A Prospective Observational Study of Clinico-Pathological Features, Prognostic Factors and Treatment Response to Primary Therapy in Multiple Myeloma at a Tertiary Care Centre

Title: "A prospective observational study of clinico-pathological features, prognostic factors and treatment response to primary therapy in Multiple Myeloma at a tertiary care centre"

Background: Multiple myeloma (MM) is characterised by the neoplastic proliferation of plasma cells leading to excess monoclonal immunoglobulins. The incidence of multiple myeloma in India ranges from 1.2 to 1.8 per 100,000. There is paucity of cytogenetic data from this part of subcontinent. The aim of our study is to report various clinicopathological features, evaluate biological markers of prognostication including cytogenetic variables and assess treatment response after standard primary therapy.

Methods and Materials: The study was carried out at a tertiary care center in Northern India. After final diagnosis of multiple myeloma was established, each patient was risk stratified via FISH cytogenetic analysis as per the revised ISS. Definitive management plan was individualised, including assessment for high dose therapy with peripheral blood stem cell support. Treatment response were recorded as per standard IMWG response criteria. Significant toxicities associated with treatment were also recorded.

Results: Eighty consecutive patients with newly diagnosed multiple myeloma were enrolled prospectively from April 2017 to November 2018. The median age at diagnosis was 63 years, and number of males & females were equal. The most common presenting symptom was back pain (67.8 % patients) and most frequent clinical sign was pallor (86.4 %). All four CRAB features were documented only in 16.9% patients. M-Band was present in 96.6% patients and on SFLC assay 59.3% and 40.7% were kappa and lambda light chain restricted respectively. Most common heavy chain abnormality detected was IgG. Seventy percent patients had lytic lesions on imaging while only 3% suffered skeletal related events.

Cytogenetic evaluation by interphase FISH was carried out in all patients upfront. No chromosomal abnormality was documented in 61.25 % while among those with chromosomal abnormalities, most commonly detected was del13q14.3 (23.75 %). Overall, 66.6% patients were stratified as standard risk, 28.1% as intermediate risk and only 3 (5.3%) patients were categorised as high risk.

Most common induction regimen was VRD. Overall response rate was 94.9 % and VGPR or better responses were observed in 77.9% patients. Most common adverse effect of therapy was peripheral neuropathy of all grades. Of the 77 patients who completed primary therapy, 21.4% patients underwent high dose therapy with peripheral blood stem cell support while 67.7% patients were started on maintenance therapy. Four (5.1 %) non-responder was started on 2nd line treatment. On univariate analysis, higher deeper responses (VGPR or better) were observed in patients with IgA & IgG related myeloma and better overall response rates were seen in IgG related myeloma. Those with kappa light chain myeloma had 5.67 times higher likelihood of achieving response as compared to lambda light chain myeloma. Also, patients with kappa light chain myeloma achieved higher VGPRs as compared to lambda light chain myeloma. There was 17 times high risk of non-response in the presence of local bony tenderness. None of the findings were found to be significant on multivariate analysis.

Conclusions:

Use of interphase FISH to identify various cytogenetic markers help in stratification & staging of the disease which in turn act as a marker for prognostication. They should be a part of standard care in multiple myeloma. In majority we could administer treatment in accordance to standard practice guidelines and response rates were similar to those reported my seminal studies. Our study in a longer follow up will yield some useful information which will help in the better care of the patients.