Efficacy of first-line treatment options beyond RET-TKIs in advanced RET-rearranged non-small cell lung cancer: A multi-center real-world study

BACKGROUND

Although RET-tyrosine kinase inhibitors (RET-TKIs) are the preferred first-line therapy for advanced RET-arranged NSCLC, most patients cannot afford them. In this population, bevacizumab, immunotherapy, and chemotherapy are the most commonly used regimens. However, the optimal scheme beyond RET-TKIs has not been defined in the first-line setting.

METHODS

This retrospective study included 86 stage IV NSCLC patients harboring RET rearrangement from six cancer centers between May 2017 and October 2022. RET-TKIs, chemotherapy, or one of the combination therapies (including immune checkpoint inhibitor (ICI) combined with chemotherapy (I + C), bevacizumab combined with chemotherapy (B + C), ICI and bevacizumab combined with chemotherapy (I + B + C)), were used as the first-line therapeutics. The clinical outcomes and safety were evaluated.

RESULTS

Fourteen of the 86 patients received RET-TKIs, 57 received combination therapies, and 15 received chemotherapy alone. Their medium PFS (mPFS) were 16.92 months (95% CI: 5.9-27.9 months), 8.7 months (95% CI: 6.5-11.0 months), and 5.55 months (95% CI: 2.4-8.7 months) respectively. Among all the combination schemes, B + C (p = 0.007) or I + B + C (p = 0.025) gave beneficial PFS compared with chemotherapy, while I + C treatment (p = 0.169) generated comparable PFS with chemotherapy. In addition, I + B + C treatment had a numerically longer mPFS (12.21 months) compared with B + C (8.74 months) or I + C (7.89 months) schemes. In terms of safety, I + B + C treatment led to the highest frequency of hematological toxicity (50%) and vomiting (75%), but no ≥G3 adverse effect was observed.

CONCLUSIONS

I + B + C might be a preferred option beyond RET-TKIs in the first-line therapy of RET-arranged NSCLC. Combination with Bevacizumab rather than with ICIs offered favorable survival compared with chemotherapy alone.

Pathological characteristics and tumour immune microenvironment of lung malignancies with RET rearrangement

BACKGROUND

For patients with lung malignancies with RET rearrangement, the efficacy of immune checkpoint inhibitors is limited. The characteristics of the tumour immune microenvironment (TIME) and molecular pathological features of these patients have not been well elucidated. We aimed to investigate their clinical outcomes and explore characteristics of TIME, using multiplex immunohistochemistry technology (mIHC).

PATIENTS AND METHODS

The pathology and TIME characteristics of 29 patients with lung malignancies with RET rearrangement were retrospectively analysed, and their relationships with clinical efficacy and prognosis were investigated. Gene detection relied on high-throughput sequencing, and TIME detection was based on mIHC.

RESULTS

Of 29 patients, 25(86%) had adenocarcinoma, and the acinar type accounted for the greatest percentage of patients, followed by the solid type, regardless of whether the disease was early or locally advanced and metastatic. In addition, we report a novel KIF5B-RET(k24:R8) rearrangement in pulmonary sarcoma. The density of CD8+ T cells in tumour stroma in early-stage patients was significantly higher than that in locally advanced and metastatic patients (P = 0.014). The proportion of M2 macrophages in tumour stroma was significantly higher than that in tumour parenchyma (P = 0.046). Although the difference was not statistically significant (P = 0.098), patients positive for M2 macrophage infiltration into the tumour parenchyma (≥5%) may have a better prognosis. Seven patients received immunotherapy and disease control rate was 85.7%.

CONCLUSIONS

A novel KIF5B-RET rearrangement variant in pulmonary sarcoma shows similar TIME characteristics to lung cancer. amongst patients with lung malignancies with RET rearrangement, patients with M2 macrophage infiltration into the tumour parenchyma may have a better prognosis, but further studies with larger cohorts are needed.

Pralsetinib in RET fusion-positive non-small-cell lung cancer: A real-world data (RWD) analysis from the Italian expanded access program (EAP)

OBJECTIVES

The selective RET-inhibitor pralsetinib has shown therapeutic activity in early clinical trials in patients with non-small cell lung cancer (NSCLC) harboring rearranged during transfection (RET) gene fusions. To date, the real-world efficacy of pralsetinib in this population is unknown.

MATERIALS AND METHODS

A retrospective efficacy and safety analysis was performed on data from patients with RET-fusion positive NSCLC enrolled in the pralsetinib Italian expanded access program between July 2019 and October 2021.

RESULTS

Overall, 62 patients with RET-fusion positive NSCLC received pralsetinib at 20 Italian centers. Next-generation sequencing was used to detect RET alterations in 44 patients (73 %). The most frequent gene fusion partner was KIF5B (75 % of 45 evaluable). Median age was 62 years (range, 36-90), most patients were female (57 %) and never smokers (53 %). Brain metastases were known in 18 patients (29.5 %) at the time of pralsetinib treatment. 13 patients were treatment naïve (unfit for chemotherapy), 48 were pretreated (median number of previous lines: 1, range, 1-4). The objective response rate (ORR) was 66 % [95 % confidence interval (CI), 53-81] in the evaluable population (n = 59). The disease control rate (DCR) was 79 %. After a median follow-up of 10.1 months, the median progression free survival was 8.9 months (95 %CI, 4.7-NA). In patients with measurable brain metastases (n = 6) intracranial ORR was 83 %, intracranial DCR was 100 %. Overall, 83.6 % of patients experienced any-grade treatment-related adverse events (TRAEs), 39 % grade 3 or greater (G ≥ 3). The most common G ≥ 3 TRAEs were neutropenia (9.8 %), dry mouth/oral mucositis (8.2 %), and thrombocytopenia (6.6 %). Seven patients (12 %) discontinued pralsetinib due to TRAEs, twenty-six had at least one dose level modification due to TRAEs. Two treatment-related deaths were observed (1 sepsis, 1 typhlitis).

CONCLUSIONS

In the real-world setting, pralsetinib confirmed durable systemic activity and intracranial response in RET-fusion positive NSCLC. Toxicity profile was consistent with previous reports.

RET fusions as primary oncogenic drivers and secondary acquired resistance to EGFR tyrosine kinase inhibitors in patients with non-small-cell lung cancer

BACKGROUND

RET fusions are rare oncogenic drivers in non-small cell lung cancer (NSCLC). While activating RET rearrangements are found in NSCLC patients harboring epidermal growth factor receptor (EGFR) genetic alterations at resistance to EGFR inhibitors, the extent to which co-occurring genomic alterations exist and how they might affect prognosis or therapy response is poorly understood.

METHODS

Targeted next-generation sequencing (NGS) was used to assess 380 baseline patients with primary RET fusions and 71 EGFR-mutated NSCLC patients who acquired RET fusions after developing resistance to EGFR-tyrosine kinase inhibitors (EGFR-TKIs).

RESULTS

Primary RET fusions were more likely associated with females and younger age, with KIF5B being the predominant fusion partner. In baseline patients, both SMAD4 (5.3% vs. 0.0%, P = 0.044) and MYC copy-number gain variants (6.9% vs. 0.0%, P = 0.009) were more frequently co-mutated with KIF5B-RET than CCDC6-RET. By contrast, CDKN2A (11.3% vs. 2.4%, P = 0.003) mutations were significantly enriched in CCDC6-RET-rearranged baseline patients. A significant increase in the proportion of CCDC6-RET was observed in acquired RET-rearranged patients (47.3% vs. 22.5%, P < 0.001). The median progression-free survival (PFS) of patients harboring RB1 and TP53 double-mutations (5.5 vs. 10.0 months, P = 0.020) or ERBB2 amplification (5.6 vs. 10.0 months, P = 0.041) was significantly shorter than the wild-type counterparts. Moreover, we identified that RET fusions were more likely associated with acquired resistance (AR) to third-generation EGFR-TKIs than previous generations of EGFR-TKIs.

CONCLUSIONS

In conclusion, we depicted the mutational profiles of NSCLC patients who harbor RET fusions at baseline or after resistance to EGFR-TKIs. Furthermore, our results suggest that RET fusions mediate secondary resistance to third-generation EGFR-TKIs and might be associated with poor prognosis in patients with NSCLC.

LIBRETTO-432, a phase III study of adjuvant selpercatinib or placebo in stage IB-IIIA RET fusion-positive non-small-cell lung cancer

Selpercatinib, a first-in-class, highly selective and potent central nervous system-active RET kinase inhibitor demonstrated clinically meaningful activity with manageable toxicity in pretreated and treatment-naive advanced/metastatic RET fusion-positive non-small-cell lung cancer (NSCLC). LIBRETTO-432 is a global, randomized, double-blind, phase III trial evaluating selpercatinib versus placebo in stage IB-IIIA, RET fusion-positive NSCLC, previously treated with definitive surgery or radiation; participants must have undergone available anti-cancer therapy (including chemotherapy or durvalumab) or not be suitable for it, per investigator's discretion. The primary end point is investigator-assessed event-free survival (EFS) in the primary analysis population (stage II-IIIA RET fusion-positive NSCLC). Key secondary end points include EFS in the overall population, overall survival, and time to distant disease recurrence in the central nervous system.

Ultrasound images-based deep learning radiomics nomogram for preoperative prediction of RET rearrangement in papillary thyroid carcinoma

PURPOSE

To create an ultrasound -based deep learning radiomics nomogram (DLRN) for preoperatively predicting the presence of RET rearrangement among patients with papillary thyroid carcinoma (PTC).

METHODS

We retrospectively enrolled 650 patients with PTC. Patients were divided into the RET/PTC rearrangement group (n = 103) and the non-RET/PTC rearrangement group (n = 547). Radiomics features were extracted based on hand-crafted features from the ultrasound images, and deep learning networks were used to extract deep transfer learning features. The least absolute shrinkage and selection operator regression was applied to select the features of nonzero coefficients from radiomics and deep transfer learning features; then, we established the deep learning radiomics signature. DLRN was constructed using a logistic regression algorithm by combining clinical and deep learning radiomics signatures. The prediction performance was evaluated using the receiver operating characteristic curve, calibration curve, and decision curve analysis.

RESULTS

Comparing the effectiveness of the models by linking the area under the receiver operating characteristic curve of each model, we found that the area under the curve of DLRN could reach 0.9545 (95% confidence interval: 0.9133-0.9558) in the test cohort and 0.9396 (95% confidence interval: 0.9185-0.9607) in the training cohort, indicating that the model has an excellent performance in predicting RET rearrangement in PTC. The decision curve analysis demonstrated that the combined model was clinically useful.

CONCLUSION

The novel ultrasonic-based DLRN has an important clinical value for predicting RET rearrangement in PTC. It can provide physicians with a preoperative non-invasive primary screening method for RET rearrangement diagnosis, thus facilitating targeted patients with purposeful molecular sequencing to avoid unnecessary medical investment and improve treatment outcomes.

Phase 1/2 study of alectinib in RET-rearranged previously-treated non-small cell lung cancer (ALL-RET)

Background

Rearranged during transfection (RET) rearrangements occur in 1–2% of non-small cell lung cancers (NSCLCs). Alectinib administered at doses of 300 mg and 600 mg twice daily (BID) is approved for

ALK

rearranged NSCLC in Japan and other countries, respectively. Since alectinib has activity against RET, we conducted a phase (P) 1/2 study of alectinib to determine its activity in Japanese patients with

RET

rearranged NSCLC.

Methods

This study was a single-arm, open-label, multi-institutional P1/2 trial. Previously treated patients with RET-rearranged NSCLC, screened by nation-wide network (LC-SCRUM-Japan), were recruited. In P1, alectinib (600 or 450 mg BID) was administered following a 3+3 design and its safety was assessed. During P2, alectinib was administered at the recommended dose (RD) determined in P1. The primary endpoint was the objective response rate (ORR) in RET inhibitor-naïve patients treated with the RD of alectinib.

Results

Thirty-four patients were administered alectinib. In cohort 1 (600 mg BID) of P1, we observed 5 dose-limiting toxicities (DLTs), including grade 3 rash and thromboembolic event, in 3 of 6 patients. In cohort 2 (450 mg BID), we observed no DLTs in 3 patients. Pharmacokinetic analysis revealed that AUC_0–10 to 600 mg BID was higher than that previously reported in global trials. We determined 450 mg BID as the RD for P2. In 25 RET inhibitor-naïve patients, one achieved an objective response (4%) and 13 achieved disease control at 8 weeks (52%). The median progression-free survival (PFS) was 3.4 months (95% CI, 2.0–5.4), while the median overall survival was 19.0 months (5.4–NE). We observed grade 3 adverse events (AEs) (4%) including pneumonitis in P2.

Conclusions

Alectinib exerts limited activity against RET-rearranged NSCLC. Further investigation to elucidate the mechanisms underlying sensitivity and resistance of RET inhibitors is required to improve outcomes for these patients.

Phase III study of selpercatinib versus chemotherapy ± pembrolizumab in untreated RET positive non-small-cell lung cancer

Selpercatinib, a novel, highly selective and potent, inhibitor of RET, demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pretreated and treatment-naive RET fusion-positive non-small-cell lung cancer patients in a Phase I/II clinical trial. LIBRETTO-431 (NCT04194944) is a randomized, global, multicenter, open-label, Phase III trial, evaluating selpercatinib versus carboplatin or cisplatin and pemetrexed chemotherapy with or without pembrolizumab in treatment-naive patients with locally advanced/metastatic RET fusion-positive nonsquamous non-small-cell lung cancer. The primary end point is progression-free survival by independent review. Key secondary end points include overall survival, response rate, duration of response and progression-free survival. Clinical trial registration: NCT04194944 (ClinicalTrials.gov).

Molecular Characterization and Clinical Outcomes in RET-Rearranged NSCLC

INTRODUCTION

RET rearrangements are an emerging targetable oncogenic fusion driver in NSCLC. However, the natural history of disease and activity of different classes of systemic therapy remain to be defined. Furthermore, molecular testing for RET is not yet routine, and the optimal method of testing is unclear. We present a comparative analysis of molecular profiling with fluorescence in situ hybridization (FISH) or next-generation sequencing (NGS) and treatment outcomes.

METHODS

This study was a retrospective analysis of patients treated at the National Cancer Centre Singapore. Baseline demographics and treatment outcomes were collected.

RESULTS

A total of 64 patients were included, with a median age of 62 years (range: 25-85), 56% were women, 77% were of Chinese ethnicity, 95% had adenocarcinoma, and 69% were never smokers. RET rearrangement was detected by FISH in 30 of 34 patients (88%), NGS in 40 of 43 patients (93%), and with discordant results in seven of 13 patients (54%) tested with both methods. Of 61 patients with stage IIIB/IV or recurrent disease, prevalence of central nervous system metastases was 31% and 92% received palliative systemic therapy. Overall survival was prolonged in patients treated with a selective RET tyrosine kinase inhibitor versus untreated patients (median 49.3 versus 15.3 mo; hazard ratio [HR]: 0.16, 95% confidence interval [CI]: 0.06-0.40, p < 0.001). However, it was not different in patients treated with immunotherapy versus untreated patients (median 37.7 versus 49.3 mo; HR: 1.30, 95% CI: 0.53-3.19, p = 0.53). Overall survival was also prolonged in patients with CCDC6-RET fusion versus those with KIF5B-RET fusion (median 113.5 versus 37.7 mo; HR: 0.12, 95% CI: 0.04-0.38, p = 0.009).

CONCLUSIONS

In RET-rearranged NSCLC, selective RET tyrosine kinase inhibitor therapy is associated with improved survival outcomes, especially in patients with CCDC6-RET fusion. However, immunotherapy has poor efficacy. NGS and FISH testing methods may also result in substantial discordance.

Characteristics and outcomes of RET-rearranged Korean non-small cell lung cancer patients in real-world practice

OBJECTIVE

Since the first discovery of rearranged during transfection (RET) fusion in lung adenocarcinoma in 2011, two tyrosine kinase inhibitors, namely vandetanib and cabozantinib, are currently available. Despite favorable outcomes in systemic control, the intracranial therapeutic response remains insufficient. In this study, the clinical characteristics and outcomes of non-small cell lung cancer (NSCLC) patients with RET rearrangements were analyzed.

METHODS

Patients with NSCLC harboring RET fusion who received treatment between January 2006 and January 2018 were analyzed. RET rearrangement was identified by FISH or NGS.

RESULTS

A total of 59 patients were identified. About half of the patients were female (47.5%) and never smokers (50.9%). Most patients had adenocarcinoma (89.8%). A total of 17 patients (28.8%) had an intracranial lesion at the initial diagnosis of stage IV disease, and 11 additional patients (18.6%) developed intracranial metastases during follow-up. The median time to development of intracranial metastases was 19.0 months (95% CI: 9.6-28.5), resulting in a >60% cumulative incidence of brain metastasis at 24 months. The systemic efficacy of pemetrexed-based regimens was favorable with progression-free survival of 9.0 (95% CI: 6.9-11.2) and OS of 24.1 (95% CI: 15.2-33.0) months. The median progression-free survival for vandetanib and immunotherapy was 2.9 (95% CI: 2.0-3.8) and 2.1 (95% CI: 1.6-2.6) months, respectively.

CONCLUSIONS

Given the likelihood of RET-rearranged NSCLC progressing to intracranial metastases and the absence of apparent clinical benefit of currently available targeted or immunotherapeutic agents, development of novel treatment with higher selectivity and better penetration of the blood-brain barrier remains a priority.

RET-rearranged non-small-cell lung cancer and therapeutic implications

First-line tyrosine kinase inhibitors are standard of care for non-small-cell lung cancers (NSCLC) harbouring an epidermal growth factor receptor mutation, anaplastic lymphoma kinase fusion or c-ros oncogene 1 rearrangement. Other targetable oncogenic drivers have been identified but testing for these is neither funded nor commonly performed in Australia. Using a case example, we discuss the importance of considering several other genomic aberrations in our population, such as rearrangements in the RET proto-oncogene, which occur in 1-2% of lung adenocarcinoma. New oncogenic drivers and corresponding targeted agents are constantly being discovered; these will continue to refine the treatment of non-small-cell lung cancer in the era of precision medicine.

Association of genetic and immuno-characteristics with clinical outcomes in patients with RET-rearranged non-small cell lung cancer: a retrospective multicenter study

Background

Rearranged during transfection (RET) has been proven to be a tumorigenic target in non-small cell lung cancers (NSCLCs). In RET-rearranged NSCLCs, molecular features and their impact on prognosis were not well illustrated, and the activity of mainstay therapeutics has not currently been well compared.

Methods

Patients diagnosed with NSCLCs with RET rearrangements were analyzed for concomitant mutations, tumor mutation burden (TMB), PD-L1 expression, T cell receptor repertoire and clinical outcomes with chemotherapy, immune checkpoint inhibitors (ICIs), and multikinase inhibitors (MKIs).

Results

Among 129 patients with RET-rearranged NSCLC who were analyzed, 41.1% (53/129) had co-occurring genetic alterations by next-generation sequencing, and concomitant TP53 mutation appeared most frequently (20/53, 37.7%). Patients with concurrent TP53 mutation (n = 15) had shorter overall survival than those without (n = 30; median, 18.4 months [95% CI, 8.6–39.1] vs 24.8 months [95% CI, 11.7–52.8]; P < 0.05). Patients with lower peripheral blood TCR diversity (n = 5) had superior overall survival compared with those with higher diversity (n = 6; median, 18.4 months [95% CI, 16.9–19.9] vs 4.8 months [95% CI, 4.5–5.3]; P = 0.035). An association with overall survival was not observed for PD-L1 expression nor for tumor mutation burden level. Median progression-free survival was not significantly different across chemotherapy, ICIs, and MKIs (median, 3.5 vs 2.5 vs 3.8 months). For patients treated with ICIs, the disease control rate was 60% (6/10) and the objective response rate was 20% (2/10).

Conclusions

RET-rearranged lung cancers can be heterogeneous in terms of concomitant genetic alterations. Patients with concurrent TP53 mutation or high peripheral blood TCR repertoire diversity have relatively inferior overall survival in this series. Outcomes with traditional systemic therapies in general are suboptimal.

Imaging Features and Patterns of Metastasis in Non-Small Cell Lung Cancer with RET Rearrangements

Rearranged during transfection proto-oncogene (RET) fusions represent a potentially targetable oncogenic driver in non-small cell lung cancer (NSCLC). Imaging features and metastatic patterns of advanced RET fusion-positive (RET+) NSCLC are not well established. Our goal was to compare the imaging features and patterns of metastases in RET+, ALK+ and ROS1+ NSCLC. Patients with RET+, ALK+, or ROS1+ NSCLC seen at our institution between January 2014 and December 2018 with available pre-treatment imaging were identified. The clinicopathologic features, imaging characteristics, and the distribution of metastases were reviewed and compared. We identified 215 patients with NSCLC harboring RET, ALK, or ROS1 gene fusion (RET = 32; ALK = 116; ROS1 = 67). Patients with RET+ NSCLC were older at presentation compared to ALK+ and ROS1+ patients (median age: RET = 64 years; ALK = 51 years, p < 0.001; ROS = 54 years, p = 0.042) and had a higher frequency of neuroendocrine histology (RET = 12%; ALK = 2%, p = 0.025; ROS1 = 0%, p = 0.010). Primary tumors in RET+ patients were more likely to be peripheral (RET = 69%; ALK = 47%, p = 0.029; ROS1 = 36%, p = 0.003), whereas lobar location, size, and density were comparable across the three groups. RET+ NSCLC was associated with a higher frequency of brain metastases at diagnosis compared to ROS1+ NSCLC (RET = 32%, ROS1 = 10%; p = 0.039. Metastatic patterns were otherwise similar across the three molecular subgroups, with high incidences of lymphangitic carcinomatosis, pleural metastases, and sclerotic bone metastases. RET+ NSCLC shares several distinct radiologic features and metastatic spread with ALK+ and ROS1+ NSCLC. These features may suggest the presence of RET fusions and help identify patients who may benefit from further molecular genotyping.

Association Between RET Fusions and Efficacy of Pemetrexed-based Chemotherapy for Patients With Advanced NSCLC in China: A Multicenter Retrospective Study

BACKGROUND

Rearranged during transfection (RET) proto-oncogene gene fusions are rare in non-small-cell lung cancer (NSCLC). We compared the efficacy of pemetrexed-based chemotherapy with other chemotherapy regimens in patients with NSCLC with different RET fusion subtypes.

PATIENTS AND METHODS

A retrospective, multicenter study of patients with pathologically confirmed stage IIIB/IV lung adenocarcinomas was conducted. RET rearrangements were detected using next generation sequencing. We analyzed the clinical characteristics of patients with RET-rearranged NSCLC and the efficacy of chemotherapy regimens. We also evaluated the efficacy between groups of patients with and without KIF5B-RET-rearranged lung cancer.

RESULTS

We evaluated 62 patients with NSCLC and RET rearrangements, including 41 with KIF5B-RET, 15 with CCDC6-RET, and 6 with other rare fusion subtypes. Of these 62 patients, 50 had stage IIIB/IV. We also evaluated 40 patients with first-line chemotherapy information available. The median progression-free survival was significantly different between those receiving pemetrexed-based chemotherapy and those receiving other chemotherapy regimens (9.2 vs. 5.2 months; P = .007). The median progression-free survival for patients with KIF5B-RET fusion and non-KIF5B-RET fusion was not significantly different statistically (7.8 vs. 11.2 months; P = .847). For second-line chemotherapy, a statistically significant difference was found between the chemotherapy regimens (4.9 vs. 2.8 months; P = .049). Survival follow-up data were available for 38 patients with advanced NSCLC. The median overall survival was 26.4 months. The overall survival of the patients with RET-rearranged NSCLC who had received pemetrexed-based chemotherapy versus no pemetrexed-based chemotherapy was 35.2 versus 22.6 months (P = .052). No difference in survival was observed between the patients with KIF5B-RET and non-KIF5B-RET rearrangements.

CONCLUSIONS

Pemetrexed-based treatment should be considered first when selecting the chemotherapy regimen for patients with NSCLC and RET rearrangements.

Intraductal Carcinoma of Salivary Glands Harboring TRIM27-RET Fusion with Mixed Low Grade and Apocrine Types

Intraductal carcinomas (IDCs) of salivary gland are rare neoplasms. Here, we report a case of IDCs harboring TRIM27-RET fusion with mixed low grade and apocrine types. A 79-year-old male presented with slowly-growing left parotid mass for 2.5 years. Histologically, the tumor demonstrated two distinct morphologies; a classic intercalated duct and low grade apocrine component. The intercalated duct component was positive for S100, SOX10 and vimentin, and negative for DOG-1 and HER2. The apocrine component was positive for androgen receptor (AR) and focally positive for HER2. The tumor harbored a TRIM27-RET fusion by FISH, and was negative for ETV6 and PLAG1 rearrangements. This case is unusual in that it displays two true phenotypically distinct components, which has only rarely been reported. This is the first report of intraductal carcinoma with two true phenotypically distinct components composed of low-grade and apocrine types with RET rearrangement and TRIM27-RET fusion.

Frequency of Brain Metastases and Multikinase Inhibitor Outcomes in Patients With RET-Rearranged Lung Cancers

INTRODUCTION

In ret proto-oncogene (RET)-rearranged lung cancers, data on the frequency of brain metastases and, in particular, the outcomes of multikinase inhibitor therapy in patients with intracranial disease are not well characterized.

METHODS

A global, multi-institutional registry (cohort A, n = 114) and a bi-institutional data set (cohort B, n = 71) of RET-rearranged lung cancer patients were analyzed. Patients were eligible if they had stage IV lung cancers harboring a RET rearrangement by local testing. The incidence of brain metastases and outcomes with multikinase inhibitor therapy were determined.

RESULTS

The frequency of brain metastases at the time of diagnosis of stage IV disease was 25% (95% confidence interval [CI]: 18%-32%) in all patients from both cohorts. The lifetime prevalence of brain metastasis in stage IV disease was 46% (95% CI: 34%-58%) in patients for whom longitudinal data was available. The cumulative incidence of brain metastases was significantly different (p = 0.0039) between RET-, ROS1-, and ALK receptor tyrosine kinase (ALK)-rearranged lung cancers, with RET intermediate between the other two groups. Although intracranial response data was not available in cohort A, the median progression-free survival of multikinase inhibitor therapy (cabozantinib, vandetanib, or sunitinib) in patients with brain metastases was 2.1 months (95% CI: 1.3-2.9 months, n = 10). In cohort B, an intracranial response was observed in 2 of 11 patients (18%) treated with cabozantinib, vandetanib (± everolimus), ponatinib, or alectinib; the median overall progression-free survival (intracranial and extracranial) was 3.9 months (95% CI: 2.0-4.9 months).

CONCLUSIONS

Brain metastases occur frequently in RET-rearranged lung cancers, and outcomes with multikinase inhibitor therapy in general are suboptimal. Novel RET-directed targeted therapy strategies are needed.

Characterization of Computed Tomography Imaging of Rearranged During Transfection-rearranged Lung Cancer

BACKGROUND

Rearranged during transfection (RET)-rearranged non-small-cell lung cancer (NSCLC) is relatively rare and the clinical and computed tomography (CT) image characteristics of patients with an advanced disease stage have not been well documented.

PATIENTS AND METHODS

We identified patients with advanced-stage RET-rearranged NSCLC treated in the Cancer Institute Hospital, Japanese Foundation for Cancer Research, and analyzed the clinical and CT imaging characteristics.

RESULTS

In 21 patients with advanced RET-rearranged NSCLC, RET rearrangements were identified using fluorescence in situ hybridization and/or reverse transcriptase-polymerase chain reaction. The fusion partner genes were identified as KIF5B (57%), CCDC6 (19%), and unknown (24%). CT imaging showed that 12 primary lesions (92%) were peripherally located and all were solid tumors without ground-glass, air bronchograms, or cavitation. The median size of the primary lesions was 30 mm (range, 12-63 mm). Of the 18 patients with CT images before initial chemotherapy, 12 (67%) showed an absence of lymphadenopathy. Distant metastasis included 13 with pleural dissemination (72%), 10 with lung metastasis (56%), 8 with bone metastasis (44%), and 2 with brain metastasis (11%).

CONCLUSION

Advanced RET-rearranged NSCLC manifested as a relatively small and peripherally located solid primary lesion with or without small solitary lymphadenopathy. Pleural dissemination was frequently observed.

Vandetanib in pretreated patients with advanced non-small cell lung cancer-harboring RET rearrangement: a phase II clinical trial

Background

Chromosomal rearrangements involving RET, which are found in about 1% of non-small cell lung cancer (NSCLC), define a unique molecular subset. We performed this study to examine the efficacy and safety of vandetanib 300 mg daily in this patient population.

Patients and methods

This study was a multi-center, open-label, phase II clinical trial. Patients were enrolled if they had metastatic or recurrent NSCLC with a RET rearrangement, which was confirmed by fluorescence in situ hybridization, had progressive disease against platinum-based doublet chemotherapy, and had a performance status of 0-2. The primary endpoint was the objective response rate.

Results

A total of 18 patients were enrolled in this study between July 2013 and October 2015. Patients were aged 35-71 years; three had a performance status of 2, and the majority were a heavily pretreated population (≥ two different previous chemotherapy regimens in 72% of the patients). Among the 17 evaluable patients, three had a partial response (objective response rate = 18%) and eight had a stable disease (disease control rate = 65%). Among these patients, the partial response or disease stabilization was durable for more than 6 months in eight patients. Vandetanib also showed a progression-free survival of 4.5 months, and an overall survival of 11.6 months during a median follow-up duration of 14 months. The safety profile was comparable with previous studies of vandetanib. Most vandetanib-related adverse events were mild with prevalent hypertension and rash (in >70% of patients). Grade 3 toxicity included hypertension (n = 3), QT prolongation (2), and elevation of aminotransferases (1), and as a consequence the dose was reduced in four patients. There were no adverse events associated with grade 4 or 5 toxicity.

Conclusion

Vandetanib is moderately active in pretreated patients with advanced NSCLC-harboring RET rearrangements.

Clinical and Translational Implications of RET Rearrangements in Non-Small Cell Lung Cancer

Since the discovery in 2012 of rearranged during transfection proto-oncogene gene (RET) rearrangements in NSCLC, at least 12 different fusion variants have been identified, with kinesin family member 5B gene (KIF5B)-RET being the most frequent and the best characterized. Unlike ALK receptor tyrosine kinase gene (ALK) and ROS1 rearrangements, RET fusion genes cannot be adequately detected by immunohistochemistry (IHC), although fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction are fully complementary diagnostic tools. In large retrospective studies, RET rearrangements correlate with adenocarcinoma histologic subtype, never-smoking status, younger age, more advanced disease stage, potentially higher chemosensitivity (in particular, to pemetrexed-based regimens), and coexistence of other genomic alterations. To date, several preclinical models, clinical trials, and retrospective studies have investigated multitarget inhibitors with anti-rearranged during transfection proto-oncogene (RET) activity in patients with RET-rearranged lung cancer. In the clinical setting, the benefit in terms of response (16%-47%) and progression-free survival (2-7 months) is clearly not comparable to that seen with other targeted agents in oncogene-addicted NSCLC. Furthermore, multikinase agents showed high rates of severe toxicities, leading to frequent dose reduction and drug discontinuation. To date, no definitive conclusions about a potentially different impact of anti-RET therapies according to RET fusion variants have been drawn on account of discordant data coming mostly from small subgroup analyses. Importantly, the absence of a striking clinical benefit in RET oncogene-addicted NSCLC underscores the clear need for development of more selective and potent RET inhibitors and for better characterization of concomitant genomic alterations and mechanisms of resistance to RET inhibition in patients with lung cancer.

Clinicopathological Characteristics of RET Rearranged Lung Cancer in European Patients

INTRODUCTION

Rearrangements of RET are rare oncogenic events in patients with non-small cell lung cancer (NSCLC). While the characterization of Asian patients suggests a predominance of nonsmokers of young age in this genetically defined lung cancer subgroup, little is known about the characteristics of non-Asian patients. We present the results of an analysis of a European cohort of patients with RET rearranged NSCLC.

METHODS

Nine hundred ninety-seven patients with KRAS/EGFR/ALK wildtype lung adenocarcinomas were analyzed using fluorescence in situ hybridization for RET fusions. Tumor specimens were molecularly profiled and clinicopathological characteristics of the patients were collected.

RESULTS

Rearrangements of RET were identified in 22 patients, with a prevalence of 2.2% in the KRAS/EGFR/ALK wildtype subgroup. Co-occurring genetic aberrations were detected in 10 patients, and the majority had mutations in TP53. The median age at diagnosis was 62 years (range, 39-80 years; mean ± SD, 61 ± 11.7 years) with a higher proportion of men (59% versus 41%). There was only a slight predominance of nonsmokers (54.5%) compared to current or former smokers (45.5%).

CONCLUSIONS

Patients with RET rearranged adenocarcinomas represent a rare and heterogeneous NSCLC subgroup. In some contrast to published data, we see a high prevalence of current and former smokers in our white RET cohort. The significance of co-occurring aberrations, so far, is unclear.

1p/19q codeletion and RET rearrangements in small-cell lung cancer

The prognosis of small-cell lung cancer (SCLC) is poor despite reports suggesting modest improvement in survival. To date, chemotherapy remains the cornerstone treatment for SCLC patients, and many studies have focused on identifying the molecular characteristics of SCLC, which serve as the basis for precision treatments that improve the prognosis of SCLC. For instance, the therapeutic effect of temozolomide, recommended for patients with relapsed SCLC, is linked to 1p/19q codeletion in anaplastic oligodendroglial tumors. A subpopulation of SCLC patients may derive benefit from tyrosine kinase inhibitors targeting RET. In order to identify 1p/19q codeletion and RET rearrangement in SCLC patients, 32 SCLC resected specimens were retrospectively collected between 2008 and 2014 from the Zhejiang Cancer Hospital in People’s Republic of China. Fluorescence in situ hybridization was used to detect 1p/19q codeletion and RET rearrangement in the specimens. A 1p single deletion was detected in eight specimens, 19q single deletion was detected in three specimens, and only three specimens had a 1p/19q codeletion. None of the specimens had a RET rearrangement. The three patients whose specimens had a 1p/19q codeletion were alive after 58, 50, and 30 months of follow-up care. There was a trend toward prolonged overall survival for the patients with codeletion compared to no codeletion, 1p single deletion, 19q single deletion, and without 1p and 19q deletion (P=0.113, 0.168, 0.116, and 0.122, respectively). Our data showed that RET rearrangement may be not an ideal molecular target for SCLC therapies in People’s Republic of China. Instead, 1p/19q codeletion is a promising marker for a good prognosis and treatment with temozolomide in SCLC.

Clinical outcomes with pemetrexed-based systemic therapies in RET-rearranged lung cancers

BACKGROUND

RET rearrangements are targetable, oncogenic lung cancer drivers. While previous series have shown durable clinical benefit with pemetrexed-based therapies in ALK- and ROS1-rearranged lung cancers, the benefits of pemetrexed-based treatments in patients with RET-rearranged lung cancers relative to other genomic subsets have not previously been explored.

PATIENTS AND METHODS

A retrospective review of patients with pathologically confirmed stage IIIB/IV lung adenocarcinomas and evidence of a RET, ROS1, or ALK rearrangement, or a KRAS mutation was conducted. Patients were eligible if they received treatment with pemetrexed alone or in combination. The primary outcome of progression-free survival (PFS), and secondary outcomes of overall response rate (ORR, RECIST v1.1), time to progression (TTP), and time to treatment discontinuation were compared between RET-rearranged and groups of ROS1-rearranged, ALK-rearranged, and KRAS-mutant lung cancers.

RESULTS

We evaluated 104 patients. Patients with RET-rearranged lung cancers (n = 18) had a median PFS of 19 months [95% confidence interval (CI) 12-not reached (NR)] that was comparable with patients with ROS1- (23 months, 95% CI 14-NR, n = 10) and ALK-rearranged (19 months, 95% CI 15-36, n = 36) lung cancers, and significantly improved compared with patients with KRAS-mutant lung cancers (6 months, 95% CI 5-9, P < 0.001, n = 40). ORR (45%), median TTP (20 months, 95% CI 17-NR), and median time to treatment discontinuation (21 months, 95% CI 6-NR) in patients with RET-rearranged lung cancers were not significantly different compared with patients with ALK- and ROS1-rearranged lung cancers, and improved compared with patients with KRAS-mutant lung cancers.

CONCLUSION

Durable benefits with pemetrexed-based therapies in RET-rearranged lung cancers are comparable with ALK- and ROS1-rearranged lung cancers. When selecting therapies for patients with RET-rearranged lung cancers, pemetrexed-containing regimens should be considered.

From genotype to phenotype: Are there imaging characteristics associated with lung adenocarcinomas harboring RET and ROS1 rearrangements?

INTRODUCTION

Recurrent gene rearrangements are important drivers of oncogenesis in non-small cell lung cancers. RET and ROS1 rearrangements are each found in 1-2% of lung adenocarcinomas and represent distinct molecular subsets. This study assessed the computed tomography (CT) imaging features of patients with RET- and ROS1-rearranged lung cancers.

METHODS

Eligible patients included pathologically-confirmed lung adenocarcinomas of any stage with a RET or ROS1 rearrangement via fluorescence in-situ hybridization or next-generation sequencing, and available pre-treatment baseline imaging for review. A cohort of EGFR-mutant lung cancers was identified as a control group. CT features assessed included location, consistency, contour, presence of cavitation, and calcification of the primary tumor. Presence of an effusion, lung metastases, adenopathy and extrathoracic disease were recorded. The Wilcoxon rank-sum/Kruskal-Wallis and Fisher's exact tests were used to compare features between groups.

RESULTS

73 patients with lung adenocarcinomas were identified: 17 (23%) with ROS1 fusions, 25 (34%) with RET fusions and 31 (43%) with EGFR mutations. ROS1-rearranged lung cancers were more likely to present as peripheral tumors in comparison to EGFR-mutant lung cancers (32% vs. 65%, p=0.04). RET-rearranged lung cancers did not significantly differ from EGFR-mutant lung cancers radiographically. The consistency of the primary lesion for RET and ROS fusions and EGFR mutations were most frequently solid and spiculated.

CONCLUSIONS

Lung adenocarcinomas with RET and ROS1 fusions share many radiographic features and those with ROS1 fusions are more likely to present as peripheral lesions in comparison to EGFR-mutant lung cancers.