Aparna Kalyan

Repurposing metformin for cancer treatment: current clinical studies

In recent years, several studies have presented evidence suggesting a potential role for metformin in anti-cancer therapy. Preclinical studies have demonstrated several anticancer molecular mechanisms of metformin including mTOR inhibition, cytotoxic effects, and immunomodulation. Epidemiologic data have demonstrated decreased cancer incidence and mortality in patients taking metformin. Several clinical trials, focused on evaluation of metformin as an anti-cancer agent are presently underway. Data published from a small number of completed trials has put forth intriguing results. Clinical trials in pre-surgical endometrial cancer patients exhibited a significant decrease in Ki67 with metformin monotherapy. Another interesting observation was made in patients with breast cancer, wherein a trend towards improvement in cancer proliferation markers was noted in patients without insulin resistance. Data on survival outcomes with the use of metformin as an anti-cancer agent is awaited. This manuscript will critically review the role of metformin as a potential cancer treatment.

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.

Concordance between genomic alterations assessed by next-generation sequencing in tumor tissue or circulating cell-free DNA

Genomic analysis of tumor tissue is the standard technique for identifying DNA alterations in malignancies. Genomic analysis of circulating tumor cell-free DNA (cfDNA) represents a relatively non-invasive method of assessing genomic alterations using peripheral blood. We compared the concordance of genomic alterations between cfDNA and tissue biopsies in this retrospective study. Twenty-eight patients with advanced solid tumors with paired next-generation sequencing tissue and cfDNA biopsies were identified. Sixty-five genes were common to both assays. Concordance was defined as the presence or absence of the identical genomic alteration(s) in a single gene on both molecular platforms. Including all aberrations, the average number of alterations per patient for tissue and cfDNA analysis was 4.82 and 2.96, respectively. When eliminating alterations not detectable in the cfDNA assay, mean number of alterations for tissue and cfDNA was 3.21 and 2.96, respectively. Overall, concordance was 91.9–93.9%. However, the concordance rate decreased to 11.8–17.1% when considering only genes with reported genomic alterations in either assay. Over 50% of mutations detected in either technique were not detected using the other biopsy technique, indicating a potential complementary role of each assay. Across 5 genes (TP53, EGFR, KRAS, APC, CDKN2A), sensitivity and specificity were 59.1% and 94.8%, respectively. Potential explanations for the lack of concordance include differences in assay platform, spatial and temporal factors, tumor heterogeneity, interval treatment, subclones, and potential germline DNA contamination. These results highlight the importance of prospective studies to evaluate concordance of genomic findings between distinct platforms that ultimately may inform treatment decisions.

Immunotherapy in lung cancer

Immunotherapy has emerged in recent years as a promising therapeutic approach in lung cancer. Two approaches are of particular interest: immune checkpoint inhibition, which aims to counteract the physiologic mechanisms of immune tolerance co-opted by some tumors, and vaccine therapy, which enables enhanced exposure to tumor antigen. Immune checkpoint therapies include the monoclonal antibody blockade of the cytotoxic T-lymphocyte antigen-4 (CTLA-4) with ipilimumab, as well as antibody blockade of the programmed cell death-1 (PD-1) receptor and the PD-1 ligand. These immune checkpoint therapies have been evaluated in both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) with early evidence of activity. Vaccines include antigen specific therapies which induce specific antitumor immunity against relevant tumor-associated antigens. In lung cancer, these include the melanoma-associated antigen-A3 (MAGE-A3), membrane-associated glycoprotein (MUC-1), and the epidermal growth factor receptor (EGFR). Whole tumor vaccines have also been evaluated in lung cancer and influence the patients immune system to allow recognition of the tumor as foreign creating de novo immunity. This review summarizes the evidence to date for the efficacy and safety of immunotherapies in lung cancer.

Adenoid cystic carcinoma: current therapy and potential therapeutic advances based on genomic profiling

Adenoid cystic carcinoma (ACC) is a rare cancer with high potential for recurrence and metastasis. Efficacy of current treatment options, particularly for advanced disease, is very limited. Recent whole genome and exome sequencing has dramatically improved our understanding of ACC pathogenesis. A balanced translocation resulting in the MYB-NFIB fusion gene appears to be a fundamental signature of ACC. In addition, sequencing has identified a number of other driver genes mutated in downstream pathways common to other well-studied cancers. Overexpression of oncogenic proteins involved in cell growth, adhesion, cell cycle regulation, and angiogenesis are also present in ACC. Collectively, studies have identified genes and proteins for targeted, mechanism-based, therapies based on tumor phenotypes, as opposed to nonspecific cytotoxic agents. In addition, although few studies in ACC currently exist, immunotherapy may also hold promise. Better genetic understanding will enable treatment with novel targeted agents and initial exploration of immune-based therapies with the goal of improving outcomes for patients with ACC.

FGFR3-TACC3 fusion in solid tumors: mini review

Fibroblast growth factor receptors (FGFR) are transmembrane kinase proteins with growing importance in cancer biology given the frequency of molecular alterations and vast interface with multiple other signaling pathways. Furthermore, numerous FGFR inhibitors in clinical development demonstrate the expanding therapeutic relevance of this pathway. Indeed, results from early phase clinical trials already indicate that a subset of patients with advanced tumors derive benefit from FGFR targeted therapies. FGFR gene aberrations and FGFR gene rearrangements are relatively rare in solid malignancies. The recently described FGFR3-TACC3 fusion protein has a constitutively active tyrosine kinase domain and promotes aneuploidy. We summarize the prevalence data on FGFR3-TACC3 fusions among different histological tumor types and the preliminary evidence that this rearrangement represents a targetable molecular aberration in some patients with solid tumors.

Genomic landscape of DNA repair genes in cancer

DNA repair genes are frequently mutated in cancer, yet limited data exist regarding the overall genomic landscape and functional implications of these alterations in their entirety. We created comprehensive lists of DNA repair genes and indirect caretakers. Mutation, copy number variation (CNV), and expression frequencies of these genes were analyzed in COSMIC. Mutation co-occurrence, clinical outcomes, and mutation burden were analyzed in TCGA. We report the 20 genes most frequently with mutations (n > 19,689 tumor samples for each gene), CNVs (n > 1,556), or up- or down-regulated (n = 7,998). Mutual exclusivity was observed as no genes displayed both high CNV gain and loss or high up- and down-regulation, and CNV gain and loss positively correlated with up- and down-regulation, respectively. Co-occurrence of mutations differed between cancers, and mutations in many DNA repair genes were associated with higher total mutation burden. Mutation and CNV frequencies offer insights into which genes may play tumor suppressive or oncogenic roles, such as NEIL2 and RRM2B, respectively. Mutual exclusivities within CNV and expression frequencies, and correlations between CNV and expression, support the functionality of these genomic alterations. This study provides comprehensive lists of candidate genes as potential biomarkers for genomic instability, novel therapeutic targets, or predictors of immunotherapy efficacy.

Systemic Therapy of Hepatocellular Carcinoma: Current and Promising

Treatment of advanced hepatocellular carcinoma (HCC) remains challenging, particularly with the limited systemic therapy options. Sorafenib remains the only approved, targeted molecule for the treatment of advanced HCC. Although a survival benefit was demonstrated with sorafenib, it remains only true in the population of patients with Child-Turcotte-Pugh class A disease. Sorafenib also has distinct side effects that require close monitoring. Newer tyrosine kinase inhibitors and angiogenic inhibitors have been evaluated with disappointing results, particularly in phase III trials. Herein we review the pertinent trials for targeted therapy in HCC to date.

Gemcitabine/nab-paclitaxel as second-line therapy following FOLFIRINOX in metastatic/advanced pancreatic cancer—retrospective analysis of response

BACKGROUND Given the tolerability of nPG in first-line therapy, we desired to evaluate the response and toxicity profiles of second-line gemcitabine with nab-paclitaxel (nPG) following FOLFIRINOX. Methods: We retrospectively identified 30 patients who received first-line FOLFIRINOX for unresectable or metastatic pancreatic adenocarcinoma followed by second-line nPG. Response was evaluated by RECIST criteria and carbohydrate antigen 19-9 (CA19-9) change. RESULTS Median age was 63 years with 77% percent having metastatic disease. Nineteen patients (63%) achieved PR based on CA19-9. Median overall survival (OS) with nPG was 12.4 months (mo) and median progression-free survival (PFS) was 3.7 mo. Median PFS and OS for patients with at least stable CA19-9 were 4.7 and 13.9 mo since initiation of nPG. Patients with an increased CA19-9 level during nPG had a shorter median PFS (1.4 mo) and OS (5.3 mo). A significant PFS difference was demonstrated in patients with at least stable disease as the best RECIST response versus in those with progressive disease (5.4 vs. 1.9 mo, P<0.001). Grade 3/4 adverse events include thrombocytopenia (33%), anemia (23%), nausea (17%), lymphopenia (7%), infectious complications (6%), diarrhea (3%), and neuropathy (3%). CONCLUSIONS This study demonstrates a clinical benefit of second-line nPG. The study also suggests a possible use of CA19-9 to predict response to therapy.

Pseudoprogression in microsatellite instability-high colorectal cancer during treatment with combination T cell mediated immunotherapy: a case report and literature review

Evading tumor-mediated immunosuppression through antibodies to immune checkpoints has shown clinical benefit in patients with select solid tumors. There is a heterogeneity of responses in patients receiving immunotherapy, including pseudoprogression in which the tumor burden increases initially before decreasing to reach disease control. The characteristics and basis of pseudoprogression, however, remains poorly understood. We hereby report a case of microsatellite instability (MSI)-high metastatic colorectal cancer treated with combination of OX40 agonist and programmed death ligand-1 (PD-L1) antagonist that demonstrated pseudoprogression reaching 163% increase from baseline tumor burden. Tumor regression was subsequently observed and patient has remained in stable disease. Despite the substantial radiological progression, the symptomatic improvement reported by the patient led us to the decision of treatment continuation based on the suspicion of pseudoprogression, illustrating the importance of clinical evaluation in medical decision making while managing patients on immunotherapy. Additionally, the patients MSI-high status contributes to his good, maintained response to PD-L1 blockade. Our case provides a frame of reference for fluctuation in tumor burden associated with pseudoprogression. Here we also evaluate the incidence and scale of pseudoprogression across solid tumor types.Evading tumor-mediated immunosuppression through antibodies to immune checkpoints has shown clinical benefit in patients with select solid tumors. There is a heterogeneity of responses in patients receiving immunotherapy, including pseudoprogression in which the tumor burden increases initially before decreasing to reach disease control. The characteristics and basis of pseudoprogression, however, remains poorly understood. We hereby report a case of microsatellite instability (MSI)-high metastatic colorectal cancer treated with combination of OX40 agonist and programmed death ligand-1 (PD-L1) antagonist that demonstrated pseudoprogression reaching 163% increase from baseline tumor burden. Tumor regression was subsequently observed and patient has remained in stable disease. Despite the substantial radiological progression, the symptomatic improvement reported by the patient led us to the decision of treatment continuation based on the suspicion of pseudoprogression, illustrating the importance of clinical evaluation in medical decision making while managing patients on immunotherapy. Additionally, the patients MSI-high status contributes to his good, maintained response to PD-L1 blockade. Our case provides a frame of reference for fluctuation in tumor burden associated with pseudoprogression. Here we also evaluate the incidence and scale of pseudoprogression across solid tumor types.