Outcomes of limited stage primary bone diffuse large B-cell lymphoma in the rituximab era: a multicenter, retrospective study

Primary bone diffuse large B-cell lymphoma is a rare variant of extranodal non-Hodgkin lymphoma historically treated with induction chemotherapy followed by consolidative radiation therapy (RT). It remains unknown whether RT confers additional benefit following rituximab-based chemoimmunotherapy (CIT) induction in patients with limited stage disease. We conducted a multicenter, retrospective analysis of patients treated between 2005 and 2019 using rituximab-based CIT regimens with or without consolidative RT to discern whether consolidative RT adds benefit in patients with stage I-II disease that could be encompassed in one radiation field. A total of 112 patients were included: 78 received CIT and radiation (RT group), and 34 received CIT alone (no RT group). The overall survival at 10 years was 77.9% in the RT group and 89.0% in the no RT group (P=0.42). The relapse-free survival at 10 years was 73.5% in the RT group and 80.3% in the no RT group (P=0.88). Neither improved overall survival nor relapse-free survival was associated with the addition of consolidative RT. Subgroup analysis of patients only achieving a partial response after CIT suggests that these patients may benefit from consolidative RT.

Tumor-Infiltrating Normal B Cells Revealed by Immunoglobulin Repertoire Clonotype Analysis Are Highly Prognostic and Crucial for Antitumor Immune Responses in DLBCL

PURPOSE

Tumor-infiltrating B lymphocytes (TIL-B) have demonstrated prognostic and predictive significance in solid cancers. In this study, we aimed to distinguish TIL-Bs from malignant B-cells in diffuse large B-cell lymphoma (DLBCL) and determine the clinical and biological significance.

EXPERIMENTAL DESIGN

A total of 269 patients with de novo DLBCL from the International DLBCL R-CHOP Consortium Program were studied. Ultra-deep sequencing of the immunoglobulin genes was performed to determine B-cell clonotypes. The frequencies and numbers of TIL-B clonotypes in individual repertoires were correlated with patient survival, gene expression profiling (GEP) data, and frequencies of DLBCL-infiltrating immune cells quantified by fluorescent multiplex IHC at single-cell resolution.

RESULTS

TIL-B abundance, evaluated by frequencies of normal B-cell clonotypes in the immunoglobulin repertoires, remarkably showed positive associations with significantly better survival of patients in our sequenced cohorts. DLBCLs with high versus low TIL-B abundance displayed distinct GEP signatures, increased pre-memory B-cell state and naïve CD4 T-cell state fractions, and higher CD4+ T-cell infiltration. TIL-B frequency, as a new biomarker in DLBCL, outperformed the germinal center (GC) B-cell-like/activated B-cell-like classification and TIL-T frequency. The identified TIL-B-high GEP signature, including genes upregulated during T-dependent B-cell activation and those highly expressed in normal GC B cells and T cells, showed significant favorable prognostic effects in several external validation cohorts.

CONCLUSIONS

TIL-B frequency is a significant prognostic factor in DLBCL and plays a crucial role in antitumor immune responses. This study provides novel insights into the prognostic determinants in DLBCL and TIL-B functions with important therapeutic implications.

Validation of Immunotherapy Response Score as Predictive of Pan-solid Tumor Anti-PD-1/PD-L1 Benefit

Immunotherapy response score (IRS) integrates tumor mutation burden (TMB) and quantitative expression biomarkers to predict anti-PD-1/PD-L1 [PD-(L)1] monotherapy benefit. Here, we evaluated IRS in additional cohorts. Patients from an observational trial (NCT03061305) treated with anti-PD-(L)1 monotherapy were included and assigned to IRS-High (-H) versus -Low (-L) groups. Associations with real-world progression-free survival (rwPFS) and overall survival (OS) were determined by Cox proportional hazards (CPH) modeling. Those with available PD-L1 IHC treated with anti-PD-(L)1 with or without chemotherapy were separately assessed. Patients treated with PD-(L)1 and/or chemotherapy (five relevant tumor types) were assigned to three IRS groups [IRS-L divided into IRS-Ultra-Low (-UL) and Intermediate-Low (-IL), and similarly assessed]. In the 352 patient anti-PD-(L)1 monotherapy validation cohort (31 tumor types), IRS-H versus IRS-L patients had significantly longer rwPFS and OS. IRS significantly improved CPH associations with rwPFS and OS beyond microsatellite instability (MSI)/TMB alone. In a 189 patient (10 tumor types) PD-L1 IHC comparison cohort, IRS, but not PD-L1 IHC nor TMB, was significantly associated with anti-PD-L1 rwPFS. In a 1,103-patient cohort (from five relevant tumor types), rwPFS did not significantly differ in IRS-UL patients treated with chemotherapy versus chemotherapy plus anti-PD-(L)1, nor in IRS-H patients treated with anti-PD-(L)1 versus anti-PD-(L)1 + chemotherapy. IRS associations were consistent across subgroups, including both Europeans and non-Europeans. These results confirm the utility of IRS utility for predicting pan-solid tumor PD-(L)1 monotherapy benefit beyond available biomarkers and demonstrate utility for informing on anti-PD-(L)1 and/or chemotherapy treatment.

Significance

This study confirms the utility of the integrative IRS biomarker for predicting anti-PD-L1/PD-1 benefit. IRS significantly improved upon currently available biomarkers, including PD-L1 IHC, TMB, and MSI status. Additional utility for informing on chemotherapy, anti-PD-L1/PD-1, and anti-PD-L1/PD-1 plus chemotherapy treatments decisions is shown.

Determining clinical course of diffuse large B-cell lymphoma using targeted transcriptome and machine learning algorithms

Multiple studies have demonstrated that diffuse large B-cell lymphoma (DLBCL) can be divided into subgroups based on their biology; however, these biological subgroups overlap clinically. Using machine learning, we developed an approach to stratify patients with DLBCL into four subgroups based on survival characteristics. This approach uses data from the targeted transcriptome to predict these survival subgroups. Using the expression levels of 180 genes, our model reliably predicted the four survival subgroups and was validated using independent groups of patients. Multivariate analysis showed that this patient stratification strategy encompasses various biological characteristics of DLBCL, and only TP53 mutations remained an independent prognostic biomarker. This novel approach for stratifying patients with DLBCL, based on the clinical outcome of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone therapy, can be used to identify patients who may not respond well to these types of therapy, but would otherwise benefit from alternative therapy and clinical trials.

Genetic Subtyping and Phenotypic Characterization of the Immune Microenvironment and MYC/BCL2 Double Expression Reveal Heterogeneity in Diffuse Large B-cell Lymphoma

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) is molecularly and clinically heterogeneous, and can be subtyped according to genetic alterations, cell-of-origin, or microenvironmental signatures using high-throughput genomic data at the DNA or RNA level. Although high-throughput proteomic profiling has not been available for DLBCL subtyping, MYC/BCL2 protein double expression (DE) is an established prognostic biomarker in DLBCL. The purpose of this study is to reveal the relative prognostic roles of DLBCL genetic, phenotypic, and microenvironmental biomarkers.

EXPERIMENTAL DESIGN

We performed targeted next-generation sequencing; IHC for MYC, BCL2, and FN1; and fluorescent multiplex IHC for microenvironmental markers in a large cohort of DLBCL. We performed correlative and prognostic analyses within and across DLBCL genetic subtypes and MYC/BCL2 double expressors.

RESULTS

We found that MYC/BCL2 double-high-expression (DhE) had significant adverse prognostic impact within the EZB genetic subtype and LymphGen-unclassified DLBCL cases but not within MCD and ST2 genetic subtypes. Conversely, KMT2D mutations significantly stratified DhE but not non-DhE DLBCL. T-cell infiltration showed favorable prognostic effects within BN2, MCD, and DhE but unfavorable effects within ST2 and LymphGen-unclassified cases. FN1 and PD-1-high expression had significant adverse prognostic effects within multiple DLBCL genetic/phenotypic subgroups. The prognostic effects of DhE and immune biomarkers within DLBCL genetic subtypes were independent although DhE and high Ki-67 were significantly associated with lower T-cell infiltration in LymphGen-unclassified cases.

CONCLUSIONS

Together, these results demonstrated independent and additive prognostic effects of phenotypic MYC/BCL2 and microenvironment biomarkers and genetic subtyping in DLBCL prognostication, important for improving DLBCL classification and identifying prognostic determinants and therapeutic targets.

Real-World Performance of a Comprehensive Genomic Profiling Test Optimized for Small Tumor Samples

PURPOSE

Tissue-based comprehensive genomic profiling (CGP) is increasingly used for treatment selection in patients with advanced cancer; however, tissue availability may limit widespread implementation. Here, we established real-world CGP tissue availability and assessed CGP performance on consecutively received samples.

MATERIALS AND METHODS

We conducted a post hoc, nonprespecified analysis of 32,048 consecutive tumor tissue samples received for StrataNGS, a multiplex polymerase chain reaction (PCR)-based comprehensive genomic profiling (PCR-CGP) test, as part of an ongoing observational trial (NCT03061305). Sample characteristics and PCR-CGP performance were assessed across all tested samples, including exception samples not meeting minimum input quality control (QC) requirements (< 20% tumor content [TC], < 2 mm2 tumor surface area [TSA], DNA or RNA yield < 1 ng/µL, or specimen age > 5 years). Tests reporting ≥ 1 prioritized alteration or meeting TC and sequencing QC were considered successful. For prostate carcinoma and lung adenocarcinoma, tests reporting ≥ 1 actionable or informative alteration or meeting TC and sequencing QC were considered actionable.

RESULTS

Among 31,165 (97.2%) samples where PCR-CGP was attempted, 10.7% had < 20% TC and 59.2% were small (< 25 mm2 tumor surface area). Of 31,101 samples evaluable for input requirements, 8,089 (26.0%) were exceptions not meeting requirements. However, 94.2% of the 31,101 tested samples were successfully reported, including 80.5% of exception samples. Positive predictive value of PCR-CGP for ERBB2 amplification in exceptions and/or sequencing QC-failure breast cancer samples was 96.7%. Importantly, 84.0% of tested prostate carcinomas and 87.9% of lung adenocarcinomas yielded results informing treatment selection.

CONCLUSION

Most real-world tissue samples from patients with advanced cancer desiring CGP are limited, requiring optimized CGP approaches to produce meaningful results. An optimized PCR-CGP test, coupled with an inclusive exception testing policy, delivered reportable results for > 94% of samples, potentially expanding the proportion of CGP-testable patients and impact of biomarker-guided therapies.

Genomic complexity is associated with epigenetic regulator mutations and poor prognosis in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma with high mutation burdens but a low response rate to immune checkpoint inhibitors. In this study, we performed targeted next-generation sequencing and fluorescent multiplex immunohistochemistry, and investigated the clinical significance and immunological effect of mutation numbers in 424 DLBCL patients treated with standard immunochemotherapy. We found that KMT2D and TP53 nonsynonymous mutations (MUT) were significantly associated with increased nonsynonymous mutation numbers, and that high mutation numbers (MUT^high) were associated with significantly poorer clinical outcome in germinal center B-cell-like DLBCL with wild-type TP53. To understand the underlying mechanisms, we identified a gene-expression profiling signature and the association of MUT^high with decreased T cells in DLBCL patients with wild-type TP53. On the other hand, in overall cohort, MUT^high was associated with lower PD-1 expression in T cells and PD-L1 expression in macrophages, suggesting a positive role of MUT^high in immune responses. Analysis in a whole-exome sequencing dataset of 304 patients deposited by Chapuy et al. validated the correlation of MUT-KMT2D with genomic complexity and the significantly poorer survival associated with higher numbers of genomic single nucleotide variants in activated B-cell-like DLBCL with wild-type TP53. Together, these results suggest that KMT2D inactivation or epigenetic dysregulation has a role in driving DLBCL genomic instability, and that genomic complexity has adverse impact on clinical outcome in DLBCL patients with wild-type TP53 treated with standard immunochemotherapy. The oncoimmune data in this study have important implications for biomarker and therapeutic studies in DLBCL.

Aggressive B-cell Lymphoma with MYC/TP53 Dual Alterations Displays Distinct Clinicopathobiological Features and Response to Novel Targeted Agents

Diffuse large B-cell lymphoma (DLBCL) is the major type of aggressive B-cell lymphoma. High-grade B-cell lymphoma (HGBCL) with MYC/BCL2 double-hit (DH) represents a distinct entity with dismal prognosis after standard immunochemotherapy in the current WHO lymphoma classification. However, whether TP53 mutation synergizes with MYC abnormalities (MYC rearrangement and/or Myc protein overexpression) contributing to HGBCL-like biology and prognosis is not well investigated. In this study, patients with DLBCL with MYC/TP53 abnormalities demonstrated poor clinical outcome, high-grade morphology, and distinct gene expression signatures. To identify more effective therapies for this distinctive DLBCL subset, novel MYC/TP53/BCL-2-targeted agents were investigated in DLBCL cells with MYC/TP53 dual alterations or HGBCL-MYC/BCL2-DH. A BET inhibitor INCB057643 effectively inhibited cell viability and induced apoptosis in DLBCL/HGBCL cells regardless of MYC/BCL2/TP53 status. Combining INCB057643 with a MDM2-p53 inhibitor DS3032b significantly enhanced the cytotoxic effects in HGBCL-DH without TP53 mutation, while combining with the BCL-2 inhibitor venetoclax displayed potent therapeutic synergy in DLBCL/HGBCL cells with and without concurrent TP53 mutation. Reverse-phase protein arrays revealed the synergistic molecular actions by INCB057643, DS3032b and venetoclax to induce cell-cycle arrest and apoptosis and to inhibit AKT/MEK/ERK/mTOR pathways, as well as potential drug resistance mechanisms mediated by upregulation of Mcl-1 and RAS/RAF/MEK/ERK pathways. In summary, these findings support subclassification of DLBCL/HGBCL with dual MYC/TP53 alterations, which demonstrates distinct pathobiologic features and dismal survival with standard therapy, therefore requiring additional targeted therapies. IMPLICATIONS: The clinical and pharmacologic studies suggest recognizing DLBCL with concomitant TP53 mutation and MYC abnormalities as a distinctive entity necessary for precision oncology practice. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/2/249/F1.large.jpg.

XPO1 expression worsens the prognosis of unfavorable DLBCL that can be effectively targeted by selinexor in the absence of mutant p53

The XPO1 inhibitor selinexor was recently approved in relapsed/refractory DLBCL patients but only demonstrated modest anti-DLBCL efficacy, prompting us to investigate the prognostic effect of XPO1 in DLBCL patients and the rational combination therapies in high-risk DLBCL. High XPO1 expression (XPO1high) showed significant adverse prognostic impact in 544 studied DLBCL patients, especially in those with BCL2 overexpression. Therapeutic study in 30 DLBCL cell lines with various molecular and genetic background found robust cytotoxicity of selinexor, especially in cells with BCL2-rearranged (BCL2-R+) DLBCL or high-grade B-cell lymphoma with MYC/BCL2 double-hit (HGBCL-DH). However, expression of mutant (Mut) p53 significantly reduced the cytotoxicity of selinexor in overall cell lines and the BCL2-R and HGBCL-DH subsets, consistent with the favorable impact of XPO1high observed in Mut-p53-expressing patients. The therapeutic effect of selinexor in HGBCL-DH cells was significantly enhanced when combined with a BET inhibitor INCB057643, overcoming the drug resistance in Mut-p53-expressing cells. Collectively, these data suggest that XPO1 worsens the survival of DLBCL patients with unfavorable prognostic factors such as BCL2 overexpression and double-hit, in line with the higher efficacy of selinexor demonstrated in BCL2-R+ DLBCL and HGBCL-DH cell lines. Expression of Mut-p53 confers resistance to selinexor treatment, which can be overcome by combined INCB057643 treatment in HGBCL-DH cells. This study provides insight into the XPO1 significance and selinexor efficacy in DLBCL, important for developing combination therapy for relapsed/refractory DLBCL and HGBCL-DH.

External Validation of AJCC Eighth Edition of Non-small-cell Lung Cancer Staging Among African Americans

INTRODUCTION

The American Joint Committee on Cancer (AJCC) eighth staging classification system for non-small-cell lung cancer was based on data from a multinational study consisting of 94,708 patients. African Americans were not included in this large database.

MATERIALS AND METHODS

The authors aimed to compare the performance of the AJCC eighth staging system with that of the seventh in predicting overall survival among African Americans utilizing the National Cancer Database. Cases with T- and M- categories were classified into 2 groups based on the AJCC seventh and eighth edition staging systems. Kaplan-Meier curves for overall survival were then constructed for each subgroup. Concordance index was computed using Uno's methodology to assess the overall performance between the 2 staging systems in predicting the mortality. Time-dependent area under the curve was calculated at each follow-up event for the seventh and eighth edition clinical and pathologic staging using an inverse probability of censoring weighted methodology. A 2-sided P-value < .05 was considered to show statistical significance.

RESULTS

The database identified a total of 70,606 African American patients in the study period of 2004 through 2014. Area under the curve values were consistently higher for the eighth edition scheme compared with the seventh edition (concordance 0.630 vs. 0.624, respectively; P < .0001 for clinical staging scheme and 0.596 vs. 0.591, respectively; P = .01 for pathologic staging scheme).

CONCLUSION

The AJCC eighth edition staging system showed better prognostic value in predicting overall survival when compared with the AJCC seventh edition staging scheme among African American patients with non-small-cell lung cancer.

Acquisition of Cabozantinib-Sensitive MET D1228N Mutation During Progression on Crizotinib in MET-Amplified Triple-Negative Breast Cancer

BACKGROUND

Targeting of somatic MET mutations using crizotinib has led to strong clinical responses, most frequently in patients with lung cancer, raising the possibility of adopting similar treatment strategies in patients with MET alterations in other cancer types.

PATIENT AND METHODS

We describe a patient with advanced triple-negative breast cancer with a 30-fold amplification of MET. Next-generation sequencing of pre- and postprogression biopsies was performed to identify the resistance mechanism emerging after an initial exceptional response to crizotinib. The response of the resistance mutant to type I and II MET inhibitors was assessed in cultured cells.

RESULTS

After progressing on crizotinib, a MET-D1228N mutation was detected, which is located in the crizotinib-binding region of the MET kinase domain. Experimental studies demonstrated that this mutation confers complete resistance to crizotinib yet retains cabozantinib sensitivity. Treatment of the patient with cabozantinib led to a subjective improvement in clinical symptoms, but the patient progressed after 7 weeks.

CONCLUSION

Although MET mutations are rare in breast cancer, these patients may experience substantial clinical benefit from crizotinib treatment. Nevertheless, drug resistance owing to on-target MET mutations will likely be frequently encountered and comprehensive mechanistic studies to assess sensitivity of these mutants to a series of potential second-line therapies may help guide subsequent treatment for these patients.

Abstract 1317: Exceptional responses to crizotinib in breast cancer patients with somatic MET and ROS1 alterations

Crizotinib is FDA approved in lung cancers with alterations in MET, ROS1 or ALK. Alterations in these genes are also reported in breast cancer, but are very rare and not routinely evaluated. Here we describe two heavily pre-treated patients with metastatic breast cancer treated with off-label single-agent crizotinib following NGS panel detection of alterations in MET and ROS1 in their tumors. Both patients had strong responses to crizotinib. Patient I was a stage IV triple-negative breast cancer patient in her early forties, previously treated with doxorubicin/cyclophosphamide, carboplatin/paclitaxel and with capecitabine. PET/CT imaging after progression on capecitabine revealed extensive metastatic disease. A NGS assay detected a 30-fold amplification of MET. MET amplification, overexpression and hyperactivity was confirmed by FISH and by IHC for total MET and phospho-MET, respectively. Single agent crizotinib (250 mg, twice daily) was well-tolerated. Immunostaining of a biopsy taken after 9 days of treatment showed elimination of active phosphorylated MET, demonstrating in-tumor crizotinib efficacy at the clinical dose. CT imaging at 10 weeks showed a resolution of her metastatic disease, meeting RECIST 1.1 criteria for a complete response. This response was sustained at 22 weeks. At 37 weeks, the patient progressed in the pleura. An ultrasound guided biopsy revealed a robust resurgence of MET phosphorylation while still taking crizotinib, suggesting an alteration rendering MET recalcitrant to crizotinib. NGS revealed a MET D1228N mutation, previously reported in crizotinib resistant lung cancer. This mutation was not detected in the pre-crizotinib biopsy (locus sequenced at 6300x) suggesting de novo acquisition in response to crizotinib. Mechanistic studies in HEK393 cells indicated that this mutation is sufficient to confer crizotinib (Type I MET inhibitor) resistance but remains sensitive to cabozantinib (Type II MET inhibitor). Transition to cabozantinib (initially 60 mg/day, later 100 mg/day) resulted in clinically stable disease for a period of 7 weeks, at which point the patient again progressed. Patient II had ER+ PR+ HER2- breast cancer in 2014 and developed metastatic disease in 2017. She was subsequently treated with fulvestrant/palbociclib before an NGS panel revealed a GOPC-ROS1 fusion. She had a brisk response to crizotinib, documented by both imaging and reduction in circulating CA27-29. After experiencing crizotinib-related pneumonitis, she switched to ceritinib (an alternative ROS1 inhibitor) and continues to have an excellent response following six months of anti-ROS1 treatment. Together, these cases underline the value of NGS panel sequencing in patients with metastatic breast cancer. Although alterations in crizotinib-sensitive pathways are quite rare in breast cancer, very substantial clinical responses may be observed if these patients can be identified.

Citation Format: Benjamin M. Parsons, David R. Meier, Sreeja Sreekumar, Craig S. Richmond, Kyle J. Ernzen, Kristopher A. Lofgren, Jake A. Deviley, Grzegorz T. Gurda, Paraic A. Kenny. Exceptional responses to crizotinib in breast cancer patients with somatic MET and ROS1 alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1317.

Sequential treatment failures in response to BRAF/MEK and immune checkpoint inhibitors mediated by MAP2K2 and B2M mutations in melanoma

Although the treatment of metastatic melanoma has been significantly improved by both anti-BRAF/MEK and checkpoint immunotherapies, resistance to these treatment modalities remains a substantial clinical problem. Multiple clinical studies are addressing the optimal sequencing of these agents in larger patient cohorts, but successful long-term individualized treatment will likely require the elucidation of resistance mechanisms from post-progression samples. Here, we describe a patient with BRAF-V600E-positive metastatic melanoma who was sequentially treated with BRAF/MEK inhibitors (dabrafenib/trametinib) and checkpoint inhibitor immunotherapy (nivolumab, followed by pembrolizumab). After the emergence of resistance, whole exome sequencing was performed, implicating MAP2K2 and B2M mutations in loss of response to anti-BRAF/MEK and anti-PD1 therapies, respectively.

MTORC1/2 Inhibition as a Therapeutic Strategy for PIK3CA Mutant Cancers

PIK3CA mutations are common in clinical molecular profiling, yet an effective means to target these cancers has yet to be developed. MTORC1 inhibitors are often used off-label for patients with PIK3CA mutant cancers with only limited data to support this approach. Here we describe a cohort of patients treated with cancers possessing mutations activating the PI3K signaling cascade with minimal benefit to treatment with the MTORC1 inhibitor everolimus. Previously, we demonstrated that dual PI3K/mTOR inhibition could decrease proliferation, induce differentiation, and result in a treatment response in APC and PIK3CA mutant colorectal cancer. However, reactivation of AKT was identified, indicating that the majority of the benefit may be secondary to MTORC1/2 inhibition. TAK-228, an MTORC1/2 inhibitor, was compared with dual PI3K/mTOR inhibition using BEZ235 in murine colorectal cancer spheroids. A reduction in spheroid size was observed with TAK-228 and BEZ235 (-13% and -14%, respectively) compared with an increase of >200% in control (P < 0.001). These spheroids were resistant to MTORC1 inhibition. In transgenic mice possessing Pik3ca and Apc mutations, BEZ235 and TAK-228 resulted in a median reduction in colon tumor size of 19% and 20%, respectively, with control tumors having a median increase of 18% (P = 0.02 and 0.004, respectively). This response correlated with a decrease in the phosphorylation of 4EBP1 and RPS6. MTORC1/2 inhibition is sufficient to overcome resistance to everolimus and induce a treatment response in PIK3CA mutant colorectal cancers and deserves investigation in clinical trials and in future combination regimens.

Abstract 1822: Emergence of MET D1228N mutation as a resistance mechanism following an exceptional response to crizotinib in a MET-amplified triple-negative breast cancer patient

The MET proto-oncogene encodes a receptor tyrosine kinase which is activated by Hepatocyte Growth Factor binding. Recent reports have described single agent activity for crizotinib in MET-amplified or mutant lung adenocarcinoma, squamous cell carcinoma and papillary renal cell carcinoma. Here we describe a stage IV triple-negative breast cancer patient in her early forties, previously treated with doxorubicin/cyclophosphamide, carboplatin/paclitaxel and with capecitabine. PET/CT imaging after progression on capecitabine revealed extensive metastatic disease including a large left pleural effusion, bilateral hypermetabolic nodular pleural implants, innumerable bilateral lung nodules and widespread mildly hyper-metabolic skeletal metastases in the ribs, spine and pelvis. A next-generation sequencing assay detected a 30-fold amplification of MET. MET amplification, overexpression and hyperactivity was confirmed by FISH and by immunohistochemistry for total MET and phospho-MET, respectively. Single agent crizotinib (250 mg, twice daily) was well-tolerated. Immunostaining of a biopsy taken after 9 days of treatment showed elimination of active phosphorylated MET, demonstrating in-tumor crizotinib efficacy at the clinical dose. CT imaging at 10 weeks showed a resolution of her metastatic disease, meeting RECIST 1.1 criteria for a complete response. This response was sustained at 22 weeks. At 37 weeks, the patient progressed in the pleura. An ultrasound guided biopsy revealed a robust resurgence of MET phosphorylation while still taking crizotinib, suggesting an alteration rendering MET recalcitrant to crizotinib. Next generation sequencing revealed a MET D1228N mutation, previously implicated in crizotinib resistance in lung cancer. This mutation was not detected in the pre-crizotinib biopsy (locus sequenced at 6300x) suggesting de novo acquisition in response to crizotinib. Transition from this type I MET inhibitor to a type II inhibitor (cabozantinib, initially 60 mg/day, later 100 mg/day) resulted in clinically stable disease for a period of 7 weeks, at which point the patient again progressed. Although MET-amplification is rare in breast cancer (~0.6% of cases), these data indicate that substantial clinical benefit may be achieved using single agent MET inhibition however the optimal selection of second-line agents to use upon progression will be critical.

Citation Format: Benjamin M. Parsons, David R. Meier, Grzegorz T. Gurda, Kristopher A. Lofgren, Paraic A. Kenny. Emergence of MET D1228N mutation as a resistance mechanism following an exceptional response to crizotinib in a MET-amplified triple-negative breast cancer patient [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1822.

A Strategy for Changing Adherence to National Guidelines for Decreasing Laboratory Testing for Early Breast Cancer Patients

INTRODUCTION

Past studies indicate delays in adoption of consensus-based guideline updates. In June 2016, the National Comprehensive Cancer Network changed its guidelines from routine testing to omission of ordering complete blood cell count (CBC) and liver function tests (LFT) in patients with early breast cancer. In response, we developed an implementation strategy to discontinue our historical practice of routine ordering of these tests in asymptomatic patients.

METHODS

The ordering of CBC and LFT for clinical stage I-IIIA breast cancer patients was audited in 2016. In June 2016, we utilized the levers of the National Quality Strategy implementation methodology to enact a system-wide change to omit routine ordering. To measure the plan's effectiveness, guideline compliance for ordering was tracked continually.

RESULTS

Of 92 patients with early stage cancer in 2016, the overall rate of compliance with guidelines for ordering a CBC and LFT was 82% (88/107) and 87% (93/107), respectively. Segregated by the pre- and post-guideline change time period, the compliance rates for ordering a CBC and LFT were 78% and 87% (P = 0.076).

CONCLUSION

In contrast to historical reports of delays in adoption of new evidence-based guideline changes, we were able to quickly change provider practice during the transition from routine ordering to omission of ordering screening blood tests in newly diagnosed patients with early breast cancer.

Implementation and Clinical Utility of an Integrated Academic-Community Regional Molecular Tumor Board

Purpose

Precision oncology develops and implements evidence-based personalized therapies that are based on specific genetic targets within each tumor. However, a major challenge that remains is the provision of a standardized, up-to-date, and evidenced-based precision medicine initiative across a geographic region.

Materials and Methods

We developed a statewide molecular tumor board that integrates academic and community oncology practices. The Precision Medicine Molecular Tumor Board (PMMTB) has three components: a biweekly Web-based teleconference tumor board meeting provided as a free clinical service, an observational research registry, and a monthly journal club to establish and revise evidence-based guidelines for off-label therapies. The PMMTB allows for flexible and rapid implementation of treatment, uniformity in practice, and the ability to track outcomes.

Results

We describe the implementation of the PMMTB and its first year of activity. Seventy-seven patient cases were presented, 48 were enrolled in a registry, and 38 had recommendations and clinical follow-up. The 38 subjects had diverse solid tumors (lung, 45%; GI, 21%; breast, 13%; other, 21%). Of these subjects, targeted therapy was recommended for 32 (84%). Clinical trials were identified for 24 subjects (63%), and nontrial targeted medicines for 16 (42%). Nine subjects (28%) received recommended therapy with a response rate of 17% (one of six) and a clinical benefit rate (partial response + stable disease) of 38% (three of eight). Although clinical trials often were identified, patients rarely enrolled.

Conclusion

The PMMTB provides a model for a regional molecular tumor board with clinical utility. This work highlights the need for outcome registries and improved access to clinical trials to pragmatically implement precision oncology.

Fewer Reoperations After Lumpectomy for Breast Cancer with Neoadjuvant Rather than Adjuvant Chemotherapy: A Report from the National Cancer Database

BACKGROUND

Reoperations occur frequently after initial lumpectomy for breast cancer. The authors hypothesized that the receipt of neoadjuvant chemotherapy (NAC) is associated with fewer reoperations.

METHODS

The association between timing of chemotherapy and reoperation rates (ROR) after lumpectomy was investigated for patients with stages 1-3 breast cancer in the National Cancer Database (NCDB) from 2010 to 2013 by multivariable logistic regression modeling. Then propensity score-matching was performed.

RESULTS

The unadjusted ROR for 71,627 stages 1-3 patients was 11.4% for those who had NAC compared with 20.3% for those who had postoperative chemotherapy (p < 0.001) (odds ratio [OR] 0.53; 95% confidence interval [CI] 0.49-0.57; p < 0.001). The ORs for the reoperations performed for patients with stages 1, 2, and 3 cancers who received NAC were respectively 0.65 (95% CI 0.56-0.75), 0.50 (95% CI 0.45-0.56), and 0.27 (95% CI 0.19-0.38) The p values for all were lower than 0.001.

CONCLUSION

For a population of patients receiving chemotherapy, the receipt of chemotherapy before instead of after surgery was associated with fewer reoperations after initial lumpectomy for breast cancer.

Cloning and characterization of Gallus and Xenopus ferrochelatases: presence of the [2Fe-2S] cluster in nonmammalian ferrochelatase

Ferrochelatase (EC 4.99.1.1) catalyzes the insertion of ferrous iron into protoporphyrin IX to form protoheme IX. This membrane-bound enzyme has been cloned from a variety of bacteria, plants, mammals, and yeast. Interestingly, only in mammals has the enzyme been found to contain a [2Fe-2S] cluster. Since the presence of this feature only in mammals would have significant evolutionary implications and because there have been no nonmammalian animal ferrochelatases cloned, expressed, and characterized, we report here the cloning and characterization of ferrochelatase from chicken (Gallus gallus) and an amphibian (Xenopus laevis). The cDNAs for both of these ferrochelatases were cloned by complementation of an Escherichia coli DeltahemH strain. The expressed and purified enzymes were characterized biochemically and both were found to contain [2Fe-2S] clusters. These clusters have spectral characteristics essentially identical to those of human ferrochelatase, although their EPR spectra are recognizably distinct from the human one. The [2Fe-2S] clusters of both chicken and amphibian ferrochelatases are readily destroyed by NO. Sequence analysis of the 3' UTR of both chicken and amphibian cDNAs show that while both have poly(A) tails neither have a consensus polyadenylation signal. The 5' UTR of Xenopus as isolated contained 135 bp and possesses no identifiable stem-loop structure.