Validation of a multiomic model of plasma extracellular vesicle PD-L1 and radiomics for prediction of response to immunotherapy in NSCLC

BACKGROUND

Immune-checkpoint inhibitors (ICIs) have showed unprecedent efficacy in the treatment of patients with advanced non-small cell lung cancer (NSCLC). However, not all patients manifest clinical benefit due to the lack of reliable predictive biomarkers. We showed preliminary data on the predictive role of the combination of radiomics and plasma extracellular vesicle (EV) PD-L1 to predict durable response to ICIs.

MAIN BODY

Here, we validated this model in a prospective cohort of patients receiving ICIs plus chemotherapy and compared it with patients undergoing chemotherapy alone. This multiparametric model showed high sensitivity and specificity at identifying non-responders to ICIs and outperformed tissue PD-L1, being directly correlated with tumor change.

SHORT CONCLUSION

These findings indicate that the combination of radiomics and EV PD-L1 dynamics is a minimally invasive and promising biomarker for the stratification of patients to receive ICIs.

Phase I Study of mTORC1/2 Inhibitor Sapanisertib (CB-228/TAK-228) in Combination with Metformin in Patients with mTOR/AKT/PI3K Pathway Alterations and Advanced Solid Malignancies

BACKGROUND

Sapanisertib (CB-228/TAK-228) is a potent, selective ATP-competitive, dual inhibitor of mTORC1/2. Metformin is thought to inhibit the mTOR pathway through upstream activation of 5'-AMP-activated protein kinase (AMPK) suggesting combination therapy may enhance antitumor activity of sapanisertib. We report preliminary safety, tolerability, and efficacy from the dose-escalation study of sapanisertib in combination with metformin in patients with advanced solid tumors.

METHODS

Patients with advanced metastatic solid tumors resistant or refractory to standard treatment, with and without mTOR/AKT/PI3K pathway alterations, received sapanisertib 3 or 4 mg daily together with metformin once to three times daily (500-1,500 mg). All patients underwent 14-day titration period for metformin in cycle 1. Tumor measurements were performed following cycle 2 and subsequently every 8 weeks.

RESULTS

A total of 30 patients were enrolled across four cohorts (3 mg/500 mg; 3 mg/1,000 mg, 4 mg/1,000 mg; 4 mg/1,500 mg). 19 were female (63%), median age was 57 (range: 30-77), all were Eastern Cooperative Oncology Group performance status 1. Tumor types included sarcoma (6), breast (4), ovarian (4), head and neck (3), colorectal (2), lung (2), renal cell (2), endometrial (2), gastroesophageal junction (1), prostate (1), stomach (1), urachus (1), and cervical cancer (1). Median number of prior lines of therapy was 4. Most common genomic alterations included PIK3CA (27%), PTEN (17%), AKT1/2 (10%), mTOR (10%). Of 30 patients evaluable for response, 4 patients achieved partial response (PR); 15 patients achieved stable disease (SD) as best response. Disease control rate (PR+SD) was 63%. Of the responders in PR, 3 of 4 patients had documented PTEN mutations (3/5 patients enrolled with PTEN mutations had PR); 2 of 4 of patients in PR had comutations (patient with leiomyosarcoma had both PTEN and TSC; patient with breast cancer had both PTEN and STK11); 1 of 4 patients in PR had AKT and mTOR mutation; tumor types included leiomyosarcoma (n = 2), breast (n = 1), and endometrial cancer (n = 1). Most common treatment-emergent adverse events included nausea, anorexia, diarrhea, and rash. Grade (G) 3-5 treatment-related adverse events included hyperglycemia (4/30; 13%), fatigue (2/30; 7%), hypertriglyceridemia (1/30; 3%), rash (2/20; 7%), diarrhea (2/30; 7%), creatinine increase (1/30; 3%), acidosis (1/30; 3%). No dose-limiting toxicities (DLT) were reported in the 3 mg/500 mg cohort. One of 6 patient had DLT in the 3 mg/1,000 mg cohort (G3 diarrhea) and 2 of 11 patients had DLTs in the 4 mg/1,500 mg cohort (G3 fatigue, G3 rash). 4 mg/1,000 mg was defined as the MTD.

CONCLUSIONS

The safety profile of mTORC1/2 inhibitor sapanisertib in combination with metformin was generally tolerable, with antitumor activity observed in patients with advanced malignancies harboring PTEN mutations and AKT/mTOR pathway alterations.

SIGNIFICANCE

Sapanisertib (CB-228/TAK-228) is a potent, selective ATP-competitive, next-generation dual inhibitor of mTORC1/2. Metformin is thought to inhibit the mTOR pathway through upstream activation of AMPK suggesting combination therapy may enhance antitumor activity of sapanisertib. This dose-escalation study of sapanisertib and metformin in advanced solid tumors and mTOR/AKT/PI3K pathway alterations, demonstrates safety, tolerability, and early clinical activity in advanced malignancies harboring PTEN mutations and AKT/mTOR pathway alterations.Clinical trial information: NCT03017833.

Phase 1/2 trial of avelumab combined with utomilumab (4-1BB agonist), PF-04518600 (OX40 agonist), or radiotherapy in patients with advanced gynecologic malignancies

BACKGROUND

Immune checkpoint blockade has shown mixed results in advanced/recurrent gynecologic malignancies. Efficacy may be improved through costimulation with OX40 and 4-1BB agonists. The authors sought to evaluate the safety and efficacy of avelumab combined with utomilumab (a 4-1BB agonist), PF-04518600 (an OX40 agonist), and radiotherapy in patients with recurrent gynecologic malignancies.

METHODS

The primary end point in this six-arm, phase 1/2 trial was safety of the combination regimens. Secondary end points included the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors and immune-related Response Evaluation Criteria in Solid Tumors, the disease control rate (DCR), the duration of response, progression-free survival, and overall survival.

RESULTS

Forty patients were included (35% with cervical cancer, 30% with endometrial cancer, and 35% with ovarian cancer). Most patients (n = 33; 83%) were enrolled in arms A-C (no radiation). Among 35 patients who were evaluable for efficacy, the ORR was 2.9%, and the DCR was 37.1%, with a median duration of stable disease of 5.4 months (interquartile range, 4.1-7.3 months). Patients with cervical cancer in arm A (avelumab and utomilumab; n = 9 evaluable patients) achieved an ORR of 11% and a DCR of 78%. The median progression-free survival was 2.1 months (95% CI, 1.8-3.5 months), and overall survival was 9.4 months (95% CI, 5.6-11.9 months). No dose-limiting toxicities or grade 3-5 immune-related adverse events were observed.

CONCLUSIONS

The findings from this trial highlight that, in heavily pretreated patients with gynecologic cancer, even multidrug regimens targeting multiple immunologic pathways, although safe, did not produce significant responses. A DCR of 78% in patients with cervical cancer who received avelumab and utomilumab indicates that further research on this combination in select patients may be warranted.

Phase I study of sapanisertib (CB-228/TAK-228/MLN0128) in combination with ziv-aflibercept in patients with advanced solid tumors

BACKGROUND

Sapanisertib is a potent ATP-competitive, dual inhibitor of mTORC1/2. Ziv-aflibercept is a recombinant fusion protein comprising human VEGF receptor extracellular domains fused to human immunoglobulin G1. HIF-1α inhibition in combination with anti-angiogenic therapy is a promising anti-tumor strategy. This Phase 1 dose-escalation/expansion study assessed safety/ tolerability of sapanisertib in combination with ziv-aflibercept in advanced solid tumors.

METHODS

Fifty-five patients with heavily pre-treated advanced metastatic solid tumors resistant or refractory to standard treatment received treatment on a range of dose levels.

RESULTS

Fifty-five patients were enrolled and treated across a range of dose levels. Forty were female (73%), median age was 62 (range: 21-79), and ECOG PS was 0 (9, 16%) or 1 (46, 84%). Most common tumor types included ovarian (8), colorectal (8), sarcoma (8), breast (3), cervical (4), and endometrial (4). Median number of prior lines of therapy was 4 (range 2-11). Sapanisertib 4 mg orally 3 days on and 4 days off plus 3 mg/kg ziv-aflibercept IV every 2 weeks on a 28-day cycle was defined as the maximum tolerated dose. Most frequent treatment-related grade ≥2 adverse events included hypertension, fatigue, anorexia, hypertriglyceridemia, diarrhea, nausea, mucositis, and serum lipase increase. There were no grade 5 events. In patients with evaluable disease (n = 50), 37 patients (74%) achieved stable disease (SD) as best response, two patients (4%) achieved a confirmed partial response (PR); disease control rate (DCR) (CR + SD + PR) was 78%.

CONCLUSION

The combination of sapanisertib and ziv-aflibercept was generally tolerable and demonstrated anti-tumor activity in heavily pre-treated patients with advanced malignancies.

Utility of Established Prognostic Scoring Systems for Patients with Advanced Pancreatic Adenocarcinoma Enrolled in Immunotherapy-Based Early-Phase Clinical Trials

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy for which multiagent chemotherapy is the mainstay of treatment resulting in limited survival and symptomatic benefit. Treatment with immune checkpoint inhibitors (ICI) has proven effective in a growing number of solid tumors but has yet to show clinical benefit in patients with PDAC. Given the growing number of ICI-based clinical trials in development for patients with PDAC and lack of clinical benefit thus far with ICI-based therapies in these patients, we sought to (1) determine the outcomes of patients with PDAC treated with ICI-based therapies as part of an early phase clinical trial, (2) validate the utility of established prognostic scoring systems, and (3) identify novel prognostic factors in an attempt to better identify patients that would benefit from enrollment onto an ICI-based early phase clinical trial.

METHODS

We conducted a single-center retrospective analysis of patients with advanced PDAC who were treated with ICI-based therapy as part of an early-phase clinical trial.

RESULTS

Patients were only able to stay on study for a limited time due to disease progression and/or a change in performance status and had a poor overall survival. Established prognostic scoring systems were not effective in predicting outcomes in this patient population, but factors such as pre-treatment albumin neutrophil to lymphocyte ratio (NLC) may be helpful in patient selection.

CONCLUSIONS

This study underscores the need for larger studies to help identify patient and tumor intrinsic factors that predict response to ICI-based therapies in patients with PDAC.

Incidence and Risk Factors for Pneumonitis Associated With Checkpoint Inhibitors in Advanced Non-Small Cell Lung Cancer: A Single Center Experience

INTRODUCTION

Immune checkpoint inhibitor (ICI) pneumonitis causes substantial morbidity and mortality. Estimates of real-world incidence and reported risk factors vary substantially.

METHODS

We conducted a retrospective review of 419 patients with advanced non-small cell lung cancer (NSCLC) who were treated with anti-PD-(L)1 with or without anti-CTLA-4 therapy. Clinical, imaging, and microbiological data were evaluated by multidisciplinary adjudication teams. The primary outcome of interest was grade ≥2 (CTCAEv5) pneumonitis. Clinicopathologic variables, tobacco use, cancer therapies, and preexisting lung disease were assessed for univariate effects using Cox proportional hazards models. We created multivariate Cox proportional hazards models to assess risk factors for pneumonitis and mortality. Pneumonitis, pneumonia, and progression were modeled as time-dependent variables in mortality models.

RESULTS

We evaluated 419 patients between 2013 and 2021. The cumulative incidence of pneumonitis was 9.5% (40/419). In a multivariate model, pneumonitis increased the risk for mortality (HR 1.6, 95% CI, 1.0-2.5), after adjustment for disease progression (HR 1.6, 95% CI, 1.4-1.8) and baseline shortness of breath (HR 1.5, 95% CI, 1.2-2.0). Incomplete resolution was more common with more severe pneumonitis. Interstitial lung disease was associated with higher risk for pneumonitis (HR 5.4, 95% CI, 1.1-26.6), particularly in never smokers (HR 26.9, 95% CI, 2.8-259.0).

CONCLUSION

Pneumonitis occurred at a high rate and significantly increased mortality. Interstitial lung disease, particularly in never smokers, increased the risk for pneumonitis.

Pneumonitis After Concurrent Chemoradiation and Immune Checkpoint Inhibition in Patients with Locally Advanced Non-small Cell Lung Cancer

AIMS

Pneumonitis is a common and potentially deadly complication of combined chemoradiation and immune checkpoint inhibition (CRT-ICI) in patients with locally advanced non-small cell lung cancer (LA-NSCLC). In this study we sought to identify the risk factors for pneumonitis with CRT-ICI therapy in LA-NSCLC cases and determine its impact on survival.

MATERIALS AND METHODS

We conducted a retrospective chart review of 140 patients with LA-NSCLC who underwent curative-intent CRT-ICI with durvalumab between 2018 and 2021. Pneumonitis was diagnosed by a multidisciplinary team of clinical experts. We used multivariable cause-specific hazard models to identify risk factors associated with grade ≥2 pneumonitis. We constructed multivariable Cox proportional hazard models to investigate the impact of pneumonitis on all-cause mortality.

RESULTS

The median age of the cohort was 67 years; most patients were current or former smokers (86%). The cumulative incidence of grade ≥2 pneumonitis was 23%. Among survivors, 25/28 patients had persistent parenchymal scarring. In multivariable analyses, the mean lung dose (hazard ratio 1.14 per Gy, 95% confidence interval 1.03-1.25) and interstitial lung disease (hazard ratio 3.8, 95% confidence interval 1.3-11.0) increased the risk for pneumonitis. In adjusted models, grade ≥2 pneumonitis (hazard ratio 2.5, 95% confidence interval 1.0-6.2, P = 0.049) and high-grade (≥3) pneumonitis (hazard ratio 8.3, 95% confidence interval 3.0-23.0, P < 0.001) were associated with higher all-cause mortality.

CONCLUSIONS

Risk factors for pneumonitis in LA-NSCLC patients undergoing CRT-ICI include the mean radiation dose to the lung and pre-treatment interstitial lung disease. Although most cases are not fatal, pneumonitis in this setting is associated with markedly increased mortality.

Heterogenous lung inflammation CT patterns distinguish pneumonia and immune checkpoint inhibitor pneumonitis and complement blood biomarkers in acute myeloid leukemia: proof of concept

Background

Immune checkpoint inhibitors (ICI) may cause pneumonitis, resulting in potentially fatal lung inflammation. However, distinguishing pneumonitis from pneumonia is time-consuming and challenging. To fill this gap, we build an image-based tool, and further evaluate it clinically alongside relevant blood biomarkers.

Materials and methods

We studied CT images from 97 patients with pneumonia and 29 patients with pneumonitis from acute myeloid leukemia treated with ICIs. We developed a CT-derived signature using a habitat imaging algorithm, whereby infected lungs are segregated into clusters ("habitats"). We validated the model and compared it with a clinical-blood model to determine whether imaging can add diagnostic value.

Results

Habitat imaging revealed intrinsic lung inflammation patterns by identifying 5 distinct subregions, correlating to lung parenchyma, consolidation, heterogenous ground-glass opacity (GGO), and GGO-consolidation transition. Consequently, our proposed habitat model (accuracy of 79%, sensitivity of 48%, and specificity of 88%) outperformed the clinical-blood model (accuracy of 68%, sensitivity of 14%, and specificity of 85%) for classifying pneumonia versus pneumonitis. Integrating imaging and blood achieved the optimal performance (accuracy of 81%, sensitivity of 52% and specificity of 90%). Using this imaging-blood composite model, the post-test probability for detecting pneumonitis increased from 23% to 61%, significantly (p = 1.5E - 9) higher than the clinical and blood model (post-test probability of 22%).

Conclusion

Habitat imaging represents a step forward in the image-based detection of pneumonia and pneumonitis, which can complement known blood biomarkers. Further work is needed to validate and fine tune this imaging-blood composite model and further improve its sensitivity to detect pneumonitis.

Safety, tolerability, and clinical activity of selinexor in combination with pembrolizumab in treatment of metastatic non-small cell lung cancer

BACKGROUND

In lung cancer, overexpression of nuclear export proteins can result in inactivation of critical tumor suppressor proteins and cell-cycle regulators. Selective suppression of nuclear export proteins has immunomodulatory activities. Here, clinical safety and early efficacy data are presented on the combination of pembrolizumab and an oral selective nuclear export inhibitor, selinexor, for the treatment of metastatic non-small cell lung cancer (mNSCLC).

METHODS

The primary objective of this prospective investigator-initiated study was to determine the safety and tolerability of selinexor in combination with pembrolizumab in patients with mNSCLC. Secondary objectives included determination of objective tumor response rate, disease control rate, and progression-free survival duration.

RESULTS

A total of 17 patients were included in the final analysis. Fifteen (88%) received more than two lines of prior systemic therapy and 10 (59%) had prior exposure to anti-PD-1/programmed death-ligand 1 (PD-L1) therapy. The median age was 67.5 years. Ten patients had grade ≥3 adverse events related to selinexor treatment. Responses to treatment occurred in patients who did and did not undergo previous anti-PD-1/PD-L1 therapy and in patients with activating driver mutations. The median overall survival and progression-free survival were 11.4 months (95% CI, 3.4-19.8 months) and 3.0 months (95% CI, 1.7-5.7 months), respectively. The overall response rate was 18% and the 6-month disease control rate was 24%.

CONCLUSIONS

Selinexor in combination with pembrolizumab demonstrated promising antitumor activity in patients with mNSCLC, including those who had previously received anti-PD-1/PD-L1 therapy. The therapy-related toxic effects were consistent with the prior safety data for both drugs, and no overlapping toxic effects were observed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02419495.

PLAIN LANGUAGE SUMMARY

New strategies to prevent or reverse resistance to immune checkpoint inhibitors are under investigation. Selective inhibitors of nuclear export proteins, such as selinexor, can induce restoration of tumor-suppressing pathways and induce potent immunomodulatory activities. This article contains the clinical safety and early efficacy data on the combination of pembrolizumab and selinexor in treatment of metastatic non-small cell lung cancer.

Interleukin-10 in cancer immunotherapy: from bench to bedside

Interleukin (IL)-10 was one of the first cytokines to be recognized. However, its functionality in promoting antitumor immunity was described more recently. Context- and concentration-dependent biological effects are the hallmarks of the pleiotropic role of IL-10. Despite reducing tumor-promoting inflammation, IL-10 may have a role in rejuvenating exhausted tumor-resident T cells. Contrary to the assumption that IL-10 produces an immunosuppressive tumor microenvironment (TME), it promotes activation of tumor-resident CD8+ T cells, which aids tumor rejection. Emerging data from published early-Phase trials have shown mixed results in different tumor types. In this review, we summarize the biological effects of IL-10 and highlight the clinical experience using pegilodecakin.

Immune Checkpoint Inhibitors Suppress Hepatitis C Virus Replication in Infected Patients With Solid Tumors

INTRODUCTION

Data are scarce regarding the virologic impact and safety of immune checkpoint inhibitors (ICI) in patients with chronic hepatitis C virus (HCV) infection. We examined the virologic impact of ICI in HCV-infected patients with solid tumors and their safety.

METHODS

HCV-infected patients with solid tumor treated with ICI at our institution between April 26, 2016, and January 5, 2022, were enrolled in a prospective observational study. The primary outcomes were ICI-induced changes in HCV viremia (HCV inhibition and HCV reactivation) and safety of ICI.

RESULTS

We enrolled 52 consecutive patients with solid tumors treated with ICI. Most were men (41; 79%), White (31; 59%), without cirrhosis (34; 65%), and with HCV genotype 1 (40; 77%). Four patients (7.7%) experienced HCV inhibition while receiving ICI including 1 patient who developed undetectable viremia for 6 months in the absence of direct-acting antivirals (DAA). Two patients (4%) developed HCV reactivation, both while receiving immunosuppressive therapy for ICI-related toxic effects. Adverse events occurred in 36 patients (69%), and 39 of the 47 adverse events (83%) were grade 1-2. Grade 3-4 adverse events occurred in 8 patients (15%), and in all cases, they were related to ICI, not to HCV. No HCV-associated liver failure or death occurred.

DISCUSSION

Inhibition of HCV replication with virologic cure can develop in patients receiving ICI without DAA. HCV reactivation occurs primarily in patients receiving immunosuppressants for ICI-related toxic effects. ICI are safe in HCV-infected patients with solid tumors. Chronic HCV infection should not be considered a contraindication for ICI therapy.

Safety and Efficacy of Immune Checkpoint Inhibitors in Patients with Cancer and Viral Hepatitis: The MD Anderson Cancer Center Experience

BACKGROUND

Despite the clinical benefit of immune checkpoint inhibitors (ICIs), patients with a viral hepatitis have been excluded from clinical trials because of safety concerns. The purpose of this study was to determine the incidence rate of adverse events (AEs) in patients with viral hepatitis who received ICIs for cancer treatment.

MATERIALS AND METHODS

We conducted a retrospective study in patients with cancer and concurrent hepatitis B or C, who had undergone treatment with ICI at MD Anderson Cancer Center from January 1, 2010 to December 31, 2019.

RESULTS

Of the 1076 patients screened, we identified 33 with concurrent hepatitis. All 10 patients with HBV underwent concomitant antiviral therapy during ICI treatment. Sixteen of the 23 patients with HCV received it before the initiation of ICI. The median follow-up time was 33 months (95% CI, 23-45) and the median duration of ICI therapy was 3 months (IQR, 1.9-6.6). Of the 33 patients, 12 (39%) experienced irAEs (immune-related adverse events) of any grade, with 2 (6%) having grade 3 or higher. None of the patients developed hepatitis toxicities.

CONCLUSION

ICIs may be a therapeutic option with an acceptable safety profile in patients with cancer and advanced liver disease.

T-cell receptor beta variable gene polymorphism predicts immune-related adverse events during checkpoint blockade immunotherapy

BACKGROUND

Immune checkpoint inhibitors have revolutionized cancer treatment. However, they are associated with a unique spectrum of side effects, called immune-related adverse events (irAEs), which can cause significant morbidity and quickly progress to severe or life-threatening events if not treated promptly. Identifying predictive biomarkers for irAEs before immunotherapy initiation is therefore a critical area of research. Polymorphisms within the T-cell receptor beta (TCRB) variable (TRBV) gene have been implicated in autoimmune disease and may be mechanistically linked to irAEs. However, the repetitive nature of the TCRB locus and incomplete genome assembly has hampered the evaluation of TRBV polymorphisms in the past.

PATIENTS AND METHODS

We used a novel method for long-amplicon next generation sequencing of rearranged TCRB chains from peripheral blood total RNA to evaluate the link between TRBV polymorphisms and irAEs in patients treated with immunotherapy for cancer. We employed multiplex PCR to create amplicons spanning the three beta chain complementarity-determining regions (CDR) regions to enable detection of polymorphism within the germline-encoded framework and CDR1 and CDR2 regions in addition to CDR3 profiling. Resultant amplicons were sequenced via the Ion Torrent and TRBV allele profiles constructed for each individual was correlated with irAE annotations to identify haplotypes associated with severe irAEs (≥ grade 3).

RESULTS

Our study included 81 patients who had irAEs when treated with immunotherapy for cancer. By using principal component analysis of the 81 TRBV allele profiles followed by k-means clustering, we identified six major TRBV haplotypes. Strikingly, we found that one-third of this cohort possessed a TRBV allele haplotype that appeared to be protective against severe irAEs.

CONCLUSION

The data suggest that long-amplicon TCRB repertoire sequencing can potentially identify TRBV haplotype groups that correlate with the risk of severe irAEs. Germline-encoded TRBV polymorphisms may serve as a predictive biomarker of severe irAEs.

A Phase II Clinical Trial of Pembrolizumab Efficacy and Safety in Advanced Renal Medullary Carcinoma

BACKGROUND

Renal medullary carcinoma (RMC) is one of most aggressive renal cell carcinomas and novel therapeutic strategies are therefore needed. Recent comprehensive molecular and immune profiling of RMC tissues revealed a highly inflamed phenotype, suggesting the potential therapeutic role for immune checkpoint therapies. We present the first prospective evaluation of an immune checkpoint inhibitor in a cohort of patients with RMC.

METHODS

A cohort of patients with locally advanced or metastatic RMC was treated with pembrolizumab 200 mg intravenously every 21 days in a phase II basket trial (ClinicalTrials.gov: NCT02721732). Responses were assessed by irRECIST. Tumor tissues were evaluated for PD-L1 expression and for tumor-infiltrating lymphocyte (TIL) levels. Somatic mutations were assessed by targeted next-generation sequencing.

RESULTS

A total of five patients were treated. All patients had advanced disease, with the majority of patients (60%) having metastatic disease at diagnosis. All patients had rapid disease progression despite pembrolizumab treatment, with a median time to progression of 8.7 weeks. One patient (patient 5) experienced sudden clinical progression immediately after treatment initiation and was thus taken off trial less than one week after receiving pembrolizumab.

CONCLUSIONS

This prospective evaluation showed no evidence of clinical activity for pembrolizumab in patients with RMC, irrespective of PD-L1 or TIL levels.

Ocular Toxicity Profile of Targeted Cancer Therapy (TCT) at a US Tertiary Cancer Center

PURPOSE

 Targeted cancer therapy (TCT) is a significant advancement in oncology with promising survival improvement in patients with cancer and remarkable effects on various cancers. There is evidence suggesting a connection between specific TCT classes and the occurrence of immune-related adverse events (irAEs). Our study aims to investigate the potential ocular toxicities of different classes of TCT, provide a better understanding of these toxicities, and aid in the future development of screening and management recommendations for ocular irAEs.

DESIGN

 Retrospective observational case series.

PARTICIPANTS

 Only ocular immune-related AEs were included in the study; patients on TCT who received a new ophthalmic diagnosis were seen at the MD Anderson Cancer Center.

METHODS

 Between 2010 and 2019, we retrospectively reviewed the medical records of 6,354 patients on TCT at a large US tertiary cancer center.  Results: The criteria for data analysis were met by 1861 patients. TCT was associated with a wide range of class-specific ocular irAEs. There was a statistically significant correlation between ocular toxicity with polytherapy with a p-value of <0.001. Furthermore, there was a statistically significant correlation between toxicity and BRAF, epidermal growth factor receptor (EGFR), and ICI <0.001, <0.001, and 0.006, respectively.  Conclusion: Our cohort is the most extensive case series in English literature, demonstrating the increased risk of class-specific ocular toxicity associated with TCT, which sheds some light on the importance of developing standardized grading criteria and management guidelines.

Phase I/II sequencing study of azacitidine, epacadostat, and pembrolizumab in advanced solid tumors

BACKGROUND

Indoleamine 2,3-dioxygenase 1 (IDO1), an interferon-inducible enzyme, contributes to tumor immune intolerance. Immune checkpoint inhibition may increase interferon levels; combining IDO1 inhibition with immune checkpoint blockade represents an attractive strategy. Epigenetic agents trigger interferon responses and may serve as an immunotherapy priming method. We evaluated whether epigenetic therapy plus IDO1 inhibition and immune checkpoint blockade confers clinical benefit to patients with advanced solid tumors.

METHODS

ECHO-206 was a Phase I/II study where treatment-experienced patients with advanced solid tumors (N = 70) received azacitidine plus an immunotherapy doublet (epacadostat [IDO1 inhibitor] and pembrolizumab). Sequencing of treatment was also assessed. Primary endpoints were safety/tolerability (Phase I), maximum tolerated dose (MTD) or pharmacologically active dose (PAD; Phase I), and investigator-assessed objective response rate (ORR; Phase II).

RESULTS

In Phase I, no dose-limiting toxicities were reported, the MTD was not reached; a PAD was not determined. ORR was 5.7%, with four partial responses. The most common treatment-related adverse events (AEs) were fatigue (42.9%) and nausea (42.9%). Twelve (17.1%) patients experienced ≥1 fatal AE, one of which (asthenia) was treatment-related.

CONCLUSIONS

Although the azacitidine-epacadostat-pembrolizumab regimen was well tolerated, it was not associated with substantial clinical response in patients with advanced solid tumors previously exposed to immunotherapy.

Impact of Biomarker-Matched Therapies on Outcomes in Patients with Sarcoma Enrolled in Early-Phase Clinical Trials (SAMBA 101)

PURPOSE

Developing new therapeutics for any of the more than 100 sarcoma subtypes presents a challenge. After progression from standard therapies, patients with sarcoma may be referred for enrollment in early-phase trials. This study aimed to investigate whether enrollment in biomarker-matched early-phase clinical trials leads to better outcomes for patients with advanced sarcoma.

EXPERIMENTAL DESIGN

In this retrospective analysis, investigational treatment characteristics and longitudinal survival outcomes were analyzed in patients with biopsy-confirmed sarcoma enrolled in early-phase trials at MD Anderson Cancer Center from May 2006 to July 2021.

RESULTS

Five hundred eighty-seven patients were included [405 soft tissue, 122 bone, 60 gastrointestinal stromal tumor (GIST); median of three prior lines of therapy]. Most common subtypes were leiomyosarcoma (17.2%), liposarcoma (14.0%), and GIST (10.2%). Molecular testing was available for 511 patients (87.1%); 221 patients (37.6%) were treated in matched trials. Overall response rate was 13.1% matched compared with 4.9% in unmatched (P < 0.001); the clinical benefit rate at 6 months was 43.9% vs. 19.9% (P < 0.001). Progression-free survival was longer for patients in matched trials (median, 5.5 vs. 2.4 months; P < 0.001), and overall survival was also superior for patients in matched trials (median, 21.5 vs. 12.3 months; P < 0.001). The benefit of enrollment in matched trials was maintained when patients with GIST were excluded from the analysis.

CONCLUSIONS

Enrollment in biomarker-matched early-phase trials is associated with improved outcomes in heavily pretreated patients with metastatic sarcoma. Molecular testing of tumors from patients with advanced sarcoma and enrollment in matched trials is a reasonable therapeutic strategy.

Phase I study of sapanisertib with carboplatin and paclitaxel in mTOR pathway altered solid malignancies

Pre-clinically, the mTORC1/2 inhibitor sapanisertib restored sensitivity to platinums and enhanced paclitaxel-induced cancer cell killing. NCT03430882 enrolled patients with mTOR pathway aberrant tumors to receive sapanisertib, carboplatin and paclitaxel. Primary objective was safety and secondary objectives were clinical response and survival. One patient had a dose-limiting toxicity at dose level 4. There were no unanticipated toxicities. Grade 3-4 treatment-related adverse events included anemia (21%), neutropenia (21%), thrombocytopenia (10.5%), and transaminitis (5%). Of 17 patients evaluable for response, 2 and 11 patients achieved partial response and stable disease, respectively. Responders included a patient with unclassified renal cell carcinoma harboring EWSR1-POU5F1 fusion and a patient with castrate resistant prostate cancer harboring PTEN loss. Median progression free survival was 3.84 months. Sapanisertib in combination with carboplatin plus paclitaxel demonstrated a manageable safety profile, with preliminary antitumor activity observed in advanced malignancies harboring mTOR pathway alterations.

Phase 1b study of combined selinexor and eribulin for the treatment of advanced solid tumors and triple-negative breast cancer

BACKGROUND

Selinexor (KPT-330) is a potent inhibitor of exportin 1 (XPO1), in turn inhibiting tumor growth. Selinexor enhances the antitumor efficacy of eribulin in triple-negative breast cancer (TNBC) in vitro and in vivo. Given the unmet medical need in TNBC and sarcoma, the authors explored the safety and efficacy of this combination.

METHODS

The authors conducted a phase 1b trial of combined selinexor and eribulin using a 3 + 3 dose-escalation design in patients who had advanced solid tumors and in those who had TNBC in a dose-expansion cohort.

RESULTS

Patients with TNBC (N = 19), sarcoma (N = 9), and other cancers (N = 3) were enrolled in the dose-escalation cohort (N = 10) and in the dose-expansion cohort (N = 21). The median number lines of prior therapy received was four (range, from one to seven prior lines). The most common treatment-related adverse events for selinexor were nausea (77%), leukopenia (77%), anemia (68%), neutropenia (68%), and fatigue (48%). One dose-limiting toxicity occurred at the first dose level with prolonged grade 3 neutropenia. The recommended phase 2 dose was 80 mg of selinexor orally once per week and 1 mg/m² eribulin on days 1 and 8 intravenously every 3 weeks. The objective response rate (ORR) was 10% in three patients. In the dose-escalation cohort, the ORR was 10%, whereas six patients with had stable disease. In the TNBC dose-expansion cohort (n = 18), ORR was 11%, and there were two confirmed partial responses with durations of 10.8 and 19.1 months (ongoing).

CONCLUSIONS

Selinexor and eribulin had an acceptable toxicity profile and modest overall efficacy with durable responses in select patients.

PLAIN LANGUAGE SUMMARY

Effective therapies for advanced, triple-negative breast cancer and sarcoma represent an unmet need. Exportin 1 is associated with the transport of cancer-related proteins. Preclinical studies have demonstrated tumor growth inhibition and enhanced tumor sensitivity in patients who receive selinexor combined with eribulin. In this phase 1b study, the authors evaluated the safety profile and clinical activity of the combination of selinexor, a potent oral inhibitor of exportin 1, and eribulin in patients with advanced cancers enriched for triple-negative breast cancer or sarcoma. The combination was well tolerated; most adverse events were mild or moderate, reversible, and managed with dose modifications or growth factor support. The combination of selinexor and eribulin produced an antitumor response, particularly in some patients with triple-negative breast cancer. This work lays the foundation for prospective investigations of the role of selinexor and eribulin in the treatment of triple-negative breast cancer.

Abstract 6181: Dynamic changes in monocyte and reticulocyte counts predict mechanism-based anemia development and recovery during ATR inhibitor treatment in phase I/II trials

Introduction: Clinical trials are exploring ATR inhibitors (ATRi) in genomically selected contexts. However, dose-dependent anemia has limited the therapeutic index of this class. We hypothesized that monocytes and reticulocytes are more vulnerable to ATRi due to their lack of base excision repair and high levels of oxidative stress, respectively. We sought to examine the kinetics of decline and recovery of red blood cell (RBC) and reticulocyte indices, in relation to hemoglobin (Hb), in the first 28 days after ATRi initiation.

Methods: We retrospectively retrieved peripheral blood cell indices from complete blood count (CBC) reports of patients (pts) pre- and during treatment with an oral ATRi on phase I/II trials at our center. Pts received ATRi monotherapy or in combination with a PARP inhibitor (ATRi+PARPi) in dose-escalation and expansion cohorts, which included ATRi at potentially toxic doses. We applied linear mixed effect models to evaluate the joint evolution of Hb and other RBC or reticulocyte indices over time via bivariate analysis. A random intercept was included in the model to account for the longitudinal nature of the data and a variance component option for the covariance structure was specified to model a different variance component for each index of interest. To assess if Hb decline was preceded by decline in the index of interest from baseline, piecewise regression models were used to estimate break points, defined as the time point where the fitted functions intersect, of each index. Log transformed data with a base of 2, were noted to have more symmetric distributions, and were used in the analyses. The time variable assessed was days from cycle 1 day 1 of ATRi. A two-sided p value &lt;0.05 was considered statistically significant.

Results: 35,007 indices from 1,843 CBC of 119 pts treated with an ATRi from 10/2017 to 1/2022 were analyzed. 110 (92.4%) pts received ATRi, 9 (7.6%) received ATRi+PARPi. Monocytes (-0.120 vs -0.022, p &lt;0.0001) and reticulocytes (-0.140 vs -0.022, p &lt;0.0001) declined at a faster rate compared with Hb. Time to monocyte and reticulocyte nadir after ATRi initiation was 8.9 and 5.8 days, respectively, while time to Hb nadir was 19.5 days. Conversely, RBC (-0.020 vs -0.023, p=0.410), MCV (-0.002 vs -0.022, p &lt;0.0001) and MCH (-0.001 vs -0.022, p&lt;0.0001) declined at a slower rate than Hb. Time to RBC, MCV and MCH nadir after ATRi initiation was 26.3, 18.7 and 15.0 days, respectively. After reaching their individual index nadir, monocytes (0.004 vs 0.001, p &lt;0.0001) and reticulocytes (0.005 vs 0.0005, p &lt;0.0001) increased more quickly than Hb.

Conclusions: Charting the kinetics of CBC index evolution in relation to Hb identified peripheral monocytes and reticulocytes as relevant blood indices that herald Hb decline. Our findings may inform patient monitoring strategies to mitigate hematologic toxicity on future ATRi trials.

Citation Format: Natalie Y. Ngoi, Heather Y. Lin, Ecaterina Dumbrava, Siqing Fu, Daniel D. Karp, Aung Naing, Shubham Pant, Sarina A. Piha-Paul, Jordi Rodon, Vivek Subbiah, Apostolia M. Tsimberidou, Erick Campbell, Samuel Urrutia, David S. Hong, Funda Meric-Bernstam, Ying Yuan, Timothy A. Yap. Dynamic changes in monocyte and reticulocyte counts predict mechanism-based anemia development and recovery during ATR inhibitor treatment in phase I/II trials. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6181.

Applications and clinical trial landscape using Toll-like receptor agonists to reduce the toll of cancer

Toll-like receptors (TLRs), which serve as a bridge between innate and adaptive immunity, may be viable treatment targets. TLRs are the first line of defense against microbes and activate signaling cascades that induce immune and inflammatory responses. Patients with "hot" versus "cold" tumors may respond more favorably to immune checkpoint inhibition, and through their downstream effects, TLR agonists have the potential to convert "cold tumors" into "hot tumors" making TLRs in combination with immune checkpoint inhibitors, potential targets for cancer therapies. Imiquimod is a topical TLR7 agonist, approved by the FDA for antiviral and skin cancer treatments. Other TLR adjuvants are used in several vaccines including Nu Thrax, Heplisav, T-VEC, and Cervarix. Many TLR agonists are currently in development as both monotherapy and in combination with immune checkpoint inhibitors. In this review, we describe the TLR agonists that are being evaluated clinically as new therapies for solid tumors.

BRAF v600E-mutant cancers treated with vemurafenib alone or in combination with everolimus, sorafenib, or crizotinib or with paclitaxel and carboplatin (VEM-PLUS) study

Combined BRAF + MEK inhibition is FDA approved for BRAF V600E-mutant solid tumors except for colorectal cancer. However, beyond MAPK mediated resistance several other mechanisms of resistance such as activation of CRAF, ARAF, MET, P13K/AKT/mTOR pathway exist among other complex pathways. In the VEM-PLUS study, we performed a pooled analysis of four phase one studies evaluating the safety and efficacy of vemurafenib monotherapy and vemurafenib combined with targeted therapies (sorafenib, crizotinib, or everolimus) or carboplatin plus paclitaxel in advanced solid tumors harboring BRAF V600 mutations. When vemurafenib monotherapy was compared with the combination regimens, no significant differences in OS or PFS durations were noted, except for inferior OS in the vemurafenib and paclitaxel and carboplatin trial (P = 0.011; HR, 2.4; 95% CI, 1.22-4.7) and in crossover patients (P = 0.0025; HR, 2.089; 95% CI, 1.2-3.4). Patients naïve to prior BRAF inhibitors had statistically significantly improved OS at 12.6 months compared to 10.4 months in the BRAF therapy refractory group (P = 0.024; HR, 1.69; 95% CI 1.07-2.68). The median PFS was statistically significant between both groups, with 7 months in the BRAF therapy naïve group compared to 4.7 months in the BRAF therapy refractory group (P = 0.016; HR, 1.80; 95% CI 1.11-2.91). The confirmed ORR in the vemurafenib monotherapy trial (28%) was higher than that in the combination trials. Our findings suggest that, compared with vemurafenib monotherapy, combinations of vemurafenib with cytotoxic chemotherapy or with RAF- or mTOR-targeting agents do not significantly extend the OS or PFS of patients who have solid tumors with BRAF V600E mutations. Gaining a better understanding of the molecular mechanisms of BRAF inhibitor resistance, balancing toxicity and efficacy with novel trial designs are warranted.

Baseline extracellular vesicle TGF-β is a predictive biomarker for response to immune checkpoint inhibitors and survival in non-small cell lung cancer

BACKGROUND

Immune-checkpoint inhibitors (ICIs) are an effective therapeutic strategy, improving the survival of patients with lung cancer compared with conventional treatments. However, novel predictive biomarkers are needed to stratify which patients derive clinical benefit because the currently used and highly heterogenic histological PD-L1 has shown low accuracy. Liquid biopsy is the analysis of biomarkers in body fluids and represents a minimally invasive tool that can be used to monitor tumor evolution and treatment effects, potentially reducing biases associated with tumor heterogeneity associated with tissue biopsies. In this context, cytokines, such as transforming growth factor-β (TGF-β), can be found free in circulation in the blood and packaged into extracellular vesicles (EVs), which have a specific delivery tropism and can affect in tumor/immune system interaction. TGF-β is an immunosuppressive cytokine that plays a crucial role in tumor immune escape, treatment resistance, and metastasis. Thus, we aimed to evaluate the predictive value of circulating and EV TGF-β in patients with non-small-cell lung cancer receiving ICIs.

METHODS

Plasma samples were collected in 33 patients with advanced non-small-cell lung cancer before and during treatment with ICIs. EV were isolated from plasma by serial ultracentrifugation methods and circulating and EV TGF-β expression levels were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Baseline high expression of TGF-β in EVs was associated with nonresponse to ICIs as well as shorter progression-free survival and overall survival, outperforming circulating TGF-β levels and tissue PD-L1 as a predictive biomarker.

CONCLUSION

If validated, EV TGF-β could be used to improve patient stratification, increasing the effectiveness of treatment with ICIs and potentially informing combinatory treatments with TGF-β blockade.

PLAIN LANGUAGE SUMMARY

Treatment with immune-checkpoint inhibitors (ICIs) has improved the survival of some patients with lung cancer. However, the majority of patients do not benefit from this treatment, making it essential to develop more reliable biomarkers to identify patients most likely to benefit. In this pilot study, the expression of transforming growth factor-β (TGF-β) in blood circulation and in extracellular vesicles was analyzed. The levels of extracellular vesicle TGF-β before treatment were able to determine which patients would benefit from treatment with ICIs and have a longer survival with higher accuracy than circulating TGF-β and tissue PD-L1, which is the currently used biomarker in clinical practice.

Examining Stripes on a Herd of Zebras: Impact of Genomic Matching for Ultrarare Sarcomas in Phase 1 Clinical Trials (SAMBA 102)

PURPOSE

Recently, the Connective Tissue Oncology Society published consensus guidelines for recognizing ultrarare sarcomas (URS), defined as sarcomas with an incidence ≤1 per 1,000,000. We assessed the outcomes of 56 patients with soft tissue, and 21 with bone sarcomas, enrolled in Phase 1 trials.

EXPERIMENTAL DESIGN

In this Sarcoma-Matched Biomarker Analysis (SAMBA-102 study), we reviewed records from patients on Phase 1 trials at the University of Texas MD Anderson Cancer Center between January 2013 and June 2021.

RESULTS

Among 587 sarcomas, 106 (18.1%) were classified as URS. Fifty (47%) were male, and the median age was 44.3 years (range, 19-82). The most common subtypes were alveolar soft part sarcoma (ASPS), chordoma, dedifferentiated chondrosarcoma, and sclerosing epithelioid fibrosarcoma. Compared with common sarcomas, median OS was similar 16.1 months [95% confidence interval (CI), 13.6-17.5] versus 16.1 (95% CI, 8.2-24.0) in URS (P = 0.359). Objective response to treatment was higher in URS 13.2% (n = 14/106) compared with common sarcomas 6.9% (n = 33/481; P = 0.029). Median OS for those treated on matched trials was 27.3 months (95% CI, 1.9-52.7) compared with 13.4 months (95% CI, 6.3-20.6) for those not treated on matched trials (P = 0.291). Eight of 33 (24%) molecularly matched treatments resulted in an objective response, whereas 6 of 73 unmatched treatments (8.2%) resulted in an objective response (P = 0.024). Clinical benefit rate was 36.4% (12/33) in matched trials versus 26.0% (19/73) in unmatched trials (P = 0.279).

CONCLUSIONS

The results demonstrate the benefit of genomic selection in Phase 1 trials to help identify molecular subsets likely to benefit from targeted therapy.

Predictors of Oncologic Outcome in Patients Receiving Phase I Investigational Therapy for Recurrent or Metastatic Cervical Cancer

Introduction

We aimed to identify clinical, pathologic, and treatment factors that are predictive of response and survival in patients with cervical cancer referred to phase I clinical trials.

Methods

Patients with cervical cancer who received at least one dose of a phase I investigational agent at our institution between 2014 and 2022 were included. The log-rank test was used to analyze differences in progression-free survival (PFS) and overall survival (OS), and multivariable regression analysis was performed.

Results

We included 65 patients with a median age of 41 years (range, 20-74), 3 prior therapies (range, 1-7), and 67.7% squamous carcinoma. The rate of distant metastasis at trial entry was 84.6%. The most common molecular alterations included PIK3CA (46.5%), PD-L1+ (46.2%), EPH (30.0%), and CREBBP (23.1%); 23.1% had received a prior checkpoint inhibitor. Phase I trials were for immunotherapy (58.5%) or targeted therapy (41.5%). The rate of biomarker matching was 21.5%. For all patients, median PFS was 3.6 months (95% CI, 2.0-5.2) and OS was 9.3 months (95% CI, 7.0-10.6). Factors at study entry associated with worse survival were presence of bone metastasis (PFS 1.6 vs 4.4 months: hazard ratio [HR], 2.8; p = 0.001; OS 3.8 vs 10.0 months: HR, 3.9; p < 0.0001) and absolute lymphocyte count below 1000/μL (PFS 1.8 vs 5.2 months: HR, 2.9; p = 0.0004; OS 7.0 vs 10.6 months: HR, 3.2; p = 0.0009). Factors associated only with worse OS were absolute neutrophil count above 4700/μL, hemoglobin below 10.5 g/dL, and smoking status. Grade 3+ treatment-related adverse events were seen in 16.9% of cases.

Conclusion

Bone metastasis and absolute lymphocyte count below normal range at phase I study entry portend poor survival in patients with recurrent or metastatic cervical cancer.

Selinexor in combination with weekly paclitaxel in patients with metastatic solid tumors: Results of an open label, single-center, multi-arm phase 1b study with expansion phase in ovarian cancer

OBJECTIVE

Selinexor is a first-in-class, oral selective inhibitor of nuclear export (SINE) compound which blocks Exportin-1 (XPO1). Our objective was to determine maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of selinexor and weekly paclitaxel.

METHODS

This was an open label, single-center, multi-arm phase 1b study utilizing a "3 + 3" design and a "basket-type" expansion in recurrent solid tumors. Selinexor (60 mg or 80 mg twice weekly orally) and weekly paclitaxel (80 mg IV 2 week on, 1 week off) were one of 13 parallel arms. Efficacy was evaluated using RECIST version 1.1.

RESULTS

All 35 patients treated were evaluable for toxicity and 31 (88%) were evaluable for response. Patient diagnoses included platinum-resistant/refractory ovarian (n = 28), breast (n = 4), prostate (n = 2), and cervical (n = 1) cancer. Patients had a median of four prior therapies (range 1-10), and 47% had a prior taxane in the recurrent setting. There were no DLTs and 60 mg was chosen as the RP2D due to long-term tolerability. Ninety-seven percent of patients had at least one treatment-emergent adverse event (TEAE), and the most common grade ≥ 3 TEAE were neutropenia (46%), anemia (31%), and nausea (21%). Among 24 evaluable patients with ovarian cancer, response rate was 17%, CBR was 58%, and median PFS was 6.8 months (95% CI 3.7, not reached (NR)).

CONCLUSIONS

Oral selinexor in combination with weekly paclitaxel demonstrated promising clinical activity with manageable toxicity. This combination should be considered for further exploration in a randomized study, especially in ovarian malignancies.

Cancer: slaying the nine-headed Hydra

Modern medicine continues to evolve, and the treatment armamentarium for various diseases grows more individualized across a breadth of medical disciplines. Cure rates for infectious diseases that were previously pan-fatal approach 100% because of the identification of the specific pathogen(s) involved and the use of appropriate combinations of drugs, where needed, to completely extinguish infection and hence prevent emergence of resistant strains. Similarly, with the assistance of technologies such as next-generation sequencing and immunomic analysis as part of the contemporary oncology armory, therapies can be tailored to each tumor. Importantly, molecular interrogation has revealed that metastatic cancers are distinct from each other and complex. Therefore, it is conceivable that rational personalized drug combinations will be needed to eradicate cancers, and eradication will be necessary to mitigate clonal evolution and resistance.

Complex I inhibitor of oxidative phosphorylation in advanced solid tumors and acute myeloid leukemia: phase I trials

Although targeting oxidative phosphorylation (OXPHOS) is a rational anticancer strategy, clinical benefit with OXPHOS inhibitors has yet to be achieved. Here we advanced IACS-010759, a highly potent and selective small-molecule complex I inhibitor, into two dose-escalation phase I trials in patients with relapsed/refractory acute myeloid leukemia (NCT02882321, n = 17) and advanced solid tumors (NCT03291938, n = 23). The primary endpoints were safety, tolerability, maximum tolerated dose and recommended phase 2 dose (RP2D) of IACS-010759. The PK, PD, and preliminary antitumor activities of IACS-010759 in patients were also evaluated as secondary endpoints in both clinical trials. IACS-010759 had a narrow therapeutic index with emergent dose-limiting toxicities, including elevated blood lactate and neurotoxicity, which obstructed efforts to maintain target exposure. Consequently no RP2D was established, only modest target inhibition and limited antitumor activity were observed at tolerated doses, and both trials were discontinued. Reverse translational studies in mice demonstrated that IACS-010759 induced behavioral and physiological changes indicative of peripheral neuropathy, which were minimized with the coadministration of a histone deacetylase 6 inhibitor. Additional studies are needed to elucidate the association between OXPHOS inhibition and neurotoxicity, and caution is warranted in the continued development of complex I inhibitors as antitumor agents.

Phase 1/2 study of epacadostat in combination with durvalumab in patients with metastatic solid tumors

BACKGROUND

Targeting programmed cell death protein 1 (PD-1) and indoleamine 2,3-dioxygenase (IDO1) pathways is an appealing option for cancer treatment.

METHODS

The open-label, phase 1/2 ECHO-203 study evaluated the safety, tolerability, and efficacy of the IDO1 inhibitor epacadostat in combination with durvalumab, a human anti-PD-L1 monoclonal antibody in adult patients with advanced solid tumors.

RESULTS

The most common treatment-related adverse events were fatigue (30.7%), nausea (21.0%), decreased appetite (13.1%), pruritus (12.5%), maculopapular rash (10.8%), and diarrhea (10.2%). Objective response rate (ORR) in the overall phase 2 population was 12.0%. Higher ORR was observed in immune checkpoint inhibitor (CPI)-naïve patients (16.1%) compared with patients who had received previous CPI (4.1%). Epacadostat pharmacodynamics were evaluated by comparing baseline kynurenine levels with those on therapy at various time points. Only the 300-mg epacadostat dose showed evidence of kynurenine modulation, albeit unsustained.

CONCLUSIONS

Epacadostat plus durvalumab was generally well tolerated in patients with advanced solid tumors. ORR was low, and evaluation of kynurenine concentration from baseline to cycle 2, day 1, and cycle 5, day 1, suggested >300 mg epacadostat twice daily is needed to ensure sufficient drug effect.

CLINICAL TRIAL INFORMATION

A study of epacadostat (INCB024360) in combination with durvalumab (MEDI4736) in subjects with selected advanced solid tumors (ECHO-203) (NCT02318277).

Epacadostat Plus Pembrolizumab and Chemotherapy for Advanced Solid Tumors: Results from the Phase I/II ECHO-207/KEYNOTE-723 Study

BACKGROUND

Epacadostat, an oral, selective inhibitor of IDO1, has shown activity when administered with pembrolizumab. We evaluated the addition of chemotherapy to epacadostat and pembrolizumab in patients with advanced or metastatic solid tumors. One proposed mechanism of resistance to PD-1 checkpoint inhibition is through immunosuppression mediated by L-kynurenine. IDO1, indoleamine-2,3-dioxygenase 1 is the rate-limiting enzyme catalyzing the conversion of L-tryptophan to L-kynurenine. If IDO1 is a mechanism of tumor escape from checkpoint inhibition, then addition of an IDO1 inhibitor with a PD-1 checkpoint inhibitor could enable tumor response to immunotherapy.

METHODS

Patients received one of 7 tumor-appropriate chemotherapy regimens. Pembrolizumab 200 mg was infused intravenously every 3 weeks. Epacadostat 100 mg was administered orally twice daily. The primary objectives of phase I were determining safety/tolerability and defining the maximum tolerated or pharmacologically active dose of epacadostat. Phase II of the study was designed to enroll efficacy-expansion cohorts and to assess changes in the tumor and tumor microenvironment via mandatory-biopsy cohorts.

RESULTS

A total of 70 patients were enrolled. Twelve patients were enrolled in the phase II mandatory-biopsy cohorts. Due to early study closure, efficacy expansion did not enroll. Grades 3 and 4 treatment-emergent adverse events (TEAEs) occurred in 78.6% of patients. Neutropenia and disease progression were the only grades 3 and 4 TEAEs reported in ≥10.0% of patients. One treatment-related death was reported. The ORR was 31.4% across all treatment groups.

CONCLUSION

The combination of epacadostat 100 mg bid with pembrolizumab and chemotherapy had an acceptable safety profile. This regimen showed antitumor activity across multiple types of advanced or metastatic solid tumors (ClinicalTrials.gov Identifier: NCT03085914).

Patient-reported symptom burden in patients with rare cancers receiving pembrolizumab in a phase II Clinical Trial

Patients with rare solid tumors treated on early phase trials experience toxicities from their tumors and treatments. However, limited data exist to describe the detailed symptom burden suffered by these patients, particularly those with rare solid tumors treated with immunotherapy. We performed a prospective longitudinal study to capture patient-reported symptom burden. Patients completed the validated MD Anderson Symptom Inventory (MDASI)—Immunotherapy with 20 symptoms including 7 immunotherapy-specific items and 6 interference items at baseline and weekly thereafter for up to 9 weeks. Symptoms and interference were rated on 0–10 scales (0 = none or no interference, 10 = worst imaginable or complete interference). Group-based trajectory modelling determined higher and lower symptom groups. A total of 336 MDASI questionnaires were completed by 53 patients (mean age 55.4y, 53% male) with advanced rare cancers receiving pembrolizumab in a Phase II clinical trial. Symptoms reported as most severe over the course of the treatment over 9 weeks were fatigue [mean (M) = 3.8, SD = 2.3], pain (M = 3.7, SD = 2.9), disturbed sleep (M = 2.7, SD = 2.3), drowsiness (M = 2.6, SD = 2.0) and lack of appetite (M = 2.5, SD = 2.1). Pain in the abdomen (M = 2.2, SD = 2.4), rash (M = 1.1, SD = 1.8) and diarrhea (M = 0.9, SD = 1.5) were less severe. Interference with walking was rated the highest (M = 3.4, SD = 2.8) and relations with others was rated the lowest (M = 2.1, SD = 2.6). Using a composite score based on the five most severe symptoms (fatigue, pain, lack of appetite, feeling drowsy and sleep disturbance), 43% were classified into the high symptom burden group. Using a score based on immunotherapy-specific symptoms (e.g., rash, diarrhea) 33% of patients were included in the high symptom group. Symptom burden stayed relatively stable in the high- and low-symptom burden patient groups from baseline through 9 weeks. Some patients with rare malignancies experienced high symptom burden even at baseline. In patients with rare cancers, symptom trajectories stayed relatively stable over nine weeks of treatment with pembrolizumab.

Trial registration: ClinicalTrials.gov identifier: NCT02721732.

Clinical Outcomes of Patients with Recurrent Microsatellite-Stable Endometrial Cancer in Early-Phase Immunotherapy Clinical Trials

Simple Summary

There is a crucial need to improve treatment regimens in patients with recurrent endometrial cancer. Although immunotherapy treatments have shown impressive benefit in microsatellite instability-high endometrial cancer, they have been less predictable in the majority of endometrial cancers, which are microsatellite stable. Our aim was to characterize clinical outcomes in patients with recurrent microsatellite stable endometrial cancer treated in early-phase immunotherapy clinical trials in order unravel treatment regimens that would improve response and survival. Our findings suggest that utilizing immunotherapy in combination with other non-immunotherapy agents resulted in greater duration of disease control and improved survival outcomes compared to immunotherapy only (monotherapy) or in combination with other immunotherapy agents. Future studies are needed to validate these findings.

Abstract

Recurrent microsatellite stable (MSS) endometrial cancer has poor response to conventional therapy and limited efficacy with immune checkpoint monotherapy. We conducted a retrospective study of recurrent MSS endometrial cancer patients enrolled in immunotherapy-based clinical trials at MD Anderson Cancer Center between 1 January 2010 and 31 December 2019. Patients were evaluated for radiologic response using RECIST 1.1 criteria, progression-free survival (PFS), and overall survival (OS). Thirty-five patients were treated with immune checkpoint inhibitors: 8 with monotherapy, 17 with immunotherapy (IO) in combination with another IO-only, and 10 with IO in combination with non-IO therapy. Among those treated with combination IO plus non-IO therapy, one had a partial response but 50% had clinical benefit. Patients who received combination IO plus non-IO therapy had improved PFS compared to those who received monotherapy (HR 0.56, 95% CI 0.33–0.97; p = 0.037) or combination IO-only therapy (HR 0.36, 95% CI 0.15–0.90; p = 0.028) and had improved OS when compared to monotherapy after adjusting for prior lines of therapy (HR 0.50, 95% CI 0.27–0.95; p = 0.036). The potential beneficial clinical outcomes of combination IO plus non-IO therapy in MSS endometrial cancer should be validated in a larger study.

Longitudinal Monitoring of Circulating Tumor DNA to Predict Treatment Outcomes in Advanced Cancers

PURPOSE

The response to cancer therapies is typically assessed with radiologic imaging 6-10 weeks after treatment initiation. Circulating tumor DNA (ctDNA), however, has a short half-life, and dynamic changes in ctDNA quantity may allow for earlier assessment of the therapeutic response.

METHODS

Patients with advanced solid tumors referred to the Department of Investigational Cancer Therapeutics at The University of Texas MD Anderson Cancer Center were invited to participate in a liquid biopsy protocol for which serial blood samples were collected before, during, and after systemic therapy. We isolated ctDNA from serially collected plasma samples at baseline, mid-treatment, and first restaging. Genomically informed droplet digital polymerase chain reaction (ddPCR) was performed, and ctDNA quantities were reported as aggregate variant allele frequencies for all detected molecular aberrations.

RESULTS

We included 204 patients receiving 260 systemic therapies. The ctDNA detection rate was higher in progressors (patients with progressive disease) compared with nonprogressors (patients with stable disease, partial responses, or complete responses) at all time points (P < .009). Moreover, ctDNA detection was associated with a shorter median time-to-treatment failure (P ≤ .001). Positive delta and slope values for changes in ctDNA quantity were more frequent in progressors (P ≤ .03 and P < .001, respectively) and were associated with a shorter median time-to-treatment failure (P ≤ .014 and P < .001, respectively). Increasing ctDNA quantity was predictive of clinical and/or radiologic progressive disease in 73% of patients (median lead time, 23 days).

CONCLUSION

Detection of ctDNA and early dynamic changes in its quantity can predict the clinical outcomes of systemic therapies in patients with advanced solid tumors.

Abstract CT213: A multicenter phase 1a/b study of NG-350A, a tumor-selective anti-CD40-antibody expressing adenoviral vector, and pembrolizumab in patients with metastatic or advanced epithelial tumors (FORTIFY)

Background: The efficacy of immune checkpoint inhibitors is often limited by immunosuppressive tumor microenvironments (TME) and novel combination therapies are required to overcome resistance. NG-350A is a novel T-SIGn (Tumor-Specific Immuno Gene) adenoviral vector that expresses a fully human agonistic IgG anti-CD40 antibody to promote innate and adaptive immune responses. Additionally, NG-350A selectively replicates in tumor cells, allowing IV dosing to be coupled with local transgene expression in the TME, thereby targeting all tumor lesions while limiting systemic exposure. Through these immunostimulatory effects the vector is designed to re-program ‘cold’ TMEs to allow functional anti-cancer immune responses. Data from an ongoing study with IV NG-350A monotherapy have shown promising tolerability, as well as prominent and sustained elevations in inflammatory cytokines (IL-2, IFNγ, IL-17A, IL-2 and IFNα2) consistent with the mechanism of action of anti-CD40 in stimulating TME re-programming [Naing 2021]. Based on these promising initial data, we designed a study to further assess the safety, tolerability and preliminary efficacy of NG-350A + pembrolizumab.

Methods: FORTIFY (NCT05165433) is an open-label, dose-escalating, phase 1a/b study of NG-350A + pembrolizumab. Eligible patients have advanced/metastatic epithelial tumors that have progressed after ≥1 line of systemic therapy and are incurable by local therapy. Patients eligible for phase 1a must have experienced failure of prior PD-1/PD-L1 inhibition as part of any prior line of therapy; patients eligible for phase 1b must have primary resistance to PD-1/PD-L1 inhibition. During phase 1a, up to 30 patients will receive escalating doses of IV NG-350A (Bayesian Optimal Interval design) to a maximum of 1 × 1012 viral particles (vp) on Day 1 and 1 × 1013 vp on Days 3 and 5 (1 cycle). Patients will receive a fixed-dose of pembrolizumab (200 mg IV) on Day 15 and then every 3 weeks thereafter for up to 35 cycles. Phase 1b will further investigate the efficacy/safety of the selected regimen in up to 3 tumor-specific cohorts using a Simon 2-stage design. Co-primary objectives are to characterize the safety and tolerability of NG-350A + pembrolizumab and to identify a recommended dose. Preliminary efficacy and immunogenicity are secondary endpoints. Pharmacodynamic outcomes will be assessed using tumor tissues and blood. Analyses of tumor tissue (serial biopsies at baseline and Day 15 of cycles 1-3 [cycles 1-2 only in Phase 1b]) will explore virus replication, transgene expression and immune/inflammatory responses. Analyses of serial blood samples will explore cytokine production and changes in peripheral immune cell subsets. Recruitment is expected to begin in Q1 2022.

Citation Format: Tom Lillie, Mark O'Hara, Christian Ottensmeier, Eileen Parkes, Lee Rosen, David Krige, Marya Chaney, Jo Carter, Vladimir Evilevitch, Matthew Thomas, Aung Naing. A multicenter phase 1a/b study of NG-350A, a tumor-selective anti-CD40-antibody expressing adenoviral vector, and pembrolizumab in patients with metastatic or advanced epithelial tumors (FORTIFY) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT213.

Abstract 5237: B-Raf V600E harboring non-melanoma cancers treated with Vemurafenib monotherapy and in combination with Everolimus/Sorafenib/Crizotinib/Paclitaxel+ Carboplatin: A pooled analysis of five phase 1/2 studies

BACKGROUND: BRAF V600 mutations are driver oncogenes in multiple human cancers. Given complex resistance mechanisms beyond combined MEK inhibition, limited data exists to evaluate combinations with CRAF/ARAF/MET/mTOR inhibitors and cytotoxic chemotherapy in sustaining response and overcoming resistance. We explore patient outcomes comparing vemurafenib monotherapy with the above combination therapies in this analysis.

METHODS: A pooled analysis of 5 phase 1/2 clinical trials containing vemurafenib was conducted between January 2012 and October 2020 in BRAF V600E mutant advanced or metastatic tumors. Overall survival (OS) and Progression free survival (PFS) in vemurafenib monotherapy (V) arm compared with vemurafenib + crizotinib (VC), vemurafenib + sorafenib (VS), vemurafenib + everolimus (VE) and vemurafenib + paclitaxel + carboplatin (VPC) arms were assessed. Objective Response Rate (ORR) and Clinical Benefit Rate (CBR=CR+PR+SD≥6 months) and safety profile of combination arms were also explored.

RESULTS: 99 patients were enrolled across 5 studies. Median age was 57 years with 78% of ECOG 1 and M:F ratio at 1:1. Tumor types included NSCLC (13%), Thyroid cancer (12%), Low and High-grade Gliomas (7%), Colorectal cancer (6%), Cholangiocarcinoma (5%) and ECD (3%). V arm derived greatest clinical benefit with median OS at 21 months while addition of PC arm dropped median OS to 2 months. Inferior OS was seen in VPC arm when compared to V arm (p=0.00616). Median PFS peaked at 11 months in VC arm versus 3 months for the VPC arm. Of 85 evaluable patients, 2 complete responses were noted in the V (n=25) and VPC (n=14) arms and 8 Partial Responses (PR) were noted with 5 (18%) patients with NSCLC in V arm followed by 4 PRs in the VC (n=12) arm. PR rates were equally seen in the other arms. ORR (36%) and CBR (40%) rates were the highest for the V arm. G3/G4 treatment related adverse events with neutropenia (63%), thrombocytopenia (50%) and fatigue (63%) were highest in VPC. 1 patient died from G4 thrombocytopenia with intracranial hemorrhage in the VPC arm.

CONCLUSIONS: No significant added clinical benefit was noted when vemurafenib was combined with other targeted agents or cytotoxic therapy. Combinations resulted in poor tolerance and need for dose reductions compromising clinical efficacy. Prospective studies to analyze resistance mechanisms to BRAF inhibitor therapy in BRAF+ tumors and in real time tailoring therapy based on co-occuring alterations is warranted.

Citation Format: Blessie Elizabeth Nelson, Jason Roszik, Filip Janku, David Hong, Shumei Kato, Aung Naing, Sarina Piha-Paul, Siqing Fu, Apostolia Tsimberidou, Maria Cabanillas, Naifa Busaidy, Milind Javle, Lauren Byers, John Heymach, Funda Meric-Bernstam, Vivek Subbiah. B-Raf V600E harboring non-melanoma cancers treated with Vemurafenib monotherapy and in combination with Everolimus/Sorafenib/Crizotinib/Paclitaxel+ Carboplatin: A pooled analysis of five phase 1/2 studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5237.

Abstract CT250: A first-in-human phase 1 study of NL-201 in patients with relapsed or refractory cancer

Background: NL-201 is a selective and long-acting computationally designed alpha-independent agonist of the IL-2 and IL-15 receptors, which share beta and gamma signaling subunits. NL-201 is being developed as a potent activator of CD8+ T cells and NK cells for cancer immunotherapy. Binding to the beta and gamma subunits stimulates dose-dependent expansion and tumor infiltration of cytotoxic CD8+ T cells and NK cells, thereby enhancing the immune response in the tumor. The absence of binding to the IL-2 alpha subunit reduces the undesirable effects of traditional IL-2 therapies, such as vascular leak syndrome and expansion of immunosuppressive regulatory T cells. As such, NL-201 is designed to promote the desired immunomodulatory anti-tumor effects of IL-2 with an improved safety profile.

Methods: NL201-101 is a Phase 1 first-in-human, open-label, dose-escalation and cohort expansion study consisting of two parts. Part 1 is a monotherapy dose-escalation study in up to 60 adult patients with advanced and/or refractory solid tumors to define the safety profile and the recommended Phase 2 dose (RP2D) and schedule of NL-201. During dose escalation, two different schedules will be evaluated: dosing every 21 days (Schedule A), or on days 1 and 8 of each 21-day cycle (Schedule B). Tumor response will be assessed by Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 and/or RECIST for use in cancer immunotherapy trials (iRECIST). In Part 2, patients with pathologically proven diagnosis of melanoma and renal cell carcinoma (up to N=30/cohort), who have advanced and/or refractory measurable disease and have failed at least one line of treatment, which may include checkpoint inhibitors, will be enrolled. Key exclusion criteria include history of brain cancer or active brain metastases, carcinomatous meningitis, neurologic autoimmune disease; patients previously receiving CAR-T or IL-2-based therapies are not eligible. Recruitment of Part 1 began in April 2021, and the trial is actively enrolling. Clinicaltrials.gov identifier: NCT04659629.

Citation Format: Aung Naing, Margaret Callahan, Brian A. Costello, Brendan Curti, Evan Hall, Aaron Hansen, Georgina V. Long, Anthony M. Joshua, Cynthia Wetmore, Andrew Weickhardt. A first-in-human phase 1 study of NL-201 in patients with relapsed or refractory cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT250.

Abstract 1137: Determination of a recommended Phase 2 dose (RP2D) for SRF388, a first-in-class IL-27-blocking antibody, in patients with advanced solid tumors

SRF388 is a first-in-class, anti-IL-27 antibody developed to enhance immune responses within the tumor microenvironment. Preclinical studies have demonstrated that IL-27 pathway blockade can inhibit tumor growth in mouse models of liver cancer and lung cancer metastases. There is also evidence that IL-27 pathway inhibition is accompanied by activation of the innate and adaptive arms of the immune system. An ongoing Phase I trial has shown good tolerability at all dose levels tested and preliminary monotherapy antitumor activity with SRF388 (NCT04374877). Here, we describe the preclinical and clinical data used to select a RP2D and characterize cytokine and chemokine changes observed in patients after treatment with SRF388. To guide selection of the RP2D, the relationship between maximal effective dose (MaxED), pharmacokinetics (PK), and whole blood inhibition of IL-27-mediated phosphorylation of STAT1 by SRF388 was evaluated in a mouse model of liver cancer. The concentration of SRF388 associated with optimal antitumor activity was ~20-fold above the concentration needed for complete inhibition (&gt; 90%) of whole blood phosphorylated STAT1 (pSTAT1). These PK and activity relationships were also defined in patients during the dose-escalation phase of the trial and integrated with safety and efficacy data to select a monotherapy RP2D. In patients, PK were linear, no dose-limiting toxicities were reported, complete pSTAT1 inhibition was achieved throughout the first cycle at 0.3 mg/kg, and 1 patient experienced a confirmed partial response per RECIST version 1.1 at a dose of 10 mg/kg. In the MaxED mouse model, the area under the concentration versus time curve (AUC) associated with significant antitumor activity was 1720 day*μg/mL. In patients, the corresponding target AUC was achieved clinically at 10 mg/kg after a single dose of SRF388. Changes in the concentration of several serum cytokines and chemokines were observed after SRF388 treatment including an increase in IL-27, a phenomenon described for other anti-cytokine antibodies due to altered clearance of the cytokine-antibody complex. Changes in a subset of other serum cytokines/chemokines correlated with a reduction in target lesion size. Taken together, these data support the selection of a monotherapy RP2D of 10 mg/kg intravenously every 4 weeks for SRF388. These data highlight how complementary strategies utilizing preclinical and clinical biomarker evaluations can be employed to establish a monotherapy RP2D and assess biological activity of a first-in-class anti-cytokine antibody, SRF388, for patients with cancer.

Citation Format: Jonathan A. Hill, Kerry F. White, Matthew Rausch, Jou-Ku Chung, Amita Patnaik, Aung Naing, Daniel Morgensztern, Charlene M. Mantia, Nizar M. Tannir, Lon S. Smith, Beth Bowers, Alex Alika, Lauren C. Harshman, Benjamin H. Lee. Determination of a recommended Phase 2 dose (RP2D) for SRF388, a first-in-class IL-27-blocking antibody, in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1137.

Extracellular vesicle PD-L1 dynamics predict durable response to immune-checkpoint inhibitors and survival in patients with non-small cell lung cancer

BACKGROUND

Immune-checkpoint inhibitors (ICIs) changed the therapeutic landscape of patients with lung cancer. However, only a subset of them derived clinical benefit and evidenced the need to identify reliable predictive biomarkers. Liquid biopsy is the non-invasive and repeatable analysis of biological material in body fluids and a promising tool for cancer biomarkers discovery. In particular, there is growing evidence that extracellular vesicles (EVs) play an important role in tumor progression and in tumor-immune interactions. Thus, we evaluated whether extracellular vesicle PD-L1 expression could be used as a biomarker for prediction of durable treatment response and survival in patients with non-small cell lung cancer (NSCLC) undergoing treatment with ICIs.

METHODS

Dynamic changes in EV PD-L1 were analyzed in plasma samples collected before and at 9 ± 1 weeks during treatment in a retrospective and a prospective independent cohorts of 33 and 39 patients, respectively.

RESULTS

As a result, an increase in EV PD-L1 was observed in non-responders in comparison to responders and was an independent biomarker for shorter progression-free survival and overall survival. To the contrary, tissue PD-L1 expression, the commonly used biomarker, was not predictive neither for durable response nor survival.

CONCLUSION

These findings indicate that EV PD-L1 dynamics could be used to stratify patients with advanced NSCLC who would experience durable benefit from ICIs.

Baseline predictors of hematological toxicity in patients with advanced cancer treated with ATR inhibitors in phase I/II clinical trials

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Background: Ongoing trials are exploring ATR inhibitors (ATRi) in genomically selected contexts. However, myelosuppression, particularly anemia, has limited the therapeutic window of this class of drugs. We sought to discover clinical biomarkers predicting severe hematological toxicity from ATRi. Methods: We retrospectively analyzed clinical parameters and peripheral blood cell indices retrieved from complete blood count (CBC) reports of patients (pts) pre- and during treatment with an oral ATRi on phase I/II trials at our center. Pts received ATRi monotherapy or in combination with a PD1 inhibitor (PD1i) or a PARP inhibitor (ATRi+PARPi) in dose-escalation and expansion cohorts, which included ATRi at potentially toxic doses. Results: 37553 indices from 2209 CBC reports of 141 pts treated with an ATRi from 10/2017 to 1/2022 were analyzed. 132 (93.6%) pts received ATRi +/- PD1i; 9 (6.4%) pts received ATRi+PARPi. The incidences of ≥ grade (G) 3 anemia, neutropenia and thrombocytopenia were 47.5%, 31.9% and 11.4%. 73/141 (51.8%) pts received red cell transfusion. Baseline risk factors predicting ≥G3 anemia on univariate analysis included: lower median (med) hematocrit (Hct) (hazard ratio (HR) (95% confidence interval) = 3.05 (1.82, 5.13) ≤med vs > med; p < 0.0001), hemoglobin (Hb) (HR = 2.74 (1.64,4.57) ≤med vs > med; p = 0.0001), mean corpuscular Hb concentration (HR = 1.85 (1.11,3.10) ≤med vs > med; p = 0.019); and higher median immature reticulocyte fraction (HR = 0.43 (0.25,0.71) ≤med vs > med; p = 0.0012), reticulocyte count (ct) (HR = 0.59 (0.35,0.97) ≤med vs > med; p = 0.037) and red cell distribution width (RDW) (HR = 0.54 (0.33,0.88) ≤med vs > med; p = 0.015). On multivariate analysis, lower median Hct (HR = 3.76 (2.15, 6.6) ≤med vs > med; p < 0.0001), higher immature granulocyte ct (HR = 1.71 (1.30, 2.25) per 1 fold increase; p = 0.0001), higher RDW (HR = 7.83 (1.70, 36.03) per 1 fold increase; p = 0.0082) and higher ATRi starting dose (HR = 1.40 (1.05, 1.86) per 1 fold increase; p = 0.022) significantly predicted ≥G3 anemia risk. Baseline risk factors for ≥G3 neutropenia on univariate analysis included: lower median absolute neutrophil ct (ANC) (HR = 2.26 (1.18, 4.33) ≤med vs > med; p = 0.015) or white blood cell ct (WBC) (HR = 2.73 (1.40, 5.33) ≤med vs > med; p = 0.0032). On multivariate analysis, lower median WBC (HR = 2.85 (1.45, 5.59) ≤med vs > med; p = 0.0024) was associated with higher risk of neutropenia, while ATRi+PARPi increased risk of neutropenia (ANC < 0.75) (HR = 4.15 (1.40, 12.3); p = 0.01) and thrombocytopenia (HR = 3.90 (1.47, 10.4); p = 0.0064). Conclusions: ≥G3 anemia was frequent in pts receiving ATRi. At baseline, lower median Hct and higher RDW predict severe anemia, while lower WBC predicts neutropenia from ATRi. ATRi+PARPi has increased risk of neutropenia and thrombocytopenia vs ATRi +/- PD1i. These indices may inform patient selection and CBC monitoring for future ATRi trials.

Repeat large panel genomic sequencing identifies actionable alterations and characterizes the genomic landscape in patients with metastatic solid tumors

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Background: The implementation of genomic profiling with next generation sequencing has revolutionized the field of precision oncology. Comprehensive genomic testing of tumors to identify actionable genomic alterations is now commonly performed in the care of patients with advanced/metastatic disease. Although the genomic profile of tumors has been shown to evolve with progression and intervening treatments, the role of repeat genomic testing is not well established. We sought to determine the evolution of actionable genomic alterations in patients undergoing repeat genomic testing on the same comprehensive genomic panel. Methods: We retrospectively examined the molecular profiles and medical records of 262 patients with metastatic solid tumors treated in MD Anderson who underwent genomic testing on the same panel (Oncomine, Thermo Fisher) for the detection of somatic mutations in the coding sequence of 143 cancer-related genes, on at least 2 separate occasions. Genomic alterations were reviewed by a central Precision Oncology Decision Support (PODS) team in order to provide annotations at the alteration level on the functional significance. Results: 262 patients underwent repeat genomic testing using the same genomic panel on samples collected at different time points from July 2010 to Dec 2021 across tumor types. Changes in alterations (gain or loss) were identified on repeat testing in most patients (66%) We then specifically assessed changes in alterations that were categorized as actionable if annotated by the PODS team at the time of reporting. A gain or loss of an actionable alteration was detected in 38% (100/262) patients. New actionable alterations were frequently identified (73%; 73/100), while 41% had loss of an actionable alteration (41/100). 14% had both loss and gain of actionable alteration on repeat testing; 58% had new actionable alteration identified alone; 27% had loss of actionable alteration only. Actionable alterations identified on repeat testing included alterations in PI3K/AKT (27%), EGFR (15%), and MAPK (16%). On repeat testing, changes in ³2 actionable alterations were frequently identified in the same test (43%). Conclusions: Repeat large panel genomic testing identifies both gain and loss of actionable alterations in patients with advanced metastatic cancers. Actionable aberrations frequently co-exist with alterations in a variety of other genes, which highlights the complexities of treating patients with metastatic cancer on progression of disease and suggests that tailored combination strategies may be necessary in these patients.

Interim safety and efficacy results from AURELIO-03: A phase 1 dose escalation study of the IL-2/IL-15 receptor βγ superagonist SOT101 as a single agent and in combination with pembrolizumab in patients with advanced solid tumors

2502

Background: SOT101 (previously SO-C101) is a fusion protein of IL-15 and the IL-15 receptor α sushi+ domain. Synergistic effects of SOT101 and an anti-programmed cell death protein 1 antibody have been validated in various tumor mouse models inducing a protective memory response. Methods: In this phase 1 study, safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of increasing doses of SOT101 administered subcutaneously were investigated in patients (pts) with advanced solid tumors as monotherapy (Part A) and in combination with pembrolizumab every 3-week cycle (Part B). Dose escalation followed a standard 3+3 design. Data cut-off was 26 January 2022. Results: Overall, 51 pts were treated: 30 in Part A monotherapy at 0.25 to 15 μg/kg SOT101 and 21 in Part B combination therapy (Tx) at 1.5 to 12 μg/kg SOT101. The median (range) number of previous lines of Tx was 3 (1-9) in Part A and 2 (1-6) in Part B. In Part A, 19 (63.3%) pts had previous check-point inhibitor (CPI) Tx, of whom 9 (30 %) were refractory, 5 (16.7%) relapsed. In Part B, 11 pts (52.4%) had previous CPI Tx, and the outcome was 9 (42.9%) pts relapsed, 1 (4.8%) refractory. The most common treatment-emergent adverse events (TEAEs) were transient, and included pyrexia, chills, lymphopenia, anemia, transaminase elevation and vomiting. Most TEAEs were ≤ Grade 2. No treatment-related death was reported. For both monotherapy and combination Tx, the recommended phase 2 dose of SOT101 was determined to be 12 μg/kg. In Part A, in 13 pts at 6 to 12 μg/kg SOT101, the observed clinical benefit rate was 38%. A partial response (PR) was confirmed in 1 pt with skin squamous cell carcinoma, CPI refractory, PR duration 46 days (d), on treatment 154 d. Four pts (all CPI pretreated) had stable disease (SD), range 33-183 d. Final median duration on treatment was 84 d, range 43-183 d. The median duration of clinical benefit was 190 d. In Part B, the observed clinical benefit rate across all SOT101 doses was 63%. A complete response (CR) was confirmed in 1 pt with mesothelioma, CPI naïve, starting at the first tumor assessment, and the pt is ongoing in cycle 5. Three pts, 2 CPI pretreated, had a PR, range 51-232 d, 2 ongoing with PR, and 1 Tx discontinuation while still on PR. Five pts, 3 CPI pretreated, had SD, range 92-340 d, 2 ongoing with SD. The 3 CPI pretreated pts had SD range 41-340 d, 1 pt ongoing. The preliminary median duration on combination Tx was 113 d, range 7-429 d. The preliminary median duration of clinical benefit was 131 d. Conclusions: SOT101 as monotherapy and in combination with pembrolizumab showed a favorable safety profile. Highly promising efficacy signals with one ongoing CR and several long-lasting PRs were reported in CPI-naïve and CPI pretreated pts, including CPI-resistant tumors. Clinical trial information: NCT04234113.

Phase I/II study of the selective PI3Kβ inhibitor GSK2636771 in combination with pembrolizumab in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) and PTEN loss

5052

Background: PTEN loss activates the PI3K/AKT signaling pathway, contributes to an immunosuppressive tumor microenvironment, resistance to androgen deprivation therapy and poor clinical outcome in pts with mCRPC. Treatment with anti-PD1 antibodies improves survival in many cancers, but efforts to harness its benefit in mCRPC have been unsuccessful. In preclinical PTEN loss models, selective PI3Kβ inhibitor enhanced survival and the frequency of intratumoral T cells. We hypothesized that the combination of PI3Kβ inhibitor and anti-PD-1 antibody is safe and promotes antitumor activity. To test this, we conducted a phase I/II study (NCT01458067) of PI3Kβ inh GSK2636771 and pembrolizumab in pts with solid tumors (including melanoma and mCRPC) with PTEN loss. We report the results from a cohort of pts with mCRPC and PTEN loss. Methods: The phase I primary objective was to determine the safety, tolerability, and recommended phase II dose (RP2D) of GSK2636771 + pembrolizumab using a 3+3 design. Pembrolizumab was given at 200 mg IV Q3W and dose escalation started at 300mg orally daily of GSK2636771 for 21 days cycle. The phase II primary objective was to evaluate the efficacy of the combination using RECIST 1.1. Secondary objectives were to evaluate PK and PD effects in tumor and blood. Tumoral PTEN loss was defined by loss of protein expression by IHC or by presence of an inactivating mutation identified by next-generation sequencing (NGS). Results: A total of 12 pts with mCRPC and PTEN loss were enrolled (2 pts in the dose escalation and 10 pts in the dose expansion cohorts). Median age was 67 years (range 55-80) and pts had a median of 4 lines of prior therapies with 83% of pts receiving prior taxane-based chemotherapy. The RP2D was identified at 200mg PO QD of GSK2636771 + pembrolizumab 200mg IV Q3W. Most treatment-related adverse events were grade (G) 1-2 with the most common being diarrhea (33%) and rash (42%). A total of 4 pts had G3 rash, including 2 pts with G3 immune-related bullous pemphigoid. Dose-limiting toxicities in pts with mCRPC included G3 hypophosphatemia and G3 rash. Treatment was discontinued because of G3 toxicity in 1 pt and 42% of pts required a dose reduction of GSK2636771. Among 11 evaluable pts at 200mg daily of GSK2636771, partial response (PR) was achieved in 2 pts (-56% and -59% as compared to baseline, per RECIST1.1), which was associated with ongoing progression free survival (PFS) > 12 months (24.1 and 13.6 months, respectively) and PSA > 50% reduction as compared to baseline. In addition, a pt with tumor reduction of 18% per RECIST1.1 has remained on treatment for 15.8 months. Conclusions: GSK2636771 plus pembrolizumab had an acceptable safety and tolerability profile. The combination showed promising preliminary antitumor activity and durable responses in a heavily pretreated population of pts with mCRPC. Clinical trial information: NCT01458067.