Mosunetuzumab with polatuzumab vedotin in relapsed or refractory aggressive large B cell lymphoma: a phase 1b/2 trial

Relapsed/refractory aggressive large B cell lymphoma (LBCL) remains an area of unmet need. Here we report the primary analysis of a phase 1b/2 trial of outpatient mosunetuzumab (a CD20xCD3 T-cell-engaging bispecific antibody) plus polatuzumab vedotin (an anti-CD79B antibody-drug conjugate) in relapsed/refractory LBCL. The phase 2 component is a single arm of an ongoing multi-arm trial. The primary endpoint during dose expansion was independent review committee (IRC)-assessed best overall response rate. Secondary endpoints included investigator-assessed overall response rate, complete response, duration of response, progression-free survival and overall survival. At data cutoff, 120 patients were enrolled (22 dose escalation, 98 dose expansion). The primary endpoint was met during dose expansion, with IRC-assessed best overall response rate and complete response rates of 59.2% (58/98; 95% confidence interval (CI): 48.8-69.0) and 45.9% (45/98; 95% CI: 35.8-56.3), respectively (median follow-up, 23.9 months). Median duration of complete was not reached (95% CI: 20.5-not estimable (NE)). Median progression-free survival was 11.4 months (95% CI: 6.2-18.7). Median overall survival was 23.3 months (95% CI: 14.8-NE). Across dose escalation and expansion, the most common grade 3 or higher adverse events were neutropenia (25.0%, 30/120) and fatigue (6.7%, 8/120). Any-grade cytokine release syndrome occurred in 16.7% of patients. These data demonstrate that mosunetuzumab plus polatuzumab vedotin has a favorable safety profile with highly durable responses suitable as second-line therapy in transplant-ineligible relapsed/refractory LBCL. ClinicalTrials.gov identifier: NCT03671018 .

Overall survival of patients with cHL who progress after autologous stem cell transplant: results in the novel agent era

In the pre-novel agent era, the median postprogression overall survival (PPS) of patients with classic Hodgkin lymphoma (cHL) who progress after autologous stem cell transplant (ASCT) was 2 to 3 years. Recently, checkpoint inhibitors (CPI) and brentuximab vedotin (BV) have improved the depth and durability of response in this population. Here, we report the estimate of PPS in patients with relapsed cHL after ASCT in the era of CPI and BV. In this multicenter retrospective study of 15 participating institutions, adult patients with relapsed cHL after ASCT were included. Study objective was postprogression overall survival (PPS), defined as the time from posttransplant progression to death or last follow-up. Of 1158 patients who underwent ASCT, 367 had progressive disease. Median age was 34 years (range, 27-46) and 192 were male. Median PPS was 114.57 months (95% confidence interval [CI], 91-not achieved) or 9.5 years. In multivariate analysis, increasing age, progression within 6 months, and pre-ASCT positive positron emission tomography scan were associated with inferior PPS. When adjusted for these features, patients who received CPI, but not BV, as first treatment for post-ASCT progression had significantly higher PPS than the no CPI/no BV group (hazard ratio, 3.5; 95% CI, 1.6-7.8; P = .001). Receipt of allogeneic SCT (Allo-SCT) did not improve PPS. In the era of novel agents, progressive cHL after ASCT had long survival that compares favorably with previous reports. Patients who receive CPI as first treatment for progression had higher PPS. Receipt to Allo-SCT was not associated with PPS in this population.

Lisocabtagene maraleucel in chronic lymphocytic leukaemia and small lymphocytic lymphoma (TRANSCEND CLL 004): a multicentre, open-label, single-arm, phase 1-2 study

BACKGROUND

Patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma for whom treatment has failed with both Bruton tyrosine kinase (BTK) inhibitor and venetoclax have few treatment options and poor outcomes. We aimed to evaluate the efficacy and safety of lisocabtagene maraleucel (liso-cel) at the recommended phase 2 dose in patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma.

METHODS

We report the primary analysis of TRANSCEND CLL 004, an open-label, single-arm, phase 1-2 study conducted in the USA. Patients aged 18 years or older with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma and at least two previous lines of therapy, including a BTK inhibitor, received an intravenous infusion of liso-cel at one of two target dose levels: 50 × 106 (dose level 1) or 100 × 106 (dose level 2, DL2) chimeric antigen receptor-positive T cells. The primary endpoint was complete response or remission (including with incomplete marrow recovery), assessed by independent review according to the 2018 International Workshop on Chronic Lymphocytic Leukemia criteria, in efficacy-evaluable patients with previous BTK inhibitor progression and venetoclax failure (the primary efficacy analysis set) at DL2 (null hypothesis of ≤5%). This trial is registered with ClinicalTrials.gov, NCT03331198.

FINDINGS

Between Jan 2, 2018, and June 16, 2022, 137 enrolled patients underwent leukapheresis at 27 sites in the USA. 117 patients received liso-cel (median age 65 years [IQR 59-70]; 37 [32%] female and 80 [68%] male; 99 [85%] White, five [4%] Black or African American, two [2%] other races, and 11 [9%] unknown race; median of five previous lines of therapy [IQR 3-7]); all 117 participants had received and had treatment failure on a previous BTK inhibitor. A subset of patients had also experienced venetoclax failure (n=70). In the primary efficacy analysis set at DL2 (n=49), the rate of complete response or remission (including with incomplete marrow recovery) was statistically significant at 18% (n=9; 95% CI 9-32; p=0·0006). In patients treated with liso-cel, grade 3 cytokine release syndrome was reported in ten (9%) of 117 (with no grade 4 or 5 events) and grade 3 neurological events were reported in 21 (18%; one [1%] grade 4, no grade 5 events). Among 51 deaths on the study, 43 occurred after liso-cel infusion, of which five were due to treatment-emergent adverse events (within 90 days of liso-cel infusion). One death was related to liso-cel (macrophage activation syndrome-haemophagocytic lymphohistiocytosis).

INTERPRETATION

A single infusion of liso-cel was shown to induce complete response or remission (including with incomplete marrow recovery) in patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma, including patients who had experienced disease progression on a previous BTK inhibitor and venetoclax failure. The safety profile was manageable.

FUNDING

Juno Therapeutics, a Bristol-Myers Squibb Company.

Survival with Axicabtagene Ciloleucel in Large B-Cell Lymphoma

BACKGROUND

In an analysis of the primary outcome of this phase 3 trial, patients with early relapsed or refractory large B-cell lymphoma who received axicabtagene ciloleucel (axi-cel), an autologous anti-CD19 chimeric antigen receptor T-cell therapy, as second-line treatment had significantly longer event-free survival than those who received standard care. Data were needed on longer-term outcomes.

METHODS

In this trial, we randomly assigned patients with early relapsed or refractory large B-cell lymphoma in a 1:1 ratio to receive either axi-cel or standard care (two to three cycles of chemoimmunotherapy followed by high-dose chemotherapy with autologous stem-cell transplantation in patients who had a response). The primary outcome was event-free survival, and key secondary outcomes were response and overall survival. Here, we report the results of the prespecified overall survival analysis at 5 years after the first patient underwent randomization.

RESULTS

A total of 359 patients underwent randomization to receive axi-cel (180 patients) or standard care (179 patients). At a median follow-up of 47.2 months, death had been reported in 82 patients in the axi-cel group and in 95 patients in the standard-care group. The median overall survival was not reached in the axi-cel group and was 31.1 months in the standard-care group; the estimated 4-year overall survival was 54.6% and 46.0%, respectively (hazard ratio for death, 0.73; 95% confidence interval [CI], 0.54 to 0.98; P = 0.03 by stratified two-sided log-rank test). This increased survival with axi-cel was observed in the intention-to-treat population, which included 74% of patients with primary refractory disease and other high-risk features. The median investigator-assessed progression-free survival was 14.7 months in the axi-cel group and 3.7 months in the standard-care group, with estimated 4-year percentages of 41.8% and 24.4%, respectively (hazard ratio, 0.51; 95% CI, 0.38 to 0.67). No new treatment-related deaths had occurred since the primary analysis of event-free survival.

CONCLUSIONS

At a median follow-up of 47.2 months, axi-cel as second-line treatment for patients with early relapsed or refractory large B-cell lymphoma resulted in significantly longer overall survival than standard care. (Funded by Kite; ZUMA-7 ClinicalTrials.gov number, NCT03391466.).

Checkpoint inhibitor-based salvage regimens prior to autologous stem cell transplant improve event-free survival in relapsed/refractory classic Hodgkin lymphoma

Clinical trials of novel salvage therapies have encouraging outcomes for relapsed/refractory transplant-eligible classic Hodgkin lymphoma (R/R cHL) but comparison with conventional chemotherapy is lacking. Herein, we report the final analysis of a multicenter retrospective cohort of R/R cHL assessing outcomes by type of salvage therapy before autologous stem cell transplant (ASCT). R/R cHL patients who underwent ASCT at 14 institutions across the United States were included. Outcomes were compared among patients receiving conventional chemotherapy, brentuximab vedotin (BV) + chemotherapy, BV alone, and a checkpoint inhibitor (CPI)-based regimens before ASCT. Study endpoints included event-free survival (EFS), progression-free survival (PFS), and overall survival (OS). All endpoints are defined from relapse. Of 936 patients, 728 received conventional chemotherapy, 73 received BV + chemotherapy, 70 received BV alone, and 65 received CPI-based regimens prior to ASCT. When adjusted for time to relapse, pre-ASCT response and use of BV maintenance, patients receiving CPI-based regimens had superior 2-year EFS compared to conventional chemotherapy, BV + chemotherapy, and BV alone (79.7, 49.6, 62.3, and 36.9%, respectively, p < .0001). Among 649 patients transplanted after 1 line of salvage therapy, CPI-based regimens were associated with superior 2-year PFS compared to conventional chemotherapy (98% vs. 68.8%, hazard ratio: 0.1, 95% confidence interval: 0.03-0.5, p < .0001). OS did not differ by pre-ASCT salvage regimen. In this large multicenter retrospective study, CPI-based regimens improved EFS and PFS compared to other salvage regimens independent of pre-ASCT response. These data support earlier sequencing of CPI-based regimens in R/R cHL in the pre-ASCT setting.

CD-19 CART therapy and orthostatic hypotension: a single center retrospective cohort study

Background

Chimeric antigen receptor T-cell (CART) therapy is a form of cellular immunotherapy used to treat hematologic malignancies. Major adverse cardiovascular events have been seen in CART patients who have high grade CRS, higher baseline creatinine, and troponin elevation. However, the incidence and factors associated with orthostatic hypotension after CART therapy have not previously been reported in the literature.

Methods

We looked at patients who underwent CD-19 directed CART therapy at UPMC Shadyside hospital from April 1^st 2018 to December 1^st 2020. Patients were classified as having orthostatic hypotension if they had recorded orthostatic vital signs that were positive or provider notes indicated that vitals had been taken and were positive in the time period from discharge to 3 months post-CART. Data was analyzed with univariate and multivariate analysis using logistic regression.

Results

79% of patients had orthostatic hypotension after discharge from their CART hospitalization and 64% of those patients were symptomatic. Older age, lower BMI, lower ambulatory diastolic blood pressure and grade 2 CRS were associated with orthostatic hypotension in the univariate analysis. Older age and lower ambulatory systolic blood pressure were associated with orthostatic hypotension in the multivariate analysis. Symptomatic orthostatic hypotension was associated with a history of hypertension in both the univariate and multivariate analysis. Patients with symptoms also had a higher pre-CART ejection fraction but this association was not seen in the regression model.

Conclusion

There is a high incidence of orthostatic hypotension after CART therapy even after discharge. Therefore, orthostatic vitals signs and associated symptoms should be assessed in both the inpatient and outpatient setting. Older patients and patients with lower BMIs, lower ambulatory blood pressures, grade 2 CRS, or a history of hypertension may need closer monitoring.

Patient-reported outcomes in ZUMA-7, a phase 3 study of axicabtagene ciloleucel in second-line large B-cell lymphoma

Here, we report the first comparative analysis of patient-reported outcomes (PROs) with chimeric antigen receptor T-cell therapy vs standard-of-care (SOC) therapy in second-line relapsed/refractory large B-cell lymphoma (R/R LBCL) from the pivotal randomized phase 3 ZUMA-7 study of axicabtagene ciloleucel (axi-cel) vs SOC. PRO instruments were administered at baseline, day 50, day 100, day 150, month 9, and every 3 months from randomization until 24 months or an event-free survival event. The quality of life (QoL) analysis set comprised patients with a baseline and ≥1 follow-up PRO completion. Prespecified hypotheses for Quality of Life Questionnaire-Core 30 (QLQ-C30) physical functioning, global health status/QoL, and EQ-5D-5L visual analog scale (VAS) were tested using mixed-effects models with repeated measures. Clinically meaningful changes were defined as 10 points for QLQ-C30 and 7 for EQ-5D-5L VAS. Among 359 patients, 296 (165 axi-cel, 131 SOC) met inclusion criteria for QoL analysis. At day 100, statistically significant and clinically meaningful differences in mean change of scores from baseline were observed favoring axi-cel over SOC for QLQ-C30 global health status/QoL (estimated difference 18.1 [95% confidence interval (CI), 12.3-23.9]), physical functioning (13.1 [95% CI, 8.0-18.2]), and EQ-5D-5L VAS (13.7 [95% CI, 8.5-18.8]; P < .0001 for all). At day 150, scores significantly favored axi-cel vs SOC for global health status/QoL (9.8 [95% CI, 2.6-17.0]; P = .0124) and EQ-5D-5L VAS (11.3 [95% CI, 5.4-17.1]; P = .0004). Axi-cel showed clinically meaningful improvements in QoL over SOC. Superior clinical outcomes and favorable patient experience with axi-cel should help inform treatment choices in second-line R/R LBCL. This trial was registered at www.clinicaltrials.gov as #NCT03391466.

202. The Impact and Safety of Discontinuing Routine Surveillance Blood Culture Monitoring in Allogeneic Hematopoietic Cell Transplant Recipients

Background

Bloodstream infections (BSI) cause significant morbidity and mortality after hematopoietic cell transplant recipients (HCT). Surveillance blood cultures (SBC) are commonly used to decrease the risk of developing BSI but prior data suggest limited clinical utility. At our center, SBC monitoring was discontinued on 12/1/2019. This is a single center study evaluating the impact and safety of discontinuing routine SBC monitoring.

Methods

Retrospective review of allogeneic hematopoietic cell transplant recipients (HCTR) seen before (12/1/2017 – 11/30/2019) and after (12/1/2019 - 12/1/2020) discontinuation of SBC. We evaluated utility of SBC and the impact of discontinuation of SBC on admissions, mortality, and other variables.

Results

One hundred thirty-six and 133 HCTR were followed before and after discontinuation of SBC, respectively. Median (range) ages were 58 (22-73) and 56 (19-73); 60 (44%) and 59 (44%) were female, respectively. The most common cancer was acute myelogenous leukemia (71 (52%) and 61 (46%)); 87 (64%) and 77 (58%) had graft-versus-host disease respectively. Pre-intervention, 1946 SBCs were drawn; 81/1946 (4.2%) were positive. Post-intervention, 29 SBC were drawn; 1/29 (3.4%) were positive. Of the 82 positive SBCs, 63 (77%) were skin flora, and 9 (11%) were gram negative rods. No cultures grew Staphylococcus aureus or fungi. Fifty-one (63%) of the positive SBC resulted in an admission; median (range) length of stay (LOS) was 3 days (1-11). Following discontinuation of SBC, median monthly blood culture-related admissions decreased from 3 (0-6) to 1 (0-3) shown in Figure 1. In the pre-intervention period, there were 2 BSI-related deaths, and 0 following cessation of SBCs.

Figure 1. Monthly Hospital Admissions for Positive Outpatient Blood Cultures

Conclusion

SBCs were infrequently positive and often resulted in unnecessary antibiotic use, admission, and clinical interventions. After SBC monitoring was discontinued, there was a decrease in hospital admissions and health care utilization for positive blood cultures drawn in the outpatient setting. This intervention did not negatively impact clinical outcomes, including BSI-related mortality. Discontinuation of SBC appears to be safe and results in a reduction in healthcare utilization. Centers performing SBC should consider eliminating this practice.

Disclosures

Ghady Haidar, MD, Karuys (Grant/Research Support)

Invasive Mold Infections After Chimeric Antigen Receptor-Modified T-Cell Therapy: A Case Series, Review of the Literature, and Implications for Prophylaxis

Data on invasive mold infections (IMIs) after chimeric antigen receptor-modified T-cell (CAR-T-cell) therapy are limited. We describe 2 patients with post-CAR-T-cell IMI (Fusarium, Mucorales) and review the published literature. We propose strategies to prevent IMIs in patients, based on the IMI rate and presence of neutropenia or steroid use.

1105. The Burden of Infections Prior to Chimeric Antigen Receptor (CAR) Modified T-cell Therapy Predicts Post-CAR T-cell Infectious Complications

Background

CAR T -cell therapy (CTT) is a novel treatment for B-cell cancers. CTT patients (pt) are at risk of infection due to neutropenia, cytokine release syndrome (CRS), and CAR T-cell related encephalopathy syndrome (CRES), which are treated with steroids and tocilizumab (anti-IL-6). This is a single-center study evaluating the risk factors for infection after CTT.

Methods

A retrospective review was conducted of 60 consecutive CTT recipients between 7/17/17 and 9/5/19. Data was collected from 6 months (mo) pre- and at least 6 mo post-CTT. Data was censored for death, additional chemotherapy, or loss to follow up. Cox proportional hazard and Poisson regression were used.

Results

Median age was 66 (23-84) years; 48% (29) were female. The most common cancer was non-Hodgkin lymphoma (89%, 54). 25% (15) had a prior stem cell transplant (SCT). 73% (44) and 45% (27) of pts developed CRS and CRES, respectively. 43% (26) received steroids; 65% (39) received tocilizumab. In the 6 mo pre-CTT, 39 infections occurred in 45% (27) of pts. 103 infections occurred in 66% (40) after CTT; 33 (55%) had an infection within 6 mo. Infections were bacterial (52%; 54/103), viral (30%; 37/103), fungal (10%; 10/103), mycobacterial (1%; 1/103), protozoal (1%; 1/103). Cumulative incidence of infection in the first 6 mo are shown in Fig 1. All-cause and infection-related mortality were 32% (19) and 15% (9), respectively. Mortality among pts with fungal infections was 20% (2/10). Infection density was 1.28 and 0.58 infections per 100 pt-days between days 0-30 and 30-89, respectively. Factors associated with infection post CTT were number (no.) of infections in the 6 mo prior to infusion (HR 1.62, CI [1.1-2.38]; p=0.015), no. of lines of therapy in the 6 mo pre-CTT (HR 1.52, CI [1.01-2.27]; p=0.04), prior allogeneic SCT (HR 5.96, CI [1.34-26.47]; p=0.019), and no. of tocilizumab doses. Grade 1 CRS and grade 2 CRES were risk factors between days 0-30 and 0-180, respectively (HR 4.67, CI [1.02 -21.4], p = 0.047; HR 2.48, CI [1.17-5.23], p = 0.02).

Fig 1: Cumulative Incidence of Infection 6 Months Post CAR T-cell Therapy

Conclusion

Infections after CTT are common. Infection before CTT was associated with risk of infection after CTT. Pt selection may ameliorate this risk. Mortality due to fungal infections was high. Randomized-controlled trials of antifungal prophylaxis in high-risk pts are needed.

Disclosures

All Authors: No reported disclosures

A phase-1 study of dasatinib plus all-trans retinoic acid in acute myeloid leukemia

Src family kinases (SFKs) are hyperactivated in acute myeloid leukemia (AML). SFKs impede the retinoic acid receptor, and SFK inhibitors enhance all-trans retinoic acid (ATRA)-mediated cellular differentiation in AML cell lines and primary blasts. To translate these findings into the clinic, we undertook a phase-I dose-escalation study of the combination of the SFK inhibitor dasatinib and ATRA in patients with high-risk myeloid neoplasms. Nine subjects were enrolled: six received 70 mg dasatinib plus 45 mg/m² ATRA daily, and three received 100 mg dasatinib plus 45 mg/m² ATRA daily for 28 days. Headache and QTc prolongations were the only two grade 3 adverse events observed. No significant clinical responses were observed. We conclude that the combination of 70 mg dasatinib and 45 mg/m² ATRA daily is safe with acceptable toxicity. Our results provide the safety profile for further investigations into the clinical efficacy of this combination therapy in myeloid malignancies.

Histopathology of Graft-vs-Host Disease of Gastrointestinal Tract and Liver: An Update

OBJECTIVES

Graft-vs-host disease (GVHD) is a donor T-cell-mediated disorder affecting the recipient's skin, gastrointestinal tract, lungs, and liver. It complicates up to 70% of hematopoietic cell transplantation and is associated with high morbidity and mortality rates.

METHODS

An extensive review of the literature has been performed to include the most current consensus on the histopathologic diagnosis of gastrointestinal and liver GVHD.

RESULTS

In this review, we present an overview of GVHD, with emphasis on the histopathologic evaluation of gastrointestinal and liver specimens, including the most important differential diagnoses and possible pitfalls.

CONCLUSIONS

Histopathologic examination remains the mainstay of diagnosis of gastrointestinal and liver GVHD and is interpreted in conjunction with clinical and laboratory data.

Peri-transplant clostridium difficile infections in patients undergoing allogeneic hematopoietic progenitor cell transplant

Clostridium difficile infections (CDI) remain the leading cause of infectious diarrhea among hospitalized patients in this country. Patients with hematologic malignancies, especially those who undergo hematopoietic progenitor cell transplants are particularly at risk for developing CDI. One hundred and forty seven consecutive allogeneic hematopoietic progenitor cell transplants were analyzed for peri-transplant Clostridium difficile infections (PT-CDI). Sixteen patients (11%) developed PT-CDI (Median time = 7 days after transplant). The probability for developing PT-CDI during the peri-transplant period was 12.3%. History of CDI was strongly associated with the development of PT-CDI (P = 0.008) (OR = 5.48) (P = 0.017). These patients also developed PT-CDI much earlier than in those without a history (median 1 day vs. 8 days, P = 0.03). The probability for developing PT-CDI for those with a history was 39%. There was a trend toward significance (P = 0.065) between matched related donor grafts and the development of PT-CDI (OR = 0.245) (P = 0.08). Age, sex, diagnosis, transplant preparative regimens, Graft-versus-host disease (GVHD) prophylaxis, grade 3/4 acute GVHD, or use of antimicrobials within 8 weeks of transplant were not associated with PT-CDI. Non-CDI-related deaths occurred in one patient in the PT-CDI group and nine in the group without PT-CDI. In the remaining 139 patients, the length of hospital stay for those with PT-CDI was significantly longer than those without (mean 27 days vs. 22 days; P = 0.02).

Inferior outcome after allogeneic transplant in first remission in high-risk AML patients who required more than two cycles of induction therapy

While some patients with high-risk acute myeloid leukemia (AML) require one or two cycles of induction chemotherapy to achieve a complete remission (CR), others require more than two cycles. We examined the outcomes of patients with high-risk AML who received allogeneic HPC transplant in CR1. Forty five consecutive high-risk AML patients in CR1 were included. All 45 patients had adverse cytogenetics, FLT 3 mutations, or secondary AML. Group A patients (n = 33) received one or two cycles, and Group B (n = 12) three or more cycles of induction chemotherapy. The patients were comparable in age, sex, white cell count at presentation, and time from diagnosis and from last chemotherapy to transplant. The 100-day mortality rate was higher in Group B patients (50% vs. 9%, P = 0.006). They had a higher non-relapse mortality (33% vs. 6%, P = 0.035) and a longer length of hospital stay from the day of stem cell infusion (median 21 vs. 20, P = 0.02; third quartile 22 vs. 28, P = 0.02). There was also a trend toward inferior event-free survival and overall survival. High-risk AML patients undergoing allogeneic transplant in CR1 after three or more cycles of induction chemotherapy have an inferior outcome and higher mortality when compared to those who only needed one or two cycles of induction chemotherapy. Novel strategies are needed to reduce the transplant-related mortality in high-risk AML patients needing more than two cycles of induction chemotherapy prior to allogeneic transplant in CR1.

Abstract 2439: Obatoclax (GX15-070) potently induces apoptosis in head and neck squamous cell carcinoma (HNSCC) cell lines and enhances the activity of EGFR inhibitors

HNSCC represents 90% of head and neck tumors. More than half of HNSCC patients are initially treated with curative intent, but will relapse over the course of their disease and have poor prognosis with a median survival of 6-9 months. Novel therapeutic approaches are in desperate need for this patient population. The antiapoptotic BCL-2 family proteins like BCL-2, BCL-XL, and MCL-1 are involved in oncogenesis and chemoresistance and are overexpressed in HNSCC. Obatoclax is a small-molecule antagonist of the BH3-binding groove of the prosurvival (or anti-apoptotic) members of the BCL-2 family of proteins. It is the only compound among the current BCL-2 inhibitors in clinical trials that is capable of inhibiting MCL-1, in addition to BCL-2 and BCL-XL. We determined the activity of obatoclax in 4 HNSCC cell lines (UMSCC-1, Cal-33, 1483, UMSCC-22A). Cell viability was determined by MTT assay, and apoptosis by Annexin-V binding, FACS analysis and immunoblotting. All four HNSCC cell lines were highly sensitive to single agent obatoclax with IC50’s ranging from 50-300 nM. Obatoclax induced apoptosis in all four HNSCC cell lines as evidenced by increased Annexin-V binding at 48 hours from 10% in vehicle treated cells to 30-60% and through cleavage of caspase 3 and PARP. Interestingly, obatoclax enhanced the activity of the two small tyrosine kinase inhibitors of EGFR (erlotinib and gefitinib). We are the first to show the activity of obatoclax in HNSCC alone and in combination with EGFR inhibitors. In vivo study of obatoclax using human HNSCC xenograft tumors is currently underway. This preclinical study suggests that obatoclax might have a therapeutic role in HNSCC either alone or in combination with EGFR inhibitors.

Citation Format: Victor Y. Yazbeck, Kathleen Dorritie, Changyou Li, Jennifer Grandis, Yan Zang, Daniel E. Johnson. Obatoclax (GX15-070) potently induces apoptosis in head and neck squamous cell carcinoma (HNSCC) cell lines and enhances the activity of EGFR inhibitors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2439. doi:10.1158/1538-7445.AM2013-2439

Spontaneous transformation of murine epithelial cells requires the early acquisition of specific chromosomal aneuploidies and genomic imbalances

Human carcinomas are defined by recurrent chromosomal aneuploidies, which result in a tissue-specific distribution of genomic imbalances. In order to develop models for these genome mutations and to determine their role in tumorigenesis, we generated 45 spontaneously transformed murine cell lines from normal epithelial cells derived from bladder, cervix, colon, kidney, lung, and mammary gland. Phenotypic changes, chromosomal aberrations, centrosome number, and telomerase activity were assayed in control uncultured cells and in three subsequent stages of transformation. Supernumerary centrosomes, binucleate cells, and tetraploidy were observed as early as 48 hr after explantation. In addition, telomerase activity increased throughout progression. Live-cell imaging revealed that failure of cytokinesis, not cell fusion, promoted genome duplication. Spectral karyotyping demonstrated that aneuploidy preceded immortalization, consisting predominantly of whole chromosome losses (4, 9, 12, 13, 16, and Y) and gains (1, 10, 15, and 19). After transformation, focal amplifications of the oncogenes Myc and Mdm2 were frequently detected. Fifty percent of the transformed lines resulted in tumors on injection into immunocompromised mice. The phenotypic and genomic alterations observed in spontaneously transformed murine epithelial cells recapitulated the aberration pattern observed during human carcinogenesis. The dominant aberration of these cell lines was the presence of specific chromosomal aneuploidies. We propose that our newly derived cancer models will be useful tools to dissect the sequential steps of genome mutations during malignant transformation, and also to identify cancer-specific genes, signaling pathways, and the role of chromosomal instability in this process.

Advanced molecular cytogenetics in human and mouse

Fluorescence in situ hybridization, spectral karyotyping, multiplex fluorescence in situ hybridization, comparative genomic hybridization, and more recently array comparative genomic hybridization, represent advancements in the field of molecular cytogenetics. The application of these techniques for the analysis of specimens from humans, or mouse models of human diseases, enables one to reliably identify and characterize complex chromosomal rearrangements resulting in alterations of the genome. As each of these techniques has advantages and limitations, a comprehensive analysis of cytogenetic aberrations can be accomplished through the utilization of a combination approach. As such, analyses of specific tumor types have proven invaluable in the identification of new tumor-specific chromosomal aberrations and imbalances (aneuploidy), as well as regions containing tumor-specific gene targets. Application of these techniques has already improved the classification of tumors into distinct categories, with the hope that this will lead to more tailored treatment strategies. These techniques, in particular the application of tumor-specific fluorescence in situ hybridization probes to interphase nuclei, are also powerful tools for the early identification of premalignant lesions.