The results were not surprising for me — because the focus was on a single drug.
Overall response rates were 35.1% in the placebo group and 26.0% in the rituximab group (difference, 9.2 percentage points [95% CI, -5.5 to 23.3 percentage points]; P = 0.22). The treatment groups did not differ in fatigue score over 24 months (difference in average score, 0.02 [CI, -0.27 to 0.31]; P = 0.80) or any of the secondary end points. Twenty patients (26.0%) in the rituximab group and 14 (18.9%) in the placebo group had serious adverse events.B-Lymphocyte Depletion in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial [April 2019]
The Rituximab saga began in 2004 when two oncologists noticed that Rituximab – a B-cell depleting drug often used in cancer – not only cured one of their patient’s cancer but eliminated their chronic fatigue syndrome (ME/CFS) as well. After two more ME/CFS patients responded similarly, they began their work on ME/CFS in earnest.Norwegian Rituximab Chronic Fatigue Syndrome (ME/CFS) Trial Fails 
I have personally met two people with CFS that had cancer — and the CFS disappeared with the cancer treatment (usually included chemotherapy).
Cancer+CFS is not a CFS microbiome
A search on pub med for cancer and microbiome returns over 4400 studies. Cancer causes a change of the microbiome — yes, it may still be dysfunctional but it is dysfunctional in another way. The full cancer treatment protocol appears to reset the microbiome (likey by devastating it).
- Regulatory T Cells and Plasmacytoid Dendritic Cells Within the Tumor Microenvironment in Gastric Cancer Are Correlated With Gastric Microbiota Dysbiosis: A Preliminary Study .
- [Carcinogenesis and Gut Microbiota]. 2019
- Gut microbiota, chemotherapy and the host: the influence of the gut microbiota on cancertreatment. 
Chemotherapy and radiotherapy treatment regimens for gastrointestinal, peritoneal and pelvic tumours can disrupt the intestinal microbiomeand intestinal epithelia. Such disturbances can provoke symptoms such as diarrhoea, nausea and vomiting. Chemotherapy and radiotherapy induced gastrointestinal toxicity aggravating intestinal microbiome dysbiosis is postulated to adversely alter the intestinal microbiome, with a consequent induced pro-inflammatory effect that disrupts the intestinal microbiome-epithelia-mucosal immunity axis.The role of adjuvant probiotics to attenuate intestinal inflammatory responses due to cancer treatments.