What hides behind the MASC: clinical response and acquired resistance to entrectinib after ETV6-NTRK3 identification in a mammary analogue secretory carcinoma (MASC).

BACKGROUND: Mammary analogue secretory carcinoma (MASC) is a recently described pathologic entity. We report the case of a patient with an initial diagnosis of salivary acinic cell carcinoma later reclassified as MASC after next-generation sequencing revealed an ETV6-NTRK3 fusion. PATIENTS AND METHODS: This alteration was targeted with the pan-Trk inhibitor entrectinib (Ignyta), which possesses potent in vitro activity against cell lines containing various NTRK1/2/3 fusions. RESULTS: A dramatic and durable response was achieved with entrectinib in this patient, followed by acquired resistance that correlated with the appearance of a novel NTRK3 G623R mutation. Structural modeling predicts that this alteration sterically interferes with drug binding, correlating to decreased sensitivity to drug inhibition observed in cell-based assays. CONCLUSIONS: This first report of clinical activity with TrkC inhibition and the development of acquired resistance in an NTRK3-rearranged cancer emphasize the utility of comprehensive molecular profiling and targeted therapy for rare malignancies (NCT02097810).

VMAT1 deletion causes neuronal loss in the hippocampus and neurocognitive deficits in spatial discrimination.

Vesicular monoamine transporters (VMAT) are involved in presynaptic storage and release of neurotransmitters. While it was thought initially that only VMAT2 is brain expressed and VMAT1 is present only in the periphery, recent data have challenged the exclusive expression of VMAT2 in the brain. To further elucidate the role of VMAT1 brain expression and its potential role in neuropsychiatric disorders, we have investigated mice lacking VMAT1. Comparison of wildtype and knock-out (KO) mice using qPCR and immunohistochemistry documents the expression of VMAT1 in the brain. Deletion of VMAT1 leads to increased hippocampal apoptosis and reduced neurogenesis as assessed by caspase-3-labeling and 5-bromo-deoxy-uridine-labeling. Behavioral data show that mice lacking VMAT1 have neurocognitive deficits. VMAT2 expression is not altered in VMAT1 KO mice, suggesting a distinct role of VMAT1. Our data support VMAT1 brain expression and suggest that VMAT1 plays a key role in survival of hippocampal neurons and thus might contribute to neurocognitive deficits observed in neuropsychiatric disorders.

Serotonin receptor 2A (HTR2A) gene polymorphism predicts treatment response to venlafaxine XR in generalized anxiety disorder.

Generalized anxiety disorder (GAD) is a chronic psychiatric disorder with significant morbidity and mortality. Antidepressant drugs are the preferred choice for treatment; however, treatment response is often variable. Several studies in major depression have implicated a role of the serotonin receptor gene (HTR2A) in treatment response to antidepressants. We tested the hypothesis that the genetic polymorphism rs7997012 in the HTR2A gene predicts treatment outcome in GAD patients treated with venlafaxine XR. Treatment response was assessed in 156 patients that participated in a 6-month open-label clinical trial of venlafaxine XR for GAD. Primary analysis included Hamilton Anxiety Scale (HAM-A) reduction at 6 months. Secondary outcome measure was the Clinical Global Impression of Improvement (CGI-I) score at 6 months. Genotype and allele frequencies were compared between groups using χ(2) contingency analysis. The frequency of the G-allele differed significantly between responders (70%) and nonresponders (56%) at 6 months (P=0.05) using the HAM-A scale as outcome measure. Similarly, using the CGI-I as outcome, the G-allele was significantly associated with improvement (P=0.01). Assuming a dominant effect of the G-allele, improvement differed significantly between groups (P=0.001, odds ratio=4.72). Similar trends were observed for remission although not statistically significant. We show for the first time a pharmacogenetic effect of the HTR2A rs7997012 variant in anxiety disorders, suggesting that pharmacogenetic effects cross diagnostic categories. Our data document that individuals with the HTR2A rs7997012 single nucleotide polymorphism G-allele have better treatment outcome over time. Future studies with larger sample sizes are necessary to further characterize this effect in treatment response to antidepressants in GAD.

Development of radioimmunotherapy for the treatment of non-Hodgkin's lymphoma.

The goal of radioimmunotherapy (RIT) is to target radiation to tumor tissue with radiolabeled monoclonal antibodies while limiting toxicity to normal cells. Radionuclide emission properties and the chemical stability of radioimmunoconjugates are important factors that contribute to the effectiveness of RIT. A 1994 review of early clinical trials with RIT in treating non-Hodgkin's lymphoma (NHL) reported a 40% response rate with nonmyeloablative doses of yttrium 90 (90Y) or iodine 131 (131I) antibodies. Of the radiolabeled antibodies currently in pivotal trials or approved by the US Food and Drug Administration, those targeted to the CD20 antigen have produced the highest response rates. Response rates for ibritumomab tiuxetan, the recently approved RIT for NHL, ranged from 74% in rituximab-refractory patients to 80% in the pivotal trial. The iodine-labeled anti-B1 antibody has been evaluated in previously treated and previously untreated patients with NHL. In the pivotal trial, previously treated patients achieved a response rate of 65%, whereas previously untreated patients had a 97% response rate. Radiolabeled anti-HLA DR has been evaluated in NHL patients and has demonstrated a 53% response rate. Murine antibody LL2, which recognizes the CD22 antigen, has been radiolabeled with 90Y and 131I, with response rates ranging from 15% to 33%. The development of radioimmunotherapy has led to meaningful advances in the treatment of B-cell NHL.

Secondary acute myelogenous leukemia with MLL gene rearrangement following radioimmunotherapy (RAIT) for non-Hodgkin's lymphoma.

Targeted therapy with conjugated and unconjugated monoclonal antibodies for non-Hodgkin's lymphoma has revolutionized the approach to this disease. The efficacy and low toxicity of these agents have allowed introduction of this strategy in the early stages of therapy. Longer follow-up is needed before validating the safety of these agents. Since monoclonal antibodies are being given as front-line therapy, it is important to identify all potential adverse events. We report a case of secondary acute myelogenous leukemia (AML) with 11q23 cytogenetic abnormality and mixed lymphoid leukemia (MLL) gene expression in a patient treated with Y90 labeled anti-CD20 antibody (Zevalin). The patient was not exposed to topoisomerase II inhibitors. Our observations suggest a relationship between 11q23 leukemia and radioimmunotherapy (RAIT) and further studies are needed.

Non-Hodgkin's lymphoma: review of conventional treatments.

The non-Hodgkin's lymphomas are a diverse groups of lymphoid neoplasms that collectively rank fifth in cancer incidence and mortality. Conventional treatment for patients with newly-diagnosed non-Hodgkin's lymphoma (NHL) includes radiation or chemotherapy. In addition, those with asymptomatic low-grade disease may follow a "watch and wait" approach. Single agent oral alkylating therapy and CVP (cyclophosphamide, vincristine, and prednisone) have become a mainstay of treatment for low-grade NHL. High intensity chemotherapy consisting of the anthracycline, doxorubicin along with cyclophosphamide, vincristine and prednisone (CHOP) is offered as standard treatment for intermediate-grade NHL. Following relapse, salvage therapy rarely results in long-term survival in patients with low-grade NHL. Up to 50% of patients die within five years of first relapse. For patients with intermediate-grade NHL who relapse after or do not respond to first-line treatment, a range of combination regimens can be offered, composed of non-cross resistant drugs not typically used during first-line treatment. However, less than half of patients with intermediate-grade disease achieve prolonged disease-free survival. With today's' conventional treatments, cure is only a possibility for a minority of patients with intermediate-grade disease and a limited group of patients with indolent NHL who are diagnosed at early stages. Novel approaches to treatment are therefore needed. Monoclonal antibodies may fulfill this need, administered either as single agents or in conjunction with conventional cytotoxic approaches. The task now lies in determining how best to use this new modality, with the hope of bringing a cure to a greater number of patients.

Monoclonal antibodies: a new era in the treatment of non-Hodgkin's lymphoma.

Monoclonal antibodies (MAbs) have been used as therapeutic agents for many years. In 1997, Rituxan (IDEC-C2B8, rituximab, MabThera) became the first MAb to be approved by the FDA for a cancer indication. Rituxan served to heighten interest in the therapeutic applications of MAbs. Herceptin (for patients with breast cancer) and Mylotarg (for patients with acute myeloid leukemia) were approved shortly thereafter. Literally dozens of antibodies are currently under investigation for a variety of malignant and non-neoplastic indications. Rituxan is effective in patients with low-grade or follicular, relapsed or refractory non-Hodgkin's lymphoma (NHL). The response rate and time to progression (responders) are in the 50% and 13 months range, respectively. It is also active in intermediate-grade NHL where a large randomized study, in combination with CHOP chemotherapy, has shown a statistically significant increase in complete response (CR) rate (75% vs. 60%), prolongation of 1 year event-free survival (69% vs. 49%) and of overall survival (83% vs. 68%) as compared to CHOP alone. This marks the first time that any agent has shown results superior to CHOP, the curative gold standard for this type of NHL. Other promising antibodies under clinical investigation include: Hu1D10; Anti CD19, 22, 52, and anti-Id antibodies. The safety profile, clinical activity, and mechanism of action of these MAbs make them ideal candidates for combination with chemotherapy or biologicals. Over the next few years, we will see very significant therapeutic advances emerge as this important research yields additional clinical results.

Intentional induction of mixed chimerism and achievement of antitumor responses after nonmyeloablative conditioning therapy and HLA-matched donor bone marrow transplantation for refractory hematologic malignancies.

Mixed lymphohematopoietic chimerism can be induced in mice with bone marrow transplantation (BMT) after a nonmyeloablative preparative regimen that includes cyclophosphamide, anti-T-cell antibody therapy, and thymic irradiation. These mixed chimeras are resistant to the induction of graft-versus-host disease (GVHD) after delayed donor leukocyte infusions (DLIs), despite a potent lymphohematopoietic graft-versus-host reaction that converts the mixed chimeric state to a full donor one. Based on this animal model, we initiated a trial of nonmyeloablative therapy with HLA-matched or -mismatched donor BMT and DLI for refractory hematologic malignancies. Twenty-one of 36 patients enrolled in this trial received a genotypically (n = 20) or phenotypically (n = 1) HLA-matched donor transplant; results reported here are for those patients only. Preparative therapy consisted of cyclophosphamide in doses of 150 to 200 mg/kg; peritransplant antithymocyte globulin; thymic irradiation (in patients who had not received previous mediastinal radiation therapy); and cyclosporine. Eighteen of 20 evaluable patients developed persistent mixed lymphohematopoietic chimerism as defined by >1% donor peripheral white blood cells until at least day 35 posttransplantation. Ten patients received prophylactic DLI beginning 5 to 6 weeks after BMT for conversion of mixed chimerism to full donor hematopoiesis and to optimize a graft-versus-leukemia effect. Fourteen of 20 evaluable patients (70%) achieved an antitumor response; 8 of these responses were complete, and 6 were partial. Of the 8 evaluable patients who received prophylactic DLI, 6 showed conversion to full donor chimerism. Five of the 9 evaluable patients (56%) who received prophylactic DLI achieved a complete response, compared with 3 of 11 patients (27%) who did not receive prophylactic DLI. Currently 11 patients are alive, and 7 of these are free of disease progression at a median follow-up time of 445 days (range, 105-548 days) posttransplantation. Transplantation-related complications included cyclophosphamide-induced cardiac toxicity in 3 of 21 patients (14%) and grade II or greater GVHD in 6 patients (29%). One patient (5%) died from a complication of BMT, and 1 patient (5%) died from GVHD after 2 prophylactic DLIs were given for conversion of chimerism. In summary, mixed lymphohematopoietic chimerism was reproducibly induced after a novel nonmyeloablative preparative regimen incorporating chemotherapy, peritransplant antithymocyte globulin, and thymic irradiation, allowing for early administration of DLI in 10 of 21 patients. After treatment, striking antitumor responses were observed in the majority of patients with chemotherapy-refractory hematologic malignancies.

High-dose cyclophosphamide + carboplatin and interleukin-2 (IL-2) activated autologous stem cell transplantation followed by maintenance IL-2 therapy in metastatic breast carcinoma - a phase II study.

While high-dose chemotherapy and stem cell transplantation is associated with higher complete response rates than conventional chemotherapy in patients with metastatic breast cancer (MBC), its role in conferring a survival advantage is unproven. We report the results of a prospective phase II trial of 33 patients accrued between 1996 to 1998 with chemosensitive MBC, who received cyclophosphamide (Cy) 2000 mg/m2/day and carboplatin (Cb) 600 mg/m2/day for 3 consecutive days, followed by infusion of peripheral blood stem cells cultured in IL-2 for 24 h on day 0 as adoptive immunotherapy. Low-dose interleukin-2 (IL-2) was administered from day 0 to +4 and/or +7 to +11, +14 to +18, +21 to +25, then 5 days per month for 11 months to augment a graft-versus-tumor effect. The results of this study were compared to those of a historical control group treated with an identical high-dose Cb + Cy regimen with SCT but without IL-2 treatment. Only gastrointestinal (GI) toxicity was more frequent in the IL-2 cohort (P = 0.0031). At a median follow-up of 18.6 months, the median progression-free survival (PFS) is 9 months (2.4-40) and the median OS has not been reached yet. The Kaplan-Meier estimated 2 year PFS is 35%, compared with 17% in the control arm (P = 0.73), and the estimated 2 year OS is 78%, compared with 61% in the control arm (P = 0.22). Multivariate analysis showed that ER status was an independent predictor for OS and PFS, and less chemotherapy prior to HDCSCT predicted for a better PFS. These results show that augmenting HDC with IL-2 activated SCT is well-tolerated. Whether a therapeutic advantage is achievable in patients with MBC remains to be determined. Bone Marrow Transplantation (2000) 25, 19-24.

A Phase II study of adjuvant therapy with anti-B4-blocked ricin after autologous bone marrow transplantation for patients with relapsed B-cell non-Hodgkin's lymphoma.

This Phase II trial was undertaken to determine the safety, toxicity, and potential efficacy of the B-cell restricted immunotoxin anti-B4-blocked ricin (Anti-B4-bR) when administered as adjuvant therapy to patients in complete remission (CR) after autologous bone marrow transplantation (ABMT) for B-cell non-Hodgkin's lymphoma (NHL). Forty-nine patients with B-cell NHL in CR 46-202 days (median, 112 days) post-ABMT received Anti-B4-bR at a dose of 30 microg/kg lean body weight/day for 7 days by continuous i.v. infusion. Patients were eligible for up to two additional courses of therapy at 14-day intervals. A total of 83 courses of Anti-B4-bR were administered, with 31 patients receiving two or more courses of therapy. The mean serum level on day 7 of the first course was 0.77+/-0.41 nM. Reversible toxicities included hepatic transaminase elevations, thrombocytopenia, myalgias, fatigue, nausea, hypoalbuminemia, and dyspnea. Human antimouse antibody (HAMA) and/or human antiricin antibody (HARA) responses occurred in 23 patients at a median of 22 days from the initiation of Anti-B4-bR therapy (range, 11-100 days). The 4-year disease-free survival and overall survival are estimated at 56 and 72%, respectively. Twenty-six patients remain in CR after a median follow-up of 54.5 months. This study demonstrates that Anti-B4-bR can be administered safely to patients as adjuvant therapy early after ABMT for B-cell NHL. The toxicities are tolerable and reversible. Although the early estimate of disease-free survival was very encouraging in this single-armed trial, the 4-year follow-up data demonstrate continued relapse.

Melanoma.

In melanoma, conventional therapies, especially cytotoxic chemotherapies, have proven unsatisfactory. Although a variety of agents have been tested singly and in combination, recent randomized studies have demonstrated that the response rates observed in single institution phase II trials are not generalizable to multi-institution settings. Studies of cytokine therapy, especially interferon-alpha in the adjuvant situation, and interleukin-2 for advanced disease, have demonstrated some utility to these agents. However, their toxicities remain formidable, and studies refining their use are under way. The limited successes of such immunomodulatory strategies have provided a rationale for continued pursuit of immunotherapy approaches. It is likely that in the near future such active immunization protocols will continue to be actively investigated.

Monoclonal antibody-based therapies for hematologic malignancies.

PURPOSE: To review recent advances in the development and clinical roles of monoclonal antibody (MoAb)-based therapies in the treatment of hematologic malignancies. DESIGN: A search of MEDLINE and CANCERLIT was conducted to identify relevant publications. The bibliographies of these references also were used to identify articles and abstracts. These references were then reviewed. RESULTS: In the two decades since the first patient was treated with MoAb therapy, there have been significant advances in the biology, pharmacology, and clinical application of MoAb-based therapies. Three distinct fields of research have emerged: unconjugated MoAbs, immunotoxin-conjugated MoAbs (ITs), and radionuclide-conjugated MoAbs (RICs). The unconjugated MoAbs are less toxic but depend on host mechanisms to mediate cytotoxicity. The ITs carry a potent toxin, although at the cost of a narrow therapeutic index that may limit clinical use. The RICs offer significant potency, even in refractory disease, but their complexity may limit their use to large cancer centers. The current challenges in the development of MoAb-based therapies are to identify the proper target antigens, contend with bulk disease in which penetration may be limited, and choose the optimal clinical settings for their use, such as the minimal residual disease state or in combination with conventional chemotherapy. CONCLUSION: Although significant research is still needed, MoAb-based therapies promise to offer new options for the treatment of patients with hematologic malignancies.

Phase II clinical trial of bolus infusion anti-B4 blocked ricin immunoconjugate in patients with relapsed B-cell non-Hodgkin's lymphoma.

Immunotoxins, composed of a monoclonal antibody conjugated to a protein toxin, mediate cell death through novel cytotoxic mechanisms. Anti-B4-blocked ricin (anti-B4-bR) recognizes CD19-positive cells, which includes most B-cell non-Hodgkin's lymphomas (NHLs). Previous Phase I clinical studies of anti-B4-bR, using both bolus and continuous dosing regimens, demonstrated no safety or efficacy advantage to the continuous infusion regimen. This Phase II trial in 16 patients with relapsed CD19-positive NHL was conducted to evaluate the efficacy of anti-B4-bR when administered at the previously established maximum tolerated dose using a daily bolus for a 5 consecutive days schedule. Serum pharmacokinetics were measured in selected patients. Tissue samples of involved lymph nodes and bone marrow were also obtained from a portion of patients for determination of anti-B4-bR penetration into tissues. Toxicity was similar to what has been described previously for anti-B4-bR and consisted mainly of reversible elevations of hepatic transaminases and mild to moderate thrombocytopenia. No sustained clinical responses were documented. Pharmacokinetic measurements demonstrated that serum levels compatible with 3 logs of cell kill in vitro could be sustained for several hours in most patients. Immunohistochemical analysis of tissue samples provided some insight into the low efficacy. The immunotoxin could be detected in three of the four bone marrow aspirate samples but in only two of the seven lymph node specimens. Thus, anti-B4-bR, using a single daily bolus for a 5 consecutive day schedule, is not an active agent in relapsed NHL. Poor penetration into certain sites of disease may be one explanation for its lack of efficacy.

Translational research: walking the bridge between idea and cure--seventeenth Bruce F. Cain Memorial Award lecture.

Advances in the understanding of normal and malignant cell biology are allowing the development of biologically targeted drugs directed at specific differences between host and tumor. The array of potential new targets is vast, but drugs currently in development are targeted at cell-cycle regulators, growth factors and their receptors, signal transduction intermediates, angiogenesis, and the mechanisms that mediate apoptosis and DNA repair. Recent results raise the possibility that novel biologically targeted agents, perhaps in combination with traditional cytotoxic agents, may finally cure cancer. However, the development of a biologically targeted drug raises unique challenges in the design of clinical trials to demonstrate its efficacy, and despite the promising preclinical data that exist for most of the agents in development, the clinical trial remains the critical, final step across the bridge from basic research to clinical application. In this review, we discuss some of the challenges in the clinical development of biologically targeted agents and the implications for clinical trial design.

Neocortical dendritic pathology in human partial epilepsy: a quantitative Golgi study.

We used a computerized image-analysis system to perform a quantitative analysis of rapid Golgi-impregnated pyramidal neurons of the third cortical layer of histologically normal cerebral cortex surgically removed from patients with partial epilepsy. Various parameters of 51 neurons from 9 patients and 29 neurons from 5 age-matched controls were compared. Dendritic spine density decreased progressively with increasing duration of seizures, and dendritic swellings were most numerous in epilepsy cases of uncertain etiology and in patients with seizures of longer standing. Neurons from seizure cases showed fewer dendritic branching points and fewer proximal dendritic branches than those from controls, suggesting a simplified dendritic architecture. These findings indicate that neurons in cortex distant from the primary site of epileptogenic activity may be undergoing subtle, progressive degeneration, which may explain the propensity of chronic epilepsy patients to have increased seizure activity and interictal behavioral and cognitive aberrations.