Analyzing the risk factors for disease progression within 2 years and histological transformation in patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone as first-line treatment: A 15-year follow-up of patients with advanced follicular lymphoma in JCOG0203

Follicular lymphoma (FL) is an indolent lymphoma that becomes aggressive due to histological transformation (HT), leading to reduced survival. Patients with FL have different clinical courses and various treatment options. Some patients exhibit shorter survival and experience disease progression within 24 months of diagnosis/treatment (POD24); the optimal treatment remains an unmet needs. Thus, identifying factors that predict shorter survival is essential to stratify treatment and prolong the survival of patients with FL. To analyze risk factors for POD24 and HT in patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) as first-line treatment, we performed this post-hoc analysis of patients with advanced indolent B-cell lymphoma in a randomized clinical trial wherein six cycles of R-CHOP were administered every 2-3 weeks. The primary analysis showed no differences in outcomes, which enabled the analysis of 248 patients with FL, assigned to two arms. All histopathological specimens from the 300 enrolled patients were reviewed by three expert hematopathologists. Multivariable analysis implicated Follicular Lymphoma International Prognostic Index (FLIPI) intermediate (odds ratio [OR] 2.531, 95% confidence interval [CI] 0.676-9.466) and high- (OR 2.236, 95% CI 0.160-31.226) risks, B symptoms (OR 2.091, 95% CI 0.747-5.851), and grade 3A (G3A) (OR 1.833, 95% CI 0.634-5.299) as risk factors for POD24. Furthermore, multivariable analysis through a median follow-up of 15.9 years implicated G3A (OR 2.628, 95% CI 0.806-8.575) and high-risk FLIPI (OR 4.401, 95% CI 0.186-104.377) as risk factors for HT. However, an analysis limited to the first 10 years revealed that the prognostic factors elucidated from the longer-term analysis had a greater impact on HT. G3A and high-risk FLIPI may independently predict POD24 and HT, thereby informing treatment stratification of patients with untreated advanced-stage FL in future trials, particularly to address the unmet needs of patients with POD24.

Histological sarcomatoid transformation in a lung adenocarcinoma patient following immune checkpoint blockade

Histological transformation is a phenomenon that is well described as one of the causes of tyrosine kinase inhibitor resistance in oncogene-driven non-small-cell lung cancer (NSCLC). The use of immune checkpoint inhibitors (ICIs) as a potential mechanism of acquired resistance to immunotherapy in NSCLC to small-cell lung cancer was also recently found. Here, we report the histological transformation of sarcomatoid carcinoma and metastasis in a lung adenocarcinoma patient without targetable genetic alterations who experienced long-term disease remission after nivolumab therapy. The patient subsequently developed rapid progression in the mediastinal and retroperitoneal lymph nodes, bones, and small intestine. Surgical resection of the small intestine lesion due to acute small intestine bleeding revealed the transformation of NSCLC to sarcomatoid carcinoma. The patient died 3 months after sarcomatoid carcinoma transformation and extensive disease progression, although he was rechallenged with immunotherapy. Genomic and immunohistochemical analyses revealed a comparable abundance of gene mutations and a limited number of immune cells in the tumor microenvironment, with low infiltration of CD8+ T cells, CD4+ T cells, regulatory T cells, and PD-L1+ macrophages in metastatic tumors, revealing a noninflamed immune microenvironment for ICI-resistant tumors.

R-CHOP treatment for patients with advanced follicular lymphoma: Over 15-year follow-up of JCOG0203

Anti-CD20 antibody in combination with chemotherapy extends overall survival (OS) in untreated advanced-stage follicular lymphoma (FL), yet the optimal associated therapy is unclear. Data on the cumulative incidence of secondary malignancies postrelapse after conventional immunochemotherapy are scarce. A long-term analysis of rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) as first-line treatment was conducted in a randomised clinical trial. A six-cycle R-CHOP regimen was administered every 2 or 3 weeks without rituximab maintenance. A prespecified evaluation was conducted 15 years after the completion of enrolment, following initial analysis results that showed no significant differences in outcomes at the 3-year mark. In-depth analyses were performed on the cohort of 248 patients with FL who were allocated to the two treatment arms. With a median follow-up period of 15.9 years, the 15-year OS was 76.2%. There were no protocol treatment-related deaths, nor were there any fatal infections attributable to subsequent lymphoma treatment. At 15 years, the cumulative incidence of non-haematological and haematological malignancies was 12.8% and 3.7% respectively. Histological transformation appeared after a median of 8 years. R-CHOP maintains safety and efficacy in patients with advanced FL over extended follow-up, making it a viable first-line option for patients with advanced-stage FL.

Mutational landscape in Waldenström macroglobulinemia evaluated using a next-generation sequencing lymphoma panel in routine clinical practice

Next-generation sequencing (NGS) affords comprehensive insights into the genomic landscape of lymphomas. We examined the mutational pattern in patients with Waldenström macroglobulinemia (WM) or lymphoplasmacytic lymphoma (LPL) as well as the diagnostic and clinical utility of a tailored NGS lymphoma panel. A consecutive series of 45 patients was reviewed and NGS analysis was performed as part of a routine diagnostic setup. The custom designed NGS panel assayed all coding sequences of 59 genes of known clinical significance in lymphoid neoplasms. The most frequently mutated genes were MYD88, CXCR4, BIRC3, CD79B, and ARID1A. Additional somatic mutations were detected in 17 genes with four mutations categorized as pathogenic or likely pathogenic. BIRC3 and TP53 mutations were associated with adverse clinical phenotypes. NGS performance for the MYD88L265P variant was 96% when compared to qPCR. In conclusion, targeted NGS provided important diagnostic and prognostic information in a routine clinical setting.

Histological transformation into SCLC: An important resistance mechanism of NSCLC upon immunotherapy

The phenomenon of histological transformation has been widely reported in advanced non-small cell lung cancer (NSCLC) with EGFR mutations following the failure of EGFR-TKI treatment. Recent evidence suggests that similar histological changes can also occur in advanced NSCLC without driver gene mutations after developing resistance to immunotherapy. In this review, it was found that 66.7% of cases with immunotherapy-induced histological transformation were classified as lung squamous cell carcinoma (LSCC), while histological conversion into lung adenocarcinoma (LUAD) without EGFR or ALK gene mutations has rarely been reported. There have been sporadic reports on the occurrence of mutual transformation between LUAD and LSCC. The histological conversion from NSCLC into small cell lung cancer (SCLC) appears to be significantly underestimated, likely due to the infrequency of re-biopsy following the development of immunotherapy resistance. Several studies have reported a close association between the transformation and mutations at TP53 and the RB1 splice site, as well as the loss of an FBXW7 mutation. However, the exact mechanisms underlying this conversion remain unclear. Currently, there is a lack of guidelines for the management of transformed SCLC from NSCLC following immunotherapy, with chemotherapy being the most commonly employed treatment approach.

IDO1 Protein Is Expressed in Diagnostic Biopsies from Both Follicular and Transformed Follicular Patients

Follicular lymphoma (FL) is a lymphoid neoplasia characterized by an indolent clinical nature. Despite generally favorable prognoses, early progression and histological transformation (HT) to a more aggressive lymphoma histology remain the leading causes of death among FL patients. To provide a basis for possible novel treatment options, we set out to evaluate the expression levels of indoleamine 2,3-dioxygenase 1 (IDO1), an immunoinhibitory checkpoint molecule, in follicular and transformed follicular biopsies. The expression levels of IDO1 were assessed using immunohistochemical staining and digital image analysis in lymphoma biopsies from 33 FL patients without subsequent HT (non-transforming FL, nt-FL) and 20 patients with subsequent HT (subsequently transforming FL, st-FL) as well as in paired high-grade biopsies from the time of HT (transformed FL, tFL). Despite no statistical difference in IDO1 expression levels seen between the groups, all diagnostic and transformed lymphomas exhibited positive expression, indicating its possible role in novel treatment regimens. In addition, IDO1 expression revealed a positive correlation with another immune checkpoint inhibitor, namely programmed death 1 (PD-1). In summary, we report IDO1 expression in all cases of FL and tFL, which provides the grounds for future investigations of anti-IDO1 therapy as a possible treatment for FL patients.

Transformation or tumor heterogeneity: Mutations in EGFR, SOX2, TP53, and RB1 persist in the histological rapid conversion from lung adenocarcinoma to small-cell lung cancer

The transformation from non-small-cell lung cancer (NSCLC) to small-cell lung cancer (SCLC) is one of the mechanisms of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) resistance. Previous studies exhibited that the median transformation time was 17.8 months for NSCLC to SCLC. Here we introduced a case of lung adenocarcinoma (LADC) with EGFR19 exon deletion mutation in which the pathological transformation emerged only 1 month after lung cancer surgery and receiving EGFR-TKI inhibitor. Eventually, the pathological examination confirmed the patient experienced a transformation from LADC to SCLC with EGFR, tumor protein p53 (TP53), RB transcriptional corepressor 1 (RB1), and SRY-box transcription factor 2 (SOX2) mutation. Although the transformation of LADC with EGFR-mutant into SCLC after targeted therapy was frequent, the pathological results of most patients were only biopsy specimens, which cannot rule out the existence of mixed pathological components of the primary tumor. In this case, the patient's postoperative pathology was sufficient to exclude the probability of mixed tumor components, confirming that the patient's pathological change was indeed transformation from LADC to SCLC. In addition, primary drug resistance in such a short time after surgery and osimertinib-targeted therapy has not been reported before. We detected the molecular state of this patient before and after SCLC transformation through targeted gene capture and high-throughput sequencing, and also found for the first time that the mutations of EGFR, TP53, RB1, and SOX2 continue to exist before and after transformation, but the mutation abundance is different. In our paper, the occurrence of small-cell transformation is affected largely by these gene mutations.

Transformation of indolent follicular lymphoma into diffuse large B-cell lymphoma - the molecular basis of "cancer aggressiveness"

BACKGROUND

Follicular lymphoma (FL) is the most common indolent non-Hodgkin's lymphoma in the Western world. It is an indolent disease in most patients, but about 20% of patients experience an early relapse after initial treatment, which is associated with shorter overall survival. A histological transformation into an aggressive lymphoma, most frequently diffuse large-cell B-lymphoma, represents another prognostically unfavorable event in the course of the disease. Thanks to recent genomic studies and mouse models, we are able to better understand the molecular nature of the FL onset and evolution of "aggressive" subclones of cells. Recently, deregulation of several molecular pathways associated with the histological transformation has also been described.

PURPOSE

This review summarizes the complex molecular mechanisms responsible for FL onset, progression, aggressiveness, and transformation. We believe that the observations in FL have some general implications for understanding the mechanisms leading to the evolution of cancer "aggressiveness," such as divergent evolution, intraclonal variability and tumor plasticity.

Intestinal Mucosa-Associated Lymphoid Tissue Lymphoma Transforming into Diffuse Large B-Cell Lymphoma in a Young Adult Patient with Neurofibromatosis Type 1: A Case Report

Background: Neurofibromatosis type 1 (NF1) is a hereditary cancer syndrome characterized by multiple café-au-lait macules on the skin. Lymphoproliferative malignancies associated with NF1 are limited, although the most common are brain tumors. Case presentation: A 22-year-old woman with NF1 was admitted due to abdominal pain and bloody diarrhea. Her laboratory data exhibited macrocytic anemia and elevated IgA levels. Image studies showed diffuse increased wall thickening in the transverse and descending colon without lymphadenopathy and hepatosplenomegaly. A colonoscopy revealed a hemorrhagic ulcerated mass. Pathological analysis of the tumor tissues confirmed IgA-expressing mucosa-associated lymphoid tissue (MALT) lymphoma with histological transformation. Moreover, whole-exome sequencing in tumor tissues and peripheral blood mononuclear cells identified a somatic frameshift mutation of the A20 gene, which represents the loss of function. The patient responded well to R-CHOP chemotherapy, but the disease relapsed after 1 year, resulting in a lethal outcome. Conclusions: MALT lymphoma in children and young adults is extremely rare and is possibly caused by acquired genetic changes. This case suggests a novel association between hereditary cancer syndrome and early-onset MALT lymphoma.

Clinical features and outcomes of patients with follicular lymphoma: A real-world study of 926 patients in China

Background

The data about the clinical features and outcomes of Chinese patients with follicular lymphoma (FL) are limited. Here, we conducted a retrospective study to explore the initial treatment strategies and clinical outcomes of Chinese patients with FL in the real world.

Method

This study included FL patients who were newly diagnosed in Tianjin Medical University Cancer Institute and Hospital from March 2002 to August 2020.

Results

A total of 926 FL patients were enrolled. The median age was 54 years old, and the majority of the Chinese FL patients had advanced-stage disease and Eastern Cooperative Oncology Group(ECOG) <1 but less frequently infiltrated bone marrow. After a median of 38-month follow-up, the 5-year progressive-free survival (PFS) and overall survival (OS) of grade1-3a were 57.8% and 88.7%, respectively, which both are similar to those reported in previous Chinese and Western studies. The co-existence at diagnosis of FL and diffuse large B-cell lymphoma (DLBCL) components (FL/DLBCL) was associated with poor outcomes. The FL grades and proportion of DLBCL component in FL/DLBCL did not have an impact on PFS and OS. The most common regimen with great efficacy and risk-benefit was RCHOP-like followed by R maintenance regimen. The 5-year cumulative hazard of histological transformation (HT) was 4.7% (95% CI, 3.5-5.9); median time to transformation was 23.5 months (range, 2-146 months) after diagnosis. Three-year survival following transformation was 55% (95% CI, 40-70). Patients with stage III-IV, elevated β2 microglobulin (β2-MG), and B symptoms seemed to be more prone to progress within 24 months of frontline therapy (POD24). The FLIPI-2 showed the highest specificity to predict POD24, reflecting the prediction of correctly classifying as low-risk patients, but the FLIPI had the highest sensitivity to predict the risk of progression for critical patients.

Conclusions

We revealed the clinical characteristics and outcomes of FL patients in the real world in China, which may provide novel data on prognostic factors and primary treatment of FL, applicable to routine clinical practice.

Histological Transformation after Acquired Resistance to the Third-Generation EGFR-TKI in Patients with Advanced EGFR-Mutant Lung Adenocarcinoma

Background and Objectives: Third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) is one of the standard-of-care therapies in patients with EGFR-mutant lung adenocarcinoma; however, acquired resistance inevitably developed. Despite the proposition of histological transformation being one of the resistance mechanisms, its incidence and influence on outcome remain unclear. Materials and Methods: This was a retrospective study conducted at Taichung Veterans General Hospital on patients with advanced EGFR-mutant lung adenocarcinoma receiving the third-generation EGFR-TKI. Only patients receiving rebiopsy were included in the analysis. Results: A total of 55 patients were studied. Eight patients (14.5%) showed histological transformation, including three small cell carcinoma, three squamous cell carcinoma, one large cell neuroendocrine carcinoma, and one with a mixture of adenocarcinoma and squamous cell carcinoma components. The median treatment duration of the third-generation EGFR-TKI before rebiopsy was numerically longer in patients with histological transformation than those without (16.0 vs. 10.9 months). Both the overall survival time from the start of third-generation EGFR-TKI initiation (30.8 vs. 41.2 months) and from rebiopsy (6.6 vs. 12.9 months) to mortality were numerically shorter amongst the transformed population. All patients in the transformed group did not respond to the next line of systemic treatment. One patient with histological transformation receiving local treatment for the metastatic site had a longer overall survival. Conclusions: Repeating biopsy to identify histological transformation should be considered in patients with progression to the third-generation EGFR-TKI. Histological transformations could contribute to the acquired resistance with the implication of a worse prognosis. Further studies are needed to determine the optimal therapy for these patients.

Squamous cell histological transformation in a lung adenocarcinoma patient (hyper) progressing upon immunotherapy

INTRODUCTION

In non-small cell lung cancer (NSCLC) histologic transformation upon immune checkpoint inhibitors (ICI) is rare.

CASE PRESENTATION

We described the case of a patient with early-stage lung adenocarcinoma who relapsed after surgery. At the time of relapse, he received chemo-radiotherapy, followed by consolidation immunotherapy. After 3 cycles the patient experienced disease hyperprogression for onset of a new lung mass, which resulted in squamous cell carcinoma. The preservation of an atypical mutation in the v-raf murine sarcoma viral oncogene homolog B1 (BRAF) gene in both the primary adenocarcinoma and the new squamous carcinoma suggests histological transformation, likely ICI-related.

DISCUSSION

We reviewed similar cases in literature, highlighting common patterns and substantial differences. For a deeper insight into inherent biological mechanisms, re-biopsy in case of atypical ICI response should be encouraged.

Case Report: Partial Response Following Nivolumab Plus Docetaxel in a Patient With EGFR Exon 20 Deletion/Insertion (p.N771delinsGF) Mutant Lung Adenocarcinoma Transdifferentiated From Squamous Cell Carcinoma

The histological transformation from lung squamous cell carcinoma (LUSC) to lung adenocarcinoma (LUAD) and p. N771delinsGF mutations in EGFR exon 20 (ex20) are exceedingly rare in non–small cell lung carcinoma (NSCLC). EGFR ex20 mutations are insensitive to EGFR tyrosine kinase inhibitors in NSCLC. Here, we present a 76-year-old male smoker harboring LUAD with a novel p. N771delinsGF deletion/insertion mutation in EGFR ex20 transdifferentiating from advanced LUSC after chemoradiotherapy. The patient presented reduced hydrothorax and relieved tightness with the treatment of nivolumab plus docetaxel and carboplatin after the failure of second-line chemotherapy. The case highlights the importance of rebiopsy and molecular retesting after the progression of lung cancer and supports the idea that the combination of immune checkpoint blockade and chemotherapy may be an attractive option for patients with EGFR ex20 mutations associated with LUSC–LUAD transformation.

NOTCH alteration in EGFR-mutated lung adenocarcinoma leads to histological small-cell carcinoma transformation under EGFR-TKI treatment

BACKGROUND

Molecular targeted therapy has been developed as an innovative treatment for metastatic cancer. Epidermal growth factor receptor (EGFR) mutation is one of the most important and frequent oncogenic drivers in non-small-cell lung cancer, and EGFR-tyrosine kinase inhibitors are indispensable drugs for mutation-positive patients. Currently, the acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is a problem, the mechanism of which has not been elucidated. The histological transformation from original adenocarcinoma to small-cell carcinoma is rare; however, it has been detected in many cases after EGFR-TKI treatment. This study aimed to evaluate mutational status in two different histological types and further elucidate the molecular pathogenesis.

METHODS

Three patients with EGFR-mutant lung cancer who underwent a histological transformation to small-cell carcinoma after growth factor receptor-TKI treatment were enrolled in this study. Two samples per patient were collected from histologically different lesions, and DNA samples were extracted from formalin-fixed, paraffin-embedded tumor tissues. The paired samples were subjected to next-generation sequencing of 160 cancer-related genes. Based on the sequencing results, the expression levels of related proteins were validated using reverse-transferase polymerase chain reaction and immunohistochemical staining.

RESULTS

The following five variants were common among the three cases: MTOR, JAK1, NOTCH2, CSF1R, and MAP2K2. The former four variants were additive to small-cell carcinoma, and the last variant was lost. Both TP53 and Rb1 alterations were detected in adenocarcinoma. Notch2 expression was negative in small-cell carcinoma in both reverse-transcriptase polymerase chain reaction analysis and immunohistochemical staining. ASCL1 expression increased after histological transformation detected using both methods in one case, only these samples were evaluable.

CONCLUSIONS

Notch and ASCL1 signaling are the master regulators of neuroendocrine differentiation in small-cell lung carcinoma. Our results suggest that the Notch-ASCL1 axis may also play an essential role in the transformation of small-cell carcinoma under TP53 and RB1 inactivation.

Clinico-biological features and outcome of patients with splenic marginal zone lymphoma with histological transformation

We describe 36 patients with splenic marginal zone lymphoma (SMZL) with transformation (SMZL‐T), including 15 from a series of 84 patients with SMZL diagnosed at the Hospital Clinic of Barcelona (HCB) and 21 diagnosed with SMZL‐T in other centres. In the HCB cohort, the cumulative incidence of transformation at 5 years was 15%. Predictors for transformation were cytopenias, hypoalbuminaemia, complex karyotype (CK) and both the Intergruppo Italiano Linfomi (ILL) and simplified Haemoglobin, Platelet count, lactate dehydrogenase (LDH) and extrahilar Lymphadenopathy (HPLL)/ABC scores (P < 0·05). The only independent predictor for transformation in multivariate analysis was CK [hazard ratio (HR) 4·025, P = 0·05]. Patients with SMZL‐T had a significantly higher risk of death than the remainder (HR 3·89, P < 0·001). Of the 36 patients with SMZL‐T, one developed Hodgkin lymphoma and 35 a diffuse large B‐cell lymphoma, 71% with a non‐germinal centre phenotype. The main features were B symptoms, lymphadenopathy, and high serum LDH. CK was observed in 12/22 (55%) SMZL‐T and fluorescence in situ hybridisation detected abnormalities of MYC proto‐oncogene, basic helix‐loop‐helix transcription factor (MYC), B‐cell leukaemia/lymphoma 2 (BCL2) and/or BCL6 in six of 14 (43%). In all, 21 patients received immunochemotherapy, six chemotherapy, one radiotherapy and three splenectomy. The complete response (CR) rate was 61% and the median survival from transformation was 4·92 years. Predictors for a worse survival in multivariate analysis were high‐risk International Prognostic Index (HR 5·294, P = 0·016) and lack of CR (HR 2·67, P < 0·001).

Secondary Hemophagocytic Lymphohistiocytosis With Epstein-Barr Virus-Associated Transformed Follicular Lymphoma: A Case Report and Literature Review

A 58-year-old male was admitted to our hospital due to lasting fever, progressive lymphadenopathy and bicytopenia, with a previously histological diagnosis of follicular lymphoma grade 3a with Epstein-Barr virus-encoded RNA positive one month ago. A second biopsy of axillary lymph node revealed concurrent diffuse large B-cell lymphoma with Epstein-Barr virus-encoded RNA positive. Another diagnosis of hemophagocytic lymphohistiocytosis secondary to Epstein-Barr virus positive diffuse large B-cell lymphoma was further concluded by clinical manifestation, laboratory test and atypical lymphocytes in peripheral-blood smear. After a pulse of steroid pre-phase treatment, the patient's clinical condition deteriorated and died in two weeks. The presence of Epstein-Barr virus infection in patients with follicular lymphoma is associated with more aggressive clinical course and increased risk of high-grade transformation. Hemophagocytic lymphohistiocytosis in response to Epstein-Barr virus infection or lymphoma remains fatal. Early diagnosis and initiation of treatment may improve the outcome.

Case Report: EGFR-Positive Early-Stage Lung Adenocarcinoma Transforming to Squamous Cell Carcinoma After TKI Treatment

The histological transformation from epidermal growth factor receptor (EGFR)-mutated adenocarcinoma (ADC) to squamous cell carcinoma (SCC) after tyrosine kinase inhibitor (TKI) treatment is rare. We present a case of a patient who transitioned from early-stage primary lung ADC with partial squamous differentiation, EGFR mutation and amplification, to adrenal gland metastasis as SCC with EGFR amplification disappearance 115-months after surgery, during which gefitinib and local radiotherapy were utilized for the metastasis in the right femoral head and mediastinal lymph nodes. This case might indicate a possible mechanism of EGFR inhibition resistance with SCC transition and EGFR amplification loss from the initially well-responding ADC, especially those with SCC or partial squamous differentiation. The optimal post-progression therapy for ADC-SCC patients is challenging and further studies are needed.

Histological transformation of lung adenocarcinoma to small cell lung cancer with mutant C797S conferring acquired resistance to osimertinib

Epidermal growth factor receptor (EGFR) gene-mutated non-small cell lung cancer may initially respond to EGFR tyrosine kinase inhibitors (TKIs), but may subsequently become resistant; however, the resistance mechanisms remain unclear. We report a rare case of acquired resistance to osimertinib associated with transformation to small cell lung cancer (SCLC) with cis-C797S mutation. A man with recurrent lung adenocarcinoma harboring an EGFR exon 19 deletion received erlotinib for 10 months following curative surgery and adjuvant chemotherapy. However, he switched to osimertinib after repeat biopsy showed EGFR exon 19 deletion and T790M mutation leading to erlotinib resistance. His disease progressed after 15 months and repeat biopsy showed SCLC. Next-generation sequencing of peripheral blood detected EGFR exon 19 deletion, T790M mutation, cis-C797S mutation, and RB1 inactivation. The tumor was reduced after four cycles of etoposide and cisplatin and his respiratory symptoms improved. However, computed tomography after six cycles of chemotherapy showed multiple bilateral lung lesions, and single-photon emission computed tomography showed bone metastasis. The patient received paclitaxel plus cisplatin for two cycles with partial response. Because heterogeneous genetic and phenotypic mechanisms of TKI-resistance may occur at different times and locations, histopathological and molecular testing both provide evidence to support appropriate treatment.

Case Report: A Case Report of a Histological Transformation of ALK-Rearranged Adenocarcinoma With High Expression of PD-L1 to Squamous Cell Carcinoma After Treatment With Alectinib

We report an anaplastic lymphoma kinase (ALK)-positive patient shows a poor response to the ALK inhibitor alectinib due to the high expression of programmed death-ligand 1 (PD-L1). After treatment with alectinib, the pathological form changed from adenocarcinoma into squamous cell carcinoma without novel genetic changes. This case may reveal a direct relationship between ALK mutation and a high level of PD-L1 expression.

Combination of tissue and liquid biopsy molecular profiling to detect transformation to small cell lung carcinoma during osimertinib treatment

Background:

Histological transformation of advanced non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is one of the mechanisms of resistance to third-generation tyrosine kinase inhibitors (TKIs), such as osimertinib. This acquired TKI resistance is linked to the high degree of tumor heterogeneity and adaptive cellular signaling pathways, including epidermal growth factor receptor (EGFR)-dependent pathways, observed in NSCLC.

Methods:

Here, we investigated a series of paired pre- and post-histological transformation biopsies obtained from three patients initially having a NSCLC with an EGFR^activating mutation treated with first-generation TKI, who then received osimertinib as second-line after EGFR^T790M resistance and, lastly, developed a histological transformation to SCLC. Both tissue and liquid biopsies were analyzed using large panel sequencing approaches at various time points to reconstruct the clonal evolutionary history of the tumor.

Results:

Our complementary analysis of tumor tissue and circulating tumor DNA samples allowed us to better characterize the histological and molecular alterations associated with resistance to osimertinib. SCLC transformation was linked to the presence of several concomitant gene alterations, including EGFR, TP53 and RB1, but also to specific signal bypass, such as EGFR and MET amplifications and activation of the PI3K/AKT/mTOR pathway.

Conclusion:

Our report emphasizes the mutational landscape of SCLC histological transformation and highlights the importance of combining tissue and liquid biopsy profiling before and during osimertinib treatment to predict such histological transformation.

Transformed mucosa-associated lymphoid tissue lymphomas: A single institution retrospective study including polymerase chain reaction-based clonality analysis

Given the lack of consistent data regarding the clinico-pathological features and clonal lymphomagenesis of patients with mucosa-associated lymphoid tissue (MALT) lymphoma and histological transformation (HT), we have systematically analysed 379 patients (32% gastric, 68% extra-gastric; median follow-up 52 months) diagnosed with HT at the Medical University Vienna 1999-2017, and reassessed tissues of identified patients by polymerase chain reaction (PCR)-based clonality analysis. HT was documented in 12/379 patients (3·2%) and occurred at a median time of 22 months (range; 6-202 months) after diagnosis of MALT lymphoma. By PCR-based clonality analysis, we detected a clear-cut clonal relationship of MALT lymphoma and diffuse large B-cell lymphoma (DLBCL) in 8 of 11 analysed cases proving that the large majority of DLBCL following MALT lymphoma are clonally-related and constitute a real transformation. Interestingly, HT occurred within the first 2·5 years after diagnosis in patients with clonal relationship, whereas time to aggressive lymphoma was longer in patients identified as clonally-unrelated (most likely secondary) lymphoma (82-202 months), suggesting that HT is an early event in this disease. Survival of patients with HT was poor with 6/12 dying at 1·5-33 months after HT, however, patients with localized gastric transformation had a superior outcome with only 1/6 dying due to progression of lymphoma.

Histological transformation in duodenal-type follicular lymphoma: a case report and review of the literature

Duodenal-type follicular lymphoma (DFL) is a rare variant of follicular lymphoma (FL) characterized by distinctive clinical features such as localization and favorable prognosis. We herein report a case of DFL in which histological transformation into diffuse large B-cell lymphoma developed 7 years after diagnosis. The transformed lymphoma was refractory to chemotherapy, and the patient passed away due to disease progression. To date, there have been only a limited number of reported cases of histological transformation of DFL, and the clinical outcomes of those cases except our present case have been favorable, with good responses to chemotherapy. Although the histological transformation of DFL is a rare event, the clinical course of the present case suggested that it would be a fatal event and underscore the importance of the life-long management of DFL. Further accumulation of cases is required to elucidate its incidence, characteristics, and prognosis.

Transformed follicular lymphoma in the rituximab era: A report from the Spanish Lymphoma Oncology Group

Follicular lymphoma (FL) is the second most common non-Hodgkin lymphoma (NHL) subtype. The histological transformation (HT) of FL is an event considered frequent in the natural history of this tumor. We studied the transformation rates, predictive factors, and treatment characteristics that may impact in the survival of patients with FL and HT. A total of 1074 patients diagnosed with FL were prospectively enrolled from 1990 to 2016 in a Spanish registry. Sixty-four HTs were recorded based on clinical criteria (55%) or histological confirmation (45%). The cumulative incidence rate of transformation at 5 years is 7.3%. The 5-year overall survival (OS) without HT was 85% (95% confidence interval [CI], 70%-90%) vs 66% (95% CI, 51%-76%; P = 0.0012) with HT. Factors associated with HT were elevated lactate dehydrogenase (LDH) (odds ratio [OR] 1.83), intermediate-high Follicular lymphoma international prognostic index (FLIPI) (OR 2.16-OR 3.21), B symptoms (OR 2.46), or Eastern Cooperative Oncology Group (ECOG) 1 (OR 2.35). Treatment options related to HT were "watch and wait" or no rituximab or anthracyclines initially. A 5-year OS for patients treated with chemotherapy before HT was 55% (95% CI, 38%-69%) versus 81% (95% CI, 53%-93%; P = 0.009) for those who had not received it. The HT rate has decreased after the introduction of rituximab, as has been previously described. The timing of this treatment had an impact on the survival of these patients.

Novel acquisitions on biology and management of transformed follicular lymphoma

Follicular lymphoma (FL) generally has an indolent clinical course, but in some patients, a histological transformation (HT) into aggressive entities may take place and often lead to a poorer survival. The rituximab era has seen an improved outcome of FL, including those with HT. The current treatment strategies for transformed FL are based on immunochemotherapy for the cases with HT at the time of diagnosis or as the first event after watchful waiting. Patients transforming after prior treatment of FL usually benefit from autologous stem cell transplant. Unfortunately, early assessment of the transformation risk remains elusive. Recent studies delved the mechanisms of HT, showing that this is a complex process, resulting from a number of epigenetic and genetic lesions occurring in the tumour cell population as well as progressive changes in the tumour microenvironment. This novel knowledge has prompted clinical investigations on a variety of new therapeutic strategies.

A rare case of squamous cell carcinoma lung with multiple locoregional recurrences and histological transformation

A 52-year-old female nonsmoker with localized squamous cell carcinoma (T3N1M0) of lung underwent lobectomy with adjuvant chemotherapy. Two years later, the patient had her first locoregional recurrence with adenosquamous cell carcinoma, and pneumonectomy with adjuvant chemotherapy rendered her disease free. Subsequent isolated locoregional recurrence with squamous cell carcinoma 18 months later was treated with chemoradiotherapy and had a complete response. Patient yet again had locoregional recurrence after 4 years and had progressive disease despite subsequent multiple line of treatment with platinum-based chemotherapy, stereotactic body radiation therapy, and nivolumab. This case is unique in presentation due to prolonged survival with multiple line of treatment of recurrent locoregional tumor without distant metastasis and alteration in the histology of tumor during illness.

Follicular lymphoma: State-of-the-art ICML workshop in Lugano 2015

The 13th International Conference on Malignant Lymphoma held in Lugano in June 2015 was preceded by a closed workshop (organized in collaboration with the American Association for Cancer Research and the European School of Oncology) with the aim of developing an up-to-date understanding of the biology of follicular lymphoma and the clinical implications of new findings in the field. Discussed topics included the mutational spectrum at diagnosis, the clinical correlates of genetic and epigenetic alterations, the mechanisms of clonal evolution and histological transformation, the cross talk between tumor cells and microenvironment, and the development of novel treatments. This report represents a summary of the workshop.

Histological transformation from gastric mucosa-associated lymphoid tissue lymphoma to gastric diffuse large B-cell lymphoma

This study evaluated the clinical features, treatment and prognosis in Chinese patients with histological transformation (HT) from gastric mucosa-associated lymphoid tissue lymphoma to gastric diffuse large B-cell lymphoma. We reviewed the medical records of 71 patients diagnosed with HT between 2001 and 2013, retrospectively. Patients had a median age of 56 years. The ratio of sex (male:female) was 1.3:1. The clinical course was often insidious, lacking specific clinical presentation. Macroscopically, the antrum was the most commonly involved site. Thirty-one patients (45%) presented at stage I, and 25 (35%) presented with local (18/71, 25%) or distant (7/71, 10%) nodal involvement. There were also stage IIE (9/71, 12%) and stage IV (6/71, 8%) patients with advanced stages. For all 71 patients, the 5-year progression-free survival (PFS) and overall survival (OS) estimates were 50 and 56%, respectively. There was no statistical difference in 5-year PFS and OS estimates between patients receiving Helicobacter pylori (H. pylori) containing eradication (HPE) (p=0.189) and those receiving non-HPE (p=0.359). Upon the Cox regression model, advanced stages were the only independent prognostic factors associated with shorter PFS, and m-IPI was independently associated with shorter PFS and OS. There was no specific clinical manifestation for patients with HT. HPE is thus a promising therapeutic approach for such patients. Moreover, advanced stages and m-IPI significantly influenced patient outcome.

Follicular lymphomas and their transformation: Past and current research

INTRODUCTION

Follicular lymphoma (FL) is the second most common type of non-Hodgkin lymphoma (NHL). Histological transformation (HT) refers to the evolution of a clinically indolent NHL to a clinically aggressive one, defined as those lymphomas in which survival is limited to a few months when untreated. Areas covered: HT is associated with rapid progression of lymphadenopathy, infiltration of extranodal sites, development of systemic symptoms, and elevated serum level of lactate dehydrogenase (LDH). It is frequently related to a poor prognosis, and the median survival after transformation is less than 2 years. Transformation to diffuse large B cell lymphoma (DLBCL) in patients with FL occurs at an annual rate of approximately 3% for the first 15 years, after which the risk of HT falls for reasons that remain unclear. Expert commentary: Although it has long been assumed that transformation reflects the emergence of an aggressive subclone of cells from the primary FL, recent studies suggest that FL transformation might also arise by divergent evolution from a more immature common progenitor cell. Studies on genomic changes and DNA sequencing have shed some light onto the process of transformation. Nowadays, we know that HT is a complex process where several molecular pathways are involved.

Histological Transformation to Large Cell Neuroendocrine Carcinoma from Lung Adenocarcinoma Harboring an EGFR Mutation: An Autopsy Case Report

We herein report a 58-year-old Japanese woman who survived 14 years after surgery for lung adenocarcinoma harboring an epidermal growth factor receptor (EGFR) exon 19 deletion. She developed recurrence, for which she underwent multimodal therapy, including EGFR-tyrosine kinase inhibitor (TKI) administration. She ultimately died from a rapidly progressive right lung tumor that was resistant to EGFR-TKI. According to the autopsy findings, she had combined large-cell neuroendocrine carcinoma (LCNEC) and adenocarcinoma in the right lung, which retained an EGFR exon 19 deletion in both components. Therefore, the histological transformation to LCNEC can be a mechanism of acquired EGFR-TKI resistance.

Promoter methylation patterns in Richter syndrome affect stem-cell maintenance and cell cycle regulation and differ from de novo diffuse large B-cell lymphoma

In a fraction of patients, chronic lymphocytic leukaemia (CLL) can transform to Richter syndrome (RS), usually a diffuse large B-cell lymphoma (DLBCL). We studied genome-wide promoter DNA methylation in RS and clonally related CLL-phases of transformed patients, alongside de novo DLBCL (of non-germinal centre B type), untransformed-CLL and normal B-cells. The greatest differences in global DNA methylation levels were observed between RS and DLBCL, indicating that these two diseases, although histologically similar, are epigenetically distinct. RS was more highly methylated for genes involved in cell cycle regulation. When RS was compared to the preceding CLL-phase and with untransformed-CLL, RS presented a higher degree of methylation for genes possessing the H3K27me3 mark and PRC2 targets, as well as for gene targets of TP53 and RB1. Comparison of the methylation levels of individual genes revealed that OSM, a stem cell regulatory gene, exhibited significantly higher methylation levels in RS compared to CLL-phases. Its transcriptional repression by DNA methylation was confirmed by 5-aza-2'deoxycytidine treatment of DLBCL cells, determining an increased OSM expression. Our results showed that methylation patterns in RS are largely different from de novo DLBCL. Stem cell-related genes and cell cycle regulation genes are targets of DNA methylation in RS.