Clinical Management of Patients with Non-Small Cell Lung Cancer, Brain Metastases, and Actionable Genomic Alterations: A Systematic Literature Review

INTRODUCTION

Nearly 60% of patients with non-small cell lung cancer (NSCLC) present with metastatic disease, and approximately 20% have brain metastases (BrMs) at diagnosis. During the disease course, 25-50% of patients will develop BrMs. Despite available treatments, survival rates for patients with NSCLC and BrMs remain low, and their overall prognosis is poor. Even with newer agents for NSCLC, options for treating BrMs can be limited by their ineffective transport across the blood-brain barrier (BBB) and the unique brain tumor microenvironment. The presence of actionable genomic alterations (AGAs) is a key determinant of optimal treatment selection, which aims to maximize responses and minimize toxicities. The objective of this systematic literature review (SLR) was to understand the current landscape of the clinical management of patients with NSCLC and BrMs, particularly those with AGAs.

METHOD

A Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-compliant SLR was conducted to identify studies in patients with BrMs in NSCLC. Searches used the EMBASE and MEDLINE® databases, and articles published between January 1, 2017 and September 26, 2022 were reviewed.

RESULTS

Overall, 179 studies were included in the SLR. This subset review focused on 80 studies that included patients with NSCLC, BrMs, and AGAs (19 randomized controlled trials [RCTs], two single-arm studies, and 59 observational studies). Sixty-four of the 80 studies reported on epidermal growth factor receptor (EGFR) mutations, 14 on anaplastic lymphoma kinase (ALK) alterations, and two on both alterations. Ninety-five percent of studies evaluated targeted therapy. All RCTs allowed patients with previously treated, asymptomatic, or neurologically stable BrMs; the percentage of asymptomatic BrMs varied across observational studies.

CONCLUSIONS

Although targeted therapies demonstrate systemic benefits for patients with NSCLC, BrMs, and AGAs, there remains a continued need for effective therapies to treat and prevent BrMs in this population. Increased BBB permeability of emerging therapies may improve outcomes for this population.

Patritumab Deruxtecan in Untreated Hormone Receptor-Positive/HER2-Negative Early Breast Cancer: Final Results from Part A of the Window-of-Opportunity SOLTI TOT-HER3 Pre-Operative Study

BACKGROUND

Patritumab deruxtecan (HER3-DXd) is a HER3-directed antibody-drug conjugate composed of a fully human anti-HER3 monoclonal antibody (patritumab) covalently linked to a topoisomerase I inhibitor payload via a stable, tumor-selective, tetrapeptide-based cleavable linker. TOT-HER3 is a window-of-opportunity study designed to assess the biological activity, measured by CelTIL score [ = -.8 × tumor cellularity (in %) + 1.3 × TILs (in %)], and clinical activity of HER3-DXd during short-term (21 days) pre-operative treatment in patients with primary operable HER2-negative early breast cancer.

PATIENTS AND METHODS

Patients with previously untreated hormone receptor (HR)-positive/HER2-negative tumors were allocated to one of four cohorts according to baseline ERBB3 mRNA expression. All patients received one dose of HER3-DXd 6.4 mg/kg. The primary objective was to evaluate change from baseline in CelTIL score.

RESULTS

Seventy-seven patients were evaluated for efficacy. A significant change in CelTIL score was observed, with a median increase from baseline of 3.5 (interquartile range, -3.8 to 12.7; P=.003). Among patients evaluable for clinical response (n=62), an overall response rate of 45% was observed (tumor measurement by caliper), with a trend toward an increase in CelTIL score among responders compared with non-responders (mean difference, +11.9 vs +1.9). Change in CelTIL score was independent of baseline ERBB3 mRNA and HER3 protein levels. Genomic changes occurred, including switching toward a less proliferative tumor phenotype based on PAM50 subtypes, suppression of cell proliferation genes, and induction of genes associated with immunity. Treatment-emergent adverse events were observed in 96% of patients (14% grade ≥3); most common were nausea, fatigue, alopecia, diarrhea, vomiting, abdominal pain, and neutrophil count decrease.

CONCLUSIONS

A single dose of HER3-DXd was associated with clinical response, increased immune infiltration, suppression of proliferation in HR-positive/HER2-negative early breast cancer, and a tolerable safety profile consistent with previously reported results. These findings support further study of HER3-DXd in early breast cancer.

Abstract P5-02-31: Genetic determinants of response to patritumab deruxtecan (HER3-DXd) in hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer: a correlative analysis from SOLTI TOT-HER3 trial

Background: Baseline HER3 protein or ERBB3 mRNA levels do not seem to predict efficacy from HER3-DXd in early-stage and advanced HR+/HER2- breast cancer (Prat et al. ESMO Breast 2022; Krop et al. ASCO 2022). Here, we evaluated potential baseline pre-treatment genetic determinants of efficacy to HER3-DXd. Methods: SOLTI TOT-HER3 (NCT04610528) is a window of opportunity, multicenter, pre-operative trial which enrolled, in part A, 77 evaluable patients with untreated HR+/HER2- operable (≥1 cm) breast cancer. Patients received a single dose of HER3-DXd (6.4 mg/kg). The primary objective was to evaluate the CelTIL score variation between pre- and post-treatment (day 21) samples. CelTIL combines % of tumor cellularity and % of tumor-infiltrating lymphocytes into a single score. DNA and RNA were purified from pre-treatment baseline FFPE tumor samples. Gene expression was evaluated using a custom 67-gene panel on the nCounter. NGS-based DNA-seq was performed using the VHIO-300 panel, which estimates tumor mutational burden (TMB), identifies copy-number aberrations (CNAs) across the entire genome and calls mutational status of >300 genes. From CNA data, 150 previously defined DNA-based signatures (Xia et al. Nat Comm 2019) trained to capture RNA- and protein-based phenotypes such as the PAM50-related biology were evaluated. Associations of each variable with efficacy (i.e., CelTIL relative changes, and tumor cellularity relative changes) were adjusted for multiple-testing (false discovery rate [FDR] < 5%). The area under the ROC Curve (AUC) was used to estimate the discrimination performance of each variable. Results: RNA and DNA data were obtained from 45 (58%) patients. Baseline characteristics in this subset of patients were generally similar to the original TOT-HER3 population. Among 228 variables (single mutation status, single gene expression, PAM50 signatures, TMB, and DNA CNA-based signatures), 139 (61%) were found significantly associated (FDR< 5%) with CelTIL changes at day 21. Among them, TP53 mutations (n=7) were found associated with higher CelTIL response compared to TP53 wild type (71% [95% CI=-5.4-17.8] vs. 24% [95% CI=15.9-55.4], FDR=2.1%). In addition, RNA-based genes tracking Basal-related biology (e.g., CCNE1, AUC=0.71) or immune expression (e.g., PDCD1, AUC=0.73, or CD68, AUC=0.62), together with RNA/DNA-based signatures tracking proliferation and/or basal-related biology (e.g., retinoblastoma loss-of-heterozygozity [RB-LOH], AUC=0.76), were associated with high CelTIL response. Conversely, RNA/DNA-based signatures tracking endocrine sensitivity/Luminal A-related biology (e.g., Scorr_IE_Correlation, AUC=0.76) were associated with low/lack of CelTIL response. PIK3CA somatic mutations (n=14, 31% of cases), and TMB (range 2.2-12.7) were not found associated with CelTIL response. Similar overall results were obtained when relative changes in tumor cellularity (instead of CelTIL) was evaluated as the efficacy endpoint. Conclusions: TP53 mutations, immune-related genes, and DNA/RNA-based phenotypic signatures tracking Basal- or Luminal A-related biology such as the DNA-based RB-LOH score or the endocrine sensitivity score (Scorr_IE_Correlation) are associated with CelTIL changes in response to HER3-DXd in HR+/HER2- breast cancer. Further RNA- and DNA-based analyses will be evaluated.

Citation Format: Fara Brasó-Maristany, Claudette Falato, Olga Martínez-Sáez, Juan Miguel Cejalvo, Mireia Margelí, Pablo Tolosa, Francisco Javier Salvador Bofill, Josefina Cruz, Blanca González-Farré, Esther Sanfeliu, Míriam Arumí, Guillermo Villacampa, Eva Ciruelos, Martín Espinosa-Bravo, Yann Izarzuzaga, Patricia Galván, Judit Matito, Sonia Pernas, Anu Santhanagopal, Stephen Esker, Parul Patel, Pang-Dian Fan, Juan Manuel Ferrero-Cafiero, Ana Vivancos, Tomás Pascual, Aleix Prat, Mafalda Oliveira. Genetic determinants of response to patritumab deruxtecan (HER3-DXd) in hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer: a correlative analysis from SOLTI TOT-HER3 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-31.

Pharmacokinetic Considerations in Determining the Terminal Elimination Half-Lives of Bisphosphonates

BACKGROUND AND OBJECTIVE

Bisphosphonates are commonly used to treat and prevent osteoporosis. These compounds have unusual pharmacokinetic characteristics because they bind strongly to bone, and a portion becomes buried under newly formed bone. Once incorporated into bone tissue, the subsequent release during bone remodeling is probably the rate-limiting step in the terminal elimination of bisphosphonates. Because of this unique property of bisphosphonates, pharmacokinetic studies with insufficient lengths of follow-up might entirely miss the true terminal elimination phase. A terminal half-life (t((1/2)gamma)) of approximately 11 years, similar to that of calcium and other minerals in bone, was reported from an 18-month study of alendronic acid in postmenopausal women with osteoporosis. We are not aware of any other published reports in which the elimination of a bisphosphonate has been followed for more than a few weeks post-dose. The purpose of the present study was to reanalyse the alendronic acid data to examine the effect of truncating the length of follow-up on the calculated t((1/2)gamma).

PATIENTS AND METHODS

Twenty-one postmenopausal women with osteoporosis (mean age 66 years) received intravenous alendronic acid 30mg over 4 consecutive days (7.5 mg/day), and urinary excretion of alendronic acid was monitored over the following 18-24 months. Terminal elimination half-life was originally calculated by log-linear regression of the percentage retained versus time curve between days 240 and 540 and substituting the slope of the regression line into the equation, t((1/2)gamma) = -log 2/slope. These data were reanalysed based on the period up to 30 days.

RESULTS

Data were sufficient for analysis of pharmacokinetics in 11 patients. A mean t((1/2)gamma) of approximately 11 years was reported previously, based on analysis of data between days 240 and 540. Recalculating the 'terminal' half-life of alendronic acid using only data from the first 30 days resulted in an 'observed' half-life of only 11 days.

CONCLUSION

This analysis illustrates the importance of sufficient length of follow-up to accurately characterise the true terminal elimination half-life of bisphosphonates. The relatively short (expressed in units of days rather than years) terminal elimination half-lives reported for some bisphosphonates based on only 30 days of follow-up or less are likely to substantially underestimate the true terminal elimination half-lives.

Epidermal growth factor stimulates proton efflux from chondrocytic cells

Proton efflux from chondrocytes alters the extracellular pH and ionic composition of cartilage, and influences the synthesis and degradation of extracellular matrix. Epidermal growth factor (EGF) promotes chondrocyte proliferation during skeletal development and accumulates in the synovial fluid in rheumatoid arthritis. The purpose of this study was to investigate the effect of EGF on proton efflux from chondrocytes. When monitored using a Cytosensor microphysiometer, EGF was found to rapidly activate proton efflux from CFK2 chondrocytic cells and rat articular chondrocytes. The actions of EGF were concentration-dependent with half-maximal effects at 0.3-0.7 ng/ml. Partial desensitization and time-dependent recovery of the response were observed following repeated exposures to EGF. EGF-induced proton efflux was dependent on extracellular glucose, and inhibitors of Na(+)/H(+) exchange (NHE) markedly attenuated the initial increase in proton efflux. The response was diminished by inhibitors of phosphatidylinositol 3-kinase and phospholipase C, but not by inhibitors of MEK (MAPK/ERK kinase) or protein kinase A or C. Thus, EGF-induced proton efflux involves glucose metabolism and NHE, and is regulated by a discrete subset of EGF-activated signaling pathways. In vivo, proton efflux induced by EGF may lead to an acidic environment, enhancing turnover of cartilage matrix during development and in rheumatoid arthritis.

Calcitonin (CT) rapidly increases NA(+)/H(+) exchange and metabolic acid production: effects mediated selectively by the C1A CT receptor isoform

Two isoforms of the calcitonin receptor are expressed in rabbit: the common C1a isoform and the calcitonin receptor Delta e13 isoform, which has a deletion in the seventh transmembrane domain. Using microphysiometry, we investigated the effects of calcitonin on proton efflux from HEK293 cells stably transfected with C1a, calcitonin receptor Delta e13, or empty vector. In C1a-expressing cells only, calcitonin rapidly induced a biphasic elevation in proton efflux consisting of an initial transient and a sustained plateau, accompanied by an increase in lactate efflux. Inhibitors of Na(+)/H(+) exchange abolished only the initial transient, whereas removal of extracellular glucose abolished only the sustained plateau. These data suggest that activation of Na(+)/H(+) exchange mediates the initial transient, whereas increased glucose metabolism underlies the sustained plateau. Because both receptor isoforms activate adenylyl cyclase, the lack of effect of calcitonin on proton efflux from calcitonin receptor Delta e13-expressing cells argued against involvement of cAMP in activating proton efflux. Similarly, studies involving elevation or buffering of cytosolic free Ca(2+) concentration argued against involvement of Ca(2+). Activation of PKC mimicked the plateau phase of calcitonin-induced proton efflux from C1a cells, whereas inhibition or depletion of PKC suppressed it. Activation of proton transport and production are novel cellular responses to calcitonin, mediated selectively by the C1a receptor isoform via a mechanism involving PKC.

Insulin-like growth factor I rapidly enhances acid efflux from osteoblastic cells

Insulin-like growth factor I (IGF-I) is thought to stimulate bone resorption indirectly through a primary effect on osteoblasts, which in turn activate osteoclasts by as-yet-unidentified mechanisms. Small decreases in extracellular pH (pHo) dramatically increase the resorptive activity of osteoclasts. Our purpose was to characterize the effect of IGF-I on acid production by osteoblastic cells. When confluent, UMR-106 osteoblast-like cells and rat calvarial cells acidified the compartment beneath them. Superfusion with IGF-I caused a further decrease in pHo. To investigate the mechanism, we monitored acid efflux from subconfluent cultures. IGF-I rapidly increased net efflux of H+ equivalents in a concentration-dependent manner. IGF-II (10 nM) evoked a smaller response than IGF-I (10 nM). The response to IGF-I was partially dependent on extracellular Na+, but not glucose, and exhibited little if any desensitization. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, abolished the response to IGF-I but not to parathyroid hormone. Thus IGF-I enhances acid efflux from osteoblastic cells, via a signaling pathway dependent on activation of phosphatidylinositol 3-kinase. In vivo, acidification of the compartment between the osteogenic cell layer and the bone matrix may affect diverse processes, including mineralization and osteoclastic bone resorption.

The calcitonin receptor stimulates Shc tyrosine phosphorylation and Erk1/2 activation. Involvement of Gi, protein kinase C, and calcium

While it is well established that adenylyl cyclase and phospholipase C-beta are two proximal signal effectors for the calcitonin receptor, the more distal signaling pathways are less well characterized. G protein-coupled receptors can activate Erk1/2 by Gs-, Gi-, or Gq-dependent signaling pathways, depending on the specific receptor and cell type examined. Since the calcitonin receptor can couple to all three of these G proteins, the ability of calcitonin to activate Erk1/2 was investigated. Calcitonin induced time- and concentration-dependent increases in Shc tyrosine phosphorylation, Shc-Grb2 association and Erk1/2 phosphorylation and activation in a HEK 293 cell line that stably expresses the rabbit calcitonin receptor C1a isoform. Pertussis toxin, which inactivates Gi, and calphostin C, a protein kinase C inhibitor, each partially inhibited calcitonin-induced Shc tyrosine phosphorylation, Shc-Grb2 association, and Erk1/2 phosphorylation. In contrast, neither forskolin nor H89, a protein kinase A inhibitor, had a significant effect on basal or calcitonin-stimulated Erk1/2 phosphorylation. Our results suggest that the calcitonin receptor induces Shc phosphorylation and Erk1/2 activation in HEK293 cells by parallel Gi- and PKC-dependent mechanisms. The calcitonin-induced elevation of cytosolic free Ca2+ was required for Erk1/2 phosphorylation, since preventing any change in cytosolic free Ca2+ by chelating both cytosolic and extracellular Ca2+ abolished the response. However, the change in Ca2+ that is induced by calcitonin is not sufficient to account for the calcitonin-induced Erk1/2 phosphorylation, since treatment with 100 nM ionomycin or 10 microM thapsigargin, each of which induced elevations of Ca2+ comparable to those induced by calcitonin, induced significantly less Erk1/2 phosphorylation than that induced by calcitonin. Erk1/2 may have important roles as downstream effectors mediating cellular responses to calcitonin stimulation.