News in Brief: High TMB fails to predicts immunotherapy response for all cancers; Cryoablation funding for RCC; Physician chronic care model on RACP Budget wish list


22 Mar 2021

High TMB fails to predicts immunotherapy response for all cancers

A large analysis of patient tumour data has failed to support the use of high tumour mutational burden (TMB)  as a universal biomarker for immunotherapy response.

In the most comprehensive analysis of TMB status to date researchers from the MD Anderson Cancer Center in the US analysed over 10,000 tumours across 31 cancer types from The Cancer Genome Atlas (TCGA) to study the relationship between TMB status and tumour immunogenicity.

They identified two classes of tumours – those with a strong correlation between TMB status and T cell infiltration and those without.

For cancers in the first category, such as melanoma, lung, and bladder cancers, patients with a high TMB had improved clinical outcomes. Across all cancer types in this category, patients with a high TMB had a 39.8% overall response rate to checkpoint inhibitors, which was significantly higher than those with a low TMB.

However, TMB status was not predictive of outcome in the second class of tumours, such as breast cancer, prostate cancer, and glioma. Within this category, patients with a high TMB had a 15.3% overall response rate, which was lower than the response rate for patients with low TMB, they noted.

According to investigators classification of high TMB varies by cancer type across different DNA sequencing assays.

They say the finding is particularly important in light of the recent FDA approval of pembrolizumab for the treatment of patients with any unresectable or metastatic tumour. The indication is for patients with no mismatch repair deficiency or microsatellite instability (MSI) that is TMB high and has progressed on prior therapy with no alternative treatment options. In the approval, TMB-H was defined as ≥10 mut/Mb.

Writing in Annals of Oncology investigators caution that the FDA threshold is suboptimal for predicting ORR and OS following ICI treatment across the multiple cancer types where there is no or low correlation between TMB status and T cell infiltration.

“For those cancer types where a high TMB does not appear to increase immunogenicity, additional prospective studies are needed to determine if TMB status can be an effective clinical biomarker and at what threshold,” they said.

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Cryoabalation reimbursement recommended for small renal masses

The Medicare Services Advisory Committee (MSAC) has backed an application for MBS funding of cryoablation for biopsy-confirmed renal cell carcinoma (RCC) ≤4 cm in patients not suitable for partial nephrectomy (PN).

MSAC accepted that cryoablation in the proposed population was safe, effective and cost-effective compared with active surveillance/delayed therapy

The committee said it was advised that currently there is no evidence that one form of ablative therapy (CA, radiofrequency ablation [RFA] or microwave ablation [MWA]) is clinically or ontologically superior to the other forms of energy ablation.

 It noted that small renal masses (SRMs) are increasingly detected at early asymptomatic stage due to the increasing use of diagnostic imaging (ultrasound and CT) to investigate abdominal symptoms.

Physician chronic care model on RACP Budget wish list

The RACP is calling on government to provide more funding for telehealth, digital health record uptake incentives and a physician chronic disease care model in its Pre-Budget Submission for 2021-2022.

In its submission entitled: Reimagining Health Post COVID-19: Reform for preventive, sustainable and equitable health, the RACP makes 48 recommendations that include:

  • Funding a model of care for the management of patients with comorbid chronic health conditions that formalises and supports the integration of consultant physician care (the RACP Model of Chronic Care Management or a variation).
  • Additional funding for videoconferencing technology packages for priority populations to promote equitable access to telehealth.
  • Maintain funding for Specialist Training Program (STP) positions while allowing for some flexibility for medical specialty variations to the recently introduced rural training requirements.
  • Provide a Practice Incentive Payment for consultant physicians to support better digital infrastructure to promote access to telehealth and the delivery of integrated multidisciplinary care.
  • Introduce specialist health items to the MBS to facilitate secondary consultations with GPs and other types of specialists, and allied health providers, with or without the patient present.


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