Christos Vaklavas

Anti-Vascular Endothelial Growth Factor Therapies and Cardiovascular Toxicity: What Are the Important Clinical Markers to Target?

BACKGROUND Therapies targeting vascular endothelial growth factor (VEGF) are associated with hypertension, cardiotoxicity, and thromboembolic events. METHODS All prospective phase I-III clinical trials published up to December 2008 of approved anti-VEGF therapies (bevacizumab, sunitinib, sorafenib) and relevant literature were reviewed. RESULTS The rates of Common Toxicity Criteria (version 3) grade 3-4 hypertension with bevacizumab, sunitinib, and sorafenib were 9.2%, 6.9%, and 7.2%, respectively. Grade 3-4 left ventricular systolic dysfunction was noted in 0.3%, 1.4%, and 0.05% of patients, respectively, whereas the rates of grade 3-4 thromboembolism were 9.6%, 1.2%, and 3.8%, respectively. The renin-angiotensin-aldosterone system (RAAS) may play a key role in vasoconstriction and capillary rarefaction, which are unleashed when VEGF signaling is targeted. Inhibiting RAAS may be the optimal approach for managing these toxicities. CONCLUSIONS In anticipation of cardiovascular complications with anti-VEGF therapies, early detection and personalized management may improve clinical outcomes and tolerance.

Safety and efficacy of brentuximab vedotin in patients with Hodgkin lymphoma or systemic anaplastic large cell lymphoma

Antibody-based immunotherapy has become an integral part of cancer therapeutics. However, monoclonal antibodies have their limitations as identifying an antigen selectively expressed on malignant cells and developing a high-affinity antibody may not by itself alter tumor growth. This is illustrated in the case of CD30; CD30 epitomizes many properties of an ideal pharmacologic target such as high expression on malignant cells and limited expression on normal tissues. However, until the advent of brentuximab vedotin, CD30 remained an elusive target as antibody-based anti-CD30 immunotherapy had been largely clinically unsuccessful. Brentuximab vedotin (cAC10-vcMMAE, SGN-35) is an antibody-drug conjugate consisting of a chimeric anti-CD30 monoclonal antibody whereupon the potent microtubule inhibitor monomethyl auristatin E (MMAE) is attached via a valine–citrulline linker. Once bound to CD30, brentuximab vedotin is internalized and MMAE is released with the action of lysosomal enzymes on the linker. In phase I studies in relapsed or refractory Hodgkin lymphoma and anaplastic large cell lymphoma, brentuximab vedotin induced unprecedented responses with manageable toxicity. In phase II studies, brentuximab vedotin induced overall response rates of 75% and 86% in relapsed or refractory Hodgkin lymphoma and anaplastic large cell lymphoma, respectively. The results of these trials led to the accelerated approval of the drug by the US Food and Drug Administration in a patient population with few other alternative options. Brentuximab vedotin has overall manageable toxicity profile; however, cumulative peripheral neuropathy constitutes an important clinical consideration as it may limit prolonged administration of the drug. The mechanism by which brentuximab vedotin exerts its antitumor activity is not entirely clear. Diffusion of MMAE in the tumor microenvironment and cytotoxicity on bystander cells may in part explain its activity, especially in Hodgkin lymphoma. Herein, we review the biology of CD30 and brentuximab vedotin, and the clinical data that has accumulated thus far with SGN-35.

Inhibition of the fibroblast growth factor receptor (FGFR) pathway: the current landscape and barriers to clinical application

The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) is a tyrosine kinase signaling pathway that has a fundamental role in many biologic processes including embryonic development, tissue regeneration, and angiogenesis. Increasing evidence indicates that this pathway plays a critical role in oncogenesis via gene amplification, activating mutations, or translocation in tumors of various histologies. With multiplex sequencing technology, the detection of FGFR aberrations has become more common and is tied to cancer cell proliferation, resistance to anticancer therapies, and neoangiogenesis. Inhibition of FGFR signaling appears promising in preclinical studies, suggesting a pathway of clinical interest in the development of targeted therapy. Phase I trials have demonstrated a manageable toxicity profile. Currently, there are multiple FGFR inhibitors under study with many non-selective (multi-kinase) inhibitors demonstrating limited clinical responses. As we progress from the first generation of non-selective drugs to the second generation of selective FGFR inhibitors, it is clear that FGFR aberrations do not behave uniformly across cancer types; thus, a deeper understanding of biomarker strategies is undoubtedly warranted. This review aims to consolidate data from recent clinical trials with a focus on selective FGFR inhibitors. As Phase II clinical trials emerge, concentration on patient selection as it pertains to predicting response to therapy, feasible methods for overcoming toxicity, and the likelihood of combination therapies should be utilized. We will also discuss qualities that may be desirable in future generations of FGFR inhibitors, with the hope that overcoming these current barriers will expedite the availability of this novel class of medications.

Validation of the royal marsden hospital prognostic score in patients treated in the phase I clinical trials program at the MD Anderson Cancer Center

The authors validated the Royal Marsden Hospital (RMH) prognostic score in patients with advanced lung, pancreatic, and head and neck cancers who were enrolled on phase 1 trials in the MD Anderson Cancer Center Phase I Clinical Trials Program.

Dasatinib Inhibits the Growth of Molecularly Heterogeneous Myeloid Leukemias

Purpose: Dasatinib is a dual Src/Abl inhibitor recently approved for Bcr-Abl+ leukemias with resistance or intolerance to prior therapy. Because Src kinases contribute to multiple blood cell functions by triggering a variety of signaling pathways, we hypothesized that their molecular targeting might lead to growth inhibition in acute myeloid leukemia (AML). Experimental Design: We studied growth factor–dependent and growth factor–independent leukemic cell lines, including three cell lines expressing mutants of receptor tyrosine kinases (Flt3 or c-Kit) as well as primary AML blasts for responsiveness to dasatinib. Results: Dasatinib resulted in the inhibition of Src family kinases in all cell lines and blast cells at ∼1 × 10−9 mol/L. It also inhibited mutant Flt3 or Kit tyrosine phosphorylation at ∼1 × 10−6 mol/L. Mo7e cells expressing the activating mutation (codon 816) of c-Kit were most sensitive to growth inhibition with a GI50 of 5 × 10−9 mol/L. Primary AML blast cells exhibited a growth inhibition of <1 × 10−6 mol/L. Cell lines that showed growth inhibition at ∼1 × 10−6 mol/L showed a G1 cell cycle arrest and correlated with accumulation of p21 and p27 protein. The addition of rapamycin or cytotoxic agents enhanced growth inhibition. Dasatinib also caused the apoptosis of Mo7e cells expressing oncogenic Kit. Conclusions: Although all of the precise targets for dasatinib are not known, this multikinase inhibitor causes either growth arrest or apoptosis in molecularly heterogeneous AML. The addition of cytotoxic or targeted agents can enhance its effects. Clin Cancer Res; 16(4); 1149–58

Common cardiovascular medications in cancer therapeutics

Cardiac glycosides, statins, β-blockers, angiotensin-I converting enzyme inhibitors (ACEIs), and angiotensin II type 1 receptor blockers (ARBs) are widely used cardiovascular medications with pleiotropic properties. Many of these medications have been investigated in other diseases, including cancer. Cardiac glycosides and statins have advanced to clinical trial testing in cancer therapeutics, with variable success. Early observations in breast cancer were consistent with a more benign histologic phenotype among women taking digitalis compared to their counterparts who did not receive cardiac glycosides. Cardiac glycosides can induce apoptosis in cancer cells through various mechanisms and sensitize them to the effects of antitumor therapy. By blocking the generation of prenyl units, statins impair prenylation, an important posttranslational modification of proteins whose function depends on membrane anchoring. Statins also impair protein folding and N-glycosylation and inhibit the upregulation of cholesterol synthesis associated with chemotherapy resistance. Stress and catecholamine release promote tumor growth and angiogenesis, effects that can be mitigated by β-blockers. Components of the renin-angiotensin-aldosterone system are expressed in various cancers and are involved in carcinogenesis and tumor progression. Angiotensin II has potent mitogenic and angiogenic properties that can be blocked with ACEIs and ARBs. Although it is unclear whether the promising preclinical activity of many cardiovascular medications has clinically meaningful implications beyond the benefit in cardiovascular morbidity and mortality, the prevention or improvement of prognosis of common malignancies with medications known to reduce cardiovascular morbidity and mortality is encouraging and deserves further clinical investigation.

Pediatric therapy-related myelodysplastic syndrome/acute myeloid leukemia: The MD anderson cancer center experience

Therapy-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/AML) is a long-term complication of pediatric cancer. We retrospectively studied pediatric t-MDS/AML patients treated at MD Anderson from 1975 to 2007. We also compared those patients to pediatric patients with de novo MDS/AML during this time interval. Among 2589 children with cancer treated at MD Anderson, we identified 22 patients with t-MDS/AML. Patients with t-MDS/AML had a median age of 14 years. There was a male and Hispanic predominance. The most common primary malignancies were osteosarcoma and Hodgkin lymphoma. The median latency period was 4.1 years. Three patients received supportive care only. Group 1 (n=5) underwent stem cell transplantation without induction chemotherapy. Group 2 (n=5) patients received AML-type chemotherapy and a stem cell transplant postremission (n=5). Group 3 (n=4) received a stem cell transplant as salvage therapy. The respective 2-year survival rates for groups 1, 2, and 3 were 20%, 40%, and 25% (P=0.85). Patients with de novo AML were younger (P=0.001) and higher rates of complete remission (P=0.03), and survival (P<0.0001). Independent factors predicting shorter survival were poor/intermediate-risk cytogenetics (P=0.01), lower hemoglobin level (P=0.0001), and t-MDS/AML (vs. de novo) (P=0.003). Childhood t-MDS/AML has a poor prognosis. Although patients benefited from AML-type induction chemotherapy followed by stem cell transplantation as postremission therapy, effective therapies, and prevention are needed.

Phase I Clinical Trials in 56 Patients with Thyroid Cancer: The M. D. Anderson Cancer Center Experience

INTRODUCTION Thyroid cancer is the most common endocrine malignancy. The outcomes of patients with relapsed thyroid cancer treated on early-phase clinical trials have not been systematically analyzed. PATIENTS AND METHODS We reviewed the records of consecutive patients with metastatic thyroid cancer referred to the Phase I Clinical Trials Program from March 2006 to April 2008. Best response was assessed by Response Evaluation Criteria in Solid Tumors. RESULTS Fifty-six patients were identified. The median age was 55 yr (range 35-79 yr). Of 49 patients evaluable for response, nine (18.4%) had a partial response, and 16 (32.7%) had stable disease for 6 months or longer. The median progression-free survival was 1.12 yr. With a median follow-up of 15.6 months, the 1-yr survival rate was 81%. In univariate analysis, factors predicting shorter survival were anaplastic histology (P = 0.0002) and albumin levels less than 3.5 g/dl (P = 0.05). Among 26 patients with tumor decreases, none died (median follow-up 1.3 yr), whereas 52% of patients with any tumor increase died by 1 yr (P = 0.0001). The median time to failure in our phase I clinical trials was 11.5 months vs. 4.1 months for the previous treatment (P = 0.04). CONCLUSION Patients with advanced thyroid cancer treated on phase I clinical trials had high rates of partial response and prolonged stable disease. Time to failure was significantly longer on the first phase I trial compared with the prior conventional treatment. Patients with any tumor decrease had significantly longer survival than those with any tumor increase.

TBCRC 019: A Phase II Trial of Nanoparticle Albumin-Bound Paclitaxel with or without the Anti-Death Receptor 5 Monoclonal Antibody Tigatuzumab in Patients with Triple-Negative Breast Cancer

Purpose: Tigatuzumab (TIG), an agonistic anti-DR5 antibody, triggers apoptosis in DR5+ human tumor cells without crosslinking. TIG has strong in vitro/in vivo activity against basal-like breast cancer cells enhanced by chemotherapy agents. This study evaluates activity of TIG and chemotherapy in patients with metastatic triple-negative breast cancer (TNBC). Experimental Design: Randomized 2:1 phase II trial of albumin-bound paclitaxel (nab-PAC) ± TIG in patients with TNBC stratified by prior chemotherapy. Patients received nab-PAC weekly × 3 ± TIG every other week, every 28 days. Primary objective was within-arm objective response rate (ORR). Secondary objectives were safety, progression-free survival (PFS), clinical benefit, and TIG immunogenicity. Metastatic research biopsies were required. Results: Among 64 patients (60 treated; TIG/nab-PAC n = 39 and nab-PAC n = 21), there were 3 complete remissions (CR), 8 partial remissions (PR; 1 almost CR), 11 stable diseases (SD), and 17 progressive diseases (PD) in the TIG/nab-PAC arm (ORR, 28%), and no CRs, 8 PRs, 4 SDs, and 9 PDs in the nab-PAC arm (ORR, 38%). There was a numerical increase in CRs and several patients had prolonged PFS (1,025+, 781, 672, 460, 334) in the TIG/nab-PAC arm. Grade 3 toxicities were 28% and 29%, respectively, with no grade 4–5. Exploratory analysis suggests an association of ROCK1 gene pathway activation with efficacy in the TIG/nab-PAC arm. Conclusions: ORR and PFS were similar in both. Preclinical activity of TIG in basal-like breast cancer and prolonged PFS in few patients in the combination arm support further investigation of anti-DR5 agents. ROCK pathway activation merits further evaluation. Clin Cancer Res; 21(12); 2722–9. ©2015 AACR. See related article by Paoletti et al., p. 2771

Progressive multifocal leukoencephalopathy in a patient without apparent immunosuppression

An 80-year-old man with no history of an immune-compromising disorder was diagnosed with progressive multifocal leukoencephalopathy (PML). He presented with dysphagia and left-sided weakness; magnetic resonance imaging demonstrated marked signal abnormality in the subcortical white matter of the left frontal lobe and in the posterior limb of the right internal capsule. Polymerase chain reaction (PCR) analysis of the cerebrospinal fluid (CSF) was negative for John Cunningham (JC) virus. On brain biopsy, foamy macrophages infiltrating the white matter were identified, staining positive for anti-simian virus 40 antibodies. Postoperatively, PCR for JC viral DNA in the CSF was positive, establishing the diagnosis of PML. Extensive investigation for an occult immunocompromising disorder was negative. The patients neurologic deficits rapidly increased throughout his hospital stay, and he died 3.5 months after his diagnosis.