Mauricio Burotto

Gefitinib and Erlotinib in Metastatic Non-Small Cell Lung Cancer: A Meta-Analysis of Toxicity and Efficacy of Randomized Clinical Trials

BACKGROUND Tyrosine kinase inhibitors (TKIs) targeting the epidermal growth factor receptor (EGFR) have been evaluated in patients with metastatic and advanced non-small cell lung cancer (NSCLC). The U.S. Food and Drug Administration initially granted accelerated approval to gefitinib but subsequently rescinded the authorization. Erlotinib and afatinib are similar compounds approved for the treatment of metastatic NSCLC. The objective of this study was to compare the efficacy and toxicity of erlotinib, gefitinib, and afatinib in NSCLC. METHODS We tabulated efficacy variables including overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) and quantitated toxicities and rates of dose reductions and discontinuation. Summary odds ratios were calculated using random and fixed-effects models. An odds ratio was the summary measure used for pooling of studies. RESULTS We examined 28 studies including three randomized trials with afatinib. Clinical toxicities, including pruritus, rash, anorexia, diarrhea, nausea, fatigue, mucositis, paronychia, and anemia, were similar between erlotinib and gefitinib, although some statistical differences were observed. Afatinib treatment resulted in more diarrhea, rash, and paronychia compared with erlotinib and gefitinib. Regarding efficacy, similar outcomes were recorded for ORR, PFS, or OS in the total population and in specific subgroups of patients between erlotinib and gefitinib. All three TKIs demonstrated higher ORRs in first line in tumors harboring EGFR mutations. CONCLUSION Gefitinib has similar activity and toxicity compared with erlotinib and offers a valuable alternative to patients with NSCLC. Afatinib has similar efficacy compared with erlotinib and gefitinib in first-line treatment of tumors harboring EGFR mutations but may be associated with more toxicity, although further studies are needed. Gefitinib deserves consideration for U.S. marketing as a primary treatment for EGFR-mutant NSCLC.

Microtubule-targeting agents augment the toxicity of DNA-damaging agents by disrupting intracellular trafficking of DNA repair proteins

Significance Drugs targeting microtubules are among the most active anticancer agents. In vitro and in preclinical models, these agents are said to interfere with mitosis. However human tumors divide too slowly for this paradigm to apply, evidenced by the failure of over a dozen well-designed antimitotic agents targeting the aurora kinases and kinesin spindle protein that had minimal antitumor activity but caused severe bone marrow suppression. We have proposed that microtubule-targeting agents interfere with the trafficking of critical proteins in interphase microtubules. If true, then one must identify critical proteins whose traffic on microtubules is impacted. We identify nine DNA repair proteins that traffic on microtubules, explaining why combinations of a microtubule-targeting agent and a DNA-damaging agent are frequently used in cancer therapy. The paradigm that microtubule-targeting agents (MTAs) cause cell death via mitotic arrest applies to rapidly dividing cells but cannot explain MTA activity in slowly growing human cancers. Many preferred cancer regimens combine a MTA with a DNA-damaging agent (DDA). We hypothesized that MTAs synergize with DDAs by interfering with trafficking of DNA repair proteins on interphase microtubules. We investigated nine proteins involved in DNA repair: ATM, ATR, DNA-PK, Rad50, Mre11, p95/NBS1, p53, 53BP1, and p63. The proteins were sequestered in the cytoplasm by vincristine and paclitaxel but not by an aurora kinase inhibitor, colocalized with tubulin by confocal microscopy and coimmunoprecipitated with the microtubule motor dynein. Furthermore, adding MTAs to radiation, doxorubicin, or etoposide led to more sustained γ-H2AX levels. We conclude DNA damage-repair proteins traffic on microtubules and addition of MTAs sequesters them in the cytoplasm, explaining why MTA/DDA combinations are common anticancer regimens.

Bendamustine and rituximab in relapsed and refractory hairy cell leukemia.

Purpose: To determine tolerability and for the first time explore efficacy of bendamustine–rituximab (BR) in multiply relapsed/refractory hairy cell leukemia (HCL), using two different dose levels of bendamustine. Experimental Design: Patients with HCL with ≥2 prior therapies requiring treatment received rituximab 375 mg/m2 days 1 and 15 plus bendamustine 70 (n = 6) or 90 (n = 6) mg/m2, days 1 and 2, for six cycles at 4-week intervals. Results: At 70 and 90 mg/m2/dose of bendamustine, overall response rate was 100%, with three (50%) and four (67%) complete remissions (CR) in each respective group. Minimal residual disease (MRD) was absent in 67% and 100% of CRs, respectively. All six without MRD remain in CR at 30 to 35 (median, 31) months of follow-up. Soluble CD22 and CD25 levels decreased with all responses, with median values decreasing from 17.7 and 42 ng/mL at baseline to undetectable and 2 ng/mL after CR, respectively (P < 0.001). Of 12 patients receiving 72 cycles of BR, the most common toxicities were hematologic, including thrombocytopenia (83%), lymphopenia (75%), leukopenia (58%), and neutropenia (42%). Grade III and IV hematologic toxicity included lymphopenia and thrombocytopenia (each 75%), leukopenia (58%), and neutropenia (25%). No significant dose-related differences were detected in response or toxicity. Conclusion: BR has significant activity in HCL. Bendamustine at either 70 or 90 mg/m2/dose was highly effective in multiply relapsed/refractory HCL and could be considered for achieving durable CRs without MRD in patients after failure of standard therapies. As it was not dose-limiting, 90 mg/m2/dose was chosen for future testing. Clin Cancer Res; 19(22); 6313–21. ©2013 AACR.

Continuing a cancer treatment despite tumor growth may be valuable: sunitinib in renal cell carcinoma as example.

Background The US FDA and the EMA have approved seven agents for the treatment of renal cell carcinoma, primarily based on differences in progression-free survival (PFS). Because PFS is an arbitrary endpoint we hypothesized that an analysis would demonstrate the growth rate of tumors remained constant at the time of RECIST-defined disease progression. Methods We previously estimated the growth (g) and regression (d) rates and the stability of g using data from the Phase III trial comparing sunitinib and interferon. Results Sufficient data were available and rate constants statistically valid in 321 of 374 patients randomized to sunitinib. Median d was 0•0052 days−1; in 53 patients no tumor growth was recorded. Median g was 0•00082 days-1 and was stable for a median of 275 days on therapy, remaining stable beyond 300, 600 and 900 days in 122, 65 and 27 patients, respectively. A possible increase in g while receiving sunitinib could be discerned in only 18 of 321 patients. Given a median g of 0•00082 days−1 the estimated median time to a second progression were sunitinib continued past RECIST-defined progression was 7.3 months. At 100, 200, and 300 days after starting therapy, an estimated 47%, 27%, and 13% of tumor remains sunitinib sensitive and could explain a RECIST-defined response to a new TKI. Conclusion Prolonged stability of g with sunitinib suggests continued sunitinib beyond RECIST-defined progression may provide a beneficial outcome. Randomized trials in patients whose disease has “progressed” on sunitinib are needed to test this hypothesis.

Class act: safety comparison of approved tyrosine kinase inhibitors for non-small-cell lung carcinoma

Introduction: The past decade has seen the development and widespread use of tyrosine kinase inhibitors (TKIs) targeting a mutated EGFR (mEGFR) for the treatment of metastatic NSCLC. We discuss the main properties of the TKIs currently recommended for the treatment of mEGFR NSCLC: gefitinib, erlotinib and afatinib. Areas covered: The mechanism of action, pharmacodynamics and pharmacokinetics of these drugs, with emphasis on the historical context of their preclinical and clinical development, will be covered, including potential resistance mechanisms to these first-generation TKIs that has driven the trial design for second and third generations of EGFR inhibitors. Six Phase III clinical trials comparing these three TKIs with cisplatin-based chemotherapy upfront for mEGFR NSCLC provide the basis for the comparative safety and toxicity analysis between these agents. Class-related toxicity of these EGFR inhibitors, including life-threatening effects, will be discussed. Expert opinion: Toxicity and safety analysis from the Phase III trials of these agents in mEGFR populations suggests that afatinib has more frequent and severe side effects. Given that an efficacy advantage has not yet been demonstrated for afatinib over erlotinib and gefitinib, the consistent class toxicity profile of these agents means that gefitinib and erlotinib are a safer first-line treatment recommendation.

PPARγ in head and neck cancer prevention.

Head and neck cancer is a major source of morbidity and mortality worldwide. Intervention during the early phases of carcinogenesis represents a promising new strategy for curbing the devastating effects of this disease and its primary treatment modalities, surgery and radiation with or without concomitant chemotherapy. This review focuses on the peroxisome proliferator-activated receptor gamma (PPARγ) as a target for chemoprevention of oral cancer. Accumulating data suggest that ligands of PPARγ, which include the thiazolidinedione class of agents approved for the treatment of diabetes, inhibit cancer cell growth in vitro and in animal carcinogenesis models, providing the rationale for testing this approach in populations at risk for head and neck cancer.

Neutral evolution of drug resistant colorectal cancer cell populations is independent of their KRAS status

Emergence of tumor resistance to an anti-cancer therapy directed against a putative target raises several questions including: (1) do mutations in the target/pathway confer resistance? (2) Are these mutations pre-existing? (3) What is the relative fitness of cells with/without the mutation? We addressed these questions in patients with metastatic colorectal cancer (mCRC). We conducted an exhaustive review of published data to establish a median doubling time for CRCs and stained a cohort of CRCs to document mitotic indices. We analyzed published data and our own data to calculate rates of growth (g) and regression (d, decay) of tumors in patients with CRC correlating these results with the detection of circulating MT-KRAS DNA. Additionally we estimated mathematically the caloric burden of such tumors using data on mitotic and apoptotic indices. We conclude outgrowth of cells harboring intrinsic or acquired MT-KRAS cannot explain resistance to anti-EGFR (epidermal growth factor receptor) antibodies. Rates of tumor growth with panitumumab are unaffected by presence/absence of MT-KRAS. While MT-KRAS cells may be resistant to anti-EGFR antibodies, WT-KRAS cells also rapidly bypass this blockade suggesting inherent resistance mechanisms are responsible and a neutral evolution model is most appropriate. Using the above clinical data on tumor doubling times and mitotic and apoptotic indices we estimated the caloric intake required to support tumor growth and suggest it may explain in part cancer-associated cachexia.

Brain Metastasis in Patients With Adrenocortical Carcinoma: A Clinical Series

INTRODUCTION Adrenocortical carcinoma (ACC) is a heterogeneous and rare disease. At presentation or at the time of a recurrence, the disease commonly spreads to the liver, lungs, lymph nodes, and bones. The brain has only rarely been reported as a site of metastases. OBJECTIVE The aims of this report were to describe the clinical characteristics of patients with ACC who developed brain metastasis and were evaluated at the National Cancer Institute. METHODS We describe the history and clinical presentation of six patients with ACC and metastatic disease in the brain. Images of the six patients and pathology slides were reviewed when available. RESULTS The median age at the time of the diagnosis of ACC was 42 years. The median time from the initial diagnosis until the presentation of brain metastasis was 43 months. As a group the patients had previously received multiples lines of chemotherapy (median of three), and they presented with one to three metastatic brain lesions. Four patients underwent metastasectomy, one had radiosurgery, and one had both modalities. Two patients are still alive, three died, between 2 and 14 months after the diagnosis of brain metastases, and one was lost to follow-up. CONCLUSION Patients with advanced ACC can rarely present with metastasis to the brain, most often long after the initial diagnosis. Timely diagnosis of brain metastasis with appropriate intervention after discussion in a multidisciplinary meeting can improve the prognosis in this particular scenario.

Emphasizing unique strengths and eliminating redundancy for research in low‐income and middle‐income countries: Lessons from a South American country

INTRODUCTION Although lowand middle-income countries (LMIC) face countless challenges that high-income countries are spared, they still manage to make funding available for biomedical research and discovery. Data from the World Bank demonstrate that LMIC spend approximately 1.24% of their gross domestic product on research and development efforts. In contrast, high-income countries spend, on average, 2.32% of their gross domestic product on such efforts. Although these relative figures understate the absolute spending by nations, they do reflect the fact that LMIC consider research and discovery to be an integral part of their development plans. In addition to funds that LMIC devote to research, there is also an influx of foreign capital. For example, from 1995 to 2005, the Wellcome Trust spent millions on basic science research in vaccinology in LMIC. When it comes to biomedical research in LMIC, every dollar counts. For this reason, it is vital that research projects are prioritized, and redundant or wasteful research is eliminated. Using the example of Chile, a nation from which one of us hails (M.B.), and the research agenda of which we are familiar, we hope to highlight some potential areas of replicative research efforts, as well as identify exceptionally valuable and original efforts. These examples can provide guiding principles by which LMIC can set a highly productive research agenda.

Breast Cancer Staging: Is TNM Ready to Evolve?

The development of the TNM classification of malignant tumors has provided oncology with an invaluable tool for treatment decision making on the basis of cancer extent and spread. The TNM system is also essential for reliable outcome comparison of different interventions and accurate follow-up statistics. Therefore, it is currently the structural framework for prognosis description and determining the likelihood of successful outcomes for different treatment options indicated for every cancer stage. Beyond clinical practice, TNMhas been a fundamental taxonomy and used for research purposes. However, during the previous two decades, oncology knowledge has increased exponentially, while, in our opinion, the TNM system update has evolved at a more conservative rate.