CAR T cells and the future of HIV therapy

CAR T cells and the future of HIV therapy

Chimeric antigen receptor (CAR) T cells have been studied for over 25 years and are very successful in some types of cancer. With more than 30 million people living with HIV infection there were great hopes that CAR T cells method can help achieve “cure” but unfortunately after 15 years of clinical trials they have not shown to be effective.

What are CAR T cells?

Chimeric antigen receptor (CAR) T cells are obtained from donor lymphocytes, and then they are genetically modified and transfused back to the donor. They are designed to redirect T cells that express specific cell-surface epitopes which induce Major Histocompatibility Complex (MHC) – independent cytotoxic T lymphocytes response.

When this method was used in relapsed/refractory leukaemia they have achieved 67% 6-month survival rate in comparison to less than 25% with best available chemotherapy. These results raised high hopes for the potential effect of CAR T cells in HIV treatment.

What are the potential advantages of CAR T cells to target HIV-infected cells?

  • CAR T cells are independent of MCH and can target HIV-infected cells that are not targeted by host cytotoxic T lymphocytes (CTLs). HIV nef downregulates MHC-I expression; immune exhaustion or immune tolerance;
  • CAR T cells can keep their cytotoxic activity for at least 6 months and CAR DNA has been detected in peripheral blood for up to 10 years, which could potentially provide protection of HIV-expressing cells and cells that reactivate in the future;
  • CAR T cells have been found to penetrate blood-brain barrier, where is an important HIV reservoir.

Clinical trials with first generation CAR T cells

First generation CAR T cells use CD4 cells to target HIV Env-expressing cells. There were 4 clinical trials using this approach and while the CAR T cells were detected at least 10 years and there were no adverse events, the treatment did not achieve statistically significant effect on viral load. This led to discontinuation of further research.

First generation CAR T cells were relatively ineffective in cancer too.

Clinical trials with second generation CAR T cells

Second generation CAR T cells use CD28 or 4-1BB which are important for lymphocytes activation and persistence. They have proved to be significantly more effective than first generation. This second generation is used in cell cultures and has shown promising results in reducing HIV-infected cells. However there are no in vivo results yet.

There are some positive signs in second generation CAR T cells testing and this is still exciting field to keep up to date with.


Quarter Century of Anti-HIV CAR T Cells

Published on 1 Nov 2018

Author: Olga Peycheva, Director at Solutions OP Ltd. 
Olga has been working in clinical research since 2005 and has extensive experience in Eastern and Western Europe

Clinical trial design and patients with brain metastases

Clinical trial design and patients with brain metastases

The most common spread of metastatic solid tumours in central nerve system (CNS) is as parenchymal brain metastases or as leptomeningeal disease (metastases in brain membrane or spinal cord). Because the brain is protected by blood-brain barrier many drugs in standard dose will not achieve the required concentrations to be effective in CNS. Some anti-cancer drugs, however, do not cross blood-brain barrier at all but activate lymphocytes that can penetrate to CNS; while other drugs do not have effect on CNS.

For many experimental anti-cancer therapeutics there may be not sufficient information regarding their activity on CNS. As a result if the studied drugs do not have effect on CNS patients with brain metastases will progress quickly and this may affect the overall outcome of the clinical trials. On the other hand if the anti-cancer drugs have CNS activity and patients with brain metastases are excluded from the clinical trials there will be no information on drug activity on CNS and patients will miss new treatment option.

What types of clinical trial designs are possible for patients with CNS disease?

Design 1 – if the drug is considered unlikely to have CNS activity or efficacy

There are 2 possible designs to overcome the challenges above:

  • Exclude patients with CNS disease
  • Exclude patients with untreated or unstable CNS disease – CNS disease has to be either asymptomatic on stable dose of corticosteroids or off corticosteroids.

Design 2 – if the drug is considered likely to have CNS activity or efficacy

  • Permit untreated CNS metastases
  • If untreated CNS disease is measurable, mandate that these lesions be captured as target lesions
  • Define whether a growing CNS lesion previously treated with radiotherapy is permissible as a target lesion
  • Standardise CNS imaging frequency
  • Define if symptomatic, or if steroids or anticonvulsants permitted initially, or later
  • Specify bicompartmental endpoints and action if progression is observed in one but not both compartments
  • For randomised studies, stratify according to:
  • Whether CNS disease is present or absent
  • Whether CNS disease is treated or untreated
  • If treated, whether CNS progression has occurred

Design 3 – if there is minimum information on drug activity on CNS

Appropriate for phase 1 studies

This model includes dose escalation until the optimum dose is achieved. Then it is followed by molecularly or histologically defined efficacy expansion cohorts; food effect and drug-drug  interaction sub-studies and CNS metastases sub-study.

Appropriate for phase 2 and 3 studies

  • Initially permit only absent or treated and non-progressing CNS metastases in general trial population
  • Permit separate single-arm early CNS cohort with defined number of patients with measurable untreated or progressing CNS disease with separate early efficacy analysis such as CNS objective response
  • Minimise risk in this early CNS cohort by only allowing in asymptomatic cases
  • Modify protocol (as either amendments or following pre-written decision pathways) as data emerge to be like either scenario A or scenario B

CNS progression is a big challenge in treating patients with metastatic solid tumours. New approaches are required to assess when patients with CNS disease could be appropriately included or excluded from clinical trials.


Clinical trial design for systemic agents in patients with brain metastases from solid tumours: a guideline by the Response Assessment in Neuro-Oncology Brain Metastases working group

Published on 1 Oct 2018

Author: Olga Peycheva, Director at Solutions OP Ltd. 
Olga has been working in clinical research since 2005 and has extensive experience in Eastern and Western Europe

B cell receptor targeting and cancer therapy

B cell receptor targeting and cancer therapy

B cell receptor is involved in the normal B cell development and immunity but also in supporting the growth and survival of malignant B cells in patients with B cell leukaemias or lymphomas. The expression of this receptor on the surface of the B cells is important for the immune response. It triggers antigen-antibody responses and B cells differentiation into plasma sells and membrane B cells.

B cells activation is mediated by activation of membrane-proximal kinases like spleen tyrosine kinase (STK), Bruton tyrosine kinase (BTK) and PI3K. In the recent years there are inhibitors which are developed to target these kinases as part of the treatment of leukaemias and lymphomas. For example, some of the approved inhibitors are: Ibrutinib (BTK inhibitor) and Idelalisib (PI3K inhibitor). However, these inhibitors are not specific to tumour cells only and they can influence other processes in the healthy cells. Currently there are in development more specific inhibitors.

The treatment responses to these inhibitors can vary depending on the B cell receptor signalling and its interaction with the microenvironment. Also the genetic background and the degree of genetic instability could activate mechanisms which could lead to resistance to these drugs.

The role of B cells in solid tumours is not established yet but B cells are discovered in solid cancers like breast, cervical, ovarian, non-small-cell lung cancer and pancreatic ductal adenocarcinoma. Tumour-infiltrated B cells and macrophages both express BTK and are targeted by BTK inhibitors.

While the kinases involved in B cell receptor activation are promising target more research is needed to develop specific inhibitors that will target cancer cells.


Targeting B cell receptor signalling in cancer: preclinical and clinical advances

Published on 3 Sep 2018

Author: Olga Peycheva, Director at Solutions OP Ltd. 
Olga has been working in clinical research since 2005 and has extensive experience in Eastern and Western Europe

DNA nanorobots and cancer treatment

DNA nanorobots and cancer treatment

A research team from National Center for Nanoscience and Technology, Beijing, China has reported an interesting and novel approach in targeting tumours. They have constructed autonomous DNA robots which were programmed to transport and deliver therapeutics directly to the tumours.

According to the research paper such DNA robots have already been studied in cell cultures and insects but not in animals.

One of the potential new methods to target solid tumours is vascular occlusion, which is a process of blocking the blood vessels (in this case the once that support tumour growth and spreading). The research team has decided to use this method and to target tumour cells with thrombin. Thrombin cannot exist for a long time on its own in the blood circulation and it is not specific when triggering coagulation processes.

The experiments were done with mouse models and Bama miniature pigs. They have picked Bama miniature pigs because their physiology is closer to humans. Also they have run experiments with different types of tumours with different level of vascularization. The final results have shown that the DNA nanorobots have successfully delivered thrombin to the tumours and have blocked the blood supplies to them without affecting surrounding cells.

According to the authors this is an important step forward in developing method which will allow targeting tumours and blocking formation of metastasis.

It is definitely a very promising field with great potential.


A DNA nanorobot functions as a cancer therapeutic in response to a molecular trigger in vivo

Published on 1 August 2018

Author: Olga Peycheva, Director at Solutions OP Ltd. 
Olga has been working in clinical research since 2005 and has extensive experience in Eastern and Western Europe

FDA legislation changes and clinical trials: July 2018

FDA legislation changes and clinical trials: July 2018

FDA extends access to experimental drugs

FDA extended access program started back in 2009 and it allowed patients with life-threatening diseases who have exhausted all other options to try experimental drugs, which are not on the market yet. After the implementation the program for the period between 2009 and 2014 FDA has approved almost 6000 requests for experimental treatment, however some view the current process as ineffective.

The new legislation ‘Federal Right to Try Act’ will further increase the access to experimental drugs and change the pathway to obtain approvals. However, the agency remains committed to protect patients’ safety and provide more treatment options to patients with life-threatening diseases.


FDA prepares guidance on including adolescent in adult oncology clinical trials

It is known that cancer in young paediatric patients may differ from adults and therefor needs new approaches and treatments; there is an acute demand for treatment options for paediatric cancer patients. It was established that in some type of cancers there is similarity in paediatric and adult cancer histology and biological behaviour – for example, some soft tissue and bone sarcomas, central nervous system tumours, leukaemia, lymphomas and melanomas.

Often paediatric clinical trials are conducted long after adult trials and this could lead to delay in access to potentially effective therapies.

In June 2018 FDA released guidance on inclusion of adolescents (age between 12 and 17 years) in clinical trials. The guideline outlines appropriate criteria for inclusion of adults and adolescents at different stages of drug development; recommendations regarding dosing, pharmacokinetics, safety, monitoring and ethical considerations.

According to the guide doses have to be selected based on whether the adult dose is fixed or based on body size; dosing should be supported by pharmacokinetic characteristics of the drug, the therapeutic index of the drug and dose- and exposure-response relationships. Pharmacokinetic samples for adolescents should be collected according to the drug development programme to verify exposure in adolescents and adults. In case of body size-adjusted dosing adolescents should receive the same body size-adjusted dose as adults; however if it is fixed dose then a minimum body weight threshold should be defined to prevent adolescents with a lower than average body weight from exceeding adult exposure. While in early drug development long term safety follow up may not be possible the guide recommends sponsors to develop plan for long term safety evaluation where feasible. Under the federal regulations, IRBs reviewing adult oncology clinical trials that allow for the enrolment of adolescents must ensure that the provisions of 21 CFR Part 50, Subpart D (‘Additional Safeguards for Children in Clinical Investigations’) and 21 CFR 50.52 (‘Clinical Investigations involving Greater than Minimal Risk but Presenting the Prospect of Direct Benefit to Individual Subjects’) are satisfied before approving the trials.


Circulating tumor cells and their future in oncology diagnostic

Circulating tumor cells and their future in oncology diagnostic

Circulating tumour cells (CTCs) are rare tumor cells that have been investigated for diagnostic, prognosis and predictive biomarkers for different types of cancer. CTCs have been described back in 1869. They are not used in clinical practice at the moment, however CTCs were explored in breast, lung, prostate and colorectal cancers.

How rare are CTCs?

There is approximately 1 circulating tumor cell per ml of blood released by primary tumors or metastases that can be detected in peripheral blood.

What types of circulating tumor cells exist in clinical practice?

  1. Treatment based on CTCs used as liquid biopsy: Biopsies are invasive, expensive, time-consuming and potential harmful so using CTCs is one way of avoiding this procedure.
  2. Treatment based on CTC count or CTC variations: This depends on technique used and volume of blood screened.
  3. Treatment based on CTC biomarker expression: Isolating single cell of CTCs could be challenging.

What are the challenges of using circulating tumor cells in cancer screening?

Usage of Cellsearch technique in early non-metastatic cancer have shown low CTC detection rates (5-30% depending on the cancer type). This method is limited to some circulating epithelial cells so it cannot be used wildly. Unfortunately other techniques have not shown better detection rates.

How could CTCs be used as prognostic value?

Analysis of 1944 patients with breast cancer using CellSearch has shown that patients with increased CTCs have poor prognosis and decreased progression-free survival. Also evaluating CTCs count at baseline allows better prognosis of survival. Similar results are observed in patients with metastatic colon cancer, castration-resistant prostate cancer and small cell and non-small cell lung cancer.

CTCs value as prognostic factor was also observed in non-metastatic cancers with similar correlation – the higher amount of CTCs means poor prognosis.

How could CTCs be used in monitoring treatment response?

Studies with patients with metastatic breast cancer have shown that women with high baseline CTC counts, which is reduced after one cycle of chemotherapy have better prognosis than patients where their CTC count is elevated.

While CTCs have great potential as prognostic factor and in monitoring therapy, there are still lots of challenges before their implementation in clinical practise with biggest among them – discovering new methods and techniques for detection of CTCs.


Circulating tumor cells: clinical validity and utility

Published on 2 July 2018

Author: Olga Peycheva, Director at Solutions OP Ltd. 
Olga has been working in clinical research since 2005 and has extensive experience in Eastern and Western Europe