Long Term Follow up of the Resort Study (E4402): A Randomized Phase III Study Comparing Two Different Rituximab Dosing Strategies for Low Tumor Burden Follicular Lymphoma

BACKGROUND: E4402 was a randomized phase III study comparing two different rituximab dosing strategies for patients with previously untreated, low tumor burden follicular lymphoma (FL). The primary endpoint was time to treatment failure. The initial publication (Kahl, JCO 2014) demonstrated that a retreatment strategy utilized less drug and produced comparable time to treatment failure compared to a maintenance strategy. Here we provide long term follow up results, focusing on response duration, time to first cytotoxic therapy, overall survival, and risk of histologic transformation. METHODS: Eligible patients had untreated, low tumor burden (GELF criteria) FL. Patients received R 375 mg/m 2 weekly x 4 and responders were randomized to maintenance rituximab (MR) (single dose R q 3 months) or retreatment rituximab (RR) (R weekly x 4 doses at disease progression). Each strategy was continued until treatment failure. The primary endpoint, time to treatment failure, was defined as progression within 6 months of last R, no response to R retreatment, initiation of alternative therapy, or inability to complete protocol therapy. Secondary endpoints included time to first cytotoxic therapy, quality of life and safety. The ECOG Data Monitoring Committee recommended release of study results at a planned interim analysis in September 2011 and patients and providers were notified of results. Time to treatment failure data collection halted with release of the results but limited data collection on time to first cytotoxic therapy, response duration, and risk of histologic transformation continued. INITITIAL RESULTS: From 11/03 to 9/08, 384 patients with FL were enrolled. Complete or partial response was achieved in 289 patients (71%), who were then randomized to MR (n=146) or RR (n=143). Demographic features were similar in the two arms: median age 59 years; ECOG PS 0-1 in all patients, and FLIPI low-risk (14.9 vs. 16.4%), intermediate-risk (46.3 vs. 42.9%) and high-risk (38.8 vs. 40.7%) for MR vs. RR, respectively. At initial publication, with a median follow-up of 3.8 years, the time to treatment failure was 3.9 years for MR vs. 3.6 years for RR (p=NS). LONG TERM FOLLOW UP RESULTS: Immunoglobulin levels and risks for serious infections/late complications in MR patients will be updated at the annual meeting. For the endpoint of time to first cytotoxic therapy, the median follow up is 8.7 years. At 7 years, 83% of MR and 63% of RR remained free from first cytotoxic therapy (HR 2.37; 95% CI 1.50 - 3.76) [Figure 1]. For the endpoint of response duration, the median follow up is 12.1 years. At 10 years, 66% of the MR patients remained in their 1 st remission compared to 30% of the RR patients who remained in their 1 st remission [Figure 2]. The median response duration for RR patients receiving a single 4-week course of rituximab was 3.25 years. There was no difference in the overall survival at 10 years, 84% for MR vs. 83% for RR. There was a trend towards a lower risk of histologic transformation for patients receiving MR (n = 4) compared to RR (n = 11) (p = 0.11). CONCLUSIONS: With long term follow up, the RESORT data indicates that in previously untreated, low tumor burden, follicular lymphoma, MR was superior to RR for delaying time to first cytotoxic therapy and for response duration, with a trend towards reducing the risk of histologic transformation. MR did not improve the overall survival. The original publication concluded that the time to treatment failure is similar between the two dosing strategies. Due to study design, time to treatment failure could not be analyzed in this long term follow up analysis. Compared to the historical benchmark of 3 years median time to first cytotoxic therapy when watch and wait is utilized, single agent rituximab, administered by either dosing strategy, was highly effective at delaying the time to first cytotoxic therapy. Figure 1 Figure 1. Disclosures Kahl: AbbVie, Adaptive, ADCT, AstraZeneca, Bayer, BeiGene, Bristol-Myers Squibb, Celgene, Genentech, Incyte, Janssen, Karyopharm, Kite, MEI, Pharmacyclics, Roche, TG Therapeutics, and Teva: Consultancy; AbbVie, Acerta, ADCT, AstraZeneca, BeiGene, Genentech: Research Funding. Habermann: Incyte: Other: Scientific Advisory Board; Tess Therapeutics: Other: Data Monitoring Committee; Seagen: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Schuster: Abbvie: Consultancy, Research Funding; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; Adaptive Biotechnologies: Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; DTRM: Research Funding; Genetech: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Incyte: Research Funding; Juno Theraputics: Consultancy, Research Funding; Loxo Oncology: Consultancy; Merck: Research Funding; Nordic Nanovector: Consultancy; Novartis: Consultancy, Honoraria, Patents & Royalties, Research Funding; Pharmaclcyclics: Research Funding; Tessa Theraputics: Consultancy; TG Theraputics: Research Funding. Fenske: TG Therapeutics: Consultancy, Speakers Bureau; Servier Pharmaceuticals: Consultancy; Seattle Genetics: Speakers Bureau; Sanofi: Speakers Bureau; Pharmacyclics: Consultancy; MorphoSys: Consultancy; Kite (Gilead): Speakers Bureau; KaryoPharm: Consultancy; CSL Therapeutics: Consultancy; Bristol-Myers Squibb: Speakers Bureau; Biogen: Consultancy; Beigene: Consultancy; AstraZeneca: Speakers Bureau; ADC Therapeutics: Consultancy; Adaptive Biotechnologies: Consultancy; AbbVie: Consultancy.

Clinical Outcome of t-AML with Respect to Genetic Abnormalities and Treatment Intensity - Single Center Analysis over the Past Two Decades

Background: Therapy-related acute myeloid leukemia (t-AML) represents emerging challenge of the modern oncology as a life-threatening complication of cytotoxic therapy. Disease characterises poor prognosis and presence of adverse cytogenetic and genetic abnormalities. The goal of the study: Clinical outcome of t-AML patients with respect to genetic changes and treatment intensity. Patients and methods: Retrospective analysis of all consecutive AML patients treated in years 2000-2021 in one hematological center was performed. Diagnosis of t-AML was established according to WHO 2016 criteria. Overall survival (OS) and progression free survival (PFS) was defined to evaluate treatment outcomes only within t-AML patients undergoing intensive treatment (standard induction/consolidation; allogeneic cell transplantation (alloHCT) if eligible). Results: Among 743 AML patients 60 (8.1%) were diagnosed as t-AML (38 woman) with median age 57 years. Solid tumors (ST) preceded t-AML in 63.3%, hematological neoplasms (HN) in 36.7%. Majority of t-AML was preceded by breast cancer (30.0%), Hodgkin Lymphoma (11.7%), non-Hodgkin Lymphoma (10.0%) and ovarian cancer (10.0%). Median latency time for ST and HN subgroups was 5 vs 7 years respectively (P = .036). Previous cytotoxic therapy consisted of chemotherapy, radiotherapy or combination in 56.6%, 18.3% and 25.0% (autologous cell transplantation was performed in 54.5% of HN). Cytogenetic and molecular biology analysis was performed in 44 and 27 of t-AML respectively. Cytogenetic abnormalities, complex karyotype and normal karyotype occurred in 78.9%, 28.9% and 15.8% patients. KMT2A, RUNX1-RUNX1T1 and PML-RARA rearrangement was found in 21.1%, 18.4% and 7.9% of t-AML. FLT3-ITD, FLT-TKD, NPM1 and C-KIT DNA sequence variant occurred as follows: 14.8%, 7.4%, 3.7% and 3.7% correspondingly. Three pathogenic TP53 DNA sequence variants were detected in t-AML patients: c.711G>A, c.704A>G and c.989T>C (analysis performed on 20 t-AML patients). According ELN2017 genetic risk stratification patients were classified as adverse, intermediate and favorable in 51.4%, 35.1% and 13.5% respectively. Intensive treatment was implemented in 48 patients including alloHCT in 23 of them. Median OS and PFS was 15 and 8 months respectively for whole treated group. Median OS in t-AML undergoing intensive chemotherapy only vs alloHCT was 7 vs 47 months (P = .0025) with 12-year OS after alloHCT- 21.1% (Fig.1A). Among therapy-related acute promyelocytic leukemia (t-APL) patients median OS was not reached, without alloHCT. Median OS was higher for t-AML patients younger than 65 years than older ones: 20 vs 13 months respectively (P = .048) (Fig.1B). Among t-AML median OS in subgroup with adverse ELN 2017 vs intermediate and favorable ELN 2017 was 15 vs 40 months (P = .037) with 5-years OS 8.2% vs 41.0% (Fig.1C). In multivariate Cox proportional hazard regression model alloHCT was the only factor significantly influencing OS (HR = 0.16, 95% CI = 0.05-0.56, P = .004). All patients with TP53 mutations were intensively treated, one patient underwent alloHCT. 66.6% of patients had complex karyotype and any co-occuring DNA sequence variant was detected. Importantly, c.704A>G and c.989T>C TP53 DNA sequence variants were not previously described in AML according Catalogue of Somatic Mutations In Cancer database. Median OS in t-AML with TP53 mutation vs without was 4 vs 7 months (P = .398) (Fig.1D). Conslusions: Our study brings detailed analysis of clinical outcome of t-AML. Patients with t-AML undergoing intensive treatment, younger than 65 years and with t-APL have significantly higher OS rates. On the contrary t-AML patients classified as adverse genetic ELN2017 subgroup have poorer OS rates. Treatment strategy in t-AML should rely on performing alloHCT possibly soon. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

CSIG-26. NF2/MERLIN DRIVES MENINGIOMA APOPTOSIS AND SUCEPTIBILITY TO CYTOTOXIC THERAPY

BACKGROUND Alterations in NF2 underlie meningioma tumorigenesis, but tumor suppressor functions of the NF2 gene product, Merlin, are incompletely understood in meningiomas. Here we integrate proteomic proximity-labelling mass spectrometry with CRISPR interference (CRISPRi), RNA sequencing, and biochemical approaches to discover Merlin drives meningioma apoptosis and susceptibility to cytotoxic therapy. METHODS RNA sequencing was performed on triplicate M10G meningioma cells stably expressing CRISPRi machinery and either non-targeting control sgRNAs, sgRNAs suppressing NF2, or sgRNAs suppressing NF2 with Merlin rescue. QPCR in IOMM-Lee and MSC1 meningioma cells expressing non-targeting control shRNAs or shRNAs suppressing NF2 was used for orthogonal validation in vitro. RNA sequencing of euploid meningiomas (n=52) or meningiomas with loss of NF2 as the only copy number variant (n=28) was used for orthogonal validation in vivo. Merlin interactors in meningioma cells were identified using APEX proteomic proximity-labelling mass spectrometry. Mechanistic and functional studies were performed using biochemical, molecular, and cell biology approaches in meningioma cells and CH-157MN meningioma xenografts treated with cytotoxic chemotherapy or ionizing radiation. RESULTS Merlin suppression in meningioma cells and xenografts inhibited pro-apoptotic interferon regulatory factor (IRF) target genes and attenuated meningioma apoptosis. Merlin suppression did not alter IRF stability or subcellular localization in meningioma cells, and proteomic proximity-labelling mass spectrometry revealed a novel interaction between wildtype Merlin and ARHGAP35, a DNA binding factor that inhibits glucocorticoid receptor expression (NR3C1). NR3C1 inhibits IRF activity to prevent apoptosis, and Merlin suppression in meningioma cells induced NR3C1expression, which was inhibited by Merlin rescue. Further, NR3C1 suppression rescued meningioma cell apoptosis in the absence of Merlin, and NR3C1 expression was increased in human meningiomas with loss of NF2 compared to euploid meningiomas. CONCLUSIONS These data shed light on a novel pro-apoptotic tumor suppressor function of Merlin regulating glucocorticoid signalling and susceptibility to cytotoxic therapy in meningiomas.

Acute Tumor Lysis Syndrome: A Metabolic Emergency in Cancer Patients

Tumor lysis syndrome (TLS) can be a life-threatening complication that occurs following the onset of chemotherapy treatment, most commonly in association with high-grade lymphoproliferative pathologies such as acute lymphoblastic leukemia and Burkitt lymphoma. The massive cell lysis caused by cytotoxic therapy leads to the rapid release in the blood of intracelullary products and the onset of severe metabolic and electrolytic complications (hyperkalemia, hyperphosphatemia, hypocalcemia and hyperuricemia) upto the acute renal failure. This article describes the incidence and pathophysiological basis of TLS, focusing on the new therapeutic strategies implemented over the last few years, especially with regard to the treatment of hyperuricemia. In particular, it highlights the characteristics of a recent drug, Rasburicase, as a safe and effective alternative, compared to traditional allopurinol therapy, for prophylaxis and treatment of children with hyperuricemia induced by chemotherapy.

LncRNA Miat and Metadhedrin maintain a treatment resistant stem-like niche of medulloblastoma cells

Medulloblastoma is a pediatric brain tumor arising from the cerebellum and brainstem that is curable with surgery and aggressive cytotoxic therapy including craniospinal irradiation and chemotherapy. Preclinical models indicate that a small pool of de-differentiated, stem cell-like medulloblastoma cells are resistant to cytotoxic treatment and contribute to medulloblastoma relapse after aggressive therapy. Here, we identify Miat as a Shh and Myc regulated long noncoding RNA (lncRNA) that is required for maintenance of a treatment-resistant medulloblastoma stem-like phenotype. Loss of Miat delays medulloblastoma formation in genetically defined mouse models of Shh medulloblastoma and enforces differentiation of tumorigenic stem-like medulloblastoma cells into a non-tumorigenic cell state. Miat facilitates treatment resistance in part by downregulating p53 signaling and impairing radiation induced cell death in stem-like MB cells, which can be reversed by therapeutic inhibition of Miat with antisense oligonucleotides. The RNA binding protein Metadhedrin (Mtdh), which is associated with resistance to cytotoxic therapy in numerous types of cancer, co-localizes with Miat in stem-like medulloblastoma cells. Further, loss of Mtdh activates p53 signaling and reduces tumorigenicity in stem-like medulloblastoma cells. Taken together, these data reveal a critical role for the lncRNA Miat in sustaining a treatment resistant pool of tumorigenic stem-like medulloblastoma cells.

Pharmacogenetic markers of chemotherapy toxicity in gastrointestinal tumors: a preliminary analysis

Aim. To assess the association between the carriage of minor allelic variants of 8 genes that encode key enzymes involved in the metabolism of anticancer drugs (DPYD, GSTP1, MTHFR, UGT1A1) and cell repair (XPC, ERCC1, TYMP, NQO1) and the severity of adverse drug events in patients with common gastrointestinal tumors. Tasks. To study the frequency of minor allelic variants of the DPYD, GSTP1, MTHFR, UGT1A1, XPC, ERCC1, TYMP, NQO1 genes; to assess the frequency and severity of adverse drug events of chemotherapy treatment in the study population. Materials and methods. For the period from October 2020 to April 2021, 56 patients (women 29, men 27) with verified malignant tumors of the gastrointestinal tract were included in a prospective clinical study as a part of the RSF grant No. 20-75-10158. The mean age was 62.311.4 years. Colon cancer was detected in 24 patients, tumors of the esophagus and stomach in 19 patients, tumors of pancreas and biliary tract in 13 patients. First-line palliative chemotherapy was given to 27 patients, adjuvant 19 patients, neoadjuvant 10 patients. All patients had not previously received cytotoxic or radiation treatment. Point nucleotide variants of genes DPYD, XPC, GSTP1, MTHFR, ERCC1, UGT1A1, TYMPS, NQO1 were determined by hybridization analysis on biological microchips. Differences in the tolerance of cytotoxic therapy (5-fluorouracil, platinum preparations, irinotecan) depending on the genotype were assessed using Fishers exact test. Results. The average number of chemotherapy courses received was 4.22.6 (112). There was a statistically significant difference in the tolerability of chemotherapy in patients with minor allelic variants of the GSTP1 rs1695 (p=0.03), ERCC1 rs11615 (p=0.01), and UGT1A1 rs8175347 (p=0.003) genes. Conclusion. The use of hybridization analysis on biological microchips to assess allelic variants responsible for the tolerability of cytotoxic therapy is reasonable and requires further prospective assessment.

COVID-19 related outcomes for hospitalized patients (pts) with solid malignancies (SM).

e18626 Background: Pts with malignancies are at risk for developing severe complications of COVID-19 with high mortality rate. We retrospectively analyzed COVID-19 related outcomes for hospitalized pts with SMs. Methods: We collected data on hospitalized pts with SMs and COVID-19 from 3/1/20 to Jan 1/1/21. Diagnosis COVID-19 was confirmed by RT-PCR of nasopharyngeal swabs. We assessed the association between the 30-day mortality and potential prognostic variables such as tumor types, cancer status, timing of treatment, types of anticancer therapy using logistic regression analyses. Results: A total of 246 hospitalized pts with SMs had COVID-19. Median age was 70 years, 87 (35%) were ≥75 years, 151 (61%) were female. The most common SMs were breast (56 [23%]), non-small cell lung (44 [18%]) and colon (31 [13%]). 154 (63%) pts were on active anticancer therapies. Of those 88 (35.5%) received treatment within 2 weeks, 16 (16.5%) within 4-12 weeks, 99 (39.9%) >3 months prior to COVID-19 diagnosis. 101 (65%) pts received cytotoxic chemotherapies, 26 (16.8%) received immune check point inhibitors (ICIs), 17 (11%) received targeted agents such as anti-EGFR therapy and 11 (7.1%) received monoclonal antibodies. Overall 30-day mortality was 42%, however, all pts with melanoma (7/7) died. The 30-day mortalities for pts who received anticancer treatments within 4 weeks, 4-12 weeks and >12 weeks of COVID-19 diagnosis were 47%, 50%, and 37%. For pts who never received treatment, 30-day mortality was 31%. For pts were in remission, stable disease and progressive disease, the 30-day mortalities were 32%, 35% and 62%. The 30-day mortalities for pts who received cytotoxic therapy, monoclonal antibodies, targeted therapies and ICIs, were 38%, 46%, 41% and 69%. Logistic regression analysis showed that pts who were >80 years of age (OR 3.6, 95% CI 1.6-8.1), had progressive disease (OR 3.4, 95% CI 1.8-6.5) or treated with ICIs (OR 3.6, 95% CI 1.5-8.7) were associated with higher 30-day mortality. Conclusions: COVID-19 associated 30-day mortality is high for hospitalized pts with SMs. Early surveillance of clinical deterioration could be helpful for hospitalized SMs pts with risk factors identified here. Further studies are needed to discern the observed association between ICIs use and worse COVID-19 outcome.[Table: see text]

A randomized phase II study comparing cisplatin and gemcitabine with or without berzosertib in patients with advanced urothelial carcinoma.

4507 Background: Cisplatin with gemcitabine (CG) remains the standard upfront chemotherapy regimen for metastatic urothelial cancer (mUC). Preclinical synergy was noted between cisplatin and berzosertib, a selective ATR inhibitor. The current study sought to determine if the combination of berzosertib and CG could improve clinical outcomes in mUC. Methods: An open-label, randomized study was conducted across 23 centers in the United States through the Experimental Therapeutics Clinical Trials Network of the National Cancer Institute. Key eligibility criteria included confirmed mUC, no prior cytotoxic therapy for metastatic disease, ≥ 12 months since perioperative therapy and eligibility for cisplatin based on standard criteria. Patients (pts) were randomized to receive either CG alone (control arm) or CG plus berzosertib (experimental arm). In the control arm, 70 mg/m2 of cisplatin was given on day 1 and gemcitabine at 1000 mg/m2 on days 1 and 8 of a 21-day cycle. In the experimental arm, 60 mg/m2 of cisplatin was given on day 1, gemcitabine at 875 mg/m2 on days 1 and 8 and berzosertib at 90 mg/m2 on days 2 and 9 of a 21-day cycle. The primary endpoint of the study was progression-free survival (PFS), with secondary endpoints including response rate (RR), overall survival (OS) and toxicity. Results: A total of 87 pts (median age 67; M:F 68:19) were randomized; 41 pts received CG alone while 46 received CG with berzosertib. Visceral metastases were present in 49% of pts and 52%, 45% and 3% of pts were Bajorin risk 0, 1 and 2, respectively. Median PFS was 8.0 months for both arms (Bajorin risk adjusted hazard ratio [HR] 1.22, 95% confidence interval [CI] 0.72-2.08). RR was 54%(4 CR, 21 PR) in the CG with berzosertib arm and 63% (4 CR, 22 PR) in CG alone arm (P = 0.66). Median OS was shorter with CG with berzosertib as compared to CG alone (14.4 versus 19.8 months; Bajorin risk adjusted HR 1.42, 95%CI 0.76-2.68). Notably higher rates of grade 3/4 thrombocytopenia (59% vs 39%) and neutropenia (37% vs 27%) were observed with CG plus berzosertib compared to CG alone. Higher rates of toxicity-related discontinuation were seen in the experimental arm (24% vs 15%), and the median cumulative cisplatin dose in the experimental arm was 250 mg/m2, as compared to 370 mg/m2 in the control arm (P < 0.001). Conclusions: No improvement in PFS was observed with the addition of berzosertib to CG, and a trend towards inferior survival was observed. These results suggest caution in reducing the starting dose of cytotoxic therapy to accommodate addition of a myelosuppressive agent, as in the experimental arm of this study. Clinical trial information: NCT02567409.

Noninvasive identification of emergent mutations following cytotoxic therapy for lung cancer.

8533 Background: Lung cancer is the leading cause of cancer death world-wide, and chemotherapy and radiation remain backbones of therapy for patients with locoregionally advanced and metastatic disease. However, the genetic mechanisms that mediate resistance to chemotherapy and radiation are largely unclear due to a lack of available tissue at the time of relapse. We hypothesized that circulating tumor DNA (ctDNA) analysis could identify emergent mutations after chemotherapy and radiation that may lead to treatment resistance. Methods: To identify emergent mutations at the time of progression following an initial response to chemotherapy and/or radiation therapy for lung cancer, we utilized CAncer Personalized Profiling by deep Sequencing (CAPP-Seq) to analyze plasma samples and matched leukocytes collected pre-treatment and at the time of relapse. We analyzed a targeted panel enriched for lung cancer drivers and recurrently mutated genes for 27 patients treated with chemoradiation therapy for locoregionally advanced lung cancer. In addition, we performed ultra-deep whole exome sequencing ( > 2000X deduped depth) of pre-treatment and relapse cell-free DNA for 5 patients treated with combination chemotherapy for metastatic lung cancer. Functional enrichment analysis was performed on emergent mutation gene lists to identify significantly enriched pathways. Results: We identified emergent variants in 6 out of 27 patients using targeted sequencing after chemoradiation therapy. Emergent mutations after chemoradiation were enriched for plasma membrane adhesion molecules such as PCDH17, PCDH10, and FAT3 (adjusted P = 0.03). Using ultra-deep whole exome sequencing, we observed emergent mutations in 3 out of 5 patients treated with combination chemotherapy. After combination chemotherapy, there was a trend towards enrichment in mutations in ATP-binding cassette transporters, including ABCA13 and ABCB4 (adjusted P = 0.057). Notably, there were no recurrent emergent mutations within our cohort. Conclusions: Our results suggest that ultra-deep whole exome sequencing can non-invasively identify emergent mutations at the time of progression. Resistance to cytotoxic therapy is likely multi-factorial and analysis in expanded cohorts will be helpful to identify recurrently mutated pathways that may contribute to disease progression after an initial response to therapy.