One more thing I have been yelling about for years!!! Medicine now has the technology to determine all sorts of things via a simple blood draw. Circulating tiny bits of tumor DNA floating through our blood can tell docs what type of tumor we have, predict response to a given treatment and let us know how the treatment is working. Here is a link to years of posts: Circulating DNA in melanoma treatment from 2014 til now!!
Now there's this:
Programmed death 1 (PD1) inhibitors are now a foundation of medical management of metastatic melanoma. This study sought to determine whether circulating tumour DNA (ctDNA) provides useful early response and prognostic information.
We evaluated the relationship between pre-treatment and early on treatment ctDNA and outcome in melanoma patients treated with PD1 inhibitors alone or in combination with ipilimumab.
ctDNA was detected in 40/76 patients (53%) at baseline, and correlated with stage, LDH levels, disease volume and ECOG performance. RECIST response was 72% (26/36) in Group A (undetectable ctDNA at baseline), 77% (17/22) in Group B (elevated ctDNA at baseline but undetectable within 12 weeks of therapy) and 6% (1/18) in Group C (elevated ctDNA at baseline and remained elevated during treatment). The median PFS was not reached in groups A and B and was 2.7 months for Group C. The median OS was not reached for Groups A and B and was 9.2 months for Group C . The poor outcome measures associated with Group C remained significant in multivariate analysis adjusted for LDH, performance status, tumour stage and disease volume. The predictive value for ctDNA for response was confirmed in a separate validation cohort.
Longitudinal assessment of ctDNA in metastatic melanoma patients receiving treatment with PD1 inhibitors is an accurate predictor of tumour response, PFS and OS. Patients who had a persistently elevated ctDNA on therapy had a poor prognosis, and this may guide combination and sequencing of subsequent therapies.