Immune-mediated Adverse Events Research Articles

Reprogramming the tumor immune microenvironment using engineered dual-drug loaded Salmonella

Synergistic combinations of immunotherapeutic agents can improve the performance of anti-cancer therapies but may lead to immune-mediated adverse effects. These side-effects can be overcome by using a tumor-specific delivery system. Here, we report a method of targeted immunotherapy using an attenuated Salmonella typhimurium (SAM-FC) engineered to release dual payloads: cytolysin A (ClyA), a cytolytic anti-cancer agent, and Vibrio vulnificus flagellin B (FlaB), a potent inducer of anti-tumor innate immunity. Localized secretion of ClyA from SAM-FC induces immunogenic cancer cell death and promotes release of tumor-specific antigens and damage-associated molecular patterns, which establish long-term antitumor memory. Localized secretion of FlaB promotes phenotypic and functional remodeling of intratumoral macrophages that markedly inhibits tumor metastasis in mice bearing tumors of mouse and human origin. Both primary and metastatic tumors from bacteria-treated female mice are characterized by massive infiltration of anti-tumorigenic innate immune cells and activated tumor-specific effector/memory T cells; however, the percentage of immunosuppressive cells is low. Here, we show that SAM-FC induces functional reprogramming of the tumor immune microenvironment by activating both the innate and adaptive arms of the immune system and can be used for targeted delivery of multiple immunotherapeutic payloads for the establishment of potent and long-lasting antitumor immunity.

Gender medicine in lung diseases

Gender-specific differences in the diagnostics and treatment must be considered for various lung diseases. In the case of pneumothorax, in addition to differences in etiology there are also relevant differences in treatment and recurrence rates between men and women. For example, to achieve low recurrence rates catamenial pneumothorax requires interdisciplinary collaboration with gynecology. The incidence of lung cancer has equalized in recent years and in addition, various gender-specific prognostic factors have become relevant. Several meta-analyses have identified female gender as apositive prognostic factor for lung cancer, in addition to the higher prevalence of various driver mutations in women. In current trials of multimodal treatment for lung cancer, gender differences in tolerability and patient outcome are already apparent. In subgroup analyses better event-free survival was observed in women, although immune-mediated adverse events were more common in women.

Model-based population pharmacokinetic and exposure response analyses for safety and efficacy of nivolumab as adjuvant treatment in subjects with resected oesophageal or gastroesophageal junction cancer.

Nivolumab is approved as adjuvant treatment in subjects with resected oesophageal or gastroesophageal junction cancer (EC/GEJC) based on results from the pivotal CheckMate 577 trial. We present a model-based clinical pharmacology profiling and benefit-risk assessment of nivolumab as adjuvant treatment in subjects with resected EC/GEJC supporting a less frequent dosing regimen. Population pharmacokinetic (popPK) analysis was conducted to characterize nivolumab pharmacokinetics (PK) using clinical data from 1493 subjects from seven monotherapy clinical studies across multiple solid tumours. The exposure-response (E-R) analyses included data from 756 patients from CheckMate 577. E-R relationships for efficacy and safety were characterized by evaluating the relationship between nivolumab exposure and disease-free survival (DFS) for efficacy; and time to first occurrence of Grade ≥2 immune-mediated adverse events (Gr2 + IMAEs) for safety. Nivolumab exposure was found to be associated with both DFS and risk of Gr2 + IMAEs. However, the hazard ratios (HRs) (95% confidence interval [CI]) at the 5th and 95th percentiles of nivolumab exposure were similar for DFS and Gr2 + IMAEs, indicating flat E-R relationships within the exposure range produced by the studied regimen. Model-predicted probability of DFS and Gr2 + IMAEs were similar between the two regimens of 240 mg every 2weeks or 480 mg every 4weeks for 16 weeks followed by 480 mg Q4W up to 1year. The analyses demonstrated a flat E-R relationship over the range of exposures produced by the studied regimen and supported the approval of an alternative dosing regimen with less frequent dosing in patients with adjuvant EC/GEJC.

Flow cytometry vs conventional methods for the evaluation of anti-PF4/heparin antibodies: a single center study.

Aim: Heparin-induced thrombocytopenia (HIT) is a rare, life-threatening, immune-mediated adverse effect of heparin administration. This study compares frequently used laboratory assays in terms of their effectiveness in HIT diagnosis. Materials & methods: Fifty patients with suspected HIT were tested by gel immunoassay and solid phase PF4/heparin antibody ELISA. On positive results, platelet activation markers P-selectin and Annexin V were assayed using flow cytometry. Results: Thirty/50 patients were negative for both immunoassays. Flow cytometry was performed in the 20 immunoassay positive patients. Platelet activation was observed in 7/20 in the presence of low heparin concentration (0.2IU/ml). Conclusion: The results are in accordance with the currently available literature and flow cytometry seems a promising alternative in HIT laboratory investigation.

PD-1 regulation of pathogenic IL-17-secreting γδ T cells in experimental autoimmune encephalomyelitis.

The PD-1-PD-L1 immune checkpoint helps to maintain self-tolerance and prevent the development of autoimmune diseases. Immune checkpoint inhibitors are successful immunotherapeutics for several cancers, but responding patients can develop immune-mediated adverse events. It is well established that PD-1 regulates CD4 and CD8 T-cell responses, but its role in controlling the activation of pathogenic γδ T cells is less clear. Here we examined the role of PD-1 in regulating γδ T cells in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. We found that PD-1 was highly expressed on CD27- Vγ4 γδ T cells in the lymph node (LN) and CNS of mice with EAE. Treatment of mice with anti-PD-1 significantly augmented IL-17A-producing CD27- Vγ4 γδ T cells in the LN and CNS and enhanced the severity of EAE. The exacerbating effect of anti-PD-1 on EAE was lost in Tcrd-/- mice. Conversely, ligation of PD-1 suppressed Il17a and Rorc gene expression and IL-17A production by purified Vγ4 γδ T cells stimulated via the TCR, but not with IL-1β and IL-23. Our study demonstrates that PD-1 regulates TCR-activated CD27- Vγ4 γδ T cells, but that cytokine-activated IL-17A producing γδ T cells escape the regulatory effects of the PD-1-PD-L1 pathway.

Efficacy and side effects of pembrolizumab plus chemotherapy vs. chemotherapy alone in patients with advanced gastric or gastroesophageal junction adenocarcinoma: A meta‑analysis.

Recently, the treatment plan of pembrolizumab plus chemotherapy was regarded as a promising treatment for patients with advanced gastric cancer or gastroesophageal junction adenocarcinoma (GC/GEJC). However, the efficacy and side effects of pembrolizumab plus chemotherapy still lack evidence-based medical evidence to support. Therefore, a meta-analysis was conducted to evaluate the hot issue. By searching PubMed, EMBASE, Cochrane Library, Web of Science, any randomized clinical studies of pembrolizumab plus chemotherapy versus chemotherapy in patients with advanced GC/GEJC met the inclusion criteria were included. The quality of the literature was evaluated and the data was extracted. A correlative software was also used to analyze the data and to draw a conclusion. After screening 14,015 studies, four studies were eligible for the meta-analysis. Compared with chemotherapy alone group, the overall survival (OS) rate was significantly longer. In programmed cell death ligand 1 (PD-L1) combined positive score (CPS) ≥1 subgroup and PD-L1 CPS ≥10 subgroup analyses, the results showed that the response rate (RR) and complete response rate (CR) were both higher in pembrolizumab plus chemotherapy group compared with chemotherapy alone group. There were not significant differences in the CR, the treatment-related adverse events, succumbed to drug-related events and succumbed to immune-mediated events between the two groups. However, the effect events such as the treatment-related adverse events led to discontinuation, the 3-5 treatment-related adverse events and the immune-mediated adverse events and infusion reactions were more common in pembrolizumab plus chemotherapy group. In conclusion, the current meta-analysis revealed that, in treating advanced GC/GEJC, pembrolizumab plus chemotherapy had improved therapeutic efficacies than chemotherapy alone, as evidenced by the significantly longer OS. Furthermore, the patients in PD-L1 CPS ≥1 subgroup and PD-L1 CPS ≥10 subgroup appeared to benefit from pembrolizumab plus chemotherapy treatment because of higher RR and CR. However, side effects such as the treatment-related adverse events leading to discontinuation, the 3-5 treatment-related adverse events, and immune-mediated adverse events and infusion reactions deserved more attention.

An overview and single-arm meta-analysis of immune-mediated adverse events following COVID-19 vaccination.

We conducted an overview to assess immune adverse effects associated with the COVID-19 vaccine, guiding safer choices and providing evidence-based information to clinicians. Forty-three studies on adverse effects of vaccines were reviewed from PubMed, Embase, and Web of Science. Single-arm meta-analyses estimated summary effects, incidence, presentation, etc. An overview using single-arm meta-analysis and reported the findings following the guidelines outlined in the 'Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) specifically focusing on myocarditis and thrombosis. After screening 2,591 articles, 42 studies met the inclusion criteria. Methodological quality was evaluated using AMSTAR 2. Disagreements were resolved via consensus. Data analysis utilized a random-effects model in R software to estimate incidence rates of selected adverse events. After removing 1,198 duplicates and screening out irrelevant articles from a total of 2,591, we included 42 studies. Adverse reactions to vaccinations include myocarditis, thrombosis, skin reactions, GBS, etc. thrombosis and myocarditis are the most dangerous diseases associated with vaccination. Myocarditis occurred in 6% of Vector vaccine recipients, compared to 61% of mRNA vaccine recipients. Thrombosis was more common after Vector vaccination (91%) than after mRNA vaccination (9%). Furthermore, eight studies conducted anti-PF4 antibody tests and yielded a positivity rate of 67%. Meta-analysis showed that among all patients with Vaccine-induced Thrombotic Thrombocytopenia, cerebral venous sinus thrombosis occurred in 66%, and intracranial hemorrhage occurred in 43%. The rates of deep vein thrombosis and pulmonary thromboembolism in vaccinated patients were 13% and 23%, respectively, with a pooled case fatality rate of 30%. The results of this overview indicate the majority of adverse reactions are self-limiting and require minimal intervention, while rare occurrences such as myocarditis and thrombosis pose a potentially fatal threat.

Evaluating gut microbiome as a biomarker of pathological complete response in patients with early locally advanced triple negative breast cancer (LA TNBC): A pilot study.

593 Background: It has previously been shown that microbial metabolic pathways are differentially activated in immunotherapy resistance, hence can serve as potential biomarker as well as target for therapeutic intervention. With the advent of Immune Checkpoint Blockers (ICB) in the neoadjuvant (NA) setting of locally advanced (LA) TNBC, we hypothesized that similar microbial metabolite mediated resistance may be at play. We are presenting data demonstrating differences in microbiome and metabolites in these patients. Methods: 28 patients who received NA pembrolizumab and chemotherapyfor LA TNBC were identified at Moffitt Cancer Center and Tampa General Hospital between February 2022 to October 2023. Blood and stool samples were collected at therapy initiation, at completion of neoadjuvant treatment and/or when the patients developed grade 3 or higher toxicity to therapy. We evaluated stool metagenomics and untargeted stool/plasma metabolomics as correlatives. Patient characteristics were as follows: 21 Caucasian, 3 African-American, 2 Hispanic, 2 unknown, median age 51 years, median body mass index (BMI) 28.5 kg/m2. 17 patients had stage II, while 11 patients had stage III TNBC. Results: Response was assessed in 27 patients, of which 11 had pCR (ypT0/is ypN0) while 16 had residual disease (RD). 1 patient progressed, while on NA therapy, while 8 patients developed grade 3-4 immune related adverse events leading to treatment discontinuation and death in one patient. We conducted shallow shotgun metagenomic sequencing and untargeted metabolomic profiling on pre and post treatment fecal and plasma samples respectively to identify gut microbial diversity, composition and differentially abundant metabolites associated with pCR.There wasno difference in alpha and beta diversity; however significant enrichment of microbiota with genus Akkermansia HR 0.04, p 0.03 was noted in those with pCR. We observed higher abundance of tryptophan metabolizing clostridium species HR 50541, p <0.001, along with differential activation of microbial tryptophan pathway in those with residual disease, specifically higher abundance of hydroxyindole acetic acid HR 1.54 P<0.005, indole propionic acid HR 1.75 p 0.05 and indole butyric acid HR 1.86 p 0.04. Conclusions: To our knowledge this is the first analysis of differences in the microbiome and microbial metabolism in patients with LA TNBC treated with NA ICB. Despite being a small study, it shows a more aggressive disease pattern with higher RD than noted in KEYNOTE 522 and shows significant concern for serious immune mediated adverse effects. This highlights the importance of biomarkers to stratify patients most likely to benefit from ICB. Enrichment of microbiota and immunosuppressive tryptophan metabolites were associated with pCR and should be validated in large studies as biomarker of response to NA ICB in TNBC.

Preoperative (neoadjuvant) therapy with tislelizumab for locally advanced colorectal cancer with high microsatellite instability or deficient mismatch repair: An open-label, single-arm, multicenter phase II study.

3599 Background: Tislelizumab (TIS), an anti-programmed cell death protein 1 (PD-1) antibody, demonstrated improved anti-tumor response and tolerable safety in patients (pts) with previously treated, locally advanced unresectable or metastatic microsatellite instability high/deficient mismatch repair (MSI-H/dMMR) solid tumors, including colorectal cancer (CRC; NCT03736889). Recent studies of other anti-PD-1 antibodies indicate potential clinical benefit of neoadjuvant anti-PD-1 therapy in pts with resectable MSI-H/dMMR CRC. Here, we report efficacy and safety outcomes of neoadjuvant TIS from a multicenter phase II trial (NCT05116085) in this population. Methods: Pts aged ≥18 years with stage II/III MSI-H/dMMR CRC, ECOG PS 0-1, evaluable disease per RECIST v1.1, and eligible for R0 (complete) resection were enrolled. Pts received TIS 200 mg IV every 3 weeks for 3 cycles followed by surgical resection within 10 weeks of first TIS dose. The primary endpoint was major pathological response (MPR) rate (proportion of pts with ≤10% residual viable tumor in the surgically resected primary tumor). Secondary endpoints included pathological complete response (pCR) rate (proportion of pts with absence of residual tumor in the surgically resected specimen), and safety. The R0 resection rate was an exploratory endpoint. Results: Overall, 33 pts were enrolled across eight sites in China. The median age of enrolled pts was 52.0 years (range: 23-84), 14 (42.4%) pts were male. Ten (30.3%) pts had rectal cancer and 23 (69.7%) colon cancer. At study entry, clinical tumor (T) stage was reported as T2, T3, and T4 in 1 (3.0%), 7 (21.2%), and 25 (75.8%) pts, respectively, and node (N) stage as N0, N1, and N2 in 6 (18.2%), 14 (42.4%), and 13 (39.4%) pts, respectively. All pts had a metastasis (M) stage of M0. A total of 29 (87.9%) pts underwent surgery and were evaluable for efficacy endpoints. Surgery was not performed in 4 pts, 3 of whom were managed non-operatively (1 pt had progressive disease). MPR and pCR rates were 89.7% and 62.1%, respectively (Table). Any-grade and grade ≥3 TIS-related adverse events (TRAEs) were reported in 20 (60.6%) and 1 (3.0%) pts, respectively. Two (6.1%) pts experienced serious TRAEs; no TRAEs led to death or surgery cancellation. One pt (3.0%) experienced a TRAE (grade 2 hypothyroidism) leading to surgery delay. No grade ≥3 or serious TIS-related surgery-relevant adverse events were reported. Immune-mediated adverse events were reported in 10 (30.3%) pts (all grade 1-2). Conclusions: Neoadjuvant TIS was associated with high MPR and pCR rates and an acceptable safety profile, and did not compromise surgery in pts with resectable MSI-H/dMMR CRC. Clinical trial information: NCT05116085 . [Table: see text]

Early detection of side effects in patients with metastatic melanoma receiving immune checkpoint inhibitors by investigation of CD8+ immune infiltrate with [89Zr] crefmirlimab berdoxam PET.

TPS9601 Background: Immune checkpoint inhibitors (ICI) improved outcomes of patients (pts) with advanced melanoma. Nevertheless, a significant number have immune-mediated adverse event (iAE). Due to the impact on quality of life and other therapeutic options, early identification of pts with increased risk of iAE is needed. CD8 immuno-PET with [89Zr] crefmirlimab berdoxam (Zr-Df-IAB22M2C) has shown to be a specific tool to visualize CD8+ T cells mediating both anti-tumor immune response and inflammatory adverse effects rendering this an innovative evaluation method in the field of immuno-oncology. Methods: Trial design: Open-label, single-arm, single center study to determine if CD8+ T-cell infiltration evaluated by immune-PET provides diagnostic gain in early detection of severe iAE. Pts with irresectable stage III/IV melanoma receiving nivolumab + ipilimumab (NIVO+IPI) may be included. Primary objective: Feasibility of early detection of iAE by semiquantitative assessment of CD8+ T-cell infiltration using immune-PET. Secondary objectives: 1) Prediction of iAE using immuno-PET for semiquantitative assessment of CD8+ T-cell infiltration; 2) Correlation between CD8+ T-cell infiltration in metastasis and lymphoid organs and response. Baseline Imaging. To assess glucose metabolism in metastases, primary and secondary lymphatic organs [18F] FDG PET/CT (60 min p.i. 1.5 MBq/KG/BW) is performed on a high sensitivity PET/CT with large field of view (Siemens Vision Quadra). Immediately after PET/CT data acquisition, pts are injected with [89Zr] crefmirlimab berdoxam (37 MBq ±20%) and undergo immuno-PET/CT 24 hours p.i. to detect CD8+ T-cells in metastases and lymphoid organs. NIVO+IPI is administered immediately after completion of [89Zr] crefmirlimab berdoxam-PET/CT. Blood samples are taken for immune cell composition analysis, activation state, proteomic investigation (cytokine/chemokines) as well as metabolic profile. Therapy Phase Imaging: Three weeks after first ICI cycle and before second cycle, follow-up PET/CT are performed with both radiotracers [18F]FDG and [89Zr] crefmirlimab berdoxam following the identical protocol described above. Clinical trial information: EudraCT number - 2021-004328-13 .

Hematologic malignancies in Li-Fraumeni syndrome.

10613 Background: Li-Fraumeni Syndrome (LFS) is a hereditary cancer predisposition syndrome caused by mutations in the tumor suppressor gene TP53. Since its discovery, a growing list of cancers have been described in association with LFS, predominantly solid tumors. However, hematologic malignancies (HMs) cumulatively account for 4-10% of cancer diagnoses in LFS. In this study, we present the largest series of HMs in families with LFS with detailed clinical courses. Methods: This was a two-center retrospective observational cohort study conducted at the University of Utah and the University of Wisconsin-Madison with IRB approval. Cancer genetics clinic registries were reviewed to identify all families with LFS who also had a confirmed diagnosis of a HM. To meet criteria for LFS, the patient had to have a confirmed germline pathologic or likely pathologic TP53 variant. Patients with a TP53 variant of unknown significance (VUS) were also included if they met classical LFS testing criteria. Data was gathered by manual chart review of both the families’ histories and electronic health records. Results: Among the 121 families identified with LFS, 35 (29%) families had one or more HM. Of these, 17 individuals from 16 families (13%) had confirmed germline TP53 mutations. The most frequent HMs found were acute lymphoblastic leukemia (ALL) (n=6), non-Hodgkin lymphoma (NHL) (n=5), myelodysplastic syndromes (MDS) (n=3), and chronic lymphocytic leukemia (CLL) (n=2). Acute myeloid leukemia (AML), Langerhans cell histiocytosis (LCH), and chronic myeloid leukemia (CML) were each diagnosed once. Most cases were identified in adulthood (n=12, 71%). Of the 19 total HMs, the minority (n=5, 26%) were diagnosed post-cytotoxic therapy and only six (35%) individuals had received a diagnosis of LFS prior to HM diagnosis. The MDS/AML cohort (n=4) all exhibited bi-allelic inactivation of TP53. Two of these four patients achieved long term survival after matched-unrelated donor (MUD) hematopoietic stem cell transplant (HSCT). All three patients who underwent MUD donor HSCT had immune-mediated adverse events. Conclusions: In this study we found a significantly higher incidence of HMs in LFS than previously described, with a predominance of lymphoid over myeloid malignancies. The majority of patients had excellent outcomes after standard of care therapy pointing towards more favorable outcomes for patients with LFS and HMs than previously reported. We also report several unusual immune-mediated adverse events in our patients indicating possible immunogenicity of some TP53 variants. Most patients did not have prior exposure to cytotoxic treatments and were diagnosed with the HM prior to their LFS diagnosis. We also show that 38% of individuals with an HM have multiple family members with an HM, consistent with a familial HM pattern. This underscores the importance of detailed family and personal histories in HM patients found to carry a somatic TP53 variant.

A phase 2, open-label, 2-cohort study to evaluate patient preference for nivolumab (NIVO) + relatlimab (RELA) fixed-dose combination (FDC) subcutaneous (SC) vs NIVO + RELA FDC intravenous (IV) and NIVO SC vs NIVO IV in participants with melanoma.

TPS9619 Background: The oncology burden on healthcare resources and patients increases as the number of individuals with cancer grows, necessitating treatment options offering improved convenience to patients. SC delivery of monoclonal antibodies in various cancer indications has previously been shown to be effective, well tolerated, and preferred by patients over IV infusion. In CheckMate 67T (NCT04810078), noninferiority of exposure (time-averaged serum concentration at Day 28 and trough serum concentration at steady state) and efficacy (objective response rate by BICR) were previously reported for NIVO SC 1200 mg + recombinant human hyaluronidase PH20 (rHuPH20) vs IV in patients with locally advanced/metastatic clear cell renal cell carcinoma. RELATIVITY-127 (NCT05625399) is ongoing to establish exposure noninferiority of NIVO + RELA + rHuPH20 FDC SC to IV in patients with previously untreated metastatic/unresectable melanoma. This phase 2, open-label study CA224-1044 (NCT06101134) assesses patient preference for NIVO SC or NIVO + RELA FDC SC vs IV formulations after transitioning from IV to SC in patients with melanoma and aims to further characterize the safety profile of immuno-oncology therapy during IV-to-SC switch. Methods: Cohort 1 includes adult patients with previously untreated stage III (unresectable) or stage IV (metastatic) melanoma who will receive NIVO + RELA FDC IV every 4 weeks (Q4W) for 2 cycles (28-day cycle) followed by NIVO + RELA + rHuPH20 FDC SC Q4W until disease progression, unacceptable toxicity, or a maximum total treatment duration of 2 years, whichever comes first. Cohort 2 includes adult patients with completely resected stage IIB/C, stage III or stage IV melanoma who will receive NIVO IV Q4W for 2 cycles (28-day cycle) followed by NIVO SC + rHuPH20 Q4W until disease recurrence, unacceptable toxicity, or a maximum total treatment duration of 1 year, whichever comes first. The primary endpoint is the proportion of participants preferring the SC route of administration based on question 7 of the Patient Experience and Preference Questionnaire after the Cycle 4 Day 1 dose. This question evaluates patient preference for IV or SC or no preference in treatment administration and was previously used in CheckMate 8KX. Secondary endpoints include safety outcomes such as adverse events (AEs), serious AEs, treatment-related AEs, AEs leading to discontinuation, immune-mediated AEs, other events of special interest, injection/infusion-related AEs, deaths, and laboratory abnormalities. Safety is assessed for IV period, SC period (8 weeks each) and overall study period. Exploratory endpoints include additional measures of patient experience and preference for IV vs SC. The study is recruiting to enroll 50 patients per cohort. Clinical trial information: NCT06101134 .

Long-term pooled safety analysis of tislelizumab as monotherapy or in combination with chemotherapy in patients with advanced cancers.

e14617 Background: The PD-1 inhibitor tislelizumab (TIS) has demonstrated efficacy and tolerability in patients (pts) with advanced cancers. To evaluate long-term safety of TIS as monotherapy (mono) or in combination (combo) with chemotherapy in pts with advanced gastrointestinal (GI) and lung cancers, data were pooled from 8 pivotal phase III studies conducted between 2017 and 2023. Methods: 2636 adult pts with GI (n=1415) or lung (n=1221) cancers and an ECOG PS of 0-1, who received ≥1 dose of study drug, were included. Endpoints included immune-mediated adverse events (imAEs) by tumor type, treatment (Tx) duration, and race. Early and delayed imAEs, defined as occurring within 1 year (yr) and >1 yr after starting TIS, respectively, were also evaluated. Results: Median (range) Tx duration in the GI and lung cancer studies was 4.9 (0.1-50.4) and 6.2 (0.2-44.9) months, respectively, with 20.9% and 29.6% of pts, respectively, having ≥1 yr exposure. Most pts were Asian (GI mono: 76.4%; GI combo: 74.9%; lung mono: 79.2%; lung combo: 100%). ImAEs occurred in 32.5% of pts in the GI mono and combo studies (Table); most were low grade, with grade ≥3 imAEs reported in 6.2% (mono) and 8.2% (combo) of pts. Incidence of imAEs in the mono and combo lung studies, respectively, was 34.3% and 43.7% (grade ≥3: 6.4% and 9.6%). ImAE incidence was comparable between Asian and White race subgroups, respectively, in the GI mono (33.6% vs 29.5%), GI combo (34.9% vs 23.9%), and lung mono (35.5% vs 32.3%) studies. Most imAEs occurred within 1 yr of starting TIS in the GI (mono: 32.0%; combo: 32.4%) and lung (mono: 34.1%; combo: 42.2%) studies. Delayed imAEs occurred less often than early imAEs; of pts still on Tx or in study follow-up 1 yr after initial Tx, 54/757 (7.1%) in GI studies and 86/804 (10.7%) in lung studies experienced a delayed imAE. Frequently reported imAEs were consistent, regardless of time of onset (early vs delayed). Conclusions: This long-term, retrospective, pooled analysis supports TIS as a tolerable Tx for pts with advanced GI and lung cancers. Delayed imAEs were relatively infrequent and were consistent with the established safety profile of TIS. Clinical trial information: NCT03412773 ; NCT03430843 ; NCT03358875 ; NCT03663205 ; NCT03777657 ; NCT03783442 ; NCT03594747 ; NCT04005716 . [Table: see text]

The efficacy of immune checkpoint inhibitors in patients with cancer with pseudoprogression.

2620 Background: Pseudoprogression (PsP) is quite a common phenomenon in cancer patients undergoing therapy with immune checkpoint inhibitors (ICI). It could be defined as temporary increase of tumor volume or the number of tumor lesions after beginning of ICI treatment (immune unconfirmed progressive disease - iUPD) followed by clinical response. However, many specialists in real clinical practice are hesitant to continue ICI therapy in patients with iUPD because of medical or financial constraints. We aimed to evaluate the efficacy of ICI in patients with clinical evidence of PsP. Methods: We retrospectively analyzed 1001 cases of ICI treatment (male 58,4%, age 28-90 years) in patients with various solid malignancies: melanoma – 316, lung – 280, kidney – 247, GI cancer – 96, cervix of the uteri – 62. The patients were treated in 2 regional referral centers in Moscow and Moscow Region between June 2018 and Dec. 2022. Unconfirmed progressive disease (iUPD) according to iRECIST criteria was diagnosed in 316 patients at the first imaging control after the beginning of ICI treatment (31,6%). Results: Among 316 patients with iUPD the presence of progression (immune confirmed progressive disease – iCPD) was verified in 105 (33,2%): melanoma – 109 (34,5%), lung – 86 (30,7%), kidney – 75 (30,4%), GI cancer – 42 (43,8%), cervix of the uteri – 4 (6,5%). Stable disease was found in 144 (45,6%), partial response in 50 (15,8% - iPR), complete response in 17 patients (5,4% - iCR). Altogether, PsP was diagnosed in 211 of 1001 patients (21,1%). Overall objective response rate in 316 patients with iUPD reached 21,2%, control over disease was achieved in 66,8% of cases. Severe immune-mediated adverse events (3-4 st. according to CTC AE 5.0) were diagnosed in 9 patients (2,8%). Median overall survival in patients with iUPD and ORR was 60,65 mon (95%CI 57,54-63,76), in patients without iUPD and ORR – 147,56 mon (95%CI 137,2-157,93). Conclusions: PsP was diagnosed in 21,1% of patients getting ICI treatment in real clinical practice with median survival in PsP patients with objective response of about 60 months. Only 10,5% of patients had iCPD after their second follow-up. We feel that close adherence to iRECIST criteria to verify true progression is mandatory in patients under ICI treatment to exclude unnecessary cessation of treatment.

The timing of checkpoint inhibition in relation to stem cell transplantation increases the risk of inflammatory adverse events.

e14706 Background: Stem cell transplantation (SCT) and immune checkpoint inhibitors (ICIs) are both used to treat hematological malignancies. There may sometimes be an overlap in the patient’s exposure to both treatments. Theoretically, ICIs potentiate the graft-versus-tumor effect following SCT but may increase the risk of inflammatory adverse events (AEs). Conversely, immunosuppression following SCT may decrease the risk of immune-mediated AEs. We aim to explore the effect of immunotherapy on the risk and severity of inflammatory AEs following SCT. Methods: We performed a single-center, retrospective chart review including all patients with a hematological malignancy who were treated with immunotherapy and received SCT. Patients who did not receive immunosuppressive regimens after their transplant (e.g., autologous transplants) were excluded. Patients were divided into 2 groups based on the timing of ICI: pre-SCT ICI (group 1) and post-SCT ICI (group 2). We gathered clinical data including patient demographics, post-SCT immunosuppressive regimens, and pre- and post-SCT inflammatory AEs. Results: 63 patients were included. Around 82% of patients in group 1 experienced a post-transplant AE compared to 50% in group 2 ( p = 0.014). These AEs occurred earlier in group 1 patients (median 57 days in group 1 vs. 195 in group 2; p = 0.007). Roughly 80% of the inflammatory conditions involved the gastrointestinal system. Severity and complication rates did not differ between groups, but gastrointestinal inflammation in group 1 was more likely to require immunosuppressive medication (75.7% and 37.8% requiring corticosteroids and selective immunosuppressive therapy, respectively, in group 1 patients vs. 33.3% and 0% in group 2 patients; p < 0.05). Conclusions: To our knowledge, our study is one of few exploring the impact of ICI timing in relation to SCT on the risk of post-SCT inflammatory AEs. Administration of immunotherapy prior to SCT may predispose patients to inflammatory AEs after SCT, which may occur earlier and last longer than if ICIs are started after SCT. Future studies are needed to further explore this phenomenon. [Table: see text]

A phase II trial of sitravatinib plus nivolumab after progression on prior immune checkpoint inhibitor (ICI) in patients with metastatic clear cell renal cell carcinoma (ccRCC).

4542 Background: Sitravatinib, an oral multi-kinase inhibitor targeting VEGFR, TAM, and MET, has been shown to resensitize the tumor microenvironment to ICI by reducing immune-suppressive myeloid cells in metastatic ccRCC (Msaouel, Sci Transl Med 2022). ICI is the standard first-line (1L) treatment of metastatic ccRCC, and there is unmet need for improved treatment outcomes after progression on ICI. We hypothesized that sitravatinib plus nivolumab would revert an immunosuppressive tumor microenvironment (TME) to improve objective response rate (ORR) and survival in patients with metastatic ccRCC whose disease progressed on or after ICI. Methods: In this investigator-initiated, phase II, multicenter trial (NCT04904302), patients with progressive metastatic ccRCC after 1-2 lines of treatment were enrolled into three cohorts: Cohort A) progression on 1L nivolumab + ipilimumab, Cohort B) progression on 1L pembrolizumab + axitinib or 2L anti-PD-1 therapy after receiving 1L VEGF-targeted monotherapy, Cohort C) progression on 1L or 2L cabozantinib or lenvatinib +/- everolimus either before, after, or in combination with anti-PD-1 ICI. Starting dose of sitravatinib was 100 mg PO daily and nivolumab was 480 mg IV every 4 weeks. The co-primary endpoints were ORR [complete response (CR) + partial response (PR)] and disease control rate [DCR; CR, PR or stable disease (SD) at 24 weeks]. The study was designed to enroll 88 patients with an interim analysis for futility in each cohort using a BOP2 design, but it was terminated early due to discontinuation of sitravatinib development by the sponsor. Results: 14 patients were enrolled with 2 in cohort A, 6 in cohort B and 6 in cohort C. Most patients had IMDC intermediate risk disease (n=11, 78.6%), 7 patients had prior nephrectomy (50%), and sarcomatoid dedifferentiation was present in the tumors of 2 patients (7.1%). Across all cohorts, the ORR was 15.4% (2/13, 1 patient not evaluable) and DCR at 24 weeks was 35.7% (5/14). The 2 patients who experienced a PR were pre-treated with nivolumab + ipilimumab and pembrolizumab + axitinib. DCR at 24 months was 63% for Cohort A+B and 0% for Cohort C. After a median follow up of 11.9 months (mo), 10 patients had discontinued treatment (71.4%), all due to disease progression, and 6 patients had died (42.9%). Median progression free survival was 5.5 mo [ 95% CI 3.8 – not reached (NR)], and median overall survival was 13.3 mo (95% CI 8.77 – NR). Six patients (42.9%) experienced a grade 3-4 adverse event (AE) and 2 patients (14.3%) experienced an immune-mediated AE. Conclusions: In this small phase 2 trial with limited sample size due to early termination, sitravatinib plus nivolumab demonstrated a manageable safety profile and produced modest clinical benefit. The observed responses occurred in patients who did not receive prior treatment with cabozantinib or lenvatinib. Clinical trial information: NCT04904302 .

KEYNOTE-158: Final analysis of pembrolizumab in patients of Chinese descent with microsatellite instability-high/mismatch repair deficient advanced solid tumors.

e15137 Background: The multicohort non-randomized, phase 2 KEYNOTE-158 (NCT02628067) trial supported the FDA approval of pembrolizumab for unresectable or metastatic microsatellite instability-high (MSI-H)/mismatch repair deficient (dMMR) solid tumors. Incidence of advanced MSI-H/dMMR tumors in patients (pts) of Chinese descent is similar to that in Western populations. In KEYNOTE-158 cohort L, we evaluated the antitumor activity of pembrolizumab in pts of Chinese descent with MSI-H/dMMR solid tumors. We previously reported an ORR of 70% in 20 pts from cohort L. Here we present results of the final analysis for 30 pts with 18 months (mo) of follow up. Methods: Eligible pts of Chinese descent from China aged ≥18 years were enrolled. Pts had to have confirmed unresectable or metastatic MSI-H/dMMR tumors, and ≥1 prior lines of therapy. Pts received 200 mg pembrolizumab Q3W for up to 35 cycles, until progression, unacceptable toxicity, or pt/investigator withdrawal. MSI-H/dMMR status was assessed centrally by PCR and IHC. The primary endpoint was ORR per RECIST 1.1 by central review. Secondary endpoints were DOR, PFS, OS and safety. The database cut-off date was May 5, 2023. Results: A total of 30 pts were enrolled; 7 (23%) were aged ≥65 years, and 20 (67%) were female. At data cut-off, 14 (47%) pts discontinued treatment; 12 (40%) due to progressive disease, 1 (3%) due to adverse events (AE), and 1 (3%) due to physician decision. The median follow-up (range) was 18.0 mo (6.4 – 32.7). The ORR was 66.7% (6 CR; 14 PR [95% CI: 47.2%- 82.7%]). The median DOR was not reached (NR) (range, 1.8+ - 29.5+) with a 12-mo DOR rate of 85.9%. Median PFS was NR (95% CI: 8.1-NR) with an 18-mo PFS rate of 63.0%. The median OS was NR (95% CI: 19.1, NR) with an 18-mo OS rate of 78.8%. Treatment-related AEs were reported in 22 (73%) pts. Grade 3-4 treatment-related AEs occurred in 7 (23%) pts. There were no grade 5 AEs. Immune-mediated AEs occurred in 11 pts (37%); 2 (7%) had grade 3 AEs (myositis or rash in 1 pt each). No grade 4-5 immune-mediated AEs occurred. Conclusions: Pembrolizumab continues to provide clinically meaningful antitumor activity and durable responses with a manageable safety profile in pts of Chinese descent with MSI-H/dMMR tumors. No new safety signals were identified. These results are consistent with those reported in the global population and further support the use of pembrolizumab in pts of Chinese descent with MSI-H/dMMR tumors. Clinical trial information: NCT02628067 .

Phase 1 study of anti–immunoglobulin-like transcript 3 (ILT3) monoclonal antibody (mAb) MK-0482 + pembrolizumab (pembro) in patients with recurrent inoperable glioblastoma (GBM).

2046 Background: For patients with GBM, treatment options are limited once the disease has recurred and become inoperable after standard first-line therapy. ILT3 is an inhibitory receptor expressed on monocytic myeloid cells, including tolerogenic dendritic cells and myeloid-derived suppressor cells (MDSCs). High expression of ILT3 on these immune cells has been associated with immune tolerance and suppression of T-cell function. Data have shown that GBMs have high ILT3 expression and high levels of MDSCs within the tumor microenvironment (TME). MK-0482 is a novel humanized IgG4 mAb targeting ILT3. Inhibition of ILT3 with MK-0482 may help relieve immunosuppression and improve T-cell function within the TME. In the expansion cohort of the first-in-human phase 1 study (MK-0482-001; NCT03918278), MK-0482 was evaluated in combination with pembro in a cohort of patients with recurrent inoperable GBM. The safety and efficacy data from this cohort are presented herein. Methods: Patients aged ≥18 y with their first recurrent inoperable GBM and a Karnofsky performance status (KPS) ≥80 were enrolled. Patients received MK-0482 750 mg Q3W + pembro 200 mg Q3W IV for up to a maximum of 35 cycles. The primary objective was to determine safety and tolerability of MK-0482 + pembro. Secondary objectives were to evaluate ORR, DCR (CR + PR + SD), and DOR by investigator assessment per Response Assessment in Neuro-Oncology (RANO). Exploratory objectives included evaluation of PFS per RANO and OS. Results: Overall, 25 patients were enrolled and received study treatment. At data cutoff (October 3, 2023), median follow-up duration was 9.3 mo (range, 5.6-14.5); treatment was ongoing in 1 patient. Median age was 56 y (range, 33-76). Most patients were male (72%), had a KPS of 80 (68%), and had IDH1 wild-type tumors (88%). All patients had previously received systemic therapy: 24 of 25 (96%) received prior temozolomide and 3 of 25 (12%) received prior glasdegib. Overall, 22 patients (88%) had an adverse event (AE); 10 patients (40%) had treatment-related AEs, most commonly (≥10%) arthralgia (12%), fatigue (12%), and increased ALT (12%). Grade 3 treatment-related AEs occurred in 2 patients (8%; increased ALT [n = 1] and fatigue [n = 1]). No grade 4 or 5 treatment-related AEs occurred. Four patients (16%) experienced immune-mediated AEs (hypothyroidism, n = 2; hepatitis, n = 1; pancreatitis, n = 1); all were grade 1 or 2. Confirmed ORR was 12% (3/25; 95% CI, 2.5-31.2), DCR was 32% (8/25; 14.9-53.5), and median DOR was 11.1 mo (range, 9.9-16.6+). Median PFS was 1.4 mo (95% CI, 1.3-2.9) and median OS was 9.3 mo (6.3-13.7); 6-/12-mo PFS and OS rates were 24%/16% and 72%/36%, respectively. Biomarker data will be included in the presentation. Conclusions: MK-0482 + pembro had a manageable AE profile with modest antitumor activity in patients with recurrent inoperable GBM. Clinical trial information: NCT03918278 .

Safety of pembrolizumab as adjuvant therapy in a pooled analysis of phase 3 clinical trials of melanoma, non–small cell lung cancer, and renal cell carcinoma

BackgroundThe safety profile of adjuvant pembrolizumab was evaluated in a pooled analysis of 4 phase 3 clinical trials. MethodsPatients had completely resected stage IIIA, IIIB, or IIIC melanoma per American Joint Committee on Cancer, 7th edition, criteria (AJCC-7; KEYNOTE-054); stage IIB or IIC melanoma per AJCC-8 (KEYNOTE-716); stage IB, II, or IIIA non–small cell lung cancer per AJCC-7 (PEARLS/KEYNOTE-091); or postnephrectomy/metastasectomy clear cell renal cell carcinoma at increased risk of recurrence (KEYNOTE-564). Patients received adjuvant pembrolizumab 200 mg (2 mg/kg up to 200 mg for pediatric patients) or placebo every 3 weeks for approximately 1 year. Adverse events (AEs) were summarized for patients who received ≥ 1 dose of treatment. ResultsData were pooled from 4125 patients treated with pembrolizumab (n = 2060) or placebo (n = 2065). Median (range) duration of treatment was 11.1 months (0.0–18.9) with pembrolizumab and 11.2 months (0.0–18.1) with placebo. Treatment-related AEs occurred in 78.6 % (1620/2060) of patients in the pembrolizumab group (grade 3–5, 16.3 % [336/2060]) and 58.7 % (1212/2065) in the placebo group (grade 3–5, 3.5 % [72/2065]). Immune-mediated AEs (e.g. adrenal insufficiency, hypophysitis, and thyroiditis) occurred in 36.2 % (746/2060) of patients in the pembrolizumab group (grade 3–5, 8.6 % [177/2060]) and 8.4 % (174/2065) in the placebo group (grade 3–5, 1.1 % [23/2065]). Of patients with ≥ 1 immune-mediated AE or infusion reaction, systemic corticosteroids were required for 35.2 % (268/761) and 20.2 % (39/193) of patients in the pembrolizumab and placebo groups, respectively. ConclusionsAdjuvant pembrolizumab demonstrated a manageable safety profile that was comparable to prior reports in advanced disease.

Abstract PO1-03-10: Differential microbial metabolic pathways associated with resistance to neoadjuvant immunotherapy in locally advanced triple negative breast cancer

Abstract Differential microbial metabolic pathways associated with resistance to neoadjuvant immunotherapy in locally advanced triple negative breast cancer Background: It has previously been shown that microbial metabolic pathways are differentially activated in immunotherapy resistance, hence can serve as potential targets for therapeutic intervention. With the advent of Immune Checkpoint Blockers in the neoadjuvant setting of locally advanced (LA) TNBC, we hypothesized that similar microbial metabolite mediated resistance may be at play. We are presenting the real world data for neoadjuvant treatment in early TNBC along with a subset of tumor metabolite analysis. Method: 35 patients who received neoadjuvant pembrolizumab and chemotherapy for LA TNBC were identified at Moffitt Cancer Center between July 2019 to January 2023. These included 22 Caucasian, 5 African American, 2 Hispanic and 6 patients with undisclosed race. The age range was 33-78 years. The weight and Body Mass Index range was 55.3 kg-127.3 kg and 20.96-45.43 kg/m2 respectively. Nine patients had stage III disease while 24 had stage II breast cancer. The response was assessed in 33 patients; 20 patients (60.6%) achieved pathological complete response (pCR) and 13 (39.4%) had residual disease (RD). 1 patient developed severe immune mediated toxicity with colitis, hepatitis, myasthenia gravis leading to death while 1 patient had disease progression leading to drug discontinuation. Six patients developed immune mediated adverse events. We conducted untargeted metabolomic profiling on 24 patients to identify differentially abundant metabolites associated with pCR (ypT0/is ypN0) vs RD; 16 vs 8 patients respectively. Formalin fixed paraffin embedded (FFPE) slides from tumor tissue vs tumor bed were retrieved and histopathological evaluation of tumor cells was performed. 20 μm sections of FFPE block were used for untargeted metabolomics via liquid chromatography/mass spectrometry. Among the 200 metabolites detected, 63 were differentially abundant between pCR and tumor samples with RD. After correcting for false discovery rate, we observed striking differential activation of two microbial metabolic pathways. Samples with RD had significantly elevated kynurenine (OR-3.64 X1034, P-1.94 X 10-74 and kynurenine/Tryptophan ratio). The tryptophan, kynurenine pathway has been known to be overexpressed in patients resistant to immunotherapy and modulated by the microbiome. Similarly, the purine metabolic pathway, specifically microbiota-derived immunostimulatory metabolites- inosine, hypoxanthine, uric acid were significantly depleted in patients with RD (Inosine OR-0.54, p-0.007, Hypoxanthine OR-0.5, p-0.00039, uric acid OR: 0.41, P-0.003). Previously Inosine has been shown to increase the anti-tumor effects of immune checkpoint blockade by enhancing CD8+ effector T-cell function. Hence depletion of inosine, hypoxanthine and uric acid signals lack of an effector CD8 T cell response. Conclusion: Despite being a small study, it corroborates pCR rates noted in KEYNOTE 522 in the real world setting but shows significant concern for serious immune mediated adverse effects. This highlights the importance of stratifying patients who might be resistant to ICB or develop significant toxicities, thus deriving little to no benefit from standard neoadjuvant treatment. This underscores the need to develop precision-based treatment algorithms. The study represents one of the first investigations of differential abundance of microbial metabolites with immunotherapy resistance in LA TNBC. Our results highlight two microbially mediated mechanisms that could be targeted to improve pCR rates in LA TNBC. We are working to identify microbial metabolic pathways associated with immune mediated toxicity. Citation Format: Humaira Sarfraz, Brian Czerniecki, Zena Jameel, Michael Jaglal, Mostafa Eysha, Turkan Ozkul, Jameel Muzaffar, Aditi Saha, Sara Sarfraz, Fatima Zahra, Min Liu, Khushali Jhaveri, Melissa Sur, Adrianna Bagos-Estevez, Shahla Bari. Differential microbial metabolic pathways associated with resistance to neoadjuvant immunotherapy in locally advanced triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-03-10.