Chemoimmunotherapy resistant follicular lymphoma: predictors of resistance, association with transformation and prognosis

Identification of genetic subtypes in follicular lymphoma

Follicular lymphoma (FL) exhibits considerable variability in biological features and clinical trajectories across patients. To dissect the diversity of FL, we utilized a Bernoulli mixture model to identify genetic subtypes in 713 pre-treatment tumor tissue samples. Our analysis revealed the existence of five subtypes with unique genetic profiles that correlated with clinicopathological characteristics. The clusters were enriched in specific mutations as follows: CS (CREBBP and STAT6), TT (TNFAIP3 and TP53), GM (GNA13 and MEF2B), Q (quiescent, for low mutation burden), and AR (mutations of mTOR pathway-related genes). The subtype Q was enriched for patients with stage I disease and associated with a lower proliferative history than the other subtypes. The AR subtype was unique in its enrichment for IgM-expressing FL cases and was associated with advanced-stage and more than 4 nodal sites. The existence of subtypes was validated in an independent cohort of 418 samples from the GALLIUM trial. Notably, patients assigned to the TT subtype consistently experienced inferior progression-free survival when treated with immunochemotherapy. Our findings offer insight into core pathways distinctly linked with each FL cluster and are expected to be informative in the era of targeted therapies.

Early Progression of Follicular Lymphoma: Biology and Treatment

Follicular lymphoma is the most common subtype of indolent non-Hodgkin lymphoma. Although a majority of patients have a favorable prognosis, a subset of patients experiences early treatment failure. Progression of disease within 24 months of initial chemoimmunotherapy is associated with inferior survival. The biology of early progression is the subject of ongoing study and depends on the unique genetic composition of neoplastic cells and their interaction with a complex tumor microenvironment. Clinicogenetic prognostic indices have been developed to identify high-risk patients. Several have been validated but are limited in identifying those at risk for early treatment failure.

Response-adapted treatment with rituximab, bendamustine, mitoxantrone, and dexamethasone followed by rituximab maintenance in patients with relapsed or refractory follicular lymphoma after first-line immunochemotherapy: Results of the RBMDGELTAMO08 phase II trial

BACKGROUND

Consensus is lacking regarding the optimal salvage therapy for patients with follicular lymphoma who relapse after or are refractory to immunochemotherapy.

METHODS

This phase II trial evaluated the efficacy and safety of response-adapted therapy with rituximab, bendamustine, mitoxantrone, and dexamethasone (RBMD) in follicular lymphoma patients who relapsed after or were refractory to first-line immunochemotherapy. Sixty patients received three treatment cycles, and depending on their response received an additional one (complete/unconfirmed complete response) or three (partial response) cycles. Patients who responded to induction received rituximab maintenance therapy for 2 years.

RESULTS

Thirty-three (55%) and 42 (70%) patients achieved complete/unconfirmed complete response after three cycles and on completing induction therapy (4-6 cycles), respectively (final overall response rate, 88.3%). Median progression-free survival was 56.4 months (median follow-up, 28.3 months; 95% CI, 15.6-51.2). Overall survival was not reached. Progression-free survival did not differ between patients who received four vs six cycles (P = .6665), nor between patients who did/did not receive rituximab maintenance after first-line therapy (P = .5790). Median progression-free survival in the 10 refractory patients was 25.5 months (95% CI, 0.6-N/A) and was longer in patients who had shown progression of disease after 24 months of first-line therapy (median, 56.4 months; 95% CI, 19.8-56.4) than in those who showed early progression (median, 42.31 months; 95% CI, 24.41-NA) (P = .4258). Thirty-six (60%) patients had grade 3/4 neutropenia. Grade 3/4 febrile neutropenia and infection were recorded during induction (4/60 [6.7%] and 5/60 [8.3%] patients, respectively) and maintenance (2/43 [4.5%] and 4/43 [9.1%] patients, respectively).

CONCLUSIONS

This response-adapted treatment with RBMD followed by rituximab maintenance is an effective and well-tolerated salvage treatment for relapsed/refractory follicular lymphoma following first-line immunochemotherapy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov # NCT01133158.

Early progression after bendamustine-rituximab is associated with high risk of transformation in advanced stage follicular lymphoma

Despite widespread use of bendamustine and rituximab (BR) as frontline therapy for advanced-stage follicular lymphoma (FL), little is known about the risk of early progression or incidence of histological transformation. We performed a retrospective analysis of a population-based cohort of 296 patients with advanced-stage FL treated with frontline BR and maintenance rituximab. As previously demonstrated, outcomes with this regimen are excellent, with 2-year event-free survival estimated at 85% (95% confidence interval [95% CI], 80-89) and 2-year overall survival 92% (95% CI, 88-95). Progression of disease within 24 months (POD24) occurred in 13% of patients and was associated with a significantly inferior outcome with 2-year overall survival of 38% (95% CI, 20-55). The only significant risk factor for POD24 at baseline was elevated lactate dehydrogenase (P < .001). Importantly, the majority of POD24 patients (76%) had transformed disease. Compared with a historical cohort treated with rituximab, cyclophosphamide, vincristine, and prednisone, event-free survival has improved and the risk of POD24 has decreased, but a higher proportion of patients with POD24 harbor transformation. The overall incidence of transformation appears unchanged. The presence of occult or early transformation is the main driver of POD24 in FL patients treated with frontline BR. Identification of biomarkers and improved management strategies for transformation will be crucial to improving outcomes.

Transformation of follicular lymphoma to double-hit lymphoma during adjuvant chemotherapy for concurrent ovarian carcinoma

The frequency of multiple primary malignant neoplasms (MPMN) is increasing due to population aging. Since consensus guidelines for the treatment of MPMN are lacking, treatment strategies are determined by disease status on a per-patient basis. In this report, we describe a case of MPMN with follicular lymphoma (FL) grade 1 that transformed to double-hit lymphoma during adjuvant chemotherapy for concurrent ovarian carcinoma. A 64-year-old woman was diagnosed with MPMN of FL and endometrioid carcinoma by staging laparotomy and lymph node biopsy. She received four cycles of adjuvant chemotherapy (carboplatin and paclitaxel) for endometrioid carcinoma, but during chemotherapy, the FL grade 1 transformed to double-hit lymphoma. We speculate that adjuvant chemotherapy for endometrioid carcinoma may have triggered the transformation of FL in the present case.

Surrogate Endpoints and Risk Adaptive Strategies in Previously Untreated Follicular Lymphoma

Follicular lymphoma is the second most common subtype of non-Hodgkin lymphoma with an estimated 3.18 cases per 100,000 people. Despite the prolongation of survival with chemoimmunotherapy, variability in response to initial treatment and outcome still exists. Whereas prolonging overall survival is important, it is generally an unreasonable primary endpoint in the front-line setting. The long follow-up needed and the influence of subsequent therapies creates a potential bias. Thus, clinical trials require approximately 5 to 8 years from activation to completion and analysis of outcomes. This duration results in enormous cost and a delay in developing newer therapies. Thus, there is a need to identify markers or surrogate endpoints that can be used in clinical trials to expedite the development of new treatments. This review will discuss various clinical, radiologic, and laboratory measures used to assess outcomes and overall survival in patients with untreated follicular lymphoma, and gauge their utility in clinical trials as surrogate endpoints.

From genetics to the clinic: a translational perspective on follicular lymphoma

Follicular lymphoma (FL) is the most frequent indolent B cell lymphoma and is still considered to be incurable. In recent years, whole-exome sequencing studies of large cohorts of patients have greatly improved our knowledge of the FL mutational landscape. Moreover, the prolonged evolution of this disease has enabled some insights regarding the early pre-lymphoma lesions as well as the clonal evolution after treatment, allowing an evolutionary perspective on lymphomagenesis. Deciphering the earliest initiating lesions and identifying the molecular alterations leading to disease progression currently represent important goals; accomplishing these could help identify the most relevant targets for precision therapy.

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.

Pathogenesis of follicular lymphoma

Follicular lymphoma (FL) is presented as a germinal centre B cell lymphoma that is characterized by an indolent clinical course, but remains - paradoxically - largely incurable to date. The last years have seen significant progress in our understanding of FL lymphomagenesis, which is a multi-step process beginning in the bone marrow with the hallmark t(14;18)(q32;q21) translocation. The pathobiology of FL is complex and combines broad somatic changes at the level of both the genome and the epigenome, the latter evidenced by highly recurrent mutations in chromatin-modifying genes such as KMT2D and CREBBP. While the importance of the FL microenvironment has since long been well understood, it has become evident that somatic lesions within tumour cells re-educate normal immune and stromal cells to their advantage. Enhanced understanding of FL pathogenesis is currently leading to refined therapeutic targeting of perturbed biology, paving the way for precision medicine in this lymphoma subtype.

Transformed follicular lymphoma

Follicular Lymphoma (FL) is the second most common type of non-Hodgkin lymphoma and is considered to be the prototype of indolent lymphomas. Histologic transformation into an aggressive lymphoma, which is expected to occur at a rate of 2 to 3% each year, is associated with rapid progression, treatment resistance, and poor prognosis. Recent modifications to the physiopathologic mechanism of transformed follicular lymphoma (t-FL) have been proposed, including genetic and epigenetic mechanisms as well as a role for the microenvironment. Although t-FL is considered a devastating complication, as it is associated with treatment-refractory disease and a dismal outcome, recent data in the rituximab era have suggested that not only is the prognosis less severe than reported in the previous literature but the risk of transformation is also lower. Thus, this study aimed to review the most recent research on t-FL in an attempt to better understand the clinical meaning of transformation from FL to diffuse large B cell lymphoma (DLBCL) and the impact of current treatment strategies on the curability of this intriguing subentity of lymphoma.

Current prognostic and predictive factors in follicular lymphoma

Follicular lymphoma (FL) is generally considered an indolent disorder. With modern day treatments, long remissions are often achieved both in the front-line and relapsed setting. However, a subset of patients has a more aggressive course and a worse outcome. Their identification is the main purpose of modern day prognostic tools. In this review, we attempt to summarize the evidence concerning prognostic and predictive factors in FL, including (1) pre-treatment factors, from baseline clinical characteristics and imaging tests to histological grade, the microenvironment and genomic abnormalities; (2) post-treatment factors, i.e., depth of response, measured both by imaging tests and minimal residual disease; (3) factors at relapse and duration of response; and (4) prognostic factors in histological transformation. We conclude that, despite the existence of numerous tools, the availability of some of them is still limited; they generally suffer from notable downsides, and most have unproven predictive value, thus having scarce bearing on the choice of regimen at present. However, with the technological and scientific developments of the last few years, the potential for these prognostic factors is promising, particularly in combination, which will probably, in time, help guide therapeutic decisions.

Can histologic transformation of follicular lymphoma be predicted and prevented?

Transformation to aggressive lymphoma is a critical event in the clinical course of follicular lymphoma (FL) patients. Yet, it is a challenge to reliably predict transformation at the time of diagnosis. Understanding the risk of transformation would be useful for guiding and monitoring patients, as well as for evaluating novel treatment strategies that could potentially prevent transformation. Herein, we review the contribution of clinical, pathological, and genetic risk factors to transformation. Patients with multiple clinical high-risk factors are at elevated risk of transformation but we are currently lacking a prognostic index that would specifically address transformation rather than disease progression or overall survival. From the biological standpoint, multiple studies have correlated individual biomarkers with transformation. However, accurate prediction of this event is currently hampered by our limited knowledge of the evolutionary pathways leading to transformation, as well as the scarcity of comprehensive, large-scale studies that assess both the genomic landscape of alterations within tumor cells and the composition of the microenvironment. Liquid biopsies hold great promise for achieving precision medicine. Indeed, mutations detected within circulating tumor DNA may be a better reflection of the inherent intratumoral heterogeneity than the biopsy of a single site. Last, we will assess whether evidence exists in the literature that transformation might be prevented altogether, based on the choice of therapy for FL.

The relationship of REL proto-oncogene to pathobiology and chemoresistance in follicular and transformed follicular lymphoma

Follicular lymphoma (FL) is a common type of indolent lymphoma that occasionally transforms to more aggressive B-cell lymphomas. These transformed follicular lymphomas (tFL) are often associated with chemoresistance whose mechanisms are currently unknown. REL, a proto-oncogene located on frequently amplified 2p16.1-p15 locus, promotes tumorigenesis in many cancer types through deregulation of the NF-κB pathway; however, its role in FL pathobiology or chemoresistance has not been addressed. Here, we evaluated REL gene copy number by q-PCR on FFPE FL tumor samples, and observed REL amplification in 30.4% of FL cases that was associated with weak elevation of transcript levels. PCR-Sanger analysis did not show any somatic mutation in FL tumors. In support of a marginal oncogenic role, a REL-transduced FL cell line was positively selected under limiting serum conditions. Interestingly, reanalysis of previously reported gene expression profiles revealed significant enrichment of DNA damage-induced repair and cell cycle arrest pathways in tFL tumors with high REL expression compared to those with low REL expression consistent with the critical role of c-REL in genotoxicity-induced NF-κB signaling, which was reported to lead to drug resistance. In addition to DNA damage repair genes such as ATM and BRCA1, anti-apoptotic BCL2 was significantly elevated in REL-high FL and tFL tumors. Altogether these data suggest that other genes located in amplified 2p16.1-p15 locus may have more oncogenic role in FL etiology; however, high REL expression may be useful as a predictive biomarker of response to immunochemotherapy, and inhibition of c-REL may potentially sensitize resistant FL or tFL cells to chemotherapy.

Histological Transformation and Progression in Follicular Lymphoma: A Clonal Evolution Study

BACKGROUND

Follicular lymphoma (FL) is an indolent, yet incurable B cell malignancy. A subset of patients experience an increased mortality rate driven by two distinct clinical end points: histological transformation and early progression after immunochemotherapy. The nature of tumor clonal dynamics leading to these clinical end points is poorly understood, and previously determined genetic alterations do not explain the majority of transformed cases or accurately predict early progressive disease. We contend that detailed knowledge of the expansion patterns of specific cell populations plus their associated mutations would provide insight into therapeutic strategies and disease biology over the time course of FL clinical histories.

METHODS AND FINDINGS

Using a combination of whole genome sequencing, targeted deep sequencing, and digital droplet PCR on matched diagnostic and relapse specimens, we deciphered the constituent clonal populations in 15 transformation cases and 6 progression cases, and measured the change in clonal population abundance over time. We observed widely divergent patterns of clonal dynamics in transformed cases relative to progressed cases. Transformation specimens were generally composed of clones that were rare or absent in diagnostic specimens, consistent with dramatic clonal expansions that came to dominate the transformation specimens. This pattern was independent of time to transformation and treatment modality. By contrast, early progression specimens were composed of clones that were already present in the diagnostic specimens and exhibited only moderate clonal dynamics, even in the presence of immunochemotherapy. Analysis of somatic mutations impacting 94 genes was undertaken in an extension cohort consisting of 395 samples from 277 patients in order to decipher disrupted biology in the two clinical end points. We found 12 genes that were more commonly mutated in transformed samples than in the preceding FL tumors, including TP53, B2M, CCND3, GNA13, S1PR2, and P2RY8. Moreover, ten genes were more commonly mutated in diagnostic specimens of patients with early progression, including TP53, BTG1, MKI67, and XBP1.

CONCLUSIONS

Our results illuminate contrasting modes of evolution shaping the clinical histories of transformation and progression. They have implications for interpretation of evolutionary dynamics in the context of treatment-induced selective pressures, and indicate that transformation and progression will require different clinical management strategies.

Clinicogenetic risk models predict early progression of follicular lymphoma after first-line immunochemotherapy

Follicular lymphoma (FL) is a clinically and molecularly heterogeneous disease. Posttreatment surrogate end points, such as progression of disease within 24 months (POD24) are promising predictors for overall survival (OS) but are of limited clinical value, primarily because they cannot guide up-front treatment decisions. We used the clinical and molecular data from 2 independent cohorts of symptomatic patients in need of first-line immunochemotherapy (151 patients from a German Low-Grade Lymphoma Study Group [GLSG] trial and 107 patients from a population-based registry of the British Columbia Cancer Agency [BCCA]) to validate the predictive utility of POD24, and to evaluate the ability of pretreatment risk models to predict early treatment failure. POD24 occurred in 17% and 23% of evaluable GLSG and BCCA patients, with 5-year OS rates of 41% (vs 91% for those without POD24, P < .0001) and 26% (vs 86%, P < .0001), respectively. The m7-FL International Prognostic Index (m7-FLIPI), a prospective clinicogenetic risk model for failure-free survival, had the highest accuracy to predict POD24 (76% and 77%, respectively) with an odds ratio of 5.82 in GLSG (P = .00031) and 4.76 in BCCA patients (P = .0052). A clinicogenetic risk model specifically designed to predict POD24, the POD24-PI, had the highest sensitivity to predict POD24, but at the expense of a lower specificity. In conclusion, the m7-FLIPI prospectively identifies the smallest subgroup of patients (28% and 22%, respectively) at highest risk of early failure of first-line immunochemotherapy and death, including patients not fulfilling the POD24 criteria, and should be evaluated in prospective trials of precision medicine approaches in FL.

The role of autologous and allogeneic stem cell transplantation in the management of indolent B-cell lymphoma

Despite improvements over the past decade in the overall survival of patients with indolent non-Hodgkin lymphomas, these lymphomas remain largely incurable with standard therapies. Immunochemotherapy with rituximab-based regimens has become a well-established standard of care in the primary and relapsed disease settings. The role of hematopoietic stem cell transplantation in indolent lymphoma has been defined by the adoption of this therapy largely in the relapse setting because randomized trials in the first-line setting have not shown survival advantages. Allogeneic stem cell transplantation has the possibility for cure because of the potential for immunologic graft-versus-lymphoma effect, but there are significant concerns regarding nonrelapse mortality. Autologous stem cell transplantation offers a safe treatment platform, but relapse remains a significant issue. The role of transplantation in the current treatment landscape of immunochemotherapy has not been conclusively proven, and randomized trials are lacking. This review summarizes the current relevant data regarding transplantation in indolent non-Hodgkin lymphoma and highlights the issues relevant to clinicians in the field.

Factors influencing outcome in advanced stage, low-grade follicular lymphoma treated at MD Anderson Cancer Center in the rituximab era

BACKGROUND

The optimal initial therapy of follicular lymphoma (FL) remains unclear. The aims of this study were to compare primary treatment strategies and assess the impact of maintenance rituximab and patterns of treatment failure.

PATIENTS AND METHODS

We retrospectively analyzed patients with treatment-naive advanced stage, grade 1-2 FL treated at our center from 2004 to 2014. We included 356 patients treated on clinical trials or standard of care with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP, n = 119); R-CHOP with maintenance (R-CHOP + M, n = 65); bendamustine/rituximab (BR, n = 45); BR with maintenance (BR + M, n = 35); R(2) (n = 94). We compared baseline characteristics, progression-free survival (PFS), overall survival (OS) and analyzed prognostic factors using univariate and multivariate analysis adjusted for treatment.

RESULTS

After a median follow-up of 4 years (range 0.2-15.0), the 3-year PFS was 60% [95% confidence interval (CI) 51% to 69%] for R-CHOP, 72% (59% to 82%) for R-CHOP + M, 63% (42% to 78%) for BR, 97% (80% to 100%) for BR + M and 87% (78% to 93%) for R(2). Patients treated with R-chemotherapy had more high-risk features than patients treated with R(2) but, by adjusted multivariate analysis, treatment with R(2) [hazard ratio (HR) 0.39 (0.17-0.89), P = 0.02] was associated with a superior PFS. Eastern Cooperative Oncology Group Performance status of one or more predicted inferior OS. Among patients treated with R-chemotherapy, maintenance was associated with the superior PFS [HR 0.38 (95% CI 0.21-0.68)]. By adjusted multivariate analysis, disease progression within 2 years [HR 5.1 (95% CI 1.57-16.83)] and histologic transformation (HT) [HR 11.05 (95% CI 2.84-42.93)] increased risk of death.

CONCLUSION

Induction therapy with R(2) may result in disease control which is comparable with R-chemotherapy. Early disease progression and HT are predictive of inferior survival.

Reduced-Intensity Allografting as First Transplantation Approach in Relapsed/Refractory Grades One and Two Follicular Lymphoma Provides Improved Outcomes in Long-Term Survivors

This study was conducted to compare long-term outcomes in patients with refractory/relapsed grades 1 and 2 follicular lymphoma (FL) after allogeneic (allo) versus autologous (auto) hematopoietic cell transplantation (HCT) in the rituximab era. Adult patients with relapsed/refractory grades 1 and 2 FL undergoing first reduced-intensity allo-HCT or first autograft during 2000 to 2012 were evaluated. A total of 518 rituximab-treated patients were included. Allo-HCT patients were younger and more heavily pretreated, and more patients had advanced stage and chemoresistant disease. The 5-year adjusted probabilities, comparing auto-HCT versus allo-HCT groups for nonrelapse mortality (NRM) were 5% versus 26% (P < .0001); relapse/progression: 54% versus 20% (P < .0001); progression-free survival (PFS): 41% versus 58% (P < .001), and overall survival (OS): 74% versus 66% (P = .05). Auto-HCT was associated with a higher risk of relapse/progression beyond 5 months after HCT (relative risk [RR], 4.4; P < .0001) and worse PFS (RR, 2.9; P < .0001) beyond 11 months after HCT. In the first 24 months after HCT, auto-HCT was associated with improved OS (RR, .41; P < .0001), but beyond 24 months, it was associated with inferior OS (RR, 2.2; P = .006). A landmark analysis of patients alive and progression-free at 2 years after HCT confirmed these observations, showing no difference in further NRM between both groups, but there was significantly higher risk of relapse/progression (RR, 7.3; P < .0001) and inferior PFS (RR, 3.2; P < .0001) and OS (RR, 2.1; P = .04) after auto-HCT. The 10-year cumulative incidences of second hematological malignancies after allo-HCT and auto-HCT were 0% and 7%, respectively. Auto-HCT and reduced-intensity-conditioned allo-HCT as first transplantation approach can provide durable disease control in grades 1 and 2 FL patients. Continued disease relapse risk after auto-HCT translates into improved PFS and OS after allo-HCT in long-term survivors.