Circulating tumor cells as a biomarker for monitoring: Disease progression, treatment response, and minimal residual disease

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Background: To analyze the role of Circulating tumor cells (CTC) as a confirmatory personalized biomarker for monitoring the disease progression, disease burden, and minimal residual disease in epithelial origin cancers. Methods: In this retrospective study, 127 patients with colorectal, breast, and ovarian cancer at stage III and IV were analyzed. The patients were at various stages of intensive chemo and radiotherapy while the CTCs were isolated and enumerated from 1.5 ml of blood. The decision to continue chemotherapy or change to oral metronomic therapy was based on the presence of circulating tumor cells in Stage III. While in stage IV, serial measurement of CTC guided therapy. CTCs were isolated using OncoDiscover platform possessing EpCAM antibody based immunomagnetic targeting of magnetic nanoparticles after RBC lysis. CTCs were imaged and identified as CK18+ and CD45- cells showing a well-defined nucleus using a motorized fluorescence microscope operational with a monochrome camera. CTCs were enumerated using automated image analysis software and counts were expressed as number per 1.5 ml of blood. Results: In this retrospective study we analyzed blood sample from 127 patients with the advanced stage epithelial cancers (breast- 50 %, ovarian -27 %, colorectal- 23 %) for the presence of CTCs. Amongst those, 52 % showed the presence of CTCs (breast- 52 %, ovarian -46 %, colorectal- 58 %). The CTC count ranged between 1-5 / 1.5 ml of blood with mean and median value of 2 and 1. Among the CTC positive population, majority had CTC count of 1 (44.4 %), while more than 2 CTCs were observed in 11 % of population. CTC clusters were detected in 13 % of population which predominantly were stage IV patients. 67 % among the follow up patients showed decrease in CTC count from the baseline due to the prescribed treatment, while 22 % patients showed increase in CTC count from the baseline. 11 % patients did not show change in CTC count from the baseline. When CTCs count was investigated as an independent variable to monitor the therapeutic response, it correlated well with the positive or negative outcome. In few representative cases, the reduction of CTC number from the basal value was indicative of an effective treatment. Exceptionally, in a representative colorectal cancer case, PET showed no primary as well secondary tumor burden, but the presence of CTCs in blood led further investigating an abdominal MRI that indicated multiple liver lesions suggesting micro-metastasis. Subsequent to SIRT treatment, the patient showed complete tumor regression and absence of CTCs in peripheral blood. Conclusions: Our data suggest that CTC can serve as a dynamic intermittent biomarker for monitoring the disease progression in advanced stages and assess the therapeutic response, thus emphasizing the role of CTCs in personalized cancer management.

A feasibility study of EMF(erlotinib+methotrexate+5-fluorouracil) regimen in recurrent head and neck squamous cell carcinoma (HNSCC) and role of circulating tumour cells(CTCs) in assessment of outcomes

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Background: Head and neck cancer is a huge burden in South East Asia with frequent relapse after curative therapy while the rest presenting in advanced unresectable stages. Financial constraints for targeted and immunotherapy make it inaccessible for the bulk of population. Thus, low-cost but efficacious regimen is highly implicated. We assessed if readily available triplet therapy of EMF, is superior in terms of extending life and maintaining quality of life along with evaluation of CTCs as a predictive biomarker in such patients. Methods: This was a single arm, phase II, investigator initiated interventional study, wherein 35 patients were enrolled. Platinum resistant/refractory patients of HNSCC were treated with combination of erlotinib 150mg daily, methotrexate 40 mg/m2 and 5-fluourouracil 500 mg/m2 (d1, d8) q28 days till progression or unacceptable toxicities. The primary endpoint was overall response rate(ORR) at 3 months; additional endpoints were disease control rate(DCR) at 3 months, overall survival (OS), progression free survival (PFS) safety and patient reported quality of life(QOL). The role of CTCs in gauging the responders and non-responders was monitored using anti Epithelial Cell Adhesion Molecule antibody based enrichment - OncoDiscover Drug Controller General of India (DCGI) approved platform. Results: The ORR and DCR at 3 months was 45.7% and 68.5%, respectively. The median PFS was 5 months (95%CI: 3.9-6 months) and median OS was 9 months (95%CI:7.4 -10.5 months). The 3 and 6 months PFS rates was 86 + 6% and 45 + 9%, respectively, while OS rates at 3 and 6 months were 91+ 5% and 68+ 8%, respectively. Rash, mucositis and fatigue were common adverse events occurring in 23 (65%), 14 (40%) and 9 (25.7%) respectively. The grade 3 events seen were rash in 5 (14.2%) and diarrhea in 2 (5.7%). Clinically significant improvement was seen in domains of role functioning, social functioning, fatigue, pain and global health status, swallowing, dryness of mouth and feeling ill. The mean CTC count at baseline was 0.90 + 1.1 /1.5ml of blood. Responders showed decline in levels from 1.19 + 0.25 to 0.33 + 0.48, while non-responders had increasing trend: 0.29 + 0.48 to 1+ 0.10 at 3 months (p = 0.010); with concordance rates with response being 52.9%. Additionally, CTC clearance at 3 months had numerically better PFS ̃ 6 months (95% CI: 4.72-7.72) and OS of 10 months (95% CI: 2.3-5.65) vs 4 months (95% CI: 2.3-5.65), p = 0.258 and 8 months (95% CI: 4.3-11.6), p = 0.203 in those with persistence of CTCs. Conclusions: The triplet regimen of EMF is a feasible, safe therapeutic option with favourable response rates and improved QOL in patients with platinum resistant/refractory HNSCC. CTCs have a promising futuristic role as a predictive biomarker and can be extrapolated in clinical upfront setting too. Clinical trial information: CTRI/2020/02/023378.

Circulating tumor cells demonstrate a positive biomarker in head and neck squamous cell carcinoma (HNSCC) in tobacco consuming population of Bangladesh

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Background: Tobacco consumption accounts for 1.6 million deaths annually in the South East Asia Region (SEAR). Notably, amongst 10-20% of the global population consuming the betel quid and tobacco, about 81% concentration is in SEAR regions, including India and Bangladesh. The prevalence of HNSCC in these regions is rising alarmingly. For example, HNCs account for 23% of total 156775 cancer incidences in Bangladesh. Liquid biopsy tools are unavailable and expensive for most patients in this region. However, early cancer detection using tumor biomarkers, for example, Circulating Tumor Cells (CTCs) is highly implicated. Furthermore, such biomarkers are being validated and have potential for screening of high-risk patients, such as genetic predisposition, tobacco consumption, etc. We report the first observational study in HNSCC patients in Bangladesh correlating the presence of CTCs to chronic tobacco consumption. Methods: The study involved 70 cancer patients and 10 healthy volunteers (no prior cancer history). 87% of the patients had a specified history of chronic tobacco consumption. CTCs were isolated in 1.5 ml of blood using OncoDiscover Liquid Biopsy Test, which is clinically approved by the Drug Controller General of India, that contains an enriching anti-EPCAM antibody immunomagnetic kit. CTCs are qualified as CK18+, DAPI+and CD45-. Subsequently, CTCs were imaged using Zeiss Axio Observer 7 and quantified for Mean Fluorescence Intensity (MFI) for clinicopathological parameters; age/gender, HNSCC sub-population, and CTC distribution. Results: This is the 1st study on Bangladesh phenotype accounting for the presence of CTCs in HNSCC patients. In this population, 34 males (66%) and 10 females (52%) accounted for 91 CTCs. CTC distribution was 0 to 6 with mean and median ̃ 2.02 and 2, respectively. 25 patients (17 males, 8 females) were negative for any CTCs. Interestingly, 02 patients exhibited CTC clusters indicative of aggressive metastasis in which 01 patient had no prior tobacco usage or family cancer history. There was no correlation between CTC presence in males (66 %) and females (52 %). Healthy volunteer samples exhibited no false positives. The MFI values ranged between 23 and 766, with mean and median MFI values were 157 and 96, respectively, indicative of CK overexpression on CTCs of HNSCC patients. Conclusions: HNSCC patients with a history of chronic tobacco consumption in Bangladesh correlated the presence of CTCs in 64 % of the cases. Prospectively, CTCs may be validated as a biomarker for screening chronic tobacco users in Bangladesh to detect early cancers and HNSCC. Clinical trial information: BMRC/Grants/2018/99 (1-100).

A highly efficient, low-cost, novel multicomponent nanosystem for rapid enumeration of circulating tumor cells

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Background: ‘Liquid biopsy’ technologies are unaffordable and unavailable in developing countries despite having highest cancer burden and mortality rates. Current Circulating Tumor Cell (CTCs) technologies sustain clinical concerns of a) non-specificity b) low efficiency c) high blood volume requirement d) long turn-around time, and d) exorbitant cost (~$900-1400). We report, an extremely low cost, innovative nanosystem for rapid enumeration of CTS with higher specificity and efficiency. Methods: We designed a nanosystem mediated by conjugation of anti-EpCAM through multi-reactive glutathione spacer, carbon allotrope and amine terminated dendrimer. The platform was evaluated for enhanced aqueous dispersibility and increased interaction with CTCs for rapid isolation and enumeration in 100 Head and Neck Cancer (HNC) patients having primary tumor sub-sites-oral cavity, larynx, hypopharynx, oropharynx, nasopharynx, salivary gland, and thyroid. The captured cells were immuno-stained and the optimal fluorescence acquisition intensity was validated in accounting CTCs with CK18 protein expression. There was complete elimination of the false positive normal cells (NC) count to CTCs by our method. The analysis was performed with only 1.5 ml of collected blood samples. Results: The CTC distribution in cohort study ranged from 1 - 85 cells per 1.5 mL of blood. In more than 80% of patient’s CTCs, the quantitative estimation of anti-CK18 protein over-expression indicated ~10-fold higher intensity over to NCs. As compared to treatment naive, recurrent, and disease-free patients, the spread of CTC number across the clinical range appeared to be tight (close to mean value). The CTC enumeration sensitivity linearity was ~99.2%, and the complete enumeration process time was under 03 hours/1.5 ml of blood. Consequently, efficient, rapid and yet affordable CTC platform was designed and clinically validated. Conclusions: ‘OncoDiscover’ liquid biopsy technology for CTC enumeration is poised to revolutionize the liquid biopsy due to its high sensitivity and affordability (~ $120) and shall resolve a major unmet medical need in impoverished world.

(α,α-dimethyl)glycyl (dmg) PNAs: achiral PNA analogs that form stronger hybrids with cDNA relative to isosequential RNA

The design and facile synthesis of sterically constrained new analogs of PNA having gem-dimethyl substitutions on glycine (dmg-PNA-T) is presented. The PNA oligomers [aminoethyl dimethylglycyl (aedmg) and aminopropyl dimethylglycyl (apdmg)] synthesized from the monomers 6 and 12) effected remarkable stabilization of homothyminePNA₂:homoadenine DNA/RNA triplexes and mixed base sequence duplexes with target cDNA or RNA. They show a higher binding to DNA relative to that with isosequential RNA. This may be a structural consequence of the sterically rigid gem-dimethyl group, imposing a pre-organized conformation favorable for complex formation with cDNA. The results complement our previous work that had demonstrated that cyclohexanyl-PNAs favor binding with cRNA compared with cDNA and imply that the biophysical and structural properties of PNAs can be directed by introduction of the right rigidity in PNA backbone devoid of chirality. This approach of tweaking selectivity in binding of PNA constructs by installing gem-dimethyl substitution in PNA backbone can be extended to further fine-tuning by similar substitution in the aminoethyl segment as well either individually or in conjunction with present substitution.

Property editing of peptide nucleic acids (PNA): gem-dimethyl, cyanuryl and 8-aminoadenine PNAs

We herein describe the introduction of gem-dimethyl substitution into the aminoethylglycyl backbone of PNA to impart steric constraint and pre-organise PNA for selective recognition of nucleic acids. Introduction of cyanuric acid and 8-aminoadenine as pyrimidine and purine analogs that can form base pairing from either face is also described to overcome the rotameric problems in PNA sidechain orientations and thereby enhance the statistical probability for base pairing. The UV-thermal melting studies of the derived triplexes with complementary DNA provide support for this rationale.

Isothermal titration calorimetry studies on the binding of DNA bases and PNA base monomers to gold nanoparticles

An isothermal titration calorimetric (ITC) investigation of the interaction of DNA bases and PNA base monomers with gold nanoparticles is described revealing a binding sequence in the order C > G > A > T. Direct measurement of the strength of interaction of ligands with nanogold by ITC has important implications in surface modification strategies for biomedical, catalysis, and nanoarchitecture applications.