RET Rearrangement as a Predictor of Unresponsiveness to Immunotherapy in Non-Small Cell Lung Cancer: Report of Two Cases with Review of the Literature

Response to immune checkpoint inhibitor combination therapy in metastatic RET-mutated lung cancer from real-world retrospective data

BACKGROUND

The impact of immune checkpoint inhibitors (ICIs) based treatments on non-small cell lung cancers (NSCLCs) with RET fusions remains poorly understood.

METHODS

We screened patients with RET fusions at the First Affiliated Hospital of Zhengzhou University and included those who were treated with ICIs based regimens for further analysis. We evaluated clinical indicators including objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS).

RESULTS

A total of 232 patients with RET fusions were included in the study. Of these, 129 patients had their programmed death-ligand 1 (PDL1) expression levels tested, with 22 patients (17.8%) having a PDL1 level greater than or equal to 50%. Additionally, tumor mutational burden (TMB) status was evaluated in 35 patients, with the majority (30/35, 85.8%) having a TMB of less than 10 mutations per megabase. Out of the 38 patients treated with ICI based regimens, the median PFS was 5 months (95% confidence interval [CI]: 2.4-7.6 months) and the median OS was 19 months (95% CI: 9.7-28.3 months) at the time of data analysis. Stratification based on treatment lines did not show any significant differences in OS (18 vs. 19 months, p = 0.63) and PFS (6 vs. 5 months, p = 0.86). The ORR for patients treated with ICIs was 26.3%. Furthermore, no significant differences were found for PFS (p = 0.27) and OS (p = 0.75) between patients with positive and negative PDL1 expression. Additionally, there was no significant difference in PD-L1 levels (p = 0.10) between patients who achieved objective response and those who did not.

CONCLUSIONS

Patients with RET fusion positive NSCLCs may not benefit from ICI based regimens and therefore should not be treated with ICIs in clinical practice.

Clinical evidence and adverse event management update of patients with RET- rearranged advanced non-small-cell lung cancer (NSCLC) treated with pralsetinib

Current non-small cell lung cancer (NSCLC) management relies on genome-driven precision oncology thus shifting treatment paradigm towards biomarker-guided tumor-agnostic approaches. Recently, rearranged during transfection (RET) has been endorsed as tissue-agnostic target with sensitivity to RET inhibition. There are currently two selective RET tyrosine kinase inhibitors, pralsetinib and selpercatinib. The recent introduction of pralsetinib in the treatment algorithm of RET-rearranged tumor along with the mounting clinical evidence of pralsetinib durable activity from both randomized and observational studies holds the potential to disclose new avenues in the management of RET fusion positive NSCLC patients. Our narrative review aims to discuss the available clinical evidence on pralsetinib efficacy, particularly on brain metastases, and tolerability profile. In addition, our work explores the relevance of detecting RET fusions upfront in the disease history of patients with NSCLC.

Selpercatinib in RET-fusion positive metastatic non-small cell lung cancer: achievements and gray areas

INTRODUCTION

Selpercatinib is a RET selective tyrosine kinase inhibitor with nanomolar potency against diverse RET alterations, including fusions, activating point mutations, and acquired resistance mutations. Rearranged during transfection (RET) gene is a validated target in non-small-cell lung cancer (NSCLC). Selpercatinib is currently approved for adult patients with metastatic RET fusion-positive NSCLC.

AREAS COVERED

This review summarizes the efficacy and safety data of selpercatinib in the treatment landscape of RET fusion-positive NSCLC.

EXPERT OPINION

Globally considered, selpercatinib is an optimal treatment choice, in terms of both (systemic and intracranial) efficacy and safety, in patients affected by advanced NSCLC harboring RET fusions as a driver mechanism. Future challenges include the identification of the most appropriate placement for selpercatinib in the treatment algorithm of RET fusion-positive NSCLC (including early stages), the clarification of resistance mechanisms, as well as of its role in EGFR-mutant NSCLC undergoing progression during osimertinib driven by RET alterations.

Hypersensitivity Reactions to Selpercatinib Treatment With or Without Prior Immune Checkpoint Inhibitor Therapy in Patients With NSCLC in LIBRETTO-001

INTRODUCTION

Immune checkpoint inhibitor (ICI) therapy has been found to increase the risk/severity of immune-mediated adverse events with subsequent kinase inhibitor treatment in oncogenically driven cancers. We explored the risk for hypersensitivity with selpercatinib, a first-in-class highly selective and potent, central nervous system-active RET inhibitor, in prior ICI-treated patients with RET fusion-positive NSCLC compared with their ICI-naive counterparts.

METHODS

Data from patients enrolled by December 16, 2019, in the ongoing phase 1/2 LIBRETTO-001 (NCT03157128) trial were analyzed for hypersensitivity reactions reported using preferred terms of hypersensitivity/drug hypersensitivity and defined as a constellation of symptoms/findings characterized by maculopapular rash, often preceded by fever with arthralgias/myalgias, followed by greater than or equal to 1 of the following signs/symptoms: thrombocytopenia, increased aspartate aminotransferase or alanine aminotransferase, hypotension, tachycardia, or increased creatinine.

RESULTS

Of 329 patients, 22 (7%) who experienced a grade 1 to 3 hypersensitivity reaction that met the defined constellation of events were attributed to selpercatinib by investigators, and more often in prior ICI-treated (n = 17, 77%) than ICI-naive (n = 5, 23%) patients. There were 19 patients with selpercatinib-related hypersensitivity who resumed selpercatinib post-hypersensitivity with dose modification/supportive care. Furthermore, 17 patients, of whom 14 received prior ICI therapy, were still on treatment at twice daily doses of 40 mg (n = 5), 80 mg (n = 4), 120 mg (n = 4), and 160 mg (n = 4).

CONCLUSIONS

Rates of selpercatinib-related hypersensitivity were low overall and, as with other kinase inhibitors, occurred predominantly in prior ICI-treated patients. Hypersensitivity to selpercatinib can be managed with supportive care measures regardless of prior ICI status and is reversible.

Non-Small-Cell Lung Cancer Patients with Coexistence of High PD-L1 Expression and RET Fusion-Which Path Should We Follow? Case Reports and Literature Review

Pembrolizumab is widely used in first-line treatment in patients with advanced non-small-cell lung cancer (NSCLC) with high PD-L1 expression. The activity of pembrolizumab in NSCLC patients with rare molecular alterations is poorly characterised. RET gene rearrangements are identified in 1−2% of lung cancer patients. Here, we present two cases of RET-rearranged NSCLC patients with high PD-L1 expression (>50%), treated with pembrolizumab within routine clinical practice. Pembrolizumab was ineffective in both cases—single-agent immunotherapy seems to be of limited value in this group of patients. Selective RET-inhibitors, if available, are the optimal treatment for patients with RET fusion nowadays. The best sequence of the therapy is still not defined.

Integrin signaling gene alterations and outcomes of cancer patients receiving immune checkpoint inhibitors

BACKGROUND

Immune evasion is a hallmark of cancer and is associated with resistance to PD-1/PD-L1 and CTLA-4 inhibitors. Several interactions between tumor and immune cells within the tumor microenvironment are effected through integrin signaling; however the latter has been underrecognized as a pathway that could have an impact on oncological outcomes after treatment with immune checkpoint inhibitors (ICIs). This study aimed to assess the clinical relevance of genomic alterations in the integrin signaling pathway in ICI-treated patients with advanced cancers.

METHODS

Next generation sequencing (NGS) data from tumor samples of patients with advanced cancers treated with ICIs (anti-PD-1/PD-L1, anti-CTLA4 or both) were queried from four independent publicly available cohorts for mutations and structural variations in 72 integrin signaling pathway genes (Gene Set: GOBP_CELL_ADHESION_MEDIATED_BY_INTEGRIN). The Kaplan Meier method was used to assess the association between mutated and unmutated genes with overall (OS) and progression-free survival (PFS). All results were reported at the 0.05 significance level.

RESULTS

The largest cohort included 1662 patients (discovery set) and comprised 350 non-small cell lung cancer (NSCLC), 321 melanoma, 214 bladder, 151 renal cell carcinoma (RCC), 138 head neck (HN), 126 esophageal/gastric (EG), 117 glioma, 110 colorectal (CRC), 90 cancer of unknown primary (CUP), and 45 breast cancer patients. ICI treatments included PD-1 or PD-L1 inhibitors (n=1256), anti-CTLA4 inhibitors (n=146) or both (n=260). 170 patients (10% of the entire cohort) harbored mutations in PIK3CG (6%), RET (3%), SYK (1.4%), LYN (1.4%), PTPN11 (1.3%), and CRKL (0.1%) genes. Presence of these mutations was more frequent in melanoma (18%), followed by CRC (14.5%), CUP (11%), and NSCLC (11%). Patients with mutated tumors experienced a significantly longer median OS (41 months) compared to those without alterations (16 months, log-rank P<0.001). The favorable prognostic value of PIK3CG, RET, SYK, LYN, PTPN11, and CRKL alterations was confirmed in three melanoma cohorts (validation set, n=212, P=0.024). Assessment of mutation status of these genes in a fourth cohort of NSCLC patients (n=75) revealed a predictive significance as well, with regard to PFS after treatment with ipilimumab and nivolumab combination (P=0.048).

CONCLUSION

Mutations and/or structural variations in integrin signaling genes may have prognostic and predictive value in patients with metastatic malignancies who receive ICIs. Although confirmation in larger studies with concurrent investigation of underlying immunologic mechanisms is needed, these findings pose therapeutic implications for co-targeted approaches to overcome immune evasion and resistance.

Hallmarks of RET and Co-occuring Genomic Alterations in RET-aberrant Cancers

Activating receptor-tyrosine kinase rearranged during transfection (RET) mutations and fusions are potent drivers of oncogenesis. The recent FDA approvals of highly potent and selective RET inhibitors, selpercatinib and pralsetinib, has altered the therapeutic management of RET aberrant tumors. There is ample evidence of the role of RET signaling in certain cancers. RET aberrations as fusions or mutations occur in multiple cancers, however, there is considerable phenotypic diversity. There is emerging data on the lack of responsiveness of immunotherapy in RET-altered cancers. Herein, we review the registrational data from the selective RET-inhibitor trials, and comprehensively explore RET alterations in pan-cancer adult malignancies and their co-alterations. These co-occuring alterations may define the future of RET inhibition from specific selective targeting to customized combination therapies as data are rapidly emerging on both on-target and off-target acquired resistance mechanisms. Fascinatingly, oncogenic RET fusions have been reported to mediate resistance to EGFR inhibition and KRAS^G12C inhibition.

Frontline pembrolizumab for the treatment of RET-rearranged non-small cell lung cancer: A case report

RET-rearrangement occurs in 1 to 2% of patients with non-small cell lung cancer (NSCLC), typically among non-smokers, and it is associated with an increased incidence of brain metastasis. While selpercatinib and pralsetinib are active for RET-rearranged NSCLC, the optimal standard frontline regimen for this clinical setting remains undefined. Here, we report on a patient with RET-rearranged NSCLC who received frontline pembrolizumab and achieved a complete tumor response lasting for 29 months and ongoing. Single-agent ICI can be an effective frontline treatment for RET-rearranged NSCLC.

Selpercatinib in RET fusion-positive non-small-cell lung cancer (SIREN): a retrospective analysis of patients treated through an access program

INTRODUCTION

Rearranged during transfection (RET) gene fusions are rare genetic drivers in non-small cell lung cancer (NSCLC). Selective RET-inhibitors such as selpercatinib have shown therapeutic activity in early clinical trials; however, their efficacy in the real-world setting is unknown.

METHODS

A retrospective efficacy and safety analysis was performed on data from RET fusion-positive NSCLC patients who participated in a selpercatinib access program (named patient protocol) between August 2019 and January 2021.

RESULTS

Data from 50 patients with RET fusion-positive advanced NSCLC treated with selpercatinib at 27 centers in 12 countries was analyzed. Most patients were Non-Asian (90%), female (60%), never-smokers (74%), with a median age of 65 years (range, 38-89). 32% of the patients had known brain metastasis at the time of selpercatinib treatment. Overall, 13 patients were treatment-naïve, while 37 were pretreated with a median of three lines of therapy (range, 1-8). The objective response rate (ORR) was 68% [95% confidence interval (CI), 53-81] in the overall population. The disease control rate was 92%. The median progression-free survival was 15.6 months (95% CI, 8.8-22.4) after a median follow-up of 9 months. In patients with measurable brain metastases (n = 8) intracranial ORR reached 100%. In total, 88% of patients experienced treatment-related adverse events (TRAEs), a large majority of them being grade 1 or 2. The most common grade ⩾ 3 TRAEs were increased liver enzyme levels (in 10% of patients), prolonged QTc time (4%), abdominal pain (4%), hypertension (4%), and fatigue/asthenia (4%). None of patients discontinued selpercatinib treatment for safety reasons. No new safety concerns were observed, nor where there any treatment-related death.

CONCLUSIONS

In this real-world setting, the selective RET-inhibitor selpercatinib demonstrated durable systemic and intracranial antitumor activity in RET fusion-positive NSCLC and was well tolerated.

What Is New in Biomarker Testing at Diagnosis of Advanced Non-Squamous Non-Small Cell Lung Carcinoma? Implications for Cytology and Liquid Biopsy

The discovery and clinical validation of biomarkers predictive of the response of non-squamous non-small-cell lung carcinomas (NS-NSCLC) to therapeutic strategies continue to provide new data. The evaluation of novel treatments is based on molecular analyses aimed at determining their efficacy. These tests are increasing in number, but the tissue specimens are smaller and smaller and/or can have few tumor cells. Indeed, in addition to tissue samples, complementary cytological and/or blood samples can also give access to these biomarkers. To date, it is recommended and necessary to look for the status of five genomic molecular biomarkers (EGFR, ALK, ROS1, BRAFV600, NTRK) and of a protein biomarker (PD-L1). However, the short- and more or less long-term emergence of new targeted treatments of genomic alterations on RET and MET, but also on others’ genomic alteration, notably on KRAS, HER2, NRG1, SMARCA4, and NUT, have made cellular and blood samples essential for molecular testing. The aim of this review is to present the interest in using cytological and/or liquid biopsies as complementary biological material, or as an alternative to tissue specimens, for detection at diagnosis of new predictive biomarkers of NS-NSCLC.

A case of dramatic reduction in cancer-associated thrombus following initiation of pembrolizumab in patient with a poor performance status and PD-L1+ lung adenocarcinoma harboring CCDC6-RET fusion gene and NF1/TP53 mutations

OBJECTIVES

Pembrolizumab is a standard treatment for non-small cell lung cancer (NSCLC) with high-PD-L1 expression; however, its effect is dismal in patients with poor physical condition. Additionally, the effect of immunotherapy is generally limited in NSCLC harboring driver mutations such asEGFR, ALK, or RET gene aberrations.

RESULTS

We report the beneficial effect of pembrolizumab in a patient with poor performance status and PD-L1+ lung adenocarcinoma with theCCDC6-RET fusion gene and co-occurring NF1/TP53 mutations, complicated by multiple cancer-associated thrombi and respiratory failure.

CONCLUSIONS

Further studies are warranted to establish the role of co-occurring NF1/TP53 mutations as a positive predictive biomarker for pembrolizumab in NSCLC harboring RET fusion genes.

Is there any place for immune-checkpoint inhibitors in the treatment algorithm of fusion-driven non-small cell lung cancer?-a literature review

The advent of immune-checkpoint inhibitors (ICIs) targeting the programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) axis, produced a paradigm change of the treatment algorithm for metastatic, non-oncogene addicted, non-small cell lung cancer (NSCLC). However, the majority of patients with oncogene-addicted disease have been excluded from the “immunotherapy revolution”, thus the clinical efficacy of these agents in this subset of patients remains largely unknown. Although pre-clinical evidence provided a good rationale to pursue the investigation of ICI treatment in specific subgroups of oncogene-addicted NSCLC, current available evidence suggested that tumors harboring molecular alterations likely do not represent the best candidate to single agent ICI therapy. Furthermore, the prospect of further improving overall survival (OS) with the combination of tyrosine kinase inhibitors (TKIs) and ICIs led to unexpected poor results and safety issues in recent phase I trials exploring different therapeutic associations. Conversely, the combination of immunotherapy and chemotherapy is emerging as a potential effective strategy in specific subsets of NSCLC patients harboring oncogenic drivers. In this review we particularly focus on the subgroup of patients whose disease harbor oncogenic rearrangements, summarizing current evidence from preclinical and clinical studies and discussing their practical implications, in order to define the potential role of ICIs in the clinical management of fusion-driven NSCLC.