregnancy; however, 35% of sentinel lymph node sampling was delayed until postpartum. 3 stage II/III patients received adjuvant therapy (interferon or sargramostim) after delivery. Adjuvant immunotherapy was discussed with 2 patients in the postpartum period but ultimately not given due to the time lapse between surgery and delivery. 1 patient with stage IV disease diagnosed at a gestational age of 20 weeks was evaluated with MRI PET scan then treated with vemurafenib monotherapy during pregnancy. Workup and outcomes were reviewed by stage (Table 1). 7 of 19 patients had subsequent pregnancies, and 1 had recurrence of melanoma during a second pregnancy (stage II followed by stage IV). Due to a low number of censoring events, median progression free survival and overall survival were not reached. Conclusions: Melanoma diagnosed during pregnancy can be safely and effectively staged with sentinel lymph node surgery, MRI imaging (PET-MRI vs standard), and CT imaging with shielding without a need for early induction of labor nor a delay in cancer care. Furthermore, we report a patient with stage IV disease treated with vemurafenib during and immunotherapy after pregnancy, indicating that treating stage IV PAM with systemic therapy is a consideration. [Table: see text]

e23270 Background: Melanoma is the most lethal form of skin cancer which have seen drastic improvement in patient survival over the last decade. BRAF is the most common driver mutation in melanoma, seen in ≈50% of all patients (≈30% of patients > 65). The use of BRAF & MEK inhibitors yields high response rates, though it is limited by toxicity and development of acquired resistance. Acknowledging these limitations, we aimed at assessing the efficacy and toxicity of these agents in melanoma patients > 65. Methods: We identified electronic medical records of all melanoma patients > 65 that were treated with BRAF & MEK inhibitors at our institution over the years 2017-2023. Data was retrospectively collected including demographics, disease characteristics, treatment given, response patterns and toxicity. Results: 106 patients were identified. The median age was 71 (65-89), 55% were males. The median follow up was 28.9 months. 32 (30%) patients were treated at first line, 58 (55%) at second line and 16 (15%) at third line. 88 (83%) evaluable patients received treatment for unresectable/metastatic disease of which 84% had an objective response (60% partial response, 24% complete response). Response rate (RR) was 82%, 85% and 87% for first, second and third line respectively. RR was 86% for patients with an increased serum lactate dehydrogenase. 33% of patients had active central nervous system (CNS) metastases at treatment initiation, for whom the systemic RR was 80% and the CNS RR was 39%. The median progression free survival (PFS) was 7.9 months, with a PFS of 6, 8.3 and 13.4 months for first, second and third line respectively. The median PFS was 5.7 months for patients with active CNS disease. The median overall survival (OS) from treatment initiation was 15.7 months (12.5, 14.5, 31.9 for first, second & third line respectively). The median OS for patients with CNS disease was 9.8 months. 16 patients were treated in the adjuvant setting, of which 6 (37%) finished treatment as planned, 3 stopped due to disease progression (19%) and 6 stopped due to toxicity (37%). 88% of patients experienced adverse events (AEs) of any grade, with 27% having grade 3-4 toxicity. There were no grade 5 toxicities reported. 36% of patients experienced one AE, while 52% experienced two or more. 21% of patients stopped treatment due to toxicity, 28% needed a dose reduction and 20% changed to different BRAF/MEK inhibitors. 10% of patients needed systemic corticosteroids to treat AEs. The most common toxicities seen were fever (30%), fatigue (30%), skin rash (22%), elevated liver function tests (20%), arthralgia/myalgia (15%), nausea (14%) and diarrhea (11%). 7% had decrease in cardiac ejection fraction with one grade 3 leading to treatment discontinuation. Conclusions: Treatment with BRAF & MEK inhibitors is challenging in older patients, with a high prevalence of toxicity leading to treatment modifications and discontinuation. Efficacy seems to be the same as in the general population.

PURPOSE Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, yet their use is associated with immune-related adverse events (irAEs). Estimating the prevalence and patient impact of these irAEs in the real-world data setting is critical for characterizing the benefit/risk profile of ICI therapies beyond the clinical trial population. Diagnosis codes, such as International Classification of Diseases codes, do not comprehensively illustrate a patient's care journey and offer no insight into drug-irAE causality. This study aims to capture the relationship between ICIs and irAEs more accurately by using augmented curation (AC), a natural language processing–based innovation, on unstructured data in electronic health records. METHODS In a cohort of 9,290 patients treated with ICIs at Mayo Clinic from 2005 to 2021, we compared the prevalence of irAEs using diagnosis codes and AC models, which classify drug-irAE pairs in clinical notes with implied textual causality. Four illustrative irAEs with high patient impact—myocarditis, encephalitis, pneumonitis, and severe cutaneous adverse reactions, abbreviated as MEPS—were analyzed using corticosteroid administration and ICI discontinuation as proxies of severity. RESULTS For MEPS, only 70% (n = 118) of patients found by AC were also identified by diagnosis codes. Using AC models, patients with MEPS received corticosteroids for their respective irAE 82% of the time and permanently discontinued the ICI because of the irAE 35.9% (n = 115) of the time. CONCLUSION Overall, AC models enabled more accurate identification and assessment of patient impact of ICI-induced irAEs not found using diagnosis codes, demonstrating a novel and more efficient strategy to assess real-world clinical outcomes in patients treated with ICIs.

Abstract Purpose: AB160 is a 160-nm nano-immunoconjugate consisting of nab-paclitaxel (ABX) nanoparticles noncovalently coated with bevacizumab (BEV) for targeted delivery into tissues expressing high levels of VEGF. Preclinical data showed that AB160 resulted in greater tumor targeting and tumor inhibition compared with sequential treatment with ABX then BEV. Given individual drug activity, we investigated the safety and toxicity of AB160 in patients with gynecologic cancers. Patients and Methods: A 3+3 phase I trial was conducted with three potential dose levels in patients with previously treated endometrial, cervical, and platinum-resistant ovarian cancer to ascertain the recommended phase II dose (RP2D). AB160 was administered intravenously on days 1, 8, and 15 of a 28-day cycle (ABX 75–175 mg/m2, BEV 30–70 mg/m2). Pharmacokinetic analyses were performed. Results: No dose-limiting toxicities (DLT) were seen among the three dose levels tested. Grade 3/4 toxicities included neutropenia, thromboembolic events, and leukopenia. DL2 (ABX 150 mg/m2, BEV 60 mg/m2) was chosen as the RP2D. Seven of the 19 patients with measurable disease (36.8%) had confirmed partial responses (95% confidence interval, 16.3%–61.6%). Pharmacokinetic analyses demonstrated that AB160 allowed 50% higher paclitaxel dosing and that paclitaxel clearance mirrored that of therapeutic antibodies. Conclusions: The safety profile and clinical activity of AB160 supports further clinical testing in patients with gynecologic cancers; the RP2D is DL2 (ABX 150 mg/m2, BEV 60 mg/m2).

ABSTRACT Despite ocular adverse events from immune checkpoint inhibitors being uncommon, they are still important complications to be aware of. We present the case of metastatic melanoma on ipilimumab/nivolumab in a patient who developed immunotherapy complications with delayed diagnosis because the only presenting symptom was unilateral ptosis. We reviewed the literature for relevant and important ocular and neurological complications of immune checkpoint inhibitors.