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Refers to: http://www.popsci.com/why-are-scientists-shocked-by-results-this-cancer-treatment-trial

Yes, impressive results but no more impressive than the original CAR-T (Chimeric antigen receptor) results that Carl June got back in 2013 (1). Early days yet, too far-fetched to call it cure, it’s more accurate to say cancer immunotherapy has curative potential. Need longer-term follow-up of patients treated with immunotherapy. Do they stay cancer-free or does it recur? Also important to note that so far, most of the favorable data are for blood, specifically B cell, tumors.

Can immunotherapy be made effective against solid tumors? Most anti-solid tumor immunotherapy approaches tried thus far only prolonged life for a few months at disproportionately high cost (see figure below from 2).

Other important unanswered questions

  • How to minimize collateral damage to healthy, non-cancerous tissues? This is even more of a pressing problem with a lot of solid tumors where tumor-specific antigens haven’t been clearly identified yet. Tumor-specific antigens are key to ensure cancer immunotherapies maximize on-target (cancer) effect while minimizing off-target (healthy cell/tissue) toxicities.
  • In addition, if immunotherapy consists of T cells,
    • How to make them persist in the body?
    • How to make them home to tumors?

At present, too many biotech companies are each working separately on their chosen magic bullets, a classic silo situation when for many tumors, especially solid tumors with poor prognosis with standard Rx, a collaborative approach combining a variety of immuotherapies offers better hope for effective treatment. To make these different approaches work synergistically requires collaboration between experts on immune checkpoint inhibitors be they mAbs (monoclonal antibodies) or bi-specific antibodies, CAR-Ts or TILs (tumor infiltrating leukocytes) to mention a few. Currently the biotech landscape simply isn’t geared for collaborative work on such combination therapies. Things will change in this direction if and when specific government incentives such as Joe Biden’s ‘moon shot to cure cancer‘ are fully funded to support an integrated, multi-disciplinary approach to cancer research. This would incentivize a shift at least in the government-funded research landscape away from silos. Meantime, some of the many approaches being funded by private investment likely won’t pan out as solo remedies but that’s not a total loss since it would improve the chances of their being used in combination therapies instead.

Note of caution is thus necessary. Yes, there are early promising CAR-T data on a handful of patients but they are largely for blood or immune cell cancers. Sustained data by many groups on remission in more number of patients, on patients with solid tumors, not just blood or immune cell cancers, longer-term (several years) remission-free survival, these are the kinds of results that would indicate that immunotherapy has become a reliable arm of cancer Rx.

Foot-notes

1. Has Carl June Found a Key to Fighting Cancer? Jason Fagone, PhillyMag, July 25, 2013. Has Carl June Found a Key to Fighting Cancer? | Philadelphia magazine

2.  Dai, Hanren, et al. “Chimeric Antigen Receptors Modified T-Cells for Cancer Therapy.” Journal of the National Cancer Institute 108.7 (2016): djv439. Chimeric Antigen Receptors Modified T-Cells for Cancer Therapy

https://www.quora.com/Is-immunotherapy-the-closest-thing-we-have-to-a-cure-for-cancer/answer/Tirumalai-Kamala

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