CD19 occupancy with tafasitamab increases therapeutic index of CART19 cell therapy and diminishes severity of CRS

ABSTRACT

In the development of various strategies of anti-CD19 immunotherapy for the treatment of B-cell malignancies, it remains unclear whether CD19 monoclonal antibody therapy impairs subsequent CD19-targeted chimeric antigen receptor T-cell (CART19) therapy. We evaluated the potential interference between the CD19-targeting monoclonal antibody tafasitamab and CART19 treatment in preclinical models. Concomitant treatment with tafasitamab and CART19 showed major CD19 binding competition, which led to CART19 functional impairment. However, when CD19+ cell lines were pretreated with tafasitamab overnight and the unbound antibody was subsequently removed from the culture, CART19 function was not affected. In preclinical in vivo models, tafasitamab pretreatment demonstrated reduced incidence and severity of cytokine release syndrome and exhibited superior antitumor effects and overall survival compared with CART19 alone. This was associated with transient CD19 occupancy with tafasitamab, which in turn resulted in the inhibition of CART19 overactivation, leading to diminished CAR T apoptosis and pyroptosis of tumor cells.

Tucatinib and Trastuzumab for Previously Treated Human Epidermal Growth Factor Receptor 2-Positive Metastatic Biliary Tract Cancer (SGNTUC-019): A Phase II Basket Study

PURPOSE

To evaluate the efficacy and safety of tucatinib and trastuzumab in patients with previously treated human epidermal growth factor receptor 2-positive (HER2+) metastatic biliary tract cancer (mBTC).

METHODS

SGNTUC-019 (ClinicalTrials.gov identifier: NCT04579380) is an open-label phase II basket study evaluating the efficacy and safety of tucatinib and trastuzumab in patients with HER2-altered solid tumors. In the biliary tract cancer cohort, patients had previously treated HER2 overexpressing or amplified (HER2+) tumors (identified with local testing) with no prior HER2-directed therapy. The primary end point was confirmed objective response rate (cORR) per investigator assessment. Patients were treated on a 21-day cycle with tucatinib (300 mg orally twice daily) and trastuzumab (8 mg/kg intravenously followed by 6 mg/kg every 3 weeks).

RESULTS

Thirty patients were enrolled. As of data cutoff (January 30, 2023), the median duration of follow-up was 10.8 months. The cORR was 46.7% (90% CI, 30.8 to 63.0), with a disease control rate of 76.7% (90% CI, 60.6 to 88.5). The median duration of response and progression-free survival were 6.0 months (90% CI, 5.5 to 6.9) and 5.5 months (90% CI, 3.9 to 8.1), respectively. At data cutoff, 15 patients (50.0%) had died, and the estimated 12-month overall survival rate was 53.6% (90% CI, 36.8 to 67.8). The two most common treatment-emergent adverse events (TEAEs) were pyrexia (43.3%) and diarrhea (40.0%). Grade ≥3 TEAEs were reported in 18 patients (60.0%), with the most common being cholangitis, decreased appetite, and nausea (all 10.0%), which were generally not treatment related. TEAEs led to treatment regimen discontinuation in one patient, and there were no deaths due to TEAEs.

CONCLUSION

Tucatinib combined with trastuzumab had clinically significant antitumor activity and was well tolerated in patients with previously treated HER2+ mBTC.

AXL Inhibition Improves the Antitumor Activity of Chimeric Antigen Receptor T Cells

The receptor tyrosine kinase AXL is a member of the TYRO3, AXL, and proto-oncogene tyrosine-protein kinase MER family and plays pleiotropic roles in cancer progression. AXL is expressed in immunosuppressive cells, which contributes to decreased efficacy of immunotherapy. Therefore, we hypothesized that AXL inhibition could serve as a strategy to overcome resistance to chimeric antigen receptor T (CAR T)-cell therapy. To test this, we determined the impact of AXL inhibition on CD19-targeted CAR T (CART19)-cell functions. Our results demonstrate that T cells and CAR T cells express high levels of AXL. Specifically, higher levels of AXL on activated Th2 CAR T cells and M2-polarized macrophages were observed. AXL inhibition with small molecules or via genetic disruption in T cells demonstrated selective inhibition of Th2 CAR T cells, reduction of Th2 cytokines, reversal of CAR T-cell inhibition, and promotion of CAR T-cell effector functions. AXL inhibition is a novel strategy to enhance CAR T-cell functions through two independent, but complementary, mechanisms: targeting Th2 cells and reversing myeloid-induced CAR T-cell inhibition through selective targeting of M2-polarized macrophages.

Phase II study of FGFR1-3 inhibitor tinengotinib as monotherapy in patients with advanced or metastatic cholangiocarcinoma: Interim analysis

539

Background: Tinengotinib is a spectrum-selective multi-kinase inhibitor with a unique FGFR-binding mechanism. It potently inhibits FGFR2 fusion/rearrangement and acquired resistant mutations in pre-clinical models and early clinical studies in cholangiocarcinoma (CCA). Here we present the preliminary efficacy and safety of tinengotinib (TT-00420) in a phase II trial TT420C1206 (NCT04919642). Methods: Eligible patients (pts) with advanced/metastatic CCA exhausting standard treatment options received tinengotinib 10 mg QD. Pts were enrolled into four cohorts using historical FGFR alteration status: FGFR2 fusion(s) with primary progression on previous FGFR inhibitor (FGFRi) (A1) or progression after prior response to FGFRi (acquired resistance) (A2); non-fusion FGFR alteration(s) (B); or FGFR wild-type (FGFRwt, C). Primary endpoint was objective response rate (ORR) per RECIST version 1.1. Safety, PK parameters, and biomarker profile were evaluated and reviewed jointly with the efficacy outcomes. Adverse events (AEs) were graded per CTCAE version 5.0. Results: As of Sep 13, 2022, 25 pts with CCA were enrolled and dosed; 7 in A1, 6 in A2, 2 in B and 10 in C. Median age 61 [range 24-82] years old, 64% female, 93.3% had ≥ 3 prior treatment lines. 13 patients with ECOG 0 and 12 patients with ECOG 1 at baseline. Among 15 patients with historical FGFR alterations (13 fusions/rearrangement and 2 mutations), 93.3% had ≥ 1 prior FGFRi, and 3 pts (20.0%) had 2 prior FGFRi treatments. Eighteen pts were evaluable for tumor assessment at data cutoff date, including 4 in A1, 6 in A2, 1 in B and 7 in C. The median follow up was 15 weeks. In A2, 2 out of 6 pts (33%) achieved PR with tumor reductions of 34% and 54%. Overall DCR (CR or PR+SD) was 90% (9/10) in FGFR2 fusion/rearrangement pts; 100% in FGFR primary mutation pt (1/1); and 71% (5/7) in FGFRwt pts. One PR and 5 SDs lasted for more than 16 weeks. Among 25 treated pts, drug-related AEs occurred in 20 (80%) pts, including 7 (28%) with Grade (G) 1-2 AEs, 12 (48%) with G3 AEs, and 1 (4%) with G4 AE. Most frequently occurred G3/4 AEs were hypertension in 6 (24%) pts, including 5 (20%) with G3 and 1 (4%) with G4, G3 fatigue in 2 (8%) and G3 neutrophil count decreased in 2 (8%) pts. No drug-related G5 was observed. The efficacy and safety results observed were consistent with the previous reported data ( NCT03654547 ) in CCA pts. The preliminary biomarker analysis suggests loss of resistant FGFR mutation on liquid biopsy post tinengotinib therapy. Further biomarker analysis will be updated at the presentation. Conclusions: Tinengotinib may result in promising clinical benefit for CCA pts in the setting of FGFRi-resistance. Tinengotinib-related toxicities were manageable. An ongoing phase II study will further provide safety, efficacy and biomarker evaluations for both FGFR resistant and FGFRwt CCA. Clinical trial information: NCT04919642 .

Association of PD-L1 Expression and Other Variables With Benefit From Immune Checkpoint Inhibition in Advanced Gastroesophageal Cancer: Systematic Review and Meta-analysis of 17 Phase 3 Randomized Clinical Trials

Importance

Approval by the US Food and Drug Administration of immune checkpoint inhibition (ICI) for advanced gastroesophageal cancer (aGEC) irrespective of PD-L1 status has generated controversy. Exploratory analyses from individual trials indicate a lack of meaningful benefit from ICI in patients with absent or low PD-L1 expression; however, analysis of a single variable while ignoring others may not consider the instability inherent in exploratory analyses.

Objective

To systematically examine the predictive value of tissue-based PD-L1 status compared with that of other variables for ICI benefit in aGEC to assess its stability.

Data Sources

MEDLINE, Embase, Scopus, Web of Science, Cochrane Central Register (2000-2022).

Study Selection, Data Extraction, and Synthesis

Randomized clinical trials (RCTs) were included of adults with aGEC (adenocarcinoma [AC] or squamous cell carcinoma [SCC]) randomized to anti-PD-1 or PD-L1-containing treatment vs standard of care (SOC). Study screening, data abstraction, and bias assessment were completed independently by 2 reviewers. Of 5752 records screened, 26 were assessed for eligibility; 17 trials were included in the analysis.

Main Outcomes and Measures

The prespecified primary end point was overall survival. The mean hazard ratio (HR) for ICI vs SOC was calculated (random-effects model). Predictive values were quantified by calculating the ratio of mean HRs between 2 levels of each variable.

Results

In all, 17 RCTs (9 first line, 8 after first line) at low risk of bias and 14 predictive variables were included, totaling 11 166 participants (5067 with SCC, 6099 with ACC; 77.6% were male and 22.4% were female; 59.5% of patients were younger than 65 years, 40.5% were 65 years or older). Among patients with SCCs, PD-L1 tumor proportion score (TPS) was the strongest predictor of ICI benefit (HR, 0.60 [95% CI, 0.53-0.68] for high TPS; and HR, 0.84 [95% CI, 0.75-0.95] for low TPS), yielding a predictive value of 41.0% favoring high TPS (vs ≤16.0% for other variables). Among patients with AC, PD-L1 combined positive score (CPS) was the strongest predictor (after microsatellite instability high status) of ICI benefit (HR, 0.73 [95% CI, 0.66-0.81] for high CPS; and HR, 0.95 [95% CI, 0.84-1.07] for low CPS), yielding a predictive value of 29.4% favoring CPS-high (vs ≤12.9% for other variables). Head-to-head analyses of trials containing both levels of a variable and/or having similar design generally yielded consistent results.

Conclusions and Relevance

Tissue-based PD-L1 expression, more than any variable other than microsatellite instability-high, identified varying degrees of benefit from ICI-containing therapy vs SOC among patients with aGEC in 17 RCTs.

Targeting cancer-associated fibroblasts in the bone marrow prevents resistance to CART-cell therapy in multiple myeloma

Pivotal clinical trials of B-cell maturation antigen-targeted chimeric antigen receptor T (CART)-cell therapy in patients with relapsed/refractory multiple myeloma (MM) resulted in remarkable initial responses, which led to a recent US Food and Drug Administration approval. Despite the success of this therapy, durable remissions continue to be low, and the predominant mechanism of resistance is loss of CART cells and inhibition by the tumor microenvironment (TME). MM is characterized by an immunosuppressive TME with an abundance of cancer-associated fibroblasts (CAFs). Using MM models, we studied the impact of CAFs on CART-cell efficacy and developed strategies to overcome CART-cell inhibition. We showed that CAFs inhibit CART-cell antitumor activity and promote MM progression. CAFs express molecules such as fibroblast activation protein and signaling lymphocyte activation molecule family-7, which are attractive immunotherapy targets. To overcome CAF-induced CART-cell inhibition, CART cells were generated targeting both MM cells and CAFs. This dual-targeting CART-cell strategy significantly improved the effector functions of CART cells. We show for the first time that dual targeting of both malignant plasma cells and the CAFs within the TME is a novel strategy to overcome resistance to CART-cell therapy in MM.

Rapidly Evolving Treatment Landscape for Metastatic Esophagogastric Carcinoma: Review of Recent Data

Esophagogastric cancer (EGC) is a heterogeneous group of malignancies that collectively represent the 2nd leading cause of cancer deaths worldwide. While surgery in combination with chemotherapy and/or radiation therapy represents the primary curative treatment for early stage disease, survival outcomes for the majority of patients with later-stage disease remain poor. Cytotoxic chemotherapy with platinum doublets such as 5-FU/leucovorin/oxaliplatin is the mainstay of treatment with incremental benefits provided by targeted therapy (trastuzumab, trastuzumab deruxtecan, ramucirumab) and immunotherapy (pembrolizumab, nivolumab). In this article, we provide an updated review and perspectives on the management of advanced EGC. We examine the distinct epidemiological, etiological and molecular features of each disease entity comprising EGC. After reviewing the critical studies that established conventional systemic cytotoxic and targeted therapeutics, we elaborate on recent promising and complex data with immune checkpoint inhibition focusing on implications of tumor histology and PD-L1 expression in the tumor microenvironment. We also highlight novel diagnostic and therapeutic strategies to build on these recent advances.

Development of a Clinically Relevant Reporter for Chimeric Antigen Receptor T-cell Expansion, Trafficking, and Toxicity

Although chimeric antigen receptor T (CART)-cell therapy has been successful in treating certain hematologic malignancies, wider adoption of CART-cell therapy is limited because of minimal activity in solid tumors and development of life-threatening toxicities, including cytokine release syndrome (CRS). There is a lack of a robust, clinically relevant imaging platform to monitor in vivo expansion and trafficking to tumor sites. To address this, we utilized the sodium iodide symporter (NIS) as a platform to image and track CART cells. We engineered CD19-directed and B-cell maturation antigen (BCMA)-directed CART cells to express NIS (NIS⁺CART19 and NIS⁺BCMA-CART, respectively) and tested the sensitivity of ¹⁸F-TFB-PET to detect trafficking and expansion in systemic and localized tumor models and in a CART-cell toxicity model. NIS⁺CART19 and NIS⁺BCMA-CART cells were generated through dual transduction with two vectors and demonstrated exclusive ¹²⁵I uptake in vitro. ¹⁸F-TFB-PET detected NIS⁺CART cells in vivo to a sensitivity level of 40,000 cells. ¹⁸F-TFB-PET confirmed NIS⁺BCMA-CART-cell trafficking to the tumor sites in localized and systemic tumor models. In a xenograft model for CART-cell toxicity, ¹⁸F-TFB-PET revealed significant systemic uptake, correlating with CART-cell in vivo expansion, cytokine production, and development of CRS-associated clinical symptoms. NIS provides a sensitive, clinically applicable platform for CART-cell imaging with PET scan. ¹⁸F-TFB-PET detected CART-cell trafficking to tumor sites and in vivo expansion, correlating with the development of clinical and laboratory markers of CRS. These studies demonstrate a noninvasive, clinically relevant method to assess CART-cell functions in vivo.

Leukemic extracellular vesicles induce chimeric antigen receptor T cell dysfunction in chronic lymphocytic leukemia

Chimeric antigen receptor (CAR) T cell therapy has yielded unprecedented outcomes in some patients with hematological malignancies; however, inhibition by the tumor microenvironment has prevented the broader success of CART cell therapy. We used chronic lymphocytic leukemia (CLL) as a model to investigate the interactions between the tumor microenvironment and CART cells. CLL is characterized by an immunosuppressive microenvironment, an abundance of systemic extracellular vesicles (EVs), and a relatively lower durable response rate to CART cell therapy. In this study, we characterized plasma EVs from untreated CLL patients and identified their leukemic cell origin. CLL-derived EVs were able to induce a state of CART cell dysfunction characterized by phenotypical, functional, and transcriptional changes of exhaustion. We demonstrate that, specifically, PD-L1+ CLL-derived EVs induce CART cell exhaustion. In conclusion, we identify an important mechanism of CART cell exhaustion induced by EVs from CLL patients.

Enhanced efficacy of anti-VEGFR2/taxane therapy after progression on immune checkpoint inhibition (ICI) in patients (pts) with metastatic gastroesophageal adenocarcinoma (mGEA)

4541

Background: Anti-VEGFR2 therapy (ramucirumab/paclitaxel [RAM/TAX]) and ICI are approved as 2nd- and 3rd-line therapy (Tx), respectively, for pts with mGEA. We unexpectedly saw durable responses in 2 pts on RAM/TAX after progression on an ICI trial (KN-059; PMID 29674442). We performed a pilot to examine the clinical activity of ICI followed by RAM/TAX. Then we retrospectively compared the outcomes of pts who received this serial Tx to pts who received RAM/TAX without prior ICI. Methods: All pts with mGEA at Mayo Clinic who received RAM/TAX (2014-19) were included (N = 87). Outcomes were best objective response rate (ORR: complete [CR] or partial response) per RECIST1.1, progression-free survival (PFS), duration of response (DOR), and overall survival (OS). Chi square and multivariate (MV) logistic and Cox regression were used. Results: 15 consecutive pts with measurable mGEA received ICI immediately followed by RAM/TAX after irRECIST progression. Most pts (95%) did not respond to ICI. Yet on RAM/TAX, 100% (15/15) had tumor reduction (range -8% to -100%) with an ORR of 73% (11/15), including 3 CRs. In these pts (who received ICI followed by RAMTAX), PFS on RAMTAX was longer than on last chemotherapy before ICI (12.3 vs 3.0 m, P < .001). Outcomes on RAM/TAX in these pts were significantly better than in pts who received RAM/TAX alone (see Table). Associations were strengthened after adjusting for total lines of Tx, line of Tx of RAM/TAX, age, and ECOG PS. Exploratory analysis of paired tumor biopsies collected pre-ICI and on RAM/TAX in a small subset revealed that the frequency of intratumoral immunosuppressive FOXP3+ Tregs decreased on RAM/TAX, whereas the frequency of antitumor CD8+ T cells was preserved. Conclusions: RAM/TAX immediately preceded by ICI was associated with significantly higher OS, ORR, and DOR than RAM/TAX alone, suggesting ICI may enhance efficacy of subsequent anti-VEGFR/taxane therapy. This novel sequence of therapy will be tested prospectively in a new randomized phase 2 trial (NCT04069273). [Table: see text]

Enhanced efficacy of anti-VEGFR2/taxane therapy after progression on immune checkpoint inhibition (ICI) in patients (pts) with metastatic gastroesophageal adenocarcinoma (mGEA)

362

Background: Most pts with mGEA do not respond to ICI or ramucirumab/paclitaxel (RAM/TAX). Emerging data suggest that ICI may potentiate subsequent therapy (Tx). In KN059 we unexpectedly observed durable responses in 2 pts on RAM/TAX after ICI (PMID 29674442). We examined if ICI impacts efficacy of subsequent RAM/TAX in a larger cohort and explored alterations in the tumor microenvironment. Methods: All pts with mGEA at Mayo Clinic (MN, AZ, FL) who received RAM/TAX (2014-19) were included. We compared best objective response rate (ORR: complete [CR] or partial response [PR]) per RECIST1.1 and overall survival (OS) in pts who received RAM/TAX with (Group A) vs without (Group B) immediately preceding PD-1 blockade. Chi square and multivariate logistic and Cox regression were used. We adjusted for total lines of Tx received and the line of Tx in which RAM/TAX was given, to control for potential differences in the biology of heavily treated pts or those receiving RAM/TAX as 2nd vs 3rd line Tx. We also adjusted for age and ECOG PS. Results: In total 87 pts met inclusion criteria. In the 19 pts (Group A) who received RAM/TAX (usually as 3rd line Tx) after progression on ICI, there was a 77% relative risk reduction of death after initiation of RAM/TAX compared to the 68 pts (Group B) who received RAM/TAX (usually as 2nd line) without preceding ICI (median OS 15.0 vs 7.6 mo; HR 0.23; P < .001). The ORR was also significantly higher (58% vs 18%; P < .001) including the CR rate (16% vs 1%; P = .006). Two CRs in Group A are ongoing (10 - 34 mo). Of note, 95% of Group A pts did not respond to ICI, and all had irRECIST progression on ICI. Immunofluorescent analysis from a responder showed 65-fold reduction (post vs pre-Tx) in intratumoral density of immunosuppressive FOXP3+ Tregs, with preserved density of antitumor CD8+ T cells. Conclusions: Higher than expected efficacy was observed on RAM/TAX when immediately preceded by ICI, suggesting ICI may enhance efficacy of subsequent anti-VEGFR/taxane therapy. This serial immunotherapy combination may be a novel option for pts with primary resistance to ICI and will be tested prospectively in a new randomized phase 2 trial (NCT04069273).

Evaluating unconscious bias: Speaker introductions at an international oncology conference

10503

Background: Gender bias can be reinforced through the use of gender-subordinating language and differences in the forms of address. We examined how professional titles were used during speakers’ introductions at the American Society of Clinical Oncology (ASCO) Annual Meeting. Methods: A retrospective observational study of video-archived speaker introductions at the 2017 and 2018 ASCO annual meetings was conducted. Data were extracted by mixed-gender coders. Professional address was defined as professional title followed by full name or last name. Multivariable logistic regressions were used to identify factors associated with the form of address. Results: 2511 videos were reviewed and 812 met inclusion criteria. Regarding speakers’ characteristics, 530 (65%) were non-Hispanic white (NHW), 743 (92%) held a MD or MD-PhD degree, and 484 (60%) were an associate or full professor. Female speakers were less likely to receive a professional address compared to male speakers (61% vs. 81%, p < 0.001). Female speakers were more likely to be introduced by first name only (17% vs. 3%, p < 0.001). Males were less likely to use a professional address when introducing female speakers compared to male speakers (53% vs. 80%, p < 0.01). No gender differences in professional address were observed for female introducers (p = 0.13). Male introducers were more likely to address female speakers by first name only compared to female introducers (24% vs. 7%, p < 0.01). In a multivariable regression including gender, race, degree, and academic rank, male speakers were more likely to receive a professional address compared to female speakers (OR: 2.67, 95%CI: 1.81-3.94, p < 0.01). Black speakers of both genders were less likely to receive a professional address compared to NHW (OR: 0.10, 95%CI: 0.01-0.53, p < 0.01). Female gender was a predictor for a non-professional form of address (first name only) (OR: 9.50, 95%CI: 4.38-20.62, p < 0.01). Conclusions: When introduced by men, female speakers were less likely to receive a professional address and more likely to be introduced by first name only compared to male speakers. Selective use of forms of address may strengthen gender bias; more research is needed to explore the causes of this disparity and its influence.

Molecular profiling-guided therapy in gastroesophageal carcinoma: A single-institution experience

e15582

Background: Gastroesophageal carcinoma (GEC) including carcinoma of stomach (GC), gastroesophageal junction (GEJ), and esophagus (EC) is the 2nd leading cause of cancer death worldwide. Chemotherapy and HER2-targeted therapy (trastuzumab) have shown limited efficacy. We aim to assess the impact of molecular profile (MP)-guided therapy (MPgt) by correlating expression of select biomarkers in GEC patients (pts) with survival. Methods: 27 GEC (11 GC, 9 GEJ, 7 EC) submitted to Caris Life Sciences for molecular profiling between 2011 and 2016 were analyzed and correlated with pt survival. The impact of MPgt was assessed by calculating the ratio of progression-free survival (PFS) on MPgt to PFS on the preceding empiric therapy. MPgt was deemed beneficial if PFS ratio ≥1.3. Results: In-situ hybridization indicated amplification of HER2 (15.4%) and c-MET (7.4%). Immunohistochemistry revealed increased expression of TOPO1 (57.7%), TOP2A (38.5%), HER2 (15.4%) and c-MET (6.9%), as well as decreased expression of TS (69.2%), ERCC1 (42.3%), and PGP (15.4%). These data suggest sensitivity to topoisomerase inhibitors, anthracyclines, trastuzumab, MET-targeted therapy, fluoropyrimidine, platinums, and taxanes, respectively. Expression of these markers was heterogeneous among pts, and a trend toward improved PFS was noted in pts with low/absent ERCC1 expression on platinum-based therapy ( P= 0.06). Of the 13 pts who had sufficient data to assess the benefit of MPgt, 5 (38%) achieved a PFS ratio ≥1.3. One pt with metastatic HER2-amplified EC who had initially demonstrated clinical benefit from trastuzumab-containing chemotherapy, developed a new HER2 and c-MET co-amplified lung metastasis. Conclusions: While MPgt was beneficial in 38% of pts, tumor-associated plasticity, clonal evolution, and adaptive resistance may have limited efficacy. The emergence of HER2 and c-MET co-amplified clones is a potential resistance mechanism in HER2-amplified GEC, and highlights combined inhibition of receptor tyrosine kinases as a therapeutic strategy. Further studies with expanded data sets will be needed to test the hypothesis that actionable targets can be used independently to predict treatment response in GEC pts.